public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "theodort at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/102880] New: [12 Regression] Dead Code Elimination Regression at -O3 Date: Thu, 21 Oct 2021 13:27:42 +0000 [thread overview] Message-ID: <bug-102880-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102880 Bug ID: 102880 Summary: [12 Regression] Dead Code Elimination Regression at -O3 Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: theodort at inf dot ethz.ch Target Milestone: --- cat test.c void foo(void); static int b, c, d, e, f, ah; static short g, ai, am, aq, as; static char an, at, av, ax, ay; static char a(char h, char i) { return i == 0 || h && i == 1 ? 0 : h % i; } static void ae(int h) { if (a(b, h)) foo(); } int main() { ae(1); ay = a(0, ay); ax = a(g, aq); at = a(0, as); av = a(c, 1); an = a(am, f); int al = e || ((a(1, ah) && b) & d) == 2; ai = al; } 11.2.0 at -O3 can eliminate the call to foo but trunk at -O3 cannot: gcc-11 -O3 -S test.c -o /dev/stdout ... main: .LFB2: .cfi_startproc movb $0, ay(%rip) xorl %eax, %eax ret .cfi_endproc gcc-11 -O3 -S test.c -o /dev/stdout ... a.part.0: .LFB3: .cfi_startproc testb %dil, %dil je .L5 xorl %eax, %eax cmpb $1, %sil jne .L5 ret .L5: movsbl %dil, %eax movsbl %sil, %esi cltd idivl %esi movl %edx, %eax ret .cfi_endproc ... main: .LFB2: .cfi_startproc subq $8, %rsp .cfi_def_cfa_offset 16 xorl %edi, %edi movl $1, %esi call a.part.0 testb %al, %al jne .L18 .L9: movzbl ay(%rip), %eax testb %al, %al je .L10 movsbl %al, %esi xorl %edi, %edi call a.part.0 .L10: movb %al, ay(%rip) xorl %eax, %eax addq $8, %rsp .cfi_remember_state .cfi_def_cfa_offset 8 ret .L18: .cfi_restore_state call foo jmp .L9 .cfi_endproc gcc-trunk -v Using built-in specs. Target: x86_64-pc-linux-gnu Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 12.0.0 20211021 (experimental) (GCC) Started with https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b58dc0b803057c0e6032e0d9bd92cd834f72c75c
next reply other threads:[~2021-10-21 13:27 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-21 13:27 theodort at inf dot ethz.ch [this message] 2021-10-21 13:46 ` [Bug tree-optimization/102880] " marxin at gcc dot gnu.org 2021-10-22 6:56 ` pinskia at gcc dot gnu.org 2021-10-22 6:57 ` rguenth at gcc dot gnu.org 2021-10-22 8:44 ` rguenth at gcc dot gnu.org 2021-10-29 9:09 ` rguenth at gcc dot gnu.org 2021-11-11 12:42 ` rguenth at gcc dot gnu.org 2021-11-16 10:31 ` cvs-commit at gcc dot gnu.org 2021-11-16 10:32 ` cvs-commit at gcc dot gnu.org 2021-11-16 10:33 ` rguenth at gcc dot gnu.org 2021-11-17 8:41 ` clyon at gcc dot gnu.org 2021-11-17 8:47 ` pinskia at gcc dot gnu.org 2021-11-18 8:56 ` rguenth 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-102880-4@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).