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[Git][ghc/ghc][master] Hadrian: convert env variable ACLOCAL_PATH to unix paths.
by Marge Bot (＠marge-bot) 05 Jun '26

05 Jun '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: a3b431f3 by David Eichmann at 2026-06-04T10:10:19+00:00 Hadrian: convert env variable ACLOCAL_PATH to unix paths. Convert ACLOCAL_PATH to a unix style path when invoking autoreconf. Autoreconf doesn't handle windows paths. See Note [Autoreconf unix paths from ACLOCAL_PATH]. Fixes #27311 - - - - - 3 changed files: - boot - hadrian/src/Hadrian/Oracles/Path.hs - hadrian/src/Rules/BinaryDist.hs Changes: ===================================== boot ===================================== @@ -52,9 +52,8 @@ def autoreconf(): # Run autoreconf on everything that needs it. processes = {} if os.name == 'nt': - # Get the normalized ACLOCAL_PATH for Windows - # This is necessary since on Windows this will be a Windows - # path, which autoreconf doesn't know doesn't know how to handle. + # Convert ACLOCAL_PATH env variable to unix style paths on Windows + # See Note [Autoreconf unix paths from ACLOCAL_PATH] ac_local = os.getenv('ACLOCAL_PATH', '') ac_local_arg = re.sub(r';', r':', ac_local) ac_local_arg = re.sub(r'\\', r'/', ac_local_arg) ===================================== hadrian/src/Hadrian/Oracles/Path.hs ===================================== @@ -1,6 +1,7 @@ {-# LANGUAGE TypeFamilies #-} module Hadrian.Oracles.Path ( - lookupInPath, fixAbsolutePathOnWindows, pathOracle + lookupInPath, fixAbsolutePathOnWindows, fixUnixPathsOnWindows, + pathOracle ) where import Control.Monad @@ -33,6 +34,14 @@ fixAbsolutePathOnWindows path = else return path +-- | Fix a unix path list on Windows: +-- * "C:\\foo\\bar;C:\\msys2\\bin" => "/c/foo/bar:/c/msys2/bin" +fixUnixPathsOnWindows :: FilePath -> Action FilePath +fixUnixPathsOnWindows paths = + if isWindows + then askOracle $ UnixPathList paths + else return paths + newtype LookupInPath = LookupInPath String deriving (Binary, Eq, Hashable, NFData, Show) type instance RuleResult LookupInPath = String @@ -41,6 +50,10 @@ newtype WindowsPath = WindowsPath FilePath deriving (Binary, Eq, Hashable, NFData, Show) type instance RuleResult WindowsPath = String +newtype UnixPathList = UnixPathList FilePath + deriving (Binary, Eq, Hashable, NFData, Show) +type instance RuleResult UnixPathList = String + -- | Oracles for looking up paths. These are slow and require caching. pathOracle :: Rules () pathOracle = do @@ -50,6 +63,12 @@ pathOracle = do putVerbose $ "| Windows path mapping: " ++ path ++ " => " ++ windowsPath return windowsPath + void $ addOracleCache $ \(UnixPathList paths) -> do + Stdout out <- quietly $ cmd ["cygpath", "-p", "-u", paths] + let unixPaths = unifyPath $ dropWhileEnd isSpace out + putVerbose $ "| Unix path mapping: " ++ paths ++ " => " ++ unixPaths + return unixPaths + void $ addOracleCache $ \(LookupInPath name) -> do path <- liftIO getSearchPath exes <- liftIO (findExecutablesInDirectories path name) ===================================== hadrian/src/Rules/BinaryDist.hs ===================================== @@ -3,18 +3,19 @@ module Rules.BinaryDist where import CommandLine import Context +import Data.Either +import qualified Data.Set as Set import Expression +import Hadrian.Oracles.Path (fixUnixPathsOnWindows) +import Oracles.Flavour import Oracles.Setting import Packages +import Rules.Generate (generateSettings) import Settings +import qualified System.Directory.Extra as IO import Settings.Program (programContext) import Target import Utilities -import qualified System.Directory.Extra as IO -import Data.Either -import qualified Data.Set as Set -import Oracles.Flavour -import Rules.Generate (generateSettings) {- Note [Binary distributions] @@ -343,7 +344,25 @@ bindistRules = do ghcRoot <- topDirectory copyFile (ghcRoot -/- "aclocal.m4") (ghcRoot -/- "distrib" -/- "aclocal.m4") copyDirectory (ghcRoot -/- "m4") (ghcRoot -/- "distrib") - buildWithCmdOptions [] $ + + -- Note [Autoreconf unix paths from ACLOCAL_PATH] + -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + -- On Windows, autoreconf fails when the ACLOCAL_PATH env variable contains Windows- + -- style paths. This happens because MSYS2 automatically converts env variables to + -- Windows-style paths. To fix this, we convert ACLOCAL_PATH back to Unix style. + -- This is done both in the boot Python script and here when building a bindist. + win_host <- isWinHost + env <- if not win_host + then pure [] + else do + aclocalPathMay <- getEnv "ACLOCAL_PATH" + case aclocalPathMay of + Nothing -> pure [] + Just aclocalPath -> do + unixAclocalPath <- fixUnixPathsOnWindows aclocalPath + pure [AddEnv "ACLOCAL_PATH" unixAclocalPath] + + buildWithCmdOptions env $ target (vanillaContext Stage1 ghc) (Autoreconf $ ghcRoot -/- "distrib") [] [] -- We clean after ourselves, moving the configure script we generated in -- our bindist dir View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a3b431f3cb46f4c23f7401ca195afe3… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/a3b431f3cb46f4c23f7401ca195afe3… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 2 commits: Hadrian: convert env variable ACLOCAL_PATH to unix paths.
by Marge Bot (＠marge-bot) 04 Jun '26

04 Jun '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: a3b431f3 by David Eichmann at 2026-06-04T10:10:19+00:00 Hadrian: convert env variable ACLOCAL_PATH to unix paths. Convert ACLOCAL_PATH to a unix style path when invoking autoreconf. Autoreconf doesn't handle windows paths. See Note [Autoreconf unix paths from ACLOCAL_PATH]. Fixes #27311 - - - - - fcfa0834 by Simon Jakobi at 2026-06-04T16:19:21-04:00 testsuite: Deduplicate --only test names config.only is assumed to be a set, but supplying --only overwrote it with the (list) argparse result, which can contain duplicates. When a test ran, config.only.remove(name) dropped only the first occurrence, so a duplicated name lingered and was later misreported as a "test not found" framework failure. Store it as a set instead. Fixes #27322 Co-Authored-By: Claude Opus 4.7 <noreply(a)anthropic.com> - - - - - 4 changed files: - boot - hadrian/src/Hadrian/Oracles/Path.hs - hadrian/src/Rules/BinaryDist.hs - testsuite/driver/runtests.py Changes: ===================================== boot ===================================== @@ -52,9 +52,8 @@ def autoreconf(): # Run autoreconf on everything that needs it. processes = {} if os.name == 'nt': - # Get the normalized ACLOCAL_PATH for Windows - # This is necessary since on Windows this will be a Windows - # path, which autoreconf doesn't know doesn't know how to handle. + # Convert ACLOCAL_PATH env variable to unix style paths on Windows + # See Note [Autoreconf unix paths from ACLOCAL_PATH] ac_local = os.getenv('ACLOCAL_PATH', '') ac_local_arg = re.sub(r';', r':', ac_local) ac_local_arg = re.sub(r'\\', r'/', ac_local_arg) ===================================== hadrian/src/Hadrian/Oracles/Path.hs ===================================== @@ -1,6 +1,7 @@ {-# LANGUAGE TypeFamilies #-} module Hadrian.Oracles.Path ( - lookupInPath, fixAbsolutePathOnWindows, pathOracle + lookupInPath, fixAbsolutePathOnWindows, fixUnixPathsOnWindows, + pathOracle ) where import Control.Monad @@ -33,6 +34,14 @@ fixAbsolutePathOnWindows path = else return path +-- | Fix a unix path list on Windows: +-- * "C:\\foo\\bar;C:\\msys2\\bin" => "/c/foo/bar:/c/msys2/bin" +fixUnixPathsOnWindows :: FilePath -> Action FilePath +fixUnixPathsOnWindows paths = + if isWindows + then askOracle $ UnixPathList paths + else return paths + newtype LookupInPath = LookupInPath String deriving (Binary, Eq, Hashable, NFData, Show) type instance RuleResult LookupInPath = String @@ -41,6 +50,10 @@ newtype WindowsPath = WindowsPath FilePath deriving (Binary, Eq, Hashable, NFData, Show) type instance RuleResult WindowsPath = String +newtype UnixPathList = UnixPathList FilePath + deriving (Binary, Eq, Hashable, NFData, Show) +type instance RuleResult UnixPathList = String + -- | Oracles for looking up paths. These are slow and require caching. pathOracle :: Rules () pathOracle = do @@ -50,6 +63,12 @@ pathOracle = do putVerbose $ "| Windows path mapping: " ++ path ++ " => " ++ windowsPath return windowsPath + void $ addOracleCache $ \(UnixPathList paths) -> do + Stdout out <- quietly $ cmd ["cygpath", "-p", "-u", paths] + let unixPaths = unifyPath $ dropWhileEnd isSpace out + putVerbose $ "| Unix path mapping: " ++ paths ++ " => " ++ unixPaths + return unixPaths + void $ addOracleCache $ \(LookupInPath name) -> do path <- liftIO getSearchPath exes <- liftIO (findExecutablesInDirectories path name) ===================================== hadrian/src/Rules/BinaryDist.hs ===================================== @@ -3,18 +3,19 @@ module Rules.BinaryDist where import CommandLine import Context +import Data.Either +import qualified Data.Set as Set import Expression +import Hadrian.Oracles.Path (fixUnixPathsOnWindows) +import Oracles.Flavour import Oracles.Setting import Packages +import Rules.Generate (generateSettings) import Settings +import qualified System.Directory.Extra as IO import Settings.Program (programContext) import Target import Utilities -import qualified System.Directory.Extra as IO -import Data.Either -import qualified Data.Set as Set -import Oracles.Flavour -import Rules.Generate (generateSettings) {- Note [Binary distributions] @@ -343,7 +344,25 @@ bindistRules = do ghcRoot <- topDirectory copyFile (ghcRoot -/- "aclocal.m4") (ghcRoot -/- "distrib" -/- "aclocal.m4") copyDirectory (ghcRoot -/- "m4") (ghcRoot -/- "distrib") - buildWithCmdOptions [] $ + + -- Note [Autoreconf unix paths from ACLOCAL_PATH] + -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + -- On Windows, autoreconf fails when the ACLOCAL_PATH env variable contains Windows- + -- style paths. This happens because MSYS2 automatically converts env variables to + -- Windows-style paths. To fix this, we convert ACLOCAL_PATH back to Unix style. + -- This is done both in the boot Python script and here when building a bindist. + win_host <- isWinHost + env <- if not win_host + then pure [] + else do + aclocalPathMay <- getEnv "ACLOCAL_PATH" + case aclocalPathMay of + Nothing -> pure [] + Just aclocalPath -> do + unixAclocalPath <- fixUnixPathsOnWindows aclocalPath + pure [AddEnv "ACLOCAL_PATH" unixAclocalPath] + + buildWithCmdOptions env $ target (vanillaContext Stage1 ghc) (Autoreconf $ ghcRoot -/- "distrib") [] [] -- We clean after ourselves, moving the configure script we generated in -- our bindist dir ===================================== testsuite/driver/runtests.py ===================================== @@ -133,7 +133,7 @@ if args.unexpected_output_dir: config.unexpected_output_dir = Path(args.unexpected_output_dir) if args.only: - config.only = args.only + config.only = set(args.only) config.run_only_some_tests = True if args.skip: View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/e834d92ab335c45f940995570181bd… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/e834d92ab335c45f940995570181bd… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/fix-26953] Decoupling 'L.H.S' from 'GHC.Types.SourceText'
by recursion-ninja (＠recursion-ninja) 04 Jun '26

