https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100969
Bug ID: 100969
Summary: Incorrect debug info for struct under O1 optimization
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: liyd2021 at gmail dot com
Target Milestone: ---
Reproduced on: gcc 11.1.0, 9.3.0, 8.4.0 with gdb or lldb (Ubuntu 20.04.2)
$ cat test.c
struct foo { int a, b, c; };
void not_opt(struct foo x) __attribute__((noipa));
void not_opt(struct foo x) {}
int main ()
{
struct foo f = { 7, 8, 9 };
not_opt(f);
return 0;
}
Compile command:
$ gcc -g -O1 test.c -o test
$ gcc --verbose
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/vm/opt/gcc-11.1.0/libexec/gcc/x86_64-unknown-linux-gnu/11.1.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /home/vm/var/tmp/vm/gcc-11.1.0_source/gcc-11.1.0/configure
--prefix=/home/vm/opt/gcc-11.1.0 --enable-bootstrap --enable-shared
--enable-threads=posix --enable-checking=release --with-system-zlib
--enable-__cxa_atexit --disable-libunwind-exceptions --enable-linker-build-id
--enable-languages=c,c++,lto --disable-vtable-verify
--with-default-libstdcxx-abi=new --enable-libstdcxx-debug
--without-included-gettext --enable-plugin --disable-initfini-array
--disable-libgcj --enable-plugin --disable-multilib --with-tune=generic
--build=x86_64-unknown-linux-gnu --target=x86_64-unknown-linux-gnu
--host=x86_64-unknown-linux-gnu --with-pkgversion=vm
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 11.1.0
Debugging with gdb:
(gdb) l
1 struct foo { int a, b, c; };
2
3 void not_opt(struct foo x) __attribute__((noipa));
4 void not_opt(struct foo x) {}
5
6 int main ()
7 {
8 struct foo f = { 7, 8, 9 };
9 not_opt(f);
10 return 0;
(gdb) b 9
(gdb) r
(gdb) print f
$1 = {a = 7, b = 8, c = 0} <-- **BUG**: c should be 9
LLDB also reports c = 0. Should be a debug-info bug.
