cmd/compile/internal/ir: remove OrigNode

The OrigNode functionality used to be relevant to the typecheck
frontend, because we wanted to report errors using the same syntax as
the user originally wrote. However, now that types2 handles all
spec-required error diagnostics, there's no need to preserve original
nodes anymore.

Change-Id: I64a0540b8952513913021e7b84d165beb1f9f801
Reviewed-on: https://go-review.googlesource.com/c/go/+/526397
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/cmd/compile/internal/ir/copy.go b/src/cmd/compile/internal/ir/copy.go
index be57a8fbc6d0b649d30aa755b9ed915ef912c4b5..9d3a13665739635f2622c63d7ee7b88b9ad649b7 100644 (file)
--- a/src/cmd/compile/internal/ir/copy.go
+++ b/src/cmd/compile/internal/ir/copy.go
@@ -5,71 +5,26 @@
 package ir
 
 import (
-       "cmd/compile/internal/base"
        "cmd/internal/src"
 )
 
-// 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.
+// Orig returns n.
 //
-// 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)
-}
-
-// origNode may be embedded into a Node to make it implement OrigNode.
-type origNode struct {
-       orig Node `mknode:"-"`
-}
-
-func (n *origNode) Orig() Node     { return n.orig }
-func (n *origNode) SetOrig(o Node) { n.orig = o }
-
-// Orig returns the “original” node for n.
-// If n implements OrigNode, Orig returns n.Orig().
-// Otherwise Orig returns n itself.
+// TODO(mdempsky): Remove.
 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,
-// breaking any Orig link to any other nodes.
+// SepCopy returns a shallow copy of n.
+//
+// TODO(mdempsky): Replace with Copy.
 func SepCopy(n Node) Node {
-       n = n.copy()
-       if n, ok := n.(OrigNode); ok {
-               n.SetOrig(n)
-       }
-       return n
+       return n.copy()
 }
 
 // Copy returns a shallow copy of n.
-// If Orig(n) == n, then Orig(Copy(n)) == the copy.
-// Otherwise the Orig link is preserved as well.
-//
-// The specific semantics surrounding Orig are subtle but right for most uses.
-// See issues #26855 and #27765 for pitfalls.
 func Copy(n Node) Node {
-       c := n.copy()
-       if n, ok := n.(OrigNode); ok && n.Orig() == n {
-               c.(OrigNode).SetOrig(c)
-       }
-       return c
+       return n.copy()
 }
 
 // DeepCopy returns a “deep” copy of n, with its entire structure copied

diff --git a/src/cmd/compile/internal/ir/expr.go b/src/cmd/compile/internal/ir/expr.go
index 573021a554bae142eaaa3268c8ec2e1b28a11949..abea185dd3fcec3ecd669ee79c70485592872ee9 100644 (file)
--- a/src/cmd/compile/internal/ir/expr.go
+++ b/src/cmd/compile/internal/ir/expr.go
@@ -188,7 +188,6 @@ func (n *BinaryExpr) SetOp(op Op) {
 // A CallExpr is a function call X(Args).
 type CallExpr struct {
        miniExpr
-       origNode
        X         Node
        Args      Nodes
        RType     Node    `mknode:"-"` // see reflectdata/helpers.go
@@ -200,7 +199,6 @@ type CallExpr struct {
 func NewCallExpr(pos src.XPos, op Op, fun Node, args []Node) *CallExpr {
        n := &CallExpr{X: fun}
        n.pos = pos
-       n.orig = n
        n.SetOp(op)
        n.Args = args
        return n
@@ -234,7 +232,6 @@ type ClosureExpr struct {
 // Before type-checking, the type is Ntype.
 type CompLitExpr struct {
        miniExpr
-       origNode
        List     Nodes // initialized values
        RType    Node  `mknode:"-"` // *runtime._type for OMAPLIT map types
        Prealloc *Name
@@ -251,7 +248,6 @@ func NewCompLitExpr(pos src.XPos, op Op, typ *types.Type, list []Node) *CompLitE
        if typ != nil {
                n.SetType(typ)
        }
-       n.orig = n
        return n
 }
 

diff --git a/src/cmd/compile/internal/ir/stmt.go b/src/cmd/compile/internal/ir/stmt.go
index 01d218ecc415203f65f0fb2a03afa5a40a6c7036..3e925b9db2e78823ff933a0158d3a6688022b93a 100644 (file)
--- a/src/cmd/compile/internal/ir/stmt.go
+++ b/src/cmd/compile/internal/ir/stmt.go
@@ -373,15 +373,13 @@ func NewRangeStmt(pos src.XPos, key, value, x Node, body []Node, distinctVars bo
 // A ReturnStmt is a return statement.
 type ReturnStmt struct {
        miniStmt
-       origNode       // for typecheckargs rewrite
-       Results  Nodes // return list
+       Results Nodes // return list
 }
 
 func NewReturnStmt(pos src.XPos, results []Node) *ReturnStmt {
        n := &ReturnStmt{}
        n.pos = pos
        n.op = ORETURN
-       n.orig = n
        n.Results = results
        return n
 }

diff --git a/src/cmd/compile/internal/typecheck/expr.go b/src/cmd/compile/internal/typecheck/expr.go
index 89c37d373e9b9357d81ae848e831a89110b42719..53d0cbf96dec645d8dd2e4b3a3c2c7c89dfd9be7 100644 (file)
--- a/src/cmd/compile/internal/typecheck/expr.go
+++ b/src/cmd/compile/internal/typecheck/expr.go
@@ -169,9 +169,6 @@ func tcCompLit(n *ir.CompLitExpr) (res ir.Node) {
                base.Pos = lno
        }()
 
-       // Save original node (including n.Right)
-       n.SetOrig(ir.Copy(n))
-
        ir.SetPos(n)
 
        t := n.Type()

diff --git a/src/cmd/compile/internal/typecheck/typecheck.go b/src/cmd/compile/internal/typecheck/typecheck.go
index ef8ca7705dd59d7f172cd2837d73ffffd463f1c1..1cd5d883924b0a4e8a8a7881300305d5b7b6a420 100644 (file)
--- a/src/cmd/compile/internal/typecheck/typecheck.go
+++ b/src/cmd/compile/internal/typecheck/typecheck.go
@@ -624,11 +624,6 @@ func typecheckargs(n ir.InitNode) {
                return
        }
 
-       // Save n as n.Orig for fmt.go.
-       if ir.Orig(n) == n {
-               n.(ir.OrigNode).SetOrig(ir.SepCopy(n))
-       }
-
        // Rewrite f(g()) into t1, t2, ... = g(); f(t1, t2, ...).
        RewriteMultiValueCall(n, list[0])
 }