{"id":234253,"date":"2020-12-29T09:11:23","date_gmt":"2020-12-29T01:11:23","guid":{"rendered":"http:\/\/4563.org\/?p=234253"},"modified":"2020-12-29T09:11:23","modified_gmt":"2020-12-29T01:11:23","slug":"%e8%af%b7%e6%95%99%e4%b8%80%e4%b8%aa-c%e9%97%ae%e9%a2%98%ef%bc%8c%e4%b8%ba%e4%bb%80%e4%b9%88%e5%8a%a0%e4%ba%86-inline-%e5%8f%8d%e8%80%8c%e6%95%88%e7%8e%87%e9%99%8d%e4%bd%8e%e4%ba%86","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=234253","title":{"rendered":"\u8bf7\u6559\u4e00\u4e2a C++\u95ee\u9898\uff0c\u4e3a\u4ec0\u4e48\u52a0\u4e86 inline \u53cd\u800c\u6548\u7387\u964d\u4f4e\u4e86"},"content":{"rendered":"
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\u8bf7\u6559\u4e00\u4e2a C++\u95ee\u9898\uff0c\u4e3a\u4ec0\u4e48\u52a0\u4e86 inline \u53cd\u800c\u6548\u7387\u964d\u4f4e\u4e86 <\/h1>\n

<\/p>\n

\n
\u8cc7\u6df1\u5927\u4f6c : zvl0reqglvd <\/span> <\/i> 6<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n

\u8001\u54e5\u4eec\uff0c\u8bf7\u6559\u4e00\u4e0b\u4e0b\u9762\u7684\u7a0b\u5e8f\u662f\u56e0\u4e3a\u4ec0\u4e48\u539f\u56e0\u9020\u6210\u7684\uff1f<\/p>\n

#include <iostream> #include <chrono> using namespace std;  class Runtime{ private:     std::chrono::high_resolution_clock::time_point _start, _end; public:     Runtime(){  start();     }          void start(){  _start = std::chrono::high_resolution_clock::now();     }     void end() {  _end = std::chrono::high_resolution_clock::now();     }     long long spend() {  return std::chrono::duration_cast<std::chrono::nanoseconds>(_end - _start).count();     }     void printTime() {  end();  std::cout << \"time = \"     << spend()\/1000000 << \"\/ms = \"\/\/\u6beb\u79d2     << spend()\/1000 << \"\/us = \"\/\/\u5fae\u79d2     << spend() << \"\/ns\" << std::endl;\/\/\u7eb3\u79d2     } };  const int N = 1e5; int x[N]; int y[N]; int z[N];  \/\/inline int calc(int a, int b) {     return a + b; }  int main(){     Runtime r;     for (int i=0; i<N; ++i) {  for (int j=0; j<N; ++j) {      for (int k=0; k<N; ++k)   z[i] = calc(y[j], x[k]);         \/\/z[i] = y[j] + x[k];  }     }     r.printTime(); } <\/code><\/pre>\n
\u52a0\u4e86 inline \u6bd4\u4e0d\u52a0\u6162\u4e00\u500d\uff0c\u4e0d\u662f\u8bf4 inline \u4f1a\u51cf\u5c11\u51fd\u6570\u538b\u6808\u51fa\u6808\u7684\u65f6\u95f4\u5f00\u9500\uff0c\u76f8\u5f53\u4e8e\u76f4\u63a5\u5728\u8c03\u7528\u70b9\u63d2\u5165\u4ee3\u7801\u561b\uff0c\u4f46\u662f\uff0c\u5b9e\u9645\u4e0a\u5f00\u9500\u6bd4\u4e0d\u52a0 inline \u6162\u4e00\u500d\uff0c\u4e0d\u52a0 inline \u7684\u5f00\u9500\u548c\u4e0b\u9762\u6ce8\u91ca\u7684\u90a3\u53e5\u7684\u5f00\u9500\u5dee\u4e0d\u591a\u3002\u611f\u89c9\u5f88\u5947\u602a\uff0c\u96be\u9053\u662f\u7f16\u8bd1\u5668\u81ea\u52a8\u6dfb\u52a0\u4e86 inline \uff1f<\/p>\n
\u8bf7\u95ee\u662f\u4ec0\u4e48\u539f\u56e0\u9020\u6210\u7684\u554a\uff1f<\/p>\n<\/p><\/div>\n
 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (17<\/span>)        <\/div>\n
