Bug 8765: Honor assembler labels for builtins. Ensure that the label is

mangled to avoid doing it twice for platforms that use prefixes like
Darwin.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@131311 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CodeGenModule.cpp

@@ -1574,14 +1574,24 @@ llvm::Value *CodeGenModule::getBuiltinLibFunction(const FunctionDecl *FD,
          "isn't a lib fn");
 
   // Get the name, skip over the __builtin_ prefix (if necessary).
-  const char *Name = Context.BuiltinInfo.GetName(BuiltinID);
-  if (Context.BuiltinInfo.isLibFunction(BuiltinID))
-    Name += 10;
+  llvm::StringRef Name;
+  GlobalDecl D(FD);
+
+  // If the builtin has been declared explicitly with an assembler label,
+  // use the mangled name. This differs from the plain label on platforms
+  // that prefix labels.
+  if (const AsmLabelAttr *ALA = FD->getAttr<AsmLabelAttr>())
+    Name = getMangledName(D);
+  else if (Context.BuiltinInfo.isLibFunction(BuiltinID))
+    Name = Context.BuiltinInfo.GetName(BuiltinID) + 10;
+  else
+    Name = Context.BuiltinInfo.GetName(BuiltinID);
+
 
   const llvm::FunctionType *Ty =
     cast<llvm::FunctionType>(getTypes().ConvertType(FD->getType()));
 
-  return GetOrCreateLLVMFunction(Name, Ty, GlobalDecl(FD), /*ForVTable=*/false);
+  return GetOrCreateLLVMFunction(Name, Ty, D, /*ForVTable=*/false);
 }
 
 llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,const llvm::Type **Tys,

test/CodeGen/asm-label.c

@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple=i686-pc-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefix=LINUX
+// RUN: %clang_cc1 -triple=i686-apple-darwin9 -emit-llvm %s -o - | FileCheck %s --check-prefix=DARWIN
+
+char *strerror(int) asm("alias");
+
+void test(void)
+{
+	strerror(-1);
+}
+
+// LINUX: declare i8* @alias(i32)
+// DARWIN: declare i8* @"\01alias"(i32)