https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109900
Bug ID: 109900
Summary: _mm256_abs_epi8 is not expanded on gimple level
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: x86_64-linux-gnu
Take (at -O3 -march=x86-64-v3):
```
#include <immintrin.h>
__m256i
should_be_cmpeq_abs0 ()
{
return _mm256_set1_epi8 (1);
}
__m256i
should_be_cmpeq_abs1 ()
{
return _mm256_abs_epi8(_mm256_set1_epi8 (-1));
}
```
I would have expected these two produce the same code generation.
In the end, we still have a builtin function in the IR rather than ABS_EXPR.
The RTL level uses abs.
In fact combine tries to combine the two instructions:
Trying 5 -> 6:
5: r85:V32QI=const_vector
6: r84:V32QI=abs(r85:V32QI)
REG_DEAD r85:V32QI
REG_EQUAL const_vector
Failed to match this instruction:
(set (reg:V32QI 84)
(const_vector:V32QI [
(const_int 1 [0x1]) repeated x32
]))
