defer 具名 匿名 汇编 objdump
func increaseA() int {
var i int
defer func() {
i += 256
}()
return i
}
func increaseB() (r int) {
defer func() {
r += 256
}()
return r
}
func increaseA() int {
var i int
defer func() {
i += 0x1234
}()
return i
}
func increaseB() (r int) {
defer func() {
r += 0x1234
}()
return r
}
func main() {
i := increaseA()
j := increaseB()
if i != 0 {
panic(i)
}
if j != 0x1234 {
panic(j)
}
}
package main
import "fmt"
func fDefer(i int) int {
defer func() {
i += 6789 // 0x1a85
}()
defer func() {
i += 5678 // 0x162e
}()
i += 1234 // 0x4d2
i += 2345 // 0x929
// 3579 0xdfb
return i
}
func main() {
i := fDefer(16) // 3595 0xe0b
fmt.Print(i)
}
go tool compile -S main.go > tmp2
main.fDefer STEXT size=239 args=0x8 locals=0x48 funcid=0x0 align=0x0 0x0000 00000 (main.go:3) TEXT main.fDefer(SB), ABIInternal, $72-8 0x0000 00000 (main.go:3) CMPQ SP, 16(R14) 0x0004 00004 (main.go:3) PCDATA $0, $-2 0x0004 00004 (main.go:3) JLS 216 0x000a 00010 (main.go:3) PCDATA $0, $-1 0x000a 00010 (main.go:3) SUBQ $72, SP 0x000e 00014 (main.go:3) MOVQ BP, 64(SP) 0x0013 00019 (main.go:3) LEAQ 64(SP), BP 0x0018 00024 (main.go:3) MOVUPS X15, 48(SP) 0x001e 00030 (main.go:3) FUNCDATA $0, gclocals·J5F+7Qw7O7ve2QcWC7DpeQ==(SB) 0x001e 00030 (main.go:3) FUNCDATA $1, gclocals·ySXA9Y8PBdcDMJxYV/AD1w==(SB) 0x001e 00030 (main.go:3) FUNCDATA $2, main.fDefer.stkobj(SB) 0x001e 00030 (main.go:3) FUNCDATA $5, main.fDefer.arginfo1(SB) 0x001e 00030 (main.go:3) FUNCDATA $4, main.fDefer.opendefer(SB) 0x001e 00030 (main.go:3) MOVB $0, main..autotmp_6+7(SP) 0x0023 00035 (main.go:3) MOVQ AX, main.i+80(SP) 0x0028 00040 (main.go:3) MOVQ $0, main.~r0+8(SP) 0x0031 00049 (main.go:4) MOVUPS X15, main..autotmp_3+32(SP) 0x0037 00055 (main.go:4) LEAQ main.fDefer.func1(SB), AX 0x003e 00062 (main.go:4) MOVQ AX, main..autotmp_3+32(SP) 0x0043 00067 (main.go:4) LEAQ main.i+80(SP), AX 0x0048 00072 (main.go:4) MOVQ AX, main..autotmp_3+40(SP) 0x004d 00077 (main.go:4) LEAQ main..autotmp_3+32(SP), CX 0x0052 00082 (main.go:4) MOVQ CX, main..autotmp_7+56(SP) 0x0057 00087 (main.go:4) MOVB $1, main..autotmp_6+7(SP) 0x005c 00092 (main.go:7) MOVUPS X15, main..autotmp_5+16(SP) 0x0062 00098 (main.go:7) LEAQ main.fDefer.func2(SB), CX 0x0069 00105 (main.go:7) MOVQ CX, main..autotmp_5+16(SP) 0x006e 00110 (main.go:7) MOVQ AX, main..autotmp_5+24(SP) 0x0073 00115 (main.go:7) LEAQ main..autotmp_5+16(SP), AX 0x0078 00120 (main.go:7) MOVQ AX, main..autotmp_8+48(SP) 0x007d 00125 (main.go:7) MOVB $3, main..autotmp_6+7(SP) 0x0082 00130 (main.go:10) MOVQ main.i+80(SP), AX 0x0087 00135 (main.go:11) ADDQ $3579, AX 0x008d 00141 (main.go:11) MOVQ AX, main.i+80(SP) 0x0092 00146 (main.go:13) MOVQ AX, main.