https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89792
Bug ID: 89792
Summary: gcc generates wrong debug information at -O3
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-8 and gcc-trunk. gcc-7 works fine.
The testcase looks similar to Bug 89463. But they affect different gcc versions
and bisect points to different revisions. It would be helpful to have them
fixed.
For this bug, bisect points to r255569.
$ cat abc.c
volatile int a, b;
static int c;
int main() {
int i;
b = 0;
i = 0;
for (; i < 3; i++)
a = c;
i = 0;
for (; i < 5; i++)
;
optimize_me_not();
}
$ cat outer.c
void optimize_me_not() {}
$ cat cmds
b 12
r
p i
kill
q
#Correct output#
$ gcc-trunk -g abc.c outer.c
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x400496: file abc.c, line 12.
Breakpoint 1, main () at abc.c:12
12 optimize_me_not();
$1 = 5
#Wrong output#
$ gcc-trunk -g -O3 abc.c outer.c
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x4003ae: file abc.c, line 12.
Breakpoint 1, main () at abc.c:12
12 optimize_me_not();
$1 = 0
