Improved V1TI (and V2DI) mode equality/inequality on x86_64.

Improved V1TI (and V2DI) mode equality/inequality on x86_64.

This patch improves support for vector equality and inequality of
V1TImode vectors, and V2DImode vectors with sse2 but not sse4.
Consider the three functions below:

typedef unsigned int uv4si __attribute__ ((__vector_size__ (16)));
typedef unsigned long long uv2di __attribute__ ((__vector_size__ (16)));
typedef unsigned __int128 uv1ti __attribute__ ((__vector_size__ (16)));

uv4si eq_v4si(uv4si x, uv4si y) { return x == y; }
uv2di eq_v2di(uv2di x, uv2di y) { return x == y; }
uv1ti eq_v1ti(uv1ti x, uv1ti y) { return x == y; }

These all perform vector comparisons of 128bit SSE2 registers, generating
the result as a vector, where ~0 (all 1 bits) represents true and a zero
represents false.  eq_v4si is trivially implemented by x86_64's pcmpeqd
instruction. This patch improves the other two cases:

For v2di, gcc -O2 currently generates:

	movq    %xmm0, %rdx
        movq    %xmm1, %rax
        movdqa  %xmm0, %xmm2
        cmpq    %rax, %rdx
        movhlps %xmm2, %xmm3
        movhlps %xmm1, %xmm4
        sete    %al
        movq    %xmm3, %rdx
        movzbl  %al, %eax
        negq    %rax
        movq    %rax, %xmm0
        movq    %xmm4, %rax
        cmpq    %rax, %rdx
        sete    %al
        movzbl  %al, %eax
        negq    %rax
        movq    %rax, %xmm5
        punpcklqdq      %xmm5, %xmm0
        ret

but with this patch we now generate:

        pcmpeqd %xmm0, %xmm1
        pshufd  $177, %xmm1, %xmm0
        pand    %xmm1, %xmm0
        ret

where the results of a V4SI comparison are shuffled and bit-wise ANDed
to produce the desired result.  There's no change in the code generated
for "-O2 -msse4" where the compiler generates a single "pcmpeqq" insn.

For V1TI mode, the results are equally dramatic, where the current -O2
output looks like:

        movaps  %xmm0, -40(%rsp)
        movq    -40(%rsp), %rax
        movq    -32(%rsp), %rdx
        movaps  %xmm1, -24(%rsp)
        movq    -24(%rsp), %rcx
        movq    -16(%rsp), %rsi
        xorq    %rcx, %rax
        xorq    %rsi, %rdx
        orq     %rdx, %rax
        sete    %al
        xorl    %edx, %edx
        movzbl  %al, %eax
        negq    %rax
        adcq    $0, %rdx
        movq    %rax, %xmm2
        negq    %rdx
        movq    %rdx, -40(%rsp)
        movhps  -40(%rsp), %xmm2
        movdqa  %xmm2, %xmm0
        ret

with this patch we now generate:

        pcmpeqd %xmm0, %xmm1
        pshufd  $177, %xmm1, %xmm0
        pand    %xmm1, %xmm0
        pshufd  $78, %xmm0, %xmm1
        pand    %xmm1, %xmm0
        ret

performing a V2DI comparison, followed by a shuffle and pand, and with
-O2 -msse4 take advantages of SSE4.1's pcmpeqq:

        pcmpeqq %xmm0, %xmm1
        pshufd  $78, %xmm1, %xmm0
        pand    %xmm1, %xmm0
        ret

2022-05-13  Roger Sayle  <roger@nextmovesoftware.com>
	    Uroš Bizjak  <ubizjak@gmail.com>

gcc/ChangeLog
	* config/i386/sse.md (vec_cmpeqv2div2di): Enable for TARGET_SSE2.
	For !TARGET_SSE4_1, expand as a V4SI vector comparison, followed
	by a pshufd and pand.
	(vec_cmpeqv1tiv1ti): New define_expand implementing V1TImode
	vector equality as a V2DImode vector comparison (see above),
	followed by a pshufd and pand.

gcc/testsuite/ChangeLog
	* gcc.target/i386/sse2-v1ti-veq.c: New test case.
	* gcc.target/i386/sse2-v1ti-vne.c: New test case.