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, 24 insertions, 0 deletions

diff --git a/gcc/configure.ac b/gcc/configure.ac
index 1676c40..67973b1 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -3202,6 +3202,19 @@ foo:	nop
 	   rm -f conftest],
 	  [AC_DEFINE(HAVE_GAS_PE_SECREL32_RELOC, 1,
 	    [Define if your assembler and linker support 32-bit section relative relocs via '.secrel32 label'.])])
+	# Test if the assembler supports the extended form of the .section
+	# directive that specifies section alignment.  LTO support uses this,
+	# but normally only after installation, so we warn but don't fail the
+	# configure if LTO is enabled but the assembler does not support it.
+	gcc_GAS_CHECK_FEATURE([.section with alignment], gcc_cv_as_section_has_align,
+	  [2,20,1],-fatal-warnings,[.section lto_test,"dr0"])
+	if test x$gcc_cv_as_section_has_align != xyes; then
+	  case ",$enable_languages," in
+	    *,lto,*)
+	      AC_MSG_WARN([LTO for $target requires binutils >= 2.20.1, but version found appears insufficient; LTO will not work until binutils is upgraded.])
+	      ;;
+	  esac
+	fi
 	;;
     esac
 
@@ -4270,6 +4283,17 @@ changequote([,])dnl
 		    AC_DEFINE(ENABLE_LTO, 1, [Define to enable LTO support.])
 		    enable_lto=yes
 		    AC_SUBST(enable_lto)
+		    # LTO needs to speak the platform's object file format, and has a
+		    # number of implementations of the required binary file access APIs.
+		    # ELF is the most common, and default.  We only link libelf if ELF
+		    # is indeed the selected format.
+		    LTO_BINARY_READER=${lto_binary_reader}
+		    LTO_USE_LIBELF=-lelf
+		    if test "x$lto_binary_reader" != "xlto-elf" ; then
+		      LTO_USE_LIBELF=
+		    fi
+		    AC_SUBST(LTO_BINARY_READER)
+		    AC_SUBST(LTO_USE_LIBELF)
 		    ;;
 		*) ;;
 	esac