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From: "felix.von.s at posteo dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/95810] New: Spurious UBSan warning when
 computing the opposite of the absolute value of INT_MIN
Date: Mon, 22 Jun 2020 07:52:41 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 11.0
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X-Bugzilla-Who: felix.von.s at posteo dot de
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95810

            Bug ID: 95810
           Summary: Spurious UBSan warning when computing the opposite of
                    the absolute value of INT_MIN
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: felix.von.s at posteo dot de
  Target Milestone: ---

When the expression (x <=3D 0 ? x : -x) with x having type int is compiled =
with
-fsanitize=3Dundefined -O3, setting (x =3D INT_MIN) triggers a spurious UBS=
an
warning about INT_MIN being negated.

Not sure if I should file this against tree-ssa or the frontend(s), because=
 the
expression apparently becomes (-ABS_EXPR <x>) very early, even at -O0. I
checked this with C, C++ and D frontends.=