https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93954
Bug ID: 93954
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 appears to be a regression in gcc-8. The code is pretty self-explanatory.
Bisection points to g:bd2b9f1e2d67ec8e88c977154ecfee
$ gcc-trunk -v
gcc version 10.0.1 20200226 (experimental) [master revision
4d213bf6011:5d3c19b2ec6:ce25177f505ea75b3c0833c3f3f0072b97ee1b44] (GCC)
#It incorrectly prints i = 2580636200
$ gcc-trunk -g-O3 abc.c
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x4003a0: file abc.c, line 4.
Breakpoint 1, main () at abc.c:4
4 ;// b here
$1 = 2580636200
Kill the program being debugged? (y or n) [answered Y; input not from terminal]
[Inferior 1 (process 17508) killed]
$ cat abc.c
int main() {
unsigned i = 2580636200;
i--;
;// b here
}
$ cat cmds
b abc.c:4
r
p i
kill
q
