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.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@158762 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 19 insertions, 11 deletions

diff --git a/configure.ac b/configure.ac
index c46fc4d9946..1ae21407cb8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1637,17 +1637,8 @@ AC_ARG_ENABLE(lto,
 enable_lto=$enableval,
 enable_lto=yes; default_enable_lto=yes)
 
-ACX_ELF_TARGET_IFELSE([],
-if test x"$default_enable_lto" = x"yes" ; then
-  enable_lto=no
-else
-  if test x"$enable_lto" = x"yes"; then
-    AC_MSG_ERROR([LTO support requires an ELF target.])
-  fi
-fi
-default_enable_lto=no)
 
-if test x"$enable_lto" = x"yes" ; then
+ACX_ELF_TARGET_IFELSE([if test x"$enable_lto" = x"yes" ; then
   # Make sure that libelf.h and gelf.h are available.
   AC_ARG_WITH(libelf, [  --with-libelf=PATH       Specify prefix directory for the installed libelf package
                           Equivalent to --with-libelf-include=PATH/include
@@ -1783,7 +1774,24 @@ to specify its location.])
   # Flags needed for libelf.
   AC_SUBST(libelflibs)
   AC_SUBST(libelfinc)
-fi
+fi],[if test x"$default_enable_lto" = x"yes" ; then
+    # On non-ELF platforms, LTO must be explicitly enabled.
+    enable_lto=no
+  else
+  # Apart from ELF platforms, only Windows supports LTO so far.  It
+  # would also be nice to check the binutils support, but we don't
+  # have gcc_GAS_CHECK_FEATURE available here.  For now, we'll just
+  # warn during gcc/ subconfigure; unless you're bootstrapping with
+  # -flto it won't be needed until after installation anyway.
+    case $target in
+      *-cygwin*|*-mingw*) ;;
+      *) if test x"$enable_lto" = x"yes"; then
+	AC_MSG_ERROR([LTO support is not enabled for this target.])
+        fi
+      ;;
+    esac
+  fi
+  default_enable_lto=no])
 
 
 # By default, C is the only stage 1 language.