https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114514
--- Comment #5 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by hongtao Liu <liuho...@gcc.gnu.org>: https://gcc.gnu.org/g:090714e6cf8029f4ff8883dce687200024adbaeb commit r15-530-g090714e6cf8029f4ff8883dce687200024adbaeb Author: liuhongt <hongtao....@intel.com> Date: Wed May 15 10:56:24 2024 +0800 Set d.one_operand_p to true when TARGET_SSSE3 in ix86_expand_vecop_qihi_partial. pshufb is available under TARGET_SSSE3, so ix86_expand_vec_perm_const_1 must return true when TARGET_SSSE3. With the patch under -march=x86-64-v2 v8qi foo (v8qi a) { return a >> 5; } < pmovsxbw %xmm0, %xmm0 < psraw $5, %xmm0 < pshufb .LC0(%rip), %xmm0 vs. > movdqa %xmm0, %xmm1 > pcmpeqd %xmm0, %xmm0 > pmovsxbw %xmm1, %xmm1 > psrlw $8, %xmm0 > psraw $5, %xmm1 > pand %xmm1, %xmm0 > packuswb %xmm0, %xmm0 Although there's a memory load from constant pool, but it should be better when it's inside a loop. The load from constant pool can be hoist out. it's 1 instruction vs 4 instructions. < pshufb .LC0(%rip), %xmm0 vs. > pcmpeqd %xmm0, %xmm0 > psrlw $8, %xmm0 > pand %xmm1, %xmm0 > packuswb %xmm0, %xmm0 gcc/ChangeLog: PR target/114514 * config/i386/i386-expand.cc (ix86_expand_vecop_qihi_partial): Set d.one_operand_p to true when TARGET_SSSE3. gcc/testsuite/ChangeLog: * gcc.target/i386/pr114514-shufb.c: New test.
