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* [Bug target/113857] New: fmov should be used to zero the upper bits of the vector register
@ 2024-02-09 23:37 pinskia at gcc dot gnu.org
2024-02-09 23:41 ` [Bug target/113857] " pinskia at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-02-09 23:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113857
Bug ID: 113857
Summary: fmov should be used to zero the upper bits of the
vector register
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Target: aarch64
Take:
```
#define vect128 __attribute__((vector_size(16) ))
#define vect64 __attribute__((vector_size(8) ))
vect64 float f64( float a)
{
return (vect64 float){a, 0};
}
vect128 float f128( float a)
{
return (vect128 float){a, 0, 0, 0};
}
```
GCC produces fmov for f64 but does not for f128.
Note we could the same for:
```
vect64 short s64( short a)
{
return (vect64 short){a, 0};
}
vect128 int i128( int a)
{
return (vect128 int){a, 0};
}
```
Well s64 can only be done if f16 extensions are enabled.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug target/113857] fmov should be used to zero the upper bits of the vector register
2024-02-09 23:37 [Bug target/113857] New: fmov should be used to zero the upper bits of the vector register pinskia at gcc dot gnu.org
@ 2024-02-09 23:41 ` pinskia at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-02-09 23:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113857
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Without f16 extension, s64 could be done as:
```
and x0, x0, 0xffff
fmov s0, x0
```
Similarly if we are doing a `c64` .
^ permalink raw reply [flat|nested] 2+ messages in thread
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2024-02-09 23:37 [Bug target/113857] New: fmov should be used to zero the upper bits of the vector register pinskia at gcc dot gnu.org
2024-02-09 23:41 ` [Bug target/113857] " pinskia at gcc dot gnu.org
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