[llvm] [FuncSpec] Only compute Latency bonus when necessary (PR #113159)

[Alexandros Lamprineas via llvm-commits]

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@@ -875,48 +909,67 @@ bool FunctionSpecializer::findSpecializations(Function *F, unsigned FuncSize,
       AllSpecs[Index].CallSites.push_back(&CS);
     } else {
       // Calculate the specialisation gain.
-      Bonus B;
+      Cost CodeSize;
       unsigned Score = 0;
       InstCostVisitor Visitor = getInstCostVisitorFor(F);
       for (ArgInfo &A : S.Args) {
-        B += Visitor.getSpecializationBonus(A.Formal, A.Actual);
+        CodeSize += Visitor.getCodeSizeSavingsForArg(A.Formal, A.Actual);
         Score += getInliningBonus(A.Formal, A.Actual);
       }
-      B += Visitor.getBonusFromPendingPHIs();
-
+      CodeSize += Visitor.getCodeSizeSavingsFromPendingPHIs();
 
-      LLVM_DEBUG(dbgs() << "FnSpecialization: Specialization bonus {CodeSize = "
-                        << B.CodeSize << ", Latency = " << B.Latency
-                        << ", Inlining = " << Score << "}\n");
-
-      FunctionGrowth[F] += FuncSize - B.CodeSize;
-
-      auto IsProfitable = [](Bonus &B, unsigned Score, unsigned FuncSize,
-                             unsigned FuncGrowth) -> bool {
+      auto IsProfitable = [&]() -> bool {
         // No check required.
         if (ForceSpecialization)
           return true;
+
+        unsigned CodeSizeSavings = getCostValue(CodeSize);
+        // TODO: We should only accumulate codesize increase of specializations
+        // that are actually created.
+        FunctionGrowth[F] += FuncSize - CodeSizeSavings;
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labrinea wrote:

Fair enough, it alredy an improvement and the problem you spotted is not introduced by this patch. Good we have a TODO.

https://github.com/llvm/llvm-project/pull/113159