https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110450
Bug ID: 110450
Summary: [14 Regression] Dead Code Elimination Regression at
-O2 since r14-261-g0ef3756adf0
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: theodort at inf dot ethz.ch
Target Milestone: ---
https://godbolt.org/z/KqcYxfevj
Given the following code:
void foo(void);
static int a = 1;
static int *b = &a, *c = &a;
static short d, e;
static char f = 11;
static char(g)(char h, int i) { return h << i; }
int main() {
if (f) *c = g(0 >= a, 3);
e = *c;
d = e % f;
if (d) {
__builtin_unreachable();
} else if (*b)
foo();
;
}
gcc-trunk -O2 does not eliminate the call to foo:
main:
movl a(%rip), %eax
xorl %edx, %edx
testl %eax, %eax
setle %dl
leal 0(,%rdx,8), %edx
movl %edx, a(%rip)
jle .L8
xorl %eax, %eax
ret
.L8:
pushq %rax
call foo
xorl %eax, %eax
popq %rdx
ret
gcc-13.1.0 -O2 eliminates the call to foo:
main:
movl a(%rip), %edx
xorl %eax, %eax
testl %edx, %edx
setle %al
leal 0(,%rax,8), %eax
movl %eax, a(%rip)
xorl %eax, %eax
ret
Bisects to r14-261-g0ef3756adf0
