[patch] Pass -fuse-ld=gold to gccgo on targets supporting -fsplit-stack

[Matthias Klose]

Am 18.01.2014 03:03, schrieb Ian Lance Taylor:
> On Fri, Nov 29, 2013 at 5:29 AM, Matthias Klose <doko@ubuntu.com> wrote:
>> to get full advantage of the -fsplit-stack option, gccgo binaries have to be
>> linked with gold, not the bfd linker.  When the system linker defaults to the
>> bfd linker, then gccgo should explicitly use the gold linker, passing
>> fuse-ld=gold, unless another -fuse-ld option is present.  Tested with and
>> without having ld.gold on the system.
> 
> The change to libgo/configure.ac seems unrelated.

No, it is required.  Without it you would check (with ld.bfd as the default) the
help text of the ld.bfd linker, and not the one used for gccgo ($LD vs. $GOC).
The quoting fix to fix the underquoting is now required because the argument has
a comma now.

> I don't think you can use "which" in a configure script.  You need to
> use something like AC_PATH_PROG.

Ok, but I cannot do this directly.  gcc_cv_ld may already be an absolute path.
So now I'm checking the very same location as gcc_cv_ld first, then fall back to
AC_PATH_PROG.

updated patch attached.

  Matthias


-------------- next part --------------
# DP: Pass -fuse-ld=gold to gccgo on targets supporting -fsplit-stack

gcc/go/                                                                                      
        * gospec.c (lang_specific_driver): Pass -fuse-ld=gold on targets
        supporting -fsplit-stack, unless overwritten.                            
                                                                                             
gcc/                                                                                         
        * configure.ac: New define HAVE_GOLD_NON_DEFAULT.  
        * config.in: Regenerate.                                                  
                                                                                             
libgo/                                                                                       
        * configure.ac (libgo_cv_c_linker_supports_split_stack): Fix quoting. 
        Check the linker used by the gccgo driver.                            

Index: gcc/configure.ac
===================================================================
--- gcc/configure.ac	(revision 206924)
+++ gcc/configure.ac	(working copy)
@@ -2105,6 +2105,19 @@
 fi
 AC_MSG_RESULT($ld_is_gold)
 
+# Check to see if ld is used, and gold is available
+if test x$ld_is_gold = xno; then
+  if test -x ${gcc_cv_ld}.gold; then
+    gcc_cv_ld_gold=${gcc_cv_ld}.gold
+  else
+    AC_PATH_PROG(gcc_cv_ld_gold,${gcc_cv_ld}.gold,no)
+  fi
+  if test x$gcc_cv_ld_gold != xno; then
+    AC_DEFINE(HAVE_GOLD_NON_DEFAULT, 1,
+	      [Define if the gold linker is available as a non-default])
+  fi
+fi
+
 ORIGINAL_LD_FOR_TARGET=$gcc_cv_ld
 AC_SUBST(ORIGINAL_LD_FOR_TARGET)
 case "$ORIGINAL_LD_FOR_TARGET" in
Index: gcc/go/gospec.c
===================================================================
--- gcc/go/gospec.c	(revision 206924)
+++ gcc/go/gospec.c	(working copy)
@@ -117,6 +117,10 @@
   /* Whether the -S option was used.  */
   bool saw_opt_S = false;
 
+  /* "-fuse-ld=" if it appears on the command line.  */
+  bool saw_use_ld ATTRIBUTE_UNUSED = false;
+  int need_gold = 0;
+
   /* The first input file with an extension of .go.  */
   const char *first_go_file = NULL;  
 
@@ -217,6 +221,11 @@
 	    }
 
 	  break;
+
+	case OPT_fuse_ld_bfd:
+	case OPT_fuse_ld_gold:
+	  saw_use_ld = true;
+	  break;
 	}
     }
 
@@ -226,8 +235,14 @@
   shared_libgcc = 0;
 #endif
 
+#if defined(TARGET_CAN_SPLIT_STACK) && defined(HAVE_GOLD_NON_DEFAULT)
+  if (!saw_use_ld)
+    need_gold = 1;
+#endif
+
   /* Make sure to have room for the trailing NULL argument.  */
-  num_args = argc + need_math + shared_libgcc + (library > 0) * 5 + 10;
+  num_args = argc + need_math + shared_libgcc + need_gold +
+    (library > 0) * 5 + 10;
   new_decoded_options = XNEWVEC (struct cl_decoded_option, num_args);
 
   i = 0;
@@ -244,7 +259,15 @@
 		       &new_decoded_options[j]);
       j++;
     }
+#ifdef HAVE_GOLD_NON_DEFAULT
+  if (need_gold)
+    {
+      generate_option (OPT_fuse_ld_gold, NULL, 1, CL_DRIVER,
+		       &new_decoded_options[j]);
+      j++;
+    }
 #endif
+#endif
 
   /* NOTE: We start at 1 now, not 0.  */
   while (i < argc)
Index: libgo/configure.ac
===================================================================
--- libgo/configure.ac	(revision 206924)
+++ libgo/configure.ac	(working copy)
@@ -357,10 +357,10 @@
 dnl others.
 AC_CACHE_CHECK([whether linker supports split stack],
 [libgo_cv_c_linker_supports_split_stack],
-libgo_cv_c_linker_supports_split_stack=no
-if $LD --help 2>/dev/null | grep split-stack-adjust-size >/dev/null 2>&1; then
+[libgo_cv_c_linker_supports_split_stack=no
+if $GOC -Wl,--help 2>/dev/null | grep split-stack-adjust-size >/dev/null 2>&1; then
   libgo_cv_c_linker_supports_split_stack=yes
-fi)
+fi])
 if test "$libgo_cv_c_linker_supports_split_stack" = yes; then
   AC_DEFINE(LINKER_SUPPORTS_SPLIT_STACK, 1,
 	    [Define if the linker support split stack adjustments])