https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111294
Bug ID: 111294
Summary: [14 Regression] Missed Dead Code Elimination since
r14-573-g69f1a8af45d
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/7GTzj8Ea1
Given the following code:
void foo(void);
static short a;
static int b, c, d;
static int *e, *f = &d;
static int **g = &e;
static unsigned char h;
static short(i)(short j, int k) { return j > k ?: j; }
static char l() {
if (a) return b;
return c;
}
int main() {
b = 0;
for (; b < 5; ++b)
;
h = l();
if (a ^ 3 >= i(h, 11))
a = 0;
else {
*g = f;
if (e == &d & b) {
__builtin_unreachable();
} else
foo();
;
}
}
gcc-trunk -Os does not eliminate the call to foo:
main:
movswl a(%rip), %eax
xorl %edx, %edx
movl $5, b(%rip)
testw %ax, %ax
je .L2
movl $5, %edx
.L2:
cmpl $3, %edx
setle %dl
movzbl %dl, %edx
cmpl %edx, %eax
je .L3
movw $0, a(%rip)
xorl %eax, %eax
ret
.L3:
pushq %rax
movq $d, e(%rip)
call foo
xorl %eax, %eax
popq %rdx
ret
gcc-13.2.0 -Os eliminates the call to foo:
main:
movl $5, b(%rip)
xorl %eax, %eax
movw $0, a(%rip)
ret
Bisects to r14-573-g69f1a8af45d
