From f51be2fb8653f81092f8158a0f0527275f86603b Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 23 Apr 2020 21:57:50 +0200 Subject: [PATCH] Shortcut identity VEC_PERM expansion [PR94710] This PR is about the rs6000 backend emitting wrong assembly for whole vector shift by 0, and while I think it is desirable to fix the backend, I don't see a point why the expander should try to emit that, whole vector shift by 0 is identity, we can just return the operand. 2020-04-23 Jakub Jelinek PR target/94710 * optabs.c (expand_vec_perm_const): For shift_amt const0_rtx just return v2. --- gcc/ChangeLog | 4 ++++ gcc/optabs.c | 2 ++ 2 files changed, 6 insertions(+) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 5ddb4332047..54e207cbe58 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,9 @@ 2020-04-23 Jakub Jelinek + PR target/94710 + * optabs.c (expand_vec_perm_const): For shift_amt const0_rtx + just return v2. + PR middle-end/94724 * tree.c (get_narrower): Instead of creating COMPOUND_EXPRs temporarily with non-final second operand and updating it later, diff --git a/gcc/optabs.c b/gcc/optabs.c index 1456e59ffa7..d85ce47f762 100644 --- a/gcc/optabs.c +++ b/gcc/optabs.c @@ -5627,6 +5627,8 @@ expand_vec_perm_const (machine_mode mode, rtx v0, rtx v1, if (shift_amt) { class expand_operand ops[3]; + if (shift_amt == const0_rtx) + return v2; if (shift_code != CODE_FOR_nothing) { create_output_operand (&ops[0], target, mode); -- 2.30.2