Avoid double deletion in Clang driver.

Llvm module object is shared between CodeGenerator and BackendConsumer,
in both classes it is stored as std::unique_ptr, which is not a good
design solution and can cause double deletion error. Usually it does
not occur because in BackendConsumer::HandleTranslationUnit the
ownership of CodeGenerator over the module is taken away. If however
this method is not called, the module is deleted twice and compiler crashes.

As the module owned by BackendConsumer is always the same as CodeGenerator
has, pointer to llvm module can be removed from BackendGenerator.

Differential Revision: http://reviews.llvm.org/D15450

llvm-svn: 261222

clang/lib/CodeGen/CodeGenAction.cpp

@@ -53,7 +53,6 @@ namespace clang {
 
     std::unique_ptr<CodeGenerator> Gen;
 
-    std::unique_ptr<llvm::Module> TheModule;
     SmallVector<std::pair<unsigned, std::unique_ptr<llvm::Module>>, 4>
         LinkModules;
 
@@ -81,7 +80,10 @@ namespace clang {
         this->LinkModules.push_back(
             std::make_pair(I.first, std::unique_ptr<llvm::Module>(I.second)));
     }
-    std::unique_ptr<llvm::Module> takeModule() { return std::move(TheModule); }
+    llvm::Module *getModule() const { return Gen->GetModule(); }
+    std::unique_ptr<llvm::Module> takeModule() {
+      return std::unique_ptr<llvm::Module>(Gen->ReleaseModule());
+    }
     void releaseLinkModules() {
       for (auto &I : LinkModules)
         I.second.release();
@@ -101,8 +103,6 @@ namespace clang {
 
       Gen->Initialize(Ctx);
 
-      TheModule.reset(Gen->GetModule());
-
       if (llvm::TimePassesIsEnabled)
         LLVMIRGeneration.stopTimer();
     }
@@ -149,25 +149,12 @@ namespace clang {
       }
 
       // Silently ignore if we weren't initialized for some reason.
-      if (!TheModule)
-        return;
-
-      // Make sure IR generation is happy with the module. This is released by
-      // the module provider.
-      llvm::Module *M = Gen->ReleaseModule();
-      if (!M) {
-        // The module has been released by IR gen on failures, do not double
-        // free.
-        TheModule.release();
+      if (!getModule())
         return;
-      }
-
-      assert(TheModule.get() == M &&
-             "Unexpected module change during IR generation");
 
       // Install an inline asm handler so that diagnostics get printed through
       // our diagnostics hooks.
-      LLVMContext &Ctx = TheModule->getContext();
+      LLVMContext &Ctx = getModule()->getContext();
       LLVMContext::InlineAsmDiagHandlerTy OldHandler =
         Ctx.getInlineAsmDiagnosticHandler();
       void *OldContext = Ctx.getInlineAsmDiagnosticContext();
@@ -182,13 +169,13 @@ namespace clang {
       for (auto &I : LinkModules) {
         unsigned LinkFlags = I.first;
         CurLinkModule = I.second.get();
-        if (Linker::linkModules(*M, std::move(I.second), LinkFlags))
+        if (Linker::linkModules(*getModule(), std::move(I.second), LinkFlags))
           return;
       }
 
       EmitBackendOutput(Diags, CodeGenOpts, TargetOpts, LangOpts,
                         C.getTargetInfo().getDataLayoutString(),
-                        TheModule.get(), Action, AsmOutStream);
+                        getModule(), Action, AsmOutStream);
 
       Ctx.setInlineAsmDiagnosticHandler(OldHandler, OldContext);
 

clang/unittests/Frontend/CMakeLists.txt

@@ -4,11 +4,13 @@ set(LLVM_LINK_COMPONENTS
 
 add_clang_unittest(FrontendTests
   FrontendActionTest.cpp
+  CodeGenActionTest.cpp
   )
 target_link_libraries(FrontendTests
   clangAST
   clangBasic
   clangFrontend
   clangLex
   clangSema
+  clangCodeGen
   )