04 Jun '26

recursion-ninja pushed to branch wip/fix-26953 at Glasgow Haskell Compiler / GHC Commits: 7f137110 by Recursion Ninja at 2026-06-04T13:45:40-04:00 Decoupling 'L.H.S' from 'GHC.Types.SourceText' * Migrated 'IntegralLit' to 'L.H.S.Lit'. * Migrated 'FractionalLit' to 'L.H.S.Lit'. * Migrated 'StringLiteral' to 'L.H.S.Lit'. * Added TTG extension points to the types above. * Added nice export list to 'GHC.Hs.Lit'. * Added 'rnOverLitVal' and 'tcOverLitVal' functions to 'GHC.Hs.Lit'. * Added instance 'Anno (StringLiteral (GhcPass p)) = SrcSpanAnnN' * Moved [Notes] about 'SourceText' from 'L.H.S.*' to 'GHC.*'. * Removed all references to 'SourceText' from 'L.H.S'. * Removed the trailing comma record field from 'StringLiteral' * Renamed exported functions for nomenclature consistency. * Deprecated the renamed functions Resolves issue #26953 - - - - - 62 changed files: - compiler/GHC/Builtin/Utils.hs - compiler/GHC/CmmToAsm/BlockLayout.hs - compiler/GHC/Driver/Backpack.hs - compiler/GHC/Driver/Session/Units.hs - compiler/GHC/Hs/Binds.hs - compiler/GHC/Hs/Decls.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Hs/Instances.hs - compiler/GHC/Hs/Lit.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Match.hs - compiler/GHC/HsToCore/Match/Literal.hs - compiler/GHC/HsToCore/Pmc/Desugar.hs - compiler/GHC/HsToCore/Pmc/Solver/Types.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/HsToCore/Usage.hs - compiler/GHC/Iface/Syntax.hs - compiler/GHC/Iface/Warnings.hs - compiler/GHC/Linker/Unit.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/HaddockLex.x - compiler/GHC/Parser/Lexer.x - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Rename/Bind.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/HsType.hs - compiler/GHC/Rename/Lit.hs - compiler/GHC/Rename/Module.hs - compiler/GHC/Rename/Names.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/Rename/Utils.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Gen/Bind.hs - compiler/GHC/Tc/Gen/Head.hs - compiler/GHC/Tc/Gen/HsType.hs - compiler/GHC/Tc/Utils/Instantiate.hs - compiler/GHC/Tc/Utils/TcMType.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Types/PkgQual.hs - compiler/GHC/Types/SourceText.hs - compiler/GHC/Unit/Info.hs - compiler/GHC/Unit/Module/Warnings.hs - compiler/GHC/Unit/State.hs - compiler/GHC/Utils/Misc.hs - compiler/Language/Haskell/Syntax/Binds.hs - compiler/Language/Haskell/Syntax/Binds/InlinePragma.hs - compiler/Language/Haskell/Syntax/Decls.hs - compiler/Language/Haskell/Syntax/Decls/Foreign.hs - compiler/Language/Haskell/Syntax/Expr.hs - compiler/Language/Haskell/Syntax/Extension.hs - compiler/Language/Haskell/Syntax/Lit.hs - testsuite/tests/ghc-api/annotations-literals/literals.stdout - testsuite/tests/ghc-api/annotations-literals/parsed.hs - utils/check-exact/ExactPrint.hs - utils/haddock/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs - utils/haddock/haddock-api/src/Haddock/Backends/LaTeX.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs - utils/haddock/haddock-api/src/Haddock/Interface/LexParseRn.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Types.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/7f137110501e4e06a7c039057817a07… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/7f137110501e4e06a7c039057817a07… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 2 commits: Fix AArch64 clobbering bug for MUL2
by Marge Bot (＠marge-bot) 04 Jun '26

04 Jun '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: c2989784 by sheaf at 2026-06-04T13:07:45-04:00 Fix AArch64 clobbering bug for MUL2 On AArch64, the code generator could clobber one of the input operands when computing the lower bits of a MUL2 operation. This rendered invalid the subsequent computation of the high bits. This commit fixes that by using a temporary register. The register allocator can remove the redundant move in the common case when the registers do not conflict. Fixes #27046 - - - - - e834d92a by Simon Jakobi at 2026-06-04T13:07:46-04:00 testsuite: Deduplicate --only test names config.only is assumed to be a set, but supplying --only overwrote it with the (list) argparse result, which can contain duplicates. When a test ran, config.only.remove(name) dropped only the first occurrence, so a duplicated name lingered and was later misreported as a "test not found" framework failure. Store it as a set instead. Fixes #27322 Co-Authored-By: Claude Opus 4.7 <noreply(a)anthropic.com> - - - - - 6 changed files: - + changelog.d/T27046 - compiler/GHC/CmmToAsm/AArch64/CodeGen.hs - testsuite/driver/runtests.py - + testsuite/tests/codeGen/should_run/T27046.hs - + testsuite/tests/codeGen/should_run/T27046_cmm.cmm - testsuite/tests/codeGen/should_run/all.T Changes: ===================================== changelog.d/T27046 ===================================== @@ -0,0 +1,9 @@ +section: compiler +issues: #27046 +mrs: !16031 +synopsis: + Avoid AArch64 register clobbering bug in MUL2 +description: + Fixes an issue in which, on AArch64, code generation for the MUL2 operation + could clobber one of the input operands when computing the lower bits, which + rendered invalid the subsequent computation of the high bits. ===================================== compiler/GHC/CmmToAsm/AArch64/CodeGen.hs ===================================== @@ -2300,11 +2300,19 @@ genCCall target dest_regs arg_regs = do let lo = getRegisterReg platform (CmmLocal dst_lo) hi = getRegisterReg platform (CmmLocal dst_hi) nd = getRegisterReg platform (CmmLocal dst_needed) + + -- Generate a fresh virtual register for the low word computation. + -- This avoids clobbering reg_a or reg_b in the first MUL instruction, + -- which could for example happen if 'lo' and 'reg_a' are the same + -- virtual register. + tmp_lo <- getNewRegNat II64 + return $ code_x `appOL` code_y `snocOL` - MUL II64 (OpReg W64 lo) (OpReg W64 reg_a) (OpReg W64 reg_b) `snocOL` + MUL II64 (OpReg W64 tmp_lo) (OpReg W64 reg_a) (OpReg W64 reg_b) `snocOL` SMULH (OpReg W64 hi) (OpReg W64 reg_a) (OpReg W64 reg_b) `snocOL` + MOV (OpReg W64 lo) (OpReg W64 tmp_lo) `snocOL` -- Are all high bits equal to the sign bit of the low word? -- nd = (hi == ASR(lo,width-1)) ? 1 : 0 CMP (OpReg W64 hi) (OpRegShift W64 lo SASR (widthInBits w - 1)) `snocOL` ===================================== testsuite/driver/runtests.py ===================================== @@ -133,7 +133,7 @@ if args.unexpected_output_dir: config.unexpected_output_dir = Path(args.unexpected_output_dir) if args.only: - config.only = args.only + config.only = set(args.only) config.run_only_some_tests = True if args.skip: ===================================== testsuite/tests/codeGen/should_run/T27046.hs ===================================== @@ -0,0 +1,29 @@ +{-# LANGUAGE MagicHash #-} +{-# LANGUAGE ForeignFunctionInterface, GHCForeignImportPrim, UnliftedFFITypes #-} + +module Main where + +import Control.Monad + ( unless ) +import Data.Bits + ( shiftL ) +import GHC.Exts + ( Int64# ) +import GHC.Int + ( Int64(..) ) + +foreign import prim "test_mul2_clobber" + test_mul2_clobber :: Int64# -> Int64# -> Int64# + +main :: IO () +main = do + let + I64# x = 1 `shiftL` 32 + hi = I64# $ test_mul2_clobber x x + + unless ( hi == 1 ) $ + error $ unlines + [ "Incorrect result for Mul2 operation." + , "Expected high word: 1" + , " Actual high word: " ++ show hi + ] ===================================== testsuite/tests/codeGen/should_run/T27046_cmm.cmm ===================================== @@ -0,0 +1,13 @@ +#include "Cmm.h" + +// Test for #27046 +test_mul2_clobber (bits64 x, bits64 y) +{ + bits64 hi, nd; + + // Deliberately alias the destination 'lo' with the source 'x' + // This forces the NCG to use the same virtual register for both. + (nd, hi, x) = prim %mul2_64(x, y); + + return (hi); +} ===================================== testsuite/tests/codeGen/should_run/all.T ===================================== @@ -260,6 +260,7 @@ test('T25364', normal, compile_and_run, ['']) test('T26061', normal, compile_and_run, ['']) test('T26537', normal, compile_and_run, ['-O2 -fregs-graph']) test('T24016', normal, compile_and_run, ['-O1 -fPIC']) +test('T27046', [req_cmm], compile_and_run, ['T27046_cmm.cmm']) # Check that GHC-generated finalizers run on Darwin. The Apple linker doesn't # support --wrap, so we can't intercept hs_spt_remove directly. Instead we View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c19aa850a1a18161cfb25ecf4781fa… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c19aa850a1a18161cfb25ecf4781fa… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/davide/hadrian_avoid_response_files_2] Hadrian: always keep response files
by David Eichmann (＠DavidEichmann) 04 Jun '26

