func NewTypeMap(llvmtm *LLVMTypeMap, module llvm.Module, pkgpath string, exprTypes map[ast.Expr]types.Type, c *FunctionCache, r Resolver) *TypeMap {
	tm := &TypeMap{
		LLVMTypeMap: llvmtm,
		module:      module,
		pkgpath:     pkgpath,
		types:       make(map[string]runtimeTypeInfo),
		expr:        exprTypes,
		functions:   c,
		resolver:    r,
	}

	// Load runtime/reflect types, and generate LLVM types for
	// the structures we need to populate runtime type information.
	pkg, err := c.compiler.parseReflect()
	if err != nil {
		panic(err) // FIXME return err
	}
	reflectLLVMType := func(name string) llvm.Type {
		obj := pkg.Scope.Lookup(name)
		if obj == nil {
			panic(fmt.Errorf("Failed to find type: %s", name))
		}
		return tm.ToLLVM(obj.Type.(types.Type))
	}
	tm.runtimeType = reflectLLVMType("runtimeType")
	tm.runtimeCommonType = reflectLLVMType("commonType")
	tm.runtimeUncommonType = reflectLLVMType("uncommonType")
	tm.runtimeArrayType = reflectLLVMType("arrayType")
	tm.runtimeChanType = reflectLLVMType("chanType")
	tm.runtimeFuncType = reflectLLVMType("funcType")
	tm.runtimeMethod = reflectLLVMType("method")
	tm.runtimeImethod = reflectLLVMType("imethod")
	tm.runtimeInterfaceType = reflectLLVMType("interfaceType")
	tm.runtimeMapType = reflectLLVMType("mapType")
	tm.runtimePtrType = reflectLLVMType("ptrType")
	tm.runtimeSliceType = reflectLLVMType("sliceType")
	tm.runtimeStructType = reflectLLVMType("structType")
	tm.commonType = pkg.Scope.Lookup("commonType").Type.(*types.Name)

	// Types for algorithms. See 'runtime/runtime.h'.
	uintptrType := tm.target.IntPtrType()
	voidPtrType := llvm.PointerType(llvm.Int8Type(), 0)
	boolType := llvm.Int1Type()

	// Create runtime algorithm function types.
	params := []llvm.Type{uintptrType, voidPtrType}
	tm.hashAlgFunctionType = llvm.FunctionType(uintptrType, params, false)
	params = []llvm.Type{uintptrType, uintptrType, uintptrType}
	tm.equalAlgFunctionType = llvm.FunctionType(boolType, params, false)
	params = []llvm.Type{uintptrType, voidPtrType}
	tm.printAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)
	params = []llvm.Type{uintptrType, voidPtrType, voidPtrType}
	tm.copyAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)

	return tm
}

func NewTypeMap(llvmtm *LLVMTypeMap, pkgpath string, exprTypes map[ast.Expr]types.Type, c *FunctionCache, p map[*ast.Object]string, r Resolver) *TypeMap {
	tm := &TypeMap{
		LLVMTypeMap: llvmtm,
		pkgpath:     pkgpath,
		types:       make(map[types.Type]llvm.Value),
		expr:        exprTypes,
		pkgmap:      p,
		functions:   c,
		resolver:    r,
	}

	// Load "reflect.go", and generate LLVM types for the runtime type
	// structures.
	pkg, err := parseReflect()
	if err != nil {
		panic(err) // FIXME return err
	}
	objToLLVMType := func(name string) llvm.Type {
		obj := pkg.Scope.Lookup(name)
		return tm.ToLLVM(obj.Type.(types.Type))
	}
	tm.runtimeType = objToLLVMType("runtimeType")
	tm.runtimeCommonType = objToLLVMType("commonType")
	tm.runtimeUncommonType = objToLLVMType("uncommonType")
	tm.runtimeArrayType = objToLLVMType("arrayType")
	tm.runtimeChanType = objToLLVMType("chanType")
	tm.runtimeFuncType = objToLLVMType("funcType")
	tm.runtimeMethod = objToLLVMType("method")
	tm.runtimeImethod = objToLLVMType("imethod")
	tm.runtimeInterfaceType = objToLLVMType("interfaceType")
	tm.runtimeMapType = objToLLVMType("mapType")
	tm.runtimePtrType = objToLLVMType("ptrType")
	tm.runtimeSliceType = objToLLVMType("sliceType")
	tm.runtimeStructType = objToLLVMType("structType")

