[commit: ghc] master: Do not hardcode the specific linker to use (5ddb307)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/5ddb307edf15c4d86e5c35c4063ec967424e19f2/ghc

>---------------------------------------------------------------

commit 5ddb307edf15c4d86e5c35c4063ec967424e19f2
Author: Moritz Angermann <moritz.angermann at gmail.com>
Date:   Thu May 11 18:12:33 2017 +0800

    Do not hardcode the specific linker to use
    
    This should be handled appropriately by a wrapper script around the compiler,
    if one wants to insist on the specific linker to be used.  Otherwise this
    breaks if the used compiler fails to understand this directive.
    
    I believe that using a specific linker should be part of the compilers
    toolchain, we delegate to and not hardcoded here in ghc.
    
    Reviewers: dfeuer, erikd, hvr, austin, rwbarton, bgamari
    
    Reviewed By: bgamari
    
    Subscribers: snowleopard, davean, dfeuer, thomie, erikd
    
    Differential Revision: https://phabricator.haskell.org/D3351


>---------------------------------------------------------------

5ddb307edf15c4d86e5c35c4063ec967424e19f2
 aclocal.m4              | 37 ++++++++++++++++++++++++++-----------
 configure.ac            |  2 +-
 distrib/configure.ac.in |  2 +-
 3 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/aclocal.m4 b/aclocal.m4
index d874d41..32e55cd 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -572,6 +572,7 @@ AC_DEFUN([FP_SET_CFLAGS_C99],
 # $5 is the name of the CPP flags variable
 AC_DEFUN([FPTOOLS_SET_C_LD_FLAGS],
 [
+    FIND_LD([$1],[UseLd])
     AC_MSG_CHECKING([Setting up $2, $3, $4 and $5])
     case $$1 in
     i386-*)
@@ -610,18 +611,14 @@ AC_DEFUN([FPTOOLS_SET_C_LD_FLAGS],
         ;;
     arm*linux*)
         # On arm/linux and arm/android, tell gcc to generate Arm
-        # instructions (ie not Thumb) and to link using the gold linker.
-        # Forcing LD to be ld.gold is done in FIND_LD m4 macro.
+        # instructions (ie not Thumb).
         $2="$$2 -marm"
-        $3="$$3 -fuse-ld=gold -Wl,-z,noexecstack"
+        $3="$$3 -Wl,-z,noexecstack"
         $4="$$4 -z noexecstack"
         ;;
 
     aarch64*linux*)
-        # On aarch64/linux and aarch64/android, tell gcc to link using the
-        # gold linker.
-        # Forcing LD to be ld.gold is done in FIND_LD m4 macro.
-        $3="$$3 -fuse-ld=gold -Wl,-z,noexecstack"
+        $3="$$3 -Wl,-z,noexecstack"
         $4="$$4 -z noexecstack"
         ;;
 
@@ -642,6 +639,15 @@ AC_DEFUN([FPTOOLS_SET_C_LD_FLAGS],
 
     esac
 
+    case $UseLd in
+         *ld.gold)
+         $3="$$3 -fuse-ld=gold"
+         ;;
+         *ld.bfd)
+         $3="$$3 -fuse-ld=bfd"
+         ;;
+    esac
+
     # If gcc knows about the stack protector, turn it off.
     # Otherwise the stack-smash handler gets triggered.
     echo 'int main(void) {return 0;}' > conftest.c
@@ -1991,11 +1997,12 @@ AC_DEFUN([FIND_LLVM_PROG],[
 # Find the version of `ld` to use. This is used in both in the top level
 # configure.ac and in distrib/configure.ac.in.
 #
-# $1 = the variable to set
+# $1 = the platform
+# $2 = the variable to set
 #
 AC_DEFUN([FIND_LD],[
     AC_CHECK_TARGET_TOOL([LD], [ld])
-    case $target in
+    case $1 in
         arm*linux*       | \
         aarch64*linux*   )
             # Arm and Aarch64 requires use of the binutils ld.gold linker.
@@ -2003,10 +2010,18 @@ AC_DEFUN([FIND_LD],[
             # arm-linux-androideabi, arm64-unknown-linux and
             # aarch64-linux-android
             AC_CHECK_TARGET_TOOL([LD_GOLD], [ld.gold])
-            $1="$LD_GOLD"
+            if test "$LD_GOLD" != ""; then
+                $2="$LD_GOLD"
+            elif test `$LD --version | grep -c "GNU gold"` -gt 0; then
+                AC_MSG_NOTICE([ld is ld.gold])
+                $2="$LD"
+            else
+                AC_MSG_WARN([could not find ld.gold, falling back to $LD])
+                $2="$LD"
+            fi
             ;;
         *)
-            $1="$LD"
+            $2="$LD"
             ;;
     esac
 ])
diff --git a/configure.ac b/configure.ac
index 0a0f790..73ee64d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -497,7 +497,7 @@ FP_SET_CFLAGS_C99([CC],[CONF_CC_OPTS_STAGE2],[CONF_CPP_OPTS_STAGE2])
 
 dnl ** Which ld to use?
 dnl --------------------------------------------------------------
-FIND_LD([LdCmd])
+FIND_LD([$target],[LdCmd])
 AC_SUBST([LdCmd])
 
 dnl ** Which nm to use?
diff --git a/distrib/configure.ac.in b/distrib/configure.ac.in
index ffa0574..cea3c49 100644
--- a/distrib/configure.ac.in
+++ b/distrib/configure.ac.in
@@ -86,7 +86,7 @@ AC_SUBST([OptCmd])
 
 dnl ** Which ld to use?
 dnl --------------------------------------------------------------
-FIND_LD([LdCmd])
+FIND_LD([$target],[LdCmd])
 AC_SUBST([LdCmd])
 
 FP_GCC_VERSION