re PR target/39118 (x86_64 red zone violation)

re PR target/39118 (x86_64 red zone violation)

	PR target/39118
	* config/i386/i386.md (UNSPEC_MEMORY_BLOCKAGE): New constant.
	(memory_blockage): New expander.
	(*memory_blockage): New insn pattern.
	* config/i386/i386.c (ix86_expand_prologue): Use memory_blockage
	instead of general blockage at the end of function prologue when
	frame pointer is used to access red zone area.  Do not emit blockage
	when profiling, it is emitted in generic code.
	(ix86_expand_epilogue): Emit memory_blockage at the beginning of
	function epilogue when frame pointer is used to access red zone area.

From-SVN: r144100