cmd/compile: remove pointer arithmetic

Change-Id: Ie4bab0b74d5a4e1aecd8501a48176b2e9a3d8c42
Reviewed-on: https://go-review.googlesource.com/c/76311
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/cmd/compile/internal/gc/range.go

@@ -286,13 +286,7 @@ func walkrange(n *Node) *Node {
 		// This runs *after* the condition check, so we know
 		// advancing the pointer is safe and won't go past the
 		// end of the allocation.
-		tmp = nod(OADD, hp, nodintconst(t.Elem().Width))
-
-		tmp.Type = hp.Type
-		tmp.SetTypecheck(1)
-		tmp.Right.Type = types.Types[types.Tptr]
-		tmp.Right.SetTypecheck(1)
-		a = nod(OAS, hp, tmp)
+		a = nod(OAS, hp, addptr(hp, t.Elem().Width))
 		a = typecheck(a, Etop)
 		n.List.Set1(a)
 
@@ -613,3 +607,18 @@ func arrayClear(n, v1, v2, a *Node) bool {
 	n = walkstmt(n)
 	return true
 }
+
+// addptr returns (*T)(uintptr(p) + n).
+func addptr(p *Node, n int64) *Node {
+	t := p.Type
+
+	p = nod(OCONVNOP, p, nil)
+	p.Type = types.Types[TUINTPTR]
+
+	p = nod(OADD, p, nodintconst(n))
+
+	p = nod(OCONVNOP, p, nil)
+	p.Type = t
+
+	return p
+}

src/cmd/compile/internal/gc/ssa.go

@@ -1247,10 +1247,8 @@ var opToSSA = map[opAndType]ssa.Op{
 	opAndType{OADD, TUINT16}:  ssa.OpAdd16,
 	opAndType{OADD, TINT32}:   ssa.OpAdd32,
 	opAndType{OADD, TUINT32}:  ssa.OpAdd32,
-	opAndType{OADD, TPTR32}:   ssa.OpAdd32,
 	opAndType{OADD, TINT64}:   ssa.OpAdd64,
 	opAndType{OADD, TUINT64}:  ssa.OpAdd64,
-	opAndType{OADD, TPTR64}:   ssa.OpAdd64,
 	opAndType{OADD, TFLOAT32}: ssa.OpAdd32F,
 	opAndType{OADD, TFLOAT64}: ssa.OpAdd64F,