cmd/compile: change typecheck.iscmp into ir.Op.IsCmp

Change-Id: If89089cbd79b7ff030d856df3a7e6b7862c0f4ec
Reviewed-on: https://go-review.googlesource.com/c/go/+/345412
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>

src/cmd/compile/internal/ir/node.go

@@ -334,6 +334,16 @@ const (
 	OEND
 )
 
+// IsCmp reports whether op is a comparison operation (==, !=, <, <=,
+// >, or >=).
+func (op Op) IsCmp() bool {
+	switch op {
+	case OEQ, ONE, OLT, OLE, OGT, OGE:
+		return true
+	}
+	return false
+}
+
 // Nodes is a pointer to a slice of *Node.
 // For fields that are not used in most nodes, this is used instead of
 // a slice to save space.

src/cmd/compile/internal/noder/stencil.go

@@ -903,7 +903,7 @@ func (subst *subster) node(n ir.Node) ir.Node {
 		ir.EditChildren(m, edit)
 
 		m.SetTypecheck(1)
-		if typecheck.IsCmp(x.Op()) {
+		if x.Op().IsCmp() {
 			transformCompare(m.(*ir.BinaryExpr))
 		} else {
 			switch x.Op() {

src/cmd/compile/internal/typecheck/expr.go

@@ -77,10 +77,6 @@ func tcShift(n, l, r ir.Node) (ir.Node, ir.Node, *types.Type) {
 	return l, r, t
 }
 
-func IsCmp(op ir.Op) bool {
-	return iscmp[op]
-}
-
 // tcArith typechecks operands of a binary arithmetic expression.
 // The result of tcArith MUST be assigned back to original operands,
 // t is the type of the expression, and should be set by the caller. e.g:
@@ -96,7 +92,7 @@ func tcArith(n ir.Node, op ir.Op, l, r ir.Node) (ir.Node, ir.Node, *types.Type)
 		t = r.Type()
 	}
 	aop := ir.OXXX
-	if iscmp[n.Op()] && t.Kind() != types.TIDEAL && !types.Identical(l.Type(), r.Type()) {
+	if n.Op().IsCmp() && t.Kind() != types.TIDEAL && !types.Identical(l.Type(), r.Type()) {
 		// comparison is okay as long as one side is
 		// assignable to the other.  convert so they have
 		// the same type.

src/cmd/compile/internal/typecheck/universe.go

@@ -329,14 +329,6 @@ func InitUniverse() {
 	// special
 	okfor[ir.OCAP] = okforcap[:]
 	okfor[ir.OLEN] = okforlen[:]
-
-	// comparison
-	iscmp[ir.OLT] = true
-	iscmp[ir.OGT] = true
-	iscmp[ir.OGE] = true
-	iscmp[ir.OLE] = true
-	iscmp[ir.OEQ] = true
-	iscmp[ir.ONE] = true
 }
 
 func makeErrorInterface() *types.Type {