	// Types for algorithms. See 'runtime/runtime.h'.
	uintptrType := tm.target.IntPtrType()
	voidPtrType := llvm.PointerType(llvm.Int8Type(), 0)
	boolType := llvm.Int1Type()

	// Create runtime algorithm function types.
	params := []llvm.Type{uintptrType, voidPtrType}
	tm.hashAlgFunctionType = llvm.FunctionType(uintptrType, params, false)
	params = []llvm.Type{uintptrType, uintptrType, uintptrType}
	tm.equalAlgFunctionType = llvm.FunctionType(boolType, params, false)
	params = []llvm.Type{uintptrType, voidPtrType}
	tm.printAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)
	params = []llvm.Type{uintptrType, voidPtrType, voidPtrType}
	tm.copyAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)

	return tm
}

func getnewgoroutine(module llvm.Module) llvm.Value {
	fn := module.NamedFunction("llgo_newgoroutine")
	if fn.IsNil() {
		i8Ptr := llvm.PointerType(llvm.Int8Type(), 0)
		VoidFnPtr := llvm.PointerType(llvm.FunctionType(
			llvm.VoidType(), []llvm.Type{i8Ptr}, false), 0)
		i32 := llvm.Int32Type()
		fn_type := llvm.FunctionType(
			llvm.VoidType(), []llvm.Type{VoidFnPtr, i8Ptr, i32}, true)
		fn = llvm.AddFunction(module, "llgo_newgoroutine", fn_type)
		fn.SetFunctionCallConv(llvm.CCallConv)
	}
	return fn
}

func addExterns(m *llgo.Module) {
	CharPtr := llvm.PointerType(llvm.Int8Type(), 0)
	fn_type := llvm.FunctionType(
		llvm.Int32Type(), []llvm.Type{CharPtr}, false)
	fflush := llvm.AddFunction(m.Module, "fflush", fn_type)
	fflush.SetFunctionCallConv(llvm.CCallConv)
}

// mapInsert inserts a key into a map, returning a pointer to the memory
// location for the value.
func (c *compiler) mapInsert(m *LLVMValue, key Value) *LLVMValue {
	mapType := m.Type().(*types.Map)
	mapinsert := c.module.Module.NamedFunction("runtime.mapinsert")
	ptrType := c.target.IntPtrType()
	if mapinsert.IsNil() {
		// params: dynamic type, mapptr, keyptr
		paramTypes := []llvm.Type{ptrType, ptrType, ptrType}
		funcType := llvm.FunctionType(ptrType, paramTypes, false)
		mapinsert = llvm.AddFunction(c.module.Module, "runtime.mapinsert", funcType)
	}
	args := make([]llvm.Value, 3)
	args[0] = llvm.ConstPtrToInt(c.types.ToRuntime(m.Type()), ptrType)
	args[1] = c.builder.CreatePtrToInt(m.pointer.LLVMValue(), ptrType, "")

	if lv, islv := key.(*LLVMValue); islv && lv.pointer != nil {
		args[2] = c.builder.CreatePtrToInt(lv.pointer.LLVMValue(), ptrType, "")
	}
	if args[2].IsNil() {
		// Create global constant, so we can take its address.
		global := llvm.AddGlobal(c.module.Module, c.types.ToLLVM(key.Type()), "")
		global.SetGlobalConstant(true)
		global.SetInitializer(key.LLVMValue())
		args[2] = c.builder.CreatePtrToInt(global, ptrType, "")
	}

	eltPtrType := &types.Pointer{Base: mapType.Elt}
	result := c.builder.CreateCall(mapinsert, args, "")
	result = c.builder.CreateIntToPtr(result, c.types.ToLLVM(eltPtrType), "")
	value := c.NewLLVMValue(result, eltPtrType)
	return value.makePointee()
}

func (tm *TypeMap) funcLLVMType(f *types.Func) llvm.Type {
	param_types := make([]llvm.Type, 0)

