[Git][ghc/ghc][wip/T25944] 32 commits: Specialise: Improve specialisation by refactoring interestingDict

Sebastian Graf pushed to branch wip/T25944 at Glasgow Haskell Compiler / GHC Commits: f707bab4 by Andreas Klebinger at 2025-07-12T14:56:16+01:00 Specialise: Improve specialisation by refactoring interestingDict This MR addresses #26051, which concerns missed type-class specialisation. The main payload of the MR is to completely refactor the key function `interestingDict` in GHC.Core.Opt.Specialise The main change is that we now also look at the structure of the dictionary we consider specializing on, rather than only the type. See the big `Note [Interesting dictionary arguments]` - - - - - ca7a9d42 by Simon Peyton Jones at 2025-07-12T14:56:16+01:00 Treat tuple dictionaries uniformly; don't unbox them See `Note [Do not unbox class dictionaries]` in DmdAnal.hs, sep (DNB1). This MR reverses the plan in #23398, which suggested a special case to unbox tuple dictionaries in worker/wrapper. But: - This was the cause of a pile of complexity in the specialiser (#26158) - Even with that complexity, specialision was still bad, very bad See https://gitlab.haskell.org/ghc/ghc/-/issues/19747#note_626297 And it's entirely unnecessary! Specialision works fine without unboxing tuple dictionaries. - - - - - be7296c9 by Andreas Klebinger at 2025-07-12T14:56:16+01:00 Remove complex special case from the type-class specialiser There was a pretty tricky special case in Specialise which is no longer necessary. * Historical Note [Floating dictionaries out of cases] * #26158 * #19747 https://gitlab.haskell.org/ghc/ghc/-/issues/19747#note_626297 This MR removes it. Hooray. - - - - - 4acf3a86 by Ben Gamari at 2025-07-15T05:46:32-04:00 configure: bump version to 9.15 - - - - - 45efaf71 by Teo Camarasu at 2025-07-15T05:47:13-04:00 rts/nonmovingGC: remove n_free We remove the nonmovingHeap.n_free variable. We wanted this to track the length of nonmovingHeap.free. But this isn't possible to do atomically. When this isn't accurate we can get a segfault by going past the end of the list. Instead, we just count the length of the list when we grab it in nonmovingPruneFreeSegment. Resolves #26186 - - - - - c635f164 by Ben Gamari at 2025-07-15T14:05:54-04:00 configure: Drop probing of ld.gold As noted in #25716, `gold` has been dropped from binutils-2.44. Fixes #25716. Metric Increase: size_hello_artifact_gzip size_hello_unicode_gzip ghc_prim_so - - - - - 637bb538 by Ben Gamari at 2025-07-15T14:05:55-04:00 testsuite/recomp015: Ignore stderr This is necessary since ld.bfd complains that we don't have a .note.GNU-stack section, potentially resulting in an executable stack. - - - - - d3cd4ec8 by Wen Kokke at 2025-07-15T14:06:39-04:00 Fix documentation for heap profile ID - - - - - 73082769 by Ben Gamari at 2025-07-15T16:56:38-04:00 Bump win32-tarballs to v0.9 - - - - - 3b63b254 by Ben Gamari at 2025-07-15T16:56:39-04:00 rts/LoadArchive: Handle null terminated string tables As of `llvm-ar` now emits filename tables terminated with null characters instead of the usual POSIX `/\n` sequence. Fixes #26150. - - - - - 195f6527 by Tamar Christina at 2025-07-15T16:56:39-04:00 rts: rename label so name doesn't conflict with param - - - - - 63373b95 by Tamar Christina at 2025-07-15T16:56:39-04:00 rts: Handle API set symbol versioning conflicts - - - - - 48e9aa3e by Tamar Christina at 2025-07-15T16:56:39-04:00 rts: Mark API set symbols as HIDDEN and correct symbol type - - - - - 959e827a by Tamar Christina at 2025-07-15T16:56:39-04:00 rts: Implement WEAK EXTERNAL undef redirection by target symbol name - - - - - 65f19293 by Ben Gamari at 2025-07-15T16:56:39-04:00 rts/LoadArchive: Handle string table entries terminated with / llvm-ar appears to terminate string table entries with `/\n` [1]. This matters in the case of thin archives, since the filename is used. In the past this worked since `llvm-ar` would produce archives with "small" filenames when possible. However, now it appears to always use the string table. [1] https://github.com/llvm/llvm-project/blob/bfb686bb5ba503e9386dc899e1ebbe2488... - - - - - 9cbb3ef5 by Ben Gamari at 2025-07-15T16:56:39-04:00 testsuite: Mark T12497 as fixed Thanks to the LLVM toolchain