https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90074
Bug ID: 90074
Summary: wrong debug info 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's a latent issue which affects 4.8-6, and 8-trunk. Gcc-7 works fine.
It happens at -O3 only. Bisect between gcc-7 and gcc-8 points to r255267.
$ gcc-trunk -v
gcc version 9.0.1 20190412 (experimental) [trunk revision 270309] (GCC)
$ gdb -v
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
## wrong result ##
$ gcc-trunk abc.c outer.c -g -O3
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x400394: file abc.c, line 12.
Breakpoint 1, main () at abc.c:12
12 optimize_me_not();
$1 = 0
## correct result ##
$ gcc-trunk abc.c outer.c -g
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x40049f: file abc.c, line 12.
Breakpoint 1, main () at abc.c:12
12 optimize_me_not();
$1 = 7
$ cat abc.c
char a;
short b[7][1];
int main() {
int i, c;
a = 0;
i = 0;
for (; i < 7; i++) {
c = 0;
for (; c < 1; c++)
b[i][c] = 0;
}
optimize_me_not();
}
$ cat outer.c
void optimize_me_not() {}
$ cat cmds
b 12
r
p i
kill
q
