[LLVMbugs] [Bug 18447] New: wrong code at -Os (affecting all clang versions after 3.0 on x86_64-linux-gnu and MacOS X)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=18447

            Bug ID: 18447
           Summary: wrong code at -Os (affecting all clang versions after
                    3.0 on x86_64-linux-gnu and MacOS X)
           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 (and older
versions from clang 3.0) on x86_64-linux-gnu and MacOS X at -Os in both 32-bit
and 64-bit modes.  

This is a regression from 2.9. 

$ clang-trunk -v
clang version 3.5 (trunk 199011)
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
29052
$ clang-2.9 -Os small.c; a.out
29052
$
$ clang-trunk -Os small.c; a.out
-36484
$ 


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


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

short a, c; 
int b, d, r; 

static unsigned int
foo () 
{
  int e; 
  b = 0;
  for (a = 0; a < 2; a++)
    {
      if (b != 1)
    {
      e = a - 7; 
      c = e * 60694;
      r = c;
    }
      for (; d; d++)
    ;
    }
  return 0;
}

int
main ()
{
  foo ();
  printf ("%d\n", r);
  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/20140111/98467ae5/attachment.html>