	// Add receiver parameter.
	if f.Recv != nil {
		recv_type := f.Recv.Type.(types.Type)
		param_types = append(param_types, tm.ToLLVM(recv_type))
	}

	for _, param := range f.Params {
		param_type := param.Type.(types.Type)
		param_types = append(param_types, tm.ToLLVM(param_type))
	}

	var return_type llvm.Type
	switch len(f.Results) {
	case 0:
		return_type = llvm.VoidType()
	case 1:
		return_type = tm.ToLLVM(f.Results[0].Type.(types.Type))
	default:
		elements := make([]llvm.Type, len(f.Results))
		for i, result := range f.Results {
			elements[i] = tm.ToLLVM(result.Type.(types.Type))
		}
		return_type = llvm.StructType(elements, false)
	}

	fn_type := llvm.FunctionType(return_type, param_types, false)
	return llvm.PointerType(fn_type, 0)
}

func (c *compiler) defineMemcpyFunction(fn llvm.Value) {
	entry := llvm.AddBasicBlock(fn, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	dst, src, size := fn.Param(0), fn.Param(1), fn.Param(2)

	pint8 := llvm.PointerType(llvm.Int8Type(), 0)
	dst = c.builder.CreateIntToPtr(dst, pint8, "")
	src = c.builder.CreateIntToPtr(src, pint8, "")

	sizeType := size.Type()
	sizeBits := sizeType.IntTypeWidth()
	memcpyName := "llvm.memcpy.p0i8.p0i8.i" + strconv.Itoa(sizeBits)
	memcpy := c.module.NamedFunction(memcpyName)
	if memcpy.IsNil() {
		paramtypes := []llvm.Type{
			pint8, pint8, size.Type(), llvm.Int32Type(), llvm.Int1Type()}
		memcpyType := llvm.FunctionType(llvm.VoidType(), paramtypes, false)
		memcpy = llvm.AddFunction(c.module.Module, memcpyName, memcpyType)
	}

	args := []llvm.Value{
		dst, src, size,
		llvm.ConstInt(llvm.Int32Type(), 1, false), // single byte alignment
		llvm.ConstInt(llvm.Int1Type(), 0, false),  // not volatile
	}
	c.builder.CreateCall(memcpy, args, "")
	c.builder.CreateRetVoid()
}

func (c *compiler) compareStrings(lhs, rhs *LLVMValue, op token.Token) *LLVMValue {
	strcmp := c.module.Module.NamedFunction("runtime.strcmp")
	if strcmp.IsNil() {
		string_type := c.types.ToLLVM(types.String)
		param_types := []llvm.Type{string_type, string_type}
		func_type := llvm.FunctionType(llvm.Int32Type(), param_types, false)
		strcmp = llvm.AddFunction(c.module.Module, "runtime.strcmp", func_type)
	}
	args := []llvm.Value{lhs.LLVMValue(), rhs.LLVMValue()}
	result := c.builder.CreateCall(strcmp, args, "")
	zero := llvm.ConstNull(llvm.Int32Type())
	var pred llvm.IntPredicate
	switch op {
	case token.EQL:
		pred = llvm.IntEQ
	case token.LSS:
		pred = llvm.IntSLT
	case token.GTR:
		pred = llvm.IntSGT
	case token.LEQ:
		pred = llvm.IntSLE
	case token.GEQ:
		pred = llvm.IntSGE
	case token.NEQ:
		panic("NEQ is handled in LLVMValue.BinaryOp")
	default:
		panic("unreachable")
	}
	result = c.builder.CreateICmp(pred, result, zero, "")
	return c.NewLLVMValue(result, types.Bool)
}

// contextFunction creates a wrapper function that
// has the same signature as the specified function,
// but has an additional first parameter that accepts
// and ignores the function context value.
//
// contextFunction must be called with a global function
// pointer.
func contextFunction(c *compiler, f *LLVMValue) *LLVMValue {
	defer c.builder.SetInsertPointAtEnd(c.builder.GetInsertBlock())
	resultType := c.llvmtypes.ToLLVM(f.Type())
	fnptr := f.LLVMValue()
	contextType := resultType.StructElementTypes()[1]
	llfntyp := fnptr.Type().ElementType()
	llfntyp = llvm.FunctionType(
		llfntyp.ReturnType(),
		append([]llvm.Type{contextType}, llfntyp.ParamTypes()...),
		llfntyp.IsFunctionVarArg(),
	)
	wrapper := llvm.AddFunction(c.module.Module, fnptr.Name()+".ctx", llfntyp)
	wrapper.SetLinkage(llvm.PrivateLinkage)
	entry := llvm.AddBasicBlock(wrapper, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	args := make([]llvm.Value, len(llfntyp.ParamTypes())-1)
	for i := range args {
		args[i] = wrapper.Param(i + 1)
	}
	result := c.builder.CreateCall(fnptr, args, "")
	switch nresults := f.Type().(*types.Signature).Results().Len(); nresults {
	case 0:
		c.builder.CreateRetVoid()
	case 1:
		c.builder.CreateRet(result)
	default:
		results := make([]llvm.Value, nresults)
		for i := range results {
			results[i] = c.builder.CreateExtractValue(result, i, "")
		}
		c.builder.CreateAggregateRet(results)
	}
	return c.NewValue(wrapper, f.Type())
}

