// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"cmd/compile/internal/types"
	"fmt"
)

// A place that an ssa variable can reside.
type Location interface {
	Name() string // name to use in assembly templates: %rax, 16(%rsp), ...
}

// A Register is a machine register, like %rax.
// They are numbered densely from 0 (for each architecture).
type Register struct {
	num    int32
	objNum int16 // register number from cmd/internal/obj/$ARCH
	name   string
}

func (r *Register) Name() string {
	return r.name
}

// A LocalSlot is a location in the stack frame.
// It is (possibly a subpiece of) a PPARAM, PPARAMOUT, or PAUTO ONAME node.
type LocalSlot struct {
	N    GCNode      // an ONAME *gc.Node representing a variable on the stack
	Type *types.Type // type of slot
	Off  int64       // offset of slot in N
}

func (s LocalSlot) Name() string {
	if s.Off == 0 {
		return fmt.Sprintf("%v[%v]", s.N, s.Type)
	}
	return fmt.Sprintf("%v+%d[%v]", s.N, s.Off, s.Type)
}

type LocPair [2]Location

func (t LocPair) Name() string {
	n0, n1 := "nil", "nil"
	if t[0] != nil {
		n0 = t[0].Name()
	}
	if t[1] != nil {
		n1 = t[1].Name()
	}
	return fmt.Sprintf("<%s,%s>", n0, n1)
}