https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112344
Bug ID: 112344
Summary: [14 Regression] Wrong code at -O2 on
x86_64-pc-linux-gnu
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: jwzeng at nuaa dot edu.cn
Target Milestone: ---
I compiled the following code with gcc at -O2, and it produces the wrong code.
The correct output result should be 13, but 73 was output under -O2.
This bug seems to only exist on gcc-trunk. The gcc-tk used below is the
earliest version I can use that triggers this bug.
Compiler explorer: https://godbolt.org/z/8hq64asT5
```c
$ cat test.c
int printf(const char *, ...);
int a;
void b() {
long c = 3;
unsigned int d = 50253292;
int e = 2147483648;
for (; a < 5; a++)
do {
e += 4;
d -= c;
} while (e < 20);
printf("%d\n", d);
}
int main() { b(); }
$
$ gcc-tk test.c -O2; ./test.c
73
$
$ gcc-tk test.c -O0; ./test.c
13
$ gcc-tk test.c -O1; ./test.c
13
$ gcc-tk test.c -O3; ./test.c
13
$ gcc-tk test.c -Os; ./test.c
13
$ ccomp test.c -O1; ./a.out
13
$
$ gcc-tk --version
gcc (GCC) 14.0.0 20230922 (experimental) [master r14-4213-gd35e12e1c0]
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$
$ ccomp --version
The CompCert C verified compiler, version 3.12
```
