From: Hans Wennborg <hans@hanshq.net>
Date: Wed, 15 Feb 2017 23:28:10 +0000 (+0000)
Subject: [dllimport] Check for dtor references in functions
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=14434fb9b76150b53d7e585a22fe258542e1b6f3;p=clang

[dllimport] Check for dtor references in functions

Destructor references are not modelled explicitly in the AST. This adds
checks for destructor calls due to variable definitions and temporaries.

If a dllimport function references a non-dllimport destructor, it must
not be emitted available_externally, as the referenced destructor might
live across the DLL boundary and isn't exported.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@295258 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 4353e3a922..62613d82ab 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -1693,6 +1693,16 @@ void CodeGenModule::EmitGlobal(GlobalDecl GD) {
   }
 }
 
+// Check if T is a class type with a destructor that's not dllimport.
+static bool HasNonDllImportDtor(QualType T) {
+  if (const auto *RT = T->getBaseElementTypeUnsafe()->getAs<RecordType>())
+    if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl()))
+      if (RD->getDestructor() && !RD->getDestructor()->hasAttr<DLLImportAttr>())
+        return true;
+
+  return false;
+}
+
 namespace {
   struct FunctionIsDirectlyRecursive :
     public RecursiveASTVisitor<FunctionIsDirectlyRecursive> {
@@ -1726,6 +1736,7 @@ namespace {
     }
   };
 
+  // Make sure we're not referencing non-imported vars or functions.
   struct DLLImportFunctionVisitor
       : public RecursiveASTVisitor<DLLImportFunctionVisitor> {
     bool SafeToInline = true;
@@ -1733,12 +1744,25 @@ namespace {
     bool shouldVisitImplicitCode() const { return true; }
 
     bool VisitVarDecl(VarDecl *VD) {
-      // A thread-local variable cannot be imported.
-      SafeToInline = !VD->getTLSKind();
+      if (VD->getTLSKind()) {
+        // A thread-local variable cannot be imported.
+        SafeToInline = false;
+        return SafeToInline;
+      }
+
+      // A variable definition might imply a destructor call.
+      if (VD->isThisDeclarationADefinition())
+        SafeToInline = !HasNonDllImportDtor(VD->getType());
+
+      return SafeToInline;
+    }
+
+    bool VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
+      if (const auto *D = E->getTemporary()->getDestructor())
+        SafeToInline = D->hasAttr<DLLImportAttr>();
       return SafeToInline;
     }
 
-    // Make sure we're not referencing non-imported vars or functions.
     bool VisitDeclRefExpr(DeclRefExpr *E) {
       ValueDecl *VD = E->getDecl();
       if (isa<FunctionDecl>(VD))
@@ -1747,10 +1771,12 @@ namespace {
         SafeToInline = !V->hasGlobalStorage() || V->hasAttr<DLLImportAttr>();
       return SafeToInline;
     }
+
     bool VisitCXXConstructExpr(CXXConstructExpr *E) {
       SafeToInline = E->getConstructor()->hasAttr<DLLImportAttr>();
       return SafeToInline;
     }
+
     bool VisitCXXMemberCallExpr(CXXMemberCallExpr *E) {
       CXXMethodDecl *M = E->getMethodDecl();
       if (!M) {
@@ -1761,10 +1787,12 @@ namespace {
       }
       return SafeToInline;
     }
+
     bool VisitCXXDeleteExpr(CXXDeleteExpr *E) {
       SafeToInline = E->getOperatorDelete()->hasAttr<DLLImportAttr>();
       return SafeToInline;
     }
+
     bool VisitCXXNewExpr(CXXNewExpr *E) {
       SafeToInline = E->getOperatorNew()->hasAttr<DLLImportAttr>();
       return SafeToInline;
@@ -1793,16 +1821,6 @@ CodeGenModule::isTriviallyRecursive(const FunctionDecl *FD) {
   return Walker.Result;
 }
 
-// Check if T is a class type with a destructor that's not dllimport.
-static bool HasNonDllImportDtor(QualType T) {
-  if (const auto *RT = T->getBaseElementTypeUnsafe()->getAs<RecordType>())
-    if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl()))
-      if (RD->getDestructor() && !RD->getDestructor()->hasAttr<DLLImportAttr>())
-        return true;
-
-  return false;
-}
-
 bool CodeGenModule::shouldEmitFunction(GlobalDecl GD) {
   if (getFunctionLinkage(GD) != llvm::Function::AvailableExternallyLinkage)
     return true;
diff --git a/test/CodeGenCXX/dllimport.cpp b/test/CodeGenCXX/dllimport.cpp
index 731239e5ed..372a96ba2e 100644
--- a/test/CodeGenCXX/dllimport.cpp
+++ b/test/CodeGenCXX/dllimport.cpp
@@ -368,6 +368,13 @@ struct ClassWithCtor { ClassWithCtor() {} };
 struct __declspec(dllimport) ClassWithNonDllImportFieldWithCtor { ClassWithCtor t; };
 USECLASS(ClassWithNonDllImportFieldWithCtor);
 // MO1-DAG: declare dllimport x86_thiscallcc %struct.ClassWithNonDllImportFieldWithCtor* @"\01??0ClassWithNonDllImportFieldWithCtor@@QAE@XZ"(%struct.ClassWithNonDllImportFieldWithCtor* returned)
+struct ClassWithImplicitDtor { __declspec(dllimport) ClassWithImplicitDtor(); ClassWithDtor member; };
+__declspec(dllimport) inline void ReferencingDtorThroughDefinition() { ClassWithImplicitDtor x; };
+USE(ReferencingDtorThroughDefinition)
+// MO1-DAG: declare dllimport void @"\01?ReferencingDtorThroughDefinition@@YAXXZ"()
+__declspec(dllimport) inline void ReferencingDtorThroughTemporary() { ClassWithImplicitDtor(); };
+USE(ReferencingDtorThroughTemporary)
+// MO1-DAG: declare dllimport void @"\01?ReferencingDtorThroughTemporary@@YAXXZ"()
 
 // A dllimport function with a TLS variable must not be available_externally.
 __declspec(dllimport) inline void FunctionWithTLSVar() { static __thread int x = 42; }