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    \n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : BrettD <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u770b\u4e00\u4e0b\u751f\u6210\u7684\u6c47\u7f16\u4ee3\u7801\u662f\u5565                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : Huelse <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u636e\u6211\u6240\u77e5\uff0c\u4e00\u4e9b\u7f16\u8bd1\u5668\u662f\u4f1a\u5728\u7f16\u8bd1 release \u6216\u8005\u6709\u5176\u4ed6\u7f16\u8bd1\u9009\u9879\u7684\u65f6\u5019\u4f1a\u81ea\u52a8\u7ed9`return a+b`\u8fd9\u79cd\u81ea\u52a8\u52a0 inline                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : crclz <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 1. \u770b\u770b\u6c47\u7f16\uff0c\u7528 vscode \u6bd4\u8f83\u4e00\u4e0b\uff08\u53f3\u952e\uff09
    2. \u5f00-O1 \u6216\u8005-O2\uff0c\u518d\u6d4b\u4e00\u4e0b\u901f\u5ea6\uff0c\u5e76\u4e14\u518d\u6bd4\u8f83\u4e00\u4e0b\u6c47\u7f16\u4ee3\u7801                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : YouLMAO <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 for (int i=0; i<N; ++i) {
     z[i] = y[N] + x[N];
    }<\/p>\n
    \u8fd9\u5c31\u662f gcc \u4f18\u5316\u7684\u7ed3\u679c                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : GeruzoniAnsasu <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u9996\u5148\u5f00\u4e0d\u5f00\u4f18\u5316\u5f71\u54cd\u5f88\u5927\uff0c\u5982\u679c\u88ab inline \u7684\u4ee3\u7801\u672c\u8eab side effect \u6bd4\u8f83\u591a\uff0c\u672a\u4f18\u5316\u60c5\u51b5\u4e0b\u53ef\u80fd\u4f1a\u989d\u5916\u591a\u505a\u5f88\u591a\u4e8b\u60c5\uff0c\u6bd4\u5982\u9891\u7e41\u8bfb\u5199\u53d8\u91cf\u7684\u5185\u5b58\uff0c\u672c\u6765\u8fd9\u90fd\u662f\u5b8c\u5168\u4e0d\u9700\u8981\u7684<\/p>\n
    \u53e6\u5916\u73b0\u5728 x64 \u7684 fastcall abi\uff0c\u51fd\u6570\u8c03\u7528\u5df2\u7ecf\u6ca1\u6709\u8bbf\u95ee\u5185\u5b58\u51fa\u5165\u6808\u7684\u5f00\u9500\u4e86\uff0c\u90fd\u53ef\u4ee5\u7528\u5bc4\u5b58\u5668\u89e3\u51b3\uff0c\u6240\u4ee5 inline \u7701\u7565\u6389\u4e86\u51fd\u6570\u51fa\u5165\u6808\u8fd9\u4e2a\u89c2\u5ff5\u4e5f\u5df2\u7ecf\u662f\u8fc7\u65f6\u751a\u81f3\u9519\u8bef\u7684\u4e86<\/p>\n
    \u518d\u7136\u540e\uff0c\u4f17\u6240\u5468\u77e5 c++\u7f16\u8bd1\u5668\u884c\u4e3a\u5b66\u90fd\u53ea\u80fd\u9a6c\u540e\u70ae\uff0c\u81ea\u5df1\u770b\u4e00\u773c\u7f16\u8bd1\u51fa\u6765\u7684\u6c47\u7f16\u5c31\u90fd\u660e\u767d\u4e86                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : zvl0reqglvd <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8981\u7684\uff0c\u8c22\u8c22\u8001\u54e5\u4eec\uff0c\u97a0\u8eac\uff01\uff01                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : lifanxi <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u770b\u770b\u6c47\u7f16\u627e\u539f\u56e0\u3002<\/p>\n
