On Tue, Aug 22, 2023 at 09:35:44PM +0800, Hongtao Liu wrote:
> Ok, then we can't avoid TARGET_AVX10_1 in those existing 256/128-bit
> evex instruction patterns.
Why?
Internally for md etc. purposes, we should have the current
TARGET_AVX512* etc. ISA flags, plus one new one, whatever we call it
(TARGET_EVEX512 even if it is not completely descriptive because of kandq
etc., or some other name) which says if 512-bit vector modes can be used,
if g modifier can be used, if the 64-bit mask operations can be used etc.
Plus, if AVX10.1 contains any instructions not covered in the preexisting
TARGET_AVX512* sets, TARGET_AVX10_1 which covers that delta, otherwise
keep -mavx10.1 just as an command line option which enables/disables
other stuff.
The current common/config/i386/i386-common.cc OPTION_MASK_ISA*SET* would be
like now, except that the current AVX512* sets imply also EVEX512/whatever
it will be called, that option itself enables nothing (or TARGET_AVX512F),
and unsetting it doesn't disable all the TARGET_AVX512*.
-mavx10.1 would enable the AVX512* sets without EVEX512/whatever.
At the end of the option processing, if EVEX512/whatever is set but
TARGET_AVX512VL is not, disable TARGET_AVX512F with all its dependencies,
because VL is a precondition of 128/256-bit EVEX and if 512-bit EVEX is not
enabled, there is nothing left.
Jakub