04 Jun '26

David Eichmann pushed to branch wip/davide/hadrian_avoid_response_files_2 at Glasgow Haskell Compiler / GHC Commits: ea8b402a by David Eichmann at 2026-06-04T16:04:59+01:00 Hadrian: always keep response files Now that response files are only used in a small number of cases, it's reasonable to keep all response files by default and simply remove the -r / --keep-response-files command line options. The response file paths are nolonger randomized. They are placed in the `_build/rsp` directory. This ensures we reuse file paths when rebuilding rather than leaving stale response files around. - - - - - 5 changed files: - − changelog.d/hadrian-response-files.md - hadrian/src/Builder.hs - hadrian/src/CommandLine.hs - hadrian/src/Hadrian/Builder/Ar.hs - hadrian/src/Hadrian/Utilities.hs Changes: ===================================== changelog.d/hadrian-response-files.md deleted ===================================== @@ -1,9 +0,0 @@ -section: packaging -synopsis: Add a flag to tell Hadrian to keep response files -issues: #27184 -mrs: !15906 -description: - Hadrian can now be instructed to keep response files with the new - --keep-response-files command line flag. This is helpful when debugging a - build failure, as it allows re-running the failing command line invocation - without an error due to a missing response file. ===================================== hadrian/src/Builder.hs ===================================== @@ -304,7 +304,7 @@ instance H.Builder Builder where case builder of Ar Pack stg -> do useTempFile <- arSupportsAtFile stg - if useTempFile then runAr path buildArgs buildInputs buildOptions + if useTempFile then runAr output path buildArgs buildInputs buildOptions else runArWithoutTempFile path buildArgs buildInputs buildOptions Ar Unpack _ -> cmd' [Cwd output] [path] buildArgs buildOptions @@ -343,7 +343,7 @@ instance H.Builder Builder where Exit _ <- cmd' [path] (buildArgs ++ [input]) buildOptions return () - Haddock BuildPackage -> runHaddock path buildArgs buildInputs + Haddock BuildPackage -> runHaddock output path buildArgs buildInputs Ghc _ _ -> -- Use a response file for ghc invocations to avoid issues with command line @@ -352,6 +352,7 @@ instance H.Builder Builder where -- empty arguments (such as the -dep-suffix flag), but that isn't supported -- yet due to #26560. withResponseFileIfLongCmd + output (toCmdArgument [path] <> toCmdArgument buildArgs) buildInputs (toCmdArgument buildOptions) @@ -390,11 +391,13 @@ instance H.Builder Builder where -- | Invoke @haddock@ given a path to it and a list of arguments. On Windows, -- the input file arguments are passed as a response file. -runHaddock :: FilePath -- ^ path to @haddock@ +runHaddock :: FilePath -- ^ base name to use for response file + -> FilePath -- ^ path to @haddock@ -> [String] -> [FilePath] -- ^ input file paths -> Action () -runHaddock haddockPath flagArgs fileInputs = withResponseFileIfLongCmd +runHaddock outputFilePath haddockPath flagArgs fileInputs = withResponseFileIfLongCmd + outputFilePath (toCmdArgument [haddockPath] <> toCmdArgument flagArgs) fileInputs (CmdArgument []) ===================================== hadrian/src/CommandLine.hs ===================================== @@ -3,8 +3,7 @@ module CommandLine ( lookupBignum, cmdBignum, cmdProgressInfo, cmdCompleteSetting, cmdDocsArgs, cmdUnitIdHash, lookupBuildRoot, TestArgs(..), TestSpeed(..), defaultTestArgs, - cmdPrefix, cmdChangelogVersion, DocArgs(..), defaultDocArgs, - cmdKeepResponseFiles + cmdPrefix, cmdChangelogVersion, DocArgs(..), defaultDocArgs ) where import Data.Either @@ -12,7 +11,7 @@ import qualified Data.HashMap.Strict as Map import Data.List.Extra import Development.Shake hiding (Normal) import Flavour (DocTargets, DocTarget(..)) -import Hadrian.Utilities hiding (buildRoot, keepResponseFiles) +import Hadrian.Utilities hiding (buildRoot) import Settings.Parser import System.Console.GetOpt import System.Environment @@ -37,7 +36,6 @@ data CommandLineArgs = CommandLineArgs , testArgs :: TestArgs , docsArgs :: DocArgs , docTargets :: DocTargets - , keepResponseFiles :: Bool , prefix :: Maybe FilePath , changelogVersion :: Maybe String , completeStg :: Maybe String } @@ -58,7 +56,6 @@ defaultCommandLineArgs = CommandLineArgs , testArgs = defaultTestArgs , docsArgs = defaultDocArgs , docTargets = Set.fromList [minBound..maxBound] - , keepResponseFiles = False , prefix = Nothing , changelogVersion = Nothing , completeStg = Nothing } @@ -141,9 +138,6 @@ readFreeze1 = Right $ \flags -> flags { freeze1 = True } readFreeze2 = Right $ \flags -> flags { freeze1 = True, freeze2 = True } readSkipDepends = Right $ \flags -> flags { skipDepends = True } -readKeepResponseFiles :: Either String (CommandLineArgs -> CommandLineArgs) -readKeepResponseFiles = Right $ \flags -> flags { keepResponseFiles = True } - readUnitIdHash :: Either String (CommandLineArgs -> CommandLineArgs) readUnitIdHash = Right $ \flags -> trace "--hash-unit-ids is deprecated. It is enabled by release flavour or +hash_unit_ids flavour transformer" $ @@ -302,8 +296,6 @@ optDescrs = "Progress info style (None, Brief, Normal or Unicorn)." , Option [] ["docs"] (ReqArg readDocsArg "TARGET") "Strip down docs targets (none, no-haddocks, no-sphinx[-{html, pdfs, man}]." - , Option ['r'] ["keep-response-files"] (NoArg readKeepResponseFiles) - "Keep response files created during the build (for debugging)." , Option ['k'] ["keep-test-files"] (NoArg readTestKeepFiles) "Keep all the files generated when running the testsuite." , Option [] ["test-compiler"] (ReqArg readTestCompiler "TEST_COMPILER") @@ -382,7 +374,6 @@ cmdLineArgsMap = do return $ insertExtra (progressInfo args) -- Accessed by Hadrian.Utilities $ insertExtra (buildRoot args) -- Accessed by Hadrian.Utilities - $ insertExtra (KeepResponseFiles $ keepResponseFiles args) -- Accessed by Hadrian.Utilities $ insertExtra (testArgs args) -- Accessed by Settings.Builders.RunTest $ insertExtra (docsArgs args) -- Accessed by Rules.Documentation $ insertExtra allSettings -- Accessed by Settings @@ -424,9 +415,6 @@ cmdUnitIdHash = unitIdHash <$> cmdLineArgs cmdBignum :: Action (Maybe String) cmdBignum = bignum <$> cmdLineArgs -cmdKeepResponseFiles :: Action Bool -cmdKeepResponseFiles = keepResponseFiles <$> cmdLineArgs - cmdProgressInfo :: Action ProgressInfo cmdProgressInfo = progressInfo <$> cmdLineArgs ===================================== hadrian/src/Hadrian/Builder/Ar.hs ===================================== @@ -35,14 +35,16 @@ instance NFData ArMode -- to be archived is passed via a temporary response file. Passing arguments -- via a response file is not supported by some versions of @ar@, in which -- case you should use 'runArWithoutTempFile' instead. -runAr :: FilePath -- ^ path to @ar@ +runAr :: FilePath -- ^ base name to use for response files + -> FilePath -- ^ path to @ar@ -> [String] -- ^ other arguments -> [FilePath] -- ^ input file paths -> [CmdOption] -- ^ Additional options -> Action () -runAr arPath flagArgs fileArgs buildOptions = withResponseFile $ \tmp -> do - writeFile' tmp $ unwords fileArgs - cmd [arPath] flagArgs ('@' : tmp) buildOptions +runAr outputFilePath arPath flagArgs fileArgs buildOptions = do + rspFile <- responseFilePath outputFilePath + writeFile' rspFile $ unwords fileArgs + cmd [arPath] flagArgs ('@' : rspFile) buildOptions -- | Invoke @ar@ given a path to it and a list of arguments. Note that @ar@ -- will be called multiple times if the list of files to be archived is too ===================================== hadrian/src/Hadrian/Utilities.hs ===================================== @@ -16,7 +16,7 @@ module Hadrian.Utilities ( -- * Paths BuildRoot (..), buildRoot, buildRootRules, isGeneratedSource, - KeepResponseFiles (..), keepResponseFiles, withResponseFile, withResponseFileIfLongCmd, + withResponseFileIfLongCmd, responseFilePath, -- * File system operations copyFile, copyFileUntracked, createFileLink, fixFile, @@ -49,10 +49,10 @@ import Data.Maybe import Data.Typeable (TypeRep, typeOf) import Development.Shake hiding (Normal) import Development.Shake.Classes +import Development.Shake.Command (CmdArgument (..), IsCmdArgument (toCmdArgument)) import Development.Shake.FilePath import GHC.ResponseFile (escapeArgs) import System.Environment (lookupEnv) -import System.IO (hClose, openTempFile) import System.IO.Error (isPermissionError) import qualified Data.ByteString as BS @@ -62,7 +62,6 @@ import qualified System.Directory.Extra as IO import qualified System.Info.Extra as IO import qualified System.IO as IO import qualified System.FilePath.Posix as Posix -import Development.Shake.Command (CmdArgument (..), IsCmdArgument (toCmdArgument)) -- | Extract a value from a singleton list, or terminate with an error message -- if the list does not contain exactly one value. @@ -257,13 +256,13 @@ infix 1 %%> -- library, they can reach 2MB! Some operating systems do not support command -- lines of such length, and this function can be used to obtain a reasonable -- approximation of the limit. On Windows, it is theoretically 32768 characters --- (since Windows 7). In practice we use 31000 to leave some breathing space for +-- (since Windows 7). In practice we use 30000 to leave some breathing space for -- the builder path & name, auxiliary flags, and other overheads. On Mac OS X, -- ARG_MAX is 262144, yet when using @xargs@ on OSX this is reduced by over -- 20000. Hence, 200000 seems like a sensible limit. On other operating systems -- we currently use the 4194304 setting. cmdLineLengthLimit :: Int -cmdLineLengthLimit | IO.isWindows = 31000 +cmdLineLengthLimit | IO.isWindows = 30000 | IO.isMac = 200000 | otherwise = 4194304 @@ -323,59 +322,35 @@ buildRootRules = do isGeneratedSource :: FilePath -> Action Bool isGeneratedSource file = buildRoot <&> (`isPrefixOf` file) -newtype KeepResponseFiles = KeepResponseFiles Bool deriving (Eq, Show) - --- | Whether to retain response files after the build action that created them --- completes. Mainly useful for debugging. -keepResponseFiles :: Action Bool -keepResponseFiles = do - KeepResponseFiles keep <- userSetting (KeepResponseFiles False) - return keep - -- | Run an command with the given arguments. If the command is too long then the -- response file arguments are placed into a response file and escaped with @GHC.ResponseFile.escapeArgs@. --- --- With @--keep-response-files@, the file is left on disk (if used) -withResponseFileIfLongCmd :: (CmdResult c) => - CmdArgument -- ^ Command and arguments before the response file arguments. +withResponseFileIfLongCmd :: + CmdResult c + => FilePath -- ^ Response base name. The reponse file is placed in @_build/rsp/\<Response base name\>@. + -> CmdArgument -- ^ Command and arguments before the response file arguments. -> [String] -- ^ Response file aruguments. -> CmdArgument -- ^ Command arguments after the response file arguments. -> Action c -withResponseFileIfLongCmd argsPre argsResp argsPost = do +withResponseFileIfLongCmd outputFilePath argsPre argsResp argsPost = do let cmdLineLengh = sum [ 1 + length arg -- add one to account for space inbetween arguments | let CmdArgument args = argsPre <> toCmdArgument argsResp <> argsPost , Right arg <- args ] - if cmdLineLengh >= cmdLineLengthLimit - then withResponseFile $ \tmp -> do - writeFile' tmp (escapeArgs argsResp) - cmd argsPre ['@' : tmp] argsPost - else cmd argsPre argsResp argsPost - --- | Run an action with a response file path. --- --- With @--keep-response-files@, the file is left on disk. -withResponseFile :: (FilePath -> Action a) -> Action a -withResponseFile action = do - keep <- keepResponseFiles - let putVerboseResponseFile tmp = do - verbosity <- getVerbosity - when (verbosity >= Verbose) $ do - tmpContent <- liftIO (readFile tmp) - putVerbose (tmp <> " (use hadrian flag --keep-response-files to keep this file):\n" <> tmpContent) - if keep - then do - (tmp, h) <- liftIO $ openTempFile "." "hadrian-rsp" - liftIO $ hClose h - putInfo $ "Keeping response file: " ++ tmp - result <- action tmp - putVerboseResponseFile tmp - return result - else withTempFile $ \tmp -> do - result <- action tmp - putVerboseResponseFile tmp - return result + if cmdLineLengh < cmdLineLengthLimit + then cmd argsPre argsResp argsPost + else do + rspFile <- responseFilePath outputFilePath + writeFile' rspFile (escapeArgs argsResp) + cmd argsPre ['@' : rspFile] argsPost + +-- | Convert a command's output file path to a response file path to be used for that command. +-- Response files are placed in a dedicated @rps@ directory under the build directory. This avoids +-- clutering the work tree or interfearing with other build directories. +responseFilePath :: FilePath -> Action FilePath +responseFilePath outputFilePath = do + buildDir <- buildRoot + return $ buildDir </> "rsp" </> outputFilePath -- | Link a file tracking the link target. Create the target directory if -- missing. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/ea8b402afb2cc37f46aa16d84e2dadb… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/ea8b402afb2cc37f46aa16d84e2dadb… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 4 commits: Avoid mkTick in Core Prep breaking ANF
by Marge Bot (＠marge-bot) 04 Jun '26

