[llvm] Use *Map::try_emplace (NFC)#149257

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kazutakahirata merged 1 commit intollvm:mainfromkazutakahirata:cleanup_20250716_try_emplace_llvm

Jul 17, 2025

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[llvm] Use *Map::try_emplace (NFC)#149257

kazutakahirata merged 1 commit intollvm:mainfromkazutakahirata:cleanup_20250716_try_emplace_llvm

Jul 17, 2025

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kazutakahirata commentedJul 17, 2025

try_emplace(Key) is shorter than insert({Key, nullptr}).
try_emplace performs value initialization without value parameters.
We overwrite values on successful insertion anyway.

While we are at it, this patch simplifies the code with structured
binding.

[llvm] Use *Map::try_emplace (NFC)

62860e7

- try_emplace(Key) is shorter than insert({Key, nullptr}).- try_emplace performs value initialization without value parameters.- We overwrite values on successful insertion anyway.While we are at it, this patch simplifies the code with structuredbinding.

kazutakahirata requested review fromarsenm,shiltian andtgymnich

July 17, 2025 05:42

llvmbot added mc

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Jul 17, 2025

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llvmbot commentedJul 17, 2025•
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Author: Kazu Hirata (kazutakahirata)

Changes

try_emplace(Key) is shorter than insert({Key, nullptr}).
try_emplace performs value initialization without value parameters.
We overwrite values on successful insertion anyway.

While we are at it, this patch simplifies the code with structured
binding.

Full diff:https://github.com/llvm/llvm-project/pull/149257.diff

2 Files Affected:

(modified) llvm/include/llvm/ADT/EquivalenceClasses.h (+4-4)
(modified) llvm/lib/MC/MCContext.cpp (+2-3)

diff --git a/llvm/include/llvm/ADT/EquivalenceClasses.h b/llvm/include/llvm/ADT/EquivalenceClasses.hindex b1009f8b49992..1a2331c1a0322 100644--- a/llvm/include/llvm/ADT/EquivalenceClasses.h+++ b/llvm/include/llvm/ADT/EquivalenceClasses.h@@ -218,12 +218,12 @@ template <class ElemTy> class EquivalenceClasses {   /// insert - Insert a new value into the union/find set, ignoring the request   /// if the value already exists.   const ECValue &insert(const ElemTy &Data) {-    auto I = TheMapping.insert({Data, nullptr});-    if (!I.second)-      return *I.first->second;+    auto [I, Inserted] = TheMapping.try_emplace(Data);+    if (!Inserted)+      return *I->second;      auto *ECV = new (ECValueAllocator) ECValue(Data);-    I.first->second = ECV;+    I->second = ECV;     Members.push_back(ECV);     return *ECV;   }diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cppindex 070be621a4b2c..12b3fbab8fb8f 100644--- a/llvm/lib/MC/MCContext.cpp+++ b/llvm/lib/MC/MCContext.cpp@@ -734,9 +734,8 @@ MCSectionGOFF *MCContext::getGOFFSection(SectionKind Kind, StringRef Name,       UniqueName.append("/").append(P->getName());   }   // Do the lookup. If we don't have a hit, return a new section.-  auto IterBool = GOFFUniquingMap.insert(std::make_pair(UniqueName, nullptr));-  auto Iter = IterBool.first;-  if (!IterBool.second)+  auto [Iter, Inserted] = GOFFUniquingMap.try_emplace(UniqueName);+  if (!Inserted)     return Iter->second;    StringRef CachedName = StringRef(Iter->first.c_str(), Name.size());