https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121606
--- Comment #10 from rguenther at suse dot de <rguenther at suse dot de> --- On Wed, 20 Aug 2025, haochen.jiang at intel dot com wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121606 > > --- Comment #8 from Haochen Jiang <haochen.jiang at intel dot com> --- > (In reply to Haochen Jiang from comment #6) > > (In reply to rguent...@suse.de from comment #5) > > > > > > doesn't diagnose it. And I wouldn't have expected a diagnostic for this > > > as -mavx10.1 should simply re-enable avx512fp16? > > > > Hmm you are right here. Let me have a look on that. > > Correction here, it should be expected a warning here for GCC15 since it is > not > a simple re-enable at that time where we still take them as separate features. > > Trunk should w/o that warning. Ah yes, I tested trunk. On the branch indeed I see > ../../gcc15-g/gcc/cc1 -quiet t.c -mno-avx512fp16 -mavx10.1 cc1: warning: ‘-mavx10.1’ is aliased to 512 bit since GCC14.3 and GCC15.1 while ‘-mavx10.1-256’ and ‘-mavx10.1-512’ will be deprecated in GCC 16 due to all machines 512 bit vector size supported cc1: warning: ‘-mno-evex512’ or ‘-mno-avx512XXX’ cannot disable AVX10 instructions when AVX10.1-512 is available in GCC 15, behavior will change to it will disable that part of AVX512 instructions since GCC 16 and > ../../gcc15-g/gcc/cc1 -quiet t.c -mavx10.1 cc1: warning: ‘-mavx10.1’ is aliased to 512 bit since GCC14.3 and GCC15.1 while ‘-mavx10.1-256’ and ‘-mavx10.1-512’ will be deprecated in GCC 16 due to all machines 512 bit vector size supported I wonder how at least the warning about using -mavx10.1 makes sense given it says it enables 512bits which is the same behavior as in GCC 16? The same diagnostic is in -mavx10.1-256 which is even more confusing? I belive we should make -mavx10.1-512 not an Alias and put the diagnostic there, not on -mavx10.1 uses? For the diagnostic about -mno-evex512 the confusing thing is that this option wasn't specified. The behavior of -mno-avx512fp16 shouldn't change, and specifically adding -mavx10.1 (_not_ -mavx10.1-256) should simply re-enable it. With -mno-avx512fp16 -mavx10.1-256 it should, in 15, re-enable only the 256 bit part of avx512fp16 obviously.
