[patch] make default linker --hash-style configurable option

[ppluzhnikov@google.com (Paul Pluzhnikov)]

Greetings,

Several Linux distributions (e.g. Fedora) carry local patches that turn
on --hash-style=gnu for all links.

Attached is a proposed patch (originally by Satoru Takabayashi) that makes
default hash style a configure option.

Tested by doing native bootstrap and verifying that no --hash-style is
passed to the linker, and also configuring with --with-linker-hash-style=gnu
and verifying that --hash-style=gnu is then passed to the linker.

Ok for trunk?

Thanks,

P.S. Google has a blanket copyright assignment to FSF.

--
Paul Pluzhnikov


2011-04-04  Satoru Takabayashi  <satorux@google.com>
	    Paul Pluzhnikov  <ppluzhnikov@google.com>

	* gcc/doc/install.texi (Configuration): Document
	--with-linker-hash-style.
	* gcc/gcc.c (init_spec): Handle LINKER_HASH_STYLE.
	* gcc/config.in: Add LINKER_HASH_STYLE.
	* gcc/configure.ac: Add --with-linker-hash-style.
	* gcc/configure: Regenerate.


Index: gcc/doc/install.texi
===================================================================
--- gcc/doc/install.texi	(revision 171942)
+++ gcc/doc/install.texi	(working copy)
@@ -1657,6 +1657,11 @@
 support @option{--build-id} option, a warning is issued and the
 @option{--enable-linker-build-id} option is ignored.  The default is off.
 
+@item --with-linker-hash-style=@var{choice}
+Tells GCC to pass @option{--hash-style=@var{choice}} option to the
+linker for all final links. @var{choice} can be one of
+@samp{sysv}, @samp{gnu}, and @samp{both} where @samp{sysv} is the default.
+
 @item --enable-gnu-unique-object
 @itemx --disable-gnu-unique-object
 Tells GCC to use the gnu_unique_object relocation for C++ template
Index: gcc/gcc.c
===================================================================
--- gcc/gcc.c	(revision 171942)
+++ gcc/gcc.c	(working copy)
@@ -1438,7 +1438,8 @@
   }
 #endif
 
-#if defined LINK_EH_SPEC || defined LINK_BUILDID_SPEC
+#if defined LINK_EH_SPEC || defined LINK_BUILDID_SPEC || \
+    defined LINKER_HASH_STYLE
 # ifdef LINK_BUILDID_SPEC
   /* Prepend LINK_BUILDID_SPEC to whatever link_spec we had before.  */
   obstack_grow (&obstack, LINK_BUILDID_SPEC, sizeof(LINK_BUILDID_SPEC) - 1);
@@ -1447,6 +1448,16 @@
   /* Prepend LINK_EH_SPEC to whatever link_spec we had before.  */
   obstack_grow (&obstack, LINK_EH_SPEC, sizeof(LINK_EH_SPEC) - 1);
 # endif
+# ifdef LINKER_HASH_STYLE
+  /* Prepend --hash-style=LINKER_HASH_STYLE to whatever link_spec we had
+     before.  */
+  {
+    static const char hash_style[] = "--hash-style=";
+    obstack_grow (&obstack, hash_style, sizeof(hash_style) - 1);
+    obstack_grow (&obstack, LINKER_HASH_STYLE, sizeof(LINKER_HASH_STYLE) - 1);
+    obstack_1grow (&obstack, ' ');
+  }
+# endif
   obstack_grow0 (&obstack, link_spec, strlen (link_spec));
   link_spec = XOBFINISH (&obstack, const char *);
 #endif
Index: gcc/config.in
===================================================================
--- gcc/config.in	(revision 171942)
+++ gcc/config.in	(working copy)
@@ -1580,6 +1580,12 @@
 #endif
 
 
+/* The linker hash style */
+#ifndef USED_FOR_TARGET
+#undef LINKER_HASH_STYLE
+#endif
+
+
 /* Define to the name of the LTO plugin DSO that must be passed to the
    linker's -plugin=LIB option. */
 #ifndef USED_FOR_TARGET
Index: gcc/configure.ac
===================================================================
--- gcc/configure.ac	(revision 171942)
+++ gcc/configure.ac	(working copy)
@@ -4936,6 +4936,30 @@
 fi
 
 
+# Specify what hash style to use by default.
+AC_ARG_WITH([linker-hash-style],
+[AC_HELP_STRING([--with-linker-hash-style={sysv,gnu,both}],
+                [specify the linker hash style])],
+[case x"$withval" in
+   xsysv)
+     LINKER_HASH_STYLE=sysv
+     ;;
+   xgnu)
+     LINKER_HASH_STYLE=gnu
+     ;;
+   xboth)
+     LINKER_HASH_STYLE=both
+     ;;
+   *)
+     AC_MSG_ERROR([$withval is an invalid option to --with-linker-hash-style])
+     ;;
+ esac],
+[LINKER_HASH_STYLE=''])
+if test x"${LINKER_HASH_STYLE}" != x; then
+  AC_DEFINE_UNQUOTED(LINKER_HASH_STYLE, "$LINKER_HASH_STYLE",
+                                         [The linker hash style])
+fi
+
 # Configure the subdirectories
 # AC_CONFIG_SUBDIRS($subdirs)
 
Index: gcc/configure
===================================================================
--- gcc/configure	(revision 171942)
+++ gcc/configure	(working copy)
@@ -913,6 +913,7 @@
 with_slibdir
 enable_plugin
 enable_libquadmath_support
+with_linker_hash_style
 '
       ac_precious_vars='build_alias
 host_alias
@@ -1663,6 +1664,8 @@
                           with the compiler
   --with-system-zlib      use installed libz
   --with-slibdir=DIR      shared libraries in DIR [LIBDIR]
+  --with-linker-hash-style={sysv,gnu,both}
+                          specify the linker hash style
 
 Some influential environment variables:
   CC          C compiler command
@@ -17505,7 +17508,7 @@
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 17508 "configure"
+#line 17511 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -17611,7 +17614,7 @@
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 17614 "configure"
+#line 17617 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -26461,6 +26464,36 @@
 fi
 
 
+# Specify what hash style to use by default.
+
+# Check whether --with-linker-hash-style was given.
+if test "${with_linker_hash_style+set}" = set; then :
+  withval=$with_linker_hash_style; case x"$withval" in
+     xsysv)
+       LINKER_HASH_STYLE=sysv
+       ;;
+     xgnu)
+       LINKER_HASH_STYLE=gnu
+       ;;
+     xboth)
+       LINKER_HASH_STYLE=both
+       ;;
+     *)
+       as_fn_error "$withval is an invalid option to --with-linker-hash-style" "$LINENO" 5
+       ;;
+   esac
+else
+  LINKER_HASH_STYLE=''
+fi
+
+if test x"${LINKER_HASH_STYLE}" != x; then
+
+cat >>confdefs.h <<_ACEOF
+#define LINKER_HASH_STYLE "$LINKER_HASH_STYLE"
+_ACEOF
+
+fi
+
 # Configure the subdirectories
 # AC_CONFIG_SUBDIRS($subdirs)