原文链接：分享如何浏览Go语言源码

前言

asongGo

Go源码包含哪些？

GoGoGosrc
GoGoGoGo

查看规范库源代码

UML
GDBdemofmt.Println

<img src=”https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/020ee5d660264362b42dab2a142bc369~tplv-k3u1fbpfcp-zoom-1.image” />

查看Go语言底层实现

GogoroutinemapGoGosrcruntimeGoruntimeGoGoGo

<img src=”https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/43155623d60042d98539d4885bb73020~tplv-k3u1fbpfcp-zoom-1.image” alt=”” />

剖析汇编代码

GoruntimeGoruntimeGoplan9x86plan9Goplan9makeslicedemo
// main.go
import "fmt"

func main() {
    s := make([]int, 10, 20)
    fmt.Println(s)
}

有两种形式能够查看汇编代码：

1. go tool compile -S -N -l main.go
2. go build main.go && go tool objdump ./main
.o

<img src=”https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/6071b1f1459144f5b891c3c4d60559df~tplv-k3u1fbpfcp-zoom-1.image” />

s := make([]int, 10, 20) runtime.makeslice(SB)runtimemakesliceruntime/slice.go

<img src=”https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/d9905faa0ef2479b997279691ddba98f~tplv-k3u1fbpfcp-zoom-1.image” />

在线调试

reviewGoGDBLLDBDelveDelveGoDelveGoDelveDelvedlvGonildlvdemo
import "fmt"

func main() {
    var s []int
    s = append(s, 1)
    fmt.Println(s)
}
dlv debug
$ dlv debug
Type 'help' for list of commands.
(dlv)
appendappend
(dlv) break main.go:7
Breakpoint 1 set at 0x10aba57 for main.main() ./main.go:7
continue
(dlv) continue
> main.main() ./main.go:7 (hits goroutine(1):1 total:1) (PC: 0x10aba57)
     2: 
     3: import "fmt"
     4: 
     5: func main() {
     6:         var s []int
=>   7:         s = append(s, 1)
     8:         fmt.Println(s)
     9: }
disassemblemain
(dlv) disassemble
TEXT main.main(SB) /Users/go/src/asong.cloud/Golang_Dream/code_demo/src_code/main.go
        main.go:5       0x10aba20       4c8d6424e8                      lea r12, ptr [rsp-0x18]
        main.go:5       0x10aba25       4d3b6610                        cmp r12, qword ptr [r14+0x10]
        main.go:5       0x10aba29       0f86f6000000                    jbe 0x10abb25
        main.go:5       0x10aba2f       4881ec98000000                  sub rsp, 0x98
        main.go:5       0x10aba36       4889ac2490000000                mov qword ptr [rsp+0x90], rbp
        main.go:5       0x10aba3e       488dac2490000000                lea rbp, ptr [rsp+0x90]
        main.go:6       0x10aba46       48c744246000000000              mov qword ptr [rsp+0x60], 0x0
        main.go:6       0x10aba4f       440f117c2468                    movups xmmword ptr [rsp+0x68], xmm15
        main.go:7       0x10aba55       eb00                            jmp 0x10aba57
=>      main.go:7       0x10aba57*      488d05a2740000                  lea rax, ptr [rip+0x74a2]
        main.go:7       0x10aba5e       31db                            xor ebx, ebx
        main.go:7       0x10aba60       31c9                            xor ecx, ecx
        main.go:7       0x10aba62       4889cf                          mov rdi, rcx
        main.go:7       0x10aba65       be01000000                      mov esi, 0x1
        main.go:7       0x10aba6a       e871c3f9ff                      call $runtime.growslice
        main.go:7       0x10aba6f       488d5301                        lea rdx, ptr [rbx+0x1]
        main.go:7       0x10aba73       eb00                            jmp 0x10aba75
        main.go:7       0x10aba75       48c70001000000                  mov qword ptr [rax], 0x1
        main.go:7       0x10aba7c       4889442460                      mov qword ptr [rsp+0x60], rax
        main.go:7       0x10aba81       4889542468                      mov qword ptr [rsp+0x68], rdx
        main.go:7       0x10aba86       48894c2470                      mov qword ptr [rsp+0x70], rcx
        main.go:8       0x10aba8b       440f117c2450                    movups xmmword ptr [rsp+0x50], xmm15
        main.go:8       0x10aba91       488d542450                      lea rdx, ptr [rsp+0x50]
        main.go:8       0x10aba96       4889542448                      mov qword ptr [rsp+0x48], rdx
        main.go:8       0x10aba9b       488b442460                      mov rax, qword ptr [rsp+0x60]
        main.go:8       0x10abaa0       488b5c2468                      mov rbx, qword ptr [rsp+0x68]
        main.go:8       0x10abaa5       488b4c2470                      mov rcx, qword ptr [rsp+0x70]
        main.go:8       0x10abaaa       e8f1dff5ff                      call $runtime.convTslice
        main.go:8       0x10abaaf       4889442440                      mov qword ptr [rsp+0x40], rax
        main.go:8       0x10abab4       488b542448                      mov rdx, qword ptr [rsp+0x48]
        main.go:8       0x10abab9       8402                            test byte ptr [rdx], al
        main.go:8       0x10ababb       488d35be640000                  lea rsi, ptr [rip+0x64be]
        main.go:8       0x10abac2       488932                          mov qword ptr [rdx], rsi
        main.go:8       0x10abac5       488d7a08                        lea rdi, ptr [rdx+0x8]
        main.go:8       0x10abac9       833d30540d0000                  cmp dword ptr [runtime.writeBarrier], 0x0
        main.go:8       0x10abad0       7402                            jz 0x10abad4
        main.go:8       0x10abad2       eb06                            jmp 0x10abada
        main.go:8       0x10abad4       48894208                        mov qword ptr [rdx+0x8], rax
        main.go:8       0x10abad8       eb08                            jmp 0x10abae2
        main.go:8       0x10abada       e8213ffbff                      call $runtime.gcWriteBarrier
        main.go:8       0x10abadf       90                              nop
        main.go:8       0x10abae0       eb00                            jmp 0x10abae2
        main.go:8       0x10abae2       488b442448                      mov rax, qword ptr [rsp+0x48]
        main.go:8       0x10abae7       8400                            test byte ptr [rax], al
        main.go:8       0x10abae9       eb00                            jmp 0x10abaeb
        main.go:8       0x10abaeb       4889442478                      mov qword ptr [rsp+0x78], rax
        main.go:8       0x10abaf0       48c784248000000001000000        mov qword ptr [rsp+0x80], 0x1
        main.go:8       0x10abafc       48c784248800000001000000        mov qword ptr [rsp+0x88], 0x1
        main.go:8       0x10abb08       bb01000000                      mov ebx, 0x1
        main.go:8       0x10abb0d       4889d9                          mov rcx, rbx
        main.go:8       0x10abb10       e8aba8ffff                      call $fmt.Println
        main.go:9       0x10abb15       488bac2490000000                mov rbp, qword ptr [rsp+0x90]
        main.go:9       0x10abb1d       4881c498000000                  add rsp, 0x98
        main.go:9       0x10abb24       c3                              ret
        main.go:5       0x10abb25       e8f61efbff                      call $runtime.morestack_noctxt
        .:0             0x10abb2a       e9f1feffff                      jmp $main.main
runtime.growslice
(dlv) break runtime.growslice
Breakpoint 2 set at 0x1047dea for runtime.growslice() /usr/local/opt/go/libexec/src/runtime/slice.go:162
continue
(dlv) continue
> runtime.growslice() /usr/local/opt/go/libexec/src/runtime/slice.go:162 (hits goroutine(1):1 total:1) (PC: 0x1047dea)
Warning: debugging optimized function
   157: // NOT to the new requested capacity.
   158: // This is for codegen convenience. The old slice's length is used immediately
   159: // to calculate where to write new values during an append.
   160: // TODO: When the old backend is gone, reconsider this decision.
   161: // The SSA backend might prefer the new length or to return only ptr/cap and save stack space.
=> 162: func growslice(et *_type, old slice, cap int) slice {
   163:         if raceenabled {
   164:                 callerpc := getcallerpc()
   165:                 racereadrangepc(old.array, uintptr(old.len*int(et.size)), callerpc, funcPC(growslice))
   166:         }
   167:         if msanenabled {
nilgrowslice

