[clang] 835fcf2 - [clang][deps] Make order of module dependencies deterministic

[Ben Langmuir via cfe-commits]

Author: Ben Langmuir
Date: 2022-06-08T11:09:17-07:00
New Revision: 835fcf2aa5127bf99a1e6397c72153f00a0497b2

URL: https://github.com/llvm/llvm-project/commit/835fcf2aa5127bf99a1e6397c72153f00a0497b2
DIFF: https://github.com/llvm/llvm-project/commit/835fcf2aa5127bf99a1e6397c72153f00a0497b2.diff

LOG: [clang][deps] Make order of module dependencies deterministic

This fixes the underlying module dependencies, which had a
non-deterministic order, which was also visible in the order of calls to
DependencyConsumer methods. This was not directly observable in
the clang-scan-deps utility, because it was previously seeing a sorted
order from std::map in DependencyScanningTool. However, the underlying
API previously created a likely issue for any other clients. Note: if
you only apply the change from DependencyScanningTool, you can see the
issue in clang-scan-deps, and existing tests will fail
non-deterministicaly.

Differential Revision: https://reviews.llvm.org/D127243

Added: 
    

Modified: 
    clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h
    clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp
    clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h b/clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h
index 363e159dd990f..e0a4d6a554eb2 100644
--- a/clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h
+++ b/clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h
@@ -149,9 +149,9 @@ class ModuleDepCollectorPP final : public PPCallbacks {
   /// The parent dependency collector.
   ModuleDepCollector &MDC;
   /// Working set of direct modular dependencies.
-  llvm::DenseSet<const Module *> DirectModularDeps;
+  llvm::SetVector<const Module *> DirectModularDeps;
   /// Working set of direct modular dependencies that have already been built.
-  llvm::DenseSet<const Module *> DirectPrebuiltModularDeps;
+  llvm::SetVector<const Module *> DirectPrebuiltModularDeps;
 
   void handleImport(const Module *Imported);
 
@@ -199,7 +199,7 @@ class ModuleDepCollector final : public DependencyCollector {
   /// textually included header files.
   std::vector<std::string> FileDeps;
   /// Direct and transitive modular dependencies of the main source file.
-  std::unordered_map<const Module *, ModuleDeps> ModularDeps;
+  llvm::MapVector<const Module *, std::unique_ptr<ModuleDeps>> ModularDeps;
   /// Options that control the dependency output generation.
   std::unique_ptr<DependencyOutputOptions> Opts;
   /// The original Clang invocation passed to dependency scanner.

diff  --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp
index 6fd3a83fd3f7b..5041a8eb6e597 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningTool.cpp
@@ -176,7 +176,7 @@ DependencyScanningTool::getFullDependencies(
   private:
     std::vector<std::string> Dependencies;
     std::vector<PrebuiltModuleDep> PrebuiltModuleDeps;
-    std::map<std::string, ModuleDeps> ClangModuleDeps;
+    llvm::MapVector<std::string, ModuleDeps, llvm::StringMap<unsigned>> ClangModuleDeps;
     std::string ContextHash;
     std::vector<std::string> OutputPaths;
     const llvm::StringSet<> &AlreadySeen;

diff  --git a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
index 21a422f8dbbae..6c7fdbc3944a6 100644
--- a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
+++ b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
@@ -199,7 +199,7 @@ void ModuleDepCollectorPP::EndOfMainFile() {
   MDC.Consumer.handleDependencyOutputOpts(*MDC.Opts);
 
   for (auto &&I : MDC.ModularDeps)
-    MDC.Consumer.handleModuleDependency(I.second);
+    MDC.Consumer.handleModuleDependency(*I.second);
 
   for (auto &&I : MDC.FileDeps)
     MDC.Consumer.handleFileDependency(I);
@@ -212,11 +212,12 @@ ModuleID ModuleDepCollectorPP::handleTopLevelModule(const Module *M) {
   assert(M == M->getTopLevelModule() && "Expected top level module!");
 
   // If this module has been handled already, just return its ID.
-  auto ModI = MDC.ModularDeps.insert({M, ModuleDeps{}});
+  auto ModI = MDC.ModularDeps.insert({M, nullptr});
   if (!ModI.second)
-    return ModI.first->second.ID;
+    return ModI.first->second->ID;
 
-  ModuleDeps &MD = ModI.first->second;
+  ModI.first->second = std::make_unique<ModuleDeps>();
+  ModuleDeps &MD = *ModI.first->second;
 
   MD.ID.ModuleName = M->getFullModuleName();
   MD.ImportedByMainFile = DirectModularDeps.contains(M);