04 Jun '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: f9bcfac2 by sheaf at 2026-06-03T14:47:19-04:00 Avoid mkTick in Core Prep breaking ANF As discovered in #27182, mkTick can break ANF. This patch introduces a variant of mkTick that skips the single optimisation that could break ANF. This is preferrable over switching to the raw Tick constructor, as the latter may introduce spurious cost centres in profiling reports. This is a temporary measure until we more thoroughly refactor how mkTick works (see #27141). See Note [mkTick breaks ANF] in GHC.CoreToStg.Prep. Fixes #27182 - - - - - cf1fd661 by Artem Pelenitsyn at 2026-06-03T14:48:09-04:00 clarify comment for getSizeofMutableByteArray#: we get the size in bytes, not "elements" - - - - - 4b4aba00 by sheaf at 2026-06-04T07:54:22-04:00 Fix AArch64 clobbering bug for MUL2 On AArch64, the code generator could clobber one of the input operands when computing the lower bits of a MUL2 operation. This rendered invalid the subsequent computation of the high bits. This commit fixes that by using a temporary register. The register allocator can remove the redundant move in the common case when the registers do not conflict. Fixes #27046 - - - - - c19aa850 by Simon Jakobi at 2026-06-04T07:54:23-04:00 testsuite: Deduplicate --only test names config.only is assumed to be a set, but supplying --only overwrote it with the (list) argparse result, which can contain duplicates. When a test ran, config.only.remove(name) dropped only the first occurrence, so a duplicated name lingered and was later misreported as a "test not found" framework failure. Store it as a set instead. Fixes #27322 Co-Authored-By: Claude Opus 4.7 <noreply(a)anthropic.com> - - - - - 12 changed files: - + changelog.d/T27046 - + changelog.d/T27182.md - compiler/GHC/Builtin/primops.txt.pp - compiler/GHC/CmmToAsm/AArch64/CodeGen.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/CoreToStg/Prep.hs - testsuite/driver/runtests.py - + testsuite/tests/codeGen/should_run/T27046.hs - + testsuite/tests/codeGen/should_run/T27046_cmm.cmm - testsuite/tests/codeGen/should_run/all.T - + testsuite/tests/profiling/should_compile/T27182.hs - testsuite/tests/profiling/should_compile/all.T Changes: ===================================== changelog.d/T27046 ===================================== @@ -0,0 +1,9 @@ +section: compiler +issues: #27046 +mrs: !16031 +synopsis: + Avoid AArch64 register clobbering bug in MUL2 +description: + Fixes an issue in which, on AArch64, code generation for the MUL2 operation + could clobber one of the input operands when computing the lower bits, which + rendered invalid the subsequent computation of the high bits. ===================================== changelog.d/T27182.md ===================================== @@ -0,0 +1,8 @@ +section: compiler +issues: #27182 +mrs: !16003 +synopsis: + Fix `getStgArgFromTrivialArg` panic in CoreToStg +description: + Avoid a `getStgArgFromTrivialArg` panic in CoreToStg due to a call to `mkTick` + in Core Prep which invalidated ANF. ===================================== compiler/GHC/Builtin/primops.txt.pp ===================================== @@ -2149,7 +2149,7 @@ primop SizeofMutableByteArrayOp "sizeofMutableByteArray#" GenPrimOp primop GetSizeofMutableByteArrayOp "getSizeofMutableByteArray#" GenPrimOp MutableByteArray# s -> State# s -> (# State# s, Int# #) - {Return the number of elements in the array, correctly accounting for + {Return the number of bytes in the array, correctly accounting for the effect of 'shrinkMutableByteArray#' and 'resizeMutableByteArray#'. @since 0.5.0.0} ===================================== compiler/GHC/CmmToAsm/AArch64/CodeGen.hs ===================================== @@ -2300,11 +2300,19 @@ genCCall target dest_regs arg_regs = do let lo = getRegisterReg platform (CmmLocal dst_lo) hi = getRegisterReg platform (CmmLocal dst_hi) nd = getRegisterReg platform (CmmLocal dst_needed) + + -- Generate a fresh virtual register for the low word computation. + -- This avoids clobbering reg_a or reg_b in the first MUL instruction, + -- which could for example happen if 'lo' and 'reg_a' are the same + -- virtual register. + tmp_lo <- getNewRegNat II64 + return $ code_x `appOL` code_y `snocOL` - MUL II64 (OpReg W64 lo) (OpReg W64 reg_a) (OpReg W64 reg_b) `snocOL` + MUL II64 (OpReg W64 tmp_lo) (OpReg W64 reg_a) (OpReg W64 reg_b) `snocOL` SMULH (OpReg W64 hi) (OpReg W64 reg_a) (OpReg W64 reg_b) `snocOL` + MOV (OpReg W64 lo) (OpReg W64 tmp_lo) `snocOL` -- Are all high bits equal to the sign bit of the low word? -- nd = (hi == ASR(lo,width-1)) ? 1 : 0 CMP (OpReg W64 hi) (OpRegShift W64 lo SASR (widthInBits w - 1)) `snocOL` ===================================== compiler/GHC/Core/Utils.hs ===================================== @@ -11,6 +11,7 @@ module GHC.Core.Utils ( -- * Constructing expressions mkCast, mkCastMCo, mkPiMCo, mkTick, mkTicks, mkTickNoHNF, tickHNFArgs, + mkTickCpe, bindNonRec, needsCaseBinding, needsCaseBindingL, mkAltExpr, mkDefaultCase, mkSingleAltCase, @@ -319,7 +320,18 @@ mkCast expr co -- * Split profiling ticks into counting/scoping parts so that the two parts -- can be placed independently into the AST. mkTick :: CoreTickish -> CoreExpr -> CoreExpr -mkTick t orig_expr = mkTick' orig_expr +mkTick = mk_tick False + +-- | A version of 'mkTick' that preserves ANF, for use in Core Prep. +-- +-- See Note [mkTick breaks ANF] in GHC.CoreToStg.Prep. +mkTickCpe :: CoreTickish -> CoreExpr -> CoreExpr +mkTickCpe = mk_tick True + +-- | Internal function used to define both 'mkTick' and 'mkTickCpe' +-- without duplication. +mk_tick :: Bool -> CoreTickish -> CoreExpr -> CoreExpr +mk_tick preserve_anf t orig_expr = mkTick' orig_expr where -- Some ticks (cost-centres) can be split in two, with the -- non-counting part having laxer placement properties. @@ -343,7 +355,7 @@ mkTick t orig_expr = mkTick' orig_expr -- Push SCCs into lambdas. -- See (PSCC2) in Note [Pushing SCCs inwards]. | can_split - -> Tick (mkNoScope t) $ Lam x $ mkTick (mkNoCount t) e + -> Tick (mkNoScope t) $ Lam x $ mk_tick preserve_anf (mkNoCount t) e App f arg -- All ticks float inwards through non-runtime arguments, as per @@ -353,7 +365,9 @@ mkTick t orig_expr = mkTick' orig_expr -- Push SCCs into saturated constructor applications. -- See (PSCC3) in Note [Pushing SCCs inwards]. - | isSaturatedConApp expr + | not preserve_anf -- this optimisation breaks ANF; + -- see Note [mkTick breaks ANF] in GHC.CoreToStg.Prep + , isSaturatedConApp expr , tickishPlace t == PlaceCostCentre || can_split -> if tickishPlace t == PlaceCostCentre then tickHNFArgs t expr ===================================== compiler/GHC/CoreToStg/Prep.hs ===================================== @@ -801,7 +801,9 @@ cpeBodyF env (Tick tickish expr) ; return (FloatTick tickish `consFloat` floats, body) } | otherwise = do { body <- cpeBody env expr - ; return (emptyFloats, mkTick tickish' body) } + ; return (emptyFloats, mkTickCpe tickish' body) } + -- Use mkTickCpe and not mkTick, as the latter may break ANF (#27182). + -- See (TickANF2) in Note [mkTick breaks ANF]. where tickish' | Breakpoint ext bid fvs <- tickish -- See also 'substTickish' @@ -905,6 +907,28 @@ cpeBodyF env (Case scrut bndr ty alts) ; rhs' <- cpeBody env2 rhs ; return (Alt con bs' rhs') } +{- Note [mkTick breaks ANF] +~~~~~~~~~~~~~~~~~~~~~~~~~~~ +mkTick does not preserve the ANF property as required by Core Prep (see +Note [CorePrep invariants]), as seen in #27182. Given: + + mkTick scc<foo> (\ (eta :: Char -> Bool) -> BindP (p :: Int) eta) + +mkTick will push the SCC into the constructor application, resulting in: + + \ (eta :: Char -> Bool) -> BindP (p :: Int) (scc<oneM> eta) + +To avoid this problem (at least until 'mkTick' is more thoroughly reworked to +avoid this infelicity, see #27141), we define a variant of 'mkTick', called +'mkTickCpe', which does not push ticks into constructor applications (this is +the only optimisation done by 'mkTick' that can break ANF). + +We prefer using a small variant of 'mkTick' rather than using the 'Tick' +constructor, as the latter can slightly degrade profiling reports by failing to +combine ticks (can result in spurious cost centres with 0 entries appearing in +profiling reports). +-} + -- --------------------------------------------------------------------------- -- CpeBody: produces a result satisfying CpeBody -- --------------------------------------------------------------------------- @@ -1207,7 +1231,7 @@ cpeApp top_env expr rebuild_app' env (a : as) fun' floats ss rt_ticks req_depth = case a of -- See Note [Ticks and mandatory eta expansion] _ | not (null rt_ticks), req_depth <= 0 - -> let tick_fun = foldr mkTick fun' rt_ticks + -> let tick_fun = foldr mkTickCpe fun' rt_ticks in rebuild_app' env (a : as) tick_fun floats ss rt_ticks req_depth AIApp (Type arg_ty) @@ -2307,7 +2331,7 @@ wrapBinds floats body mk_bind (UnsafeEqualityCase scrut b con bs) body = mkSingleAltCase scrut b con bs body mk_bind (FloatTick tickish) body - = mkTick tickish body + = mkTickCpe tickish body -- | Put floats at top-level deFloatTop :: Floats -> [CoreBind] @@ -2735,7 +2759,7 @@ newVar env ty wrapTicks :: Floats -> CoreExpr -> (Floats, CoreExpr) wrapTicks floats expr | (floats1, ticks1) <- fold_fun go floats - = (floats1, foldrOL mkTick expr ticks1) + = (floats1, foldrOL mkTickCpe expr ticks1) where fold_fun f floats = let (binds, ticks) = foldlOL f (nilOL,nilOL) (fs_binds floats) in (floats { fs_binds = binds }, ticks) @@ -2755,8 +2779,8 @@ wrapTicks floats expr wrap t (Float bind bound info) = Float (wrapBind t bind) bound info wrap _ f = pprPanic "Unexpected FloatingBind" (ppr f) - wrapBind t (NonRec binder rhs) = NonRec binder (mkTick t rhs) - wrapBind t (Rec pairs) = Rec (mapSnd (mkTick t) pairs) + wrapBind t (NonRec binder rhs) = NonRec binder (mkTickCpe t rhs) + wrapBind t (Rec pairs) = Rec (mapSnd (mkTickCpe t) pairs) ------------------------------------------------------------------------------ -- Numeric literals ===================================== testsuite/driver/runtests.py ===================================== @@ -133,7 +133,7 @@ if args.unexpected_output_dir: config.unexpected_output_dir = Path(args.unexpected_output_dir) if args.only: - config.only = args.only + config.only = set(args.only) config.run_only_some_tests = True if args.skip: ===================================== testsuite/tests/codeGen/should_run/T27046.hs ===================================== @@ -0,0 +1,29 @@ +{-# LANGUAGE MagicHash #-} +{-# LANGUAGE ForeignFunctionInterface, GHCForeignImportPrim, UnliftedFFITypes #-} + +module Main where + +import Control.Monad + ( unless ) +import Data.Bits + ( shiftL ) +import GHC.Exts + ( Int64# ) +import GHC.Int + ( Int64(..) ) + +foreign import prim "test_mul2_clobber" + test_mul2_clobber :: Int64# -> Int64# -> Int64# + +main :: IO () +main = do + let + I64# x = 1 `shiftL` 32 + hi = I64# $ test_mul2_clobber x x + + unless ( hi == 1 ) $ + error $ unlines + [ "Incorrect result for Mul2 operation." + , "Expected high word: 1" + , " Actual high word: " ++ show hi + ] ===================================== testsuite/tests/codeGen/should_run/T27046_cmm.cmm ===================================== @@ -0,0 +1,13 @@ +#include "Cmm.h" + +// Test for #27046 +test_mul2_clobber (bits64 x, bits64 y) +{ + bits64 hi, nd; + + // Deliberately alias the destination 'lo' with the source 'x' + // This forces the NCG to use the same virtual register for both. + (nd, hi, x) = prim %mul2_64(x, y); + + return (hi); +} ===================================== testsuite/tests/codeGen/should_run/all.T ===================================== @@ -260,6 +260,7 @@ test('T25364', normal, compile_and_run, ['']) test('T26061', normal, compile_and_run, ['']) test('T26537', normal, compile_and_run, ['-O2 -fregs-graph']) test('T24016', normal, compile_and_run, ['-O1 -fPIC']) +test('T27046', [req_cmm], compile_and_run, ['T27046_cmm.cmm']) # Check that GHC-generated finalizers run on Darwin. The Apple linker doesn't # support --wrap, so we can't intercept hs_spt_remove directly. Instead we ===================================== testsuite/tests/profiling/should_compile/T27182.hs ===================================== @@ -0,0 +1,6 @@ +module T27182 ( oneM ) where + +data Parser = BindP Int ( Char -> Bool ) + +oneM :: Int -> ( Char -> Bool ) -> Parser +oneM p = BindP p ===================================== testsuite/tests/profiling/should_compile/all.T ===================================== @@ -22,3 +22,4 @@ test('T19894', [test_opts, extra_files(['T19894'])], multimod_compile, ['Main', test('T20938', [test_opts], compile, ['-O -prof']) test('T26056', [test_opts], compile, ['-O -prof']) test('T27121', [test_opts, extra_files(['T27121_aux.hs'])], multimod_compile, ['T27121', '-v0 -O -prof -fprof-auto']) +test('T27182', [test_opts], compile, ['-O -prof -fprof-late']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/bc8fcb441cbcafd214c80761db298b… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/bc8fcb441cbcafd214c80761db298b… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/davide/hadrian-windows-symlink] 3 commits: Avoid mkTick in Core Prep breaking ANF
by David Eichmann (＠DavidEichmann) 04 Jun '26