// interfacesEqual compares two interfaces for equality, returning
// a dynamic boolean value.
func (lhs *LLVMValue) compareI2I(rhs *LLVMValue) Value {
	c := lhs.compiler
	b := c.builder

	lhsValue := b.CreateExtractValue(lhs.LLVMValue(), 0, "")
	rhsValue := b.CreateExtractValue(rhs.LLVMValue(), 0, "")
	lhsType := b.CreateExtractValue(lhs.LLVMValue(), 1, "")
	rhsType := b.CreateExtractValue(rhs.LLVMValue(), 1, "")

	llvmUintptr := c.target.IntPtrType()
	runtimeCompareI2I := c.module.Module.NamedFunction("runtime.compareI2I")
	if runtimeCompareI2I.IsNil() {
		args := []llvm.Type{llvmUintptr, llvmUintptr, llvmUintptr, llvmUintptr}
		functype := llvm.FunctionType(llvm.Int1Type(), args, false)
		runtimeCompareI2I = llvm.AddFunction(
			c.module.Module, "runtime.compareI2I", functype)
	}

	args := []llvm.Value{
		c.builder.CreatePtrToInt(lhsType, llvmUintptr, ""),
		c.builder.CreatePtrToInt(rhsType, llvmUintptr, ""),
		c.builder.CreatePtrToInt(lhsValue, llvmUintptr, ""),
		c.builder.CreatePtrToInt(rhsValue, llvmUintptr, ""),
	}

	result := c.builder.CreateCall(runtimeCompareI2I, args, "")
	return c.NewLLVMValue(result, types.Bool)
}

func NewTypeMap(module llvm.Module, target llvm.TargetData, exprTypes map[ast.Expr]types.Type) *TypeMap {
	tm := &TypeMap{module: module, target: target, expr: exprTypes}
	tm.types = make(map[types.Type]llvm.Type)
	tm.runtime = make(map[types.Type]llvm.Value)

	// Load "reflect.go", and generate LLVM types for the runtime type
	// structures.
	pkg, err := parseReflect()
	if err != nil {
		panic(err) // FIXME return err
	}
	objToLLVMType := func(name string) llvm.Type {
		obj := pkg.Scope.Lookup(name)
		return tm.ToLLVM(obj.Type.(types.Type))
	}
	tm.runtimeCommonType = objToLLVMType("commonType")
	tm.runtimeUncommonType = objToLLVMType("uncommonType")
	tm.runtimeArrayType = objToLLVMType("arrayType")
	tm.runtimeChanType = objToLLVMType("chanType")
	tm.runtimeFuncType = objToLLVMType("funcType")
	tm.runtimeInterfaceType = objToLLVMType("interfaceType")
	tm.runtimeMapType = objToLLVMType("mapType")
	tm.runtimePtrType = objToLLVMType("ptrType")
	tm.runtimeSliceType = objToLLVMType("sliceType")
	tm.runtimeStructType = objToLLVMType("structType")

	// Types for algorithms. See 'runtime/runtime.h'.
	uintptrType := tm.target.IntPtrType()
	voidPtrType := llvm.PointerType(llvm.Int8Type(), 0)
	boolType := llvm.Int1Type()

