[LLVMbugs] [Bug 17338] New: wrong code at -O0 in 32-bit mode (affecting all clang versions on x86_64-linux-gnu and MacOS X)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=17338

            Bug ID: 17338
           Summary: wrong code at -O0 in 32-bit mode (affecting all clang
                    versions on x86_64-linux-gnu and MacOS X)
           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 older
versions) on x86_64-linux-gnu at -O0 in 32-bit mode.  

It also affects MacOS X. 

The issue seems to be how the long long literal 0xFFFFFFFFLL is handled. 


$ clang-trunk -v
clang version 3.4 (trunk 191183)
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 -m32 -O0 small.c; a.out
0
$ clang-trunk -m32 -O1 small.c; a.out
1
$ clang-3.3 -m32 -O0 small.c; a.out
0
$ clang-3.2 -m32 -O0 small.c; a.out
0
$ gcc-trunk -m32 -O0 small.c; a.out
1
$ icc -m32 -O0 small.c; a.out
1
$


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


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

int main ()
{
  long long t = -1; 
  int a = (0xFFFFFFFFLL & t) > 0;

  printf ("%d\n", a);

  return 0;
}

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