src/cmd/internal/ssa/location.go

// 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 (
	"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.
type Register struct {
	name string
}

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

// A LocalSlot is a location in the stack frame.
type LocalSlot struct {
	idx int64 // offset in locals area (distance down from FP == caller's SP)
}

func (s *LocalSlot) Name() string {
	return fmt.Sprintf("-%d(FP)", s.idx)
}

// An ArgSlot is a location in the parents' stack frame where it passed us an argument.
type ArgSlot struct {
	idx int64 // offset in argument area
}

// A CalleeSlot is a location in the stack frame where we pass an argument to a callee.
type CalleeSlot struct {
	idx int64 // offset in callee area
}