[llvm] [LTO] Introduce new type alias ImportListsTy (NFC) (PR #106420)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/106420

The background is as follows.  I'm planning to reduce the memory
footprint of ThinLTO indexing by changing ImportMapTy, the data
structure used for an import list.  Once this patch lands, I'm
planning to change the type slightly.  The new type alias allows us to
update the type without touching many places.


>From 1ea65d9a37990a4f08fce100dbcbbbc591dc8f96 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Tue, 27 Aug 2024 22:27:34 -0700
Subject: [PATCH] [LTO] Introduce new type alias ImportListsTy (NFC)

The background is as follows.  I'm planning to reduce the memory
footprint of ThinLTO indexing by changing ImportMapTy, the data
structure used for an import list.  Once this patch lands, I'm
planning to change the type slightly.  The new type alias allows us to
update the type without touching many places.
---
 llvm/include/llvm/Transforms/IPO/FunctionImport.h |  5 ++++-
 llvm/lib/LTO/LTO.cpp                              |  3 +--
 llvm/lib/LTO/ThinLTOCodeGenerator.cpp             | 12 ++++++------
 llvm/lib/Transforms/IPO/FunctionImport.cpp        |  4 ++--
 4 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/llvm/include/llvm/Transforms/IPO/FunctionImport.h b/llvm/include/llvm/Transforms/IPO/FunctionImport.h
index b5b969220df85b..c06d96bbe62e22 100644
--- a/llvm/include/llvm/Transforms/IPO/FunctionImport.h
+++ b/llvm/include/llvm/Transforms/IPO/FunctionImport.h
@@ -149,6 +149,9 @@ class FunctionImporter {
     ImportMapTyImpl ImportMap;
   };
 
+  // A map from destination modules to lists of imports.
+  using ImportListsTy = DenseMap<StringRef, ImportMapTy>;
+
   /// The set contains an entry for every global value that the module exports.
   /// Depending on the user context, this container is allowed to contain
   /// definitions, declarations or a mix of both.
@@ -211,7 +214,7 @@ void ComputeCrossModuleImport(
     const DenseMap<StringRef, GVSummaryMapTy> &ModuleToDefinedGVSummaries,
     function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
         isPrevailing,
-    DenseMap<StringRef, FunctionImporter::ImportMapTy> &ImportLists,
+    FunctionImporter::ImportListsTy &ImportLists,
     DenseMap<StringRef, FunctionImporter::ExportSetTy> &ExportLists);
 
 /// PrevailingType enum used as a return type of callback passed
diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index bd031338e8f39b..09dfec03cb0c34 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -1716,8 +1716,7 @@ Error LTO::runThinLTO(AddStreamFn AddStream, FileCache Cache,
   // Synthesize entry counts for functions in the CombinedIndex.
   computeSyntheticCounts(ThinLTO.CombinedIndex);
 
-  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists(
-      ThinLTO.ModuleMap.size());
+  FunctionImporter::ImportListsTy ImportLists(ThinLTO.ModuleMap.size());
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists(
       ThinLTO.ModuleMap.size());
   StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>> ResolvedODR;
diff --git a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
index f74202781a5f4b..9d5a62fe10c8d7 100644
--- a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -693,7 +693,7 @@ void ThinLTOCodeGenerator::promote(Module &TheModule, ModuleSummaryIndex &Index,
   computePrevailingCopies(Index, PrevailingCopy);
 
   // Generate import/export list
-  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
+  FunctionImporter::ImportListsTy ImportLists(ModuleCount);
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries,
                            IsPrevailing(PrevailingCopy), ImportLists,
@@ -745,7 +745,7 @@ void ThinLTOCodeGenerator::crossModuleImport(Module &TheModule,
   computePrevailingCopies(Index, PrevailingCopy);
 
   // Generate import/export list
-  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
+  FunctionImporter::ImportListsTy ImportLists(ModuleCount);
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries,
                            IsPrevailing(PrevailingCopy), ImportLists,
@@ -785,7 +785,7 @@ void ThinLTOCodeGenerator::gatherImportedSummariesForModule(
   computePrevailingCopies(Index, PrevailingCopy);
 
   // Generate import/export list
-  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
+  FunctionImporter::ImportListsTy ImportLists(ModuleCount);
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries,
                            IsPrevailing(PrevailingCopy), ImportLists,
@@ -823,7 +823,7 @@ void ThinLTOCodeGenerator::emitImports(Module &TheModule, StringRef OutputName,
   computePrevailingCopies(Index, PrevailingCopy);
 
   // Generate import/export list
-  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
+  FunctionImporter::ImportListsTy ImportLists(ModuleCount);
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries,
                            IsPrevailing(PrevailingCopy), ImportLists,
@@ -874,7 +874,7 @@ void ThinLTOCodeGenerator::internalize(Module &TheModule,
   computePrevailingCopies(Index, PrevailingCopy);
 
   // Generate import/export list
-  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
+  FunctionImporter::ImportListsTy ImportLists(ModuleCount);
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries,
                            IsPrevailing(PrevailingCopy), ImportLists,
@@ -1074,7 +1074,7 @@ void ThinLTOCodeGenerator::run() {
 
   // Collect the import/export lists for all modules from the call-graph in the
   // combined index.
-  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
+  FunctionImporter::ImportListsTy ImportLists(ModuleCount);
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(*Index, ModuleToDefinedGVSummaries,
                            IsPrevailing(PrevailingCopy), ImportLists,
diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index 512f771a873aa1..6227b085f13a60 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -1111,7 +1111,7 @@ collectImportStatistics(const ModuleSummaryIndex &Index,
 #ifndef NDEBUG
 static bool checkVariableImport(
     const ModuleSummaryIndex &Index,
-    DenseMap<StringRef, FunctionImporter::ImportMapTy> &ImportLists,
+    FunctionImporter::ImportListsTy &ImportLists,
     DenseMap<StringRef, FunctionImporter::ExportSetTy> &ExportLists) {
   DenseSet<GlobalValue::GUID> FlattenedImports;
 
@@ -1152,7 +1152,7 @@ void llvm::ComputeCrossModuleImport(
     const DenseMap<StringRef, GVSummaryMapTy> &ModuleToDefinedGVSummaries,
     function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
         isPrevailing,
-    DenseMap<StringRef, FunctionImporter::ImportMapTy> &ImportLists,
+    FunctionImporter::ImportListsTy &ImportLists,
     DenseMap<StringRef, FunctionImporter::ExportSetTy> &ExportLists) {
   auto MIS = ModuleImportsManager::create(isPrevailing, Index, &ExportLists);
   // For each module that has function defined, compute the import/export lists.