[LLVMbugs] [Bug 17459] New: wrong code at -O3 on x86_64-linux-gnu (affecting trunk and 3.3)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=17459

            Bug ID: 17459
           Summary: wrong code at -O3 on x86_64-linux-gnu (affecting 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. 

This is a regression from clang 3.2. 


$ clang-trunk -v
clang version 3.4 (trunk 191812)
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
1
$ clang-trunk -O3 small.c; a.out
3
$ clang-3.3 -O3 small.c; a.out
3
$ clang-3.2 -O3 small.c; a.out
1
$ 


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


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

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

int
main ()
{
  char i;
  int j;
  for (; g < 2; g++)
    {
      e = 1;
      for (e = 0; e < 2; e++)
        {
      int *k = &f;
      h = b == 0 ? g : 0;
      j = h ^ a ? h : h - a;
      i = j * g;
      *k = i;
      *d = 0;
        }
    }
  printf ("%d\n", f);
  return 0;
}

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