i386: Optimize pmovskb on zero_extend of subreg HI of pmovskb result [PR98461]

i386: Optimize pmovskb on zero_extend of subreg HI of pmovskb result [PR98461]

The following patch adds define_insn_and_split to optimize

       vpmovmskb       %xmm0, %eax
-       movzwl  %ax, %eax
        notl    %eax

and combine splitter to optimize

        pmovmskb        %xmm0, %eax
-       notl    %eax
-       movzwl  %ax, %eax
+       xorl    $65535, %eax

gcc/ChangeLog
	PR target/98461
	* config/i386/sse.md (*sse2_pmovskb_zexthisi): New
	define_insn_and_split for zero_extend of subreg HI of pmovskb
	result.
	(*sse2_pmovskb_zexthisi): Add new combine splitters for
	zero_extend of not of subreg HI of pmovskb result.

gcc/testsuite/ChangeLog
	* gcc.target/i386/sse2-pr98461-2.c: New test.