re PR middle-end/46674 (Weak alias is mistakenly optimized away)

gcc/ChangeLog:

	PR middle-end/46674
	PR lto/43157
	* target.def (mangle_assembler_name): New target asm_out hook.
	* targhooks.c (default_mangle_assembler_name): Add default hook
	implementation.
	* targhooks.h (default_mangle_assembler_name): Add prototype.
	* lto-symtab.c (lto_symtab_register_decl): Use new hook when
	processing DECL_ASSEMBLER_NAMEs for lto symtabs.
	(lto_symtab_get_resolution): Likewise.
	(lto_cgraph_replace_node): Likewise.
	(lto_symtab_prevailing_decl): Likewise.
	* lto-streamer-out.c (write_symbol): Likewise.
	* doc/tm.texi.in (TARGET_MANGLE_ASSEMBLER_NAME): Add @hook directive.
	* doc/tm.texi: Regenerate.
	* config/i386/cygming.h (TARGET_MANGLE_ASSEMBLER_NAME): Define to
	point at i386_pe_mangle_assembler_name.
	* config/i386/winnt.c (i386_pe_mangle_assembler_name): New function.
	* config/i386/i386-protos.h (i386_pe_mangle_assembler_name): Add
	prototype.

lto-plugin/ChangeLog:

	PR middle-end/46674
	PR lto/43157
	* configure.ac (SYM_STYLE): Don't AC_DEFINE.
	* lto-plugin.c (sym_style): Don't use it; default to ss_none.
	* configure: Regenerate.
	* config.h.in: Likewise.

gcc/testsuite/ChangeLog:

	PR middle-end/46674
	PR lto/43157
	* gcc.dg/pr43157.c: New file.

From-SVN: r167688