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* [Bug tree-optimization/67998] New: redundant test for 0 when also checking inequality
@ 2015-10-16 21:31 rv at rasmusvillemoes dot dk
2021-06-03 4:14 ` [Bug tree-optimization/67998] " pinskia at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: rv at rasmusvillemoes dot dk @ 2015-10-16 21:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67998
Bug ID: 67998
Summary: redundant test for 0 when also checking inequality
Product: gcc
Version: 5.1.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rv at rasmusvillemoes dot dk
Target Milestone: ---
int f(unsigned a, unsigned b)
{
if (!a || b >= a)
return 5;
return 2;
}
compiles to
f(unsigned int, unsigned int):
testl %edi, %edi
je .L3
cmpl %esi, %edi
jbe .L3
movl $2, %eax
ret
.L3:
movl $5, %eax
ret
The first test is redundant, since if a is zero, the inequality is guaranteed
to hold.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug tree-optimization/67998] redundant test for 0 when also checking inequality
2015-10-16 21:31 [Bug tree-optimization/67998] New: redundant test for 0 when also checking inequality rv at rasmusvillemoes dot dk
@ 2021-06-03 4:14 ` pinskia at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-06-03 4:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67998
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|NEW |RESOLVED
Target Milestone|--- |12.0
Known to fail| |7.1.0
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed already on the trunk, I have not tried any other version (except GCC 7
where it was still broken):
<bb 2> [local count: 1073741824]:
if (a_2(D) <= b_3(D))
goto <bb 3>; [34.00%]
else
goto <bb 4>; [66.00%]
<bb 3> [local count: 365072224]:
<bb 4> [local count: 1073741824]:
# _1 = PHI <5(3), 2(2)>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2015-10-16 21:31 [Bug tree-optimization/67998] New: redundant test for 0 when also checking inequality rv at rasmusvillemoes dot dk
2021-06-03 4:14 ` [Bug tree-optimization/67998] " pinskia at gcc dot gnu.org
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