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// Copyright 2020 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.
//go:generate go run mknode.go
package ir
import (
"cmd/compile/internal/types"
"cmd/internal/src"
"fmt"
"go/constant"
)
// A miniNode is a minimal node implementation,
// meant to be embedded as the first field in a larger node implementation,
// at a cost of 8 bytes.
//
// A miniNode is NOT a valid Node by itself: the embedding struct
// must at the least provide:
//
// func (n *MyNode) String() string { return fmt.Sprint(n) }
// func (n *MyNode) rawCopy() Node { c := *n; return &c }
// func (n *MyNode) Format(s fmt.State, verb rune) { FmtNode(n, s, verb) }
//
// The embedding struct should also fill in n.op in its constructor,
// for more useful panic messages when invalid methods are called,
// instead of implementing Op itself.
type miniNode struct {
pos src.XPos // uint32
op Op // uint8
bits bitset8
esc uint16
}
// posOr returns pos if known, or else n.pos.
// For use in DeepCopy.
func (n *miniNode) posOr(pos src.XPos) src.XPos {
if pos.IsKnown() {
return pos
}
return n.pos
}
// op can be read, but not written.
// An embedding implementation can provide a SetOp if desired.
// (The panicking SetOp is with the other panics below.)
func (n *miniNode) Op() Op { return n.op }
func (n *miniNode) Pos() src.XPos { return n.pos }
func (n *miniNode) SetPos(x src.XPos) { n.pos = x }
func (n *miniNode) Esc() uint16 { return n.esc }
func (n *miniNode) SetEsc(x uint16) { n.esc = x }
const (
miniTypecheckShift = 0
miniWalked = 1 << 2 // to prevent/catch re-walking
)
func (n *miniNode) Typecheck() uint8 { return n.bits.get2(miniTypecheckShift) }
func (n *miniNode) SetTypecheck(x uint8) {
if x > 2 {
panic(fmt.Sprintf("cannot SetTypecheck %d", x))
}
n.bits.set2(miniTypecheckShift, x)
}
func (n *miniNode) Walked() bool { return n.bits&miniWalked != 0 }
func (n *miniNode) SetWalked(x bool) { n.bits.set(miniWalked, x) }
// Empty, immutable graph structure.
func (n *miniNode) Init() Nodes { return Nodes{} }
// Additional functionality unavailable.
func (n *miniNode) no(name string) string { return "cannot " + name + " on " + n.op.String() }
func (n *miniNode) Type() *types.Type { return nil }
func (n *miniNode) SetType(*types.Type) { panic(n.no("SetType")) }
func (n *miniNode) Name() *Name { return nil }
func (n *miniNode) Sym() *types.Sym { return nil }
func (n *miniNode) Val() constant.Value { panic(n.no("Val")) }
func (n *miniNode) SetVal(v constant.Value) { panic(n.no("SetVal")) }
func (n *miniNode) NonNil() bool { return false }
func (n *miniNode) MarkNonNil() { panic(n.no("MarkNonNil")) }
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