test/codegen: port 2^n muls tests to codegen harness

And delete them from the asm_test.go file.

Change-Id: I124c8c352299646ec7db0968cdb0fe59a3b5d83d
Reviewed-on: https://go-review.googlesource.com/99475
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Giovanni Bajo <rasky@develer.com>

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

@@ -272,26 +272,6 @@ var allAsmTests = []*asmTests{
 }
 
 var linuxAMD64Tests = []*asmTest{
-	// multiplication by powers of two
-	{
-		fn: `
-		func $(n int) int {
-			return n * 64
-		}
-		`,
-		pos: []string{"\tSHLQ\t\\$6,"},
-		neg: []string{"IMULQ"},
-	},
-	{
-		fn: `
-		func $(n int) int {
-			return -128*n
-		}
-		`,
-		pos: []string{"SHLQ"},
-		neg: []string{"IMULQ"},
-	},
-
 	{
 		fn: `
 		func $(x int) int {
@@ -927,26 +907,6 @@ var linuxAMD64Tests = []*asmTest{
 }
 
 var linux386Tests = []*asmTest{
-	// multiplication by powers of two
-	{
-		fn: `
-		func $(n int) int {
-			return 32*n
-		}
-		`,
-		pos: []string{"SHLL"},
-		neg: []string{"IMULL"},
-	},
-	{
-		fn: `
-		func $(n int) int {
-			return -64*n
-		}
-		`,
-		pos: []string{"SHLL"},
-		neg: []string{"IMULL"},
-	},
-
 	// multiplication merging tests
 	{
 		fn: `
@@ -1155,26 +1115,6 @@ var linuxS390XTests = []*asmTest{
 }
 
 var linuxARMTests = []*asmTest{
-	// multiplication by powers of two
-	{
-		fn: `
-		func $(n int) int {
-			return 16*n
-		}
-		`,
-		pos: []string{"\tSLL\t[$]4"},
-		neg: []string{"\tMUL\t"},
-	},
-	{
-		fn: `
-		func $(n int) int {
-			return -32*n
-		}
-		`,
-		pos: []string{"\tSLL\t[$]5"},
-		neg: []string{"\tMUL\t"},
-	},
-
 	{
 		fn: `
 		func f0(x uint32) uint32 {
@@ -1222,26 +1162,6 @@ var linuxARMTests = []*asmTest{
 }
 
 var linuxARM64Tests = []*asmTest{
-	// multiplication by powers of two
-	{
-		fn: `
-		func $(n int) int {
-			return 64*n
-		}
-		`,
-		pos: []string{"\tLSL\t[$]6"},
-		neg: []string{"\tMUL\t"},
-	},
-	{
-		fn: `
-		func $(n int) int {
-			return -128*n
-		}
-		`,
-		pos: []string{"\tLSL\t[$]7"},
-		neg: []string{"\tMUL\t"},
-	},
-
 	{
 		fn: `
 		func f0(x uint64) uint64 {

test/codegen/arithmetic.go

+// asmcheck
+
+// Copyright 2018 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 codegen
+
+// This file contains codegen tests related to arithmetic
+// simplifications/optimizations.
+
+func Pow2Muls(n1, n2 int) (int, int) {
+	// amd64:"SHLQ\t[$]5",-"IMULQ"
+	// 386:"SHLL\t[$]5",-"IMULL"
+	// arm:"SLL\t[$]5",-"MUL"
+	// arm64:"LSL\t[$]5",-"MUL"
+	a := n1 * 32
+
+	// amd64:"SHLQ\t[$]6",-"IMULQ"
+	// 386:"SHLL\t[$]6",-"IMULL"
+	// arm:"SLL\t[$]6",-"MUL"
+	// arm64:"LSL\t[$]6",-"MUL"
+	b := -64 * n2
+
+	return a, b
+}