[LLVMbugs] [Bug 16463] New: wrong code at -O3 on x86_64-linux-gnu (in both 32-bit and 64-bit modes)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=16463

            Bug ID: 16463
           Summary: wrong code at -O3 on x86_64-linux-gnu (in both 32-bit
                    and 64-bit modes)
           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 current clang trunk (as well as clang 3.2
and 3.3) on x86_64-linux-gnu at -O3 in both 32-bit and 64-bit modes, resulting
in a SIGFPE. 

$ clang-trunk -v
clang version 3.4 (trunk 184829)
Target: x86_64-pc-linux-gnu
Thread model: posix
$ clang-trunk -O2 reduced.c
$ a.out
$ clang-trunk -O3 reduced.c
$ a.out
Floating point exception (core dumped)
$ clang-3.3 -O3 reduced.c
$ a.out
Floating point exception (core dumped)
$ clang-3.2 -O3 reduced.c
$ a.out
Floating point exception (core dumped)
$ 


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

int a, b, d, e, f, g;

int * foo (int p)
{
  b = -2;
  for (; b; ++b)
    for (; d; ++d) {
      g = p == 0 ? 0 : 1 / p;
      e = 0;
      for (; e < 38; e++) {
    g--;
    if (a)
      return 0;
      }
    }
  return 0;
}

int main ()
{
  foo (1 & f);
  return 0;
}

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