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[Git][ghc/ghc][wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL] 3 commits: ci: Javascript don't set CROSS_EMULATOR
by Sven Tennie (＠supersven) 31 Dec '25

31 Dec '25

Sven Tennie pushed to branch wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL at Glasgow Haskell Compiler / GHC Commits: 264060a2 by Matthew Pickering at 2025-12-31T17:10:07+01:00 ci: Javascript don't set CROSS_EMULATOR There is no CROSS_EMULATOR needed to run javascript binaries, so we don't set the CROSS_EMULATOR to some dummy value. - - - - - 3433717e by Sven Tennie at 2025-12-31T17:10:07+01:00 Javascript skip T23697 See #22355 about how HSC2HS and the Javascript target don't play well together. - - - - - 2fd4bf52 by Sven Tennie at 2025-12-31T17:10:07+01:00 testsuite: Stabilize T24602 I don't get *why*, however the final js file seems to be written asynchronuously. So, we wait until it's around. - - - - - 4 changed files: - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - libraries/base/tests/all.T - testsuite/tests/javascript/closure/Makefile Changes: ===================================== .gitlab/generate-ci/gen_ci.hs ===================================== @@ -139,9 +139,11 @@ bignumString :: BignumBackend -> String bignumString Gmp = "gmp" bignumString Native = "native" +data TimeoutIncrease = TimeoutIncrease | NoTimeoutIncrease + data CrossEmulator = NoEmulator - | NoEmulatorNeeded + | NoEmulatorNeeded TimeoutIncrease | Emulator String -- | A BuildConfig records all the options which can be modified to affect the @@ -889,16 +891,20 @@ job arch opsys buildConfig = NamedJob { name = jobName, jobInfo = Job {..} } NoEmulator -- we need an emulator but it isn't set. Won't run the testsuite | Just _ <- crossTarget buildConfig - -> "CROSS_EMULATOR" =: "NOT_SET" - | otherwise -> mempty - Emulator s -> "CROSS_EMULATOR" =: s - NoEmulatorNeeded -> mempty + -> "CROSS_EMULATOR" =: "NOT_SET" + | otherwise -> mempty + Emulator s -> "CROSS_EMULATOR" =: s + NoEmulatorNeeded _ -> mempty , if withNuma buildConfig then "ENABLE_NUMA" =: "1" else mempty - , let testTimeoutArg = + , let + -- Emulators are naturally slower than native machines. + -- Triple the default of 300. + timeoutConf = "-e config.timeout=900" + testTimeoutArg = case crossEmulator buildConfig of - -- Emulators are naturally slower than native machines. - -- Triple the default of 300. - Emulator _ -> "-e config.timeout=900" :: String + Emulator _ -> timeoutConf + -- NodeJS (Javascript) is slower than native code + NoEmulatorNeeded TimeoutIncrease -> timeoutConf _ -> mempty runtestArgs = testTimeoutArg : @@ -1309,7 +1315,7 @@ cross_jobs = [ (validateBuilds AArch64 (Linux Debian12Wine) (winAarch64Config {llvmBootstrap = True})) ] where - javascriptConfig = (crossConfig "javascript-unknown-ghcjs" (Emulator "js-emulator") (Just "emconfigure")) + javascriptConfig = (crossConfig "javascript-unknown-ghcjs" (NoEmulatorNeeded TimeoutIncrease) (Just "emconfigure")) { bignumBackend = Native } makeWinArmJobs = modifyJobs @@ -1354,7 +1360,7 @@ cross_jobs = [ $ addValidateRule WasmBackend $ validateBuilds Amd64 (Linux AlpineWasm) cfg wasm_build_config = - (crossConfig "wasm32-wasi" NoEmulatorNeeded Nothing) + (crossConfig "wasm32-wasi" (NoEmulatorNeeded NoTimeoutIncrease) Nothing) { hostFullyStatic = True , buildFlavour = Release -- TODO: This needs to be validate but wasm backend doesn't pass yet , textWithSIMDUTF = True ===================================== .gitlab/jobs.yaml ===================================== @@ -2118,7 +2118,6 @@ "BUILD_FLAVOUR": "validate", "CONFIGURE_ARGS": "--with-intree-gmp --enable-strict-ghc-toolchain-check", "CONFIGURE_WRAPPER": "emconfigure", - "CROSS_EMULATOR": "js-emulator", "CROSS_STAGE": "2", "CROSS_TARGET": "javascript-unknown-ghcjs", "INSTALL_CONFIGURE_ARGS": "--enable-strict-ghc-toolchain-check", @@ -6292,7 +6291,6 @@ "BUILD_FLAVOUR": "validate", "CONFIGURE_ARGS": "--with-intree-gmp --enable-strict-ghc-toolchain-check", "CONFIGURE_WRAPPER": "emconfigure", - "CROSS_EMULATOR": "js-emulator", "CROSS_STAGE": "2", "CROSS_TARGET": "javascript-unknown-ghcjs", "INSTALL_CONFIGURE_ARGS": "--enable-strict-ghc-toolchain-check", ===================================== libraries/base/tests/all.T ===================================== @@ -318,6 +318,7 @@ test('T23687', normal, compile_and_run, ['']) test('T23697', [ when(opsys('mingw32'), skip) # header not found , when(opsys('darwin'), skip) # permission denied + , js_broken(22355) ], makefile_test, ['T23697']) test('stimesEndo', normal, compile_and_run, ['']) test('T24807', exit_code(1), compile_and_run, ['']) ===================================== testsuite/tests/javascript/closure/Makefile ===================================== @@ -13,4 +13,10 @@ T24602: --emit_use_strict \ --js_output_file ./T24602.jsexe/all.min.js \ ./T24602.jsexe/all.js ./T24602.jsexe/all.externs.js + # For odd reasons, the final js file might not be finally written at this + # line. This happens when tests run concurrently (e.g. on CI). + while [ ! -f "./T24602.jsexe/all.min.js" ]; do \ + sync \ + sleep 1; \ + done node ./T24602.jsexe/all.min.js View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/2b84ec2875431f7fc4b7ac4a8ef8c5… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/2b84ec2875431f7fc4b7ac4a8ef8c5… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL] 10 commits: hadrian: Build stage 2 cross compilers
by Sven Tennie (＠supersven) 31 Dec '25

31 Dec '25

Sven Tennie pushed to branch wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL at Glasgow Haskell Compiler / GHC Commits: 77d28819 by Matthew Pickering at 2025-12-31T17:05:55+01:00 hadrian: Build stage 2 cross compilers * Most of hadrian is abstracted over the stage in order to remove the assumption that the target of all stages is the same platform. This allows the RTS to be built for two different targets for example. * Abstracts the bindist creation logic to allow building either normal or cross bindists. Normal bindists use stage 1 libraries and a stage 2 compiler. Cross bindists use stage 2 libararies and a stage 2 compiler. * hadrian: Make binary-dist-dir the default build target. This allows us to have the logic in one place about which libraries/stages to build with cross compilers. Fixes #24192 New hadrian target: * `binary-dist-dir-cross`: Build a cross compiler bindist (compiler = stage 1, libraries = stage 2) This commit also contains various changes to make stage2 compilers feasible. ------------------------- Metric Decrease: ManyAlternatives MultiComponentModulesRecomp MultiLayerModulesRecomp T10421 T12425 T12707 T13035 T13379 T15703 T16577 T18698a T18698b T18923 T1969 T21839c T3294 T4801 T5030 T5321Fun T5642 T783 T9198 T9872d T9961 parsing001 T5321FD T6048 ------------------------- Co-authored-by: Sven Tennie <sven.tennie(a)gmail.com> - - - - - e17cd567 by Sven Tennie at 2025-12-31T17:05:55+01:00 Align CI scripts with master Fixup - - - - - 805240dd by Matthew Pickering at 2025-12-31T17:05:55+01:00 ci: Test cross bindists We remove the special logic for testing in-tree cross compilers and instead test cross compiler bindists, like we do for all other platforms. - - - - - 4ac3b608 by Matthew Pickering at 2025-12-31T17:05:55+01:00 ci: Introduce CROSS_STAGE variable In preparation for building and testing stage3 bindists we introduce the CROSS_STAGE variable which is used by a CI job to determine what kind of bindist the CI job should produce. At the moment we are only using CROSS_STAGE=2 but in the future we will have some jobs which set CROSS_STAGE=3 to produce native bindists for a target, but produced by a cross compiler, which can be tested on by another CI job on the native platform. CROSS_STAGE=2: Build a normal cross compiler bindist CROSS_STAGE=3: Build a stage 3 bindist, one which is a native compiler and library for the target - - - - - 4a00a543 by Matthew Pickering at 2025-12-31T17:05:55+01:00 hadrian: Refactor system-cxx-std-lib rules0 I noticed a few things wrong with the hadrian rules for `system-cxx-std-lib` rules. * For `text` there is an ad-hoc check to depend on `system-cxx-std-lib` outside of `configurePackage`. * The `system-cxx-std-lib` dependency is not read from cabal files. * Recache is not called on the packge database after the `.conf` file is generated, a more natural place for this rule is `registerRules`. Treating this uniformly like other packages is complicated by it not having any source code or a cabal file. However we can do a bit better by reporting the dependency firstly in `PackageData` and then needing the `.conf` file in the same place as every other package in `configurePackage`. Fixes #25303 - - - - - 28249a93 by Sven Tennie at 2025-12-31T17:05:55+01:00 ci: Increase timeout for emulators Test runs with emulators naturally take longer than on native machines. Generate jobs.yml - - - - - 66606edb by Sven Tennie at 2025-12-31T17:05:55+01:00 ghc: Distinguish between having an interpreter and having an internal one Otherwise, we fail with warnings when compiling tools. Actually, these are related but different things: - ghc can run an interpreter (either internal or external) - ghc is compiled with an internal interpreter - - - - - e8fe46a6 by Matthew Pickering at 2025-12-31T17:05:55+01:00 ci: Javascript don't set CROSS_EMULATOR There is no CROSS_EMULATOR needed to run javascript binaries, so we don't set the CROSS_EMULATOR to some dummy value. - - - - - 03f2eedd by Sven Tennie at 2025-12-31T17:05:55+01:00 Javascript skip T23697 See #22355 about how HSC2HS and the Javascript target don't play well together. - - - - - 2b84ec28 by Matthew Pickering at 2025-12-31T17:05:55+01:00 ci: Javascript don't set CROSS_EMULATOR There is no CROSS_EMULATOR needed to run javascript binaries, so we don't set the CROSS_EMULATOR to some dummy value. We want to keep the increased timeout settings, though. Co-authored-by: Sven Tennie <sven.tennie(a)gmail.com> - - - - - 68 changed files: - .gitlab/ci.sh - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - configure.ac - distrib/configure.ac.in - ghc/GHC/Driver/Session/Mode.hs - ghc/GHCi/UI.hs - ghc/Main.hs - ghc/ghc-bin.cabal.in - hadrian/README.md - hadrian/bindist/config.mk.in - + hadrian/cfg/system.config.host.in - hadrian/cfg/system.config.in - + hadrian/cfg/system.config.target.in - hadrian/hadrian.cabal - hadrian/src/Base.hs - + hadrian/src/BindistConfig.hs - hadrian/src/Builder.hs - hadrian/src/Context.hs - hadrian/src/Expression.hs - hadrian/src/Flavour.hs - hadrian/src/Flavour/Type.hs - hadrian/src/Hadrian/Builder.hs - hadrian/src/Hadrian/Haskell/Cabal/Parse.hs - hadrian/src/Hadrian/Haskell/Cabal/Type.hs - hadrian/src/Hadrian/Haskell/Hash.hs - hadrian/src/Hadrian/Oracles/TextFile.hs - hadrian/src/Oracles/Flag.hs - hadrian/src/Oracles/Flavour.hs - hadrian/src/Oracles/Setting.hs - hadrian/src/Oracles/TestSettings.hs - hadrian/src/Packages.hs - hadrian/src/Rules.hs - hadrian/src/Rules/BinaryDist.hs - hadrian/src/Rules/CabalReinstall.hs - hadrian/src/Rules/Compile.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Rules/Generate.hs - hadrian/src/Rules/Gmp.hs - hadrian/src/Rules/Libffi.hs - hadrian/src/Rules/Library.hs - hadrian/src/Rules/Program.hs - hadrian/src/Rules/Register.hs - hadrian/src/Rules/Rts.hs - hadrian/src/Rules/Test.hs - hadrian/src/Settings.hs - hadrian/src/Settings/Builders/Cabal.hs - hadrian/src/Settings/Builders/Common.hs - hadrian/src/Settings/Builders/Configure.hs - hadrian/src/Settings/Builders/DeriveConstants.hs - hadrian/src/Settings/Builders/Ghc.hs - hadrian/src/Settings/Builders/Hsc2Hs.hs - hadrian/src/Settings/Builders/RunTest.hs - hadrian/src/Settings/Builders/SplitSections.hs - hadrian/src/Settings/Default.hs - hadrian/src/Settings/Flavours/Benchmark.hs - hadrian/src/Settings/Flavours/Development.hs - hadrian/src/Settings/Flavours/GhcInGhci.hs - hadrian/src/Settings/Flavours/Performance.hs - hadrian/src/Settings/Flavours/Quick.hs - hadrian/src/Settings/Flavours/QuickCross.hs - hadrian/src/Settings/Flavours/Quickest.hs - hadrian/src/Settings/Flavours/Validate.hs - hadrian/src/Settings/Packages.hs - hadrian/src/Settings/Program.hs - hadrian/src/Settings/Warnings.hs - libraries/base/tests/all.T - testsuite/ghc-config/ghc-config.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/dfe9142cfbd96e7a8b4da730cfa5c3… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/dfe9142cfbd96e7a8b4da730cfa5c3… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL] testsuite: Stabilize T24602
by Sven Tennie (＠supersven) 31 Dec '25

31 Dec '25

Sven Tennie pushed to branch wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL at Glasgow Haskell Compiler / GHC Commits: dfe9142c by Sven Tennie at 2025-12-31T13:51:19+01:00 testsuite: Stabilize T24602 I don't get *why*, however the final js file seems to be written asynchronuously. So, we wait until it's around. - - - - - 1 changed file: - testsuite/tests/javascript/closure/Makefile Changes: ===================================== testsuite/tests/javascript/closure/Makefile ===================================== @@ -13,4 +13,10 @@ T24602: --emit_use_strict \ --js_output_file ./T24602.jsexe/all.min.js \ ./T24602.jsexe/all.js ./T24602.jsexe/all.externs.js + # For odd reasons, the final js file might not be finally written at this + # line. This happens when tests run concurrently (e.g. on CI). + while [ ! -f "./T24602.jsexe/all.min.js" ]; do \ + sync \ + sleep 1; \ + done node ./T24602.jsexe/all.min.js View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/dfe9142cfbd96e7a8b4da730cfa5c36… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/dfe9142cfbd96e7a8b4da730cfa5c36… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/T26615] 103 commits: Add a fast-path for args=[] to occAnalApp
by Simon Peyton Jones (＠simonpj) 31 Dec '25

