[llvm] [Analysis] Avoid repeated hash lookups (NFC) (PR #126465)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/126465

None

>From b13a6dc4c2fbd41581aa2578d38b6bfd17a36a2d Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Sun, 9 Feb 2025 13:42:09 -0800
Subject: [PATCH] [Analysis] Avoid repeated hash lookups (NFC)

---
 llvm/include/llvm/Analysis/RegionInfoImpl.h | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/llvm/include/llvm/Analysis/RegionInfoImpl.h b/llvm/include/llvm/Analysis/RegionInfoImpl.h
index db3a9027549cefe..eb99d8bc6fb23ef 100644
--- a/llvm/include/llvm/Analysis/RegionInfoImpl.h
+++ b/llvm/include/llvm/Analysis/RegionInfoImpl.h
@@ -720,16 +720,14 @@ void RegionInfoBase<Tr>::buildRegionsTree(DomTreeNodeT *N, RegionT *region) {
   while (BB == region->getExit())
     region = region->getParent();
 
-  typename BBtoRegionMap::iterator it = BBtoRegion.find(BB);
+  auto [It, Inserted] = BBtoRegion.try_emplace(BB, region);
 
   // This basic block is a start block of a region. It is already in the
   // BBtoRegion relation. Only the child basic blocks have to be updated.
-  if (it != BBtoRegion.end()) {
-    RegionT *newRegion = it->second;
+  if (!Inserted) {
+    RegionT *newRegion = It->second;
     region->addSubRegion(getTopMostParent(newRegion));
     region = newRegion;
-  } else {
-    BBtoRegion[BB] = region;
   }
 
   for (DomTreeNodeBase<BlockT> *C : *N) {