https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125949
--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-15 branch has been updated by Venkataramanan Kumar <[email protected]>: https://gcc.gnu.org/g:bc94d524c45a56e8fb98de9b2ed7f64d26cb54ac commit r15-11485-gbc94d524c45a56e8fb98de9b2ed7f64d26cb54ac Author: vekumar <[email protected]> Date: Thu Jun 25 10:33:55 2026 +0530 i386: Restrict AVX-VNNI-INT8 insns to VEX encoding [PR125949] The vpdpb{ss,su,uu}d[s] instructions from AVX-VNNI-INT8 only have a VEX encoding; the EVEX form of these operations is provided by AVX10.2. A target such as -march=znver6 enables AVX-VNNI-INT8 together with the AVX-512 xmm/ymm16-31 register file but does not have AVX10.2. The vpdp<vpdotprodtype>_<mode> pattern used a single "v" alternative with a "maybe_evex" prefix, so under register pressure the allocator could pick xmm/ymm16-31 and the instruction was promoted to its EVEX form, which is not available on such targets. Add a VEX-only alternative that keeps the operands in xmm/ymm0-15 (enabled for AVX-VNNI-INT8) and gate the existing EVEX alternative on AVX10.2. When AVX10.2 is not available only the VEX alternative is enabled, so the high registers are no longer used and the EVEX form is never emitted. gcc/ChangeLog: PR target/125949 * config/i386/i386.md ("isa"): Add avxvnniint8. ("enabled"): Adjust for avxvnniint8. * config/i386/sse.md (vpdp<vpdotprodtype>_<mode>): Adjust for AVXVNNIINT8. gcc/testsuite/ChangeLog: PR target/125949 * gcc.target/i386/pr125949.c: New test. (cherry picked from commit 314bd1495ca78f5934f83a4dbc6028dd34fb0652)