31 Dec '25

Simon Peyton Jones pushed to branch wip/T26615 at Glasgow Haskell Compiler / GHC Commits: 48a3ed57 by Simon Peyton Jones at 2025-11-25T15:33:54+00:00 Add a fast-path for args=[] to occAnalApp In the common case of having not arguments, occAnalApp was doing redundant work. - - - - - 951e5ed9 by Simon Peyton Jones at 2025-11-25T15:33:54+00:00 Fix a performance hole in the occurrence analyser As #26425 showed, the clever stuff in Note [Occurrence analysis for join points] does a lot of duplication of usage details. This patch improved matters with a little fancy footwork. It is described in the new (W4) of the same Note. Compile-time allocations go down slightly. Here are the changes of +/- 0.5% or more: T13253(normal) 329,369,244 326,395,544 -0.9% T13253-spj(normal) 66,410,496 66,095,864 -0.5% T15630(normal) 129,797,200 128,663,136 -0.9% T15630a(normal) 129,212,408 128,027,560 -0.9% T16577(normal) 6,756,706,896 6,723,028,512 -0.5% T18282(normal) 128,462,070 125,808,584 -2.1% GOOD T18698a(normal) 208,418,305 202,037,336 -3.1% GOOD T18730(optasm) 136,981,756 136,208,136 -0.6% T18923(normal) 58,103,088 57,745,840 -0.6% T19695(normal) 1,386,306,272 1,365,609,416 -1.5% T26425(normal) 3,344,402,957 2,457,811,664 -26.5% GOOD T6048(optasm) 79,763,816 79,212,760 -0.7% T9020(optasm) 225,278,408 223,682,440 -0.7% T9961(normal) 303,810,717 300,729,168 -1.0% GOOD geo. mean -0.5% minimum -26.5% maximum +0.4% Metric Decrease: T18282 T18698a T26425 T9961 - - - - - f1959dfc by Simon Peyton Jones at 2025-11-26T11:58:07+00:00 Remove a quadratic-cost assertion check in mkCoreApp See the new Note [Assertion checking in mkCoreApp] - - - - - 98fa0d36 by Simon Hengel at 2025-11-27T17:54:57-05:00 Fix typo in docs/users_guide/exts/type_families.rst - - - - - 5b97e5ce by Simon Hengel at 2025-11-27T17:55:37-05:00 Fix broken RankNTypes example in user's guide - - - - - fa2aaa00 by Simon Peyton Jones at 2025-11-27T17:56:18-05:00 Switch off specialisation in ExactPrint In !15057 (where we re-introduced -fpolymoprhic-specialisation) we found that ExactPrint's compile time blew up by a factor of 5. It turned out to be caused by bazillions of specialisations of `markAnnotated`. Since ExactPrint isn't perf-critical, it does not seem worth taking the performance hit, so this patch switches off specialisation in this one module. - - - - - 1fd25987 by Simon Peyton Jones at 2025-11-27T17:56:18-05:00 Switch -fpolymorphic-specialisation on by default This patch addresses #23559. Now that !10479 has landed and #26329 is fixed, we can switch on polymorphic specialisation by default, addressing a bunch of other tickets listed in #23559. Metric changes: * CoOpt_Singleton: +4% compiler allocations: we just get more specialisations * info_table_map_perf: -20% decrease in compiler allocations. This is caused by using -fno-specialise in ExactPrint.hs Without that change we get a 4x blow-up in compile time; see !15058 for details Metric Decrease: info_table_map_perf Metric Increase: CoOpt_Singletons - - - - - b7fe7445 by Matthew Pickering at 2025-11-27T17:56:59-05:00 rts: Fix a deadlock with eventlog flush interval and RTS shutdown The ghc_ticker thread attempts to flush at the eventlog tick interval, this requires waiting to take all capabilities. At the same time, the main thread is shutting down, the schedule is stopped and then we wait for the ticker thread to finish. Therefore we are deadlocked. The solution is to use `newBoundTask/exitMyTask`, so that flushing can cooperate with the scheduler shutdown. Fixes #26573 - - - - - 1d4a1229 by sheaf at 2025-11-27T17:58:02-05:00 SimpleOpt: don't subst in pushCoercionIntoLambda It was noticed in #26589 that the change in 15b311be was incorrect: the simple optimiser carries two different substitution-like pieces of information: 'soe_subst' (from InVar to OutExpr) and 'soe_inl' (from InId to InExpr). It is thus incorrect to have 'pushCoercionIntoLambda' apply the substitution from 'soe_subst' while discarding 'soe_inl' entirely, which is what was done in 15b311be. Instead, we change back pushCoercionIntoLambda to take an InScopeSet, and optimise the lambda before calling 'pushCoercionIntoLambda' to avoid mixing InExpr with OutExpr, or mixing two InExpr with different environments. We can then call 'soeZapSubst' without problems. Fixes #26588 #26589 - - - - - 84a087d5 by Sylvain Henry at 2025-11-28T17:35:28-05:00 Fix PIC jump tables on Windows (#24016) Avoid overflows in jump tables by using a base label closer to the jump targets. See added Note [Jump tables] - - - - - 82db7042 by Zubin Duggal at 2025-11-28T17:36:10-05:00 rts/linker/PEi386: Copy strings before they are inserted into LoadedDllCache. The original strings are temporary and might be freed at an arbitrary point. Fixes #26613 - - - - - ff3f0d09 by Ben Gamari at 2025-11-29T18:34:28-05:00 gitlab-ci: Run ghcup-metadata jobs on OpenCape runners This significantly reduces our egress traffic and makes the jobs significantly faster. - - - - - ef0dc33b by Matthew Pickering at 2025-11-29T18:35:10-05:00 Use 'OsPath' in getModificationTimeIfExists This part of the compiler is quite hot during recompilation checking in particular since the filepaths will be translated to a string. It is better to use the 'OsPath' native function, which turns out to be easy to do. - - - - - fa3bd0a6 by Georgios Karachalias at 2025-11-29T18:36:05-05:00 Use OsPath in PkgDbRef and UnitDatabase, not FilePath - - - - - 0d7c05ec by Ben Gamari at 2025-12-01T03:13:46-05:00 hadrian: Place user options after package arguments This makes it easier for the user to override the default package arguments with `UserSettings.hs`. Fixes #25821. ------------------------- Metric Decrease: T14697 ------------------------- - - - - - 3b2c4598 by Vladislav Zavialov at 2025-12-01T03:14:29-05:00 Namespace-specified wildcards in import/export lists (#25901) This change adds support for top-level namespace-specified wildcards `type ..` and `data ..` to import and export lists. Examples: import M (type ..) -- imports all type and class constructors from M import M (data ..) -- imports all data constructors and terms from M module M (type .., f) where -- exports all type and class constructors defined in M, -- plus the function 'f' The primary intended usage of this feature is in combination with module aliases, allowing namespace disambiguation: import Data.Proxy as T (type ..) -- T.Proxy is unambiguously the type constructor import Data.Proxy as D (data ..) -- D.Proxy is unambiguously the data constructor The patch accounts for the interactions of wildcards with: * Imports with `hiding` clauses * Import warnings -Wunused-imports, -Wdodgy-imports * Export warnings -Wduplicate-exports, -Wdodgy-exports Summary of the changes: 1. Move the NamespaceSpecifier type from GHC.Hs.Binds to GHC.Hs.Basic, making it possible to use it in more places in the AST. 2. Extend the AST (type: IE) with a representation of `..`, `type ..`, and `data ..` (constructor: IEWholeNamespace). Per the proposal, the plain `..` is always rejected with a dedicated error message. 3. Extend the grammar in Parser.y with productions for `..`, `type ..`, and `data ..` in both import and export lists. 4. Implement wildcard imports by updating the `filterImports` function in GHC.Rename.Names; the logic for IEWholeNamespace is roughly modeled after the Nothing (no explicit import list) case. 5. Implement wildcard exports by updating the `exports_from_avail` function in GHC.Tc.Gen.Export; the logic for IEWholeNamespace is closely modeled after the IEModuleContents case. 6. Refactor and extend diagnostics to report the new warnings and errors. See PsErrPlainWildcardImport, DodgyImportsWildcard, PsErrPlainWildcardExport, DodgyExportsWildcard, TcRnDupeWildcardExport. Note that this patch is specifically about top-level import/export items. Subordinate import/export items are left unchanged. - - - - - c71faa76 by Luite Stegeman at 2025-12-01T03:16:05-05:00 rts: Handle overflow of ELF section header string table If the section header string table is stored in a section greater than or equal to SHN_LORESERVE (0xff00), the 16-bit field e_shstrndx in the ELF header does not contain the section number, but rather an overflow value SHN_XINDEX (0xffff) indicating that we need to look elsewhere. This fixes the linker by not using e_shstrndx directly but calling elf_shstrndx, which correctly handles the SHN_XINDEX value. Fixes #26603 - - - - - ab20eb54 by Mike Pilgrem at 2025-12-01T22:46:55+00:00 Re CLC issue 292 Warn GHC.Internal.List.{init,last} are partial Also corrects the warning for `tail` to refer to `Data.List.uncons` (like the existing warning for `head`). In module `Settings.Warnings`, applies `-Wno-x-partial` to the `filepath`, and `parsec` packages (outside GHC's repository). Also bumps submodules. - - - - - fc1d7f79 by Jade Lovelace at 2025-12-02T11:04:09-05:00 docs: fix StandaloneKindSignatures in DataKinds docs These should be `type` as otherwise GHC reports a duplicate definition error. - - - - - beae879b by Rodrigo Mesquita at 2025-12-03T15:42:37+01:00 task: Substitute some datatypes for newtypes * Substitutes some data type declarations for newtype declarations * Adds comment to `LlvmConfigCache`, which must decidedly not be a newtype. Fixes #23555 - - - - - 3bd7dd44 by mangoiv at 2025-12-04T04:36:45-05:00 Renamer: reinstate the template haskell level check in notFound Out-of-scope names might be caused by a staging error, as is explained by Note [Out of scope might be a staging error] in GHC.Tc.Utils.Env.hs. This logic was assumed to be dead code after 217caad1 and has thus been removed. This commit reintroduces it and thus fixes issue #26099. - - - - - 0318010b by Zubin Duggal at 2025-12-04T04:37:27-05:00 testlib: Optionally include the way name in the expected output file This allows us to have different outputs for different ways. - - - - - 6d945fdd by Zubin Duggal at 2025-12-04T04:37:27-05:00 testsuite: Accept output of tests failing in ext-interp way due to differing compilation requirements Fixes #26552 - - - - - 0ffc5243 by Cheng Shao at 2025-12-04T04:38:09-05:00 devx: minor fixes for compile_flags.txt This patch includes minor fixes for compile_flags.txt to improve developer experience when using clangd as language server to hack on RTS C sources: - Ensure `-fPIC` is passed and `__PIC__` is defined, to be coherent with `-DDYNAMIC` and ensure the `__PIC__` guarded code paths are indexed - Add the missing `-DRtsWay` definition, otherwise a few source files like `RtsUtils.c` and `Trace.c` would produce clangd errors - - - - - e36a5fcb by Matthew Pickering at 2025-12-05T16:25:57-05:00 Add support for building bytecode libraries A bytecode library is a collection of bytecode files (.gbc) and a library which combines together additional object files. A bytecode library is created by invoking GHC with the `-bytecodelib` flag. A library can be created from in-memory `ModuleByteCode` linkables or by passing `.gbc` files as arguments on the command line. Fixes #26298 - - - - - 8f9ae339 by Matthew Pickering at 2025-12-05T16:25:57-05:00 Load bytecode libraries to satisfy package dependencies This commit allows you to use a bytecode library to satisfy a package dependency when using the interpreter. If a user enables `-fprefer-byte-code`, then if a package provides a bytecode library, that will be loaded and used to satisfy the dependency. The main change is to separate the relevant parts of the `LoaderState` into external and home package byte code. Bytecode is loaded into either the home package or external part (similar to HPT/EPS split), HPT bytecode can be unloaded. External bytecode is never unloaded. The unload function has also only been called with an empty list of "stable linkables" for a long time. It has been modified to directly implement a complete unloading of the home package bytecode linkables. At the moment, the bytecode libraries are found in the "library-dirs" field from the package description. In the future when `Cabal` implements support for "bytecode-library-dirs" field, we can read the bytecode libraries from there. No changes to the Cabal submodule are necessary at the moment. Four new tests are added in testsuite/tests/cabal, which generate fake package descriptions and test loading the libraries into GHCi. Fixes #26298 - - - - - 54458ce4 by mangoiv at 2025-12-05T16:26:50-05:00 ExplicitLevelImports: improve documentation of the code - more explicit names for variable names like `flg` or `topLevel` - don't pass the same value twice to functions - some explanations of interesting but undocumented code paths - adjust comment to not mention non-existent error message - - - - - c7061392 by mangoiv at 2025-12-05T16:27:42-05:00 driver: don't expect nodes to exist when checking paths between them In `mgQueryZero`, previously node lookups were expected to never fail, i.e. it was expected that when calculating the path between two nodes in a zero level import graph, both nodes would always exist. This is not the case, e.g. in some situations involving exact names (see the test-case). The fix is to first check whether the node is present in the graph at all, instead of panicking, just to report that there is no path. Closes #26568 - - - - - d6cf8463 by Peng Fan at 2025-12-06T11:06:28-05:00 NCG/LA64: Simplify genCCall into two parts genCCall is too long, so it's been simplified into two parts: genPrim and genLibCCall. Suggested by Andreas Klebinger - - - - - 9d371d23 by Matthew Pickering at 2025-12-06T11:07:09-05:00 hadrian: Use a response file to invoke GHC for dep gathering. In some cases we construct an argument list too long for GHC to handle directly on windows. This happens when we generate the dependency file because the command line will contain references to a large number of .hs files. To avoid this we now invoke GHC using a response file when generating dependencies to sidestep length limitations. Note that we only pass the actual file names in the dependency file. Why? Because this side-steps #26560 - - - - - 0043bfb0 by Marc Scholten at 2025-12-06T11:08:03-05:00 update xhtml to 3000.4.0.0 haddock-api: bump xhtml bounds haddock-api: use lazy text instead of string to support xhtml 3000.4.0.0 Bumping submodule xhtml to 3000.4.0.0 add xhtml to stage0Packages remove unused import of writeUtf8File Remove redundant import Update haddock golden files for xhtml 3000.4.0.0 Metric Decrease: haddock.Cabal haddock.base - - - - - fc958fc9 by Julian Ospald at 2025-12-06T11:08:53-05:00 rts: Fix object file format detection in loadArchive Commit 76d1041dfa4b96108cfdd22b07f2b3feb424dcbe seems to have introduced this bug, ultimately leading to failure of test T11788. I can only theorize that this test isn't run in upstream's CI, because they don't build a static GHC. The culprit is that we go through the thin archive, trying to follow the members on the filesystem, but don't re-identify the new object format of the member. This pins `object_fmt` to `NotObject` from the thin archive. Thanks to @angerman for spotting this. - - - - - 0f297f6e by mangoiv at 2025-12-06T11:09:44-05:00 users' guide: don't use f strings in the python script to ensure compatibility with python 3.5 - - - - - 3bfe7aa2 by Matthew Pickering at 2025-12-07T12:18:57-05:00 ci: Try using multi repl in ghc-in-ghci test This should be quite a bit faster than the ./hadrian/ghci command as it doesn't properly build all the dependencies. - - - - - 2ef1601a by Rodrigo Mesquita at 2025-12-07T12:19:38-05:00 Stack.Decode: Don't error on bitmap size 0 A RET_BCO may have a bitmap with no payload. In that case, the bitmap = 0. One can observe this by using -ddump-bcos and interpreting ``` main = pure () ``` Observe, for instance, that the BCO for this main function has size 0: ``` ProtoBCO Main.main#0: \u [] break<main:Main,0>() GHC.Internal.Base.pure GHC.Internal.Base.$fApplicativeIO GHC.Internal.Tuple.() bitmap: 0 [] BRK_FUN <breakarray> main:Main 0 <cc> PACK () 0 PUSH_G GHC.Internal.Base.$fApplicativeIO PUSH_APPLY_PP PUSH_G GHC.Internal.Base.pure ENTER ``` Perhaps we never tried to decode a stack in which a BCO like this was present. However, for the debugger, we want to decode stacks of threads stopped at breakpoints, and these kind of BCOs do get on a stack under e.g. `stg_apply_interp_info` frames. See the accompanying test in the next commit for an example to trigger the bug this commit fixes. Fixes #26640 - - - - - 747153d2 by Rodrigo Mesquita at 2025-12-07T12:19:38-05:00 Add test for #26640 - - - - - d4b1e353 by Simon Hengel at 2025-12-10T00:00:02-05:00 Fix syntax error in gadt_syntax.rst - - - - - 91cc8be6 by Cheng Shao at 2025-12-10T00:00:43-05:00 ci: fix "ci.sh clean" to address frequent out of space error on windows runners This patch fixes the `ci.sh clean` logic to address frequent out of space error on windows runners; previously it didn't clean up the inplace mingw blobs, which is the largest source of space leak on windows runners. See added comment for detailed explanation. - - - - - fe2b79f4 by Recursion Ninja at 2025-12-10T08:34:18-05:00 Narrow before optimising MUL/DIV/REM into shifts The MUL/DIV/REM operations can be optimised into shifts when one of the operands is a constant power of 2. However, as literals in Cmm are stored as 'Integer', for this to be correct we first need to narrow the literal to the appropriate width before checking whether the literal is a power of 2. Fixes #25664 - - - - - 06c2349c by Recursion Ninja at 2025-12-10T08:34:58-05:00 Decouple 'Language.Haskell.Syntax.Type' from 'GHC.Utils.Panic' - Remove the *original* defintion of 'hsQTvExplicit' defined within 'Language.Haskell.Syntax.Type' - Redefine 'hsQTvExplicit' as 'hsq_explicit' specialized to 'GhcPass' exported by 'GHC.Utils.Panic' - Define 'hsQTvExplicitBinders' as 'hsq_explicit' specialized to 'DocNameI' exported by 'Haddock.GhcUtils'. - Replace all call sites of the original 'hsQTvExplicit' definition with either: 1. 'hsQTvExplicit' updated definition 2. 'hsQTvExplicitBinders' All call sites never entered the 'XLHsQTyVars' constructor branch, but a call to 'panic' existed on this code path because the type system was not strong enought to guarantee that the 'XLHsQTyVars' construction was impossible. These two specialized functions provide the type system with enough information to make that guarantee, and hence the dependancy on 'panic' can be removed. - - - - - ac0815d5 by sheaf at 2025-12-10T23:39:57-05:00 Quantify arg before mult in function arrows As noted in #23764, we expect quantification order to be left-to-right, so that in a type such as a %m -> b the inferred quantification order should be [a, m, b] and not [m, a, b]. This was addressed in commit d31fbf6c, but that commit failed to update some other functions such as GHC.Core.TyCo.FVs.tyCoFVsOfType. This affects Haddock, as whether we print an explicit forall or not depends on whether the inferred quantification order matches the actual quantification order. - - - - - 2caf796e by sheaf at 2025-12-10T23:39:57-05:00 Haddock: improvements to ty-var quantification This commit makes several improvements to how Haddock deals with the quantification of type variables: 1. In pattern synonyms, Haddock used to jumble up universal and existential quantification. That is now fixed, fixing #26252. Tested in the 'PatternSyns2' haddock-html test. 2. The logic for computing whether to use an explicit kind annotation for a type variable quantified in a forall was not even wrong. This commit improves the heuristic, but it will always remain an imperfect heuristic (lest we actually run kind inference again). In the future (#26271), we hope to avoid reliance on this heuristic. - - - - - b14bdd59 by Teo Camarasu at 2025-12-10T23:40:38-05:00 Add explicit export list to GHC.Num Let's make clear what this module exports to allow us to easily deprecate and remove some of these in the future. Resolves https://gitlab.haskell.org/ghc/ghc/-/issues/26625 - - - - - d99f8326 by Cheng Shao at 2025-12-11T19:14:18-05:00 compiler: remove unused CPP code in foreign stub This patch removes unused CPP code in the generated foreign stub: - `#define IN_STG_CODE 0` is not needed, since `Rts.h` already includes this definition - The `if defined(__cplusplus)` code paths are not needed in the `.c` file, since we don't generate C++ stubs and don't include C++ headers in our stubs. But it still needs to be present in the `.h` header since it might be later included into C++ source files. - - - - - 46c9746f by Cheng Shao at 2025-12-11T19:14:57-05:00 configure: bump LlvmMaxVersion to 22 This commit bumps LlvmMaxVersion to 22; 21.x releases have been available since Aug 26th, 2025 and there's no regressions with 21.x so far. This bump is also required for updating fedora image to 43. - - - - - 96fce8d0 by Cheng Shao at 2025-12-12T01:17:51+01:00 hadrian: add support for building with UndefinedBehaviorSanitizer This patch adds a +ubsan flavour transformer to hadrian to build all stage1+ C/C++ code with UndefinedBehaviorSanitizer. This is particularly useful to catch potential undefined behavior in the RTS codebase. - - - - - f7a06d8c by Cheng Shao at 2025-12-12T01:17:51+01:00 ci: update alpine/fedora & add ubsan job This patch updates alpine image to 3.23, fedora image to 43, and adds a `x86_64-linux-fedora43-validate+debug_info+ubsan` job that's run in validate/nightly pipelines to catch undefined behavior in the RTS codebase. - - - - - 2ccd11ca by Cheng Shao at 2025-12-12T01:17:51+01:00 rts: fix zero-length VLA undefined behavior in interpretBCO This commit fixes a zero-length VLA undefined behavior in interpretBCO, caught by UBSan: ``` +rts/Interpreter.c:3133:19: runtime variable length array bound evaluates to non-positive value 0 ``` - - - - - 4156ed19 by Cheng Shao at 2025-12-12T01:17:51+01:00 rts: fix unaligned ReadSpB in interpretBCO This commit fixes unaligned ReadSpB in interpretBCO, caught by UBSan: ``` +rts/Interpreter.c:2174:64: runtime load of misaligned address 0x004202059dd1 for type 'StgWord', which requires 8 byte alignment ``` To perform proper unaligned read, we define StgUnalignedWord as a type alias of StgWord with aligned(1) attribute, and load StgUnalignedWord instead of StgWord in ReadSpB, so the C compiler is aware that we're not loading with natural alignment. - - - - - fef89fb9 by Cheng Shao at 2025-12-12T01:17:51+01:00 rts: fix signed integer overflow in subword arithmetic in interpretBCO This commit fixes signed integer overflow in subword arithmetic in interpretBCO, see added note for detailed explanation. - - - - - 3c001377 by Cheng Shao at 2025-12-13T05:03:15-05:00 ci: use treeless fetch for perf notes This patch improves the ci logic for fetching perf notes by using treeless fetch (https://github.blog/open-source/git/get-up-to-speed-with-partial-clone-and-…) to avoid downloading all blobs of the perf notes repo at once, and only fetch the actually required blobs on-demand when needed. This makes the initial `test-metrics.sh pull` operation much faster, and also more robust, since we are seeing an increasing rate of 504 errors in CI when fetching all perf notes at once, which is a major source of CI flakiness at this point. Co-authored-by: Codex <codex(a)openai.com> - - - - - 123a8d77 by Peter Trommler at 2025-12-13T05:03:57-05:00 Cmm: remove restriction in MachOp folding - - - - - 0b54b5fd by Andreas Klebinger at 2025-12-13T05:04:38-05:00 Remove explicit Typeable deriviations. - - - - - 08b13f7b by Cheng Shao at 2025-12-13T05:05:18-05:00 ci: set gc.auto=0 during setup stage This patch sets `gc.auto=0` during `setup` stage of CI, see added comment for detailed explanation. - - - - - 3b5aecb5 by Ben Gamari at 2025-12-13T23:43:10+01:00 Bump exceptions submodule to 0.10.11 - - - - - c32de3b0 by Johan Förberg at 2025-12-15T02:36:03-05:00 base: Define Semigroup and Monoid instances for lazy ST CLC proposal: https://github.com/haskell/core-libraries-committee/issues/374 Fixes #26581 - - - - - 4f8b660c by mangoiv at 2025-12-15T02:37:05-05:00 ci: do not require nightly cabal-reinstall job to succeed - - - - - 2c2a3ef3 by Cheng Shao at 2025-12-15T11:51:53-05:00 docs: drop obsolete warning about -fexternal-interpreter on windows This patch drops an obsolete warning about -fexternal-interpreter not supported on windows; it is supported since a long time ago, including the profiled way. - - - - - 68573aa5 by Marc Scholten at 2025-12-15T11:53:00-05:00 haddock: Drop Haddock.Backends.HaddockDB as it's unused - - - - - b230d549 by mangoiv at 2025-12-16T15:17:45-05:00 base: generalize delete{Firsts,}By When we delete{Firsts,}By we should not require the lists to be the same type. This is an especially useful generalisation in the case of deleteFirstsBy because we can skip an invocation of the map function. This change was discussed on the core-libraries-committee's bug tracker at https://github.com/haskell/core-libraries-committee/issues/372. - - - - - 6a2b43e3 by Cheng Shao at 2025-12-16T15:18:30-05:00 compiler: clean up redundant LANGUAGE pragmas This patch bumps `default-language` of `ghc`/`ghc-bin` from `GHC2021` to `GHC2024` (which is supported in ghc 9.10, current boot ghc lower version bound), and also cleans up redundant `LANGUAGE` pragmas (as well as `default-extensions`/`other-extensions`) that are