[clang][DependencyScanning] Add API to register callback for cmd transform

Add a callback to allow client to transform build command of the module
through CompilerInvocation interface. This allows API user to modified
the build command to its need with very little cost.

Author: cachemeifyoucan

clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h

@@ -17,6 +17,8 @@
 #include "llvm/CAS/ActionCache.h"
 
 namespace clang {
+class CowCompilerInvocation;
+
 namespace tooling {
 namespace dependencies {
 
@@ -98,13 +100,16 @@ enum class ScanningOptimizations {
 /// is used by the individual dependency scanning workers.
 class DependencyScanningService {
 public:
+  using InvocationCallbackTy = std::function<void(CowCompilerInvocation &)>;
+
   DependencyScanningService(
       ScanningMode Mode, ScanningOutputFormat Format, CASOptions CASOpts,
       std::shared_ptr<llvm::cas::ObjectStore> CAS,
       std::shared_ptr<llvm::cas::ActionCache> Cache,
       IntrusiveRefCntPtr<llvm::cas::CachingOnDiskFileSystem> SharedFS,
       ScanningOptimizations OptimizeArgs = ScanningOptimizations::Default,
-      bool EagerLoadModules = false, bool TraceVFS = false);
+      bool EagerLoadModules = false, bool TraceVFS = false,
+      InvocationCallbackTy TransForm = nullptr);
 
   ScanningMode getMode() const { return Mode; }
 
@@ -133,6 +138,10 @@ class DependencyScanningService {
 
   ModuleCacheMutexes &getModuleCacheMutexes() { return ModCacheMutexes; }
 
+  InvocationCallbackTy getCompilerInvocationTransformation() const {
+    return Transform;
+  }
+
 private:
   const ScanningMode Mode;
   const ScanningOutputFormat Format;
@@ -152,6 +161,8 @@ class DependencyScanningService {
   std::optional<DependencyScanningFilesystemSharedCache> SharedCache;
   /// The global module cache mutexes.
   ModuleCacheMutexes ModCacheMutexes;
+  /// Callback to transform compiler invocation.
+  const InvocationCallbackTy Transform;
 };
 
 } // end namespace dependencies

clang/lib/Tooling/DependencyScanning/DependencyScanningService.cpp

@@ -21,10 +21,12 @@ DependencyScanningService::DependencyScanningService(
     std::shared_ptr<llvm::cas::ObjectStore> CAS,
     std::shared_ptr<llvm::cas::ActionCache> Cache,
     IntrusiveRefCntPtr<llvm::cas::CachingOnDiskFileSystem> SharedFS,
-    ScanningOptimizations OptimizeArgs, bool EagerLoadModules, bool TraceVFS)
-    : Mode(Mode), Format(Format), CASOpts(std::move(CASOpts)), CAS(std::move(CAS)), Cache(std::move(Cache)),
-      OptimizeArgs(OptimizeArgs), EagerLoadModules(EagerLoadModules), TraceVFS(TraceVFS),
-      SharedFS(std::move(SharedFS)) {
+    ScanningOptimizations OptimizeArgs, bool EagerLoadModules, bool TraceVFS,
+    InvocationCallbackTy Transform)
+    : Mode(Mode), Format(Format), CASOpts(std::move(CASOpts)),
+      CAS(std::move(CAS)), Cache(std::move(Cache)), OptimizeArgs(OptimizeArgs),
+      EagerLoadModules(EagerLoadModules), TraceVFS(TraceVFS),
+      SharedFS(std::move(SharedFS)), Transform(Transform) {
   if (!this->SharedFS)
     SharedCache.emplace();
 

clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

@@ -956,9 +956,12 @@ ModuleDepCollectorPP::handleTopLevelModule(const Module *M) {
   // Finish the compiler invocation. Requires dependencies and the context hash.
   MDC.addOutputPaths(CI, MD);
 
+  if (auto Transform = MDC.Service.getCompilerInvocationTransformation())
+    Transform(CI);
+
 #ifndef NDEBUG
   // Verify the key has not changed with final arguments.
-  if (MD.ModuleCacheKey) {
+  if (MD.ModuleCacheKey && !MDC.Service.getCompilerInvocationTransformation()) {
     auto &CAS = MDC.ScanInstance.getOrCreateObjectStore();
     auto Key = createCompileJobCacheKey(CAS, Diags, CI);
     assert(Key);