Inherit dll attributes to static locals

This makes us handle static locals in exported/imported functions correctly.

Differential Revision: http://reviews.llvm.org/D4136

llvm-svn: 211173

clang/include/clang/Sema/SemaInternal.h

@@ -74,6 +74,18 @@ inline void MarkVarDeclODRUsed(VarDecl *Var,
 
   Var->markUsed(SemaRef.Context);
 }
+
+/// Return a DLL attribute from the declaration.
+inline InheritableAttr *getDLLAttr(Decl *D) {
+  assert(!(D->hasAttr<DLLImportAttr>() && D->hasAttr<DLLExportAttr>()) &&
+         "A declaration cannot be both dllimport and dllexport.");
+  if (auto *Import = D->getAttr<DLLImportAttr>())
+    return Import;
+  if (auto *Export = D->getAttr<DLLExportAttr>())
+    return Export;
+  return nullptr;
+}
+
 }
 
 #endif

clang/lib/CodeGen/CGDecl.cpp

@@ -201,6 +201,13 @@ CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
   if (D.getTLSKind())
     CGM.setTLSMode(GV, D);
 
+  if (D.isExternallyVisible()) {
+    if (D.hasAttr<DLLImportAttr>())
+      GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
+    else if (D.hasAttr<DLLExportAttr>())
+      GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass);
+  }
+
   // Make sure the result is of the correct type.
   unsigned ExpectedAddrSpace = CGM.getContext().getTargetAddressSpace(Ty);
   if (AddrSpace != ExpectedAddrSpace) {

clang/lib/CodeGen/MicrosoftCXXABI.cpp

@@ -1425,12 +1425,13 @@ void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
       Out.flush();
     }
 
-    // Create the guard variable with a zero-initializer.  Just absorb linkage
-    // and visibility from the guarded variable.
+    // Create the guard variable with a zero-initializer. Just absorb linkage,
+    // visibility and dll storage class from the guarded variable.
     GI->Guard =
         new llvm::GlobalVariable(CGM.getModule(), GuardTy, false,
                                  GV->getLinkage(), Zero, GuardName.str());
     GI->Guard->setVisibility(GV->getVisibility());
+    GI->Guard->setDLLStorageClass(GV->getDLLStorageClass());
   } else {
     assert(GI->Guard->getLinkage() == GV->getLinkage() &&
            "static local from the same function had different linkage");

clang/lib/Sema/SemaDecl.cpp

@@ -9097,6 +9097,18 @@ Sema::FinalizeDeclaration(Decl *ThisDecl) {
 
   checkAttributesAfterMerging(*this, *VD);
 
+  // Static locals inherit dll attributes from their function.
+  if (VD->isStaticLocal()) {
+    if (FunctionDecl *FD =
+            dyn_cast<FunctionDecl>(VD->getParentFunctionOrMethod())) {
+      if (Attr *A = getDLLAttr(FD)) {
+        auto *NewAttr = cast<InheritableAttr>(A->clone(getASTContext()));
+        NewAttr->setInherited(true);
+        VD->addAttr(NewAttr);
+      }
+    }
+  }
+
   // Imported static data members cannot be defined out-of-line.
   if (const DLLImportAttr *IA = VD->getAttr<DLLImportAttr>()) {
     if (VD->isStaticDataMember() && VD->isOutOfLine() &&

clang/lib/Sema/SemaDeclCXX.cpp

@@ -4347,17 +4347,6 @@ static void CheckAbstractClassUsage(AbstractUsageInfo &Info,
   }
 }
 
-/// \brief Return a DLL attribute from the declaration.
-static InheritableAttr *getDLLAttr(Decl *D) {
-  assert(!(D->hasAttr<DLLImportAttr>() && D->hasAttr<DLLExportAttr>()) &&
-         "A declaration cannot be both dllimport and dllexport.");
-  if (auto *Import = D->getAttr<DLLImportAttr>())
-    return Import;
-  if (auto *Export = D->getAttr<DLLExportAttr>())
-    return Export;
-  return nullptr;
-}
-
 /// \brief Check class-level dllimport/dllexport attribute.
 static void checkDLLAttribute(Sema &S, CXXRecordDecl *Class) {
   Attr *ClassAttr = getDLLAttr(Class);

clang/test/CodeGenCXX/dllexport.cpp

@@ -72,6 +72,22 @@ namespace ns { __declspec(dllexport) int ExternalGlobal; }
 // GNU-DAG: @ExternalAutoTypeGlobal                      = dllexport global %struct.External zeroinitializer, align 4
 __declspec(dllexport) auto ExternalAutoTypeGlobal = External();
 
+int f();
+// MSC-DAG: @"\01?x@?0??nonInlineStaticLocalsFunc@@YAHXZ@4HA" = internal {{(unnamed_addr )*}}global i32 0
+// MSC-DAG: @"\01?$S1@?0??nonInlineStaticLocalsFunc@@YAHXZ@4IA" = internal {{(unnamed_addr )*}}global i32 0
+int __declspec(dllexport) nonInlineStaticLocalsFunc() {
+  static int x = f();
+  return x++;
+};
+
+// MSC-DAG: @"\01?x@?1??inlineStaticLocalsFunc@@YAHXZ@4HA" = weak_odr dllexport global i32 0
+// MSC-DAG: @"\01??_B?1??inlineStaticLocalsFunc@@YAHXZ@51" = weak_odr dllexport global i32 0
+// Note: MinGW doesn't seem to export the static local here.
+inline int __declspec(dllexport) inlineStaticLocalsFunc() {
+  static int x = f();
+  return x++;
+}
+
 
 
 //===----------------------------------------------------------------------===//

clang/test/CodeGenCXX/dllimport.cpp

@@ -85,6 +85,15 @@ USEVAR(GlobalRedecl3)
 namespace ns { __declspec(dllimport) int ExternalGlobal; }
 USEVAR(ns::ExternalGlobal)
 
+int f();
+// MO1-DAG: @"\01?x@?1??inlineStaticLocalsFunc@@YAHXZ@4HA" = available_externally dllimport global i32 0
+// MO1-DAG: @"\01??_B?1??inlineStaticLocalsFunc@@YAHXZ@51" = available_externally dllimport global i32 0
+inline int __declspec(dllimport) inlineStaticLocalsFunc() {
+  static int x = f();
+  return x++;
+};
+USE(inlineStaticLocalsFunc);
+
 
 
 //===----------------------------------------------------------------------===//