C++11 initializer_list 和 Range-based for loop 学习理解

win10 + vs2017

源码如下：

int main()

{

　　vector< int > numbers = { 1, 2, 3, 4, 5 };

　　for (auto num : numbers)

　　{

　　　　printf( "num = %d\n", num );

　　}

　　return 0;

}

汇编理解如下：

int main()
{
# 入栈
00933F63 sub         esp,150h
00933F69 push        ebx
00933F6A push        esi
00933F6B push        edi
00933F6C lea         edi,[ebp-150h]
00933F72 mov         ecx,54h
00933F77 mov         eax,0CCCCCCCCh
00933F7C rep stos    dword ptr es:[edi]
00933F7E mov         eax,dword ptr [__security_cookie (093E004h)]
00933F83 xor         eax,ebp
00933F85 mov         dword ptr [ebp-4],eax

vector< int > numbers = { 1, 2, 3, 4, 5 };

// memset( &numbers, 0x00, sizeof ( numbers ) );
// sizeof ( numbers ) == 10h
00933F88 push        10h
00933F8A lea         ecx,[numbers]
00933F8D call        std::vector<int,std::allocator<int> >::__autoclassinit2 (09314ABh)

// [ebp-14Ch, ebp-138h) 这段内存是5个整形(20个字节)，分别赋值为1,2,3,4,5
00933F92 mov         dword ptr [ebp-14Ch],1
00933F9C mov         dword ptr [ebp-148h],2
00933FA6 mov         dword ptr [ebp-144h],3
00933FB0 mov         dword ptr [ebp-140h],4
00933FBA mov         dword ptr [ebp-13Ch],5

// 创建allocator对象，供后面vector构造使用，地址为 ebp-111h
00933FC4 lea         ecx,[ebp-111h]
00933FCA call        std::allocator<int>::allocator<int> (0931163h)
00933FCF push        eax

// std::initializer_list<int> 构造
// initializer_list(const _Elem *_First_arg, const _Elem *_Last_arg)
00933FD0 lea         eax,[ebp-138h]
00933FD6 push        eax
00933FD7 lea         ecx,[ebp-14Ch]
00933FDD push        ecx
00933FDE lea         ecx,[ebp-124h]
00933FE4 call        std::initializer_list<int>::initializer_list<int> (09314A6h)

// vector 构造
// vector(initializer_list<_Ty> _Ilist, const _Alloc& _Al = _Alloc())
// _Al参数是在 00933FCF 位置压栈的
// _Ilist参数是按值传递，将成员_First和_Last分两次压栈，对应下面4行
00933FE9 mov         edx,dword ptr [eax+4]
00933FEC push        edx
00933FED mov         eax,dword ptr [eax]
00933FEF push        eax
00933FF0 lea         ecx,[numbers]
00933FF3 call        std::vector<int,std::allocator<int> >::vector<int,std::allocator<int> > (0931168h)

for (auto num : numbers)

// std::vector<int,std::allocator<int> >::begin() 结果保存在 dword ptr [ebp-30h]
00933FF8 lea         eax,[numbers]
00933FFB mov         dword ptr [ebp-24h],eax
00933FFE mov         ecx,dword ptr [ebp-24h]
00934001 call        std::vector<int,std::allocator<int> >::_Unchecked_begin (09311FEh)
00934006 mov         dword ptr [ebp-30h],eax

// std::vector<int,std::allocator<int> >::end() 结果保存在 dword ptr [ebp-3Ch]
00934009 mov         ecx,dword ptr [ebp-24h]
0093400C call        std::vector<int,std::allocator<int> >::_Unchecked_end (09312C1h)
00934011 mov         dword ptr [ebp-3Ch],eax

// 跳转 for 循环的条件比较
00934014 jmp main+0BFh (093401Fh)

// 迭代器加1
00934016 mov         eax,dword ptr [ebp-30h]
00934019 add         eax,4
0093401C mov         dword ptr [ebp-30h],eax

// eax = dword ptr [ebp-30h]
// eax 和 vector::end() 比较，如果相等则跳出循环
0093401F mov         eax,dword ptr [ebp-30h]
00934022 cmp         eax,dword ptr [ebp-3Ch]
00934025 je          main+0E2h (0934042h)

// 将 dword ptr [ebp-30h] 迭代器指向的整形数值取出来，放到 dword ptr [ebp-48h]
00934027 mov         eax,dword ptr [ebp-30h]
0093402A mov         ecx,dword ptr [eax]
0093402C mov         dword ptr [ebp-48h],ecx
   {
       printf( "num = %d\n", num );

// 从 dword ptr [ebp-48h] 取出整形数值，压栈
// 将 "num = %d\n" 压栈
// 调用 printf
0093402F mov         eax,dword ptr [ebp-48h]
00934032 push        eax
00934033 push        offset string "num = %d\n" (093BC88h)
00934038 call        _printf (093153Ch)
0093403D add         esp,8
   }

// 跳转到迭代器加1位置
00934040 jmp main+0B6h (0934016h)

return 0;
00934042 mov dword ptr [ebp-130h],0

// vecotr析构
0093404C lea ecx,[numbers]
0093404F call std::vector<int,std::allocator<int> >::~vector<int,std::allocator<int> > (0931078h)

// 将返回值0放入eax寄存器
00934054 mov eax,dword ptr [ebp-130h]
}

// 出栈
0093405A push        edx
0093405B mov         ecx,ebp
0093405D push        eax
0093405E lea         edx,ds:[93408Ch]
00934064 call        @_RTC_CheckStackVars@8 (09313F7h)
00934069 pop         eax
0093406A pop         edx
0093406B pop         edi
0093406C pop         esi
0093406D pop         ebx
0093406E mov         ecx,dword ptr [ebp-4]
00934071 xor         ecx,ebp
00934073 call        @__security_check_cookie@4 (0931415h)
00934078 add         esp,150h
0093407E cmp         ebp,esp
00934080 call        __RTC_CheckEsp (0931212h)
00934085 mov         esp,ebp
00934087 pop         ebp
00934088 ret

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C++11 initializer_list 和 Range-based for loop 学习理解

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