Rectify r213231. Use proper version of 'ComputeNumSignBits'.

Earlier when the code was in InstCombine, we were calling the version of ComputeNumSignBits in InstCombine.h
that automatically added the DataLayout* before calling into ValueTracking.
When the code moved to InstSimplify, we are calling into ValueTracking directly without passing in the DataLayout*.
This patch rectifies the same by passing DataLayout in ComputeNumSignBits.

llvm-svn: 213295

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -1347,7 +1347,7 @@ static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
     return X;
 
   // Arithmetic shifting an all-sign-bit value is a no-op.
-  unsigned NumSignBits = ComputeNumSignBits(Op0);
+  unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL);
   if (NumSignBits == Op0->getType()->getScalarSizeInBits())
     return Op0;