Comment 2 for bug 836401

Also occurs when building LLVM trunk. See:
 http://builds.linaro.org/toolchain/llvm-3.0~svn138625/logs/armv7l-natty-cbuild172-ursa1-cortexa9r1/llvm-build.txt

/scratch/cbuild/slave/slaves/ursa1/llvm-3.0~svn138625/llvm/llvm-3.0~/tools/clang/unittests/AST/APValueTest.cpp: In member function 'virtual void {anonymous}::APValue_Diagnostics_Test::TestBody()':
/scratch/cbuild/slave/slaves/ursa1/llvm-3.0~svn138625/llvm/llvm-3.0~/tools/clang/unittests/AST/APValueTest.cpp:77:1: error: insn does not satisfy its constraints:
(insn 1267 1266 1269 72 (set (subreg:SI (reg:DI 1327) 0)
        (ior:SI (ashift:SI (reg:SI 1330)
                (const_int -16 [0xfffffffffffffff0]))
            (subreg:SI (reg:DI 1327) 0))) /scratch/cbuild/slave/slaves/ursa1/llvm-3.0~svn138625/llvm/llvm-3.0~/include/llvm/ADT/APInt.h:140 257 {*arith_shiftsi}
     (nil))
/scratch/cbuild/slave/slaves/ursa1/llvm-3.0~svn138625/llvm/llvm-3.0~/tools/clang/unittests/AST/APValueTest.cpp:77:1: internal compiler error: in extract_constrain_insn_cached, at recog.c:2028