already implied by `GHC2024`. Co-authored-by: Codex <codex(a)openai.com> - - - - - fca9cd7c by sheaf at 2025-12-18T13:18:18-05:00 X86 CodeGen: fix assign_eax_sse_regs We must set %al to the number of SSE2 registers that contain arguments (in case we are dealing with a varargs function). The logic for counting how many arguments reside in SSE2 registers was incorrect, as it used 'isFloatFormat', which incorrectly ignores vector registers. We now instead do case analysis on the register class: is_sse_reg r = case targetClassOfReg platform r of RcFloatOrVector -> True RcInteger -> False This change is necessary to prevent segfaults in T20030_test1j, because subsequent commits change the format calculations, resulting in vector formats more often. - - - - - 53150617 by sheaf at 2025-12-18T13:18:19-05:00 X86 regUsageOfInstr: fix format for IMUL When used with 8-bit operands, the IMUL instruction returns the result in the lower 16 bits of %rax (also known as %ax). This is different than for the other sizes, where an input at 16, 32 or 64 bits will result in 16, 32 or 64 bits of output in both %rax and %rdx. This doesn't affect the behaviour of the compiler, because we don't allow partial writes at sub-word sizes. The rationale is explained in Wrinkle [Don't allow scalar partial writes] in Note [Register formats in liveness analysis], in GHC.CmmToAsm.Reg.Liveness. - - - - - c7a56dd1 by sheaf at 2025-12-18T13:18:19-05:00 Liveness analysis: consider register formats This commit updates the register allocator to be a bit more careful in situations in which a single register is used at multiple different formats, e.g. when xmm1 is used both to store a Double# and a DoubleX2#. This is done by introducing the 'Regs' newtype around 'UniqSet RegWithFormat', for which the combining operations take the larger of the two formats instead of overriding the format. Operations on 'Regs' are defined in 'GHC.CmmToAsm.Reg.Regs'. There is a modest compile-time cost for the additional overhead for tracking register formats, which causes the metric increases of this commit. The subtle aspects of the implementation are outlined in Note [Register formats in liveness analysis] in GHC.CmmToAsm.Reg.Liveness. Fixes #26411 #26611 ------------------------- Metric Increase: T12707 T26425 T3294 ------------------------- - - - - - c2e83339 by sheaf at 2025-12-18T13:18:19-05:00 Register allocator: reload at same format as spill This commit ensures that if we spill a register onto the stack at a given format, we then always reload the register at this same format. This ensures we don't end up in a situation where we spill F64x2 but end up only reloading the lower F64. This first reload would make us believe the whole data is in a register, thus silently losing the upper 64 bits of the spilled register's contents. Fixes #26526 - - - - - 55ab583b by sheaf at 2025-12-18T13:18:19-05:00 Register allocation: writes redefine format As explained in Note [Allocated register formats] in GHC.CmmToAsm.Reg.Linear, we consider all writes to redefine the format of the register. This ensures that in a situation such as movsd .Ln6m(%rip),%v1 shufpd $0,%v1,%v1 we properly consider the broadcast operation to change the format of %v1 from F64 to F64x2. This completes the fix to #26411 (test in T26411b). - - - - - 951402ed by Vladislav Zavialov at 2025-12-18T13:19:05-05:00 Parser: improve mkModuleImpExp, remove checkImportSpec 1. The `mkModuleImpExp` helper now knows whether it is processing an import or export list item, and uses this information to produce a more accurate error message for `import M (T(..,x))` with PatternSynonyms disabled. The old message incorrectly referred to this case as an export form. 2. The `checkImportSpec` helper is removed in favor of more comprehensive error checking in `mkModuleImpExp`. 3. Additionaly, the invariants of `ImpExpList` and `ImpExpAllWith` have been made more explicit in the comments and assertions (calls to 'panic'). Test case: import-syntax-no-ext - - - - - 47d83d96 by Vladislav Zavialov at 2025-12-18T13:19:06-05:00 Subordinate namespace-specified wildcards (#25901) Add support for subordinate namespace-specified wildcards `X(type ..)` and `X(data ..)` to import and export lists. Examples: import M (Cls(type ..)) -- imports Cls and all its associated types import M (Cls(data ..)) -- imports Cls and all its methods module M (R(data ..), C(type ..)) where -- exports R and all its data constructors and record fields; -- exports C and all its associated types, but not its methods The scope of this change is limited to the case where the wildcard is the only subordinate import/export item, whereas the more complex forms `X(type .., f)` or `X(type .., data ..)` are unsupported and raise the newly introduced PsErrUnsupportedExplicitNamespace error. This restriction may be lifted later. Summary of the changes: 1. Refactor IEThingAll to store its extension field XIEThingAll as a record IEThingAllExt instead of a tuple. 2. Extend the AST by adding a NamespaceSpecifier field to IEThingAllExt, representing an optional namespace specifier `type` or `data` in front of a subordinate wildcard `X(..)`. 3. Extend the grammar in Parser.y with productions for `type ..` and `data ..` in subordinate import/export items. 4. Introduce `filterByNamespaceGREs` to filter [GlobalRdrElt] by a NamespaceSpecifier; use it in `filterImports` and `exports_from_avail` to account for the namespace specifier in IEThingAll. 5. Improve diagnostics by storing more information in DodgyImportsEmptyParent and DodgyExportsEmptyParent. Test cases: T25901_sub_e T25901_sub_f T25901_sub_g T25901_sub_a T25901_sub_b T25901_sub_c T25901_sub_d T25901_sub_w DodgyImports02 DodgyImports03 DodgyImports04 - - - - - eac418bb by Recursion Ninja at 2025-12-18T13:19:48-05:00 Removing the 'Data' instance for 'InstEnv'. The 'Data' instance is blocking work on Trees that Grow, and the 'Data' instance seem to have been added without a clear purpose. - - - - - e920e038 by Recursion Ninja at 2025-12-18T13:19:48-05:00 'Decouple Language.Haskell.Syntax.Decls' from 'GHC.Unit.Module.Warnings' - - - - - bd38b76c by Cheng Shao at 2025-12-18T13:20:31-05:00 testsuite: improve coverage of foundation test This patch refactors the `foundation` test a bit to improve coverage: - Instead of using a hard-coded seed, a random seed is now taken from the command line, and printed upon test failure. This improves test coverage over many future CI runs, and shall a failure occur, the seed is available in the CI log for local reproduction. - The iterations count is bumped to 1000 instead of 100, similar to the bump in `test-primops`. Runtime timeout is bumped 2x just to be safe. - Improve `newLCGGen` by using non-atomic loads/stores on a `MutableByteArray#` for storing mutable `Word64`, this test doesn't use parallelism in the first place - Fixed a few compiler warnings and removed redundant pragmas and imports Co-authored-by: Codex <codex(a)openai.com> - - - - - 3995187c by Sylvain Henry at 2025-12-18T13:21:45-05:00 Doc: document -pgmi "" (#26634) - - - - - 5729418c by Cheng Shao at 2025-12-18T13:22:29-05:00 rts: use __builtin_mul_overflow for hs_mulIntMayOflo This patch uses `__builtin_mul_overflow` to implement `hs_mulIntMayOflo`. This is a GNU C checked arithmetic builtin function supported by gcc/clang, is type-generic so works for both 32-bit/64-bit, and makes the code both more efficient and easier to read/maintain than the previous hand rolled logic. - - - - - 1ca4b49a by Cheng Shao at 2025-12-18T13:23:11-05:00 compiler/rts: fix ABI mismatch in barf() invocations This patch fixes a long-standing issue of ABI mismatch in `barf()` invocations, both in compiler-emitted code and in hand written Cmm code: - In RTS, we have `barf()` which reports a fatal internal error message and exits the program. - `barf()` is a variadic C function! When used as a callee of a foreign call with `ccall` calling convention instead of `capi`, there is an ABI mismatch between the caller and the callee! - Unfortunately, both the compiler and the Cmm sources contain many places where we call `barf()` via `ccall` convention!! Like, when you write `foreign "C" barf("foo object (%p) entered!", R1)`, it totally doesn't do what you think it'll do at all!! The second argument `R1` is not properly passed in `va_list`, and the behavior is completely undefined!! - Even more unfortunately, this issue has been sitting around long enough because the ABI mismatch is subtle enough on normie platforms like x64 and arm64. - But there are platforms like wasm32 that are stricter about ABI, and the broken `barf()` invocations already causes trouble for wasm backend: we had to use ugly hacks like `barf(errmsg, NULL)` to make `wasm-ld` happy, and even with this band-aid, compiler-generated `barf()` invocations are still broken, resulting in regressions in certain debug-related functionality, e.g. `-dtag-inference-checks` is broken on wasm32 (#22882). This patch properly fixes the issue: - We add non-variadic `barf` wrappers in the RTS that can be used as `ccall` callees - Both the compiler `emitBarf` logic and the hand-written Cmm are changed to call these wrappers - `emitBarf` now also properly annotates the foreign call as `CmmNeverReturns` to indicate it's a noreturn call to enable more efficient code generation `-dtag-inference-checks` now works on wasm. Closes #22882. Co-authored-by: Codex <codex(a)openai.com> - - - - - b3dd23b9 by Vilim Lendvaj at 2025-12-18T13:23:57-05:00 Remove outdated comment The Traversable instance for ZipList is no longer in GHC.Internal.Data.Traversable. In fact, it is right below this very comment. - - - - - 9a9c2f03 by Cheng Shao at 2025-12-18T13:24:39-05:00 compiler: remove unused OtherSection logic This patch removes the OtherSection logic in Cmm, given it's never actually used by any of our backends. - - - - - 91edd292 by Wolfgang Jeltsch at 2025-12-19T03:18:19-05:00 Remove unused known-key and name variables for generics This removes the known-key and corresponding name variables for `K1`, `M1`, `R`, `D`, `C`, `S`, and `URec` from `GHC.Generics`, as they are apparently nowhere used in GHC’s source code. - - - - - 73ee7e38 by Wolfgang Jeltsch at 2025-12-19T03:19:02-05:00 Remove unused known keys and names for generics classes This removes the known-key and corresponding name variables for `Datatype`, `Constructor`, and `Selector` from `GHC.Generics`, as they are apparently nowhere used in GHC’s source code. - - - - - f69c5f14 by Cheng Shao at 2025-12-19T03:19:45-05:00 wasm: fix handling of ByteArray#/MutableByteArray# arguments in JSFFI imports This patch fixes the handling of ByteArray#/MutableByteArray# arguments in JSFFI imports, see the amended note and manual for explanation. Also adds a test to witness the fix. Co-authored-by: Codex <codex(a)openai.com> - - - - - 224446a2 by Cheng Shao at 2025-12-20T07:49:54-05:00 rts: workaround -Werror=maybe-uninitialized false positives In some cases gcc might report -Werror=maybe-uninitialized that we know are false positives, but need to workaround it to make validate builds with -Werror pass. - - - - - 251ec087 by Cheng Shao at 2025-12-20T07:49:54-05:00 hadrian: use -Og as C/C++ optimization level when debugging This commit enables -Og as optimization level when compiling the debug ways of rts. According to gcc documentation (https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-Og) -Og is a better choice than -O0 for producing debuggable code. It's also supported by clang as well, so it makes sense to use it as a default for debugging. Also add missing -g3 flag to C++ compilation flags in +debug_info flavour transformer. - - - - - fb586c67 by Cheng Shao at 2025-12-20T07:50:36-05:00 compiler: replace DList with OrdList This patch removes `DList` logic from the compiler and replaces it with `OrdList` which also supports O(1) concatenation and should be more memory efficient than the church-encoded `DList`. - - - - - 8149c987 by Cheng Shao at 2025-12-20T17:06:51-05:00 hadrian: add with_profiled_libs flavour transformer This patch adds a `with_profiled_libs` flavour transformer to hadrian which is the exact opposite of `no_profiled_libs`. It adds profiling ways to stage1+ rts/library ways, and doesn't alter other flavour settings. It is useful when needing to test profiling logic locally with a quick flavour. - - - - - 746b18cd by Cheng Shao at 2025-12-20T17:06:51-05:00 hadrian: fix missing profiled dynamic libraries in profiled_ghc This commit fixes the profiled_ghc flavour transformer to include profiled dynamic libraries as well, since they're supported by GHC since !12595. - - - - - 4dd7e3b9 by Cheng Shao at 2025-12-20T17:07:33-05:00 ci: set http.postBuffer to mitigate perf notes timeout on some runners This patch sets http.postBuffer to mitigate the timeout when fetching perf notes on some runners with slow internet connection. Fixes #26684. - - - - - bc36268a by Wolfgang Jeltsch at 2025-12-21T16:23:24-05:00 Remove unused known keys and names for type representations This removes the known-key and corresponding name variables for `TrName`, `TrNameD`, `TypeRep`, `KindRepTypeLitD`, `TypeLitSort`, and `mkTrType`, as they are apparently nowhere used in GHC’s source code. - - - - - ff5050e9 by Wolfgang Jeltsch at 2025-12-21T16:24:04-05:00 Remove unused known keys and names for natural operations This removes the known-key and corresponding name variables for `naturalAndNot`, `naturalLog2`, `naturalLogBaseWord`, `naturalLogBase`, `naturalPowMod`, `naturalSizeInBase`, `naturalToFloat`, and `naturalToDouble`, as they are apparently nowhere used in GHC’s source code. - - - - - 424388c2 by Wolfgang Jeltsch at 2025-12-21T16:24:45-05:00 Remove the unused known key and name for `Fingerprint` This removes the variables for the known key and the name of the `Fingerprint` data constructor, as they are apparently nowhere used in GHC’s source code. - - - - - a1ed86fe by Wolfgang Jeltsch at 2025-12-21T16:25:26-05:00 Remove the unused known key and name for `failIO` This removes the variables for the known key and the name of the `failIO` operation, as they are apparently nowhere used in GHC’s source code. - - - - - b8220daf by Wolfgang Jeltsch at 2025-12-21T16:26:07-05:00 Remove the unused known key and name for `liftM` This removes the variables for the known key and the name of the `liftM` operation, as they are apparently nowhere used in GHC’s source code. - - - - - eb0628b1 by Wolfgang Jeltsch at 2025-12-21T16:26:47-05:00 Fix the documentation of `hIsClosed` - - - - - db1ce858 by sheaf at 2025-12-22T17:11:17-05:00 Do deep subsumption when computing valid hole fits This commit makes a couple of improvements to the code that computes "valid hole fits": 1. It uses deep subsumption for data constructors. This matches up the multiplicities, as per Note [Typechecking data constructors]. This fixes #26338 (test: LinearHoleFits). 2. It now suggests (non-unidirectional) pattern synonyms as valid hole fits. This fixes #26339 (test: PatSynHoleFit). 3. It uses 'stableNameCmp', to make the hole fit output deterministic. ------------------------- Metric Increase: hard_hole_fits ------------------------- - - - - - 72ee9100 by sheaf at 2025-12-22T17:11:17-05:00 Speed up hole fits with a quick pre-test This speeds up the machinery for valid hole fits by doing a small check to rule out obviously wrong hole fits, such as: 1. A hole fit identifier whose type has a different TyCon at the head, after looking through foralls and (=>) arrows, e.g.: hole_ty = Int cand_ty = Maybe a or hole_ty = forall a b. a -> b cand_ty = forall x y. Either x y 2. A hole fit identifier that is not polymorphic when the hole type is polymorphic, e.g. hole_ty = forall a. a -> a cand_ty = Int -> Int ------------------------- Metric Decrease: hard_hole_fits ------------------------- - - - - - 30e513ba by Cheng Shao at 2025-12-22T17:12:00-05:00 configure: remove unused win32-tarballs.md5sum This patch removes the unused `win32-tarballs.md5sum` file from the tree. The current mingw tarball download logic in `mk/get-win32-tarballs.py` fetches and checks against `SHA256SUM` from the same location where the tarballs are fetched, and this file has been unused for a few years. - - - - - a2d52b3b by Wolfgang Jeltsch at 2025-12-23T04:47:33-05:00 Add an operation `System.IO.hGetNewlineMode` This commit also contains some small code and documentation changes for related operations, for the sake of consistency. - - - - - b26d134a by Cheng Shao at 2025-12-23T04:48:15-05:00 rts: opportunistically reclaim slop space in shrinkMutableByteArray# Previously, `shrinkMutableByteArray#` shrinks a `MutableByteArray#` in-place by assigning the new size to it, and zeroing the extra slop space. That slop space is not reclaimed and wasted. But it's often the case that we allocate a `MutableByteArray#` upfront, then shrink it shortly after, so the `MutableByteArray#` closure sits right at the end of a nursery block; this patch identifies such chances, and also shrink `bd->free` if possible, reducing heap space fragmentation. Co-authored-by: Codex <codex(a)openai.com> ------------------------- Metric Decrease: T10678 ------------------------- - - - - - c72ddabf by Cheng Shao at 2025-12-23T16:13:23-05:00 hadrian: fix bootstrapping with ghc-9.14 This patch fixes bootstrapping GHC with ghc-9.14, tested locally with ghc-9.14.1 release as bootstrapping GHC. - - - - - 0fd6d8e4 by Cheng Shao at 2025-12-23T16:14:05-05:00 hadrian: pass -keep-tmp-files to test ghc when --keep-test-files is enabled This patch makes hadrian pass `-keep-tmp-files` to test ghc when `--keep-test-files` is enabled, so you can check the ghc intermediate files when debugging certain test failures. Closes #26688. - - - - - 81d10134 by Cheng Shao at 2025-12-24T06:11:52-05:00 configure: remove dead code in configure scripts This patch removes dead code in our configure scripts, including: - Variables and auto-detected programs that are not used - autoconf functions that are not used, or export a variable that's not used - `AC_CHECK_HEADERS` invocations that don't have actual corresponding `HAVE_XXX_H` usage - Other dead code (e.g. stray `AC_DEFUN()`) Co-authored-by: Codex <codex(a)openai.com> - - - - - fb1381c3 by Wolfgang Jeltsch at 2025-12-24T06:12:34-05:00 Remove unused known keys and names for list operations This removes the known-key and corresponding name variables for `concat`, `filter`, `zip`, and `(++)`, as they are apparently nowhere used in GHC’s source code. - - - - - 7b9c20f4 by Recursion Ninja at 2025-12-24T10:35:36-05:00 Decoupling Language.Haskell.Syntax.Binds from GHC.Types.Basic by transferring InlinePragma types between the modules. * Moved InlinePragma data-types to Language.Haskell.Syntax.Binds.InlinePragma * Partitioned of Arity type synonyms to GHC.Types.Arity * InlinePragma is now extensible via Trees That Grow * Activation is now extensible via Trees That Grow * Maybe Arity change to more descriptive InlineSaturation data-type * InlineSaturation information removed from InlinePragma during GHS parsing pass * Cleaned up the exposed module interfaces of the new modules - - - - - a3afae0c by Simon Peyton Jones at 2025-12-25T15:26:36-05:00 Check for rubbish literals in Lint Addresses #26607. See new Note [Checking for rubbish literals] in GHC.Core.Lint - - - - - e552b7fc by Simon Peyton Jones at 2025-12-31T10:40:43+00:00 Make SpecContr rules fire a bit later See #26615 - - - - - 834 changed files: - .gitattributes - .gitlab-ci.yml - .gitlab/ci.sh - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - .gitlab/rel_eng/fetch-gitlab-artifacts/fetch_gitlab.py - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - .gitlab/test-metrics.sh - compile_flags.txt - compiler/GHC.hs - compiler/GHC/Builtin/Names.hs - compiler/GHC/Builtin/PrimOps.hs - compiler/GHC/Builtin/PrimOps/Ids.hs - compiler/GHC/Builtin/Types/Literals.hs - compiler/GHC/Builtin/Utils.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Breakpoints.hs - compiler/GHC/ByteCode/InfoTable.hs - compiler/GHC/ByteCode/Instr.hs - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/ByteCode/Types.hs - compiler/GHC/Cmm.hs - compiler/GHC/Cmm/BlockId.hs - compiler/GHC/Cmm/CLabel.hs - compiler/GHC/Cmm/CommonBlockElim.hs - compiler/GHC/Cmm/Config.hs - compiler/GHC/Cmm/ContFlowOpt.hs - compiler/GHC/Cmm/Dataflow.hs - compiler/GHC/Cmm/Dataflow/Block.hs - compiler/GHC/Cmm/Dataflow/Graph.hs - compiler/GHC/Cmm/Dataflow/Label.hs - compiler/GHC/Cmm/DebugBlock.hs - compiler/GHC/Cmm/Dominators.hs - compiler/GHC/Cmm/Expr.hs - compiler/GHC/Cmm/Graph.hs - compiler/GHC/Cmm/Info/Build.hs - compiler/GHC/Cmm/LRegSet.hs - compiler/GHC/Cmm/LayoutStack.hs - compiler/GHC/Cmm/Lint.hs - compiler/GHC/Cmm/Liveness.hs - compiler/GHC/Cmm/MachOp.hs - compiler/GHC/Cmm/Node.hs - compiler/GHC/Cmm/Opt.hs - compiler/GHC/Cmm/Parser.y - compiler/GHC/Cmm/ProcPoint.hs - compiler/GHC/Cmm/Reducibility.hs - compiler/GHC/Cmm/Reg.hs - compiler/GHC/Cmm/Sink.hs - compiler/GHC/Cmm/Switch.hs - compiler/GHC/Cmm/Switch/Implement.hs - compiler/GHC/Cmm/ThreadSanitizer.hs - compiler/GHC/Cmm/UniqueRenamer.hs - compiler/GHC/Cmm/Utils.hs - compiler/GHC/CmmToAsm/AArch64/Ppr.hs - compiler/GHC/CmmToAsm/AArch64/RegInfo.hs - compiler/GHC/CmmToAsm/BlockLayout.hs - compiler/GHC/CmmToAsm/CFG.hs - compiler/GHC/CmmToAsm/CPrim.hs - compiler/GHC/CmmToAsm/Dwarf/Types.hs - compiler/GHC/CmmToAsm/Format.hs - compiler/GHC/CmmToAsm/LA64/CodeGen.hs - compiler/GHC/CmmToAsm/LA64/Ppr.hs - compiler/GHC/CmmToAsm/Monad.hs - compiler/GHC/CmmToAsm/PPC/CodeGen.hs - compiler/GHC/CmmToAsm/PPC/Ppr.hs - compiler/GHC/CmmToAsm/PPC/RegInfo.hs - compiler/GHC/CmmToAsm/Ppr.hs - compiler/GHC/CmmToAsm/RV64/CodeGen.hs - compiler/GHC/CmmToAsm/RV64/Ppr.hs - compiler/GHC/CmmToAsm/Reg/Graph.hs - compiler/GHC/CmmToAsm/Reg/Graph/Coalesce.hs - compiler/GHC/CmmToAsm/Reg/Graph/Spill.hs - compiler/GHC/CmmToAsm/Reg/Graph/SpillClean.hs - compiler/GHC/CmmToAsm/Reg/Graph/SpillCost.hs - compiler/GHC/CmmToAsm/Reg/Linear.hs - compiler/GHC/CmmToAsm/Reg/Linear/Base.hs - compiler/GHC/CmmToAsm/Reg/Linear/JoinToTargets.hs - compiler/GHC/CmmToAsm/Reg/Linear/State.hs - compiler/GHC/CmmToAsm/Reg/Linear/X86.hs - compiler/GHC/CmmToAsm/Reg/Linear/X86_64.hs - compiler/GHC/CmmToAsm/Reg/Liveness.hs - + compiler/GHC/CmmToAsm/Reg/Regs.hs - compiler/GHC/CmmToAsm/Reg/Target.hs - compiler/GHC/CmmToAsm/Wasm.hs - compiler/GHC/CmmToAsm/Wasm/Asm.hs - compiler/GHC/CmmToAsm/Wasm/FromCmm.hs - compiler/GHC/CmmToAsm/Wasm/Types.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToAsm/X86/Instr.hs - compiler/GHC/CmmToAsm/X86/Ppr.hs - compiler/GHC/CmmToC.hs - compiler/GHC/CmmToLlvm/Base.hs - compiler/GHC/CmmToLlvm/CodeGen.hs - compiler/GHC/CmmToLlvm/Data.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Coercion.hs - compiler/GHC/Core/Coercion.hs-boot - compiler/GHC/Core/Coercion/Axiom.hs - compiler/GHC/Core/DataCon.hs - compiler/GHC/Core/FamInstEnv.hs - compiler/GHC/Core/InstEnv.hs - compiler/GHC/Core/LateCC/OverloadedCalls.hs - compiler/GHC/Core/LateCC/TopLevelBinds.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Lint/Interactive.hs - compiler/GHC/Core/Make.hs - compiler/GHC/Core/Map/Expr.hs - compiler/GHC/Core/Map/Type.hs - compiler/GHC/Core/Opt/Arity.hs - compiler/GHC/Core/Opt/CSE.hs - compiler/GHC/Core/Opt/CallerCC.hs - compiler/GHC/Core/Opt/ConstantFold.hs - 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− utils/haddock/haddock-api/src/Haddock/Backends/HaddockDB.hs - utils/haddock/haddock-api/src/Haddock/Backends/Hoogle.hs - utils/haddock/haddock-api/src/Haddock/Backends/Hyperlinker.hs - utils/haddock/haddock-api/src/Haddock/Backends/Hyperlinker/Renderer.hs - utils/haddock/haddock-api/src/Haddock/Backends/LaTeX.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/DocMarkup.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Layout.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Names.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Themes.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Utils.hs - utils/haddock/haddock-api/src/Haddock/Convert.hs - utils/haddock/haddock-api/src/Haddock/Doc.hs - utils/haddock/haddock-api/src/Haddock/GhcUtils.hs - utils/haddock/haddock-api/src/Haddock/Interface/Create.hs - utils/haddock/haddock-api/src/Haddock/Utils.hs - utils/haddock/haddock-library/src/Documentation/Haddock/Parser.hs - utils/haddock/html-test/ref/Bug1050.html - utils/haddock/html-test/ref/Bug26.html - utils/haddock/html-test/ref/Bug298.html - utils/haddock/html-test/ref/Bug458.html - utils/haddock/html-test/ref/LinearTypes.html - utils/haddock/html-test/ref/Nesting.html - utils/haddock/html-test/ref/PatternSyns.html - + utils/haddock/html-test/ref/PatternSyns2.html - utils/haddock/html-test/ref/TitledPicture.html - utils/haddock/html-test/ref/TypeOperators.html - utils/haddock/html-test/ref/Unicode.html - utils/haddock/html-test/ref/Unicode2.html - + utils/haddock/html-test/src/PatternSyns2.hs - utils/haddock/latex-test/ref/LinearTypes/LinearTypes.tex - utils/hpc - utils/hsc2hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/fbca59fd30abaf4ce2412b3f880618… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/fbca59fd30abaf4ce2412b3f880618… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/T26709] 2 commits: Refactor srutOkForBinderSwap
by Simon Peyton Jones (＠simonpj) 31 Dec '25