	// Create runtime algorithm function types.
	params := []llvm.Type{
		llvm.PointerType(uintptrType, 0), uintptrType, voidPtrType}
	tm.hashAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)
	params = []llvm.Type{
		llvm.PointerType(boolType, 0), uintptrType, voidPtrType, voidPtrType}
	tm.equalAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)
	params = []llvm.Type{uintptrType, voidPtrType}
	tm.printAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)
	params = []llvm.Type{uintptrType, voidPtrType, voidPtrType}
	tm.copyAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)

	return tm
}

func (tm *LLVMTypeMap) funcLLVMType(tstr string, f *types.Signature) llvm.Type {
	typ, ok := tm.types[tstr]
	if !ok {
		// If there's a receiver change the receiver to an
		// additional (first) parameter, and take the value of
		// the resulting signature instead.
		var param_types []llvm.Type
		if recv := f.Recv(); recv != nil {
			params := f.Params()
			paramvars := make([]*types.Var, int(params.Len()+1))
			paramvars[0] = recv
			for i := 0; i < int(params.Len()); i++ {
				paramvars[i+1] = params.At(i)
			}
			params = types.NewTuple(paramvars...)
			f := types.NewSignature(nil, params, f.Results(), f.IsVariadic())
			return tm.ToLLVM(f)
		}

		typ = llvm.GlobalContext().StructCreateNamed("")
		tm.types[tstr] = typ

		params := f.Params()
		nparams := int(params.Len())
		for i := 0; i < nparams; i++ {
			typ := params.At(i).Type()
			if f.IsVariadic() && i == nparams-1 {
				typ = types.NewSlice(typ)
			}
			llvmtyp := tm.ToLLVM(typ)
			param_types = append(param_types, llvmtyp)
		}

		var return_type llvm.Type
		results := f.Results()
		switch nresults := int(results.Len()); nresults {
		case 0:
			return_type = llvm.VoidType()
		case 1:
			return_type = tm.ToLLVM(results.At(0).Type())
		default:
			elements := make([]llvm.Type, nresults)
			for i := range elements {
				result := results.At(i)
				elements[i] = tm.ToLLVM(result.Type())
			}
			return_type = llvm.StructType(elements, false)
		}

		fntyp := llvm.FunctionType(return_type, param_types, false)
		fnptrtyp := llvm.PointerType(fntyp, 0)
		i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
		elements := []llvm.Type{fnptrtyp, i8ptr} // func, closure
		typ.StructSetBody(elements, false)
	}
	return typ
}

func newAlgorithmMap(m llvm.Module, runtime *runtimeInterface, target llvm.TargetData) *algorithmMap {
	am := &algorithmMap{
		module:  m,
		runtime: runtime,
	}
	uintptrType := target.IntPtrType()
	voidPtrType := llvm.PointerType(llvm.Int8Type(), 0)
	boolType := llvm.Int1Type()
	params := []llvm.Type{uintptrType, voidPtrType}
	am.hashAlgFunctionType = llvm.FunctionType(uintptrType, params, false)
	params = []llvm.Type{uintptrType, uintptrType, uintptrType}
	am.equalAlgFunctionType = llvm.FunctionType(boolType, params, false)
	params = []llvm.Type{uintptrType, voidPtrType}
	am.printAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)
	params = []llvm.Type{uintptrType, voidPtrType, voidPtrType}
	am.copyAlgFunctionType = llvm.FunctionType(llvm.VoidType(), params, false)
	return am
}

func getPrintf(module llvm.Module) llvm.Value {
	printf := module.NamedFunction("printf")
	if printf.IsNil() {
		charPtr := llvm.PointerType(llvm.Int8Type(), 0)
		ftyp := llvm.FunctionType(llvm.Int32Type(), []llvm.Type{charPtr}, true)
		printf = llvm.AddFunction(module, "printf", ftyp)
		printf.SetFunctionCallConv(llvm.CCallConv)
	}
	return printf
}

func getFflush(module llvm.Module) llvm.Value {
	fflush := module.NamedFunction("fflush")
	if fflush.IsNil() {
		voidPtr := llvm.PointerType(llvm.Int8Type(), 0)
		ftyp := llvm.FunctionType(llvm.Int32Type(), []llvm.Type{voidPtr}, false)
		fflush = llvm.AddFunction(module, "fflush", ftyp)
		fflush.SetFunctionCallConv(llvm.CCallConv)
	}
	return fflush
}

func (c *compiler) createMainFunction() error {
	// In a PNaCl program (plugin), there should not be a "main.main";
	// instead, we expect a "main.CreateModule" function.
	// See pkg/nacl/ppapi/ppapi.go for more details.
	mainMain := c.module.NamedFunction("main.main")
	/*
		if c.pnacl {
			// PNaCl's libppapi_stub.a implements "main", which simply
			// calls through to PpapiPluginMain. We define our own "main"
			// so that we can capture argc/argv.
			if !mainMain.IsNil() {
				return fmt.Errorf("Found main.main")
			}
			pluginMain := c.RuntimeFunction("PpapiPluginMain", "func() int32")

