If a function definition has any sort of weak linkage, its static local

variables should have that linkage.  Otherwise, its static local
variables should have internal linkage.  To avoid computing this excessively,
set a function's linkage before we emit code for it.

Previously we were assigning weak linkage to the static variables of
static inline functions in C++, with predictably terrible results.  This
fixes that and also gives better linkage than 'weak' when merging is required.

llvm-svn: 104581

clang/lib/CodeGen/CGCXX.cpp

@@ -206,6 +206,7 @@ void CodeGenModule::EmitCXXConstructor(const CXXConstructorDecl *D,
     return;
 
   llvm::Function *Fn = cast<llvm::Function>(GetAddrOfCXXConstructor(D, Type));
+  setFunctionLinkage(D, Fn);
 
   CodeGenFunction(*this).GenerateCode(GlobalDecl(D, Type), Fn);
 
@@ -269,6 +270,7 @@ void CodeGenModule::EmitCXXDestructor(const CXXDestructorDecl *D,
     return;
 
   llvm::Function *Fn = cast<llvm::Function>(GetAddrOfCXXDestructor(D, Type));
+  setFunctionLinkage(D, Fn);
 
   CodeGenFunction(*this).GenerateCode(GlobalDecl(D, Type), Fn);
 

clang/lib/CodeGen/CGDecl.cpp

@@ -114,14 +114,14 @@ void CodeGenFunction::EmitBlockVarDecl(const VarDecl &D) {
     llvm::GlobalValue::LinkageTypes Linkage = 
       llvm::GlobalValue::InternalLinkage;
 
-    // If this is a static declaration inside an inline function, it must have
-    // weak linkage so that the linker will merge multiple definitions of it.
-    if (getContext().getLangOptions().CPlusPlus) {
-      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CurFuncDecl)) {
-        if (FD->isInlined())
-          Linkage = llvm::GlobalValue::WeakAnyLinkage;
-      }
-    }
+    // If the function definition has some sort of weak linkage, its
+    // static variables should also be weak so that they get properly
+    // uniqued.  We can't do this in C, though, because there's no
+    // standard way to agree on which variables are the same (i.e.
+    // there's no mangling).
+    if (getContext().getLangOptions().CPlusPlus)
+      if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
+        Linkage = CurFn->getLinkage();
     
     return EmitStaticBlockVarDecl(D, Linkage);
   }

clang/lib/CodeGen/CGVTables.cpp

@@ -2723,7 +2723,7 @@ void CodeGenFunction::GenerateThunk(llvm::Function *Fn, GlobalDecl GD,
   CXXThisDecl->Destroy(getContext());
   
   // Set the right linkage.
-  Fn->setLinkage(CGM.getFunctionLinkage(MD));
+  CGM.setFunctionLinkage(MD, Fn);
   
   // Set the right visibility.
   CGM.setGlobalVisibility(Fn, MD);

clang/lib/CodeGen/CodeGenModule.cpp

@@ -361,7 +361,6 @@ CodeGenModule::getFunctionLinkage(const FunctionDecl *D) {
 /// variables (these details are set in EmitGlobalVarDefinition for variables).
 void CodeGenModule::SetFunctionDefinitionAttributes(const FunctionDecl *D,
                                                     llvm::GlobalValue *GV) {
-  GV->setLinkage(getFunctionLinkage(D));
   SetCommonAttributes(D, GV);
 }
 
@@ -1330,6 +1329,7 @@ void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD) {
   }
 
   llvm::Function *Fn = cast<llvm::Function>(Entry);
+  setFunctionLinkage(D, Fn);
 
   CodeGenFunction(*this).GenerateCode(D, Fn);
 

clang/lib/CodeGen/CodeGenModule.h

@@ -436,6 +436,10 @@ public:
   llvm::GlobalVariable::LinkageTypes
   getFunctionLinkage(const FunctionDecl *FD);
 
+  void setFunctionLinkage(const FunctionDecl *FD, llvm::GlobalValue *V) {
+    V->setLinkage(getFunctionLinkage(FD));
+  }
+
   /// getVTableLinkage - Return the appropriate linkage for the vtable, VTT,
   /// and type information of the given class.
   static llvm::GlobalVariable::LinkageTypes 

clang/test/CodeGenCXX/static-init.cpp

@@ -2,8 +2,9 @@
 
 // CHECK: @_ZZ1hvE1i = internal global i32 0, align 4
 
-// CHECK: @_ZZ2h2vE1i = weak global i32 0
-// CHECK: @_ZGVZ2h2vE1i = weak global i64 0
+// CHECK: @_ZZN5test16getvarEiE3var = internal constant [4 x i32] [i32 1, i32 0, i32 2, i32 4], align 4
+// CHECK: @_ZZ2h2vE1i = linkonce_odr global i32 0
+// CHECK: @_ZGVZ2h2vE1i = linkonce_odr global i64 0
 
 struct A {
   A();
@@ -47,3 +48,13 @@ namespace test0 {
     static A r;
   }
 }
+
+namespace test1 {
+  // CHECK: define internal i32 @_ZN5test16getvarEi(
+  static inline int getvar(int index) {
+    static const int var[] = { 1, 0, 2, 4 };
+    return var[index];
+  }
+
+  void test() { (void) getvar(2); }
+}