[Bug tree-optimization/60930] 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=60930

            Bug ID: 60930
           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 4.7 - 4.10 for i686 and x86_64 miscompiles the following code.

    $ cat error.c

    #include <stdio.h>
    int x = 1;
    main ()
    {
        unsigned long long t = 0xffffffffffffffffLLU * (0xffffffffLU * x);
        if (t != 0xffffffff00000001LLU) {
            printf ("Error (t == %llu)\n", t);
        }
        return 0;
    }

    $ x86_64-unknown-linux-gnu-gcc-4.10.0 error.c -O1
    $ ./a.out
    Error 1

    $ 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-master/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-1.0.2/ --disable-multilib
    --disable-nls --enable-languages=c
    Thread model: posix
    gcc version 4.10.0 20140422 (experimental) (GCC)

The status of the other versions are as follows:

    (x86_64)
    GCC-4.7.3 OK
    GCC-4.8.3 (prerelease) Error
    GCC-4.9.1 (prerelease) Error
    GCC-4.10.0 (experimental) Error

    (i686)
    GCC-4.7.3 Error
    GCC-4.8.3 (prerelease) Error
    GCC-4.9.1 (prerelease) Error
    GCC-4.10.0 (experimental) Error