			// Synthesise a main which has no return value. We could cast
			// PpapiPluginMain, but this is potentially unsafe as its
			// calling convention is unspecified.
			ftyp := llvm.FunctionType(llvm.VoidType(), nil, false)
			mainMain = llvm.AddFunction(c.module.Module, "main.main", ftyp)
			entry := llvm.AddBasicBlock(mainMain, "entry")
			c.builder.SetInsertPointAtEnd(entry)
			c.builder.CreateCall(pluginMain, nil, "")
			c.builder.CreateRetVoid()
		} else */{
		mainMain = c.module.NamedFunction("main.main")
	}

	if mainMain.IsNil() {
		return fmt.Errorf("Could not find main.main")
	}

	// runtime.main is called by main, with argc, argv, argp,
	// and a pointer to main.main, which must be a niladic
	// function with no result.
	runtimeMain := c.runtime.main.LLVMValue()

	ptrptr := llvm.PointerType(llvm.PointerType(llvm.Int8Type(), 0), 0)
	ftyp := llvm.FunctionType(llvm.Int32Type(), []llvm.Type{llvm.Int32Type(), ptrptr, ptrptr}, true)
	main := llvm.AddFunction(c.module.Module, "main", ftyp)

	c.builder.SetCurrentDebugLocation(c.debug.MDNode(nil))
	entry := llvm.AddBasicBlock(main, "entry")
	c.builder.SetInsertPointAtEnd(entry)
	runtimeMainParamTypes := runtimeMain.Type().ElementType().ParamTypes()
	args := []llvm.Value{
		main.Param(0), // argc
		main.Param(1), // argv
		main.Param(2), // argp
		c.builder.CreateBitCast(mainMain, runtimeMainParamTypes[3], ""),
	}
	result := c.builder.CreateCall(runtimeMain, args, "")
	c.builder.CreateRet(result)
	return nil
}

func (c *compiler) concatenateStrings(lhs, rhs *LLVMValue) *LLVMValue {
	strcat := c.module.Module.NamedFunction("runtime.strcat")
	if strcat.IsNil() {
		string_type := c.types.ToLLVM(types.String)
		param_types := []llvm.Type{string_type, string_type}
		func_type := llvm.FunctionType(string_type, param_types, false)
		strcat = llvm.AddFunction(c.module.Module, "runtime.strcat", func_type)
	}
	args := []llvm.Value{lhs.LLVMValue(), rhs.LLVMValue()}
	result := c.builder.CreateCall(strcat, args, "")
	return c.NewLLVMValue(result, types.String)
}

func (tm *llvmTypeMap) funcLLVMType(f *types.Signature, name string) llvm.Type {
	// If there's a receiver change the receiver to an
	// additional (first) parameter, and take the value of
	// the resulting signature instead.
	if recv := f.Recv(); recv != nil {
		params := f.Params()
		paramvars := make([]*types.Var, int(params.Len()+1))
		paramvars[0] = recv
		for i := 0; i < int(params.Len()); i++ {
			paramvars[i+1] = params.At(i)
		}
		params = types.NewTuple(paramvars...)
		f := types.NewSignature(nil, nil, params, f.Results(), f.Variadic())
		return tm.toLLVM(f, name)
	}

	if typ, ok := tm.types.At(f).(llvm.Type); ok {
		return typ
	}
	typ := llvm.GlobalContext().StructCreateNamed(name)
	tm.types.Set(f, typ)

	params := f.Params()
	param_types := make([]llvm.Type, params.Len())
	for i := range param_types {
		llvmtyp := tm.ToLLVM(params.At(i).Type())
		param_types[i] = llvmtyp
	}

	var return_type llvm.Type
	results := f.Results()
	switch nresults := int(results.Len()); nresults {
	case 0:
		return_type = llvm.VoidType()
	case 1:
		return_type = tm.ToLLVM(results.At(0).Type())
	default:
		elements := make([]llvm.Type, nresults)
		for i := range elements {
			result := results.At(i)
			elements[i] = tm.ToLLVM(result.Type())
		}
		return_type = llvm.StructType(elements, false)
	}

