Add C bindings for manipulating function return value attributes

[pcc]

Add Go bindings

bindings/go/llvm/ir.go

 func (v Value) AddTargetDependentFunctionAttr(attr, value string) {
   cattr := C.CString(attr)
   defer C.free(unsafe.Pointer(cattr))
   cvalue := C.CString(value)
   defer C.free(unsafe.Pointer(cvalue))
   C.LLVMAddTargetDependentFunctionAttr(v.C, cattr, cvalue)
 }
 
+func (v Value) AddFunctionReturnAttr(a Attribute) {
+  if a >= 1<<32 {
+    panic("attribute value currently unsupported")
+  }
+  C.LLVMAddFunctionReturnAttr(v.C, C.LLVMAttribute(a))
+}
+func (v Value) RemoveFunctionReturnAttr(a Attribute) {
+  if a >= 1<<32 {
+    panic("attribute value currently unsupported")
+  }
+  C.LLVMRemoveFunctionReturnAttr(v.C, C.LLVMAttribute(a))
+}
+func (v Value) FunctionReturnAttr() Attribute { return Attribute(C.LLVMGetFunctionReturnAttr(v.C)) }
+
 // Operations on parameters
 func (v Value) ParamsCount() int { return int(C.LLVMCountParams(v.C)) }
 func (v Value) Params() []Value {
   out := make([]Value, v.ParamsCount())
   if len(out) > 0 {
     C.LLVMGetParams(v.C, llvmValueRefPtr(&out[0]))
   }
   return out

include/llvm-c/Core.h

 LLVMAttribute LLVMGetFunctionAttr(LLVMValueRef Fn);
 
 /**
  * Remove an attribute from a function.
  */
 void LLVMRemoveFunctionAttr(LLVMValueRef Fn, LLVMAttribute PA);
 
 /**
+ * Add an attribute to the return value of a function.
+ *
+ * @see llvm::Function::addAttribute()
+ */
+void LLVMAddFunctionReturnAttr(LLVMValueRef Fn, LLVMAttribute PA);
+
+/**
+ * Obtain an attribute from the return value of a function.
+ *
+ * @see llvm::Function::getAttributes()
+ */
+LLVMAttribute LLVMGetFunctionReturnAttr(LLVMValueRef Fn);
+
+/**
+ * Remove an attribute from the return value of a function.
+ */
+void LLVMRemoveFunctionReturnAttr(LLVMValueRef Fn, LLVMAttribute PA);
+
+/**
  * @defgroup LLVMCCoreValueFunctionParameters Function Parameters
  *
  * Functions in this group relate to arguments/parameters on functions.
  *
  * Functions in this group expect LLVMValueRef instances that correspond
  * to llvm::Function instances.
  *
  * @{

lib/IR/Core.cpp

 }
 
 LLVMAttribute LLVMGetFunctionAttr(LLVMValueRef Fn) {
   Function *Func = unwrap<Function>(Fn);
   const AttributeSet PAL = Func->getAttributes();
   return (LLVMAttribute)PAL.Raw(AttributeSet::FunctionIndex);
 }
 
+void LLVMAddFunctionReturnAttr(LLVMValueRef Fn, LLVMAttribute PA) {
+  Function *Func = unwrap<Function>(Fn);
+  const AttributeSet PAL = Func->getAttributes();
+  AttrBuilder B(PA);
+  const AttributeSet PALnew =
+    PAL.addAttributes(Func->getContext(), AttributeSet::ReturnIndex,
+                      AttributeSet::get(Func->getContext(),
+                                        AttributeSet::ReturnIndex, B));
+  Func->setAttributes(PALnew);
+}
+
+void LLVMRemoveFunctionReturnAttr(LLVMValueRef Fn, LLVMAttribute PA) {
+  Function *Func = unwrap<Function>(Fn);
+  const AttributeSet PAL = Func->getAttributes();
+  AttrBuilder B(PA);
+  const AttributeSet PALnew =
+    PAL.removeAttributes(Func->getContext(), AttributeSet::ReturnIndex,
+                         AttributeSet::get(Func->getContext(),
+                                           AttributeSet::ReturnIndex, B));
+  Func->setAttributes(PALnew);
+}
+
+LLVMAttribute LLVMGetFunctionReturnAttr(LLVMValueRef Fn) {
+  Function *Func = unwrap<Function>(Fn);
+  const AttributeSet PAL = Func->getAttributes();
+  return (LLVMAttribute)PAL.Raw(AttributeSet::ReturnIndex);
+}
+
 /*--.. Operations on parameters ............................................--*/
 
 unsigned LLVMCountParams(LLVMValueRef FnRef) {
   // This function is strictly redundant to
   //   LLVMCountParamTypes(LLVMGetElementType(LLVMTypeOf(FnRef)))
   return unwrap<Function>(FnRef)->arg_size();
 }