04 Jun '26

David Eichmann pushed to branch wip/davide/hadrian-windows-symlink at Glasgow Haskell Compiler / GHC Commits: f9bcfac2 by sheaf at 2026-06-03T14:47:19-04:00 Avoid mkTick in Core Prep breaking ANF As discovered in #27182, mkTick can break ANF. This patch introduces a variant of mkTick that skips the single optimisation that could break ANF. This is preferrable over switching to the raw Tick constructor, as the latter may introduce spurious cost centres in profiling reports. This is a temporary measure until we more thoroughly refactor how mkTick works (see #27141). See Note [mkTick breaks ANF] in GHC.CoreToStg.Prep. Fixes #27182 - - - - - cf1fd661 by Artem Pelenitsyn at 2026-06-03T14:48:09-04:00 clarify comment for getSizeofMutableByteArray#: we get the size in bytes, not "elements" - - - - - 7a23957d by David Eichmann at 2026-06-04T12:24:02+01:00 Hadrian: remove unused wrapper scripts from windows bindist These wrapper scripts are only installed on non-relocatable builds which are not generally supported on windows. - - - - - 7 changed files: - + changelog.d/T27182.md - compiler/GHC/Builtin/primops.txt.pp - compiler/GHC/Core/Utils.hs - compiler/GHC/CoreToStg/Prep.hs - hadrian/src/Rules/BinaryDist.hs - + testsuite/tests/profiling/should_compile/T27182.hs - testsuite/tests/profiling/should_compile/all.T Changes: ===================================== changelog.d/T27182.md ===================================== @@ -0,0 +1,8 @@ +section: compiler +issues: #27182 +mrs: !16003 +synopsis: + Fix `getStgArgFromTrivialArg` panic in CoreToStg +description: + Avoid a `getStgArgFromTrivialArg` panic in CoreToStg due to a call to `mkTick` + in Core Prep which invalidated ANF. ===================================== compiler/GHC/Builtin/primops.txt.pp ===================================== @@ -2149,7 +2149,7 @@ primop SizeofMutableByteArrayOp "sizeofMutableByteArray#" GenPrimOp primop GetSizeofMutableByteArrayOp "getSizeofMutableByteArray#" GenPrimOp MutableByteArray# s -> State# s -> (# State# s, Int# #) - {Return the number of elements in the array, correctly accounting for + {Return the number of bytes in the array, correctly accounting for the effect of 'shrinkMutableByteArray#' and 'resizeMutableByteArray#'. @since 0.5.0.0} ===================================== compiler/GHC/Core/Utils.hs ===================================== @@ -11,6 +11,7 @@ module GHC.Core.Utils ( -- * Constructing expressions mkCast, mkCastMCo, mkPiMCo, mkTick, mkTicks, mkTickNoHNF, tickHNFArgs, + mkTickCpe, bindNonRec, needsCaseBinding, needsCaseBindingL, mkAltExpr, mkDefaultCase, mkSingleAltCase, @@ -319,7 +320,18 @@ mkCast expr co -- * Split profiling ticks into counting/scoping parts so that the two parts -- can be placed independently into the AST. mkTick :: CoreTickish -> CoreExpr -> CoreExpr -mkTick t orig_expr = mkTick' orig_expr +mkTick = mk_tick False + +-- | A version of 'mkTick' that preserves ANF, for use in Core Prep. +-- +-- See Note [mkTick breaks ANF] in GHC.CoreToStg.Prep. +mkTickCpe :: CoreTickish -> CoreExpr -> CoreExpr +mkTickCpe = mk_tick True + +-- | Internal function used to define both 'mkTick' and 'mkTickCpe' +-- without duplication. +mk_tick :: Bool -> CoreTickish -> CoreExpr -> CoreExpr +mk_tick preserve_anf t orig_expr = mkTick' orig_expr where -- Some ticks (cost-centres) can be split in two, with the -- non-counting part having laxer placement properties. @@ -343,7 +355,7 @@ mkTick t orig_expr = mkTick' orig_expr -- Push SCCs into lambdas. -- See (PSCC2) in Note [Pushing SCCs inwards]. | can_split - -> Tick (mkNoScope t) $ Lam x $ mkTick (mkNoCount t) e + -> Tick (mkNoScope t) $ Lam x $ mk_tick preserve_anf (mkNoCount t) e App f arg -- All ticks float inwards through non-runtime arguments, as per @@ -353,7 +365,9 @@ mkTick t orig_expr = mkTick' orig_expr -- Push SCCs into saturated constructor applications. -- See (PSCC3) in Note [Pushing SCCs inwards]. - | isSaturatedConApp expr + | not preserve_anf -- this optimisation breaks ANF; + -- see Note [mkTick breaks ANF] in GHC.CoreToStg.Prep + , isSaturatedConApp expr , tickishPlace t == PlaceCostCentre || can_split -> if tickishPlace t == PlaceCostCentre then tickHNFArgs t expr ===================================== compiler/GHC/CoreToStg/Prep.hs ===================================== @@ -801,7 +801,9 @@ cpeBodyF env (Tick tickish expr) ; return (FloatTick tickish `consFloat` floats, body) } | otherwise = do { body <- cpeBody env expr - ; return (emptyFloats, mkTick tickish' body) } + ; return (emptyFloats, mkTickCpe tickish' body) } + -- Use mkTickCpe and not mkTick, as the latter may break ANF (#27182). + -- See (TickANF2) in Note [mkTick breaks ANF]. where tickish' | Breakpoint ext bid fvs <- tickish -- See also 'substTickish' @@ -905,6 +907,28 @@ cpeBodyF env (Case scrut bndr ty alts) ; rhs' <- cpeBody env2 rhs ; return (Alt con bs' rhs') } +{- Note [mkTick breaks ANF] +~~~~~~~~~~~~~~~~~~~~~~~~~~~ +mkTick does not preserve the ANF property as required by Core Prep (see +Note [CorePrep invariants]), as seen in #27182. Given: + + mkTick scc<foo> (\ (eta :: Char -> Bool) -> BindP (p :: Int) eta) + +mkTick will push the SCC into the constructor application, resulting in: + + \ (eta :: Char -> Bool) -> BindP (p :: Int) (scc<oneM> eta) + +To avoid this problem (at least until 'mkTick' is more thoroughly reworked to +avoid this infelicity, see #27141), we define a variant of 'mkTick', called +'mkTickCpe', which does not push ticks into constructor applications (this is +the only optimisation done by 'mkTick' that can break ANF). + +We prefer using a small variant of 'mkTick' rather than using the 'Tick' +constructor, as the latter can slightly degrade profiling reports by failing to +combine ticks (can result in spurious cost centres with 0 entries appearing in +profiling reports). +-} + -- --------------------------------------------------------------------------- -- CpeBody: produces a result satisfying CpeBody -- --------------------------------------------------------------------------- @@ -1207,7 +1231,7 @@ cpeApp top_env expr rebuild_app' env (a : as) fun' floats ss rt_ticks req_depth = case a of -- See Note [Ticks and mandatory eta expansion] _ | not (null rt_ticks), req_depth <= 0 - -> let tick_fun = foldr mkTick fun' rt_ticks + -> let tick_fun = foldr mkTickCpe fun' rt_ticks in rebuild_app' env (a : as) tick_fun floats ss rt_ticks req_depth AIApp (Type arg_ty) @@ -2307,7 +2331,7 @@ wrapBinds floats body mk_bind (UnsafeEqualityCase scrut b con bs) body = mkSingleAltCase scrut b con bs body mk_bind (FloatTick tickish) body - = mkTick tickish body + = mkTickCpe tickish body -- | Put floats at top-level deFloatTop :: Floats -> [CoreBind] @@ -2735,7 +2759,7 @@ newVar env ty wrapTicks :: Floats -> CoreExpr -> (Floats, CoreExpr) wrapTicks floats expr | (floats1, ticks1) <- fold_fun go floats - = (floats1, foldrOL mkTick expr ticks1) + = (floats1, foldrOL mkTickCpe expr ticks1) where fold_fun f floats = let (binds, ticks) = foldlOL f (nilOL,nilOL) (fs_binds floats) in (floats { fs_binds = binds }, ticks) @@ -2755,8 +2779,8 @@ wrapTicks floats expr wrap t (Float bind bound info) = Float (wrapBind t bind) bound info wrap _ f = pprPanic "Unexpected FloatingBind" (ppr f) - wrapBind t (NonRec binder rhs) = NonRec binder (mkTick t rhs) - wrapBind t (Rec pairs) = Rec (mapSnd (mkTick t) pairs) + wrapBind t (NonRec binder rhs) = NonRec binder (mkTickCpe t rhs) + wrapBind t (Rec pairs) = Rec (mapSnd (mkTickCpe t) pairs) ------------------------------------------------------------------------------ -- Numeric literals ===================================== hadrian/src/Rules/BinaryDist.hs ===================================== @@ -289,23 +289,25 @@ bindistRules = do copyFile ("hadrian" -/- "cfg" -/- "default.target.in") (bindistFilesDir -/- "default.target.in") copyFile ("hadrian" -/- "cfg" -/- "default.host.target.in") (bindistFilesDir -/- "default.host.target.in") - -- todo: do we need these wrappers on windows - forM_ bin_targets $ \(pkg, _) -> do - needed_wrappers <- pkgToWrappers pkg - forM_ needed_wrappers $ \wrapper_name -> do - let suffix = if useGhcPrefix pkg - then "ghc-" ++ version - else version - wrapper_content <- wrapper wrapper_name - let unversioned_wrapper_path = bindistFilesDir -/- "wrappers" -/- wrapper_name - versioned_wrapper = wrapper_name ++ "-" ++ suffix - versioned_wrapper_path = bindistFilesDir -/- "wrappers" -/- versioned_wrapper - -- Write the wrapper to the versioned path - writeFile' versioned_wrapper_path wrapper_content - -- Create a symlink from the non-versioned to the versioned. - liftIO $ do - IO.removeFile unversioned_wrapper_path <|> return () - IO.createFileLink versioned_wrapper unversioned_wrapper_path + -- These wrapper scripts are only necessary in the configure/install + -- workflow which is not supported on windows. + unless windowsHost $ do + forM_ bin_targets $ \(pkg, _) -> do + needed_wrappers <- pkgToWrappers pkg + forM_ needed_wrappers $ \wrapper_name -> do + let suffix = if useGhcPrefix pkg + then "ghc-" ++ version + else version + wrapper_content <- wrapper wrapper_name + let unversioned_wrapper_path = bindistFilesDir -/- "wrappers" -/- wrapper_name + versioned_wrapper = wrapper_name ++ "-" ++ suffix + versioned_wrapper_path = bindistFilesDir -/- "wrappers" -/- versioned_wrapper + -- Write the wrapper to the versioned path + writeFile' versioned_wrapper_path wrapper_content + -- Create a symlink from the non-versioned to the versioned. + liftIO $ do + IO.removeFile unversioned_wrapper_path <|> return () + IO.createFileLink versioned_wrapper unversioned_wrapper_path let buildBinDist compressor = do win_target <- isWinTarget ===================================== testsuite/tests/profiling/should_compile/T27182.hs ===================================== @@ -0,0 +1,6 @@ +module T27182 ( oneM ) where + +data Parser = BindP Int ( Char -> Bool ) + +oneM :: Int -> ( Char -> Bool ) -> Parser +oneM p = BindP p ===================================== testsuite/tests/profiling/should_compile/all.T ===================================== @@ -22,3 +22,4 @@ test('T19894', [test_opts, extra_files(['T19894'])], multimod_compile, ['Main', test('T20938', [test_opts], compile, ['-O -prof']) test('T26056', [test_opts], compile, ['-O -prof']) test('T27121', [test_opts, extra_files(['T27121_aux.hs'])], multimod_compile, ['T27121', '-v0 -O -prof -fprof-auto']) +test('T27182', [test_opts], compile, ['-O -prof -fprof-late']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/4f8b0e0d3471d1f592ce66007c7b2f… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/4f8b0e0d3471d1f592ce66007c7b2f… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/o0-fmax-simplifier-iterations-2] compiler: set -fmax-simplifier-iterations=2 for -O0
by Cheng Shao (＠TerrorJack) 04 Jun '26