    \u5177\u4f53\u662f\u4ec0\u4e48\u73af\u5883\u51fa\u73b0\u4e86\u4f60\u8bf4\u63cf\u8ff0\u7684\u73b0\u8c61\uff1f\u6211\u5728 gcc 8.3 \u4e0a\u91cd\u73b0\u4e0d\u51fa\u6765\u4f60\u8bf4\u7684\u73b0\u8c61\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : nightwitch <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 inline \u8fd9\u4e2a\u5173\u952e\u8bcd\u5efa\u8bae\u76f4\u63a5\u5fd8\u8bb0\u5b83\u6709\u5185\u8054\u5efa\u8bae\u8fd9\u4e2a\u529f\u80fd\uff0c\u56e0\u4e3a\u73b0\u5728\u7f16\u8bd1\u5668\u57fa\u672c\u4e0a\u65e0\u89c6 inline \u7684\u8fd9\u4e2a\u8bed\u4e49\u3002
    \u5982\u679c\u4f60\u771f\u7684\u786e\u5b9a\u8981\u5185\u8054\u4e00\u4e2a\u51fd\u6570\uff0cMSVC \u8981\u7528__forceinline , gcc \u8981\u7528__attribute__((always_inline))\u3002<\/p>\n
    inline \u8fd9\u4e2a\u5173\u952e\u8bcd\u73b0\u5728\u7684\u4e3b\u8981\u4f5c\u7528\u662f\u5141\u8bb8\u4e00\u4e2a\u7b26\u53f7\u5728\u4e0d\u540c\u7684\u7f16\u8bd1\u5355\u5143\u6709\u91cd\u590d\u7684\u5b9a\u4e49\uff0c\u8fd9\u6837\u5141\u8bb8\u4f60\u5728\u5934\u6587\u4ef6\u91cc\u5199\u51fa\u51fd\u6570\u5b9e\u73b0\u548c inline variable.                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : mxalbert1996 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4e0d\u77e5\u9053\u4f60\u8fd9\u4e2a\u662f\u4e0d\u662f\u8fd9\u79cd\u60c5\u51b5\uff0c\u4e0d\u8fc7 inline \u53ef\u80fd\u4f1a\u9020\u6210\u66f4\u591a cache miss \u4ece\u800c\u5f71\u54cd\u6027\u80fd\u3002
    https:\/\/en.wikipedia.org\/wiki\/Inline_expansion
    Inlining also imposes a cost on performance, due to the code expansion (due to duplication) hurting instruction cache performance.[6] This is most significant if, prior to expansion, the working set of the program (or a hot section of code) fit in one level of the memory hierarchy (e.g., L1 cache), but after expansion it no longer fits, resulting in frequent cache misses at that level. Due to the significant difference in performance at different levels of the hierarchy, this hurts performance considerably.                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : msg7086 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 gcc \u5e26\u4e0a\u4f18\u5316\u7f16\u8bd1\u51fa\u6765\u662f\u8fd9\u6837\u7684\u3002<\/p>\n
    main:
    \u3000\u3000\u3000\u3000 vpbroadcastd \u3000\u3000 ymm1, DWORD PTR x[rip+399996]
    \u3000\u3000\u3000\u3000 mov \u3000\u3000 eax, OFFSET FLAT:z
    \u3000\u3000\u3000\u3000 mov \u3000\u3000 ecx, OFFSET FLAT:y+400000
    .L3:
    \u3000\u3000\u3000\u3000 mov \u3000\u3000 edx, OFFSET FLAT:y
    .L2:
    \u3000\u3000\u3000\u3000 vpbroadcastd \u3000\u3000 ymm0, DWORD PTR [rdx]
    \u3000\u3000\u3000\u3000 add \u3000\u3000 rdx, 4
    \u3000\u3000\u3000\u3000 cmp \u3000\u3000 rcx, rdx
    \u3000\u3000\u3000\u3000 jne \u3000\u3000 .L2
    \u3000\u3000\u3000\u3000 vpaddd \u3000 ymm0, ymm1, ymm0
    \u3000\u3000\u3000\u3000 add \u3000\u3000 rax, 32
