[LLVMbugs] [Bug 17524] New: wrong code (SIGFPE) at -O3 (affecting both clang trunk and 3.3)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=17524

            Bug ID: 17524
           Summary: wrong code (SIGFPE) at -O3 (affecting both clang trunk
                    and 3.3)
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: LLVM Codegen
          Assignee: unassignedclangbugs at nondot.org
          Reporter: su at cs.ucdavis.edu
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

The following code is miscompiled by the current clang trunk and clang 3.3 on
x86_64-linux-gnu at -O3 in both 32-bit and 64-bit modes.  

It also affects MacOS X. 


$ clang-trunk -v
clang version 3.4 (trunk 192279)
Target: x86_64-pc-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
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/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
$ 
$ clang-trunk -O2 small.c; a.out
$ clang-3.2 -O3 small.c; a.out
$ gcc-trunk -O3 small.c; a.out
$ 
$ clang-trunk -O3 small.c; a.out
Floating point exception (core dumped)
$ clang-3.3 -O3 small.c; a.out
Floating point exception (core dumped)
$ 


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


int a, b, c, d, f, g, h, i;
unsigned int e;

int
fn1 ()
{
  short j = 0;
  for (; j != 8; ++j)
    {
      if (b)
    return 0;
      g = 0;
      short k = b;
      f = k == 0 ? 0 : e / k;
      h = f + j < 0 ? 0 : 1;
      c = 0;
      if (1 != b)
    return 0;
      if (j)
    i = a ? 0 : 1 % a;
    }
  return 1;
}

int
main ()
{
  for (; d != -6; d--)
    fn1 ();
  return 0;
}

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