Optimize memory broadcast for constant vector under AVX512.

Optimize memory broadcast for constant vector under AVX512.

For constant vector having one duplicated value, there's no need to put
whole vector in the constant pool, using embedded broadcast instead.

2020-07-09  Hongtao Liu  <hongtao.liu@intel.com>

gcc/ChangeLog:

	PR target/87767
	* config/i386/i386-features.c
	(replace_constant_pool_with_broadcast): New function.
	(constant_pool_broadcast): Ditto.
	(class pass_constant_pool_broadcast): New pass.
	(make_pass_constant_pool_broadcast): Ditto.
	(remove_partial_avx_dependency): Call
	replace_constant_pool_with_broadcast under TARGET_AVX512F, it
	would save compile time when both pass rpad and cpb are
	available.
	(remove_partial_avx_dependency_gate): New function.
	(class pass_remove_partial_avx_dependency::gate): Call
	remove_partial_avx_dependency_gate.
	* config/i386/i386-passes.def: Insert new pass after combine.
	* config/i386/i386-protos.h
	(make_pass_constant_pool_broadcast): Declare.
	* config/i386/sse.md (*avx512dq_mul<mode>3<mask_name>_bcst):
	New define_insn.
	(*avx512f_mul<mode>3<mask_name>_bcst): Ditto.
	* config/i386/avx512fintrin.h (_mm512_set1_ps,
	_mm512_set1_pd,_mm512_set1_epi32, _mm512_set1_epi64): Adjusted.

gcc/testsuite/ChangeLog:

	PR target/87767
	* gcc.target/i386/avx2-broadcast-pr87767-1.c: New test.
	* gcc.target/i386/avx512f-broadcast-pr87767-1.c: New test.
	* gcc.target/i386/avx512f-broadcast-pr87767-2.c: New test.
	* gcc.target/i386/avx512f-broadcast-pr87767-3.c: New test.
	* gcc.target/i386/avx512f-broadcast-pr87767-4.c: New test.
	* gcc.target/i386/avx512f-broadcast-pr87767-5.c: New test.
	* gcc.target/i386/avx512f-broadcast-pr87767-6.c: New test.
	* gcc.target/i386/avx512f-broadcast-pr87767-7.c: New test.
	* gcc.target/i386/avx512vl-broadcast-pr87767-1.c: New test.
	* gcc.target/i386/avx512vl-broadcast-pr87767-1.c: New test.
	* gcc.target/i386/avx512vl-broadcast-pr87767-2.c: New test.
	* gcc.target/i386/avx512vl-broadcast-pr87767-3.c: New test.
	* gcc.target/i386/avx512vl-broadcast-pr87767-4.c: New test.
	* gcc.target/i386/avx512vl-broadcast-pr87767-5.c: New test.
	* gcc.target/i386/avx512vl-broadcast-pr87767-6.c: New test.