public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "vries at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/67955] New: tree-dse does not use pointer info Date: Tue, 13 Oct 2015 13:57:00 -0000 [thread overview] Message-ID: <bug-67955-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67955 Bug ID: 67955 Summary: tree-dse does not use pointer info Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: vries at gcc dot gnu.org Target Milestone: --- Consider this testcase, with dead store '*p = 1': ... int f () { int a; int *p = &a; *p = 1; a = 2; return a; } ... We compile with -O2 -fno-tree-ccp -fno-tree-forwprop -fno-tree-fre. At dse1 we have ... f () { int * p; int a; int _5; <bb 2>: p_1 = &a; *p_1 = 1; a = 2; _5 = a; a ={v} {CLOBBER}; return _5; } ... So, the dead store '*p_1 = 1' has not been eliminated. However, at ealias we already know: ... Alias information for f Aliased symbols a, UID D.1757, int, is addressable Call clobber information ESCAPED, points-to non-local, points-to vars: { } Flow-insensitive points-to information p_1, points-to vars: { D.1757 } ... So, we could use points-to info in dce.
next reply other threads:[~2015-10-13 13:57 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-10-13 13:57 vries at gcc dot gnu.org [this message] 2015-10-13 14:25 ` [Bug tree-optimization/67955] " rguenth at gcc dot gnu.org 2015-10-13 15:34 ` vries at gcc dot gnu.org 2015-10-14 7:28 ` rguenth at gcc dot gnu.org 2015-10-14 11:06 ` vries at gcc dot gnu.org 2015-10-14 12:18 ` vries at gcc dot gnu.org 2015-10-14 14:56 ` vries at gcc dot gnu.org 2015-10-15 6:32 ` vries at gcc dot gnu.org 2015-10-15 6:32 ` vries 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-67955-4@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).