[Mlir-commits] [mlir] [mlir] Use *Map::try_emplace (NFC) (PR #143341)

[Kazu Hirata]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/143341

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


>From b71c6524c5dca9566871e431de9a2c2816a34b14 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Sun, 8 Jun 2025 16:35:15 -0700
Subject: [PATCH] [mlir] Use *Map::try_emplace (NFC)

- try_emplace(Key) is shorter than insert({Key, nullptr}).
- try_emplace performs value initialization without value parameters.
- We overwrite values on successful insertion anyway.
---
 .../mlir/Debug/BreakpointManagers/TagBreakpointManager.h     | 2 +-
 mlir/lib/Bytecode/Writer/IRNumbering.cpp                     | 4 ++--
 mlir/lib/IR/MLIRContext.cpp                                  | 2 +-
 mlir/lib/Target/LLVMIR/LoopAnnotationTranslation.cpp         | 2 +-
 mlir/lib/Transforms/Utils/CFGToSCF.cpp                       | 5 ++---
 mlir/lib/Transforms/Utils/Inliner.cpp                        | 2 +-
 6 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/mlir/include/mlir/Debug/BreakpointManagers/TagBreakpointManager.h b/mlir/include/mlir/Debug/BreakpointManagers/TagBreakpointManager.h
index 85fdb9a63286a..af138da84e028 100644
--- a/mlir/include/mlir/Debug/BreakpointManagers/TagBreakpointManager.h
+++ b/mlir/include/mlir/Debug/BreakpointManagers/TagBreakpointManager.h
@@ -48,7 +48,7 @@ class TagBreakpointManager
   /// If a breakpoint already exists for the given tag, return the existing
   /// instance.
   TagBreakpoint *addBreakpoint(StringRef tag) {
-    auto result = breakpoints.insert({tag, nullptr});
+    auto result = breakpoints.try_emplace(tag);
     auto &it = result.first;
     if (result.second)
       it->second = std::make_unique<TagBreakpoint>(tag.str());
diff --git a/mlir/lib/Bytecode/Writer/IRNumbering.cpp b/mlir/lib/Bytecode/Writer/IRNumbering.cpp
index 1bc02e1721573..8e8e7148ee70e 100644
--- a/mlir/lib/Bytecode/Writer/IRNumbering.cpp
+++ b/mlir/lib/Bytecode/Writer/IRNumbering.cpp
@@ -308,7 +308,7 @@ void IRNumberingState::computeGlobalNumberingState(Operation *rootOp) {
 }
 
 void IRNumberingState::number(Attribute attr) {
-  auto it = attrs.insert({attr, nullptr});
+  auto it = attrs.try_emplace(attr);
   if (!it.second) {
     ++it.first->second->refCount;
     return;
@@ -475,7 +475,7 @@ void IRNumberingState::number(OperationName opName) {
 }
 
 void IRNumberingState::number(Type type) {
-  auto it = types.insert({type, nullptr});
+  auto it = types.try_emplace(type);
   if (!it.second) {
     ++it.first->second->refCount;
     return;
diff --git a/mlir/lib/IR/MLIRContext.cpp b/mlir/lib/IR/MLIRContext.cpp
index 2ab6b6189b438..ce5e63a32dc72 100644
--- a/mlir/lib/IR/MLIRContext.cpp
+++ b/mlir/lib/IR/MLIRContext.cpp
@@ -810,7 +810,7 @@ OperationName::OperationName(StringRef name, MLIRContext *context) {
   // Acquire a writer-lock so that we can safely create the new instance.
   ScopedWriterLock lock(ctxImpl.operationInfoMutex, isMultithreadingEnabled);
 
-  auto it = ctxImpl.operations.insert({name, nullptr});
+  auto it = ctxImpl.operations.try_emplace(name);
   if (it.second) {
     auto nameAttr = StringAttr::get(context, name);
     it.first->second = std::make_unique<UnregisteredOpModel>(
diff --git a/mlir/lib/Target/LLVMIR/LoopAnnotationTranslation.cpp b/mlir/lib/Target/LLVMIR/LoopAnnotationTranslation.cpp
index 1dde457b5c34f..54ae01c77c445 100644
--- a/mlir/lib/Target/LLVMIR/LoopAnnotationTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/LoopAnnotationTranslation.cpp
@@ -280,7 +280,7 @@ LoopAnnotationTranslation::translateLoopAnnotation(LoopAnnotationAttr attr,
 llvm::MDNode *
 LoopAnnotationTranslation::getAccessGroup(AccessGroupAttr accessGroupAttr) {
   auto [result, inserted] =
-      accessGroupMetadataMapping.insert({accessGroupAttr, nullptr});
+      accessGroupMetadataMapping.try_emplace(accessGroupAttr);
   if (inserted)
     result->second = llvm::MDNode::getDistinct(llvmModule.getContext(), {});
   return result->second;
diff --git a/mlir/lib/Transforms/Utils/CFGToSCF.cpp b/mlir/lib/Transforms/Utils/CFGToSCF.cpp
index eefdf1d4e393a..de380fc325f55 100644
--- a/mlir/lib/Transforms/Utils/CFGToSCF.cpp
+++ b/mlir/lib/Transforms/Utils/CFGToSCF.cpp
@@ -427,8 +427,7 @@ class ReturnLikeExitCombiner {
   /// region with an instance of `returnLikeOp`s kind.
   void combineExit(Operation *returnLikeOp,
                    function_ref<Value(unsigned)> getSwitchValue) {
-    auto [iter, inserted] =
-        returnLikeToCombinedExit.insert({returnLikeOp, nullptr});
+    auto [iter, inserted] = returnLikeToCombinedExit.try_emplace(returnLikeOp);
     if (!inserted && iter->first == returnLikeOp)
       return;
 
@@ -1284,7 +1283,7 @@ FailureOr<bool> mlir::transformCFGToSCF(Region &region,
 
   DenseMap<Type, Value> typedUndefCache;
   auto getUndefValue = [&](Type type) {
-    auto [iter, inserted] = typedUndefCache.insert({type, nullptr});
+    auto [iter, inserted] = typedUndefCache.try_emplace(type);
     if (!inserted)
       return iter->second;
 
diff --git a/mlir/lib/Transforms/Utils/Inliner.cpp b/mlir/lib/Transforms/Utils/Inliner.cpp
index 54b5c788a3526..ae34c4ad49e24 100644
--- a/mlir/lib/Transforms/Utils/Inliner.cpp
+++ b/mlir/lib/Transforms/Utils/Inliner.cpp
@@ -45,7 +45,7 @@ static void walkReferencedSymbolNodes(
 
   Operation *symbolTableOp = op->getParentOp();
   for (const SymbolTable::SymbolUse &use : *symbolUses) {
-    auto refIt = resolvedRefs.insert({use.getSymbolRef(), nullptr});
+    auto refIt = resolvedRefs.try_emplace(use.getSymbolRef());
     CallGraphNode *&node = refIt.first->second;
 
     // If this is the first instance of this reference, try to resolve a