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Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC

Commits:

a18fa3c1

by Cheng Shao at 2026-03-14T05:12:14-04:00

configure: make $LLVMAS default to $CC when $CcLlvmBackend is YES

This patch changes the $LLVMAS detection logic in configure so that
when it's not manually specified by the user, it defaults to $CC if
$CcLlvmBackend is YES. It's a more sensible default than auto-detected
clang from the environment, especially when cross-compiling, $CC as
the cross target's LLVM assembler is more compatible with the use case
than the system-wide clang. Fixes #26769.

2 changed files:

configure.ac
distrib/configure.ac.in

Changes:

configure.ac

@@ -542,9 +542,17 @@ FIND_LLVM_PROG([OPT], [opt], [$LlvmMinVersion], [$LlvmMaxVersion])
  OptCmd="$OPT"
  AC_SUBST([OptCmd])
 +dnl ** look to see if we have a C compiler using an llvm back end.
 +dnl
 +FP_CC_LLVM_BACKEND
 +AC_SUBST(CcLlvmBackend)
++
  dnl ** Which LLVM assembler to use?
  dnl --------------------------------------------------------------
  AC_ARG_VAR(LLVMAS,[Use as the path to LLVM's assembler (typically clang) [default=autodetect]])
 +if test "x$CcLlvmBackend" = "xYES" && test -z "$LLVMAS"; then
 +    LLVMAS="$CC"
 +fi
  FIND_LLVM_PROG([LLVMAS], [clang], [$LlvmMinVersion], [$LlvmMaxVersion])
  LlvmAsCmd="$LLVMAS"
  AC_SUBST([LlvmAsCmd])
@@ -622,11 +630,6 @@ else
      AC_SUBST([NeedLibatomic],[NO])
  fi
 -dnl ** look to see if we have a C compiler using an llvm back end.
 -dnl
 -FP_CC_LLVM_BACKEND
 -AC_SUBST(CcLlvmBackend)
+-
  FPTOOLS_SET_C_LD_FLAGS([target],[CFLAGS],[LDFLAGS],[IGNORE_LINKER_LD_FLAGS],[CPPFLAGS])
  FPTOOLS_SET_C_LD_FLAGS([build],[CONF_CC_OPTS_STAGE0],[CONF_GCC_LINKER_OPTS_STAGE0],[CONF_LD_LINKER_OPTS_STAGE0],[CONF_CPP_OPTS_STAGE0])
  FPTOOLS_SET_C_LD_FLAGS([target],[CONF_CC_OPTS_STAGE1],[CONF_GCC_LINKER_OPTS_STAGE1],[CONF_LD_LINKER_OPTS_STAGE1],[CONF_CPP_OPTS_STAGE1])

distrib/configure.ac.in

@@ -203,9 +203,17 @@ FIND_LLVM_PROG([OPT], [opt], [$LlvmMinVersion], [$LlvmMaxVersion])
  OptCmd="$OPT"
  AC_SUBST([OptCmd])
 +dnl ** look to see if we have a C compiler using an llvm back end.
 +dnl
 +FP_CC_LLVM_BACKEND
 +AC_SUBST(CcLlvmBackend)
++
  dnl ** Which LLVM assembler to use?
  dnl --------------------------------------------------------------
  AC_ARG_VAR(LLVMAS,[Use as the path to LLVM's assembler (typically clang) [default=autodetect]])
 +if test "x$CcLlvmBackend" = "xYES" && test -z "$LLVMAS"; then
 +    LLVMAS="$CC"
 +fi
  FIND_LLVM_PROG([LLVMAS], [clang], [$LlvmMinVersion], [$LlvmMaxVersion])
  LlvmAsCmd="$LLVMAS"
  AC_SUBST([LlvmAsCmd])