31 Dec '25

Simon Peyton Jones pushed to branch wip/T26709 at Glasgow Haskell Compiler / GHC Commits: 45c8cc6d by Simon Peyton Jones at 2025-12-31T10:25:39+00:00 Refactor srutOkForBinderSwap This MR does a small refactor: * Moves `scrutOkForBinderSwap` and `BinderSwapDecision` to GHC.Core.Utils * Inverts the sense of the coercion it returns, which makes more sense No effect on behaviour - - - - - e091ab8d by Simon Peyton Jones at 2025-12-31T10:25:40+00:00 Improve case merging This small MR makes case merging happen a bit more often than it otherwise could, by getting join points out of the way. See #26709 and GHC.Core.Utils Note [Floating join points out of DEFAULT alternatives] - - - - - 8 changed files: - compiler/GHC/Core/Opt/OccurAnal.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Core/Opt/SpecConstr.hs - compiler/GHC/Core/Utils.hs - + testsuite/tests/simplCore/should_compile/T26709.hs - + testsuite/tests/simplCore/should_compile/T26709.stderr - testsuite/tests/simplCore/should_compile/all.T Changes: ===================================== compiler/GHC/Core/Opt/OccurAnal.hs ===================================== @@ -28,7 +28,7 @@ core expression with (hopefully) improved usage information. module GHC.Core.Opt.OccurAnal ( occurAnalysePgm, occurAnalyseExpr, - zapLambdaBndrs, BinderSwapDecision(..), scrutOkForBinderSwap + zapLambdaBndrs ) where import GHC.Prelude hiding ( head, init, last, tail ) @@ -36,7 +36,7 @@ import GHC.Prelude hiding ( head, init, last, tail ) import GHC.Core import GHC.Core.FVs import GHC.Core.Utils ( exprIsTrivial, isDefaultAlt, isExpandableApp, - mkCastMCo, mkTicks ) + mkCastMCo, mkTicks, BinderSwapDecision(..), scrutOkForBinderSwap ) import GHC.Core.Opt.Arity ( joinRhsArity, isOneShotBndr ) import GHC.Core.Coercion import GHC.Core.Type @@ -3537,6 +3537,7 @@ doesn't use it. So this is only to satisfy the perhaps-over-picky Lint. -} addBndrSwap :: OutExpr -> Id -> OccEnv -> OccEnv +-- See Note [Binder swap] -- See Note [The binder-swap substitution] addBndrSwap scrut case_bndr env@(OccEnv { occ_bs_env = swap_env, occ_bs_rng = rng_vars }) @@ -3544,7 +3545,7 @@ addBndrSwap scrut case_bndr , scrut_var /= case_bndr -- Consider: case x of x { ... } -- Do not add [x :-> x] to occ_bs_env, else lookupBndrSwap will loop - = env { occ_bs_env = extendVarEnv swap_env scrut_var (case_bndr', mco) + = env { occ_bs_env = extendVarEnv swap_env scrut_var (case_bndr', mkSymMCo mco) , occ_bs_rng = rng_vars `extendVarSet` case_bndr' `unionVarSet` tyCoVarsOfMCo mco } @@ -3554,27 +3555,6 @@ addBndrSwap scrut case_bndr case_bndr' = zapIdOccInfo case_bndr -- See Note [Zap case binders in proxy bindings] --- | See bBinderSwaOk. -data BinderSwapDecision - = NoBinderSwap - | DoBinderSwap OutVar MCoercion - -scrutOkForBinderSwap :: OutExpr -> BinderSwapDecision --- If (scrutOkForBinderSwap e = DoBinderSwap v mco, then --- v = e |> mco --- See Note [Case of cast] --- See Historical Note [Care with binder-swap on dictionaries] --- --- We use this same function in SpecConstr, and Simplify.Iteration, --- when something binder-swap-like is happening -scrutOkForBinderSwap e - = case e of - Tick _ e -> scrutOkForBinderSwap e -- Drop ticks - Var v -> DoBinderSwap v MRefl - Cast (Var v) co -> DoBinderSwap v (MCo (mkSymCo co)) - -- Cast: see Note [Case of cast] - _ -> NoBinderSwap - lookupBndrSwap :: OccEnv -> Id -> (CoreExpr, Id) -- See Note [The binder-swap substitution] -- Returns an expression of the same type as Id ===================================== compiler/GHC/Core/Opt/Simplify/Iteration.hs ===================================== @@ -22,7 +22,7 @@ import GHC.Core.TyCo.Compare( eqType ) import GHC.Core.Opt.Simplify.Env import GHC.Core.Opt.Simplify.Inline import GHC.Core.Opt.Simplify.Utils -import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr, zapLambdaBndrs, scrutOkForBinderSwap, BinderSwapDecision (..) ) +import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr, zapLambdaBndrs ) import GHC.Core.Make ( FloatBind, mkImpossibleExpr, castBottomExpr ) import qualified GHC.Core.Make import GHC.Core.Coercion hiding ( substCo, substCoVar ) @@ -3601,11 +3601,13 @@ addAltUnfoldings env case_bndr bndr_swap con_app env1 = addBinderUnfolding env case_bndr con_app_unf -- See Note [Add unfolding for scrutinee] + -- e.g. case (x |> co) of K a b -> blah + -- We add to `x` the unfolding (K a b |> sym co) env2 | DoBinderSwap v mco <- bndr_swap = addBinderUnfolding env1 v $ if isReflMCo mco -- isReflMCo: avoid calling mk_simple_unf then con_app_unf -- twice in the common case - else mk_simple_unf (mkCastMCo con_app mco) + else mk_simple_unf (mkCastMCo con_app (mkSymMCo mco)) | otherwise = env1 ===================================== compiler/GHC/Core/Opt/Simplify/Utils.hs ===================================== @@ -2693,7 +2693,7 @@ mkCase, mkCase1, mkCase2, mkCase3 mkCase mode scrut outer_bndr alts_ty alts | sm_case_merge mode - , Just (joins, alts') <- mergeCaseAlts outer_bndr alts + , Just (joins, alts') <- mergeCaseAlts scrut outer_bndr alts = do { tick (CaseMerge outer_bndr) ; case_expr <- mkCase1 mode scrut outer_bndr alts_ty alts' ; return (mkLets joins case_expr) } ===================================== compiler/GHC/Core/Opt/SpecConstr.hs ===================================== @@ -29,7 +29,6 @@ import GHC.Core.Opt.Simplify.Inline import GHC.Core.FVs ( exprsFreeVarsList, exprFreeVars ) import GHC.Core.Opt.Monad import GHC.Core.Opt.WorkWrap.Utils -import GHC.Core.Opt.OccurAnal( BinderSwapDecision(..), scrutOkForBinderSwap ) import GHC.Core.DataCon import GHC.Core.Class( classTyVars ) import GHC.Core.Coercion hiding( substCo ) ===================================== compiler/GHC/Core/Utils.hs ===================================== @@ -19,6 +19,7 @@ module GHC.Core.Utils ( mergeAlts, mergeCaseAlts, trimConArgs, filterAlts, combineIdenticalAlts, refineDefaultAlt, scaleAltsBy, + BinderSwapDecision(..), scrutOkForBinderSwap, -- * Properties of expressions exprType, coreAltType, coreAltsType, @@ -72,7 +73,7 @@ import GHC.Platform import GHC.Core import GHC.Core.Ppr -import GHC.Core.FVs( bindFreeVars ) +import GHC.Core.FVs( exprFreeVars, bindFreeVars ) import GHC.Core.DataCon import GHC.Core.Type as Type import GHC.Core.Predicate( isEqPred ) @@ -112,11 +113,11 @@ import GHC.Utils.Outputable import GHC.Utils.Panic import GHC.Utils.Misc +import Control.Monad ( guard ) import Data.ByteString ( ByteString ) import Data.Function ( on ) import Data.List ( sort, sortBy, partition, zipWith4, mapAccumL ) import Data.Ord ( comparing ) -import Control.Monad ( guard ) import qualified Data.Set as Set {- @@ -590,6 +591,28 @@ The default alternative must be first, if it exists at all. This makes it easy to find, though it makes matching marginally harder. -} +data BinderSwapDecision + = NoBinderSwap + | DoBinderSwap OutVar MCoercion + +scrutOkForBinderSwap :: OutExpr -> BinderSwapDecision +-- If (scrutOkForBinderSwap e = DoBinderSwap v mco, then +-- e = v |> mco +-- See Note [Case of cast] +-- See Historical Note [Care with binder-swap on dictionaries] +-- +-- We use this same function in SpecConstr, and Simplify.Iteration, +-- when something binder-swap-like is happening +-- +-- See Note [Binder swap] in GHC.Core.Opt.OccurAnal +scrutOkForBinderSwap e + = case e of + Tick _ e -> scrutOkForBinderSwap e -- Drop ticks + Var v -> DoBinderSwap v MRefl + Cast (Var v) co -> DoBinderSwap v (MCo co) + -- Cast: see Note [Case of cast] + _ -> NoBinderSwap + -- | Extract the default case alternative findDefault :: [Alt b] -> ([Alt b], Maybe (Expr b)) findDefault (Alt DEFAULT args rhs : alts) = assert (null args) (alts, Just rhs) @@ -651,11 +674,12 @@ filters down the matching alternatives in GHC.Core.Opt.Simplify.rebuildCase. -} --------------------------------- -mergeCaseAlts :: Id -> [CoreAlt] -> Maybe ([CoreBind], [CoreAlt]) +mergeCaseAlts :: CoreExpr -> Id -> [CoreAlt] -> Maybe ([CoreBind], [CoreAlt]) -- See Note [Merge Nested Cases] -mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) +mergeCaseAlts scrut outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) | Just (joins, inner_alts) <- go deflt_rhs - = Just (joins, mergeAlts outer_alts inner_alts) + , Just aux_binds <- mk_aux_binds joins + = Just ( aux_binds ++ joins, mergeAlts outer_alts inner_alts ) -- NB: mergeAlts gives priority to the left -- case x of -- A -> e1 @@ -665,6 +689,20 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) -- When we merge, we must ensure that e1 takes -- precedence over e2 as the value for A! where + scrut_fvs = exprFreeVars scrut + + -- See Note [Floating join points out of DEFAULT alternatives] + mk_aux_binds join_binds + | not (any mentions_outer_bndr join_binds) + = Just [] -- Good! No auxiliary bindings needed + | exprIsTrivial scrut + , not (outer_bndr `elemVarSet` scrut_fvs) + = Just [NonRec outer_bndr scrut] -- Need a fixup binding + | otherwise + = Nothing -- Can't do it + + mentions_outer_bndr bind = outer_bndr `elemVarSet` bindFreeVars bind + go :: CoreExpr -> Maybe ([CoreBind], [CoreAlt]) -- Whizzo: we can merge! @@ -702,11 +740,10 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) = do { (joins, alts) <- go body -- Check for capture; but only if we could otherwise do a merge - ; let capture = outer_bndr `elem` bindersOf bind - || outer_bndr `elemVarSet` bindFreeVars bind - ; guard (not capture) + -- (i.e. the recursive `go` succeeds) + ; guard (okToFloatJoin scrut_fvs outer_bndr bind) - ; return (bind:joins, alts ) } + ; return (bind : joins, alts ) } | otherwise = Nothing @@ -718,7 +755,18 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) go _ = Nothing -mergeCaseAlts _ _ = Nothing +mergeCaseAlts _ _ _ = Nothing + +okToFloatJoin :: VarSet -> Id -> CoreBind -> Bool +-- Check a join-point binding to see if it can be floated out of +-- the DEFAULT branch of a `case`. +-- See Note [Floating join points out of DEFAULT alternatives] +okToFloatJoin scrut_fvs outer_bndr bind + = not (any bad_bndr (bindersOf bind)) + where + bad_bndr bndr = bndr == outer_bndr -- (a) + || bndr `elemVarSet` scrut_fvs -- (b) + --------------------------------- mergeAlts :: [Alt a] -> [Alt a] -> [Alt a] @@ -927,10 +975,46 @@ Wrinkles non-join-points unless the /outer/ case has just one alternative; doing so would risk more allocation + Floating out join points isn't entirely straightforward. + See Note [Floating join points out of DEFAULT alternatives] + (MC5) See Note [Cascading case merge] See also Note [Example of case-merging and caseRules] in GHC.Core.Opt.Simplify.Utils +Note [Floating join points out of DEFAULT alternatives] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Consider this, from (MC4) of Note [Merge Nested Cases] + case x of r + DEFAULT -> join j = rhs in case r of ... + alts + +We want to float that join point out to give this + join j = rhs + case x of r + DEFAULT -> case r of ... + alts + +But doing so is flat-out wrong if the scoping gets messed up: + (a) case x of r { DEFAULT -> join r = ... in ...r... } + (b) case j of r { DEFAULT -> join j = ... in ... } + (c) case x of r { DEFAULT -> join j = ...r.. in ... } +In all these cases we can't float the join point out because r changes its +meaning. For (a) and (b) the Simplifier removes shadowing, so they'll +be solved in the next iteration. But case (c) will persist. + +Happily, we can fix up case (c) by adding an auxiliary binding, like this + let r = e in + join j = rhs[r] + case e of r + DEFAULT -> ...r... + ...other alts... + +We can only do this if + * We don't introduce shadowing: that is `j` and `r` do not appear free in `e`. + (Again the Simplifier will eliminate such shadowing.) + * The scrutinee `e` is trivial so that the transformation doesn't duplicate work. + Note [Cascading case merge] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ===================================== testsuite/tests/simplCore/should_compile/T26709.hs ===================================== @@ -0,0 +1,11 @@ +module T26709 where + +data T = A | B | C + +f x = case x of + A -> True + _ -> let {-# NOINLINE j #-} + j y = y && not (f x) + in case x of + B -> j True + C -> j False ===================================== testsuite/tests/simplCore/should_compile/T26709.stderr ===================================== @@ -0,0 +1,32 @@ +[1 of 1] Compiling T26709 ( T26709.hs, T26709.o ) + +==================== Tidy Core ==================== +Result size of Tidy Core + = {terms: 26, types: 9, coercions: 0, joins: 1/1} + +Rec { +-- RHS size: {terms: 25, types: 7, coercions: 0, joins: 1/1} +f [Occ=LoopBreaker] :: T -> Bool +[GblId, Arity=1, Str=<SL>, Unf=OtherCon []] +f = \ (x :: T) -> + join { + j [InlPrag=NOINLINE, Dmd=MC(1,L)] :: Bool -> Bool + [LclId[JoinId(1)(Just [!])], Arity=1, Str=<1L>, Unf=OtherCon []] + j (eta [OS=OneShot] :: Bool) + = case eta of { + False -> GHC.Internal.Types.False; + True -> + case f x of { + False -> GHC.Internal.Types.True; + True -> GHC.Internal.Types.False + } + } } in + case x of { + A -> GHC.Internal.Types.True; + B -> jump j GHC.Internal.Types.True; + C -> jump j GHC.Internal.Types.False + } +end Rec } + + + ===================================== testsuite/tests/simplCore/should_compile/all.T ===================================== @@ -563,3 +563,8 @@ test('T26115', [grep_errmsg(r'DFun')], compile, ['-O -ddump-simpl -dsuppress-uni test('T26116', normal, compile, ['-O -ddump-rules']) test('T26117', [grep_errmsg(r'==')], compile, ['-O -ddump-simpl -dsuppress-uniques']) test('T26349', normal, compile, ['-O -ddump-rules']) + +# T26709: we expect three `case` expressions not four +test('T26709', [grep_errmsg(r'case')], + multimod_compile, + ['T26709', '-O -ddump-simpl -dsuppress-uniques -dno-typeable-binds']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/1cb9b4d9713a833a4477649dfbd746… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/1cb9b4d9713a833a4477649dfbd746… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/spj-try-opt-coercion] More refactoring
by Simon Peyton Jones (＠simonpj) 31 Dec '25

