3.4 PATCH: Test HAVE_GAS_SHF_MERGE at runtime

[Rainer Orth <ro at TechFak dot Uni-Bielefeld dot DE>]

Testing my IRIX 6 O32 integration patch with GNU as revealed an additional
problem: while gas supports SHF_MERGE, the O32 libgcc_s.so.1 fails to link
with the native ld:

ld: WARNING 86 : Section .rodata.cst4 of input file libgcc/mabi=32/_fixunssfsi.o not included as output.
ld: WARNING 86 : Section .rodata.cst4 of input file libgcc/mabi=32/_si_to_sf.o not included as output.
ld: WARNING 86 : Section .rodata.cst8 of input file libgcc/mabi=32/_floatdidf.o not included as output.
ld: WARNING 86 : Section .rodata.cst8 of input file libgcc/mabi=32/_floatdisf.o not included as output.
ld: WARNING 86 : Section .rodata.cst8 of input file libgcc/mabi=32/_fixunsdfsi.o not included as output.
ld: WARNING 86 : Section .rodata.cst8 of input file libgcc/mabi=32/_fixunsdfdi.o not included as output.
ld: WARNING 86 : Section .rodata.cst8 of input file libgcc/mabi=32/_fixunssfdi.o not included as output.
ld: WARNING 86 : Section .rodata.cst8 of input file libgcc/mabi=32/_si_to_df.o not included as output.
ld: FATAL   87 : Input sections have not been specified for inclusion in a.out.  This is typically due to omissions in the -elspec file. See error messages above.
collect2: ld returned 4 exit status
make[3]: *** [mabi=32/libgcc_s_mabi=32.so] Error 1

I had the same problem with the mips-sgi-irix6o32 configuration, where I
disabled HAVE_GAS_SHF_MERGE in iris5gas.h.  A similar change needs to go
into a (new, to be submitted with the rest of the IRIX 6 cleanup/O32
integration patch) iris6gas.h, only disabling this for O32 where the linker
cannot support it:

/* Disable SHF_MERGE support.  Even if gas supports it, the IRIX 6 O32 ld
   does not without a special elspec(5) file.

   FIXME: Only do this it not using GNU ld.  */
#if HAVE_GAS_SHF_MERGE
#undef HAVE_GAS_SHF_MERGE
#define HAVE_GAS_SHF_MERGE (mips_abi == ABI_32 ? 0 : 1)
#endif /* HAVE_GAS_SHF_MERGE */

So the current compile-time tests for HAVE_GAS_SHF_MERGE need to be
performed at runtime, and the configure test must result in the macro being
defined as either 0 or 1 one instead leaving it undefined in the former
case.  The following patch allows this.  The ability will be used as soon
as I submit the mips-specific parts of the integration patch.

Bootstrapped without regressions on mips-sgi-irix6.5 (with the complete
patch set above).

Ok for mainline?

	Rainer

-----------------------------------------------------------------------------
Rainer Orth, Faculty of Technology, Bielefeld University


Thu Sep 18 00:25:52 2003  Rainer Orth  <ro@TechFak.Uni-Bielefeld.DE>

	* configure.in (HAVE_GAS_SHF_MERGE): Always define to test result.
	Update description.
	* configure: Regenerate.
	* config.in: Likewise.
	* dwarf2out.c (DEBUG_STR_SECTION_FLAGS): Test for
	HAVE_GAS_SHF_MERGE value. 
	* varasm.c (mergeable_string_section): Likewise.
	(mergeable_constant_section): Likewise.

Index: gcc/configure.in
===================================================================
RCS file: /cvs/gcc/gcc/gcc/configure.in,v
retrieving revision 1.726
diff -u -p -b -r1.726 configure.in
--- gcc/configure.in	10 Sep 2003 00:13:00 -0000	1.726
+++ gcc/configure.in	22 Sep 2003 19:55:37 -0000
@@ -1966,9 +1966,10 @@ fi
 
 gcc_GAS_CHECK_FEATURE(section merging support, gcc_cv_as_shf_merge,
  [elf,2,12,0], [--fatal-warnings],
- [.section .rodata.str, "aMS", @progbits, 1],,
- [AC_DEFINE(HAVE_GAS_SHF_MERGE, 1,
-[Define if your assembler supports marking sections with SHF_MERGE flag.])])
+ [.section .rodata.str, "aMS", @progbits, 1])
+AC_DEFINE_UNQUOTED(HAVE_GAS_SHF_MERGE,
+  [`if test $gcc_cv_as_shf_merge = yes; then echo 1; else echo 0; fi`],
+[Define 0/1 if your assembler supports marking sections with SHF_MERGE flag.])
 
 # Thread-local storage - the check is heavily parametrized.
 conftest_s=
Index: gcc/dwarf2out.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/dwarf2out.c,v
retrieving revision 1.450
diff -u -p -b -r1.450 dwarf2out.c
--- gcc/dwarf2out.c	11 Sep 2003 13:41:56 -0000	1.450
+++ gcc/dwarf2out.c	22 Sep 2003 19:55:38 -0000
@@ -3812,14 +3826,10 @@ static int maybe_emit_file (int);
 #endif
 
 /* Section flags for .debug_str section.  */
-#ifdef HAVE_GAS_SHF_MERGE
 #define DEBUG_STR_SECTION_FLAGS \
-  (flag_merge_constants						\
+  (HAVE_GAS_SHF_MERGE && flag_merge_constants			\
    ? SECTION_DEBUG | SECTION_MERGE | SECTION_STRINGS | 1	\
    : SECTION_DEBUG)
-#else
-#define DEBUG_STR_SECTION_FLAGS	SECTION_DEBUG
-#endif
 
 /* Labels we insert at beginning sections we can reference instead of
    the section names themselves.  */
Index: gcc/varasm.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/varasm.c,v
retrieving revision 1.383
diff -u -p -b -r1.383 varasm.c
--- gcc/varasm.c	9 Sep 2003 13:37:17 -0000	1.383
+++ gcc/varasm.c	22 Sep 2003 19:55:41 -0000
@@ -562,8 +562,7 @@ mergeable_string_section (tree decl ATTR
 			  unsigned HOST_WIDE_INT align ATTRIBUTE_UNUSED,
 			  unsigned int flags ATTRIBUTE_UNUSED)
 {
-#ifdef HAVE_GAS_SHF_MERGE
-  if (flag_merge_constants
+  if (HAVE_GAS_SHF_MERGE && flag_merge_constants
       && TREE_CODE (decl) == STRING_CST
       && TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE
       && align <= 256
@@ -625,7 +624,7 @@ mergeable_string_section (tree decl ATTR
 	    }
 	}
     }
-#endif
+
   readonly_data_section ();
 }
 
@@ -636,10 +635,9 @@ mergeable_constant_section (enum machine
 			    unsigned HOST_WIDE_INT align ATTRIBUTE_UNUSED,
 			    unsigned int flags ATTRIBUTE_UNUSED)
 {
-#ifdef HAVE_GAS_SHF_MERGE
   unsigned int modesize = GET_MODE_BITSIZE (mode);
 
-  if (flag_merge_constants
+  if (HAVE_GAS_SHF_MERGE && flag_merge_constants
       && mode != VOIDmode
       && mode != BLKmode
       && modesize <= align
@@ -654,7 +652,7 @@ mergeable_constant_section (enum machine
       named_section_flags (name, flags);
       return;
     }
-#endif
+
   readonly_data_section ();
 }