[i386] __builtin_ia32_stmxcsr could be pure

[i386] __builtin_ia32_stmxcsr could be pure

2017-06-21  Marc Glisse  <marc.glisse@inria.fr>

gcc/
	* config/i386/i386.c (struct builtin_isa): New field pure_p.
	Reorder for compactness.
	(def_builtin, def_builtin2, ix86_add_new_builtins): Handle pure_p.
	(def_builtin_pure, def_builtin_pure2): New functions.
	(ix86_init_mmx_sse_builtins) [__builtin_ia32_stmxcsr]: Mark as pure.

gcc/testsuite/
	* gcc.target/i386/getround.c: New file.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@249448 138bc75d-0d04-0410-961f-82ee72b054a4