31 Dec '25

Simon Peyton Jones pushed to branch wip/spj-try-opt-coercion at Glasgow Haskell Compiler / GHC Commits: 86d4cd86 by Simon Peyton Jones at 2025-12-31T10:22:11+00:00 More refactoring - - - - - 8 changed files: - compiler/GHC/Core/Coercion/Opt.hs - compiler/GHC/Core/Opt/Pipeline.hs - compiler/GHC/Core/Opt/Simplify/Env.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Core/SimpleOpt.hs - compiler/GHC/Driver/Config.hs - compiler/GHC/Driver/DynFlags.hs Changes: ===================================== compiler/GHC/Core/Coercion/Opt.hs ===================================== @@ -42,13 +42,32 @@ import Control.Monad ( zipWithM ) %* * %************************************************************************ +Note [Coercion optimisation] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This module does coercion optimisation. See the paper - Evidence normalization in Systtem FV (RTA'13) https://simon.peytonjones.org/evidence-normalization/ - The paper is also in the GHC repo, in docs/opt-coercion. +However, although powerful and occasionally very effective, coercion optimisation +can be very expensive (#26679). So we apply it sparingly: + +* In the Simplifier, function `rebuild_go`, we use `isReflexiveCo` (which + computes the type of the coercion) to eliminate reflexive coercion, just + before we build a cast (e |> co). + + (More precisely, we use `isReflexiveCoIgnoringMultiplicity.) + +* We have a whole pass, `optCoProgram` that runs the coercion optimiser on all + the coercions in the program. + + - We run it once in all optimisation levels + (see GHC.Driver.DynFlags.optLevelFlags) + + - We run it early in the optimisation pipeline + (see GHC.Core.Opt.Pipeline.getCoreToDo). + + Note [Optimising coercion optimisation] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Looking up a coercion's role or kind is linear in the size of the ===================================== compiler/GHC/Core/Opt/Pipeline.hs ===================================== @@ -227,6 +227,7 @@ getCoreToDo dflags hpt_rule_base extra_vars -- Optimise coercions -- With -O do this after one run of the Simplifier. -- Without -O, just take what the desugarer produced + -- See Note [Coercion optimisation] in GHC.Core.Coercion.Opt runWhen do_co_opt CoreOptCoercion, if full_laziness then ===================================== compiler/GHC/Core/Opt/Simplify/Env.hs ===================================== @@ -161,15 +161,16 @@ following table: Note [Inline depth] ~~~~~~~~~~~~~~~~~~~ +The seInlineDepth tells us how deep in inlining we are. + When we inline an /already-simplified/ unfolding, we * Zap the substitution environment; the inlined thing is an OutExpr * Bump the seInlineDepth in the SimplEnv Both these tasks are done in zapSubstEnv. -The seInlineDepth tells us how deep in inlining we are. Currently, -seInlineDepth is used for just one purpose: when we encounter a -coercion we don't apply optCoercion to it if seInlineDepth>0. -Reason: it has already been optimised once, no point in doing so again. +Currently, `seInlineDepth` is entirely unused! (It was previously used to avoid +repeatedly optimising coercions.) But it's cheap to maintain and might prove +useful, so I have no removed it. -} data SimplEnv ===================================== compiler/GHC/Core/Opt/Simplify/Iteration.hs ===================================== @@ -27,7 +27,6 @@ import GHC.Core.Make ( FloatBind, mkImpossibleExpr, castBottomExpr ) import qualified GHC.Core.Make import GHC.Core.Coercion hiding ( substCo, substCoVar ) import GHC.Core.Reduction -import GHC.Core.Coercion.Opt ( optCoercion ) import GHC.Core.FamInstEnv ( FamInstEnv, topNormaliseType_maybe ) import GHC.Core.DataCon import GHC.Core.Opt.Stats ( Tick(..) ) @@ -1358,16 +1357,8 @@ simplCoercionF env co cont simplCoercion :: SimplEnv -> InCoercion -> SimplM OutCoercion simplCoercion env co - = do { let opt_co | reSimplifying env = substCo env co - | otherwise = optCoercion opts subst co - -- If (reSimplifying env) is True we have already simplified - -- this coercion once, and we don't want do so again; doing - -- so repeatedly risks non-linear behaviour - -- See Note [Inline depth] in GHC.Core.Opt.Simplify.Env - ; seqCo opt_co `seq` return opt_co } - where - subst = getTCvSubst env - opts = seOptCoercionOpts env + = do { let out_co = substCo env co + ; seqCo out_co `seq` return out_co } ----------------------------------- -- | Push a TickIt context outwards past applications and cases, as @@ -1538,15 +1529,13 @@ rebuild_go env expr cont case cont of Stop {} -> return (emptyFloats env, expr) TickIt t cont -> rebuild_go env (mkTick t expr) cont - CastIt { sc_co = co, sc_opt = opt, sc_cont = cont } + CastIt { sc_co = co, sc_cont = cont } | isReflexiveCoIgnoringMultiplicity co -- ignoring multiplicity: c.f. GHC.Core.Coercion.Opt.opt_univ -> rebuild_go env expr cont | otherwise - -> rebuild_go env (mkCast expr co') cont + -> rebuild_go env (mkCast expr co) cont -- NB: mkCast implements the (Coercion co |> g) optimisation - where - co' = optOutCoercion env co opt Select { sc_bndr = bndr, sc_alts = alts, sc_env = se, sc_cont = cont } -> rebuildCase (se `setInScopeFromE` env) expr bndr alts cont @@ -1645,45 +1634,9 @@ isReflexiveCo In investigating this I saw missed opportunities for on-the-fly coercion shrinkage. See #15090. - -Note [Avoid re-simplifying coercions] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -In some benchmarks (with deeply nested cases) we successively push -casts onto the SimplCont. We don't want to call the coercion optimiser -on each successive composition -- that's at least quadratic. So: - -* The CastIt constructor in SimplCont has a `sc_opt :: Bool` flag to - record whether the coercion optimiser has been applied to the coercion. - -* In `simplCast`, when we see (Cast e co), we simplify `co` to get - an OutCoercion, and built a CastIt with sc_opt=True. - - Actually not quite: if we are simplifying the result of inlining an - unfolding (seInlineDepth > 0), then instead of /optimising/ it again, - just /substitute/ which is cheaper. See `simplCoercion`. - -* In `addCoerce` (in `simplCast`) if we combine this new coercion with - an existing once, we build a CastIt for (co1 ; co2) with sc_opt=False. - -* When unpacking a CastIt, in `rebuildCall` and `rebuild`, we optimise - the (presumably composed) coercion if sc_opt=False; this is done - by `optOutCoercion`. - -* When duplicating a continuation in `mkDupableContWithDmds`, before - duplicating a CastIt, optimise the coercion. Otherwise we'll end up - optimising it separately in the duplicate copies. -} -optOutCoercion :: SimplEnvIS -> OutCoercion -> Bool -> OutCoercion --- See Note [Avoid re-simplifying coercions] -optOutCoercion env co already_optimised - | already_optimised = co -- See Note [Avoid re-simplifying coercions] - | otherwise = optCoercion opts empty_subst co - where - empty_subst = mkEmptySubst (seInScope env) - opts = seOptCoercionOpts env - simplCast :: SimplEnv -> InExpr -> InCoercion -> SimplCont -> SimplM (SimplFloats, OutExpr) simplCast env body co0 cont0 @@ -1691,27 +1644,25 @@ simplCast env body co0 cont0 ; cont1 <- {-#SCC "simplCast-addCoerce" #-} if isReflCo co1 then return cont0 -- See Note [Optimising reflexivity] - else addCoerce co1 True cont0 - -- True <=> co1 is optimised + else addCoerce co1 cont0 ; {-#SCC "simplCast-simplExprF" #-} simplExprF env body cont1 } where - -- If the first parameter is MRefl, then simplifying revealed a -- reflexive coercion. Omit. - addCoerceM :: MOutCoercion -> Bool -> SimplCont -> SimplM SimplCont - addCoerceM MRefl _ cont = return cont - addCoerceM (MCo co) opt cont = addCoerce co opt cont + addCoerceM :: MOutCoercion -> SimplCont -> SimplM SimplCont + addCoerceM MRefl cont = return cont + addCoerceM (MCo co) cont = addCoerce co cont - addCoerce :: OutCoercion -> Bool -> SimplCont -> SimplM SimplCont - addCoerce co1 _ (CastIt { sc_co = co2, sc_cont = cont }) -- See Note [Optimising reflexivity] - = addCoerce (mkTransCo co1 co2) False cont + addCoerce :: OutCoercion -> SimplCont -> SimplM SimplCont + addCoerce co1 (CastIt { sc_co = co2, sc_cont = cont }) -- See Note [Optimising reflexivity] + = addCoerce (mkTransCo co1 co2) cont -- False: (mkTransCo co1 co2) is not fully optimised -- See Note [Avoid re-simplifying coercions] - addCoerce co co_is_opt (ApplyToTy { sc_arg_ty = arg_ty, sc_cont = tail }) + addCoerce co (ApplyToTy { sc_arg_ty = arg_ty, sc_cont = tail }) | Just (arg_ty', m_co') <- pushCoTyArg co arg_ty = {-#SCC "addCoerce-pushCoTyArg" #-} - do { tail' <- addCoerceM m_co' co_is_opt tail + do { tail' <- addCoerceM m_co' tail ; return (ApplyToTy { sc_arg_ty = arg_ty' , sc_cont = tail' , sc_hole_ty = coercionLKind co }) } @@ -1721,15 +1672,12 @@ simplCast env body co0 cont0 -- where co :: (s1->s2) ~ (t1->t2) -- co1 :: t1 ~ s1 -- co2 :: s2 ~ t2 - addCoerce co co_is_opt cont@(ApplyToVal { sc_arg = arg, sc_env = arg_se - , sc_dup = dup, sc_cont = tail - , sc_hole_ty = fun_ty }) - | not co_is_opt -- pushCoValArg duplicates the coercion, so optimise first - = addCoerce (optOutCoercion (zapSubstEnv env) co co_is_opt) True cont - + addCoerce co cont@(ApplyToVal { sc_arg = arg, sc_env = arg_se + , sc_dup = dup, sc_cont = tail + , sc_hole_ty = fun_ty }) | Just (m_co1, m_co2) <- pushCoValArg co = {-#SCC "addCoerce-pushCoValArg" #-} - do { tail' <- addCoerceM m_co2 co_is_opt tail + do { tail' <- addCoerceM m_co2 tail ; case m_co1 of { MRefl -> return (cont { sc_cont = tail' , sc_hole_ty = coercionLKind co }) ; @@ -1748,11 +1696,11 @@ simplCast env body co0 cont0 , sc_cont = tail' , sc_hole_ty = coercionLKind co }) } } } - addCoerce co co_is_opt cont + addCoerce co cont | isReflCo co = return cont -- Having this at the end makes a huge -- difference in T12227, for some reason -- See Note [Optimising reflexivity] - | otherwise = return (CastIt { sc_co = co, sc_opt = co_is_opt, sc_cont = cont }) + | otherwise = return (CastIt { sc_co = co, sc_cont = cont }) simplLazyArg :: SimplEnvIS -- ^ Used only for its InScopeSet -> DupFlag @@ -3877,11 +3825,9 @@ mkDupableContWithDmds env _ cont mkDupableContWithDmds _ _ (Stop {}) = panic "mkDupableCont" -- Handled by previous eqn -mkDupableContWithDmds env dmds (CastIt { sc_co = co, sc_opt = opt, sc_cont = cont }) +mkDupableContWithDmds env dmds (CastIt { sc_co = co, sc_cont = cont }) = do { (floats, cont') <- mkDupableContWithDmds env dmds cont - ; return (floats, CastIt { sc_co = optOutCoercion env co opt - , sc_opt = True, sc_cont = cont' }) } - -- optOutCoercion: see Note [Avoid re-simplifying coercions] + ; return (floats, CastIt { sc_co = co, sc_cont = cont' }) } -- Duplicating ticks for now, not sure if this is good or not mkDupableContWithDmds env dmds (TickIt t cont) ===================================== compiler/GHC/Core/Opt/Simplify/Utils.hs ===================================== @@ -164,9 +164,6 @@ data SimplCont | CastIt -- (CastIt co K)[e] = K[ e `cast` co ] { sc_co :: OutCoercion -- The coercion simplified -- Invariant: never an identity coercion - , sc_opt :: Bool -- True <=> sc_co has had optCoercion applied to it - -- See Note [Avoid re-simplifying coercions] - -- in GHC.Core.Opt.Simplify.Iteration , sc_cont :: SimplCont } | ApplyToVal -- (ApplyToVal arg K)[e] = K[ e arg ] ===================================== compiler/GHC/Core/SimpleOpt.hs ===================================== @@ -30,7 +30,6 @@ import GHC.Core.Unfold.Make import GHC.Core.Make ( FloatBind(..), mkWildValBinder ) import GHC.Core.Opt.OccurAnal( occurAnalyseExpr, occurAnalysePgm, zapLambdaBndrs ) import GHC.Core.DataCon -import GHC.Core.Coercion.Opt ( optCoercion, OptCoercionOpts (..) ) import GHC.Core.Type hiding ( substTy, extendTvSubst, extendCvSubst, extendTvSubstList , isInScope, substTyVarBndr, cloneTyVarBndr ) import GHC.Core.Predicate( isCoVarType ) @@ -113,7 +112,6 @@ See ticket #25790 -- | Simple optimiser options data SimpleOpts = SimpleOpts { so_uf_opts :: !UnfoldingOpts -- ^ Unfolding options - , so_co_opts :: !OptCoercionOpts -- ^ Coercion optimiser options , so_eta_red :: !Bool -- ^ Eta reduction on? , so_inline :: !Bool -- ^ False <=> do no inlining whatsoever, -- even for trivial or used-once things @@ -123,7 +121,6 @@ data SimpleOpts = SimpleOpts defaultSimpleOpts :: SimpleOpts defaultSimpleOpts = SimpleOpts { so_uf_opts = defaultUnfoldingOpts - , so_co_opts = OptCoercionOpts { optCoercionEnabled = False } , so_eta_red = False , so_inline = True } @@ -288,7 +285,7 @@ simple_opt_expr env expr = go expr go e@(Lam {}) = simple_app env e [] go (Type ty) = Type (substTyUnchecked subst ty) - go (Coercion co) = Coercion (go_co co) + go (Coercion co) = Coercion (simple_opt_co env co) go (Lit lit) = Lit lit go (Tick tickish e) = mkTick (substTickish subst tickish) (go e) go (Let bind body) = case simple_opt_bind env bind NotTopLevel of @@ -323,15 +320,15 @@ simple_opt_expr env expr = go expr e' = go e (env', b') = subst_opt_bndr env b - ---------------------- - go_co co = optCoercion (so_co_opts (soe_opts env)) subst co - ---------------------- go_alt env (Alt con bndrs rhs) = Alt con bndrs' (simple_opt_expr env' rhs) where (env', bndrs') = subst_opt_bndrs env bndrs +simple_opt_co :: SimpleOptEnv -> InCoercion -> OutCoercion +simple_opt_co env co = substCo (soe_subst env) co + mk_cast :: CoreExpr -> CoercionR -> CoreExpr -- Like GHC.Core.Utils.mkCast, but does a full reflexivity check. -- mkCast doesn't do that because the Simplifier does (in simplCast) @@ -471,7 +468,7 @@ add_cast env co1 as CastIt co2:rest -> CastIt (co1' `mkTransCo` co2):rest _ -> CastIt co1':as where - co1' = optCoercion (so_co_opts (soe_opts env)) (soe_subst env) co1 + co1' = simple_opt_co env co1 rebuild_app :: HasDebugCallStack => SimpleOptEnv -> OutExpr -> [SimpleContItem] -> OutExpr @@ -606,7 +603,7 @@ simple_bind_pair env@(SOE { soe_inl = inl_env, soe_subst = subst, soe_opts = opt (env { soe_subst = extendTvSubst subst in_bndr out_ty }, Nothing) | Coercion co <- in_rhs - , let out_co = optCoercion (so_co_opts (soe_opts env)) (soe_subst rhs_env) co + , let out_co = simple_opt_co rhs_env co = assert (isCoVar in_bndr) (env { soe_subst = extendCvSubst subst in_bndr out_co }, Nothing) ===================================== compiler/GHC/Driver/Config.hs ===================================== @@ -24,7 +24,6 @@ initOptCoercionOpts dflags = OptCoercionOpts initSimpleOpts :: DynFlags -> SimpleOpts initSimpleOpts dflags = SimpleOpts { so_uf_opts = unfoldingOpts dflags - , so_co_opts = initOptCoercionOpts dflags , so_eta_red = gopt Opt_DoEtaReduction dflags , so_inline = True } ===================================== compiler/GHC/Driver/DynFlags.hs ===================================== @@ -1236,7 +1236,7 @@ optLevelFlags -- see Note [Documenting optimisation flags] , ([1,2], Opt_DoCleverArgEtaExpansion) -- See Note [Eta expansion of arguments in CorePrep] , ([0,1,2], Opt_DoEtaReduction) -- See Note [Eta-reduction in -O0] , ([0,1,2], Opt_ProfManualCcs ) - , ([0,1,2], Opt_OptCoercion ) + , ([0,1,2], Opt_OptCoercion ) -- See Note [Coercion optimisation] in GHC.Core.Coercion.Opt , ([2], Opt_DictsStrict) , ([0], Opt_IgnoreInterfacePragmas) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/86d4cd861572e6a901098a7fc6ea77d… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/86d4cd861572e6a901098a7fc6ea77d… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/spj-try-opt-coercion] 63 commits: compiler: remove unused CPP code in foreign stub
by Simon Peyton Jones (＠simonpj) 31 Dec '25

