https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111456
Bug ID: 111456
Summary: [14 Regression] Dead Code Elimination Regression since
r14-3719-gb34f3736356
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/jqqP5baY8
Given the following code:
void foo(void);
static int i;
static int *j = &i;
static char l;
static void(a)(char) {}
static short(b)(short c, short d) { return c - d; }
static short(e)(short f, int g) {
return f < 0 || g < 0 || g >= 32 ? f : f >> g;
}
static short(h)(short f, int g) { return g >= 2 ?: f >> g; }
static char k(char m, short n) {
short o;
int *p = &i;
if (!(((m) >= 1) && ((m) <= 1))) {
__builtin_unreachable();
}
o = e(i, i);
if (h(1, o))
;
else {
m = 0;
for (; m >= -20; m = b(m, 9))
if (a(i), n) {
if (*p)
;
else
foo();
;
} else
return l;
}
return i;
}
int main() { k(0 <= 0 > *j, i); }
gcc-trunk -O2 does not eliminate the call to foo:
main:
movl i(%rip), %eax
testw %ax, %ax
js .L6
testl %eax, %eax
jne .L6
.L9:
xorl %eax, %eax
ret
.p2align 4,,10
.p2align 3
.L6:
movswl %ax, %edx
cmpw $1, %ax
jg .L9
testl %edx, %edx
je .L9
pushq %rbx
movl $3, %ebx
.L5:
cmpl $0, i(%rip)
je .L13
.L4:
subb $1, %bl
jne .L5
xorl %eax, %eax
popq %rbx
ret
.L13:
call foo
jmp .L4
gcc-13.2.0 -O2 eliminates the call to foo:
main:
xorl %eax, %eax
ret
Bisects to r14-3719-gb34f3736356
