// interfaceMethod returns a function and receiver pointer for the specified
// interface and method pair.
func (fr *frame) interfaceMethod(lliface llvm.Value, ifacety types.Type, method *types.Func) (fn, recv *govalue) {
llitab := fr.builder.CreateExtractValue(lliface, 0, "")
recv = newValue(fr.builder.CreateExtractValue(lliface, 1, ""), types.Typ[types.UnsafePointer])
methodset := fr.types.MethodSet(ifacety)
// TODO(axw) cache ordered method index
index := -1
for i, m := range orderedMethodSet(methodset) {
if m.Obj() == method {
index = i
break
}
}
if index == -1 {
panic("could not find method index")
}
llitab = fr.builder.CreateBitCast(llitab, llvm.PointerType(llvm.PointerType(llvm.Int8Type(), 0), 0), "")
// Skip runtime type pointer.
llifnptr := fr.builder.CreateGEP(llitab, []llvm.Value{
llvm.ConstInt(llvm.Int32Type(), uint64(index+1), false),
}, "")
llifn := fr.builder.CreateLoad(llifnptr, "")
// Replace receiver type with unsafe.Pointer.
recvparam := types.NewParam(0, nil, "", types.Typ[types.UnsafePointer])
sig := method.Type().(*types.Signature)
sig = types.NewSignature(nil, recvparam, sig.Params(), sig.Results(), sig.Variadic())
fn = newValue(llifn, sig)
return
}
func checkFuncValue(t *testing.T, prog *ssa.Program, obj *types.Func) {
fn := prog.FuncValue(obj)
// fmt.Printf("FuncValue(%s) = %s\n", obj, fn) // debugging
if fn == nil {
if obj.Name() != "interfaceMethod" {
t.Errorf("FuncValue(%s) == nil", obj)
}
return
}
if fnobj := fn.Object(); fnobj != obj {
t.Errorf("FuncValue(%s).Object() == %s; value was %s",
obj, fnobj, fn.Name())
return
}
if !types.Identical(fn.Type(), obj.Type()) {
t.Errorf("FuncValue(%s).Type() == %s", obj, fn.Type())
return
}
}
// makeBound returns a bound method wrapper (or "bound"), a synthetic
// function that delegates to a concrete or interface method denoted
// by obj. The resulting function has no receiver, but has one free
// variable which will be used as the method's receiver in the
// tail-call.
//
// Use MakeClosure with such a wrapper to construct a bound method
// closure. e.g.:
//
// type T int or: type T interface { meth() }
// func (t T) meth()
// var t T
// f := t.meth
// f() // calls t.meth()
//
// f is a closure of a synthetic wrapper defined as if by:
//
// f := func() { return t.meth() }
//
// Unlike makeWrapper, makeBound need perform no indirection or field
// selections because that can be done before the closure is
// constructed.
//
// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
//
func makeBound(prog *Program, obj *types.Func) *Function {
prog.methodsMu.Lock()
defer prog.methodsMu.Unlock()
fn, ok := prog.bounds[obj]
if !ok {
description := fmt.Sprintf("bound method wrapper for %s", obj)
if prog.mode&LogSource != 0 {
defer logStack("%s", description)()
}
fn = &Function{
name: obj.Name() + "$bound",
object: obj,
Signature: changeRecv(obj.Type().(*types.Signature), nil), // drop receiver
Synthetic: description,
Prog: prog,
pos: obj.Pos(),
}
fv := &FreeVar{name: "recv", typ: recvType(obj), parent: fn}
fn.FreeVars = []*FreeVar{fv}
fn.startBody()
createParams(fn, 0)
var c Call
if !isInterface(recvType(obj)) { // concrete
c.Call.Value = prog.declaredFunc(obj)
c.Call.Args = []Value{fv}
} else {
c.Call.Value = fv
c.Call.Method = obj
}
for _, arg := range fn.Params {
c.Call.Args = append(c.Call.Args, arg)
}
emitTailCall(fn, &c)
fn.finishBody()
prog.bounds[obj] = fn
}
return fn
}
// recvType returns the receiver type of method obj.
func recvType(obj *types.Func) types.Type {
return obj.Type().(*types.Signature).Recv().Type()
}