https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110202
--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Alexander Monakov <amona...@gcc.gnu.org>: https://gcc.gnu.org/g:567d06bb357a39ece865cef67ada44124f227e45 commit r14-2999-g567d06bb357a39ece865cef67ada44124f227e45 Author: Yan Simonaytes <simonaytes....@ispras.ru> Date: Tue Jul 25 20:43:19 2023 +0300 i386: eliminate redundant operands of VPTERNLOG As mentioned in PR 110202, GCC may be presented with input where control word of the VPTERNLOG intrinsic implies that some of its operands do not affect the result. In that case, we can eliminate redundant operands of the instruction by substituting any other operand in their place. This removes false dependencies. For instance, instead of (252 = 0xfc = _MM_TERNLOG_A | _MM_TERNLOG_B) vpternlogq $252, %zmm2, %zmm1, %zmm0 emit vpternlogq $252, %zmm0, %zmm1, %zmm0 When VPTERNLOG is invariant w.r.t first and second operands, and the third operand is memory, load memory into the output operand first, i.e. instead of (85 = 0x55 = ~_MM_TERNLOG_C) vpternlogq $85, (%rdi), %zmm1, %zmm0 emit vmovdqa64 (%rdi), %zmm0 vpternlogq $85, %zmm0, %zmm0, %zmm0 gcc/ChangeLog: PR target/110202 * config/i386/i386-protos.h (vpternlog_redundant_operand_mask): Declare. (substitute_vpternlog_operands): Declare. * config/i386/i386.cc (vpternlog_redundant_operand_mask): New helper. (substitute_vpternlog_operands): New function. Use them... * config/i386/sse.md: ... here in new VPTERNLOG define_splits. gcc/testsuite/ChangeLog: PR target/110202 * gcc.target/i386/invariant-ternlog-1.c: New test. * gcc.target/i386/invariant-ternlog-2.c: New test.
