From 41c1f79dfe20261a0e427ac50dbead55d4ebd118 Mon Sep 17 00:00:00 2001
From: Serge Pavlov <sepavloff@gmail.com>
Date: Thu, 18 Feb 2016 16:42:09 +0000
Subject: 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 | 29 ++++++++---------------------
 1 file changed, 8 insertions(+), 21 deletions(-)

(limited to 'clang/lib/CodeGen/CodeGenAction.cpp')

diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 645663ff7b7..3d333c88f99 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/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);
 
-- 
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