public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "hubicka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/110377] New: Early VRP and IPA-PROP should work out value ranges from __builtin_unreacahble Date: Fri, 23 Jun 2023 15:37:29 +0000 [thread overview] Message-ID: <bug-110377-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110377 Bug ID: 110377 Summary: Early VRP and IPA-PROP should work out value ranges from __builtin_unreacahble Product: gcc Version: 13.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: middle-end Assignee: unassigned at gcc dot gnu.org Reporter: hubicka at gcc dot gnu.org Target Milestone: --- In the following testcase void test2(int); void test(int n) { if (n > 5) __builtin_unreachable (); test2(n); } we should work out that value range of n passed to test2 is [INT_MIN,4]. This would help optimizing some code in libstdc++, which now uses similar constructs to ensure known value ranges. I think it is a common case where such unreachable test can be retrofited to the SSA_NAME based on the fact that program can not terminate between definition and the conditional. We currently get: function test/0 parameter descriptors: param #0 n used undescribed_use Jump functions of caller test/0: callsite test/0 -> test2/2 : param 0: PASS THROUGH: 0, op nop_expr value: 0x0, mask: 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff Unknown VR callsite test/0 -> __builtin_unreachable/1 :
next reply other threads:[~2023-06-23 15:37 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-23 15:37 hubicka at gcc dot gnu.org [this message] 2023-06-26 8:56 ` [Bug middle-end/110377] Early VRP and IPA-PROP should work out value ranges from __builtin_unreachable rguenth at gcc dot gnu.org 2023-06-26 14:20 ` amacleod at redhat dot com 2023-06-26 16:48 ` hubicka at gcc dot gnu.org 2023-06-26 19:49 ` amacleod at redhat dot com 2023-06-27 7:45 ` hubicka at gcc dot gnu.org 2023-06-28 7:35 ` cvs-commit at gcc dot gnu.org 2023-11-21 15:12 ` hubicka 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-110377-4@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).