2 files changed, 13 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 1c60237f75b..c32412a741c 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -12818,6 +12818,16 @@ SDValue X86TargetLowering::getRecipEstimate(SDValue Op,
   return SDValue();
 }
 
+/// If we have at least two divisions that use the same divisor, convert to
+/// multplication by a reciprocal. This may need to be adjusted for a given
+/// CPU if a division's cost is not at least twice the cost of a multiplication.
+/// This is because we still need one division to calculate the reciprocal and
+/// then we need two multiplies by that reciprocal as replacements for the
+/// original divisions.
+bool X86TargetLowering::combineRepeatedFPDivisors(unsigned NumUsers) const {
+  return NumUsers > 1;
+}
+
 static bool isAllOnes(SDValue V) {
   ConstantSDNode *C = dyn_cast<ConstantSDNode>(V);
   return C && C->isAllOnesValue();
diff --git a/llvm/lib/Target/X86/X86ISelLowering.h b/llvm/lib/Target/X86/X86ISelLowering.h
index dd20ec23976..5130c37b042 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.h
+++ b/llvm/lib/Target/X86/X86ISelLowering.h
@@ -1072,6 +1072,9 @@ namespace llvm {
     /// Use rcp* to speed up fdiv calculations.
     SDValue getRecipEstimate(SDValue Operand, DAGCombinerInfo &DCI,
                              unsigned &RefinementSteps) const override;
+
+    /// Reassociate floating point divisions into multiply by reciprocal.
+    bool combineRepeatedFPDivisors(unsigned NumUsers) const override;
   };
 
   namespace X86 {