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From: "law at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111472] [11/12/13 Regression] Wrong code at
 -Os on x86_64-linux-gnu since r11-4563-gd0d8b5d836
Date: Thu, 07 Mar 2024 22:24:15 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111472

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at gcc dot gnu.org
            Summary|[11/12/13/14 Regression]    |[11/12/13 Regression] Wrong
                   |Wrong code at -Os on        |code at -Os on
                   |x86_64-linux-gnu since      |x86_64-linux-gnu since
                   |r11-4563-gd0d8b5d836        |r11-4563-gd0d8b5d836

--- Comment #6 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Close.  It was the next revision my bisection landed on as the fix:

commit 9692309ed6b625f0fb358c0e230404b5603f69a6 (refs/bisect/bad)
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Oct 20 15:08:49 2023 +0200

    tree-optimization/111445 - simple_iv simplification fault

    The following fixes a missed check in the simple_iv attempt
    to simplify (signed T)((unsigned T) base + step) where it
    allows a truncating inner conversion leading to wrong code.

            PR tree-optimization/111445
            * tree-scalar-evolution.cc (simple_iv_with_niters):
            Add missing check for a sign-conversion.

            * gcc.dg/torture/pr111445.c: New testcase.=