31 Dec '25

Simon Peyton Jones pushed to branch wip/spj-try-opt-coercion at Glasgow Haskell Compiler / GHC Commits: d99f8326 by Cheng Shao at 2025-12-11T19:14:18-05:00 compiler: remove unused CPP code in foreign stub This patch removes unused CPP code in the generated foreign stub: - `#define IN_STG_CODE 0` is not needed, since `Rts.h` already includes this definition - The `if defined(__cplusplus)` code paths are not needed in the `.c` file, since we don't generate C++ stubs and don't include C++ headers in our stubs. But it still needs to be present in the `.h` header since it might be later included into C++ source files. - - - - - 46c9746f by Cheng Shao at 2025-12-11T19:14:57-05:00 configure: bump LlvmMaxVersion to 22 This commit bumps LlvmMaxVersion to 22; 21.x releases have been available since Aug 26th, 2025 and there's no regressions with 21.x so far. This bump is also required for updating fedora image to 43. - - - - - 96fce8d0 by Cheng Shao at 2025-12-12T01:17:51+01:00 hadrian: add support for building with UndefinedBehaviorSanitizer This patch adds a +ubsan flavour transformer to hadrian to build all stage1+ C/C++ code with UndefinedBehaviorSanitizer. This is particularly useful to catch potential undefined behavior in the RTS codebase. - - - - - f7a06d8c by Cheng Shao at 2025-12-12T01:17:51+01:00 ci: update alpine/fedora & add ubsan job This patch updates alpine image to 3.23, fedora image to 43, and adds a `x86_64-linux-fedora43-validate+debug_info+ubsan` job that's run in validate/nightly pipelines to catch undefined behavior in the RTS codebase. - - - - - 2ccd11ca by Cheng Shao at 2025-12-12T01:17:51+01:00 rts: fix zero-length VLA undefined behavior in interpretBCO This commit fixes a zero-length VLA undefined behavior in interpretBCO, caught by UBSan: ``` +rts/Interpreter.c:3133:19: runtime variable length array bound evaluates to non-positive value 0 ``` - - - - - 4156ed19 by Cheng Shao at 2025-12-12T01:17:51+01:00 rts: fix unaligned ReadSpB in interpretBCO This commit fixes unaligned ReadSpB in interpretBCO, caught by UBSan: ``` +rts/Interpreter.c:2174:64: runtime load of misaligned address 0x004202059dd1 for type 'StgWord', which requires 8 byte alignment ``` To perform proper unaligned read, we define StgUnalignedWord as a type alias of StgWord with aligned(1) attribute, and load StgUnalignedWord instead of StgWord in ReadSpB, so the C compiler is aware that we're not loading with natural alignment. - - - - - fef89fb9 by Cheng Shao at 2025-12-12T01:17:51+01:00 rts: fix signed integer overflow in subword arithmetic in interpretBCO This commit fixes signed integer overflow in subword arithmetic in interpretBCO, see added note for detailed explanation. - - - - - 3c001377 by Cheng Shao at 2025-12-13T05:03:15-05:00 ci: use treeless fetch for perf notes This patch improves the ci logic for fetching perf notes by using treeless fetch (https://github.blog/open-source/git/get-up-to-speed-with-partial-clone-and-…) to avoid downloading all blobs of the perf notes repo at once, and only fetch the actually required blobs on-demand when needed. This makes the initial `test-metrics.sh pull` operation much faster, and also more robust, since we are seeing an increasing rate of 504 errors in CI when fetching all perf notes at once, which is a major source of CI flakiness at this point. Co-authored-by: Codex <codex(a)openai.com> - - - - - 123a8d77 by Peter Trommler at 2025-12-13T05:03:57-05:00 Cmm: remove restriction in MachOp folding - - - - - 0b54b5fd by Andreas Klebinger at 2025-12-13T05:04:38-05:00 Remove explicit Typeable deriviations. - - - - - 08b13f7b by Cheng Shao at 2025-12-13T05:05:18-05:00 ci: set gc.auto=0 during setup stage This patch sets `gc.auto=0` during `setup` stage of CI, see added comment for detailed explanation. - - - - - 3b5aecb5 by Ben Gamari at 2025-12-13T23:43:10+01:00 Bump exceptions submodule to 0.10.11 - - - - - c32de3b0 by Johan Förberg at 2025-12-15T02:36:03-05:00 base: Define Semigroup and Monoid instances for lazy ST CLC proposal: https://github.com/haskell/core-libraries-committee/issues/374 Fixes #26581 - - - - - 4f8b660c by mangoiv at 2025-12-15T02:37:05-05:00 ci: do not require nightly cabal-reinstall job to succeed - - - - - 2c2a3ef3 by Cheng Shao at 2025-12-15T11:51:53-05:00 docs: drop obsolete warning about -fexternal-interpreter on windows This patch drops an obsolete warning about -fexternal-interpreter not supported on windows; it is supported since a long time ago, including the profiled way. - - - - - 68573aa5 by Marc Scholten at 2025-12-15T11:53:00-05:00 haddock: Drop Haddock.Backends.HaddockDB as it's unused - - - - - b230d549 by mangoiv at 2025-12-16T15:17:45-05:00 base: generalize delete{Firsts,}By When we delete{Firsts,}By we should not require the lists to be the same type. This is an especially useful generalisation in the case of deleteFirstsBy because we can skip an invocation of the map function. This change was discussed on the core-libraries-committee's bug tracker at https://github.com/haskell/core-libraries-committee/issues/372. - - - - - 6a2b43e3 by Cheng Shao at 2025-12-16T15:18:30-05:00 compiler: clean up redundant LANGUAGE pragmas This patch bumps `default-language` of `ghc`/`ghc-bin` from `GHC2021` to `GHC2024` (which is supported in ghc 9.10, current boot ghc lower version bound), and also cleans up redundant `LANGUAGE` pragmas (as well as `default-extensions`/`other-extensions`) that are already implied by `GHC2024`. Co-authored-by: Codex <codex(a)openai.com> - - - - - fca9cd7c by sheaf at 2025-12-18T13:18:18-05:00 X86 CodeGen: fix assign_eax_sse_regs We must set %al to the number of SSE2 registers that contain arguments (in case we are dealing with a varargs function). The logic for counting how many arguments reside in SSE2 registers was incorrect, as it used 'isFloatFormat', which incorrectly ignores vector registers. We now instead do case analysis on the register class: is_sse_reg r = case targetClassOfReg platform r of RcFloatOrVector -> True RcInteger -> False This change is necessary to prevent segfaults in T20030_test1j, because subsequent commits change the format calculations, resulting in vector formats more often. - - - - - 53150617 by sheaf at 2025-12-18T13:18:19-05:00 X86 regUsageOfInstr: fix format for IMUL When used with 8-bit operands, the IMUL instruction returns the result in the lower 16 bits of %rax (also known as %ax). This is different than for the other sizes, where an input at 16, 32 or 64 bits will result in 16, 32 or 64 bits of output in both %rax and %rdx. This doesn't affect the behaviour of the compiler, because we don't allow partial writes at sub-word sizes. The rationale is explained in Wrinkle [Don't allow scalar partial writes] in Note [Register formats in liveness analysis], in GHC.CmmToAsm.Reg.Liveness. - - - - - c7a56dd1 by sheaf at 2025-12-18T13:18:19-05:00 Liveness analysis: consider register formats This commit updates the register allocator to be a bit more careful in situations in which a single register is used at multiple different formats, e.g. when xmm1 is used both to store a Double# and a DoubleX2#. This is done by introducing the 'Regs' newtype around 'UniqSet RegWithFormat', for which the combining operations take the larger of the two formats instead of overriding the format. Operations on 'Regs' are defined in 'GHC.CmmToAsm.Reg.Regs'. There is a modest compile-time cost for the additional overhead for tracking register formats, which causes the metric increases of this commit. The subtle aspects of the implementation are outlined in Note [Register formats in liveness analysis] in GHC.CmmToAsm.Reg.Liveness. Fixes #26411 #26611 ------------------------- Metric Increase: T12707 T26425 T3294 ------------------------- - - - - - c2e83339 by sheaf at 2025-12-18T13:18:19-05:00 Register allocator: reload at same format as spill This commit ensures that if we spill a register onto the stack at a given format, we then always reload the register at this same format. This ensures we don't end up in a situation where we spill F64x2 but end up only reloading the lower F64. This first reload would make us believe the whole data is in a register, thus silently losing the upper 64 bits of the spilled register's contents. Fixes #26526 - - - - - 55ab583b by sheaf at 2025-12-18T13:18:19-05:00 Register allocation: writes redefine format As explained in Note [Allocated register formats] in GHC.CmmToAsm.Reg.Linear, we consider all writes to redefine the format of the register. This ensures that in a situation such as movsd .Ln6m(%rip),%v1 shufpd $0,%v1,%v1 we properly consider the broadcast operation to change the format of %v1 from F64 to F64x2. This completes the fix to #26411 (test in T26411b). - - - - - 951402ed by Vladislav Zavialov at 2025-12-18T13:19:05-05:00 Parser: improve mkModuleImpExp, remove checkImportSpec 1. The `mkModuleImpExp` helper now knows whether it is processing an import or export list item, and uses this information to produce a more accurate error message for `import M (T(..,x))` with PatternSynonyms disabled. The old message incorrectly referred to this case as an export form. 2. The `checkImportSpec` helper is removed in favor of more comprehensive error checking in `mkModuleImpExp`. 3. Additionaly, the invariants of `ImpExpList` and `ImpExpAllWith` have been made more explicit in the comments and assertions (calls to 'panic'). Test case: import-syntax-no-ext - - - - - 47d83d96 by Vladislav Zavialov at 2025-12-18T13:19:06-05:00 Subordinate namespace-specified wildcards (#25901) Add support for subordinate namespace-specified wildcards `X(type ..)` and `X(data ..)` to import and export lists. Examples: import M (Cls(type ..)) -- imports Cls and all its associated types import M (Cls(data ..)) -- imports Cls and all its methods module M (R(data ..), C(type ..)) where -- exports R and all its data constructors and record fields; -- exports C and all its associated types, but not its methods The scope of this change is limited to the case where the wildcard is the only subordinate import/export item, whereas the more complex forms `X(type .., f)` or `X(type .., data ..)` are unsupported and raise the newly introduced PsErrUnsupportedExplicitNamespace error. This restriction may be lifted later. Summary of the changes: 1. Refactor IEThingAll to store its extension field XIEThingAll as a record IEThingAllExt instead of a tuple. 2. Extend the AST by adding a NamespaceSpecifier field to IEThingAllExt, representing an optional namespace specifier `type` or `data` in front of a subordinate wildcard `X(..)`. 3. Extend the grammar in Parser.y with productions for `type ..` and `data ..` in subordinate import/export items. 4. Introduce `filterByNamespaceGREs` to filter [GlobalRdrElt] by a NamespaceSpecifier; use it in `filterImports` and `exports_from_avail` to account for the namespace specifier in IEThingAll. 5. Improve diagnostics by storing more information in DodgyImportsEmptyParent and DodgyExportsEmptyParent. Test cases: T25901_sub_e T25901_sub_f T25901_sub_g T25901_sub_a T25901_sub_b T25901_sub_c T25901_sub_d T25901_sub_w DodgyImports02 DodgyImports03 DodgyImports04 - - - - - eac418bb by Recursion Ninja at 2025-12-18T13:19:48-05:00 Removing the 'Data' instance for 'InstEnv'. The 'Data' instance is blocking work on Trees that Grow, and the 'Data' instance seem to have been added without a clear purpose. - - - - - e920e038 by Recursion Ninja at 2025-12-18T13:19:48-05:00 'Decouple Language.Haskell.Syntax.Decls' from 'GHC.Unit.Module.Warnings' - - - - - bd38b76c by Cheng Shao at 2025-12-18T13:20:31-05:00 testsuite: improve coverage of foundation test This patch refactors the `foundation` test a bit to improve coverage: - Instead of using a hard-coded seed, a random seed is now taken from the command line, and printed upon test failure. This improves test coverage over many future CI runs, and shall a failure occur, the seed is available in the CI log for local reproduction. - The iterations count is bumped to 1000 instead of 100, similar to the bump in `test-primops`. Runtime timeout is bumped 2x just to be safe. - Improve `newLCGGen` by using non-atomic loads/stores on a `MutableByteArray#` for storing mutable `Word64`, this test doesn't use parallelism in the first place - Fixed a few compiler warnings and removed redundant pragmas and imports Co-authored-by: Codex <codex(a)openai.com> - - - - - 3995187c by Sylvain Henry at 2025-12-18T13:21:45-05:00 Doc: document -pgmi "" (#26634) - - - - - 5729418c by Cheng Shao at 2025-12-18T13:22:29-05:00 rts: use __builtin_mul_overflow for hs_mulIntMayOflo This patch uses `__builtin_mul_overflow` to implement `hs_mulIntMayOflo`. This is a GNU C checked arithmetic builtin function supported by gcc/clang, is type-generic so works for both 32-bit/64-bit, and makes the code both more efficient and easier to read/maintain than the previous hand rolled logic. - - - - - 1ca4b49a by Cheng Shao at 2025-12-18T13:23:11-05:00 compiler/rts: fix ABI mismatch in barf() invocations This patch fixes a long-standing issue of ABI mismatch in `barf()` invocations, both in compiler-emitted code and in hand written Cmm code: - In RTS, we have `barf()` which reports a fatal internal error message and exits the program. - `barf()` is a variadic C function! When used as a callee of a foreign call with `ccall` calling convention instead of `capi`, there is an ABI mismatch between the caller and the callee! - Unfortunately, both the compiler and the Cmm sources contain many places where we call `barf()` via `ccall` convention!! Like, when you write `foreign "C" barf("foo object (%p) entered!", R1)`, it totally doesn't do what you think it'll do at all!! The second argument `R1` is not properly passed in `va_list`, and the behavior is completely undefined!! - Even more unfortunately, this issue has been sitting around long enough because the ABI mismatch is subtle enough on normie platforms like x64 and arm64. - But there are platforms like wasm32 that are stricter about ABI, and the broken `barf()` invocations already causes trouble for wasm backend: we had to use ugly hacks like `barf(errmsg, NULL)` to make `wasm-ld` happy, and even with this band-aid, compiler-generated `barf()` invocations are still broken, resulting in regressions in certain debug-related functionality, e.g. `-dtag-inference-checks` is broken on wasm32 (#22882). This patch properly fixes the issue: - We add non-variadic `barf` wrappers in the RTS that can be used as `ccall` callees - Both the compiler `emitBarf` logic and the hand-written Cmm are changed to call these wrappers - `emitBarf` now also properly annotates the foreign call as `CmmNeverReturns` to indicate it's a noreturn call to enable more efficient code generation `-dtag-inference-checks` now works on wasm. Closes #22882. Co-authored-by: Codex <codex(a)openai.com> - - - - - b3dd23b9 by Vilim Lendvaj at 2025-12-18T13:23:57-05:00 Remove outdated comment The Traversable instance for ZipList is no longer in GHC.Internal.Data.Traversable. In fact, it is right below this very comment. - - - - - 9a9c2f03 by Cheng Shao at 2025-12-18T13:24:39-05:00 compiler: remove unused OtherSection logic This patch removes the OtherSection logic in Cmm, given it's never actually used by any of our backends. - - - - - 91edd292 by Wolfgang Jeltsch at 2025-12-19T03:18:19-05:00 Remove unused known-key and name variables for generics This removes the known-key and corresponding name variables for `K1`, `M1`, `R`, `D`, `C`, `S`, and `URec` from `GHC.Generics`, as they are apparently nowhere used in GHC’s source code. - - - - - 73ee7e38 by Wolfgang Jeltsch at 2025-12-19T03:19:02-05:00 Remove unused known keys and names for generics classes This removes the known-key and corresponding name variables for `Datatype`, `Constructor`, and `Selector` from `GHC.Generics`, as they are apparently nowhere used in GHC’s source code. - - - - - f69c5f14 by Cheng Shao at 2025-12-19T03:19:45-05:00 wasm: fix handling of ByteArray#/MutableByteArray# arguments in JSFFI imports This patch fixes the handling of ByteArray#/MutableByteArray# arguments in JSFFI imports, see the amended note and manual for explanation. Also adds a test to witness the fix. Co-authored-by: Codex <codex(a)openai.com> - - - - - 224446a2 by Cheng Shao at 2025-12-20T07:49:54-05:00 rts: workaround -Werror=maybe-uninitialized false positives In some cases gcc might report -Werror=maybe-uninitialized that we know are false positives, but need to workaround it to make validate builds with -Werror pass. - - - - - 251ec087 by Cheng Shao at 2025-12-20T07:49:54-05:00 hadrian: use -Og as C/C++ optimization level when debugging This commit enables -Og as optimization level when compiling the debug ways of rts. According to gcc documentation (https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-Og) -Og is a better choice than -O0 for producing debuggable code. It's also supported by clang as well, so it makes sense to use it as a default for debugging. Also add missing -g3 flag to C++ compilation flags in +debug_info flavour transformer. - - - - - fb586c67 by Cheng Shao at 2025-12-20T07:50:36-05:00 compiler: replace DList with OrdList This patch removes `DList` logic from the compiler and replaces it with `OrdList` which also supports O(1) concatenation and should be more memory efficient than the church-encoded `DList`. - - - - - 8149c987 by Cheng Shao at 2025-12-20T17:06:51-05:00 hadrian: add with_profiled_libs flavour transformer This patch adds a `with_profiled_libs` flavour transformer to hadrian which is the exact opposite of `no_profiled_libs`. It adds profiling ways to stage1+ rts/library ways, and doesn't alter other flavour settings. It is useful when needing to test profiling logic locally with a quick flavour. - - - - - 746b18cd by Cheng Shao at 2025-12-20T17:06:51-05:00 hadrian: fix missing profiled dynamic libraries in profiled_ghc This commit fixes the profiled_ghc flavour transformer to include profiled dynamic libraries as well, since they're supported by GHC since !12595. - - - - - 4dd7e3b9 by Cheng Shao at 2025-12-20T17:07:33-05:00 ci: set http.postBuffer to mitigate perf notes timeout on some runners This patch sets http.postBuffer to mitigate the timeout when fetching perf notes on some runners with slow internet connection. Fixes #26684. - - - - - bc36268a by Wolfgang Jeltsch at 2025-12-21T16:23:24-05:00 Remove unused known keys and names for type representations This removes the known-key and corresponding name variables for `TrName`, `TrNameD`, `TypeRep`, `KindRepTypeLitD`, `TypeLitSort`, and `mkTrType`, as they are apparently nowhere used in GHC’s source code. - - - - - ff5050e9 by Wolfgang Jeltsch at 2025-12-21T16:24:04-05:00 Remove unused known keys and names for natural operations This removes the known-key and corresponding name variables for `naturalAndNot`, `naturalLog2`, `naturalLogBaseWord`, `naturalLogBase`, `naturalPowMod`, `naturalSizeInBase`, `naturalToFloat`, and `naturalToDouble`, as they are apparently nowhere used in GHC’s source code. - - - - - 424388c2 by Wolfgang Jeltsch at 2025-12-21T16:24:45-05:00 Remove the unused known key and name for `Fingerprint` This removes the variables for the known key and the name of the `Fingerprint` data constructor, as they are apparently nowhere used in GHC’s source code. - - - - - a1ed86fe by Wolfgang Jeltsch at 2025-12-21T16:25:26-05:00 Remove the unused known key and name for `failIO` This removes the variables for the known key and the name of the `failIO` operation, as they are apparently nowhere used in GHC’s source code. - - - - - b8220daf by Wolfgang Jeltsch at 2025-12-21T16:26:07-05:00 Remove the unused known key and name for `liftM` This removes the variables for the known key and the name of the `liftM` operation, as they are apparently nowhere used in GHC’s source code. - - - - - eb0628b1 by Wolfgang Jeltsch at 2025-12-21T16:26:47-05:00 Fix the documentation of `hIsClosed` - - - - - db1ce858 by sheaf at 2025-12-22T17:11:17-05:00 Do deep subsumption when computing valid hole fits This commit makes a couple of improvements to the code that computes "valid hole fits": 1. It uses deep subsumption for data constructors. This matches up the multiplicities, as per Note [Typechecking data constructors]. This fixes #26338 (test: LinearHoleFits). 2. It now suggests (non-unidirectional) pattern synonyms as valid hole fits. This fixes #26339 (test: PatSynHoleFit). 3. It uses 'stableNameCmp', to make the hole fit output deterministic. ------------------------- Metric Increase: hard_hole_fits ------------------------- - - - - - 72ee9100 by sheaf at 2025-12-22T17:11:17-05:00 Speed up hole fits with a quick pre-test This speeds up the machinery for valid hole fits by doing a small check to rule out obviously wrong hole fits, such as: 1. A hole fit identifier whose type has a different TyCon at the head, after looking through foralls and (=>) arrows, e.g.: hole_ty = Int cand_ty = Maybe a or hole_ty = forall a b. a -> b cand_ty = forall x y. Either x y 2. A hole fit identifier that is not polymorphic when the hole type is polymorphic, e.g. hole_ty = forall a. a -> a cand_ty = Int -> Int ------------------------- Metric Decrease: hard_hole_fits ------------------------- - - - - - 30e513ba by Cheng Shao at 2025-12-22T17:12:00-05:00 configure: remove unused win32-tarballs.md5sum This patch removes the unused `win32-tarballs.md5sum` file from the tree. The current mingw tarball download logic in `mk/get-win32-tarballs.py` fetches and checks against `SHA256SUM` from the same location where the tarballs are fetched, and this file has been unused for a few years. - - - - - a2d52b3b by Wolfgang Jeltsch at 2025-12-23T04:47:33-05:00 Add an operation `System.IO.hGetNewlineMode` This commit also contains some small code and documentation changes for related operations, for the sake of consistency. - - - - - b26d134a by Cheng Shao at 2025-12-23T04:48:15-05:00 rts: opportunistically reclaim slop space in shrinkMutableByteArray# Previously, `shrinkMutableByteArray#` shrinks a `MutableByteArray#` in-place by assigning the new size to it, and zeroing the extra slop space. That slop space is not reclaimed and wasted. But it's often the case that we allocate a `MutableByteArray#` upfront, then shrink it shortly after, so the `MutableByteArray#` closure sits right at the end of a nursery block; this patch identifies such chances, and also shrink `bd->free` if possible, reducing heap space fragmentation. Co-authored-by: Codex <codex(a)openai.com> ------------------------- Metric Decrease: T10678 ------------------------- - - - - - c72ddabf by Cheng Shao at 2025-12-23T16:13:23-05:00 hadrian: fix bootstrapping with ghc-9.14 This patch fixes bootstrapping GHC with ghc-9.14, tested locally with ghc-9.14.1 release as bootstrapping GHC. - - - - - 0fd6d8e4 by Cheng Shao at 2025-12-23T16:14:05-05:00 hadrian: pass -keep-tmp-files to test ghc when --keep-test-files is enabled This patch makes hadrian pass `-keep-tmp-files` to test ghc when `--keep-test-files` is enabled, so you can check the ghc intermediate files when debugging certain test failures. Closes #26688. - - - - - 81d10134 by Cheng Shao at 2025-12-24T06:11:52-05:00 configure: remove dead code in configure scripts This patch removes dead code in our configure scripts, including: - Variables and auto-detected programs that are not used - autoconf functions that are not used, or export a variable that's not used - `AC_CHECK_HEADERS` invocations that don't have actual corresponding `HAVE_XXX_H` usage - Other dead code (e.g. stray `AC_DEFUN()`) Co-authored-by: Codex <codex(a)openai.com> - - - - - fb1381c3 by Wolfgang Jeltsch at 2025-12-24T06:12:34-05:00 Remove unused known keys and names for list operations This removes the known-key and corresponding name variables for `concat`, `filter`, `zip`, and `(++)`, as they are apparently nowhere used in GHC’s source code. - - - - - 7b9c20f4 by Recursion Ninja at 2025-12-24T10:35:36-05:00 Decoupling Language.Haskell.Syntax.Binds from GHC.Types.Basic by transferring InlinePragma types between the modules. * Moved InlinePragma data-types to Language.Haskell.Syntax.Binds.InlinePragma * Partitioned of Arity type synonyms to GHC.Types.Arity * InlinePragma is now extensible via Trees That Grow * Activation is now extensible via Trees That Grow * Maybe Arity change to more descriptive InlineSaturation data-type * InlineSaturation information removed from InlinePragma during GHS parsing pass * Cleaned up the exposed module interfaces of the new modules - - - - - a3afae0c by Simon Peyton Jones at 2025-12-25T15:26:36-05:00 Check for rubbish literals in Lint Addresses #26607. See new Note [Checking for rubbish literals] in GHC.Core.Lint - - - - - d4f9bca2 by Simon Peyton Jones at 2025-12-31T09:42:07+00:00 Experiment with switching off optCoercion entirely - - - - - 90438e6f by Simon Peyton Jones at 2025-12-31T09:42:07+00:00 Do isReflexiveCo in the Simplifier - - - - - 05873d95 by Simon Peyton Jones at 2025-12-31T09:42:07+00:00 Make coercion optimisation into its own pass In this MR: * -fopt-coercion / -fno-opt-coercion switches the pass on and off * -fopt-coercion is on by default * The pass runs just once, right at the start of the pipeline - - - - - 34995b98 by Simon Peyton Jones at 2025-12-31T09:42:07+00:00 Update user manual - - - - - 638 changed files: - .gitattributes - .gitlab-ci.yml - .gitlab/ci.sh - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - .gitlab/rel_eng/fetch-gitlab-artifacts/fetch_gitlab.py - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - .gitlab/test-metrics.sh - compiler/GHC.hs - compiler/GHC/Builtin/Names.hs - compiler/GHC/Builtin/PrimOps.hs - 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libraries/base/src/System/IO.hs - libraries/exceptions - libraries/ghc-internal/configure.ac - libraries/ghc-internal/src/GHC/Internal/Control/Monad/ST/Lazy/Imp.hs - libraries/ghc-internal/src/GHC/Internal/Data/OldList.hs - libraries/ghc-internal/src/GHC/Internal/Functor/ZipList.hs - libraries/ghc-internal/src/GHC/Internal/IO/Handle.hs - libraries/ghc-internal/src/GHC/Internal/System/IO.hs - − m4/find_ghc_bootstrap_prog.m4 - − m4/fp_copy_shellvar.m4 - − m4/fp_prog_ld_flag.m4 - − m4/fp_prog_sort.m4 - m4/prep_target_file.m4 - − mk/win32-tarballs.md5sum - + rts/.ubsan-suppressions - rts/Apply.cmm - rts/Compact.cmm - rts/ContinuationOps.cmm - rts/Exception.cmm - rts/Interpreter.c - rts/Jumps.h - rts/PrimOps.cmm - rts/RtsMessages.c - rts/StgMiscClosures.cmm - rts/StgStartup.cmm - rts/configure.ac - rts/include/Stg.h - rts/include/rts/Messages.h - rts/include/stg/Types.h - rts/linker/InitFini.c - rts/prim/mulIntMayOflo.c - rts/rts.cabal - rts/sm/Sanity.c - testsuite/driver/testglobals.py - testsuite/driver/testlib.py - 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+ testsuite/tests/patsyn/should_fail/import-syntax-no-ext.stderr - testsuite/tests/perf/compiler/hard_hole_fits.stderr - testsuite/tests/perf/should_run/all.T - testsuite/tests/plugins/test-hole-plugin.stderr - + testsuite/tests/rename/should_compile/T25901_sub_e.hs - + testsuite/tests/rename/should_compile/T25901_sub_f.hs - + testsuite/tests/rename/should_compile/T25901_sub_f.stderr - + testsuite/tests/rename/should_compile/T25901_sub_g.hs - + testsuite/tests/rename/should_compile/T25901_sub_g.stderr - + testsuite/tests/rename/should_compile/T25901_sub_g_helper.hs - testsuite/tests/rename/should_compile/all.T - testsuite/tests/rename/should_fail/T23570b.stderr - + testsuite/tests/rename/should_fail/T25901_sub_a.hs - + testsuite/tests/rename/should_fail/T25901_sub_a.stderr - + testsuite/tests/rename/should_fail/T25901_sub_b.hs - + testsuite/tests/rename/should_fail/T25901_sub_b.stderr - + testsuite/tests/rename/should_fail/T25901_sub_c.hs - + testsuite/tests/rename/should_fail/T25901_sub_c.stderr - 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+ testsuite/tests/warnings/should_compile/DodgyImports03.hs - + testsuite/tests/warnings/should_compile/DodgyImports03.stderr - + testsuite/tests/warnings/should_compile/DodgyImports03_helper.hs - + testsuite/tests/warnings/should_compile/DodgyImports04.hs - + testsuite/tests/warnings/should_compile/DodgyImports04.stderr - testsuite/tests/warnings/should_compile/DodgyImports_hiding.stderr - testsuite/tests/warnings/should_compile/all.T - utils/check-exact/ExactPrint.hs - utils/deriveConstants/Main.hs - utils/genapply/Main.hs - utils/haddock/haddock-api/haddock-api.cabal - − utils/haddock/haddock-api/src/Haddock/Backends/HaddockDB.hs - utils/haddock/haddock-api/src/Haddock/Interface/Create.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f94fb33cdcc192e81b01424017008f… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f94fb33cdcc192e81b01424017008f… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/T26709] Improve case merging
by Simon Peyton Jones (＠simonpj) 31 Dec '25

