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[IPO] Avoid repeated hash lookups (NFC) #130708

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kazutakahirata
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@kazutakahirata kazutakahirata requested a review from nikic March 11, 2025 03:41
@llvmbot llvmbot added PGO Profile Guided Optimizations llvm:transforms labels Mar 11, 2025
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llvmbot commented Mar 11, 2025

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-pgo

Author: Kazu Hirata (kazutakahirata)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/130708.diff

1 Files Affected:

  • (modified) llvm/lib/Transforms/IPO/SampleProfileProbe.cpp (+3-2)
diff --git a/llvm/lib/Transforms/IPO/SampleProfileProbe.cpp b/llvm/lib/Transforms/IPO/SampleProfileProbe.cpp
index ec2594b0d9dc1..e40b2cdc37f70 100644
--- a/llvm/lib/Transforms/IPO/SampleProfileProbe.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfileProbe.cpp
@@ -148,7 +148,8 @@ void PseudoProbeVerifier::verifyProbeFactors(
   auto &PrevProbeFactors = FunctionProbeFactors[F->getName()];
   for (const auto &I : ProbeFactors) {
     float CurProbeFactor = I.second;
-    if (PrevProbeFactors.count(I.first)) {
+    auto [It, Inserted] = PrevProbeFactors.try_emplace(I.first);
+    if (!Inserted) {
       float PrevProbeFactor = PrevProbeFactors[I.first];
       if (std::abs(CurProbeFactor - PrevProbeFactor) >
           DistributionFactorVariance) {
@@ -163,7 +164,7 @@ void PseudoProbeVerifier::verifyProbeFactors(
     }
 
     // Update
-    PrevProbeFactors[I.first] = I.second;
+    It->second = I.second;
   }
 }
 

@kazutakahirata kazutakahirata changed the title [Transforms] Avoid repeated hash lookups (NFC) [IPO] Avoid repeated hash lookups (NFC) Mar 11, 2025
@kazutakahirata kazutakahirata merged commit 72aec1d into llvm:main Mar 11, 2025
11 checks passed
@kazutakahirata kazutakahirata deleted the cleanup_001_repeated_hash_lookups_llvm_IPO branch March 11, 2025 23:31
Bertik23 pushed a commit to Bertik23/llvm-project that referenced this pull request Mar 12, 2025
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3 participants