https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106329
Bug ID: 106329
Summary: No optimization for SVE pfalse predicate
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: yyc1992 at gmail dot com
Target Milestone: ---
If a known-all-false predicate is used on an SVE intrinsic, the result should
be fully no-op, undefined, zeroing and no actual instruction (other than
potentially returning a zero) should be generated. This does not seem to be
happening even when a `svpfalse_b()` is explicitly passed in as the predicate.
As an example,
```
svfloat64_t add(svfloat64_t a, svfloat64_t b)
{
return svadd_x(svpfalse_b(), a, b);
}
```
is being compiled to
```
pfalse p0.b
fadd z0.d, p0/m, z0.d, z1.d
ret
```
when it could simply be an empty function.