31 Dec '25

Simon Peyton Jones pushed to branch wip/T26709 at Glasgow Haskell Compiler / GHC Commits: 1cb9b4d9 by Simon Peyton Jones at 2025-12-31T09:41:09+00:00 Improve case merging This small MR makes case merging happen a bit more often than it otherwise could, by getting join points out of the way. See #26709 and GHC.Core.Utils Note [Floating join points out of DEFAULT alternatives] - - - - - 5 changed files: - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Core/Utils.hs - + testsuite/tests/simplCore/should_compile/T26709.hs - + testsuite/tests/simplCore/should_compile/T26709.stderr - testsuite/tests/simplCore/should_compile/all.T Changes: ===================================== compiler/GHC/Core/Opt/Simplify/Utils.hs ===================================== @@ -2693,7 +2693,7 @@ mkCase, mkCase1, mkCase2, mkCase3 mkCase mode scrut outer_bndr alts_ty alts | sm_case_merge mode - , Just (joins, alts') <- mergeCaseAlts outer_bndr alts + , Just (joins, alts') <- mergeCaseAlts scrut outer_bndr alts = do { tick (CaseMerge outer_bndr) ; case_expr <- mkCase1 mode scrut outer_bndr alts_ty alts' ; return (mkLets joins case_expr) } ===================================== compiler/GHC/Core/Utils.hs ===================================== @@ -73,7 +73,7 @@ import GHC.Platform import GHC.Core import GHC.Core.Ppr -import GHC.Core.FVs( bindFreeVars ) +import GHC.Core.FVs( exprFreeVars, bindFreeVars ) import GHC.Core.DataCon import GHC.Core.Type as Type import GHC.Core.Predicate( isEqPred ) @@ -113,11 +113,11 @@ import GHC.Utils.Outputable import GHC.Utils.Panic import GHC.Utils.Misc +import Control.Monad ( guard ) import Data.ByteString ( ByteString ) import Data.Function ( on ) import Data.List ( sort, sortBy, partition, zipWith4, mapAccumL ) import Data.Ord ( comparing ) -import Control.Monad ( guard ) import qualified Data.Set as Set {- @@ -674,11 +674,12 @@ filters down the matching alternatives in GHC.Core.Opt.Simplify.rebuildCase. -} --------------------------------- -mergeCaseAlts :: Id -> [CoreAlt] -> Maybe ([CoreBind], [CoreAlt]) +mergeCaseAlts :: CoreExpr -> Id -> [CoreAlt] -> Maybe ([CoreBind], [CoreAlt]) -- See Note [Merge Nested Cases] -mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) +mergeCaseAlts scrut outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) | Just (joins, inner_alts) <- go deflt_rhs - = Just (joins, mergeAlts outer_alts inner_alts) + , Just aux_binds <- mk_aux_binds joins + = Just ( aux_binds ++ joins, mergeAlts outer_alts inner_alts ) -- NB: mergeAlts gives priority to the left -- case x of -- A -> e1 @@ -688,6 +689,20 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) -- When we merge, we must ensure that e1 takes -- precedence over e2 as the value for A! where + scrut_fvs = exprFreeVars scrut + + -- See Note [Floating join points out of DEFAULT alternatives] + mk_aux_binds join_binds + | not (any mentions_outer_bndr join_binds) + = Just [] -- Good! No auxiliary bindings needed + | exprIsTrivial scrut + , not (outer_bndr `elemVarSet` scrut_fvs) + = Just [NonRec outer_bndr scrut] -- Need a fixup binding + | otherwise + = Nothing -- Can't do it + + mentions_outer_bndr bind = outer_bndr `elemVarSet` bindFreeVars bind + go :: CoreExpr -> Maybe ([CoreBind], [CoreAlt]) -- Whizzo: we can merge! @@ -725,11 +740,10 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) = do { (joins, alts) <- go body -- Check for capture; but only if we could otherwise do a merge - ; let capture = outer_bndr `elem` bindersOf bind - || outer_bndr `elemVarSet` bindFreeVars bind - ; guard (not capture) + -- (i.e. the recursive `go` succeeds) + ; guard (okToFloatJoin scrut_fvs outer_bndr bind) - ; return (bind:joins, alts ) } + ; return (bind : joins, alts ) } | otherwise = Nothing @@ -741,7 +755,18 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) go _ = Nothing -mergeCaseAlts _ _ = Nothing +mergeCaseAlts _ _ _ = Nothing + +okToFloatJoin :: VarSet -> Id -> CoreBind -> Bool +-- Check a join-point binding to see if it can be floated out of +-- the DEFAULT branch of a `case`. +-- See Note [Floating join points out of DEFAULT alternatives] +okToFloatJoin scrut_fvs outer_bndr bind + = not (any bad_bndr (bindersOf bind)) + where + bad_bndr bndr = bndr == outer_bndr -- (a) + || bndr `elemVarSet` scrut_fvs -- (b) + --------------------------------- mergeAlts :: [Alt a] -> [Alt a] -> [Alt a] @@ -950,10 +975,46 @@ Wrinkles non-join-points unless the /outer/ case has just one alternative; doing so would risk more allocation + Floating out join points isn't entirely straightforward. + See Note [Floating join points out of DEFAULT alternatives] + (MC5) See Note [Cascading case merge] See also Note [Example of case-merging and caseRules] in GHC.Core.Opt.Simplify.Utils +Note [Floating join points out of DEFAULT alternatives] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Consider this, from (MC4) of Note [Merge Nested Cases] + case x of r + DEFAULT -> join j = rhs in case r of ... + alts + +We want to float that join point out to give this + join j = rhs + case x of r + DEFAULT -> case r of ... + alts + +But doing so is flat-out wrong if the scoping gets messed up: + (a) case x of r { DEFAULT -> join r = ... in ...r... } + (b) case j of r { DEFAULT -> join j = ... in ... } + (c) case x of r { DEFAULT -> join j = ...r.. in ... } +In all these cases we can't float the join point out because r changes its +meaning. For (a) and (b) the Simplifier removes shadowing, so they'll +be solved in the next iteration. But case (c) will persist. + +Happily, we can fix up case (c) by adding an auxiliary binding, like this + let r = e in + join j = rhs[r] + case e of r + DEFAULT -> ...r... + ...other alts... + +We can only do this if + * We don't introduce shadowing: that is `j` and `r` do not appear free in `e`. + (Again the Simplifier will eliminate such shadowing.) + * The scrutinee `e` is trivial so that the transformation doesn't duplicate work. + Note [Cascading case merge] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ===================================== testsuite/tests/simplCore/should_compile/T26709.hs ===================================== @@ -0,0 +1,11 @@ +module T26709 where + +data T = A | B | C + +f x = case x of + A -> True + _ -> let {-# NOINLINE j #-} + j y = y && not (f x) + in case x of + B -> j True + C -> j False ===================================== testsuite/tests/simplCore/should_compile/T26709.stderr ===================================== @@ -0,0 +1,32 @@ +[1 of 1] Compiling T26709 ( T26709.hs, T26709.o ) + +==================== Tidy Core ==================== +Result size of Tidy Core + = {terms: 26, types: 9, coercions: 0, joins: 1/1} + +Rec { +-- RHS size: {terms: 25, types: 7, coercions: 0, joins: 1/1} +f [Occ=LoopBreaker] :: T -> Bool +[GblId, Arity=1, Str=<SL>, Unf=OtherCon []] +f = \ (x :: T) -> + join { + j [InlPrag=NOINLINE, Dmd=MC(1,L)] :: Bool -> Bool + [LclId[JoinId(1)(Just [!])], Arity=1, Str=<1L>, Unf=OtherCon []] + j (eta [OS=OneShot] :: Bool) + = case eta of { + False -> GHC.Internal.Types.False; + True -> + case f x of { + False -> GHC.Internal.Types.True; + True -> GHC.Internal.Types.False + } + } } in + case x of { + A -> GHC.Internal.Types.True; + B -> jump j GHC.Internal.Types.True; + C -> jump j GHC.Internal.Types.False + } +end Rec } + + + ===================================== testsuite/tests/simplCore/should_compile/all.T ===================================== @@ -563,3 +563,8 @@ test('T26115', [grep_errmsg(r'DFun')], compile, ['-O -ddump-simpl -dsuppress-uni test('T26116', normal, compile, ['-O -ddump-rules']) test('T26117', [grep_errmsg(r'==')], compile, ['-O -ddump-simpl -dsuppress-uniques']) test('T26349', normal, compile, ['-O -ddump-rules']) + +# T26709: we expect three `case` expressions not four +test('T26709', [grep_errmsg(r'case')], + multimod_compile, + ['T26709', '-O -ddump-simpl -dsuppress-uniques -dno-typeable-binds']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/1cb9b4d9713a833a4477649dfbd7469… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/1cb9b4d9713a833a4477649dfbd7469… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/T26709] 2 commits: Refactor srutOkForBinderSwap
by Simon Peyton Jones (＠simonpj) 31 Dec '25

