Hi Chris:
I am gopher from Beijing China . I am very like programing and adore
the old hack culture . and NBA too!
I am very happy in google groups and receive the answer so quickly.
go on practice programing and improve my badly english
question:
package main
func main() {
var a []int
Label1:
a = make([]int, 0, 2)
_ = a
}
could’t you give me an example that happens escape ?
在 2016年10月1日星期六 UTC+8上午12:19:17，Chris Manghane写道：
>
> Hmm, I'm not so sure if that's the rule. The rules are expressed in the
> code in
> https://github.com/golang/go/blob/master/src/cmd/compile/internal/gc/esc.go,
> which is unlikely to make any significant changes in the near future. Those
> rules aren't written in plain english, but we should not discourage any
> attempts to do so.
>
> Chris
>
> On Thu, Sep 29, 2016 at 11:42 PM, 'Axel Wagner' via golang-nuts <
> [email protected] <javascript:>> wrote:
>
>> The only real rule is "when the compiler can prove, that it doesn't
>> escape, it doesn't". There is no guarantee or fixed policy around escape
>> analysis.
>> If you are convinced that something doesn't escape and that the compiler
>> should be able to figure it out, you can try filing an issue about that
>> with the code and output of -gcflags=-m.
>>
>>
> On Fri, Sep 30, 2016 at 5:20 AM, 刘桂祥 <[email protected] <javascript:>>
>> wrote:
>>
>>> package main
>>>
>>> func main() {
>>> var m map[int]int
>>>
>>> {
>>> m = make(map[int]int)
>>> }
>>>
>>> _ = m
>>> }
>>>
>>> if I do this m will not escape just want to know what's the scope rule
>>> for escape ? puzzled
>>> <http://www.baidu.com/link?url=ApC817U9uUoCFHhS_dqb5JzUWJQsslUUA6_TDv3LDZBJgaA-G2ZbRfWA-2cGajgU_MHmTiXVEouMmdPN53mMMXxYd1nvCWWJJvfu5Mmg4Ca>
>>>
>>>
>>> 在 2016年9月29日星期四 UTC+8上午1:39:09，Chris Manghane写道：
>>>>
>>>> In the first example, make does not escape the scope of the for
>>>> statement. In the second example, make is assigned to m, which is outside
>>>> of the scope of the for statement, which means the make operation escapes
>>>> its scope and subsequently, is heap allocated. If you want more
>>>> information
>>>> about why something escapes, try compiling with -gcflags "-m -m" for an
>>>> explanation of the escape analysis information.
>>>>
>>>> On Wed, Sep 28, 2016 at 7:56 AM, 刘桂祥 <[email protected]> wrote:
>>>>
>>>>> go 1.7
>>>>>
>>>>> 在 2016年9月28日星期三 UTC+8下午10:41:09，Dave Cheney写道：
>>>>>
>>>>>> Which version of Go?
>>>>>>
>>>>>> On Thursday, 29 September 2016 00:18:29 UTC+10, 刘桂祥 wrote:
>>>>>>>
>>>>>>> // example1.go
>>>>>>> package main
>>>>>>>
>>>>>>>
>>>>>>> func main() {
>>>>>>>
>>>>>>> for i := 0; i < 2; i++ {
>>>>>>> m := make(map[int]int)
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> m[1] = 100
>>>>>>> }
>>>>>>>
>>>>>>>
>>>>>>> }
>>>>>>>
>>>>>>>
>>>>>>> main make(map[int]int) does not escape
>>>>>>>
>>>>>>>
>>>>>>> // example2.go
>>>>>>> package main
>>>>>>>
>>>>>>>
>>>>>>> func main() {
>>>>>>> var m map[int]int
>>>>>>> for i := 0; i < 2; i++ {
>>>>>>> m = make(map[int]int)
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> m[1] = 100
>>>>>>> }
>>>>>>>
>>>>>>>
>>>>>>> }
>>>>>>>
>>>>>>> make(map[int]int) escapes to heap why ???
>>>>>>>
>>>>>>>
>>>>>>> --
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>>>>>
>>>>
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