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