From 8bbd0797d4b8aa1d993f587eb2dfd9a89df1f406 Mon Sep 17 00:00:00 2001
From: Jan Svoboda <jan_svoboda@apple.com>
Date: Tue, 22 Oct 2024 08:57:33 -0700
Subject: [clang] Allocate `Module` instances in `BumpPtrAllocator` (#112795)

In `clang-scan-deps`, we're creating lots of `Module` instances.
Allocating them all in a bump-pointer allocator reduces the number of
retired instructions by 1-1.5% on my workload.
---
 clang/lib/Basic/Module.cpp | 26 ++++----------------------
 1 file changed, 4 insertions(+), 22 deletions(-)

(limited to 'clang/lib/Basic/Module.cpp')

diff --git a/clang/lib/Basic/Module.cpp b/clang/lib/Basic/Module.cpp
index fee372b..ad52fcc 100644
--- a/clang/lib/Basic/Module.cpp
+++ b/clang/lib/Basic/Module.cpp
@@ -34,8 +34,9 @@
 
 using namespace clang;
 
-Module::Module(StringRef Name, SourceLocation DefinitionLoc, Module *Parent,
-               bool IsFramework, bool IsExplicit, unsigned VisibilityID)
+Module::Module(ModuleConstructorTag, StringRef Name,
+               SourceLocation DefinitionLoc, Module *Parent, bool IsFramework,
+               bool IsExplicit, unsigned VisibilityID)
     : Name(Name), DefinitionLoc(DefinitionLoc), Parent(Parent),
       VisibilityID(VisibilityID), IsUnimportable(false),
       HasIncompatibleModuleFile(false), IsAvailable(true),
@@ -58,11 +59,7 @@ Module::Module(StringRef Name, SourceLocation DefinitionLoc, Module *Parent,
   }
 }
 
-Module::~Module() {
-  for (auto *Submodule : SubModules) {
-    delete Submodule;
-  }
-}
+Module::~Module() = default;
 
 static bool isPlatformEnvironment(const TargetInfo &Target, StringRef Feature) {
   StringRef Platform = Target.getPlatformName();
@@ -361,21 +358,6 @@ Module *Module::findSubmodule(StringRef Name) const {
   return SubModules[Pos->getValue()];
 }
 
-Module *Module::findOrInferSubmodule(StringRef Name) {
-  llvm::StringMap<unsigned>::const_iterator Pos = SubModuleIndex.find(Name);
-  if (Pos != SubModuleIndex.end())
-    return SubModules[Pos->getValue()];
-  if (!InferSubmodules)
-    return nullptr;
-  Module *Result = new Module(Name, SourceLocation(), this, false, InferExplicitSubmodules, 0);
-  Result->InferExplicitSubmodules = InferExplicitSubmodules;
-  Result->InferSubmodules = InferSubmodules;
-  Result->InferExportWildcard = InferExportWildcard;
-  if (Result->InferExportWildcard)
-    Result->Exports.push_back(Module::ExportDecl(nullptr, true));
-  return Result;
-}
-
 Module *Module::getGlobalModuleFragment() const {
   assert(isNamedModuleUnit() && "We should only query the global module "
                                 "fragment from the C++20 Named modules");
-- 
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