04 Jun '26

Cheng Shao pushed to branch wip/o0-fmax-simplifier-iterations-2 at Glasgow Haskell Compiler / GHC Commits: 501b314d by Cheng Shao at 2026-06-04T11:07:11+00:00 compiler: set -fmax-simplifier-iterations=2 for -O0 This patch sets `-fmax-simplifier-iterations=2` as the new default under `-O0` for faster compilation of unoptimized code. See added note for details. Closes #27326. Co-authored-by: Codex <codex(a)openai.com> - - - - - 4 changed files: - + changelog.d/ghc-o0-fmax-simplifier-iterations-2 - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Driver/Session.hs - docs/users_guide/using-optimisation.rst Changes: ===================================== changelog.d/ghc-o0-fmax-simplifier-iterations-2 ===================================== @@ -0,0 +1,13 @@ +section: compiler +synopsis: Set ``-fmax-simplifier-iterations=2`` for ``-O0`` +issues: #27326 +mrs: !16137 + +description: { + The maximum number of simplifier iterations + (``-fmax-simplifier-iterations``) is now tied to the optimisation + level: at most 2 iterations at ``-O0`` (previously 4) and still 4 at + ``-O1``/``-O2``. This speeds up unoptimised compilation. An explicit + ``-fmax-simplifier-iterations=⟨n⟩`` still overrides the default, as + long as it appears after the ``-O`` flag on the command line. +} ===================================== compiler/GHC/Driver/DynFlags.hs ===================================== @@ -576,7 +576,8 @@ defaultDynFlags mySettings = verbosity = 0, debugLevel = 0, simplPhases = 2, - maxSimplIterations = 4, + maxSimplIterations = 2, -- The -O0 default. 'updOptLevel' raises this to 4 at -O1/-O2. See + -- Note [Simplifier iterations and the optimisation level]. ruleCheck = Nothing, binBlobThreshold = Just 500000, -- 500K is a good default (see #16190) maxRelevantBinds = Just 6, ===================================== compiler/GHC/Driver/Session.hs ===================================== @@ -786,15 +786,45 @@ setInteractivePrint f d = d { interactivePrint = Just f} ----------------------------------------------------------------------------- -- Setting the optimisation level +{- Note [Simplifier iterations and the optimisation level] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +At -O0 the only Core-to-Core pass that runs is the final simplifier pass (see +'GHC.Core.Opt.Pipeline.getCoreToDo'); every optimisation-specific pass is gated +off. We therefore want as few simplifier iterations as possible at -O0, since +the later iterations only chase optimisation opportunities the user opted out of +by choosing -O0. + +We cannot drop to a *single* iteration, though. The final simplifier pass is +still load-bearing for correctness: a single iteration can leave a recursive +superclass dictionary with an unreduced superclass selector applied to it, which +then builds an infinite dictionary tower and diverges (<<loop>> at -O, OOM at +-O0). See #21973 and test T21973b. The fix needs (at least) two iterations: the +first inlines the dictionary functions to expose a constructor, and the second +reduces the superclass selector against it, making the recursive dictionary +dead. Empirically two iterations suffice across the known reproducers; the +simplifier offers no proof of a fixed bound, so we keep a small margin rather +than the bare minimum. + +So we tie 'maxSimplIterations' to the optimisation level: 2 iterations at -O0 +and 4 at -O1/-O2. This is a noticeable win for unoptimised compilation, and most +noticeable for the byte-code interpreter (GHCi), which defaults to -O0 and codegen +does less work compared to other backends. + +An explicit -fmax-simplifier-iterations=⟨n⟩ still overrides this, as long as it +appears after the -O flag on the command line (the usual flag-ordering rule for +options that -O adjusts). +-} + updOptLevelChanged :: Int -> DynFlags -> (DynFlags, Bool) -- ^ Sets the 'DynFlags' to be appropriate to the optimisation level and signals if any changes took place updOptLevelChanged n dfs - = (dfs3, changed1 || changed2 || changed3) + = (dfs4, changed1 || changed2 || changed3 || changed4) where final_n = max 0 (min 2 n) -- Clamp to 0 <= n <= 2 (dfs1, changed1) = foldr unset (dfs , False) remove_gopts (dfs2, changed2) = foldr set (dfs1, False) extra_gopts (dfs3, changed3) = setLlvmOptLevel dfs2 + (dfs4, changed4) = setSimplIterations dfs3 extra_gopts = [ f | (ns,f) <- optLevelFlags, final_n `elem` ns ] remove_gopts = [ f | (ns,f) <- optLevelFlags, final_n `notElem` ns ] @@ -814,6 +844,14 @@ updOptLevelChanged n dfs | llvmOptLevel dfs /= llvm_n = (dfs{ llvmOptLevel = llvm_n }, True) | otherwise = (dfs, False) + -- See Note [Simplifier iterations and the optimisation level] + simpl_iters = if final_n == 0 then 2 else 4 + + setSimplIterations dfs + | maxSimplIterations dfs /= simpl_iters = + (dfs{ maxSimplIterations = simpl_iters }, True) + | otherwise = (dfs, False) + updOptLevel :: Int -> DynFlags -> DynFlags -- ^ Sets the 'DynFlags' to be appropriate to the optimisation level updOptLevel n = fst . updOptLevelChanged n ===================================== docs/users_guide/using-optimisation.rst ===================================== @@ -914,11 +914,12 @@ as such you shouldn't need to set any of them explicitly. A flag :ghc-flag:`-Wincomplete-patterns` and :ghc-flag:`-Wincomplete-uni-patterns`. .. ghc-flag:: -fmax-simplifier-iterations=⟨n⟩ - :shortdesc: *default: 4.* Set the max iterations for the simplifier. + :shortdesc: *default: 2 at :ghc-flag:`-O0`, 4 otherwise.* Set the max iterations + for the simplifier. :type: dynamic :category: - :default: 4 + :default: 2 at :ghc-flag:`-O0`, 4 at :ghc-flag:`-O1` and :ghc-flag:`-O2` Sets the maximal number of iterations for the simplifier. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/501b314da11288285b8ff70b3f6954a… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/501b314da11288285b8ff70b3f6954a… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/o0-fmax-simplifier-iterations-2] compiler: set -fmax-simplifier-iterations=2 for -O0
by Cheng Shao (＠TerrorJack) 04 Jun '26