~r0+8(SP) 0x0097 00151 (main.go:13) MOVB $1, main..autotmp_6+7(SP) 0x009c 00156 (main.go:13) MOVQ main..autotmp_8+48(SP), DX 0x00a1 00161 (main.go:13) MOVQ (DX), AX 0x00a4 00164 (main.go:13) PCDATA $1, $1 0x00a4 00164 (main.go:13) CALL AX 0x00a6 00166 (main.go:13) MOVB $0, main..autotmp_6+7(SP) 0x00ab 00171 (main.go:13) MOVQ main..autotmp_7+56(SP), DX 0x00b0 00176 (main.go:13) MOVQ (DX), AX 0x00b3 00179 (main.go:13) CALL AX 0x00b5 00181 (main.go:13) MOVQ main.~r0+8(SP), AX 0x00ba 00186 (main.go:13) MOVQ 64(SP), BP 0x00bf 00191 (main.go:13) ADDQ $72, SP 0x00c3 00195 (main.go:13) RET 0x00c4 00196 (main.go:13) CALL runtime.deferreturn(SB) 0x00c9 00201 (main.go:13) MOVQ main.~r0+8(SP), AX 0x00ce 00206 (main.go:13) MOVQ 64(SP), BP 0x00d3 00211 (main.go:13) ADDQ $72, SP 0x00d7 00215 (main.go:13) RET 0x00d8 00216 (main.go:13) NOP 0x00d8 00216 (main.go:3) PCDATA $1, $-1 0x00d8 00216 (main.go:3) PCDATA $0, $-2 0x00d8 00216 (main.go:3) MOVQ AX, 8(SP) 0x00dd 00221 (main.go:3) NOP 0x00e0 00224 (main.go:3) CALL runtime.morestack_noctxt(SB) 0x00e5 00229 (main.go:3) MOVQ 8(SP), AX 0x00ea 00234 (main.go:3) PCDATA $0, $-1 0x00ea 00234 (main.go:3) JMP 0 0x0000 49 3b 66 10 0f 86 ce 00 00 00 48 83 ec 48 48 89 I;f.......H..HH. 0x0010 6c 24 40 48 8d 6c 24 40 44 0f 11 7c 24 30 c6 44 l$@H.l$@D..|$0.D 0x0020 24 07 00 48 89 44 24 50 48 c7 44 24 08 00 00 00 $..H.D$PH.D$.... 0x0030 00 44 0f 11 7c 24 20 48 8d 05 00 00 00 00 48 89 .D..|$ H......H. 0x0040 44 24 20 48 8d 44 24 50 48 89 44 24 28 48 8d 4c D$ H.D$PH.D$(H.L 0x0050 24 20 48 89 4c 24 38 c6 44 24 07 01 44 0f 11 7c $ H.L$8.D$..D..| 0x0060 24 10 48 8d 0d 00 00 00 00 48 89 4c 24 10 48 89 $.H......H.L$.H. 0x0070 44 24 18 48 8d 44 24 10 48 89 44 24 30 c6 44 24 D$.H.D$.H.D$0.D$ 0x0080 07 03 48 8b 44 24 50 48 05 fb 0d 00 00 48 89 44 ..H.D$PH.....H.D 0x0090 24 50 48 89 44 24 08 c6 44 24 07 01 48 8b 54 24 $PH.D$..D$..H.T$ 0x00a0 30 48 8b 02 ff d0 c6 44 24 07 00 48 8b 54 24 38 0H.....D$..H.T$8 0x00b0 48 8b 02 ff d0 48 8b 44 24 08 48 8b 6c 24 40 48 H....H.D$.H.l$@H 0x00c0 83 c4 48 c3 e8 00 00 00 00 48 8b 44 24 08 48 8b ..H......H.D$.H. 0x00d0 6c 24 40 48 83 c4 48 c3 48 89 44 24 08 0f 1f 00 l$@H..H.H.D$.... 