https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106244
Bug ID: 106244
Summary: Failure to optimize (1 << x) & 1 to `x == 0` if
separated into multiple statements
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
#include <stdint.h>
int8_t f(int8_t x)
{
int8_t sh = 1 << x;
return sh & 1;
}
This can be optimized to `return x == 0;`. This transformation is done by LLVM,
but not by GCC.
PS: For some reason GCC manages to do this optimization if I replace `f` with
`return (1 << x) & 1;` instead of having it spelled out in 2 statements.
