i386.c (ix86_expand_builtin): If gather mask argument is known to have all high bits...

i386.c (ix86_expand_builtin): If gather mask argument is known to have all high bits set...

	* config/i386/i386.c (ix86_expand_builtin): If gather mask
	argument is known to have all high bits set, pass pc_rtx as
	second argument to the expander instead of op0.
	* config/i386/sse.md (*avx2_gathersi<mode>_2,
	*avx2_gatherdi<mode>_2): New patterns.
	* config/i386/avx2intrin.h (_mm256_i32gather_pd,
	_mm256_i64gather_pd, _mm256_i32gather_ps): Set mask using
	_mm256_cmp_pd with zero vector arguments and _CMP_EQ_OQ instead of
	_mm256_set1_pd.

From-SVN: r181090