[codegen] When emitting functions with the "cf_no_release" attribute, attach the "clang-arc-no_release" string ttribute to the function.

[gottesmm]

Summary

This will be recognized by the arc optimizer and is intended to be used with
functions like malloc. This will enable us to not hard wire this in the objc arc
optimizer.

[gottesmm]

I failed at using fabricator. I am going to close this until I get in the attribute version. That is what I meant to give to Doug to review.

lib/CodeGen/CodeGenModule.cpp

void CodeGenModule::SetLLVMFunctionAttributes(const Decl *D,
                                               const CGFunctionInfo &Info,
                                               llvm::Function *F) {
   unsigned CallingConv;
   AttributeListType AttributeList;
   ConstructAttributeList(F->getName(), Info, D, AttributeList, CallingConv,
                          false);
   F->setAttributes(llvm::AttributeSet::get(getLLVMContext(), AttributeList));
   F->setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
+
+  // If the optimization level is greater than 0 and we are compiling with ARC,
+  // we attach clang-arc-nodecrement string attribute to any decl with
+  // CFNoReleaseAttr attached.
+  if (CodeGenOpts.OptimizationLevel > 0 &&
+      LangOpts.ObjCAutoRefCount&& D->hasAttr<CFNoReleaseAttr>()) {
+    F->addFnAttr("clang-arc-norelease");
+  }
 }
 
 /// Determines whether the language options require us to model
 /// unwind exceptions.  We treat -fexceptions as mandating this
 /// except under the fragile ObjC ABI with only ObjC exceptions
 /// enabled.  This means, for example, that C with -fexceptions
 /// enables this.
 static bool hasUnwindExceptions(const LangOptions &LangOpts) {

test/CodeGenObjC/arc-cf-no-release.m

+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -O2 -disable-llvm-optzns -o - %s | FileCheck %s
+
+// CHECK: define void @norelease_defn() #[[NORELEASE_DEFN_ATTR:[0-9]+]] {
+// CHECK: define void @mayrelease_defn() #[[MAYRELEASE_DEFN_ATTR:[0-9]+]] {
+// CHECK: declare void @norelease_decl(...) #[[NORELEASE_DECL_ATTR:[0-9]+]]
+// CHECK: declare void @mayrelease_decl(...) #[[MAYRELEASE_DECL_ATTR:[0-9]+]]
+
+// CHECK: attributes #[[NORELEASE_DEFN_ATTR]] = { {{.*}}"clang-arc-norelease"{{.*}} }
+// CHECK-NOT: attributes #[[MAYRELEASE_DEFN_ATTR]] = { {{.*}}"clang-arc-norelease"{{.*}} }
+// CHECK: attributes #[[NORELEASE_DECL_ATTR]] = { {{.*}}"clang-arc-norelease"{{.*}}}
+// CHECK-NOT: attributes [[MAYRELEASE_DEFN_ATTR]] = { {{.*}}"clang-arc-norelease"{{.*}} }
+
+void norelease_decl() __attribute__((cf_no_release));
+void mayrelease_decl();
+
+void norelease_defn() __attribute__((cf_no_release)) {}
+void mayrelease_defn() {}
+
+void call() {
+  norelease_decl();
+  mayrelease_decl();
+  norelease_defn();
+  mayrelease_defn();
+}