[llvm][Inline] Add interface to return cost-benefit stuff

Return cost-benefit stuff which is computed by cost-benefit analysis.

Reviewed By: mtrofin

Differential Revision: https://reviews.llvm.org/D105349

include/llvm/Analysis/InlineCost.h

@@ -55,6 +55,22 @@ const unsigned TotalAllocaSizeRecursiveCaller = 1024;
 const uint64_t MaxSimplifiedDynamicAllocaToInline = 65536;
 } // namespace InlineConstants
 
+// The cost-benefit pair computed by cost-benefit analysis.
+class CostBenefitPair {
+public:
+  CostBenefitPair(APInt Cost, APInt Benefit) : Cost(Cost), Benefit(Benefit) {}
+  CostBenefitPair(const CostBenefitPair &CBP)
+      : Cost(CBP.getCost()), Benefit(CBP.getBenefit()) {}
+
+  const APInt &getCost() const { return Cost; }
+
+  const APInt &getBenefit() const { return Benefit; }
+
+private:
+  APInt Cost;
+  APInt Benefit;
+};
+
 /// Represents the cost of inlining a function.
 ///
 /// This supports special values for functions which should "always" or
@@ -77,9 +93,14 @@ class InlineCost {
   /// Must be set for Always and Never instances.
   const char *Reason = nullptr;
 
+  /// The cost-benefit pair computed by cost-benefit analysis.
+  Optional<CostBenefitPair> CostBenefit = None;
+
   // Trivial constructor, interesting logic in the factory functions below.
-  InlineCost(int Cost, int Threshold, const char *Reason = nullptr)
-      : Cost(Cost), Threshold(Threshold), Reason(Reason) {
+  InlineCost(int Cost, int Threshold, const char *Reason = nullptr,
+             Optional<CostBenefitPair> CostBenefit = None)
+      : Cost(Cost), Threshold(Threshold), Reason(Reason),
+        CostBenefit(CostBenefit) {
     assert((isVariable() || Reason) &&
            "Reason must be provided for Never or Always");
   }
@@ -90,11 +111,13 @@ public:
     assert(Cost < NeverInlineCost && "Cost crosses sentinel value");
     return InlineCost(Cost, Threshold);
   }
-  static InlineCost getAlways(const char *Reason) {
-    return InlineCost(AlwaysInlineCost, 0, Reason);
+  static InlineCost getAlways(const char *Reason,
+                              Optional<CostBenefitPair> CostBenefit = None) {
+    return InlineCost(AlwaysInlineCost, 0, Reason, CostBenefit);
   }
-  static InlineCost getNever(const char *Reason) {
-    return InlineCost(NeverInlineCost, 0, Reason);
+  static InlineCost getNever(const char *Reason,
+                             Optional<CostBenefitPair> CostBenefit = None) {
+    return InlineCost(NeverInlineCost, 0, Reason, CostBenefit);
   }
 
   /// Test whether the inline cost is low enough for inlining.
@@ -117,6 +140,9 @@ public:
     return Threshold;
   }
 
+  /// Get the cost-benefit pair which was computed by cost-benefit analysis
+  Optional<CostBenefitPair> getCostBenefit() const { return CostBenefit; }
+
   /// Get the reason of Always or Never.
   const char *getReason() const {
     assert((Reason || isVariable()) &&

lib/Analysis/InlineCost.cpp

@@ -509,6 +509,9 @@ class InlineCostCallAnalyzer final : public CallAnalyzer {
   // Whether inlining is decided by cost-benefit analysis.
   bool DecidedByCostBenefit = false;
 
+  // The cost-benefit pair computed by cost-benefit analysis.
+  Optional<CostBenefitPair> CostBenefit = None;
+
   bool SingleBB = true;
 
   unsigned SROACostSavings = 0;
@@ -794,6 +797,8 @@ class InlineCostCallAnalyzer final : public CallAnalyzer {
     // savings threshold.
     Size = Size > InlineSizeAllowance ? Size - InlineSizeAllowance : 1;
 
+    CostBenefit.emplace(APInt(128, Size), CycleSavings);
+
     // Return true if the savings justify the cost of inlining.  Specifically,
     // we evaluate the following inequality:
     //
@@ -941,6 +946,7 @@ public:
   virtual ~InlineCostCallAnalyzer() {}
   int getThreshold() const { return Threshold; }
   int getCost() const { return Cost; }
+  Optional<CostBenefitPair> getCostBenefitPair() { return CostBenefit; }
   bool wasDecidedByCostBenefit() const { return DecidedByCostBenefit; }
 };
 
@@ -2834,9 +2840,10 @@ InlineCost llvm::getInlineCost(
   // as it's not what drives cost-benefit analysis.
   if (CA.wasDecidedByCostBenefit()) {
     if (ShouldInline.isSuccess())
-      return InlineCost::getAlways("benefit over cost");
+      return InlineCost::getAlways("benefit over cost",
+                                   CA.getCostBenefitPair());
     else
-      return InlineCost::getNever("cost over benefit");
+      return InlineCost::getNever("cost over benefit", CA.getCostBenefitPair());
   }
 
   // Check if there was a reason to force inlining or no inlining.