cmd/compile/internal/gc: remove stringsCompare

Inlined the last occurrence of stringsCompare into exprcmp.

Passes go build -a -toolexec 'toolstash -cmp' std cmd.

Change-Id: I8fd99e3fbffc84283cc269368595cba950533066
Reviewed-on: https://go-review.googlesource.com/14872
Reviewed-by: Dave Cheney <dave@cheney.net>
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -778,7 +778,13 @@ func exprcmp(c1, c2 *caseClause) int {
 		if len(a) > len(b) {
 			return +1
 		}
-		return stringsCompare(a, b)
+		if a == b {
+			return 0
+		}
+		if a < b {
+			return -1
+		}
+		return +1
 	}
 
 	return 0

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

@@ -0,0 +1,144 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gc
+
+import (
+	"cmd/compile/internal/big"
+	"testing"
+)
+
+func TestExprcmp(t *testing.T) {
+	testdata := []struct {
+		a, b caseClause
+		want int
+	}{
+		// Non-constants.
+		{
+			caseClause{node: Nod(OXXX, nil, nil), typ: caseKindExprVar},
+			caseClause{node: Nod(OXXX, nil, nil), typ: caseKindExprConst},
+			+1,
+		},
+		{
+			caseClause{node: Nod(OXXX, nil, nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nil, nil), typ: caseKindExprVar},
+			-1,
+		},
+		// Type switches
+		{
+			caseClause{node: Nod(OXXX, Nodintconst(0), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, Nodbool(true), nil), typ: caseKindExprConst},
+			-1,
+		},
+		{
+			caseClause{node: Nod(OXXX, Nodbool(true), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, Nodintconst(1), nil), typ: caseKindExprConst},
+			+1,
+		},
+		{
+			caseClause{node: Nod(OXXX, &Node{Type: &Type{Etype: TBOOL, Vargen: 1}}, nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, &Node{Type: &Type{Etype: TINT, Vargen: 0}}, nil), typ: caseKindExprConst},
+			+1,
+		},
+		{
+			caseClause{node: Nod(OXXX, &Node{Type: &Type{Etype: TBOOL, Vargen: 1}}, nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, &Node{Type: &Type{Etype: TINT, Vargen: 1}}, nil), typ: caseKindExprConst},
+			-1,
+		},
+		{
+			caseClause{node: Nod(OXXX, &Node{Type: &Type{Etype: TBOOL, Vargen: 0}}, nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, &Node{Type: &Type{Etype: TINT, Vargen: 1}}, nil), typ: caseKindExprConst},
+			-1,
+		},
+		// Constant values.
+		// CTFLT
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpflt{Val: *big.NewFloat(0.1)}}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpflt{Val: *big.NewFloat(0.2)}}), nil), typ: caseKindExprConst},
+			-1,
+		},
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpflt{Val: *big.NewFloat(0.1)}}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpflt{Val: *big.NewFloat(0.1)}}), nil), typ: caseKindExprConst},
+			0,
+		},
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpflt{Val: *big.NewFloat(0.2)}}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpflt{Val: *big.NewFloat(0.1)}}), nil), typ: caseKindExprConst},
+			+1,
+		},
+		// CTINT
+		{
+			caseClause{node: Nod(OXXX, Nodintconst(0), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, Nodintconst(1), nil), typ: caseKindExprConst},
+			-1,
+		},
+		{
+			caseClause{node: Nod(OXXX, Nodintconst(1), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, Nodintconst(1), nil), typ: caseKindExprConst},
+			0,
+		},
+		{
+			caseClause{node: Nod(OXXX, Nodintconst(1), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, Nodintconst(0), nil), typ: caseKindExprConst},
+			+1,
+		},
+		// CTRUNE
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpint{Val: *big.NewInt('a'), Rune: true}}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpint{Val: *big.NewInt('b'), Rune: true}}), nil), typ: caseKindExprConst},
+			-1,
+		},
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpint{Val: *big.NewInt('b'), Rune: true}}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpint{Val: *big.NewInt('b'), Rune: true}}), nil), typ: caseKindExprConst},
+			0,
+		},
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpint{Val: *big.NewInt('b'), Rune: true}}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{&Mpint{Val: *big.NewInt('a'), Rune: true}}), nil), typ: caseKindExprConst},
+			+1,
+		},
+		// CTSTR
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{"ab"}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{"abc"}), nil), typ: caseKindExprConst},
+			-1,
+		},
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{"abc"}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{"xyz"}), nil), typ: caseKindExprConst},
+			-1,
+		},
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{"abc"}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{"abc"}), nil), typ: caseKindExprConst},
+			0,
+		},
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{"abc"}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{"ab"}), nil), typ: caseKindExprConst},
+			+1,
+		},
+		{
+			caseClause{node: Nod(OXXX, nodlit(Val{"xyz"}), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodlit(Val{"abc"}), nil), typ: caseKindExprConst},
+			+1,
+		},
+		// Everything else should compare equal.
+		{
+			caseClause{node: Nod(OXXX, nodnil(), nil), typ: caseKindExprConst},
+			caseClause{node: Nod(OXXX, nodnil(), nil), typ: caseKindExprConst},
+			0,
+		},
+	}
+	for i, d := range testdata {
+		got := exprcmp(&d.a, &d.b)
+		if d.want != got {
+			t.Errorf("%d: exprcmp(a, b) = %d; want %d", i, got, d.want)
+			t.Logf("\ta = caseClause{node: %#v, typ: %#v}", d.a.node, d.a.typ)
+			t.Logf("\tb = caseClause{node: %#v, typ: %#v}", d.b.node, d.b.typ)
+		}
+	}
+}

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

@@ -17,17 +17,6 @@ func atoi(s string) int {
 	return int(n)
 }
 
-// strings.Compare, introduced in Go 1.5.
-func stringsCompare(a, b string) int {
-	if a == b {
-		return 0
-	}
-	if a < b {
-		return -1
-	}
-	return +1
-}
-
 var atExitFuncs []func()
 
 func AtExit(f func()) {