Hi Richard Thank your for your detailed explanation, I’ll patch the test case with suggestions form LuLu.
Best Levy > On 13 Oct 2022, at 7:12 pm, Richard Biener <richard.guent...@gmail.com> wrote: > > On Thu, Oct 13, 2022 at 10:16 AM Lulu Cheng <chengl...@loongson.cn> wrote: >> >> >>> 在 2022/10/13 下午2:44, Xi Ruoyao 写道: >>> On Thu, 2022-10-13 at 14:15 +0800, Levy wrote: >>>> Hi RuoYao >>>> >>>> It’s probably because loongarch64 doesn’t support >>>> can_vec_perm_const_p(result_mode, op_mode, sel2, false) >>>> >>>> I’m not sure whether if loongarch will support it or should I just >>>> limit the test target for pr54346.c? >>> I'm not sure if we can add TARGET_VECTORIZE_VEC_PERM_CONST when we don't >>> actually support vector. (LoongArch has SIMD instructions but the >>> support in GCC won't be added in a very recent future.) >>> >> If what I understand is correct, I think this might be a better solution. >> >> /* { dg-do compile } */ >> >> +/* { dg-require-effective-target vect_perm } */ >> /* { dg-options "-O -fdump-tree-dse1" } */ > > Btw, what forwprop does is check whether any of the original permutations are > not supported and then elide the supportability check for the result. > The reasoning > is that the original permute(s) would be lowered during vectlower so we can as > well do that for the result. We should just never turn a supported > permutation > sequence into a not supported one. > > Richard. >