Implement a pretty general logical shift propagation

framework, which is good at ripping through bitfield
operations.  This generalize a bunch of the existing
xforms that instcombine does, such as 
  (x << c) >> c -> and
to handle intermediate logical nodes.  This is useful for
ripping up the "promote to large integer" code produced by
SRoA.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112304 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/InstCombine/InstCombineCasts.cpp

@@ -566,8 +566,7 @@ Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
           
         if (CI.getType() == In->getType())
           return ReplaceInstUsesWith(CI, In);
-        else
-          return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
+        return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
       }
     }
   }