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* [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN
@ 2020-06-22 7:52 felix.von.s at posteo dot de
2020-06-22 8:51 ` [Bug middle-end/95810] " pinskia at gcc dot gnu.org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: felix.von.s at posteo dot de @ 2020-06-22 7:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95810
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 <= 0 ? x : -x) with x having type int is compiled with
-fsanitize=undefined -O3, setting (x = INT_MIN) triggers a spurious UBSan
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.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/95810] Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN
2020-06-22 7:52 [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN felix.von.s at posteo dot de
@ 2020-06-22 8:51 ` pinskia at gcc dot gnu.org
2020-06-22 9:36 ` jakub at gcc dot gnu.org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu.org @ 2020-06-22 8:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95810
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|tree-optimization |middle-end
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
It should have became uabs instead.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/95810] Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN
2020-06-22 7:52 [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN felix.von.s at posteo dot de
2020-06-22 8:51 ` [Bug middle-end/95810] " pinskia at gcc dot gnu.org
@ 2020-06-22 9:36 ` jakub at gcc dot gnu.org
2020-06-22 9:53 ` jakub at gcc dot gnu.org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: jakub at gcc dot gnu.org @ 2020-06-22 9:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95810
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org
Last reconfirmed| |2020-06-22
CC| |jakub at gcc dot gnu.org
Status|UNCONFIRMED |ASSIGNED
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/95810] Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN
2020-06-22 7:52 [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN felix.von.s at posteo dot de
2020-06-22 8:51 ` [Bug middle-end/95810] " pinskia at gcc dot gnu.org
2020-06-22 9:36 ` jakub at gcc dot gnu.org
@ 2020-06-22 9:53 ` jakub at gcc dot gnu.org
2020-06-24 8:41 ` cvs-commit at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: jakub at gcc dot gnu.org @ 2020-06-22 9:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95810
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 48769
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48769&action=edit
gcc11-pr95810.patch
Untested fix.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/95810] Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN
2020-06-22 7:52 [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN felix.von.s at posteo dot de
` (2 preceding siblings ...)
2020-06-22 9:53 ` jakub at gcc dot gnu.org
@ 2020-06-24 8:41 ` cvs-commit at gcc dot gnu.org
2020-09-16 19:22 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-06-24 8:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95810
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:01e10b0ee77e82cb331414c569e02dc7a2c4999e
commit r11-1620-g01e10b0ee77e82cb331414c569e02dc7a2c4999e
Author: Jakub Jelinek <jakub@redhat.com>
Date: Wed Jun 24 10:40:02 2020 +0200
fold-const: Fix A <= 0 ? A : -A folding [PR95810]
We folded A <= 0 ? A : -A into -ABS (A), which is for signed integral types
incorrect - can invoke on INT_MIN UB twice, once on ABS and once on its
negation.
The following patch fixes it by instead folding it to (type)-ABSU (A).
2020-06-24 Jakub Jelinek <jakub@redhat.com>
PR middle-end/95810
* fold-const.c (fold_cond_expr_with_comparison): Optimize
A <= 0 ? A : -A into (type)-absu(A) rather than -abs(A).
* gcc.dg/ubsan/pr95810.c: New test.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/95810] Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN
2020-06-22 7:52 [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN felix.von.s at posteo dot de
` (3 preceding siblings ...)
2020-06-24 8:41 ` cvs-commit at gcc dot gnu.org
@ 2020-09-16 19:22 ` cvs-commit at gcc dot gnu.org
2021-04-28 17:56 ` [Bug middle-end/95810] [8 only] " pinskia at gcc dot gnu.org
2021-05-14 14:02 ` jakub at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-09-16 19:22 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95810
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:6ff6c02695c9b6ae6e840422080f6d10449577b8
commit r9-8901-g6ff6c02695c9b6ae6e840422080f6d10449577b8
Author: Jakub Jelinek <jakub@redhat.com>
Date: Wed Jun 24 10:40:02 2020 +0200
fold-const: Fix A <= 0 ? A : -A folding [PR95810]
We folded A <= 0 ? A : -A into -ABS (A), which is for signed integral types
incorrect - can invoke on INT_MIN UB twice, once on ABS and once on its
negation.
The following patch fixes it by instead folding it to (type)-ABSU (A).
2020-06-24 Jakub Jelinek <jakub@redhat.com>
PR middle-end/95810
* fold-const.c (fold_cond_expr_with_comparison): Optimize
A <= 0 ? A : -A into (type)-absu(A) rather than -abs(A).
* gcc.dg/ubsan/pr95810.c: New test.
(cherry picked from commit 01e10b0ee77e82cb331414c569e02dc7a2c4999e)
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/95810] [8 only] Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN
2020-06-22 7:52 [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN felix.von.s at posteo dot de
` (4 preceding siblings ...)
2020-09-16 19:22 ` cvs-commit at gcc dot gnu.org
@ 2021-04-28 17:56 ` pinskia at gcc dot gnu.org
2021-05-14 14:02 ` jakub at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-04-28 17:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95810
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |8.5
Summary|Spurious UBSan warning when |[8 only] Spurious UBSan
|computing the opposite of |warning when computing the
|the absolute value of |opposite of the absolute
|INT_MIN |value of INT_MIN
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/95810] [8 only] Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN
2020-06-22 7:52 [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN felix.von.s at posteo dot de
` (5 preceding siblings ...)
2021-04-28 17:56 ` [Bug middle-end/95810] [8 only] " pinskia at gcc dot gnu.org
@ 2021-05-14 14:02 ` jakub at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-05-14 14:02 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95810
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
Target Milestone|8.5 |9.4
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The GCC 8 branch is being closed, fixed in GCC 9.4.
^ permalink raw reply [flat|nested] 8+ messages in thread
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2020-06-22 7:52 [Bug tree-optimization/95810] New: Spurious UBSan warning when computing the opposite of the absolute value of INT_MIN felix.von.s at posteo dot de
2020-06-22 8:51 ` [Bug middle-end/95810] " pinskia at gcc dot gnu.org
2020-06-22 9:36 ` jakub at gcc dot gnu.org
2020-06-22 9:53 ` jakub at gcc dot gnu.org
2020-06-24 8:41 ` cvs-commit at gcc dot gnu.org
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2021-04-28 17:56 ` [Bug middle-end/95810] [8 only] " pinskia at gcc dot gnu.org
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