Cheng Shao pushed to branch wip/fix-clang64-split-sections at Glasgow Haskell Compiler / GHC
Commits:
6213bb57 by maralorn at 2026-01-02T16:30:32+01:00
GHC.Internal.Exception.Context: Fix comment
on addExceptionAnnotation
- - - - -
b820ff50 by Janis Voigtlaender at 2026-01-05T02:43:18-05:00
GHC.Internal.Control.Monad.replicateM: Fix comment
- - - - -
f9bda57b by Cheng Shao at 2026-01-05T09:25:50+01:00
compiler: change sectionProtection to take SectionType argument
This commit changes `sectionProtection` to only take `SectionType`
argument instead of whole `Section`, since it doesn't need the Cmm
section content anyway, and it can then be called in parts of NCG
where we only have a `SectionType` in scope.
- - - - -
9f426e30 by Cheng Shao at 2026-01-05T10:33:30+01:00
compiler: change isInitOrFiniSection to take SectionType argument
This commit changes `isInitOrFiniSection` to only take `SectionType`
argument instead of whole `Section`, since it doesn't need the Cmm
section content anyway, and it can then be called in parts of NCG
where we only have a `SectionType` in scope. Also marks it as
exported.
- - - - -
043299ef by Cheng Shao at 2026-01-05T10:42:34+01:00
compiler: fix split sections on windows
This patch fixes split sections on windows by emitting the right
COMDAT section header in NCG, see added comment for more explanation.
Fix #26696 #26494.
Co-authored-by: Codex
- - - - -
8 changed files:
- compiler/GHC/Cmm.hs
- compiler/GHC/Cmm/InitFini.hs
- compiler/GHC/CmmToAsm/Ppr.hs
- compiler/GHC/CmmToAsm/Wasm/FromCmm.hs
- compiler/GHC/CmmToC.hs
- compiler/GHC/CmmToLlvm/Data.hs
- libraries/ghc-internal/src/GHC/Internal/Control/Monad.hs
- libraries/ghc-internal/src/GHC/Internal/Exception/Context.hs
Changes:
=====================================
compiler/GHC/Cmm.hs
=====================================
@@ -278,8 +278,8 @@ data SectionProtection
deriving (Eq)
-- | Should a data in this section be considered constant at runtime
-sectionProtection :: Section -> SectionProtection
-sectionProtection (Section t _) = case t of
+sectionProtection :: SectionType -> SectionProtection
+sectionProtection t = case t of
Text -> ReadOnlySection
ReadOnlyData -> ReadOnlySection
RelocatableReadOnlyData -> WriteProtectedSection
=====================================
compiler/GHC/Cmm/InitFini.hs
=====================================
@@ -2,6 +2,7 @@
module GHC.Cmm.InitFini
( InitOrFini(..)
, isInitOrFiniArray
+ , isInitOrFiniSection
) where
import GHC.Prelude
@@ -63,8 +64,8 @@ finalizer CmmDecl will be emitted per module.
data InitOrFini = IsInitArray | IsFiniArray
isInitOrFiniArray :: RawCmmDecl -> Maybe (InitOrFini, [CLabel])
-isInitOrFiniArray (CmmData sect (CmmStaticsRaw _ lits))
- | Just initOrFini <- isInitOrFiniSection sect
+isInitOrFiniArray (CmmData (Section t _) (CmmStaticsRaw _ lits))
+ | Just initOrFini <- isInitOrFiniSection t
= Just (initOrFini, map get_label lits)
where
get_label :: CmmStatic -> CLabel
@@ -72,7 +73,7 @@ isInitOrFiniArray (CmmData sect (CmmStaticsRaw _ lits))
get_label static = pprPanic "isInitOrFiniArray: invalid entry" (ppr static)
isInitOrFiniArray _ = Nothing
-isInitOrFiniSection :: Section -> Maybe InitOrFini
-isInitOrFiniSection (Section InitArray _) = Just IsInitArray
-isInitOrFiniSection (Section FiniArray _) = Just IsFiniArray
+isInitOrFiniSection :: SectionType -> Maybe InitOrFini
+isInitOrFiniSection InitArray = Just IsInitArray
+isInitOrFiniSection FiniArray = Just IsFiniArray
isInitOrFiniSection _ = Nothing
=====================================
compiler/GHC/CmmToAsm/Ppr.hs
=====================================
@@ -1,4 +1,5 @@
{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE MultiWayIf #-}
-----------------------------------------------------------------------------
--
@@ -23,6 +24,7 @@ import GHC.Prelude
import GHC.Utils.Asm
import GHC.Cmm.CLabel
+import GHC.Cmm.InitFini
import GHC.Cmm
import GHC.CmmToAsm.Config
import GHC.Utils.Outputable as SDoc
@@ -240,21 +242,45 @@ pprGNUSectionHeader config t suffix =
| OSMinGW32 <- platformOS platform
-> text ".rdata"
| otherwise -> text ".ipe"
- flags = case t of
- Text
- | OSMinGW32 <- platformOS platform, splitSections
- -> text ",\"xr\""
- | splitSections
- -> text ",\"ax\"," <> sectionType platform "progbits"
- CString
- | OSMinGW32 <- platformOS platform
- -> empty
- | otherwise -> text ",\"aMS\"," <> sectionType platform "progbits" <> text ",1"
- IPE
- | OSMinGW32 <- platformOS platform
- -> empty
- | otherwise -> text ",\"a\"," <> sectionType platform "progbits"
- _ -> empty
+ flags
+ -- See
+ -- https://github.com/llvm/llvm-project/blob/llvmorg-21.1.8/lld/COFF/Chunks.cpp...
