i386: Optimize pmovmskb on inverted vector to inversion of pmovmskb result [PR98461]

i386: Optimize pmovmskb on inverted vector to inversion of pmovmskb result [PR98461]

The following patch adds combine splitters to optimize:
-       vpcmpeqd        %ymm1, %ymm1, %ymm1
-       vpandn  %ymm1, %ymm0, %ymm0
        vpmovmskb       %ymm0, %eax
+       notl    %eax
etc. (for vectors with less than 32 elements with xorl instead of notl).

2020-12-30  Jakub Jelinek  <jakub@redhat.com>

	PR target/98461
	* config/i386/sse.md (<sse2_avx2>_pmovmskb): Add splitters
	for pmovmskb of NOT vector.

	* gcc.target/i386/sse2-pr98461.c: New test.
	* gcc.target/i386/avx2-pr98461.c: New test.