[LLVMbugs] [Bug 16523] New: wrong code (SIGFPE) at -O3 on x86_64-linux-gnu (both 32-bit and 64-bit modes)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=16523

            Bug ID: 16523
           Summary: wrong code (SIGFPE) at -O3 on x86_64-linux-gnu (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 the 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 185306)
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)
$ 


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

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

struct
{
  char x; 
  int y;
} **c, d; 

int main ()
{
  d.x = 1; 
  for (; e <= 0; e++)
    if (!d.x) {
      *c = 0;
      g = b ? 0 : a / b;
      f = g * e;
    }

  return 0;
}

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