re PR lto/42776 (LTO doesn't work on non-ELF platforms.)

ChangeLog:

	PR lto/42776
	* configure.ac (--enable-lto): Refactor handling so libelf tests
	are only performed inside then-clause of ACX_ELF_TARGET_IFELSE,
	and allow LTO to be explicitly enabled on non-ELF platforms that
	are known to support it inside else-clause.
	* configure: Regenerate.

gcc/ChangeLog:

	PR lto/42776
	* configure.ac (gcc_cv_as_section_has_align): Set if installed
	binutils supports extended .section directive needed by LTO, or
	warn if older binutils found.
	(LTO_BINARY_READER): New AC_SUBST'd variable.
	(LTO_USE_LIBELF): Likewise.
	* gcc/config.gcc (lto_binary_reader): New target-specific configure
	variable.
	* gcc/Makefile.in (LTO_BINARY_READER): Import AC_SUBST'd autoconf var.
	(LTO_USE_LIBELF): Likewise.
	* configure: Regenerate.

	* collect2.c (is_elf): Rename from this ...
	(is_elf_or_coff): ... to this, and recognize and allow i386 COFF
	 object files in addition to ELF-formatted ones.
	(scan_prog_file): Caller updated.  Also allow for LTO info marker
	symbol to be prefixed or not by an extra underscore.

	* config/i386/t-cygming (winnt.o): Also depend on LTO_STREAMER_H.
	* config/i386/winnt.c: Also #include lto-streamer.h
	(i386_pe_asm_named_section): Specify 1-byte section alignment for
	LTO named sections.
	(i386_pe_asm_output_aligned_decl_common): Add comment.
	(i386_pe_maybe_record_exported_symbol): Allow decl arg to be NULL.

gcc/lto/ChangeLog:

	PR lto/42776
	* Make-lang.in (LTO_OBJS): Use LTO_BINARY_READER instead of
	hardcoding 'lto-elf.o'.
	($(LTO_EXE)): Use LTO_USE_LIBELF instead of hardcoding '-lelf'.

	* lto-coff.h: New file.
	* lto-coff.c: Likewise.

gcc/testsuite/ChangeLog:

	PR lto/42776
	* lib/lto.exp (lto_prune_vis_warns): New function.
	(lto-link-and-maybe-run): Call it.

From-SVN: r158762

1 files changed, 10 insertions, 8 deletions

diff --git a/gcc/collect2.c b/gcc/collect2.c
index 120369a..ad66202 100644
--- a/gcc/collect2.c
+++ b/gcc/collect2.c
@@ -2548,19 +2548,21 @@ write_aix_file (FILE *stream, struct id *list)
    be in ELF format.  */
 
 static bool
-is_elf (const char *prog_name)
+is_elf_or_coff (const char *prog_name)
 {
   FILE *f;
   char buf[4];
   static char magic[4] = { 0x7f, 'E', 'L', 'F' };
+  static char coffmag[2] = { 0x4c, 0x01 };
 
-  f = fopen (prog_name, "r");
+  f = fopen (prog_name, "rb");
   if (f == NULL)
     return false;
   if (fread (buf, sizeof (buf), 1, f) != 1)
     buf[0] = 0;
   fclose (f);
-  return memcmp (buf, magic, sizeof (magic)) == 0;
+  return memcmp (buf, magic, sizeof (magic)) == 0
+	|| memcmp (buf, coffmag, sizeof (coffmag)) == 0;
 }
 
 /* Generic version to scan the name list of the loaded program for
@@ -2587,10 +2589,10 @@ scan_prog_file (const char *prog_name, scanpass which_pass,
   if (which_pass == PASS_SECOND)
     return;
 
-  /* LTO objects must be in ELF format.  This check prevents
+  /* LTO objects must be in a known format.  This check prevents
      us from accepting an archive containing LTO objects, which
      gcc cannnot currently handle.  */
-  if (which_pass == PASS_LTOINFO && !is_elf (prog_name))
+  if (which_pass == PASS_LTOINFO && !is_elf_or_coff (prog_name))
     return;
 
   /* If we do not have an `nm', complain.  */
@@ -2670,9 +2672,9 @@ scan_prog_file (const char *prog_name, scanpass which_pass,
           /* Look for the LTO info marker symbol, and add filename to
              the LTO objects list if found.  */
           for (p = buf; (ch = *p) != '\0' && ch != '\n'; p++)
-            if (ch == ' '
-		&& (strncmp (p + 1, "__gnu_lto_v1", 12) == 0)
-		&& ISSPACE (p[13]))
+            if (ch == ' '  && p[1] == '_' && p[2] == '_'
+		&& (strncmp (p + (p[3] == '_' ? 2 : 1), "__gnu_lto_v1", 12) == 0)
+		&& ISSPACE (p[p[3] == '_' ? 14 : 13]))
               {
                 add_lto_object (&lto_objects, prog_name);