[Transforms] Avoid repeated hash lookups (NFC) (#110400)

Author: kazutakahirata

llvm/include/llvm/Transforms/Utils/SampleProfileInference.h

@@ -247,9 +247,10 @@ FlowFunction SampleProfileInference<BT>::createFlowFunction(
   // Create FlowBlocks
   for (const auto *BB : BasicBlocks) {
     FlowBlock Block;
-    if (SampleBlockWeights.contains(BB)) {
+    auto It = SampleBlockWeights.find(BB);
+    if (It != SampleBlockWeights.end()) {
       Block.HasUnknownWeight = false;
-      Block.Weight = SampleBlockWeights[BB];
+      Block.Weight = It->second;
     } else {
       Block.HasUnknownWeight = true;
       Block.Weight = 0;