代码
nclude <iostream>
using namespace std;
int main()
{
int b = 9;
auto d = [](int a){cout<<"a="<<a<<endl;};
auto c = [&](int a){cout<<"a="<<a<<"b="<<b<<endl;};
d(3);
c(4);
}
汇编
这个也会生成一个汇编函数。带入的参数。如果是捕获引用，就会将引用地址通过 rax 传递栈地址，到lamda函数里，使用。
lamda函数名包含：父函数名：：{lambda（返回类型）编号}：：operator()(参数类型）const
0000000000400876 <main::{lambda(int)#1}::operator()(int) const>:
400876: 55 push %rbp
400877: 48 89 e5 mov %rsp,%rbp
40087a: 48 83 ec 10 sub $0x10,%rsp
40087e: 48 89 7d f8 mov %rdi,-0x8(%rbp)
400882: 89 75 f4 mov %esi,-0xc(%rbp)
400885: be 49 0a 40 00 mov $0x400a49,%esi
40088a: bf 60 10 60 00 mov $0x601060,%edi
40088f: e8 ac fe ff ff callq 400740 <basic_ostream<char, char_traits<char> >& operator<< <char_traits<char> >(basic_ostream<char, char_traits<char> >&, char const*)@plt>
s 400894: 48 89 c2 mov %rax,%rdx
400897: 8b 45 f4 mov -0xc(%rbp),%eax
40089a: 89 c6 mov %eax,%esi
40089c: 48 89 d7 mov %rdx,%rdi
40089f: e8 cc fe ff ff callq 400770 <std::ostream::operator<<(int)@plt>
4008a4: be 20 07 40 00 mov $0x400720,%esi
4008a9: 48 89 c7 mov %rax,%rdi
4008ac: e8 9f fe ff ff callq 400750 <std::ostream::operator<<(std::ostream& (*)(std::ostream&))@plt>
4008b1: 90 nop
4008b2: c9 leaveq
4008b3: c3 retq
00000000004008b4 <main::{lambda(int)#2}::operator()(int) const>:
4008b4: 55 push %rbp
4008b5: 48 89 e5 mov %rsp,%rbp
4008b8: 48 83 ec 10 sub $0x10,%rsp
4008bc: 48 89 7d f8 mov %rdi,-0x8(%rbp)
4008c0: 89 75 f4 mov %esi,-0xc(%rbp)
4008c3: be 49 0a 40 00 mov $0x400a49,%esi
4008c8: bf 60 10 60 00 mov $0x601060,%edi
4008cd: e8 6e fe ff ff callq 400740 <basic_ostream<char, char_traits<char> >& operator<< <char_traits<char> >(basic_ostream<char, char_traits<char> >&, char const*)@plt>
s 4008d2: 48 89 c2 mov %rax,%rdx 将传进来的引用地址放到，rdx
4008d5: 8b 45 f4 mov -0xc(%rbp),%eax
4008d8: 89 c6 mov %eax,%esi
4008da: 48 89 d7 mov %rdx,%rdi 将引用放到第一个参数
4008dd: e8 8e fe ff ff callq 400770 <std::ostream::operator<<(int)@plt>
4008e2: be 4c 0a 40 00 mov $0x400a4c,%esi
4008e7: 48 89 c7 mov %rax,%rdi
4008ea: e8 51 fe ff ff callq 400740 <std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)@plt>
4008ef: 48 89 c2 mov %rax,%rdx
4008f2: 48 8b 45 f8 mov -0x8(%rbp),%rax
4008f6: 48 8b 00 mov (%rax),%rax
4008f9: 8b 00 mov (%rax),%eax
4008fb: 89 c6 mov %eax,%esi
4008fd: 48 89 d7 mov %rdx,%rdi
400900: e8 6b fe ff ff callq 400770 <std::ostream::operator<<(int)@plt>
400905: be 20 07 40 00 mov $0x400720,%esi
40090a: 48 89 c7 mov %rax,%rdi
40090d: e8 3e fe ff ff callq 400750 <std::ostream::operator<<(std::ostream& (*)(std::ostream&))@plt>
400912: 90 nop
400913: c9 leaveq
400914: c3 retq
0000000000400915 <main>:
400915: 55 push %rbp
400916: 48 89 e5 mov %rsp,%rbp
400919: 48 83 ec 10 sub $0x10,%rsp
40091d: c7 45 fc 09 00 00 00 movl $0x9,-0x4(%rbp) 变量 b；9
400924: 48 8d 45 fc lea -0x4(%rbp),%rax 变量b的地址放到rax
400928: 48 89 45 f0 mov %rax,-0x10(%rbp) 变量的地址放到栈 0x10 到0x8
40092c: 48 8d 45 fb lea -0x5(%rbp),%rax rbp - 5 放到rax 为什么要在栈上分配一个内存传递过去，因为只有一个参数。
400930: be 03 00 00 00 mov $0x3,%esi 第二个参数
400935: 48 89 c7 mov %rax,%rdi 第一个参数
400938: e8 39 ff ff ff callq 400876 <main::{lambda(int)#1}::operator()(int) const>
40093d: 48 8d 45 f0 lea -0x10(%rbp),%rax 将要捕获的引用放到rax
400941: be 04 00 00 00 mov $0x4,%esi
400946: 48 89 c7 mov %rax,%rdi
400949: e8 66 ff ff ff callq 4008b4 <main::{lambda(int)#2}::operator()(int) const>
40094e: b8 00 00 00 00 mov $0x0,%eax
400953: c9 leaveq
400954: c3 retq
解释
在汇编里出现的符号，可以参考下面这个文章理解
00000000004008b4 <main::{lambda(int)#2}::operator()(int) const>:
https://blog.csdn.net/zhangxiangdavaid/article/details/44064765
https://web.mst.edu/~nmjxv3/articles/lambdas.html
这个出处是哪里？没找到文档。
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