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Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC

Commits:

448a55aa
by maralorn at 2025-06-11T12:05:50-04:00
```
Add necessary flag for js linking
```

459e8a42

by maralorn at 2025-06-11T12:05:50-04:00

Don’t use additional linker flags to detect presence of -fno-pie in configure.ac

This mirrors the behavior of ghc-toolchain

4c4c33d1

by Krzysztof Gogolewski at 2025-06-11T12:05:51-04:00

Fix EPT enforcement when mixing unboxed tuples and non-tuples

The code was assuming that an alternative cannot be returning a normal
datacon and an unboxed tuple at the same time. However, as seen in #26107,
this can happen when using a GADT to refine the representation type.

The solution is just to conservatively return TagDunno.

6 changed files:

compiler/GHC/Stg/EnforceEpt/Types.hs
m4/fp_gcc_supports_no_pie.m4
m4/fptools_set_c_ld_flags.m4
+ testsuite/tests/rep-poly/T26107.hs
testsuite/tests/rep-poly/all.T
utils/ghc-toolchain/src/GHC/Toolchain/Tools/Link.hs

Changes:

compiler/GHC/Stg/EnforceEpt/Types.hs

@@ -39,8 +39,8 @@ type InferStgAlt        = GenStgAlt        'InferTaggedBinders
  combineAltInfo :: TagInfo -> TagInfo -> TagInfo
  combineAltInfo TagDunno         _              = TagDunno
  combineAltInfo _                TagDunno       = TagDunno
 -combineAltInfo (TagTuple {})    TagProper      = panic "Combining unboxed tuple with non-tuple result"
 -combineAltInfo TagProper       (TagTuple {})   = panic "Combining unboxed tuple with non-tuple result"
 +combineAltInfo (TagTuple {})    TagProper      = TagDunno  -- This can happen with rep-polymorphic result, see #26107
 +combineAltInfo TagProper       (TagTuple {})   = TagDunno  -- This can happen with rep-polymorphic result, see #26107
  combineAltInfo TagProper        TagProper      = TagProper
  combineAltInfo (TagTuple is1)  (TagTuple is2)  = TagTuple (zipWithEqual combineAltInfo is1 is2)
  combineAltInfo (TagTagged)      ti             = ti

m4/fp_gcc_supports_no_pie.m4

@@ -7,9 +7,9 @@ AC_DEFUN([FP_GCC_SUPPORTS_NO_PIE],
     AC_REQUIRE([AC_PROG_CC])
     AC_MSG_CHECKING([whether CC supports -no-pie])
     echo 'int main() { return 0; }' > conftest.c
 -   "$CC" $CONF_GCC_CC_OPTS_STAGE2 -c conftest.c
 +   "$CC" -c conftest.c
     # Some GCC versions only warn when passed an unrecognized flag.
 -   if "$CC" $CONF_GCC_LINKER_OPTS_STAGE2 -no-pie -Werror conftest.o -o conftest > conftest.txt 2>&1 && ! grep -i unrecognized conftest.txt > /dev/null 2>&1; then
 +   if "$CC" -no-pie -Werror conftest.o -o conftest > conftest.txt 2>&1 && ! grep -i unrecognized conftest.txt > /dev/null 2>&1; then
         CONF_GCC_SUPPORTS_NO_PIE=YES
         AC_MSG_RESULT([yes])
     else

m4/fptools_set_c_ld_flags.m4

@@ -109,6 +109,9 @@ AC_DEFUN([FPTOOLS_SET_C_LD_FLAGS],
          $2="$$2 -mcmodel=medium"
          ;;
 +    javascript*)
 +        $3="$$3 -sEXPORTED_RUNTIME_METHODS=HEAP8,HEAPU8"
++
      esac
      AC_MSG_RESULT([done])

testsuite/tests/rep-poly/T26107.hs

 +{-# LANGUAGE GADTs, UnboxedTuples #-}
 +module T26107 where
++
 +import Data.Kind
 +import GHC.Exts
++
 +type T :: TYPE rep -> Type
 +data T a where
 +  A :: T Bool
 +  B :: T (# #)
++
 +f :: forall rep (a :: TYPE rep). T a -> a
 +f A = True
 +f B = (# #)

testsuite/tests/rep-poly/all.T

@@ -41,6 +41,7 @@ test('T23883a', normal, compile_fail, [''])
  test('T23883b', normal, compile_fail, [''])
  test('T23883c', normal, compile_fail, [''])
  test('T23903', normal, compile_fail, [''])
 +test('T26107', normal, compile, ['-O'])
  test('EtaExpandDataCon', normal, compile, ['-O'])
  test('EtaExpandStupid1', normal, compile, ['-Wno-deprecated-flags'])

utils/ghc-toolchain/src/GHC/Toolchain/Tools/Link.hs

@@ -324,6 +324,10 @@ addPlatformDepLinkFlags archOs cc ccLink0 = do
      ArchOS ArchPPC OSAIX ->
        -- We need `-D_THREAD_SAFE` to unlock the thread-local `errno`.
        return $ ccLink2 & over _prgFlags (++["-D_THREAD_SAFE","-Wl,-bnotextro"])
 +    ArchOS ArchJavaScript OSGhcjs ->
 +      -- Since https://github.com/emscripten-core/emscripten/blob/main/ChangeLog.md#407---041525
 +      -- the emcc linker does not export the HEAP8 memory view which is used by the js RTS by default anymore.
 +      return $ ccLink2 & _prgFlags %++ "-sEXPORTED_RUNTIME_METHODS=HEAP8,HEAPU8"
      _ ->
        return ccLink2