[LLVMbugs] [Bug 18165] New: wrong code at -Os and above

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=18165

            Bug ID: 18165
           Summary: wrong code at -Os and above
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          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
3.3 and 3.2) on x86_64-linux-gnu at -Os and above in both 32-bit and 64-bit
modes. 

It is also miscompiled by clang 3.0 and 3.1 at -O3, making it a regression from
2.9.

It also seems to affect MacOS X. 

$ clang-trunk -v
clang version 3.5 (trunk 196634)
Target: x86_64-unknown-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 -O1 small.c; a.out
0
$ clang-trunk -Os small.c; a.out
-1
$ clang-3.3 -Os small.c; a.out
-1
$ clang-3.2 -Os small.c; a.out
-1
$ clang-3.1 -Os small.c; a.out
0
$ clang-3.1 -O3 small.c; a.out
-1
$ clang-3.0 -O3 small.c; a.out
-1
$ clang-2.9 -O3 small.c; a.out
0
$ 
$ gcc-trunk -Os small.c; a.out
0
$ icc -Os small.c; a.out
0
$ 


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


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

struct
{
  int f0;
  int f1;
  int f2;
} a, e;

int b, c = 1, d, f, g, h;

static int
fn1 (unsigned char p)
{
 lbl:
  for (g = 0; g; g++)
    {
      if (c)
    break;
      p && (d |= 1);
    }
  for (e.f1 = 0; e.f1 < 21; e.f1 += 2)
    {
      h = 0;
      if (a.f0)
    goto lbl;
      f |= a.f2 |= p++ || b--;
    }
  return 0;
}

int
main ()
{
  fn1 (128);
  printf ("%d\n", b);
  return 0;
}

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20131207/f7c2a0e6/attachment.html>