04 Jun '26

Cheng Shao pushed to branch wip/o0-fmax-simplifier-iterations-2 at Glasgow Haskell Compiler / GHC Commits: 64b268d1 by Cheng Shao at 2026-06-04T11:02:37+00:00 compiler: set -fmax-simplifier-iterations=2 for -O0 This patch sets `-fmax-simplifier-iterations=2` as the new default under `-O0` for faster compilation of unoptimized code. See added note for details. Closes #27326. Co-authored-by: Codex <codex(a)openai.com> - - - - - 4 changed files: - + changelog.d/ghc-o0-fmax-simplifier-iterations-2 - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Driver/Session.hs - docs/users_guide/using-optimisation.rst Changes: ===================================== changelog.d/ghc-o0-fmax-simplifier-iterations-2 ===================================== @@ -0,0 +1,13 @@ +section: compiler +synopsis: Set ``-fmax-simplifier-iterations=2`` for ``-O0`` +issues: #27326 +mrs: !16136 + +description: { + The maximum number of simplifier iterations + (``-fmax-simplifier-iterations``) is now tied to the optimisation + level: at most 2 iterations at ``-O0`` (previously 4) and still 4 at + ``-O1``/``-O2``. This speeds up unoptimised compilation. An explicit + ``-fmax-simplifier-iterations=⟨n⟩`` still overrides the default, as + long as it appears after the ``-O`` flag on the command line. +} ===================================== compiler/GHC/Driver/DynFlags.hs ===================================== @@ -576,7 +576,8 @@ defaultDynFlags mySettings = verbosity = 0, debugLevel = 0, simplPhases = 2, - maxSimplIterations = 4, + maxSimplIterations = 2, -- The -O0 default. 'updOptLevel' raises this to 4 at -O1/-O2. See + -- Note [Simplifier iterations and the optimisation level]. ruleCheck = Nothing, binBlobThreshold = Just 500000, -- 500K is a good default (see #16190) maxRelevantBinds = Just 6, ===================================== compiler/GHC/Driver/Session.hs ===================================== @@ -786,15 +786,45 @@ setInteractivePrint f d = d { interactivePrint = Just f} ----------------------------------------------------------------------------- -- Setting the optimisation level +{- Note [Simplifier iterations and the optimisation level] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +At -O0 the only Core-to-Core pass that runs is the final simplifier pass (see +'GHC.Core.Opt.Pipeline.getCoreToDo'); every optimisation-specific pass is gated +off. We therefore want as few simplifier iterations as possible at -O0, since +the later iterations only chase optimisation opportunities the user opted out of +by choosing -O0. + +We cannot drop to a *single* iteration, though. The final simplifier pass is +still load-bearing for correctness: a single iteration can leave a recursive +superclass dictionary with an unreduced superclass selector applied to it, which +then builds an infinite dictionary tower and diverges (<<loop>> at -O, OOM at +-O0). See #21973 and test T21973b. The fix needs (at least) two iterations: the +first inlines the dictionary functions to expose a constructor, and the second +reduces the superclass selector against it, making the recursive dictionary +dead. Empirically two iterations suffice across the known reproducers; the +simplifier offers no proof of a fixed bound, so we keep a small margin rather +than the bare minimum. + +So we tie 'maxSimplIterations' to the optimisation level: 2 iterations at -O0 +and 4 at -O1/-O2. This is a noticeable win for unoptimised compilation, and most +noticeable for the byte-code interpreter (GHCi), which defaults to -O0 and codegen +does less work compared to other backends. + +An explicit -fmax-simplifier-iterations=⟨n⟩ still overrides this, as long as it +appears after the -O flag on the command line (the usual flag-ordering rule for +options that -O adjusts). +-} + updOptLevelChanged :: Int -> DynFlags -> (DynFlags, Bool) -- ^ Sets the 'DynFlags' to be appropriate to the optimisation level and signals if any changes took place updOptLevelChanged n dfs - = (dfs3, changed1 || changed2 || changed3) + = (dfs4, changed1 || changed2 || changed3 || changed4) where final_n = max 0 (min 2 n) -- Clamp to 0 <= n <= 2 (dfs1, changed1) = foldr unset (dfs , False) remove_gopts (dfs2, changed2) = foldr set (dfs1, False) extra_gopts (dfs3, changed3) = setLlvmOptLevel dfs2 + (dfs4, changed4) = setSimplIterations dfs3 extra_gopts = [ f | (ns,f) <- optLevelFlags, final_n `elem` ns ] remove_gopts = [ f | (ns,f) <- optLevelFlags, final_n `notElem` ns ] @@ -814,6 +844,14 @@ updOptLevelChanged n dfs | llvmOptLevel dfs /= llvm_n = (dfs{ llvmOptLevel = llvm_n }, True) | otherwise = (dfs, False) + -- See Note [Simplifier iterations and the optimisation level] + simpl_iters = if final_n == 0 then 2 else 4 + + setSimplIterations dfs + | maxSimplIterations dfs /= simpl_iters = + (dfs{ maxSimplIterations = simpl_iters }, True) + | otherwise = (dfs, False) + updOptLevel :: Int -> DynFlags -> DynFlags -- ^ Sets the 'DynFlags' to be appropriate to the optimisation level updOptLevel n = fst . updOptLevelChanged n ===================================== docs/users_guide/using-optimisation.rst ===================================== @@ -914,11 +914,12 @@ as such you shouldn't need to set any of them explicitly. A flag :ghc-flag:`-Wincomplete-patterns` and :ghc-flag:`-Wincomplete-uni-patterns`. .. ghc-flag:: -fmax-simplifier-iterations=⟨n⟩ - :shortdesc: *default: 4.* Set the max iterations for the simplifier. + :shortdesc: *default: 2 at :ghc-flag:`-O0`, 4 otherwise.* Set the max iterations + for the simplifier. :type: dynamic :category: - :default: 4 + :default: 2 at :ghc-flag:`-O0`, 4 at :ghc-flag:`-O1` and :ghc-flag:`-O2` Sets the maximal number of iterations for the simplifier. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/64b268d1c71bcba12d1cd47d90ec112… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/64b268d1c71bcba12d1cd47d90ec112… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/o0-fmax-simplifier-iterations-2] compiler: set -fmax-simplifier-iterations=2 for -O0
by Cheng Shao (＠TerrorJack) 04 Jun '26

04 Jun '26

Cheng Shao pushed to branch wip/o0-fmax-simplifier-iterations-2 at Glasgow Haskell Compiler / GHC Commits: 0dacd039 by Cheng Shao at 2026-06-04T11:01:34+00:00 compiler: set -fmax-simplifier-iterations=2 for -O0 This patch sets `-fmax-simplifier-iterations=2` as the new default under `-O0` for faster compilation of unoptimized code. See added note for details. Closes #27326. - - - - - 4 changed files: - + changelog.d/ghc-o0-fmax-simplifier-iterations-2 - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Driver/Session.hs - docs/users_guide/using-optimisation.rst Changes: ===================================== changelog.d/ghc-o0-fmax-simplifier-iterations-2 ===================================== @@ -0,0 +1,13 @@ +section: compiler +synopsis: Set ``-fmax-simplifier-iterations=2`` for ``-O0`` +issues: #27326 +mrs: !16136 + +description: { + The maximum number of simplifier iterations + (``-fmax-simplifier-iterations``) is now tied to the optimisation + level: at most 2 iterations at ``-O0`` (previously 4) and still 4 at + ``-O1``/``-O2``. This speeds up unoptimised compilation. An explicit + ``-fmax-simplifier-iterations=⟨n⟩`` still overrides the default, as + long as it appears after the ``-O`` flag on the command line. +} ===================================== compiler/GHC/Driver/DynFlags.hs ===================================== @@ -576,7 +576,8 @@ defaultDynFlags mySettings = verbosity = 0, debugLevel = 0, simplPhases = 2, - maxSimplIterations = 4, + maxSimplIterations = 2, -- The -O0 default. 'updOptLevel' raises this to 4 at -O1/-O2. See + -- Note [Simplifier iterations and the optimisation level]. ruleCheck = Nothing, binBlobThreshold = Just 500000, -- 500K is a good default (see #16190) maxRelevantBinds = Just 6, ===================================== compiler/GHC/Driver/Session.hs ===================================== @@ -786,15 +786,45 @@ setInteractivePrint f d = d { interactivePrint = Just f} ----------------------------------------------------------------------------- -- Setting the optimisation level +{- Note [Simplifier iterations and the optimisation level] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +At -O0 the only Core-to-Core pass that runs is the final simplifier pass (see +'GHC.Core.Opt.Pipeline.getCoreToDo'); every optimisation-specific pass is gated +off. We therefore want as few simplifier iterations as possible at -O0, since +the later iterations only chase optimisation opportunities the user opted out of +by choosing -O0. + +We cannot drop to a *single* iteration, though. The final simplifier pass is +still load-bearing for correctness: a single iteration can leave a recursive +superclass dictionary with an unreduced superclass selector applied to it, which +then builds an infinite dictionary tower and diverges (<<loop>> at -O, OOM at +-O0). See #21973 and test T21973b. The fix needs (at least) two iterations: the +first inlines the dictionary functions to expose a constructor, and the second +reduces the superclass selector against it, making the recursive dictionary +dead. Empirically two iterations suffice across the known reproducers; the +simplifier offers no proof of a fixed bound, so we keep a small margin rather +than the bare minimum. + +So we tie 'maxSimplIterations' to the optimisation level: 2 iterations at -O0 +and 4 at -O1/-O2. This is a noticeable win for unoptimised compilation, and most +noticeable for the byte-code interpreter (GHCi), which defaults to -O0 and codegen +does less work compared to other backends. + +An explicit -fmax-simplifier-iterations=⟨n⟩ still overrides this, as long as it +appears after the -O flag on the command line (the usual flag-ordering rule for +options that -O adjusts). +-} + updOptLevelChanged :: Int -> DynFlags -> (DynFlags, Bool) -- ^ Sets the 'DynFlags' to be appropriate to the optimisation level and signals if any changes took place updOptLevelChanged n dfs - = (dfs3, changed1 || changed2 || changed3) + = (dfs4, changed1 || changed2 || changed3 || changed4) where final_n = max 0 (min 2 n) -- Clamp to 0 <= n <= 2 (dfs1, changed1) = foldr unset (dfs , False) remove_gopts (dfs2, changed2) = foldr set (dfs1, False) extra_gopts (dfs3, changed3) = setLlvmOptLevel dfs2 + (dfs4, changed4) = setSimplIterations dfs3 extra_gopts = [ f | (ns,f) <- optLevelFlags, final_n `elem` ns ] remove_gopts = [ f | (ns,f) <- optLevelFlags, final_n `notElem` ns ] @@ -814,6 +844,14 @@ updOptLevelChanged n dfs | llvmOptLevel dfs /= llvm_n = (dfs{ llvmOptLevel = llvm_n }, True) | otherwise = (dfs, False) + -- See Note [Simplifier iterations and the optimisation level] + simpl_iters = if final_n == 0 then 2 else 4 + + setSimplIterations dfs + | maxSimplIterations dfs /= simpl_iters = + (dfs{ maxSimplIterations = simpl_iters }, True) + | otherwise = (dfs, False) + updOptLevel :: Int -> DynFlags -> DynFlags -- ^ Sets the 'DynFlags' to be appropriate to the optimisation level updOptLevel n = fst . updOptLevelChanged n ===================================== docs/users_guide/using-optimisation.rst ===================================== @@ -914,11 +914,12 @@ as such you shouldn't need to set any of them explicitly. A flag :ghc-flag:`-Wincomplete-patterns` and :ghc-flag:`-Wincomplete-uni-patterns`. .. ghc-flag:: -fmax-simplifier-iterations=⟨n⟩ - :shortdesc: *default: 4.* Set the max iterations for the simplifier. + :shortdesc: *default: 2 at :ghc-flag:`-O0`, 4 otherwise.* Set the max iterations + for the simplifier. :type: dynamic :category: - :default: 4 + :default: 2 at :ghc-flag:`-O0`, 4 at :ghc-flag:`-O1` and :ghc-flag:`-O2` Sets the maximal number of iterations for the simplifier. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/0dacd03911ce1e8dd38771797e7b56b… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/0dacd03911ce1e8dd38771797e7b56b… You're receiving this email because of your account on gitlab.haskell.org.

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