[PATCH][X86] Fix rounding pattern similar to PR73350

["Koval, Julia" <julia dot koval at intel dot com>]

This is the same issue as PR73350 and PR80862 for disabling FP exceptions.

gcc -O0 -mavx512f -mavx512er returns exception
gcc -O2 -mavx512f -mavx512er returns nan

For this code:

#include <stdio.h>
#include <math.h>
#include <x86intrin.h>
#include <limits.h>
#include <float.h>

int main(int argc, char *argv[]) {
    __m512 a = _mm512_set1_ps((float) -1);
    __m512 b = _mm512_set1_ps((float) -1);
    _mm_setcsr( _MM_MASK_MASK &~
              (_MM_MASK_OVERFLOW|_MM_MASK_INVALID|_MM_MASK_DIV_ZERO) );
    __m512 result1 = _mm512_rsqrt28_round_ps(a, _MM_FROUND_NO_EXC );
    printf("%d %d\n", _MM_FROUND_CUR_DIRECTION, _MM_FROUND_NO_EXC);
    __m512 result2 = _mm512_rsqrt28_round_ps(a, _MM_FROUND_CUR_DIRECTION);

    printf("%g\n", result1[0] - result2[0]);

    return 0;
}

This patch fixes the issue.

gcc/
	* config/i386/i386.c: Fix rounding expand for new pattern
	* config/i386/subst.md: Fix pattern (parallel -> unspec)

Ok for trunk?

Thanks,
Julia

Attachment: 0001-fix.patch
Description: 0001-fix.patch