31 Dec '25

Simon Peyton Jones pushed to branch wip/T26709 at Glasgow Haskell Compiler / GHC Commits: c3555d08 by Simon Peyton Jones at 2025-12-31T09:25:09+00:00 Refactor srutOkForBinderSwap This MR does a small refactor: * Moves `scrutOkForBinderSwap` and `BinderSwapDecision` to GHC.Core.Utils * Inverts the sense of the coercion it returns, which makes more sense No effect on behaviour - - - - - b5544586 by Simon Peyton Jones at 2025-12-31T09:27:03+00:00 Improve case merging This small MR makes case merging happen a bit more often than it otherwise could, by getting join points out of the way. See #26709 and GHC.Core.Utils Note [Floating join points out of DEFAULT alternatives] - - - - - 7 changed files: - compiler/GHC/Core/Opt/OccurAnal.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Core/Utils.hs - + testsuite/tests/simplCore/should_compile/T26709.hs - + testsuite/tests/simplCore/should_compile/T26709.stderr - testsuite/tests/simplCore/should_compile/all.T Changes: ===================================== compiler/GHC/Core/Opt/OccurAnal.hs ===================================== @@ -28,7 +28,7 @@ core expression with (hopefully) improved usage information. module GHC.Core.Opt.OccurAnal ( occurAnalysePgm, occurAnalyseExpr, - zapLambdaBndrs, BinderSwapDecision(..), scrutOkForBinderSwap + zapLambdaBndrs ) where import GHC.Prelude hiding ( head, init, last, tail ) @@ -36,7 +36,7 @@ import GHC.Prelude hiding ( head, init, last, tail ) import GHC.Core import GHC.Core.FVs import GHC.Core.Utils ( exprIsTrivial, isDefaultAlt, isExpandableApp, - mkCastMCo, mkTicks ) + mkCastMCo, mkTicks, BinderSwapDecision(..), scrutOkForBinderSwap ) import GHC.Core.Opt.Arity ( joinRhsArity, isOneShotBndr ) import GHC.Core.Coercion import GHC.Core.Type @@ -3537,6 +3537,7 @@ doesn't use it. So this is only to satisfy the perhaps-over-picky Lint. -} addBndrSwap :: OutExpr -> Id -> OccEnv -> OccEnv +-- See Note [Binder swap] -- See Note [The binder-swap substitution] addBndrSwap scrut case_bndr env@(OccEnv { occ_bs_env = swap_env, occ_bs_rng = rng_vars }) @@ -3544,7 +3545,7 @@ addBndrSwap scrut case_bndr , scrut_var /= case_bndr -- Consider: case x of x { ... } -- Do not add [x :-> x] to occ_bs_env, else lookupBndrSwap will loop - = env { occ_bs_env = extendVarEnv swap_env scrut_var (case_bndr', mco) + = env { occ_bs_env = extendVarEnv swap_env scrut_var (case_bndr', mkSymMCo mco) , occ_bs_rng = rng_vars `extendVarSet` case_bndr' `unionVarSet` tyCoVarsOfMCo mco } @@ -3554,27 +3555,6 @@ addBndrSwap scrut case_bndr case_bndr' = zapIdOccInfo case_bndr -- See Note [Zap case binders in proxy bindings] --- | See bBinderSwaOk. -data BinderSwapDecision - = NoBinderSwap - | DoBinderSwap OutVar MCoercion - -scrutOkForBinderSwap :: OutExpr -> BinderSwapDecision --- If (scrutOkForBinderSwap e = DoBinderSwap v mco, then --- v = e |> mco --- See Note [Case of cast] --- See Historical Note [Care with binder-swap on dictionaries] --- --- We use this same function in SpecConstr, and Simplify.Iteration, --- when something binder-swap-like is happening -scrutOkForBinderSwap e - = case e of - Tick _ e -> scrutOkForBinderSwap e -- Drop ticks - Var v -> DoBinderSwap v MRefl - Cast (Var v) co -> DoBinderSwap v (MCo (mkSymCo co)) - -- Cast: see Note [Case of cast] - _ -> NoBinderSwap - lookupBndrSwap :: OccEnv -> Id -> (CoreExpr, Id) -- See Note [The binder-swap substitution] -- Returns an expression of the same type as Id ===================================== compiler/GHC/Core/Opt/Simplify/Iteration.hs ===================================== @@ -22,7 +22,7 @@ import GHC.Core.TyCo.Compare( eqType ) import GHC.Core.Opt.Simplify.Env import GHC.Core.Opt.Simplify.Inline import GHC.Core.Opt.Simplify.Utils -import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr, zapLambdaBndrs, scrutOkForBinderSwap, BinderSwapDecision (..) ) +import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr, zapLambdaBndrs ) import GHC.Core.Make ( FloatBind, mkImpossibleExpr, castBottomExpr ) import qualified GHC.Core.Make import GHC.Core.Coercion hiding ( substCo, substCoVar ) @@ -3601,11 +3601,13 @@ addAltUnfoldings env case_bndr bndr_swap con_app env1 = addBinderUnfolding env case_bndr con_app_unf -- See Note [Add unfolding for scrutinee] + -- e.g. case (x |> co) of K a b -> blah + -- We add to `x` the unfolding (K a b |> sym co) env2 | DoBinderSwap v mco <- bndr_swap = addBinderUnfolding env1 v $ if isReflMCo mco -- isReflMCo: avoid calling mk_simple_unf then con_app_unf -- twice in the common case - else mk_simple_unf (mkCastMCo con_app mco) + else mk_simple_unf (mkCastMCo con_app (mkSymMCo mco)) | otherwise = env1 ===================================== compiler/GHC/Core/Opt/Simplify/Utils.hs ===================================== @@ -2693,7 +2693,7 @@ mkCase, mkCase1, mkCase2, mkCase3 mkCase mode scrut outer_bndr alts_ty alts | sm_case_merge mode - , Just (joins, alts') <- mergeCaseAlts outer_bndr alts + , Just (joins, alts') <- mergeCaseAlts scrut outer_bndr alts = do { tick (CaseMerge outer_bndr) ; case_expr <- mkCase1 mode scrut outer_bndr alts_ty alts' ; return (mkLets joins case_expr) } ===================================== compiler/GHC/Core/Utils.hs ===================================== @@ -19,6 +19,7 @@ module GHC.Core.Utils ( mergeAlts, mergeCaseAlts, trimConArgs, filterAlts, combineIdenticalAlts, refineDefaultAlt, scaleAltsBy, + BinderSwapDecision(..), scrutOkForBinderSwap, -- * Properties of expressions exprType, coreAltType, coreAltsType, @@ -72,7 +73,7 @@ import GHC.Platform import GHC.Core import GHC.Core.Ppr -import GHC.Core.FVs( bindFreeVars ) +import GHC.Core.FVs( exprFreeVars, bindFreeVars ) import GHC.Core.DataCon import GHC.Core.Type as Type import GHC.Core.Predicate( isEqPred ) @@ -112,11 +113,11 @@ import GHC.Utils.Outputable import GHC.Utils.Panic import GHC.Utils.Misc +import Control.Monad ( guard ) import Data.ByteString ( ByteString ) import Data.Function ( on ) import Data.List ( sort, sortBy, partition, zipWith4, mapAccumL ) import Data.Ord ( comparing ) -import Control.Monad ( guard ) import qualified Data.Set as Set {- @@ -590,6 +591,28 @@ The default alternative must be first, if it exists at all. This makes it easy to find, though it makes matching marginally harder. -} +data BinderSwapDecision + = NoBinderSwap + | DoBinderSwap OutVar MCoercion + +scrutOkForBinderSwap :: OutExpr -> BinderSwapDecision +-- If (scrutOkForBinderSwap e = DoBinderSwap v mco, then +-- e = v |> mco +-- See Note [Case of cast] +-- See Historical Note [Care with binder-swap on dictionaries] +-- +-- We use this same function in SpecConstr, and Simplify.Iteration, +-- when something binder-swap-like is happening +-- +-- See Note [Binder swap] in GHC.Core.Opt.OccurAnal +scrutOkForBinderSwap e + = case e of + Tick _ e -> scrutOkForBinderSwap e -- Drop ticks + Var v -> DoBinderSwap v MRefl + Cast (Var v) co -> DoBinderSwap v (MCo co) + -- Cast: see Note [Case of cast] + _ -> NoBinderSwap + -- | Extract the default case alternative findDefault :: [Alt b] -> ([Alt b], Maybe (Expr b)) findDefault (Alt DEFAULT args rhs : alts) = assert (null args) (alts, Just rhs) @@ -651,11 +674,12 @@ filters down the matching alternatives in GHC.Core.Opt.Simplify.rebuildCase. -} --------------------------------- -mergeCaseAlts :: Id -> [CoreAlt] -> Maybe ([CoreBind], [CoreAlt]) +mergeCaseAlts :: CoreExpr -> Id -> [CoreAlt] -> Maybe ([CoreBind], [CoreAlt]) -- See Note [Merge Nested Cases] -mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) +mergeCaseAlts scrut outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) | Just (joins, inner_alts) <- go deflt_rhs - = Just (joins, mergeAlts outer_alts inner_alts) + , Just aux_binds <- mk_aux_binds joins + = Just ( aux_binds ++ joins, mergeAlts outer_alts inner_alts ) -- NB: mergeAlts gives priority to the left -- case x of -- A -> e1 @@ -665,6 +689,20 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) -- When we merge, we must ensure that e1 takes -- precedence over e2 as the value for A! where + scrut_fvs = exprFreeVars scrut + + -- See Note [Floating join points out of DEFAULT alternatives] + mk_aux_binds join_binds + | not (any mentions_outer_bndr join_binds) + = Just [] -- Good! No auxiliary bindings needed + | exprIsTrivial scrut + , not (outer_bndr `elemVarSet` scrut_fvs) + = Just [NonRec outer_bndr scrut] -- Need a fixup binding + | otherwise + = Nothing -- Can't do it + + mentions_outer_bndr bind = outer_bndr `elemVarSet` bindFreeVars bind + go :: CoreExpr -> Maybe ([CoreBind], [CoreAlt]) -- Whizzo: we can merge! @@ -702,11 +740,10 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) = do { (joins, alts) <- go body -- Check for capture; but only if we could otherwise do a merge - ; let capture = outer_bndr `elem` bindersOf bind - || outer_bndr `elemVarSet` bindFreeVars bind - ; guard (not capture) + -- (i.e. the recursive `go` succeeds) + ; guard (okToFloatJoin scrut_fvs outer_bndr bind) - ; return (bind:joins, alts ) } + ; return (bind : joins, alts ) } | otherwise = Nothing @@ -718,7 +755,19 @@ mergeCaseAlts outer_bndr (Alt DEFAULT _ deflt_rhs : outer_alts) go _ = Nothing -mergeCaseAlts _ _ = Nothing +mergeCaseAlts _ _ _ = Nothing + +okToFloatJoin :: VarSet -> Id -> CoreBind -> Bool +-- Check a join-point binding to see if it can be floated out of +-- the DEFAULT branch of a `case`. A Just result means "yes", +-- and the [CoreBInd] are the extra fix-up bindings to add. +-- See Note [Floating join points out of DEFAULT alternatives] +okToFloatJoin scrut_fvs outer_bndr bind + = not (any bad_bndr (bindersOf bind)) + where + bad_bndr bndr = bndr == outer_bndr -- (a) + || bndr `elemVarSet` scrut_fvs -- (b) + --------------------------------- mergeAlts :: [Alt a] -> [Alt a] -> [Alt a] @@ -927,10 +976,46 @@ Wrinkles non-join-points unless the /outer/ case has just one alternative; doing so would risk more allocation + Floating out join points isn't entirely straightforward. + See Note [Floating join points out of DEFAULT alternatives] + (MC5) See Note [Cascading case merge] See also Note [Example of case-merging and caseRules] in GHC.Core.Opt.Simplify.Utils +Note [Floating join points out of DEFAULT alternatives] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Consider this, from (MC4) of Note [Merge Nested Cases] + case x of r + DEFAULT -> join j = rhs in case r of ... + alts + +We want to float that join point out to give this + join j = rhs + case x of r + DEFAULT -> case r of ... + alts + +But doing so is flat-out wrong if the scoping gets messed up: + (a) case x of r { DEFAULT -> join r = ... in ...r... } + (b) case j of r { DEFAULT -> join j = ... in ... } + (c) case x of r { DEFAULT -> join j = ...r.. in ... } +In all these cases we can't float the join point out because r changes its +meaning. For (a) and (b) the Simplifier removes shadowing, so they'll +be solved in the next iteration. But case (c) will persist. + +Happily, we can fix up case (c) by adding an auxiliary binding, like this + let r = e in + join j = rhs[r] + case e of r + DEFAULT -> ...r... + ...other alts... + +We can only do this if + * We don't introduce shadowing: that is `j` and `r` do not appear free in `e`. + (Again the Simplifier will eliminate such shadowing.) + * The scrutinee `e` is trivial so that the transformation doesn't duplicate work. + Note [Cascading case merge] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ===================================== testsuite/tests/simplCore/should_compile/T26709.hs ===================================== @@ -0,0 +1,11 @@ +module T26709 where + +data T = A | B | C + +f x = case x of + A -> True + _ -> let {-# NOINLINE j #-} + j y = y && not (f x) + in case x of + B -> j True + C -> j False ===================================== testsuite/tests/simplCore/should_compile/T26709.stderr ===================================== @@ -0,0 +1,32 @@ +[1 of 1] Compiling T26709 ( T26709.hs, T26709.o ) + +==================== Tidy Core ==================== +Result size of Tidy Core + = {terms: 26, types: 9, coercions: 0, joins: 1/1} + +Rec { +-- RHS size: {terms: 25, types: 7, coercions: 0, joins: 1/1} +f [Occ=LoopBreaker] :: T -> Bool +[GblId, Arity=1, Str=<SL>, Unf=OtherCon []] +f = \ (x :: T) -> + join { + j [InlPrag=NOINLINE, Dmd=MC(1,L)] :: Bool -> Bool + [LclId[JoinId(1)(Just [!])], Arity=1, Str=<1L>, Unf=OtherCon []] + j (eta [OS=OneShot] :: Bool) + = case eta of { + False -> GHC.Internal.Types.False; + True -> + case f x of { + False -> GHC.Internal.Types.True; + True -> GHC.Internal.Types.False + } + } } in + case x of { + A -> GHC.Internal.Types.True; + B -> jump j GHC.Internal.Types.True; + C -> jump j GHC.Internal.Types.False + } +end Rec } + + + ===================================== testsuite/tests/simplCore/should_compile/all.T ===================================== @@ -563,3 +563,8 @@ test('T26115', [grep_errmsg(r'DFun')], compile, ['-O -ddump-simpl -dsuppress-uni test('T26116', normal, compile, ['-O -ddump-rules']) test('T26117', [grep_errmsg(r'==')], compile, ['-O -ddump-simpl -dsuppress-uniques']) test('T26349', normal, compile, ['-O -ddump-rules']) + +# T26709: we expect three `case` expressions not four +test('T26709', [grep_errmsg(r'case')], + multimod_compile, + ['T26709', '-O -ddump-simpl -dsuppress-uniques -dno-typeable-binds']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/4b2f2236af8214ccdefdd643d1f2fa… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/4b2f2236af8214ccdefdd643d1f2fa… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc] Pushed new branch wip/sm-no-sweep
by Cheng Shao (＠TerrorJack) 30 Dec '25

30 Dec '25

Cheng Shao pushed new branch wip/sm-no-sweep at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/sm-no-sweep You're receiving this email because of your account on gitlab.haskell.org.

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