update. Closes #22694. - - - - - 2854407e by Ben Gamari at 2025-07-15T16:56:39-04:00 testsuite: Accept new output of T11223_link_order_a_b_2_fail on Windows The archive member number changed due to the fact that llvm-ar now uses a string table. - - - - - 28439593 by Ben Gamari at 2025-07-15T16:56:39-04:00 rts/linker/PEi386: Implement IMAGE_REL_AMD64_SECREL This appears to now be used by libc++ as distributed by msys2. - - - - - 2b053755 by Tamar Christina at 2025-07-15T16:56:39-04:00 rts: Cleanup merge resolution residue in lookupSymbolInDLL_PEi386 and make safe without dependent - - - - - e8acd2e7 by Wen Kokke at 2025-07-16T08:37:04-04:00 Remove the `profile_id` parameter from various RTS functions. Various RTS functions took a `profile_id` parameter, intended to be used to distinguish parallel heap profile breakdowns (e.g., `-hT` and `-hi`). However, this feature was never implemented and the `profile_id` parameter was set to 0 throughout the RTS. This commit removes the parameter but leaves the hardcoded profile ID in the functions that emit the encoded eventlog events as to not change the protocol. The affected functions are `traceHeapProfBegin`, `postHeapProfBegin`, `traceHeapProfSampleString`, `postHeapProfSampleString`, `traceHeapProfSampleCostCentre`, and `postHeapProfSampleCostCentre`. - - - - - 76d392a2 by Wen Kokke at 2025-07-16T08:37:04-04:00 Make `traceHeapProfBegin` an init event. - - - - - bbaa44a7 by Peng Fan at 2025-07-16T16:50:42-04:00 NCG/LA64: Support finer-grained DBAR hints For LA664 and newer uarchs, they have made finer granularity hints available: Bit4: ordering or completion (0: completion, 1: ordering) Bit3: barrier for previous read (0: true, 1: false) Bit2: barrier for previous write (0: true, 1: false) Bit1: barrier for succeeding read (0: true, 1: false) Bit0: barrier for succeeding write (0: true, 1: false) And not affect the existing models because other hints are treated as 'dbar 0' there. - - - - - 7da86e16 by Andreas Klebinger at 2025-07-16T16:51:25-04:00 Disable -fprof-late-overloaded-calls for join points. Currently GHC considers cost centres as destructive to join contexts. Or in other words this is not considered valid: join f x = ... in ... -> scc<tick> jmp This makes the functionality of `-fprof-late-overloaded-calls` not feasible for join points in general. We used to try to work around this by putting the ticks on the rhs of the join point rather than around the jump. However beyond the loss of accuracy this was broken for recursive join points as we ended up with something like: rec-join f x = scc<tick> ... jmp f x Which similarly is not valid as the tick once again destroys the tail call. One might think we could limit ourselves to non-recursive tail calls and do something clever like: join f x = scc<tick> ... in ... jmp f x And sometimes this works! But sometimes the full rhs would look something like: join g x = .... join f x = scc<tick> ... -> jmp g x Which, would again no longer be valid. I believe in the long run we can make cost centre ticks non-destructive to join points. Or we could keep track of where we are/are not allowed to insert a cost centre. But in the short term I will simply disable the annotation of join calls under this flag. - - - - - 7ee22fd5 by ARATA Mizuki at 2025-07-17T06:05:30-04:00 x86 NCG: Better lowering for shuffleFloatX4# and shuffleDoubleX2# The new implementation * make use of specialized instructions like (V)UNPCK{L,H}{PS,PD}, and * do not require -mavx. Close #26096 Co-authored-by: sheaf - - - - - c6cd2da1 by Jappie Klooster at 2025-07-17T06:06:20-04:00 Update interact docs to explain about buffering We need to tell the user to set to the appropriate buffer format. Otherwise, this function may get randomly stuck, or just behave confusingly. issue: https://gitlab.haskell.org/ghc/ghc/-/issues/26131 NB, I'm running this with cabal *NOT* ghci. ghci messes with buffering anyway. ```haskell interaction :: String -> String interaction "jappie" = "hi" interaction "jakob" = "hello" interaction x = "unkown input: " <> x main :: IO () main = interact interaction ``` so in my input (prefixed by `>`) I get: ```

jappie unkown input: jappie

we confirmed later this was due to lack of \n matching.
