AMDGPU: Factor out fneg fold predicate function

llvm · Feb 3, 2023 · 149e8ab · 149e8ab
1 parent 36cfe26
commit 149e8ab
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Showing 2 changed files with 20 additions and 8 deletions.
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp b/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
@@ -3862,12 +3862,9 @@ static unsigned inverseMinMax(unsigned Opc) {
   }
 }
 
-SDValue AMDGPUTargetLowering::performFNegCombine(SDNode *N,
-                                                 DAGCombinerInfo &DCI) const {
-  SelectionDAG &DAG = DCI.DAG;
-  SDValue N0 = N->getOperand(0);
-  EVT VT = N->getValueType(0);
-
+/// \return true if it's profitable to try to push an fneg into its source
+/// instruction.
+bool AMDGPUTargetLowering::shouldFoldFNegIntoSrc(SDNode *N, SDValue N0) {
   unsigned Opc = N0.getOpcode();
 
   // If the input has multiple uses and we can either fold the negate down, or
@@ -3878,13 +3875,27 @@ SDValue AMDGPUTargetLowering::performFNegCombine(SDNode *N,
     // This may be able to fold into the source, but at a code size cost. Don't
     // fold if the fold into the user is free.
     if (allUsesHaveSourceMods(N, 0))
-      return SDValue();
+      return false;
   } else {
     if (fnegFoldsIntoOp(Opc) &&
         (allUsesHaveSourceMods(N) || !allUsesHaveSourceMods(N0.getNode())))
-      return SDValue();
+      return false;
   }
 
+  return true;
+}
+
+SDValue AMDGPUTargetLowering::performFNegCombine(SDNode *N,
+                                                 DAGCombinerInfo &DCI) const {
+  SelectionDAG &DAG = DCI.DAG;
+  SDValue N0 = N->getOperand(0);
+  EVT VT = N->getValueType(0);
+
+  unsigned Opc = N0.getOpcode();
+
+  if (!shouldFoldFNegIntoSrc(N, N0))
+    return SDValue();
+
   SDLoc SL(N);
   switch (Opc) {
   case ISD::FADD: {

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.h b/llvm/lib/Target/AMDGPU/AMDGPUISelLowering.h
@@ -156,6 +156,7 @@ class AMDGPUTargetLowering : public TargetLowering {
     return Val.getOpcode() == ISD::BITCAST ? Val.getOperand(0) : Val;
   }
 
+  static bool shouldFoldFNegIntoSrc(SDNode *FNeg, SDValue FNegSrc);
   static bool allUsesHaveSourceMods(const SDNode *N,
                                     unsigned CostThreshold = 4);
   bool isFAbsFree(EVT VT) const override;