public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "rjiejie at me dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/97170] New: Wrong optimization in fwprop pass Date: Wed, 23 Sep 2020 05:36:38 +0000 [thread overview] Message-ID: <bug-97170-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97170 Bug ID: 97170 Summary: Wrong optimization in fwprop pass Product: gcc Version: 8.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization Assignee: unassigned at gcc dot gnu.org Reporter: rjiejie at me dot com Target Milestone: --- insn seqs: s1: __builtin_set_float_convert_mode(0); r1 = __builtin_load(a1, a2); r2 = __builtin_float_convert(r1); __builtin_store(a3, r2); __builtin_set_float_convert_mode(0); s2: __builtin_set_float_convert_mode(1); r1 = __builtin_load(a1, a2); r2 = __builtin_float_convert(r1); __builtin_store(a3, r2); __builtin_set_float_convert_mode(0); the diference of s1 and s2 only is "__builtin_set_float_convert_mode" from beginning, the s1 mode is set 0, but s2 mode is set 1. from optimization 'fwprop', the s2 insns seqs is deleted as dead code, is it gcc bug ? builtin patten of __builtin_set_float_convert_mode: (define_insn "target_fcvtmode" [(set (reg:SI FCVTMODE_REGNUM) (unspec_volatile:SI [(match_operand:SI 0 "csr_operand" "rK")] UNSPECV_FCVTMODE))] "" "fcvtmode\t%1" ) builtin patten of __builtin_set_float_convert_mode: (define_insn "target_fcvt" [(set (match_operand:SI 0 "register_operand" "=r") (unspec:SI [(match_operand:SF 1 "register_operand" "f")] UNSPEC_FCVT)) (use (reg:SI FCVTMODE_REGNUM))] "" "fcvt\t%0,%1" ) As far as i know, __builtin_set_float_convert_mode depend on 'FCVTMODE_REGNUM' which is from __builtin_set_float_convert_mode, it's not dead code. or something wrong in my pattens ? Anyone could give me some hints ? Thanks
next reply other threads:[~2020-09-23 5:36 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-23 5:36 rjiejie at me dot com [this message] 2020-09-23 5:49 ` [Bug rtl-optimization/97170] " pinskia at gcc dot gnu.org 2020-09-23 8:08 ` rjiejie at me 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-97170-4@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).