	fntyp := llvm.FunctionType(return_type, param_types, false)
	fnptrtyp := llvm.PointerType(fntyp, 0)
	i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
	elements := []llvm.Type{fnptrtyp, i8ptr} // func, closure
	typ.StructSetBody(elements, false)
	return typ
}

func (c *compiler) VisitFuncProtoDecl(f *ast.FuncDecl) *LLVMValue {
	if f.Name.Obj != nil {
		if result, ok := f.Name.Obj.Data.(*LLVMValue); ok {
			return result
		}
	}

	var ftyp *types.Func
	fname := f.Name.String()
	if f.Recv == nil && fname == "init" {
		// Make "init" functions anonymous.
		fname = ""
		// "init" functions aren't recorded by the parser, so f.Name.Obj is
		// not set.
		ftyp = &types.Func{ /* no params or result */ }
	} else {
		ftyp = f.Name.Obj.Type.(*types.Func)
		if ftyp.Recv != nil {
			recv := ftyp.Recv.Type.(types.Type)
			fname = fmt.Sprintf("%s.%s", recv, fname)
		} else if c.module.Name != "main" || fname != "main" {
			pkgname := c.pkgmap[f.Name.Obj]
			fname = pkgname + "." + fname
		}
	}

	// gcimporter may produce multiple AST objects for the same function.
	fn := c.module.Module.NamedFunction(fname)
	if fn.IsNil() {
		llvmftyp := c.types.ToLLVM(ftyp).ElementType()
		fn = llvm.AddFunction(c.module.Module, fname, llvmftyp)
		if ftyp.Recv != nil {
			// Create an interface function if the receiver is
			// not a pointer type.
			recvtyp := ftyp.Recv.Type.(types.Type)
			if _, ptr := recvtyp.(*types.Pointer); !ptr {
				returntyp := llvmftyp.ReturnType()
				paramtypes := llvmftyp.ParamTypes()
				paramtypes[0] = llvm.PointerType(paramtypes[0], 0)
				ifntyp := llvm.FunctionType(returntyp, paramtypes, false)
				llvm.AddFunction(c.module.Module, "*"+fname, ifntyp)
			}
		}
	}
	result := c.NewLLVMValue(fn, ftyp)
	if f.Name.Obj != nil {
		f.Name.Obj.Data = result
		f.Name.Obj.Type = ftyp
	}
	return result
}

func (c *compiler) VisitAppend(expr *ast.CallExpr) Value {
	// TODO handle ellpisis arg
	s := c.VisitExpr(expr.Args[0])
	elem := c.VisitExpr(expr.Args[1])

	appendName := "runtime.sliceappend"
	appendFun := c.module.NamedFunction(appendName)
	uintptrTyp := c.target.IntPtrType()
	var i8slice llvm.Type
	if appendFun.IsNil() {
		i8slice = c.types.ToLLVM(&types.Slice{Elt: types.Int8})
		args := []llvm.Type{uintptrTyp, i8slice, i8slice}
		appendFunTyp := llvm.FunctionType(i8slice, args, false)
		appendFun = llvm.AddFunction(c.module.Module, appendName, appendFunTyp)
	} else {
		i8slice = appendFun.Type().ReturnType()
	}
	i8ptr := i8slice.StructElementTypes()[0]

	// Coerce first argument into an []int8.
	a_ := s.LLVMValue()
	sliceTyp := a_.Type()
	a := c.coerceSlice(a_, i8slice)

	// Construct a fresh []int8 for the temporary slice.
	b_ := elem.LLVMValue()
	one := llvm.ConstInt(llvm.Int32Type(), 1, false)
	mem := c.builder.CreateAlloca(elem.LLVMValue().Type(), "")
	c.builder.CreateStore(b_, mem)
	b := llvm.Undef(i8slice)
	b = c.builder.CreateInsertValue(b, c.builder.CreateBitCast(mem, i8ptr, ""), 0, "")
	b = c.builder.CreateInsertValue(b, one, 1, "")
	b = c.builder.CreateInsertValue(b, one, 2, "")

	// Call runtime function, then coerce the result.
	runtimeTyp := c.types.ToRuntime(s.Type())
	runtimeTyp = c.builder.CreatePtrToInt(runtimeTyp, uintptrTyp, "")
	args := []llvm.Value{runtimeTyp, a, b}
	result := c.builder.CreateCall(appendFun, args, "")
	return c.NewLLVMValue(c.coerceSlice(result, sliceTyp), s.Type())
}