一个栈上变量会地址会更改的例子

[widon1104]

package main

var b *int

func main() {
	testStack()
}

func testStack() {
	var x int = 1
	//b = &x
	println(&x)
	testLargeX(&x)
	println(&x)
}

func testLargeX(x *int) {
	var a = make([]int, 2000)
	for i := 0; i < len(a); i++ {
		a[i] = 1
	}
	println(a[1])
	println(x, *x)
}

这个程序输出为：
0xc000042770
1
0xc000107f70 1
0xc000107f70
x这个栈上变量因为栈空间的扩张，栈在另一个地方重新分配内存，x的地址变化了

如果把注释的那行 b = &x放开
widon@widon-deepin:~/golang/src/test/stackTest$ go build -gcflags="-m"
test/stackTest
./1.go:9:6: can inline testStack
./1.go:5:6: can inline main
./1.go:6:11: inlining call to testStack
./1.go:17:17: x does not escape
./1.go:18:14: make([]int, 2000) does not escape
./1.go:6:11: moved to heap: x
./1.go:10:6: moved to heap: x
x就会在堆上分配内存，那x的地址就不会变化了

[cch123]

这个例子挺不错的

[lesismal]

go build -gcflags="-m"

请问这个例子用的golang是什么什么版本？我这里得到的结果不太一样，1.14还是哪个版本之后，默认栈是8k了，我1.16试了下，2000字节到7k，指针打印的值都没变，改成8k，栈不够了，也是变量a（var a = make([]int, 1024*8）逃逸了、栈和栈变量地址没有改变：

0xc00003df68
1
0xc00003df68 1
0xc00003df68

7k内联逃逸情况：

go build -gcflags="-m" .\stack.go
# command-line-arguments
.\stack.go:17:6: can inline testLargeX
.\stack.go:9:6: can inline testStack
.\stack.go:13:12: inlining call to testLargeX
.\stack.go:5:6: can inline main
.\stack.go:6:11: inlining call to testStack
.\stack.go:6:11: inlining call to testLargeX
.\stack.go:6:11: make([]int, 1024 * 7) does not escape
.\stack.go:13:12: make([]int, 1024 * 7) does not escape
.\stack.go:17:17: x does not escape
.\stack.go:18:14: make([]int, 1024 * 7) does not escape

8k内联逃逸情况：

go build -gcflags="-m" .\stack.go
# command-line-arguments
.\stack.go:17:6: can inline testLargeX
.\stack.go:9:6: can inline testStack
.\stack.go:13:12: inlining call to testLargeX
.\stack.go:5:6: can inline main
.\stack.go:6:11: inlining call to testStack
.\stack.go:6:11: inlining call to testLargeX
.\stack.go:6:11: make([]int, 1024 * 8) escapes to heap
.\stack.go:13:12: make([]int, 1024 * 8) escapes to heap
.\stack.go:17:17: x does not escape
.\stack.go:18:14: make([]int, 1024 * 8) escapes to heap

而且单就楼主例子中的 make([]byte, 2000)，go历史版本最小栈也有2048吧、但是得是非常老的版本了吧？而且即使老版本因为这2000而导致栈扩容，但是栈变量地址改变还需要栈扩容时原栈尾部没有空闲内存可用realloc才会触发，这个简单的例子想触发，应该得是比较特殊得环境才行吧？