https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89801
Bug ID: 89801
Summary: gcc generates wrong debug information at -O2
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: qrzhang at gatech dot edu
Target Milestone: ---
It affects gcc-6 to gcc-trunk. gcc-5 works fine.
Bisect points to r222305.
$ gcc-trunk -v
gcc version 9.0.1 20190322 (experimental) [trunk revision 269869] (GCC)
$ gdb -v
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
# Correct ouutput #
$ gcc-trunk -g abc.c outer.c
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x400486: file abc.c, line 9.
Breakpoint 1, d () at abc.c:9
9 c = 3;
$1 = 1
# Incorrect output at O2 #
$ gcc-trunk -g abc.c outer.c -O2
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x400380: file abc.c, line 9.
Breakpoint 1, main () at abc.c:18
18 for (; i < 5; i++)
$1 = 0
$ cat abc.c
long a, b;
static int c, f;
static long d() {
int *e = &c;
int i = 0;
for (; i < 1; i++)
;
*e ^= b;
c = 3;
for (; 0;)
optimize_me_not();
;
}
int main() {
int i;
d();
i = 0;
for (; i < 5; i++)
for (; f; f++)
;
a = c;
}
$ cat outer.c
void optimize_me_not() {}
$ cat cmds
b 9
r
p i
kill
q