上文咱们介绍调试汇编的一个根本流程，上面在介绍两个我在看源代码时常常应用的命令；

goroutinesgoroutinegoroutine (alias: gr)gourtine
(dlv) grs
* Goroutine 1 - User: ./main.go:7 main.main (0x10aba6f) (thread 218565)
  Goroutine 2 - User: /usr/local/opt/go/libexec/src/runtime/proc.go:367 runtime.gopark (0x1035232) [force gc (idle)]
  Goroutine 3 - User: /usr/local/opt/go/libexec/src/runtime/proc.go:367 runtime.gopark (0x1035232) [GC sweep wait]
  Goroutine 4 - User: /usr/local/opt/go/libexec/src/runtime/proc.go:367 runtime.gopark (0x1035232) [GC scavenge wait]
  Goroutine 5 - User: /usr/local/opt/go/libexec/src/runtime/proc.go:367 runtime.gopark (0x1035232) [finalizer wait]
stackstack
(dlv) bt
0  0x0000000001047e15 in runtime.growslice
   at /usr/local/opt/go/libexec/src/runtime/slice.go:183
1  0x00000000010aba6f in main.main
   at ./main.go:7
2  0x0000000001034e13 in runtime.main
   at /usr/local/opt/go/libexec/src/runtime/proc.go:255
3  0x000000000105f9c1 in runtime.goexit
   at /usr/local/opt/go/libexec/src/runtime/asm_amd64.s:1581
regsregs
(dlv) regs
   Rip = 0x0000000001047e15
   Rsp = 0x000000c00010de68
   Rax = 0x00000000010b2f00
   Rbx = 0x0000000000000000
   Rcx = 0x0000000000000000
   Rdx = 0x0000000000000008
   Rsi = 0x0000000000000001
   Rdi = 0x0000000000000000
   Rbp = 0x000000c00010ded0
    R8 = 0x0000000000000000
    R9 = 0x0000000000000008
   R10 = 0x0000000001088c40
   R11 = 0x0000000000000246
   R12 = 0x000000c00010df60
   R13 = 0x0000000000000000
   R14 = 0x000000c0000001a0
   R15 = 0x00000000000000c8
Rflags = 0x0000000000000202     [IF IOPL=0]
    Cs = 0x000000000000002b
    Fs = 0x0000000000000000
    Gs = 0x0000000000000000
localslocals
(dlv) locals
newcap = 1
doublecap = 0

总结

看源代码的过程是没有捷径可走的，如果说有，那就是能够先看一些大佬输入的底层原理的文章，而后参照其文章一步步入门源码浏览，最终还是要本人去克服这个艰难，本文介绍了我本人查看源码的一些形式，你是否有更简便的形式呢？欢送评论区分享进去～。

好啦，本文到这里就完结了，我是asong，咱们下期见。

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