Add support for threadsafe statics, and make them the default (matching gcc).

Daniel, I'd appreciate a review of the driver/cc1 parts.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@95508 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 85 insertions, 22 deletions

diff --git a/lib/CodeGen/CGDeclCXX.cpp b/lib/CodeGen/CGDeclCXX.cpp
index 3d5a4e8051..0de3b0be4b 100644
--- a/lib/CodeGen/CGDeclCXX.cpp
+++ b/lib/CodeGen/CGDeclCXX.cpp
@@ -184,42 +184,100 @@ void CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
   FinishFunction();
 }
 
+static llvm::Constant *getGuardAcquireFn(CodeGenFunction &CGF) {
+  // int __cxa_guard_acquire(__int64_t *guard_object);
+  
+  const llvm::Type *Int64PtrTy = 
+    llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
+  
+  std::vector<const llvm::Type*> Args(1, Int64PtrTy);
+  
+  const llvm::FunctionType *FTy =
+    llvm::FunctionType::get(CGF.ConvertType(CGF.getContext().IntTy),
+                            Args, /*isVarArg=*/false);
+  
+  return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_acquire");
+}
+
+static llvm::Constant *getGuardReleaseFn(CodeGenFunction &CGF) {
+  // void __cxa_guard_release(__int64_t *guard_object);
+  
+  const llvm::Type *Int64PtrTy = 
+    llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
+  
+  std::vector<const llvm::Type*> Args(1, Int64PtrTy);
+  
+  const llvm::FunctionType *FTy =
+  llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
+                          Args, /*isVarArg=*/false);
+  
+  return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release");
+}
+
+static llvm::Constant *getGuardAbortFn(CodeGenFunction &CGF) {
+  // void __cxa_guard_abort(__int64_t *guard_object);
+  
+  const llvm::Type *Int64PtrTy = 
+    llvm::Type::getInt64PtrTy(CGF.getLLVMContext());
+  
+  std::vector<const llvm::Type*> Args(1, Int64PtrTy);
+  
+  const llvm::FunctionType *FTy =
+  llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
+                          Args, /*isVarArg=*/false);
+  
+  return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort");
+}
+
 void
 CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D,
                                                llvm::GlobalVariable *GV) {
-  // FIXME: This should use __cxa_guard_{acquire,release}?
-
-  assert(!getContext().getLangOptions().ThreadsafeStatics &&
-         "thread safe statics are currently not supported!");
-
+  bool ThreadsafeStatics = getContext().getLangOptions().ThreadsafeStatics;
+  
   llvm::SmallString<256> GuardVName;
   CGM.getMangleContext().mangleGuardVariable(&D, GuardVName);
 
   // Create the guard variable.
-  llvm::GlobalValue *GuardV =
-    new llvm::GlobalVariable(CGM.getModule(), llvm::Type::getInt64Ty(VMContext),
+  const llvm::Type *Int64Ty = llvm::Type::getInt64Ty(VMContext);
+  llvm::GlobalValue *GuardVariable =
+    new llvm::GlobalVariable(CGM.getModule(), Int64Ty,
                              false, GV->getLinkage(),
-                llvm::Constant::getNullValue(llvm::Type::getInt64Ty(VMContext)),
+                             llvm::Constant::getNullValue(Int64Ty),
                              GuardVName.str());
 
   // Load the first byte of the guard variable.
   const llvm::Type *PtrTy
     = llvm::PointerType::get(llvm::Type::getInt8Ty(VMContext), 0);
-  llvm::Value *V = Builder.CreateLoad(Builder.CreateBitCast(GuardV, PtrTy),
-                                      "tmp");
+  llvm::Value *V = 
+    Builder.CreateLoad(Builder.CreateBitCast(GuardVariable, PtrTy), "tmp");
 
-  // Compare it against 0.
-  llvm::Value *nullValue
-    = llvm::Constant::getNullValue(llvm::Type::getInt8Ty(VMContext));
-  llvm::Value *ICmp = Builder.CreateICmpEQ(V, nullValue , "tobool");
-
-  llvm::BasicBlock *InitBlock = createBasicBlock("init");
+  llvm::BasicBlock *InitCheckBlock = createBasicBlock("init.check");
   llvm::BasicBlock *EndBlock = createBasicBlock("init.end");
 
-  // If the guard variable is 0, jump to the initializer code.
-  Builder.CreateCondBr(ICmp, InitBlock, EndBlock);
+  // Check if the first byte of the guard variable is zero.
+  Builder.CreateCondBr(Builder.CreateIsNull(V, "tobool"), 
+                       InitCheckBlock, EndBlock);
 
-  EmitBlock(InitBlock);
+  EmitBlock(InitCheckBlock);
+
+  if (ThreadsafeStatics) {
+    // Call __cxa_guard_acquire.
+    V = Builder.CreateCall(getGuardAcquireFn(*this), GuardVariable);
+               
+    llvm::BasicBlock *InitBlock = createBasicBlock("init");
+  
+    Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"),
+                         InitBlock, EndBlock);
+  
+    EmitBlock(InitBlock);
+
+    if (Exceptions) {
+      EHCleanupBlock Cleanup(*this);
+    
+      // Call __cxa_guard_abort.
+      Builder.CreateCall(getGuardAbortFn(*this), GuardVariable);
+    }
+  }
 
   if (D.getType()->isReferenceType()) {
     QualType T = D.getType();
@@ -232,9 +290,14 @@ CodeGenFunction::EmitStaticCXXBlockVarDeclInit(const VarDecl &D,
   } else
     EmitDeclInit(*this, D, GV);
 
-  Builder.CreateStore(llvm::ConstantInt::get(llvm::Type::getInt8Ty(VMContext),
-                                             1),
-                      Builder.CreateBitCast(GuardV, PtrTy));
+  if (ThreadsafeStatics) {
+    // Call __cxa_guard_release.
+    Builder.CreateCall(getGuardReleaseFn(*this), GuardVariable);
+  } else {
+    llvm::Value *One = 
+      llvm::ConstantInt::get(llvm::Type::getInt8Ty(VMContext), 1);
+    Builder.CreateStore(One, Builder.CreateBitCast(GuardVariable, PtrTy));
+  }
 
   EmitBlock(EndBlock);
 }