public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/105136] [11/12 regression] Missed optimization regression with 32-bit adds and shifts Date: Mon, 04 Apr 2022 08:53:44 +0000 [thread overview] Message-ID: <bug-105136-4-GPHVlmWmVd@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-105136-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105136 --- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> --- The regression in bar: is due to RA regression for: (insn 28 27 29 2 (parallel [ (set (reg:SI 89) (plus:SI (reg:SI 92) (subreg:SI (reg:DI 87) 0))) (clobber (reg:CC 17 flags)) ]) "pr105136.c":4:11 229 {*addsi_1} (expr_list:REG_DEAD (reg:SI 92) (expr_list:REG_UNUSED (reg:CC 17 flags) (nil)))) gcc-10.3 allocates: (insn 28 27 29 2 (parallel [ (set (reg:SI 0 ax [89]) (plus:SI (reg:SI 4 si [92]) (reg:SI 5 di [87]))) (clobber (reg:CC 17 flags)) ]) "pr105136.c":4:11 185 {*addsi_1} (nil)) while gcc-12 allocates: (insn 28 27 29 2 (parallel [ (set (reg:SI 4 si [89]) (plus:SI (reg:SI 4 si [92]) (reg:SI 5 di [87]))) (clobber (reg:CC 17 flags)) ]) "pr105136.c":4:11 229 {*addsi_1} (nil)) (...) and reloads the output to ax: (insn 35 29 30 2 (set (reg:SI 0 ax [89]) (reg:SI 4 si [89])) "pr105136.c":4:11 81 {*movsi_internal} (nil)) (insn 30 35 20 2 (set (reg:SI 0 ax [89]) (if_then_else:SI (eq (reg:CCZ 17 flags) (const_int 0 [0])) (reg:SI 5 di [87]) (reg:SI 0 ax [89]))) "pr105136.c":4:11 1201 {*movsicc_noc} (nil)) The pattern allows r/r/r in alternative 3, so the question is why RA doesn't consider it: (define_insn "*add<mode>_1" [(set (match_operand:SWI48 0 "nonimmediate_operand" "=rm,r,r,r") (plus:SWI48 (match_operand:SWI48 1 "nonimmediate_operand" "%0,0,r,r") (match_operand:SWI48 2 "x86_64_general_operand" "re,BM,0,le"))) (clobber (reg:CC FLAGS_REG))] The "l" constraint is user defined register constraint: (define_register_constraint "l" "INDEX_REGS" "@internal Any register that can be used as the index in a base+index memory access: that is, any general register except the stack pointer.") so perhaps user defined constraint deters RA from using this alternative.
next prev parent reply other threads:[~2022-04-04 8:53 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-02 13:55 [Bug middle-end/105136] New: [11/12] " andre.schackier at gmail dot com 2022-04-04 7:19 ` [Bug target/105136] [11/12 regression] " rguenth at gcc dot gnu.org 2022-04-04 8:53 ` ubizjak at gmail dot com [this message] 2022-04-19 18:08 ` jakub at gcc dot gnu.org 2022-04-20 15:48 ` vmakarov at gcc dot gnu.org 2022-04-21 7:51 ` rguenth at gcc dot gnu.org 2023-05-29 10:06 ` [Bug target/105136] [11/12/13/14 " jakub 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-105136-4-GPHVlmWmVd@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).