Anyway movnig on to more unexpected stuff:

```haskell
main :: IO ()
main = do
  interact  (concatMap interaction . lines)

get's stuck forever. actually `^D` (ctrl+d) unstucks it and runs all input as expected. for example you can get: ```

sdfkds fakdsf unkown input: sdfkdsunkown input: fakdsf

This program works!
```haskell
interaction :: String -> String
interaction "jappie" = "hi \n"
interaction "jakob" = "hello \n"
interaction x = "unkown input: " <> x <> "\n"

main :: IO ()
main = do
  interact  (concatMap interaction . lines)

the reason is that linebuffering is set for both in and output by default. so lines eats the input lines, and all the \n postfixes make sure the buffer is put out. - - - - - 9fa590a6 by Zubin Duggal at 2025-07-17T06:07:03-04:00 fetch_gitlab: Ensure we copy users_guide.pdf and Haddock.pdf to the release docs directory Fixes #24093 - - - - - cc650b4b by Andrew Lelechenko at 2025-07-17T12:30:24-04:00 Add Data.List.NonEmpty.mapMaybe As per https://github.com/haskell/core-libraries-committee/issues/337 - - - - - 360fa82c by Duncan Coutts at 2025-07-17T12:31:14-04:00 base: Deprecate GHC.Weak.Finalize.runFinalizerBatch https://github.com/haskell/core-libraries-committee/issues/342 - - - - - f4e8466c by Alan Zimmerman at 2025-07-17T12:31:55-04:00 EPA: Update exact printing based on GHC 9.14 tests As a result of migrating the GHC ghc-9.14 branch tests to ghc-exactprint in https://github.com/alanz/ghc-exactprint/tree/ghc-9.14, a couple of discrepancies were picked up - The opening paren for a DefaultDecl was printed in the wrong place - The import declaration level specifiers were not printed. This commit adds those fixes, and some tests for them. The tests brought to light that the ImportDecl ppr instance had not been updated for level specifiers, so it updates that too. - - - - - 8b731e3c by Matthew Pickering at 2025-07-21T13:36:43-04:00 level imports: Fix infinite loop with cyclic module imports I didn't anticipate that downsweep would run before we checked for cyclic imports. Therefore we need to use the reachability function which handles cyclic graphs. Fixes #26087 - - - - - d751a9f1 by Pierre Thierry at 2025-07-21T13:37:28-04:00 Fix documentation about deriving from generics - - - - - 9fcdca15 by Sebastian Graf at 2025-07-22T20:02:01+00:00 CprAnal: Detect recursive newtypes (#25944) While `cprTransformDataConWork` handles recursive data con workers, it did not detect the case when a newtype is responsible for the recursion. This is now detected in the `Cast` case of `cprAnal`. The same reproducer made it clear that `isRecDataCon` lacked congruent handling for `AppTy` and `CastTy`, now fixed. Furthermore, the new repro case T25944 triggered this bug via an infinite loop in `cprFix`, caused by the infelicity in `isRecDataCon`. While it should be much less likely to trigger such an infinite loop now that `isRecDataCon` has been fixed, I made sure to abort the loop after 10 iterations and emitting a warning instead. Fixes #25944. - - - - - 85 changed files: - .gitlab/rel_eng/fetch-gitlab-artifacts/fetch_gitlab.py - compiler/GHC/CmmToAsm/LA64/CodeGen.hs - compiler/GHC/CmmToAsm/LA64/Instr.hs - compiler/GHC/CmmToAsm/LA64/Ppr.