[Git][ghc/ghc][wip/supersven/add-LLVMAS-target] Make host --target optional

[Sven Tennie (@supersven)]

Sven Tennie pushed to branch wip/supersven/add-LLVMAS-target at Glasgow Haskell Compiler / GHC


Commits:
c7672883 by Sven Tennie at 2024-08-30T08:53:13+02:00
Make host --target optional

- - - - -


1 changed file:

- m4/fp_prog_llvm_as_args.m4


Changes:

=====================================
m4/fp_prog_llvm_as_args.m4
=====================================
@@ -7,10 +7,13 @@ AC_DEFUN([FP_PROG_LLVM_AS_ARGS],
 AC_REQUIRE([GHC_LLVM_TARGET_SET_VAR])
 AC_REQUIRE([GHC_LLVM_HOST_TARGET_SET_VAR])
 # Cross-compiling: We need to define the target triple for the LLVM assembler.
-# Otherwise, LLVMAS tries to build for the host architecture. Defining the host
-# target is not strictly necessary, but it usually helps to be specific about
-# the build options.
+# Otherwise, $LLVMAS tries to build for the host architecture.
 LlvmAsArgsTarget="--target=$LlvmTarget"
+# Usually, the installed LLVMAS should be able to assemble for the host. There
+# may be special setups for cross-compiling where this is not the case, because
+# only the last stage uses the LLVM backend (and thus LLVMAS.) If this happens,
+# we just set this variable to empty such that it will succeed as long as LLVMAS
+# exists.
 LlvmAsArgsHost="--target=$LlvmHostTarget"
 
 # Create a minimal LLVM IR file for testing
@@ -26,7 +29,12 @@ if $LLVMAS $LlvmAsArgsHost test.ll > /dev/null 2>&1 ; then
     AC_MSG_RESULT([yes])
 else
     AC_MSG_RESULT([no])
-    AC_MSG_ERROR([\$LLVMAS ($LLVMAS) does not support host flags: $LlvmAsArgsHost])
+    AC_MSG_WARN([\$LLVMAS ($LLVMAS) does not support host flags: $LlvmAsArgsHost.])
+    AC_MSG_WARN([Falling back to no flags (won't be able to build stages for the host architecture with \$LLVMAS).])
+    # Here LLVMAS cannot assemble for the host. I.e. we won't be able to use it
+    # to build intermediate GHC stages (with host target). This ressembles old
+    # behaviour and is added for backwards compatibility.
+    LlvmAsArgsHost=""
 fi
 
 AC_MSG_CHECKING([whether \$LLVMAS supports target flags passed by GHC when compiling])



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c76728835c71ed75eb48013c343b9a7ec7f24ba7

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c76728835c71ed75eb48013c343b9a7ec7f24ba7
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