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[dev.regabi] cmd/compile: remove Orig, SetOrig from Node interface

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These are only needed for a few opcodes, and we can avoid
wasting storage in every implementation by using the extension
interface pattern with a helper function for access.

Of course, in the current codebase, there is only one Node
implementation (*node) and it has these methods, so there
is no danger of a functional change in this particular CL.

Passes buildall w/ toolstash -cmp.

Change-Id: I440c6c232f1fe7b56b852a00dc530f8f49a6b12d
Reviewed-on: https://go-review.googlesource.com/c/go/+/274089
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Russ Cox 2020-11-28 00:36:44 -05:00
parent 79a3d5ce15
commit 171787efcd
9 changed files with 52 additions and 24 deletions
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42
src/cmd/compile/internal/ir/node.go
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@ -35,8 +35,6 @@ type Node interface {
// Abstract graph structure, for generic traversals.
Op() Op
SetOp(x Op)
Orig() Node
SetOrig(x Node)
SubOp() Op
SetSubOp(x Op)
Left() Node
@ -1616,11 +1614,41 @@ func (n *node) RawCopy() Node {
return &copy
}
// A Node may implement the Orig and SetOrig method to
// maintain a pointer to the "unrewritten" form of a Node.
// If a Node does not implement OrigNode, it is its own Orig.
//
// Note that both SepCopy and Copy have definitions compatible
// with a Node that does not implement OrigNode: such a Node
// is its own Orig, and in that case, that's what both want to return
// anyway (SepCopy unconditionally, and Copy only when the input
// is its own Orig as well, but if the output does not implement
// OrigNode, then neither does the input, making the condition true).
type OrigNode interface {
Node
Orig() Node
SetOrig(Node)
}
func Orig(n Node) Node {
if n, ok := n.(OrigNode); ok {
o := n.Orig()
if o == nil {
Dump("Orig nil", n)
base.Fatalf("Orig returned nil")
}
return o
}
return n
}
// sepcopy returns a separate shallow copy of n, with the copy's
// Orig pointing to itself.
func SepCopy(n Node) Node {
n = n.RawCopy()
n.SetOrig(n)
if n, ok := n.(OrigNode); ok {
n.SetOrig(n)
}
return n
}
@ -1633,8 +1661,8 @@ func SepCopy(n Node) Node {
// messages; see issues #26855, #27765).
func Copy(n Node) Node {
copy := n.RawCopy()
if n.Orig() == n {
copy.SetOrig(copy)
if n, ok := n.(OrigNode); ok && n.Orig() == n {
copy.(OrigNode).SetOrig(copy)
}
return copy
}
@ -1643,7 +1671,7 @@ func Copy(n Node) Node {
func IsNil(n Node) bool {
// Check n.Orig because constant propagation may produce typed nil constants,
// which don't exist in the Go spec.
return n.Orig().Op() == ONIL
return Orig(n).Op() == ONIL
}
func IsBlank(n Node) bool {
@ -1664,7 +1692,7 @@ func Nod(op Op, nleft, nright Node) Node {
}
func NodAt(pos src.XPos, op Op, nleft, nright Node) Node {
var n Node
var n *node
switch op {
case ODCLFUNC:
var x struct {