Fix PR10475

- ISD::SHL/SRL/SRA must have either both scalar or both vector operands
  but TLI.getShiftAmountTy() so far only return scalar type. As a
  result, backend logic assuming that breaks.
- Rename the original TLI.getShiftAmountTy() to
  TLI.getScalarShiftAmountTy() and re-define TLI.getShiftAmountTy() to
  return target-specificed scalar type or the same vector type as the
  1st operand.
- Fix most TICG logic assuming TLI.getShiftAmountTy() a simple scalar
  type.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176364 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/ISDOpcodes.h

@@ -311,8 +311,10 @@ namespace ISD {
     /// the shift amount can be any type, but care must be taken to ensure it is
     /// large enough.  TLI.getShiftAmountTy() is i8 on some targets, but before
     /// legalization, types like i1024 can occur and i8 doesn't have enough bits
-    /// to represent the shift amount.  By convention, DAGCombine and
-    /// SelectionDAGBuilder forces these shift amounts to i32 for simplicity.
+    /// to represent the shift amount.
+    /// When the 1st operand is a vector, the shift amount must be in the same
+    /// type. (TLI.getShiftAmountTy() will return the same type when the input
+    /// type is a vector.)
     SHL, SRA, SRL, ROTL, ROTR,
 
     /// Byte Swap and Counting operators.