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From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110582] [14 Regression] Wrong code at -O2/3 on x86_64-linux-gnu
Date: Mon, 31 Jul 2023 16:11:38 +0000	[thread overview]
Message-ID: <bug-110582-4-DdAOlNvDWN@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-110582-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110582

Andrew Macleod <amacleod at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #7 from Andrew Macleod <amacleod at redhat dot com> ---
There was a bug in the implementation of fur_list where it was using the
supplied values for *any* encountered operand, not just ssa_names.   so when
the phi analyzer was trying to find an initial value fro the PHI a_lsm.2_29 it
was miscalculating the value of iftmp.1_15 and thought it had an (incorrect)
limited range of [-2,2].

 # a_lsm.12_29 = PHI <iftmp.1_11(4)>
  iftmp.1_15 = 3 / a_lsm.12_29; 

it then though it could fold away the condition.

The patch adjusts the operand fetcher to work properly, and then the phi
analyzer calcualtes the range for the statement properly, and we can no longer
remove the condtion.

      parent reply	other threads:[~2023-07-31 16:11 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-07  8:03 [Bug c/110582] New: " shaohua.li at inf dot ethz.ch
2023-07-07  8:40 ` [Bug tree-optimization/110582] [14 Regression] " pinskia at gcc dot gnu.org
2023-07-07 11:19 ` rguenth at gcc dot gnu.org
2023-07-08  1:08 ` pinskia at gcc dot gnu.org
2023-07-08  1:17 ` pinskia at gcc dot gnu.org
2023-07-30 14:46 ` shaohua.li at inf dot ethz.ch
2023-07-31 16:06 ` cvs-commit at gcc dot gnu.org
2023-07-31 16:11 ` amacleod at redhat dot com [this message]

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