Extended Description

This is the reduction from libmng & Qt.

Everythign was ok some weeks ago. I've tried to rebuild Qt after SETCC-removal
patch landed.

Steps to reproduce:

~/proj/llvm/build/Release/bin $ ./opt bugpoint-reduced-simplified.bc -instcombine -f
opt: /home/asl/proj/llvm/src/include/llvm/Support/Casting.h:199: typename
llvm::cast_retty<To, From>::ret_type llvm::cast(const Y&) [with X =
llvm::ShiftInst, Y = llvm::Instruction*]: Assertion `isa(Val) && "cast()
argument of incompatible type!"' failed.
./opt((anonymous namespace)::PrintStackTrace()+0x1f)[0x836a96f]
/lib/libc.so.6(abort+0xeb)[0xb7d96133]
/lib/libc.so.6(__assert_fail+0xeb)[0xb7d8e4f3]
./opt((anonymous namespace)::InstCombiner::FoldSelectOpOp(llvm::SelectInst&,
llvm::Instruction*, llvm::Instruction*)+0x963)[0x81843a3]

Bytecode attached.