https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117368
Bug ID: 117368
Summary: Miscompile with different optimization flags
Product: gcc
Version: 14.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: yunboni at smail dot nju.edu.cn
Target Milestone: ---
Created attachment 59500
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=59500&action=edit
The preprocessed file
When I compiled this code with O2 and O3 flags, its outputs were different:
#define a() 0
#include <stdint.h>
#include <stdio.h>
char c[];
char *d;
int32_t e;
uint32_t f[];
const int32_t *i;
int b() {}
int v(int n, char *o) {
char *g = o;
d = c;
while (n) {
d++;
n /= 10;
}
while (d != c)
*g++ = *--d;
*g++ = '\0';
return g - o - 1;
}
int h(int n, char) {
char p[3];
int l = v(n, p);
return l;
}
void m() {}
const int32_t *q();
uint16_t r() {
int16_t s[1][3][2];
int32_t *t = &e, j, k;
for (; j < 3; j++)
for (k = 0; k < 2; k++)
s[h(53, 0) - 2][j][k] = 1;
if ((*t = b() - 1 + s[0][0][1]) != m)
;
else
for (;;)
if (*i)
if (f[a()]) {
const int32_t **u = &i;
*u = q();
}
}
const int32_t *q() {}
int main() {
r();
printf("%d\n", e);
}
For O2, its output is: 0
For O3, its output is: -1
The details can be found here: https://godbolt.org/z/334KGnj77