+ -- and https://llvm.org/docs/Extensions.html#section-directive.
+ -- LLD COFF backend gc-sections only work on COMDAT sections so
+ -- we need to mark it as a COMDAT section. You can use clang64
+ -- toolchain to compile small examples with
+ -- `-ffunction-sections -fdata-sections -S` to see these section
+ -- headers in the wild.
+ | OSMinGW32 <- platformOS platform,
+ splitSections =
+ if
+ | Just _ <- isInitOrFiniSection t -> text ",\"dw\""
+ | otherwise ->
+ let coff_section_flags
+ | Text <- t = "xr"
+ | UninitialisedData <- t = "bw"
+ | ReadWriteSection <- sectionProtection t = "dw"
+ | otherwise = "dr"
+ in hcat
+ [ text ",\"",
+ text coff_section_flags,
+ text "\",one_only,",
+ pprAsmLabel platform suffix
+ ]
+ | otherwise =
+ case t of
+ Text
+ | splitSections
+ -> text ",\"ax\"," <> sectionType platform "progbits"
+ CString
+ | OSMinGW32 <- platformOS platform
+ -> empty
+ | otherwise -> text ",\"aMS\"," <> sectionType platform "progbits" <> text ",1"
+ IPE
+ | OSMinGW32 <- platformOS platform
+ -> empty
+ | otherwise -> text ",\"a\"," <> sectionType platform "progbits"
+ _ -> empty
{-# SPECIALIZE pprGNUSectionHeader :: NCGConfig -> SectionType -> CLabel -> SDoc #-}
{-# SPECIALIZE pprGNUSectionHeader :: NCGConfig -> SectionType -> CLabel -> HLine #-} -- see Note [SPECIALIZE to HDoc] in GHC.Utils.Outputable
=====================================
compiler/GHC/CmmToAsm/Wasm/FromCmm.hs
=====================================
@@ -107,7 +107,7 @@ symKindFromCLabel lbl
-- | Calculate a data section's kind, see haddock docs of
-- 'DataSectionKind' for more explanation.
dataSectionKindFromCmmSection :: Section -> DataSectionKind
-dataSectionKindFromCmmSection s = case sectionProtection s of
+dataSectionKindFromCmmSection (Section t _) = case sectionProtection t of
ReadWriteSection -> SectionData
_ -> SectionROData
=====================================
compiler/GHC/CmmToC.hs
=====================================
@@ -121,7 +121,7 @@ pprTop platform = \case
pprDataExterns platform lits $$
pprWordArray platform (isSecConstant section) lbl lits
where
- isSecConstant section = case sectionProtection section of
+ isSecConstant (Section t _) = case sectionProtection t of
ReadOnlySection -> True
WriteProtectedSection -> True
_ -> False
=====================================
compiler/GHC/CmmToLlvm/Data.hs
=====================================
@@ -75,7 +75,7 @@ genLlvmData (sect, statics)
IsFiniArray -> fsLit "llvm.global_dtors"
in genGlobalLabelArray var clbls
-genLlvmData (sec, CmmStaticsRaw lbl xs) = do
+genLlvmData (sec@(Section t _), CmmStaticsRaw lbl xs) = do
label <- strCLabel_llvm lbl
static <- mapM genData xs
lmsec <- llvmSection sec
@@ -92,7 +92,7 @@ genLlvmData (sec, CmmStaticsRaw lbl xs) = do
then Just 2 else Just 1
Section Data _ -> Just $ platformWordSizeInBytes platform
_ -> Nothing
- const = if sectionProtection sec == ReadOnlySection
+ const = if sectionProtection t == ReadOnlySection
then Constant else Global
varDef = LMGlobalVar label tyAlias link lmsec align const
globDef = LMGlobal varDef struct
=====================================
libraries/ghc-internal/src/GHC/Internal/Control/Monad.hs
=====================================
@@ -314,7 +314,7 @@ Core: https://gitlab.haskell.org/ghc/ghc/issues/11795#note_118976
-- | @'replicateM' n act@ performs the action @act@ @n@ times,
-- and then returns the list of results.
--
--- @replicateM n (pure x) == 'replicate' n x@
+-- @replicateM n (pure x) == pure ('replicate' n x)@
--
-- ==== __Examples__
--
=====================================
libraries/ghc-internal/src/GHC/Internal/Exception/Context.hs
=====================================
@@ -64,7 +64,7 @@ instance Monoid ExceptionContext where
emptyExceptionContext :: ExceptionContext
emptyExceptionContext = ExceptionContext []
--- | Construct a singleton 'ExceptionContext' from an 'ExceptionAnnotation'.
+-- | Add an 'ExceptionAnnotation' to a given 'ExceptionContext'.
--
-- @since base-4.20.0.0
addExceptionAnnotation :: ExceptionAnnotation a => a -> ExceptionContext -> ExceptionContext
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/dc022bcb1aba9a5d67adaca8f0af24f...
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/dc022bcb1aba9a5d67adaca8f0af24f...
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