re PR middle-end/46790 (EH failures in libstdc++ testsuite with --gc-sections and GNU ld 2.18)

	PR middle-end/46790
	* configure.ac (HAVE_LD_EH_GC_SECTIONS_BUG): New test.
	* configure: Regenerated.
	* config.in: Regenerated.
	* varasm.c (default_function_section): Return NULL
	if HAVE_LD_EH_GC_SECTIONS_BUG and decl has implicit
	section name.

From-SVN: r170565

5 files changed, 118 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cbad9a2..7c3d538 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2011-02-28  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/46790
+	* configure.ac (HAVE_LD_EH_GC_SECTIONS_BUG): New test.
+	* configure: Regenerated.
+	* config.in: Regenerated.
+	* varasm.c (default_function_section): Return NULL
+	if HAVE_LD_EH_GC_SECTIONS_BUG and decl has implicit
+	section name.
+
 2011-02-28  Martin Jambor  <mjambor@suse.cz>
 
 	* ipa-inline.c (cgraph_decide_inlining_of_small_functions): Fix
diff --git a/gcc/config.in b/gcc/config.in
index f3b0eee..584ec65 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -1171,6 +1171,13 @@
 #endif
 
 
+/* Define if your linker has buggy garbage collection of sections support when
+   .text.startup.foo like sections are used. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_LD_EH_GC_SECTIONS_BUG
+#endif
+
+
 /* Define if your PowerPC64 linker supports a large TOC. */
 #ifndef USED_FOR_TARGET
 #undef HAVE_LD_LARGE_TOC
diff --git a/gcc/configure b/gcc/configure
index 2da3716..a454946 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -25445,6 +25445,53 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld_eh_gc_sections" >&5
 $as_echo "$gcc_cv_ld_eh_gc_sections" >&6; }
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking linker EH garbage collection of sections bug" >&5
+$as_echo_n "checking linker EH garbage collection of sections bug... " >&6; }
+gcc_cv_ld_eh_gc_sections_bug=no
+if test $in_tree_ld = yes ; then
+  if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -lt 19 -o "$gcc_cv_gld_major_version" -lt 2 \
+     && test $in_tree_ld_is_elf = yes; then
+    gcc_cv_ld_eh_gc_sections_bug=yes
+  fi
+elif test x$gcc_cv_as != x -a x$gcc_cv_ld != x -a x$gcc_cv_objdump != x -a x$gcc_cv_as_comdat_group = xyes; then
+  gcc_cv_ld_eh_gc_sections_bug=yes
+  cat > conftest.s <<EOF
+	.section	.text
+.globl _start
+	.type _start, @function
+_start:
+	.long foo
+	.size _start, .-_start
+	.section	.text.startup.foo,"ax",@progbits
+	.type foo, @function
+foo:
+	.long 0
+	.size foo, .-foo
+	.section	.gcc_except_table.foo,"a",@progbits
+.L0:
+	.long 0
+	.section	.eh_frame,"a",@progbits
+	.long .L0
+EOF
+  if $gcc_cv_as -o conftest.o conftest.s > /dev/null 2>&1; then
+    if $gcc_cv_ld -o conftest conftest.o --entry=_start --gc-sections 2>&1 \
+	 | grep "gc-sections option ignored" > /dev/null; then
+      :
+    elif $gcc_cv_objdump -h conftest 2> /dev/null \
+	 | grep gcc_except_table > /dev/null; then
+      gcc_cv_ld_eh_gc_sections_bug=no
+    fi
+  fi
+  rm -f conftest.s conftest.o conftest
+fi
+if test x$gcc_cv_ld_eh_gc_sections_bug = xyes; then
+
+$as_echo "#define HAVE_LD_EH_GC_SECTIONS_BUG 1" >>confdefs.h
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_ld_eh_gc_sections_bug" >&5
+$as_echo "$gcc_cv_ld_eh_gc_sections_bug" >&6; }
+
 # --------
 # UNSORTED
 # --------
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 0c065e0..03a8cef 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -4097,6 +4097,51 @@ if test x$gcc_cv_ld_eh_gc_sections = xyes; then
 fi
 AC_MSG_RESULT($gcc_cv_ld_eh_gc_sections)
 
+AC_MSG_CHECKING(linker EH garbage collection of sections bug)
+gcc_cv_ld_eh_gc_sections_bug=no
+if test $in_tree_ld = yes ; then
+  if test "$gcc_cv_gld_major_version" -eq 2 -a "$gcc_cv_gld_minor_version" -lt 19 -o "$gcc_cv_gld_major_version" -lt 2 \
+     && test $in_tree_ld_is_elf = yes; then
+    gcc_cv_ld_eh_gc_sections_bug=yes
+  fi
+elif test x$gcc_cv_as != x -a x$gcc_cv_ld != x -a x$gcc_cv_objdump != x -a x$gcc_cv_as_comdat_group = xyes; then
+  gcc_cv_ld_eh_gc_sections_bug=yes
+  cat > conftest.s <<EOF
+	.section	.text
+.globl _start
+	.type _start, @function
+_start:
+	.long foo
+	.size _start, .-_start
+	.section	.text.startup.foo,"ax",@progbits
+	.type foo, @function
+foo:
+	.long 0
+	.size foo, .-foo
+	.section	.gcc_except_table.foo,"a",@progbits
+.L0:
+	.long 0
+	.section	.eh_frame,"a",@progbits
+	.long .L0
+EOF
+  if $gcc_cv_as -o conftest.o conftest.s > /dev/null 2>&1; then
+    if $gcc_cv_ld -o conftest conftest.o --entry=_start --gc-sections 2>&1 \
+	 | grep "gc-sections option ignored" > /dev/null; then
+      :
+    elif $gcc_cv_objdump -h conftest 2> /dev/null \
+	 | grep gcc_except_table > /dev/null; then
+      gcc_cv_ld_eh_gc_sections_bug=no
+    fi
+  fi
+  rm -f conftest.s conftest.o conftest
+fi
+if test x$gcc_cv_ld_eh_gc_sections_bug = xyes; then
+	AC_DEFINE(HAVE_LD_EH_GC_SECTIONS_BUG, 1,
+  [Define if your linker has buggy garbage collection of
+   sections support when .text.startup.foo like sections are used.])
+fi
+AC_MSG_RESULT($gcc_cv_ld_eh_gc_sections_bug)
+
 # --------
 # UNSORTED
 # --------
diff --git a/gcc/varasm.c b/gcc/varasm.c
index 76675cd..9887fe4 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -554,6 +554,15 @@ section *
 default_function_section (tree decl, enum node_frequency freq,
 			  bool startup, bool exit)
 {
+#if defined HAVE_LD_EH_GC_SECTIONS && defined HAVE_LD_EH_GC_SECTIONS_BUG
+  /* Old GNU linkers have buggy --gc-section support, which sometimes
+     results in .gcc_except_table* sections being garbage collected.  */
+  if (decl
+      && DECL_SECTION_NAME (decl)
+      && DECL_HAS_IMPLICIT_SECTION_NAME_P (decl))
+    return NULL;
+#endif
+
   if (!flag_reorder_functions
       || !targetm.have_named_sections)
     return NULL;