https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89791
Bug ID: 89791
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-4.6 to gcc-trunk. The expected output is "i=7" or <optimized
out>. With "-O3", it outputs "i=0".
I am using two files since "noipa" attribute directive is not supported in
early gcc versions.
Bisect points to r154402.
commit 43e54ec3e93dd2ef495375ead1f1eac467a727d1
Author: aoliva <aoliva@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Sat Nov 21 05:06:24 2009 +0000
* tree-ssa.c (find_released_ssa_name): Handle NULL wi.
(insert_debug_temp_for_var_def): Handle degenerate PHI nodes.
(insert_debug_temps_for_defs): Handle PHI nodes.
* tree-ssa-dom.c (degenerate_phi_result): Don't crash on released
SSA names.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@154402
138bc75d-0d04-0410-961f-82ee72b054a4
$ gcc-trunk -v
gcc version 9.0.1 20190321 (experimental) [trunk revision 269832] (GCC)
$ cat abc.c
int main() {
int i = 0;
for (; i < 7; i++)
;
optimize_me_not();
}
$ cat outer.c
void optimize_me_not() {}
# correct output #
$ gcc-trunk -g abc.c outer.c
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x40046d: file abc.c, line 5.
Breakpoint 1, main () at abc.c:5
5 optimize_me_not();
$1 = 7
# Wrong output #
$ gcc-trunk -g abc.c outer.c
$ gdb -x cmds -batch a.out
Breakpoint 1 at 0x400380: file abc.c, line 5.
Breakpoint 1, main () at abc.c:5
5 optimize_me_not();
$1 = 0
