https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104018
Bug ID: 104018
Summary: Comparison against 0 propagates into other statement
causing no-CSE from happening
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
int f(unsigned int a, unsigned int b) {
if (a > 0) {
return a == b;
} else {
return a == b;
}
}
int f2(unsigned int a, unsigned int b) {
if (a > 1) {
return a == b;
} else {
return a == b;
}
}
They should produce the same results but don't currently as in the first case
the >0 is turned into != 0 and then the 0 is propagated into the comparison and
then the comparison in the other BBSs are not able to be CSE'ed with the other
one.
