[SamplePGO] Minor efficiency improvement in samplePGO ICP

teresajohnson · teresajohnson · commit 4bdf82ce7990 · 2019-02-05T00:18:38.000Z
Summary: When attaching prof metadata to promoted direct calls in SamplePGO mode, no need to construct and use a SmallVector to pass a single count to the ArrayRef parameter, we can simply use a brace-enclosed init list. This made a small but consistent improvement for a ThinLTO backend compile I was measuring. Reviewers: wmi Subscribers: mehdi_amini, dexonsmith, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D57706 llvm-svn: 353123
diff --git a/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp b/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
@@ -310,10 +310,10 @@ Instruction *llvm::pgo::promoteIndirectCall(Instruction *Inst,
       promoteCallWithIfThenElse(CallSite(Inst), DirectCallee, BranchWeights);
 
   if (AttachProfToDirectCall) {
-    SmallVector<uint32_t, 1> Weights;
-    Weights.push_back(Count);
     MDBuilder MDB(NewInst->getContext());
-    NewInst->setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
+    NewInst->setMetadata(
+        LLVMContext::MD_prof,
+        MDB.createBranchWeights({static_cast<uint32_t>(Count)}));
   }
 
   using namespace ore;
