https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98304
Bug ID: 98304
Summary: Failure to optimize bitwise arithmetic pattern
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
int f1(int n)
{
return n - (((n > 63) ? n : 63) & -64);
}
This can be optimized to `return (n <= 63) ? n : (n & 63);` (and presumably the
same optimization should be doable with other powers of 2).
PS: I found this optimization while looking at how this :
int f1(int n)
{
while (n >= 64)
n -= 64;
return n;
}
is optimized. LLVM outputs the first example I gave here, while GCC outputs the
optimization I gave here.
