From 60fee0153ff9ae2f03e5db9fa8cf700cd953bf8d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Mart=C3=AD?= <mvdan@mvdan.cc>
Date: Thu, 5 Apr 2018 14:45:38 +0100
Subject: [PATCH] cmd/compile: remove last manual node copies
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When I added the Node.copy method, I converted most of the occurrences
but missed a few.

One of them, used only for gdata, was an unnecessary copy given that
gdata does not modify the node it is passed.

No allocation changes in compilebench.

Passes toolstash -cmp on std cmd.

Change-Id: I7fba5212377b75c6d6b3785e594a30568ff0732e
Reviewed-on: https://go-review.googlesource.com/104937
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
---
 src/cmd/compile/internal/gc/const.go |  5 ++---
 src/cmd/compile/internal/gc/sinit.go | 17 ++++++++---------
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/src/cmd/compile/internal/gc/const.go b/src/cmd/compile/internal/gc/const.go
index 27c2e14d76..a239cd6d3e 100644
--- a/src/cmd/compile/internal/gc/const.go
+++ b/src/cmd/compile/internal/gc/const.go
@@ -1184,9 +1184,8 @@ func setconst(n *Node, v Val) {
 	// Ensure n.Orig still points to a semantically-equivalent
 	// expression after we rewrite n into a constant.
 	if n.Orig == n {
-		var ncopy Node
-		n.Orig = &ncopy
-		ncopy = *n
+		n.Orig = n.copy()
+		n.Orig.Orig = n.Orig
 	}
 
 	*n = Node{
diff --git a/src/cmd/compile/internal/gc/sinit.go b/src/cmd/compile/internal/gc/sinit.go
index edd098b1ec..d083fc4208 100644
--- a/src/cmd/compile/internal/gc/sinit.go
+++ b/src/cmd/compile/internal/gc/sinit.go
@@ -472,8 +472,7 @@ func staticassign(l *Node, r *Node, out *[]*Node) bool {
 			}
 			// Closures with no captured variables are globals,
 			// so the assignment can be done at link time.
-			n := *l
-			gdata(&n, r.Func.Closure.Func.Nname, Widthptr)
+			gdata(l, r.Func.Closure.Func.Nname, Widthptr)
 			return true
 		}
 		closuredebugruntimecheck(r)
@@ -504,10 +503,10 @@ func staticassign(l *Node, r *Node, out *[]*Node) bool {
 		}
 
 		// Create a copy of l to modify while we emit data.
-		n := *l
+		n := l.copy()
 
 		// Emit itab, advance offset.
-		gdata(&n, itab, Widthptr)
+		gdata(n, itab, Widthptr)
 		n.Xoffset += int64(Widthptr)
 
 		// Emit data.
@@ -519,10 +518,10 @@ func staticassign(l *Node, r *Node, out *[]*Node) bool {
 			// Copy val directly into n.
 			n.Type = val.Type
 			setlineno(val)
-			a := n
-			a.Orig = &a
-			if !staticassign(&a, val, out) {
-				*out = append(*out, nod(OAS, &a, val))
+			a := n.copy()
+			a.Orig = a
+			if !staticassign(a, val, out) {
+				*out = append(*out, nod(OAS, a, val))
 			}
 		} else {
 			// Construct temp to hold val, write pointer to temp into n.
@@ -533,7 +532,7 @@ func staticassign(l *Node, r *Node, out *[]*Node) bool {
 			}
 			ptr := nod(OADDR, a, nil)
 			n.Type = types.NewPtr(val.Type)
-			gdata(&n, ptr, Widthptr)
+			gdata(n, ptr, Widthptr)
 		}
 
 		return true