https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106326
Bug ID: 106326
Summary: _m and _z version of SVE instrinsics not optimized to
predicate-free version
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: ---
The following code should generate a predicate-free fadd instruction since all
the predicates are true.
```
svfloat64_t test(svfloat64_t a, svfloat64_t b)
{
return svadd_m(svptrue_b64(), a, b);
}
```
but gcc instead generates an all-tree predicate and use that instead, i.e.
```
ptrue p0.b, all
fadd z0.d, p0/m, z0.d, z1.d
```
The same happens for the `_z` version as well with even worse code generated.
```
ptrue p0.b, all
movprfx z0.d, p0/z, z0.d
fadd z0.d, p0/m, z0.d, z1.d
```
This optimization is only done for the `_x` variance. Clang optimizes this for
all variance.