0x00e0 e8 00 00 00 00 48 8b 44 24 08 e9 11 ff ff ff .....H.D$...... rel 58+4 t=14 main.fDefer.func1+0 rel 101+4 t=14 main.fDefer.func2+0 rel 164+0 t=10 +0 rel 179+0 t=10 +0 rel 197+4 t=7 runtime.deferreturn+0 rel 225+4 t=7 runtime.morestack_noctxt+0 main.fDefer.func2 STEXT nosplit size=12 args=0x0 locals=0x0 funcid=0x0 align=0x0 0x0000 00000 (main.go:7) TEXT main.fDefer.func2(SB), NOSPLIT|NEEDCTXT|ABIInternal, $0-0 0x0000 00000 (main.go:7) FUNCDATA $0, gclocals·g2BeySu+wFnoycgXfElmcg==(SB) 0x0000 00000 (main.go:7) FUNCDATA $1, gclocals·g2BeySu+wFnoycgXfElmcg==(SB) 0x0000 00000 (main.go:7) MOVQ 8(DX), AX 0x0004 00004 (main.go:8) ADDQ $5678, (AX) 0x000b 00011 (main.go:9) RET 0x0000 48 8b 42 08 48 81 00 2e 16 00 00 c3 H.B.H....... main.fDefer.func1 STEXT nosplit size=12 args=0x0 locals=0x0 funcid=0x0 align=0x0 0x0000 00000 (main.go:4) TEXT main.fDefer.func1(SB), NOSPLIT|NEEDCTXT|ABIInternal, $0-0 0x0000 00000 (main.go:4) FUNCDATA $0, gclocals·g2BeySu+wFnoycgXfElmcg==(SB) 0x0000 00000 (main.go:4) FUNCDATA $1, gclocals·g2BeySu+wFnoycgXfElmcg==(SB) 0x0000 00000 (main.go:4) MOVQ 8(DX), AX 0x0004 00004 (main.go:5) ADDQ $6789, (AX) 0x000b 00011 (main.go:6) RET 0x0000 48 8b 42 08 48 81 00 85 1a 00 00 c3 H.B.H....... main.main STEXT size=78 args=0x0 locals=0x18 funcid=0x0 align=0x0 0x0000 00000 (main.go:15) TEXT main.main(SB), ABIInternal, $24-0 0x0000 00000 (main.go:15) CMPQ SP, 16(R14) 0x0004 00004 (main.go:15) PCDATA $0, $-2 0x0004 00004 (main.go:15) JLS 71 0x0006 00006 (main.go:15) PCDATA $0, $-1 0x0006 00006 (main.go:15) SUBQ $24, SP 0x000a 00010 (main.go:15) MOVQ BP, 16(SP) 0x000f 00015 (main.go:15) LEAQ 16(SP), BP 0x0014 00020 (main.go:15) FUNCDATA $0, gclocals·g2BeySu+wFnoycgXfElmcg==(SB) 0x0014 00020 (main.go:15) FUNCDATA $1, gclocals·g2BeySu+wFnoycgXfElmcg==(SB) 0x0014 00020 (main.go:16) MOVL $16, AX 0x0019 00025 (main.go:16) PCDATA $1, $0 0x0019 00025 (main.go:16) CALL main.fDefer(SB) 0x001e 00030 (main.go:16) NOP 0x0020 00032 (main.go:17) CMPQ AX, $3595 0x0026 00038 (main.go:17) JNE 50 0x0028 00040 (main.go:20) PCDATA $1, $-1 0x0028 00040 (main.go:20) MOVQ 16(SP), BP 0x002d 00045 (main.go:20) ADDQ $24, SP 0x0031 00049 (main.go:20) RET 0x0032 00050 (main.go:18) PCDATA $1, $0 0x0032 00050 (main.go:18) CALL runtime.convT64(SB) 0x0037 00055 (main.go:18) MOVQ AX, BX 0x003a 00058 (main.go:18) LEAQ type.int(SB), AX 0x0041 00065 (main.go:18) CALL runtime.gopanic(SB) 0x0046 00070 (main.go:18) XCHGL AX, AX 0x0047 00071 (main.go:18) NOP 0x0047 00071 (main.go:15) PCDATA $1, $-1 0x0047 00071 (main.go:15) PCDATA $0, $-2 0x0047 00071 (main.go:15) CALL runtime.morestack_noctxt(SB) 0x004c 00076 (main.go:15) PCDATA $0, $-1 0x004c 00076 (main.go:15) JMP 0 0x0000 49 3b 66 10 76 41 48 83 ec 18 48 89 6c 24 10 