1// Copyright 2016 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// This test makes sure that we don't split a single 6// load up into two separate loads. 7 8package main 9 10import "testing" 11 12//go:noinline 13func read1(b []byte) (uint16, uint16) { 14 // There is only a single read of b[0]. The two 15 // returned values must have the same low byte. 16 v := b[0] 17 return uint16(v), uint16(v) | uint16(b[1])<<8 18} 19 20func main1(t *testing.T) { 21 const N = 100000 22 done := make(chan bool, 2) 23 b := make([]byte, 2) 24 go func() { 25 for i := 0; i < N; i++ { 26 b[0] = byte(i) 27 b[1] = byte(i) 28 } 29 done <- true 30 }() 31 go func() { 32 for i := 0; i < N; i++ { 33 x, y := read1(b) 34 if byte(x) != byte(y) { 35 t.Errorf("x=%x y=%x\n", x, y) 36 done <- false 37 return 38 } 39 } 40 done <- true 41 }() 42 <-done 43 <-done 44} 45 46//go:noinline 47func read2(b []byte) (uint16, uint16) { 48 // There is only a single read of b[1]. The two 49 // returned values must have the same high byte. 50 v := uint16(b[1]) << 8 51 return v, uint16(b[0]) | v 52} 53 54func main2(t *testing.T) { 55 const N = 100000 56 done := make(chan bool, 2) 57 b := make([]byte, 2) 58 go func() { 59 for i := 0; i < N; i++ { 60 b[0] = byte(i) 61 b[1] = byte(i) 62 } 63 done <- true 64 }() 65 go func() { 66 for i := 0; i < N; i++ { 67 x, y := read2(b) 68 if x&0xff00 != y&0xff00 { 69 t.Errorf("x=%x y=%x\n", x, y) 70 done <- false 71 return 72 } 73 } 74 done <- true 75 }() 76 <-done 77 <-done 78} 79 80func TestDupLoad(t *testing.T) { 81 main1(t) 82 main2(t) 83} 84