https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110173
Bug ID: 110173
Summary: [14 Regression] Missed Dead Code Elimination when
using __builtin_unreachable since r14-569-g21e2ef2dc25
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/ssja5dKdY
void foo(void);
static int e, f, n, *g, **h = &g;
static short m;
void __assert_fail() __attribute__((__noreturn__));
static short(a)(short b) { return b; }
static short(c)(short d) {
if (!(((d) >= 1) && ((d) <= 1))) {
__builtin_unreachable();
}
return 0;
}
static int *j();
static void k(int *l, char) {
*l = 0;
if (g == &e || g == 0 || g == &f);
else {
foo();
__assert_fail();
}
c(f < 5);
}
static void i() { *h = j(); }
static int *j(unsigned o) {
char p;
if (g == &f || g == 0);
else
__assert_fail();
p = m > (a(1) && o);
k(&n, p);
if (g == 0);
else
__assert_fail();
return 0;
}
int main() { i(); }
gcc-trunk -Os -S:
main:
movq g(%rip), %rax
testq %rax, %rax
je .L2
cmpq $f, %rax
je .L2
.L3:
pushq %rsi
xorl %eax, %eax
call __assert_fail
.L2:
xorl %ecx, %ecx
movl %ecx, n(%rip)
testq %rax, %rax
jne .L3
xorl %edx, %edx
movq %rdx, g(%rip)
ret
main:
pushq %rsi
movq g(%rip), %rax
cmpq $f, %rax
je .L2
testq %rax, %rax
jne .L13
.L2:
xorl %ecx, %ecx
movl %ecx, n(%rip)
cmpq $f, %rax
je .L3
testq %rax, %rax
je .L11
call foo
.L13:
xorl %eax, %eax
call __assert_fail
.L3:
testq %rax, %rax
jne .L13
.L11:
xorl %eax, %eax
movq %rax, g(%rip)
xorl %eax, %eax
popq %rdx
ret
Bisects to r14-569-g21e2ef2dc25