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToAsm/X86/Instr.hs - compiler/GHC/CmmToAsm/X86/Ppr.hs - compiler/GHC/Core/LateCC/OverloadedCalls.hs - compiler/GHC/Core/Opt/CprAnal.hs - compiler/GHC/Core/Opt/DmdAnal.hs - compiler/GHC/Core/Opt/Specialise.hs - compiler/GHC/Core/Opt/WorkWrap/Utils.hs - compiler/GHC/Core/Predicate.hs - compiler/GHC/Hs/ImpExp.hs - compiler/GHC/Parser.y - compiler/GHC/Tc/Solver.hs - compiler/GHC/Tc/Solver/Dict.hs - compiler/GHC/Tc/Solver/InertSet.hs - compiler/GHC/Tc/Solver/Monad.hs - compiler/GHC/Tc/Utils/TcType.hs - compiler/GHC/Unit/Module/Graph.hs - configure.ac - docs/users_guide/9.14.1-notes.rst - docs/users_guide/eventlog-formats.rst - docs/users_guide/profiling.rst - libraries/base/changelog.md - libraries/base/src/Data/List/NonEmpty.hs - libraries/base/src/GHC/Generics.hs - libraries/base/src/GHC/Weak/Finalize.hs - libraries/ghc-internal/src/GHC/Internal/System/IO.hs - m4/find_ld.m4 - mk/get-win32-tarballs.py - rts/ProfHeap.c - rts/RetainerSet.c - rts/Trace.c - rts/Trace.h - rts/eventlog/EventLog.c - rts/eventlog/EventLog.h - rts/linker/LoadArchive.c - rts/linker/PEi386.c - rts/sm/NonMoving.c - rts/sm/NonMoving.h - rts/sm/NonMovingAllocate.c - rts/sm/Sanity.c - + testsuite/tests/cpranal/sigs/T25944.hs - + testsuite/tests/cpranal/sigs/T25944.stderr - testsuite/tests/cpranal/sigs/all.T - testsuite/tests/dmdanal/should_compile/T23398.hs - testsuite/tests/dmdanal/should_compile/T23398.stderr - testsuite/tests/driver/recomp015/all.T - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 - + testsuite/tests/perf/should_run/SpecTyFamRun.hs - + testsuite/tests/perf/should_run/SpecTyFamRun.stdout - + testsuite/tests/perf/should_run/SpecTyFam_Import.hs - testsuite/tests/perf/should_run/all.T - testsuite/tests/printer/Makefile - + testsuite/tests/printer/TestLevelImports.hs - + testsuite/tests/printer/TestNamedDefaults.hs - testsuite/tests/printer/all.T - testsuite/tests/rts/all.T - testsuite/tests/rts/linker/T11223/T11223_link_order_a_b_2_fail.stderr-ws-32-mingw32 - testsuite/tests/rts/linker/T11223/T11223_link_order_a_b_2_fail.stderr-ws-64-mingw32 - testsuite/tests/simd/should_run/all.T - + testsuite/tests/simd/should_run/doublex2_shuffle.hs - + testsuite/tests/simd/should_run/doublex2_shuffle.stdout - + testsuite/tests/simd/should_run/doublex2_shuffle_baseline.hs - + testsuite/tests/simd/should_run/doublex2_shuffle_baseline.stdout - + testsuite/tests/simd/should_run/floatx4_shuffle.hs - + testsuite/tests/simd/should_run/floatx4_shuffle.stdout - + testsuite/tests/simd/should_run/floatx4_shuffle_baseline.hs - + testsuite/tests/simd/should_run/floatx4_shuffle_baseline.stdout - + testsuite/tests/simplCore/should_compile/T26051.hs - + testsuite/tests/simplCore/should_compile/T26051.stderr - + testsuite/tests/simplCore/should_compile/T26051_Import.hs - testsuite/tests/simplCore/should_compile/all.T - + testsuite/tests/splice-imports/T26087.stderr - + testsuite/tests/splice-imports/T26087A.hs - + testsuite/tests/splice-imports/T26087B.hs - testsuite/tests/splice-imports/all.T - utils/check-exact/ExactPrint.hs - utils/ghc-toolchain/src/GHC/Toolchain/Tools/Link.hs - utils/haddock/haddock-api/haddock-api.cabal The diff was not included because it is too large. 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