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

llvm-svn: 178807

1 files changed, 6 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp b/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
index 4cd1b80dc0b..012ff8ad833 100644
--- a/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
+++ b/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
@@ -85,7 +85,9 @@ public:
   virtual unsigned getNumberOfRegisters(bool Vector) const;
   virtual unsigned getMaximumUnrollFactor() const;
   virtual unsigned getRegisterBitWidth(bool Vector) 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,
@@ -193,7 +195,9 @@ unsigned BasicTTI::getMaximumUnrollFactor() const {
   return 1;
 }
 
-unsigned BasicTTI::getArithmeticInstrCost(unsigned Opcode, Type *Ty) const {
+unsigned BasicTTI::getArithmeticInstrCost(unsigned Opcode, Type *Ty,
+                                          OperandValueKind,
+                                          OperandValueKind) const {
   // Check if any of the operands are vector operands.
   int ISD = TLI->InstructionOpcodeToISD(Opcode);
   assert(ISD && "Invalid opcode");