[Bug c/107176] New: Wrong code at -O0/-Os on x86_64-pc-linux-gnu

[shaohua.li at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107176

            Bug ID: 107176
           Summary: Wrong code at -O0/-Os on x86_64-pc-linux-gnu
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
  Target Milestone: ---

%gcc-tk -v
Using built-in specs.
COLLECT_GCC=gcc-tk
COLLECT_LTO_WRAPPER=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-b48d7ff3570fa0ebe7790275cf020d8885120338/libexec/gcc/x86_64-pc-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --disable-multilib --disable-bootstrap
--enable-languages=c,c++
--prefix=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-b48d7ff3570fa0ebe7790275cf020d8885120338
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20220928 (experimental) (GCC)
%
%gcc-tk -O0 a.c && ./a.out
1073741824
%
%gcc-tk -Os a.c && ./a.out 
0
%
%cat a.c
int a;
long b;
long c(unsigned d) { 
    return d; 
}
void e(d) { 
    a = d; 
}
int main() {
  b = 0;
  for (; b < 1; b = c(b - 90) + 90 + 1)
    ;
  e(b >> 2);
  printf("%d\n", a);
}
%

Compiler explorer: https://godbolt.org/z/zzMdosoKj