https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94866
--- Comment #4 from Uroš Bizjak <ubizjak at gmail dot com> --- (In reply to Hongtao.liu from comment #3) > in x86 backend expand_vec_perm_1, we always tries vec_merge frist for > !one_operand_p, expand_vselect_vconcat is only tried when vec_merge failed > which means we'd better to use vec_merge instead of vec_select:vec_concat > when available in out backend pattern match. In fact, I tried to convert existing sse2_movq128 patterns to vec_merge, but the patch regressed: -FAIL: gcc.target/i386/sse2-pr94680-2.c scan-assembler movq -FAIL: gcc.target/i386/sse2-pr94680-2.c scan-assembler-not pxor -FAIL: gcc.target/i386/sse2-pr94680.c scan-assembler-not pxor -FAIL: gcc.target/i386/sse2-pr94680.c scan-assembler-times (?n)(?:mov|psrldq).*%xmm[0-9] 12 So, the compiler still expects vec_concat/vec_select patterns to be present.