48 I;f.vAH...H.l$.H 0x0010 8d 6c 24 10 b8 10 00 00 00 e8 00 00 00 00 66 90 .l$...........f. 0x0020 48 3d 0b 0e 00 00 75 0a 48 8b 6c 24 10 48 83 c4 H=....u.H.l$.H.. 0x0030 18 c3 e8 00 00 00 00 48 89 c3 48 8d 05 00 00 00 .......H..H..... 0x0040 00 e8 00 00 00 00 90 e8 00 00 00 00 eb b2 .............. rel 2+0 t=23 type.int+0 rel 26+4 t=7 main.fDefer+0 rel 51+4 t=7 runtime.convT64+0 rel 61+4 t=14 type.int+0 rel 66+4 t=7 runtime.gopanic+0 rel 72+4 t=7 runtime.morestack_noctxt+0
go build -o a;./a;objdump -d a > tmp1
0000000000457c80 <main.fDefer>: 457c80: 49 3b 66 10 cmp 0x10(%r14),%rsp 457c84: 0f 86 ce 00 00 00 jbe 457d58 <main.fDefer+0xd8> 457c8a: 48 83 ec 48 sub $0x48,%rsp 457c8e: 48 89 6c 24 40 mov %rbp,0x40(%rsp) 457c93: 48 8d 6c 24 40 lea 0x40(%rsp),%rbp 457c98: 44 0f 11 7c 24 30 movups %xmm15,0x30(%rsp) 457c9e: c6 44 24 07 00 movb $0x0,0x7(%rsp) 457ca3: 48 89 44 24 50 mov %rax,0x50(%rsp) 457ca8: 48 c7 44 24 08 00 00 movq $0x0,0x8(%rsp) 457caf: 00 00 457cb1: 44 0f 11 7c 24 20 movups %xmm15,0x20(%rsp) 457cb7: 48 8d 05 e2 00 00 00 lea 0xe2(%rip),%rax # 457da0 <main.fDefer.func1> 457cbe: 48 89 44 24 20 mov %rax,0x20(%rsp) 457cc3: 48 8d 44 24 50 lea 0x50(%rsp),%rax 457cc8: 48 89 44 24 28 mov %rax,0x28(%rsp) 457ccd: 48 8d 4c 24 20 lea 0x20(%rsp),%rcx 457cd2: 48 89 4c 24 38 mov %rcx,0x38(%rsp) 457cd7: c6 44 24 07 01 movb $0x1,0x7(%rsp) 457cdc: 44 0f 11 7c 24 10 movups %xmm15,0x10(%rsp) 457ce2: 48 8d 0d 97 00 00 00 lea 0x97(%rip),%rcx # 457d80 <main.fDefer.func2> 457ce9: 48 89 4c 24 10 mov %rcx,0x10(%rsp) 457cee: 48 89 44 24 18 mov %rax,0x18(%rsp) 457cf3: 48 8d 44 24 10 lea 0x10(%rsp),%rax 457cf8: 48 89 44 24 30 mov %rax,0x30(%rsp) 457cfd: c6 44 24 07 03 movb $0x3,0x7(%rsp) 457d02: 48 8b 44 24 50 mov 0x50(%rsp),%rax 457d07: 48 05 fb 0d 00 00 add $0xdfb,%rax 457d0d: 48 89 44 24 50 mov %rax,0x50(%rsp) 457d12: 48 89 44 24 08 mov %rax,0x8(%rsp) 457d17: c6 44 24 07 01 movb $0x1,0x7(%rsp) 457d1c: 48 8b 54 24 30 mov 0x30(%rsp),%rdx 457d21: 48 8b 02 mov (%rdx),%rax 457d24: ff d0 call *%rax 457d26: c6 44 24 07 00 movb $0x0,0x7(%rsp) 457d2b: 48 8b 54 24 38 mov 0x38(%rsp),%rdx 457d30: 48 8b 02 mov (%rdx),%rax 457d33: ff d0 call *%rax 457d35: 48 8b 44 24 08 mov 0x8(%rsp),%rax 457d3a: 48 8b 6c 24 40 mov 0x40(%rsp),%rbp 457d3f: 48 83 c4 48 add $0x48,%rsp 457d43: c3 ret 457d44: e8 f7 47 fd ff call 42c540 <runtime.deferreturn> 457d49: 48 8b 44 24 08 mov 0x8(%rsp),%rax 457d4e: 48 8b 6c 24 40 mov 0x40(%rsp),%rbp 457d53: 48 83 c4 48 add $0x48,%rsp 457d57: c3 ret 457d58: 48 89 44 24 08 mov %rax,0x8(%rsp) 