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/110080] [13/14 Regression] Missed Dead Code Elimination at -Os when using __builtin_unreachable since r13-6945-g429a7a88438 Date: Thu, 01 Jun 2023 14:02:32 +0000 [thread overview] Message-ID: <bug-110080-4-0wb5pekQAN@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-110080-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110080 --- Comment #1 from Theodoros Theodoridis <theodort at inf dot ethz.ch> --- Oops, the first code snippet is wrong in the original post: void foo(void); static unsigned char a = 131; static int *b; static int **c = &b; static void d(int e, unsigned f) { int *g; if (!e){ // <------------------------ if (!e) is correct for (; a; ++a) for (e = 0; 0;) ; g = &e; int **h = &g; if (**h) { foo(); } } *c = &e; } int main() { d(4 & a, a); } this is also the correct assembly for gcc trunk/13.1/12.3 at -Os: main: movb a(%rip), %al testb $4, %al jne .L5 xorl %edx, %edx .L2: testb %al, %al je .L12 incl %eax movb $1, %dl jmp .L2 .L12: testb %dl, %dl je .L5 movb $0, a(%rip) .L5: leaq -4(%rsp), %rax movq %rax, b(%rip) xorl %eax, %eax ret a: .byte -125 the code with the _builtin_unreachable and the rest are correct
next prev parent reply other threads:[~2023-06-01 14:02 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-01 13:54 [Bug tree-optimization/110080] New: " theodort at inf dot ethz.ch 2023-06-01 14:02 ` theodort at inf dot ethz.ch [this message] 2023-06-02 7:53 ` [Bug tree-optimization/110080] " rguenth at gcc dot gnu.org 2023-07-27 9:26 ` rguenth at gcc dot gnu.org 2023-08-21 23:20 ` pinskia at gcc dot gnu.org 2023-08-21 23:21 ` pinskia at gcc dot gnu.org 2023-09-19 14:30 ` cvs-commit at gcc dot gnu.org 2023-09-19 15:03 ` amacleod at redhat dot com
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-110080-4-0wb5pekQAN@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).