https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106113
Bug ID: 106113
Summary: wrong codegen for _mm_[u]comineq_{ss,sd} and need to
return PF result.
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: lingling.kong7 at gmail dot com
Target Milestone: ---
https://gcc.godbolt.org/z/svoqvKs55
for _mm_ucomineq_ss,
according to the instruction description，
Operation
(V)UCOMISS (all versions)
RESULT := UnorderedCompare(DEST[31:0] <> SRC[31:0]) {
(* Set EFLAGS *) CASE (RESULT) OF
UNORDERED: ZF,PF,CF := 111;
GREATER_THAN: ZF,PF,CF := 000;
LESS_THAN: ZF,PF,CF := 001;
EQUAL: ZF,PF,CF := 100;
ESAC;
OF, AF, SF := 0; }
result need to set PF = 1,
but now generate code for `_mm_ucomineq_ss` is
# gcc -O3 -mavx512f
xorl %eax, %eax
vucomiss %xmm1, %xmm0
setne %al
ret
it ignore PF result, the codegen in llvm for this is correct.
We also could refer to the codegen in gcc for '_mm_comi_round_ss(__A, __B, 4,
_MM_FROUND_NO_EXC); '
