public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "ktkachov at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/98581] New: unexpected reassociation for umin/umax ? Date: Thu, 07 Jan 2021 12:52:05 +0000 [thread overview] Message-ID: <bug-98581-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98581 Bug ID: 98581 Summary: unexpected reassociation for umin/umax ? Product: gcc Version: unknown Status: UNCONFIRMED Keywords: missed-optimization Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: ktkachov at gcc dot gnu.org Target Milestone: --- typedef signed int *__restrict__ pSINT; typedef unsigned int *__restrict__ pUINT; #define MIN(a, b) ((a) < (b) ? (a) : (b)) #define MAX(a, b) ((a) > (b) ? (a) : (b)) void saba_s (pSINT a, pSINT b, pSINT c) { int i; for (i = 0; i < 4; i++) c[i] += (MAX (a[i], b[i]) - MIN (a[i], b[i])); } void saba_u (pUINT a, pUINT b, pUINT c) { int i; for (i = 0; i < 4; i++) c[i] += (MAX (a[i], b[i]) - MIN (a[i], b[i])); } On aarch64 at -O3 generates: saba_s: ldr q0, [x0] ldr q1, [x1] ldr q2, [x2] sabd v0.4s, v0.4s, v1.4s add v0.4s, v0.4s, v2.4s str q0, [x2] ret saba_u: ldr q1, [x0] ldr q2, [x1] ldr q3, [x2] umax v0.4s, v1.4s, v2.4s umin v1.4s, v1.4s, v2.4s add v0.4s, v0.4s, v3.4s sub v0.4s, v0.4s, v1.4s str q0, [x2] ret I would expect the (MAX (a[i], b[i]) - MIN (a[i], b[i])) part to match a uabd instruction for the unsigned case, but it looks like the add and sub operations are swapped which prevents the RTL pattern matching the operation. This comes out this way out of GIMPLE. At expand the signed version is: vect__4.6_40 = MEM <vector(4) int> [(int *)c_16(D)]; vect__6.9_37 = MEM <vector(4) int> [(int *)b_17(D)]; vect__8.12_34 = MEM <vector(4) int> [(int *)a_18(D)]; vect__9.13_33 = MAX_EXPR <vect__8.12_34, vect__6.9_37>; vect__10.14_32 = MIN_EXPR <vect__8.12_34, vect__6.9_37>; vect__11.15_31 = vect__9.13_33 - vect__10.14_32; vect__12.16_30 = vect__11.15_31 + vect__4.6_40; MEM <vector(4) int> [(int *)c_16(D)] = vect__12.16_30; return; the unsigned is: vect__4.25_38 = MEM <vector(4) unsigned int> [(unsigned int *)c_16(D)]; vect__6.28_35 = MEM <vector(4) unsigned int> [(unsigned int *)b_17(D)]; vect__8.31_32 = MEM <vector(4) unsigned int> [(unsigned int *)a_18(D)]; vect__9.32_31 = MAX_EXPR <vect__8.31_32, vect__6.28_35>; vect__10.33_30 = MIN_EXPR <vect__8.31_32, vect__6.28_35>; vect__13.34_29 = vect__9.32_31 + vect__4.25_38; vect__12.35_28 = vect__13.34_29 - vect__10.33_30; MEM <vector(4) unsigned int> [(unsigned int *)c_16(D)] = vect__12.35_28; return;
next reply other threads:[~2021-01-07 12:52 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-07 12:52 ktkachov at gcc dot gnu.org [this message] 2021-01-07 13:31 ` [Bug tree-optimization/98581] " rguenth at gcc dot gnu.org 2023-05-02 1:19 ` pinskia at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-98581-4@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).