[llvm-mca] Avoid repeated hash lookups (NFC)

[kazutakahirata]

No description provided.

[llvmbot]

@llvm/pr-subscribers-tools-llvm-mca

Author: Kazu Hirata (kazutakahirata)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/129656.diff

1 Files Affected:

• (modified) llvm/tools/llvm-mca/CodeRegion.cpp (+2-3)

diff --git a/llvm/tools/llvm-mca/CodeRegion.cpp b/llvm/tools/llvm-mca/CodeRegion.cpp
index ba5188076c2e7..eacbc062cb113 100644
--- a/llvm/tools/llvm-mca/CodeRegion.cpp
+++ b/llvm/tools/llvm-mca/CodeRegion.cpp
@@ -123,8 +123,8 @@ void InstrumentRegions::beginRegion(StringRef Description, SMLoc Loc,
     return;
   }
 
-  auto It = ActiveRegions.find(Description);
-  if (It != ActiveRegions.end()) {
+  auto [It, Inserted] = ActiveRegions.try_emplace(Description, Regions.size());
+  if (!Inserted) {
     const CodeRegion &R = *Regions[It->second];
     SM.PrintMessage(
         Loc, llvm::SourceMgr::DK_Error,
@@ -136,7 +136,6 @@ void InstrumentRegions::beginRegion(StringRef Description, SMLoc Loc,
     return;
   }
 
-  ActiveRegions[Description] = Regions.size();
   Regions.emplace_back(
       std::make_unique<InstrumentRegion>(Description, Loc, std::move(I)));
 }