[LLVMbugs] [Bug 19636] New: Wrong constant folding

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=19636

            Bug ID: 19636
           Summary: Wrong constant folding
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: ishiura-compiler at ml.kwansei.ac.jp
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

LLVM + clang 3.5 for i386 and x86_64 miscompiles the following code.

  $ cat test.c

    int main (void)
    {
      int a = 0;
      unsigned long c = ((1LU & (1 | (0 < a))) % 1 + 0xffffffffffffffffLU);
      double t = c % 2;
      if (t != 1.0) __builtin_abort();
      return 0;
    }

  $ clang test.c -O0
  $ ./a.out
    Aborted (core dumped)

  $ clang -v
    clang version 3.5.0
    Target: x86_64-unknown-linux-gnu
    Thread model: posix
    Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
    Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
    Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
    Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
    Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
    Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.2
    Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
    Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.0
    Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
    Candidate multilib: .;@m64
    Candidate multilib: 32;@m32
    Selected multilib: .;@m64

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