[llvm-bugs] [Bug 39620] New: wrong code at -Os and above on x86_64-linux-gnu

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39620

            Bug ID: 39620
           Summary: wrong code at -Os and above on x86_64-linux-gnu
           Product: clang
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: su at cs.ucdavis.edu
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org,
                    richard-llvm at metafoo.co.uk

Tested with trunk revision 346531. 

$ clangpolly -v
clang version 8.0.0 (http://llvm.org/git/clang.git
7e12b9765a105da269d3e41f2edc62ccdf7a4c35) (http://llvm.org/git/llvm.git
6517c35cb714c419a87b1bbe8929191b02e2915a)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/su/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.4.0
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/6.0.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.0.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$
$ clangpolly -O1 small.c; ./a.out
0
$
$ clangpolly -Os small.c
$ ./a.out
$


---------------------------------------------


int printf (const char *, ...);

int a, b, *c = &a, *d;
short e, f;

short g (unsigned short h, unsigned short i)
{ 
  return h % i;
}

void j (char h)
{ 
  for (; h < 1; h++)
    printf ("%d\n", e);
}

unsigned char k (int *h)
{ 
  int **l = &d;
  *c = 45890;
  d = h;
  f = (**l & ((55 | 7009) - 6)) - **l;
  *h = g (**l, f) & 48314;
  return **l;
}

int main ()
{ 
  j (k(&a) > 0);
  return 0;
}

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