On Wed, Aug 23, 2023 at 08:03:58AM +0000, Jiang, Haochen wrote:
> We could first work on -mevex512 then further discuss -mavx10.1-256/512 since
> these -mavx10.1-256/512 is quite controversial.
>
> Just to clarify, -mno-evex512 -mavx512f should not enable 512 bit vector
> right?
I think it should enable them because -mavx512f is after it. But it seems the
option handling is more complex than I thought, e.g. -mavx512bw -mno-avx512bw
just cancels each other, rather than
enabling AVX512BW, AVX512F, AVX2 and all its dependencies (like -mavx512bw
alone does) and then just disabling AVX512BW (like -mno-avx512bw does).
But, if one uses separate target pragmas, it behaves like that:
#pragma GCC target ("avx512bw")
#ifdef __AVX512F__
int a;
#endif
#ifdef __AVX512BW__
int b;
#endif
#pragma GCC target ("no-avx512bw")
#ifdef __AVX512F__
int c;
#endif
#ifdef __AVX512BW__
int d;
#endif
The above defines a, b and c vars even without any special -march= or other
command line option.
So, first important decision would be whether to make EVEX512
OPTION_MASK_ISA_EVEX512 or OPTION_MASK_ISA2_EVEX512, the former would need
to move some other ISA flag from the first to second set.
That OPTION_MASK_ISA*_EVEX512 then should be added to
OPTION_MASK_ISA_AVX512F_SET or OPTION_MASK_ISA2_AVX512F_SET (but, if it is
the latter, we also need to do that for tons of other AVX512*_SET),
and then just arrange for -mavx10.1-256 to enable
OPTION_MASK_ISA*_AVX512*_SET of everything it needs except the EVEX512 set
(but, only disable it from the newly added set, not actually act as
-mavx512{f,bw,...} -mno-evex512).
OPTION_MASK_ISA*_EVEX512_SET dunno, should it enable OPTION_MASK_ISA_AVX512F
or just EVEX512?
And then the UNSET cases...
Jakub
