CostModel: Add parameter to instruction cost to further classify operand values

On certain architectures we can support efficient vectorized version of
instructions if the operand value is uniform (splat) or a constant scalar.
An example of this is a vector shift on x86.

We can efficiently support

for (i = 0 ; i < ; i += 4)
  w[0:3] = v[0:3] << <2, 2, 2, 2>

but not

for (i = 0; i < ; i += 4)
  w[0:3] = v[0:3] << x[0:3]

This patch adds a parameter to getArithmeticInstrCost to further qualify operand
values as uniform or uniform constant.

Targets can then choose to return a different cost for instructions with such
operand values.

A follow-up commit will test this feature on x86.

radar://13576547

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178807 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCTargetTransformInfo.cpp

@@ -86,7 +86,9 @@ public:
   virtual unsigned getNumberOfRegisters(bool Vector) const;
   virtual unsigned getRegisterBitWidth(bool Vector) const;
   virtual unsigned getMaximumUnrollFactor() const;
-  virtual unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty) const;
+  virtual unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty,
+                                          OperandValueKind,
+                                          OperandValueKind) const;
   virtual unsigned getShuffleCost(ShuffleKind Kind, Type *Tp,
                                   int Index, Type *SubTp) const;
   virtual unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
@@ -166,11 +168,14 @@ unsigned PPCTTI::getMaximumUnrollFactor() const {
   return 2;
 }
 
-unsigned PPCTTI::getArithmeticInstrCost(unsigned Opcode, Type *Ty) const {
+unsigned PPCTTI::getArithmeticInstrCost(unsigned Opcode, Type *Ty,
+                                        OperandValueKind Op1Info,
+                                        OperandValueKind Op2Info) const {
   assert(TLI->InstructionOpcodeToISD(Opcode) && "Invalid opcode");
 
   // Fallback to the default implementation.
-  return TargetTransformInfo::getArithmeticInstrCost(Opcode, Ty);
+  return TargetTransformInfo::getArithmeticInstrCost(Opcode, Ty, Op1Info,
+                                                     Op2Info);
 }
 
 unsigned PPCTTI::getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,