https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111801
Bug ID: 111801
Summary: [14 Regression] Missed Dead Code Elimination since
r14-4141-gbf6b107e2a3
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/47fbssWd3
Given the following code:
void foo(void);
static struct {
signed a;
} b, c, *e = &b;
static struct {
unsigned d;
} g = {109};
static int f;
static int *h;
static int **i = &h;
int main() {
f = 1;
if (b.a) f = 8;
int *j = *i;
if (j == &g == 0)
if (!(((g.d) >= 109) && ((g.d) <= 109))) {
__builtin_unreachable();
}
if (f)
;
else {
c = *e;
foo();
}
}
gcc-trunk -O2 does not eliminate the call to foo:
main:
movl $1, f(%rip)
movl b(%rip), %esi
testl %esi, %esi
je .L10
movl $8, f(%rip)
.L10:
cmpq $g, h(%rip)
je .L7
movl f(%rip), %ecx
testl %ecx, %ecx
je .L12
.L7:
xorl %eax, %eax
ret
.L12:
pushq %rax
call foo
xorl %eax, %eax
popq %rdx
ret
gcc-13.2.0 -O2 eliminates the call to foo:
main:
movl $1, f(%rip)
movl b(%rip), %eax
testl %eax, %eax
je .L2
movl $8, f(%rip)
.L2:
xorl %eax, %eax
ret
Bisects to r14-4141-gbf6b107e2a3