457d5d: 0f 1f 00 nopl (%rax) 457d60: e8 5b cc ff ff call 4549c0 <runtime.morestack_noctxt.abi0> 457d65: 48 8b 44 24 08 mov 0x8(%rsp),%rax 457d6a: e9 11 ff ff ff jmp 457c80 <main.fDefer> 457d6f: cc int3 457d70: cc int3 457d71: cc int3 457d72: cc int3 457d73: cc int3 457d74: cc int3 457d75: cc int3 457d76: cc int3 457d77: cc int3 457d78: cc int3 457d79: cc int3 457d7a: cc int3 457d7b: cc int3 457d7c: cc int3 457d7d: cc int3 457d7e: cc int3 457d7f: cc int3 0000000000457d80 <main.fDefer.func2>: 457d80: 48 8b 42 08 mov 0x8(%rdx),%rax 457d84: 48 81 00 2e 16 00 00 addq $0x162e,(%rax) 457d8b: c3 ret 457d8c: cc int3 457d8d: cc int3 457d8e: cc int3 457d8f: cc int3 457d90: cc int3 457d91: cc int3 457d92: cc int3 457d93: cc int3 457d94: cc int3 457d95: cc int3 457d96: cc int3 457d97: cc int3 457d98: cc int3 457d99: cc int3 457d9a: cc int3 457d9b: cc int3 457d9c: cc int3 457d9d: cc int3 457d9e: cc int3 457d9f: cc int3 0000000000457da0 <main.fDefer.func1>: 457da0: 48 8b 42 08 mov 0x8(%rdx),%rax 457da4: 48 81 00 85 1a 00 00 addq $0x1a85,(%rax) 457dab: c3 ret 457dac: cc int3 457dad: cc int3 457dae: cc int3 457daf: cc int3 457db0: cc int3 457db1: cc int3 457db2: cc int3 457db3: cc int3 457db4: cc int3 457db5: cc int3 457db6: cc int3 457db7: cc int3 457db8: cc int3 457db9: cc int3 457dba: cc int3 457dbb: cc int3 457dbc: cc int3 457dbd: cc int3 457dbe: cc int3 457dbf: cc int3 0000000000457dc0 <main.main>: 457dc0: 49 3b 66 10 cmp 0x10(%r14),%rsp 457dc4: 76 41 jbe 457e07 <main.main+0x47> 457dc6: 48 83 ec 18 sub $0x18,%rsp 457dca: 48 89 6c 24 10 mov %rbp,0x10(%rsp) 457dcf: 48 8d 6c 24 10 lea 0x10(%rsp),%rbp 457dd4: b8 10 00 00 00 mov $0x10,%eax 457dd9: e8 a2 fe ff ff call 457c80 <main.fDefer> 457dde: 66 90 xchg %ax,%ax 457de0: 48 3d 0b 0e 00 00 cmp $0xe0b,%rax 457de6: 75 0a jne 457df2 <main.main+0x32> 457de8: 48 8b 6c 24 10 mov 0x10(%rsp),%rbp 457ded: 48 83 c4 18 add $0x18,%rsp 457df1: c3 ret 457df2: e8 c9 11 fb ff call 408fc0 <runtime.convT64> 457df7: 48 89 c3 mov %rax,%rbx 457dfa: 48 8d 05 bf 42 00 00 lea 0x42bf(%rip),%rax # 45c0c0 <type.*+0x40c0> 457e01: e8 7a 53 fd ff call 42d180 <runtime.gopanic> 457e06: 90 nop 457e07: e8 b4 cb ff ff call 4549c0 <runtime.morestack_noctxt.abi0> 457e0c: eb b2 jmp 457dc0 <main.main>
Go每日一题 今日（2022-03-25） - Go语言中文网 - Golang中文社区 https://studygolang.com/interview/question
func increaseA() int {
var i int
defer func() {
i++
}()
return i
}
func increaseB() (r int) {
defer func() {
r++
}()
return r
}
func main() {
fmt.Println(increaseA())
fmt.Println(increaseB())
}
