[Bug target/96243] New: For vector compare to mask register, UNSPEC is needed instead of comparison operator

[crazylht at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96243

            Bug ID: 96243
           Summary: For vector compare to mask register, UNSPEC is needed
                    instead of comparison operator
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: crazylht at gmail dot com
  Target Milestone: ---
            Target: i386, x86-64

When tring to relax 

 (define_expand "<avx512>_eq<mode>3<mask_scalar_merge_name>"
   [(set (match_operand:<avx512fmaskmode> 0 "register_operand")
-       (unspec:<avx512fmaskmode>
-         [(match_operand:VI48_AVX512VL 1 "nonimmediate_operand")
-          (match_operand:VI48_AVX512VL 2 "nonimmediate_operand")]
-         UNSPEC_MASKED_EQ))]
+       (eq:<avx512fmaskmode>
+         (match_operand:VI48_AVX512VL 1 "nonimmediate_operand")
+          (match_operand:VI48_AVX512VL 2 "nonimmediate_operand")))]
   "TARGET_AVX512F"
   "ix86_fixup_binary_operands_no_copy (EQ, <MODE>mode, operands);")

I got runtime failure from gcc.target/i386/avx512vl-vpcmpeqq-2.c, that's
because cse will take (eq:QI (V4DI: 90) (V4DI: 91)) as a boolean value and do
some optimization, that's not correct for vector compare, also others places
like combine hold the same assumption.

The pattern like 

(define_insn "*<avx512>_cmp<mode>3<mask_scalar_merge_name><round_saeonly_name>"
  [(set (match_operand:<avx512fmaskmode> 0 "register_operand" "=k")
        (match_operator:<avx512fmaskmode> 3 "ix86_comparison_int_operator"
          [(match_operand:VI48_AVX512VL 1 "register_operand" "v")
           (match_operand:VI48_AVX512VL 2 "nonimmediate_operand"
"<round_saeonly_constraint>")]))]
  "TARGET_AVX512F && <round_saeonly_mode512bit_condition>"
  "vpcmp<ssemodesuffix>\t{%I3, <round_saeonly_mask_scalar_merge_op4>%2, %1,
%0<mask_scalar_merge_operand4>|%0<mask_scalar_merge_operand4>, %1,
%2<round_saeonly_mask_scalar_merge_op4>, %I3}"
  [(set_attr "type" "ssecmp")
   (set_attr "length_immediate" "1")
   (set_attr "prefix" "evex")
   (set_attr "mode" "<sseinsnmode>")])


Need to be fixed.