[Bug tree-optimization/61045] New: Wrong constant folding

["ishiura-compiler at ml dot kwansei.ac.jp" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61045

            Bug ID: 61045
           Summary: Wrong constant folding
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ishiura-compiler at ml dot kwansei.ac.jp

GCC 4.4.7 - 4.10.0 for x86_64 miscompiles the following code.

   $ cat test.c

   int main (void)
   {
      long a = 0;
      long b = 0x7FFFFFFFFFFFFFFFL;
      int t = (a - 2) > (b - 1);
      if (t != 0) { __builtin_abort(); };
      return 0;
   }

   $ x86_64-unknown-linux-gnu-gcc-4.10.0 test.c -O2
   $ ./a.out 
   Aborted (core dumped)

   $ x86_64-unknown-linux-gnu-gcc-4.10.0 -v        
   Using built-in specs.
   COLLECT_GCC=x86_64-unknown-linux-gnu-gcc-4.10.0
  
COLLECT_LTO_WRAPPER=/usr/local/x86_64-tools/gcc-4.10.0/libexec/gcc/x86_64-unknown-linux-gnu/4.10.0/lto-wrapper
   Target: x86_64-unknown-linux-gnu
   Configured with: /home/hassy/gcc/configure
   --prefix=/usr/local/x86_64-tools/gcc-4.10.0/
   --with-gmp=/usr/local/gmp-5.1.1/ --with-mpfr=/usr/local/mpfr-3.1.2/
   --with-mpc=/usr/local/mpc-1.0.1/ --disable-multilib
   --disable-nls --enable-languages=c
   Thread model: posix
   gcc version 4.10.0 20140502 (experimental) (GCC)