[DAG][X86] Add isNegatibleForFree/GetNegatedExpression override placeholders. NFCI.

Continuing to undo the rL372756 reversion.

Differential Revision: https://reviews.llvm.org/D67557

llvm-svn: 374345

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -41380,6 +41380,22 @@ static SDValue combineFneg(SDNode *N, SelectionDAG &DAG,
   return SDValue();
 }
 
+char X86TargetLowering::isNegatibleForFree(SDValue Op, SelectionDAG &DAG,
+                                           bool LegalOperations,
+                                           bool ForCodeSize,
+                                           unsigned Depth) const {
+  return TargetLowering::isNegatibleForFree(Op, DAG, LegalOperations,
+                                            ForCodeSize, Depth);
+}
+
+SDValue X86TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG,
+                                                bool LegalOperations,
+                                                bool ForCodeSize,
+                                                unsigned Depth) const {
+  return TargetLowering::getNegatedExpression(Op, DAG, LegalOperations,
+                                              ForCodeSize, Depth);
+}
+
 static SDValue lowerX86FPLogicOp(SDNode *N, SelectionDAG &DAG,
                                  const X86Subtarget &Subtarget) {
   MVT VT = N->getSimpleValueType(0);

llvm/lib/Target/X86/X86ISelLowering.h

@@ -802,6 +802,17 @@ namespace llvm {
     /// and some i16 instructions are slow.
     bool IsDesirableToPromoteOp(SDValue Op, EVT &PVT) const override;
 
+    /// Return 1 if we can compute the negated form of the specified expression
+    /// for the same cost as the expression itself, or 2 if we can compute the
+    /// negated form more cheaply than the expression itself. Else return 0.
+    char isNegatibleForFree(SDValue Op, SelectionDAG &DAG, bool LegalOperations,
+                            bool ForCodeSize, unsigned Depth) const override;
+
+    /// If isNegatibleForFree returns true, return the newly negated expression.
+    SDValue getNegatedExpression(SDValue Op, SelectionDAG &DAG,
+                                 bool LegalOperations, bool ForCodeSize,
+                                 unsigned Depth) const override;
+
     MachineBasicBlock *
     EmitInstrWithCustomInserter(MachineInstr &MI,
                                 MachineBasicBlock *MBB) const override;