    \u3000\u3000\u3000\u3000 vmovdqa YMMWORD PTR [rax-32], ymm0
    \u3000\u3000\u3000\u3000 cmp \u3000\u3000 rax, OFFSET FLAT:z+400000
    \u3000\u3000\u3000\u3000 jne \u3000\u3000 .L3
    \u3000\u3000\u3000\u3000 xor \u3000\u3000 eax, eax
    \u3000\u3000\u3000\u3000 vzeroupper
    \u3000\u3000\u3000\u3000 ret
    z:
    \u3000\u3000\u3000\u3000.zero \u3000 400000
    y:
    \u3000\u3000\u3000\u3000.zero \u3000 400000
    x:
    \u3000\u3000\u3000\u3000.zero \u3000 400000<\/p>\n
    \u6253\u5f00 AVX2 \u4ee5\u540e\u4f1a\u76f4\u63a5\u6267\u884c VPADDD\uff0c\u4e0d\u4ec5\u4e0d\u4f1a\u8c03\u7528 calc\uff0c\u751a\u81f3\u4e0d\u4f1a\u8c03\u7528\u666e\u901a\u7684\u5bc4\u5b58\u5668\u52a0\u6cd5\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : codehz <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 (inline \u6709\u4f60\u8ba4\u4e3a\u7684\u6548\u679c\u8981\u4e48\u662f\u7f16\u8bd1\u5668\u7248\u672c\u592a\u65e7\uff0c\u8981\u4e48\u5c31\u662f\u4f60\u7528\u4e86 always_inline \u7b49\u79c1\u6709\u6269\u5c55\u3002\u3002\u3002
    \u6309\u73b0\u884c c++\u6807\u51c6\uff0cinline \u5173\u952e\u5b57\u4e0d\u518d\u4f5c\u4e3a\u5185\u8054\u4f7f\u7528\u4e86\uff09
    \u81f3\u4e8e\u4f60\u8fd9\u91cc\u7684\u95ee\u9898\uff0c\u4f60\u53ef\u80fd\u6ca1\u5f00\u4f18\u5316\u6d4b\u8bd5\u7684\u5427                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : 786375312123 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u770b\u770b\u4f60\u7684 vs \u4f18\u5316\u5f00\u6ca1\u5f00                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : no1xsyzy <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @mxalbert1996 \u6309\u4e3b\u4ee3\u7801\uff0c\u6ca1\u6709\u53cd\u590d\u5199 calc()\uff0c\u53d1\u751f\u5185\u8054\u76f8\u6bd4\u4e0d\u53d1\u751f\u5185\u8054\uff0c\u4e5f\u4e0d\u8fc7\u662f\u628a\u552f\u4e00\u4e00\u5904 calc(a, b) \u66ff\u6362\u4e3a a+b\uff0c\u5e76\u4e14\u8fd8\u53bb\u6389\u4e86 calc \u672c\u8eab\u7684\u5b9a\u4e49\uff0c\u53ef\u4ee5\u8bf4\u6307\u4ee4\u7684\u5185\u5b58\u5360\u7528\u53cd\u800c\u662f\u51cf\u5c11\u7684\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : codyfeng <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8fd9\u7c7b\u95ee\u9898\u5e94\u8be5\u628a\u7f16\u8bd1\u5668\u7248\u672c\u3001\u53c2\u6570\u90fd\u8d34\u51fa\u6765                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : mxT52CRuqR6o5 <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 https:\/\/godbolt.org\/
    \u4e0d\u5f00\u7f16\u8bd1\u4f18\u5316\u6211\u8fd9\u8fb9\u770b\u8fd9\u4e2a\u5728\u7ebf\u7684\u7f16\u8bd1\u5668\u7ed3\u679c
    gcc \u662f\u5b8c\u5168\u4e00\u6837\uff0cclang \u662f\u7f16\u8bd1\u51fa\u6765\u7684\u987a\u5e8f\u4e0d\u4e00\u6837\uff0c\u90fd\u6ca1\u6709 inline
    \u60f3\u8981\u5f04\u6e05\u533a\u522b\u80af\u5b9a\u662f\u8981\u770b\u6c47\u7f16\u7684\uff0c\u4e0d\u77e5\u9053\u4f60\u7528\u7684\u4ec0\u4e48\u7f16\u8bd1\u5668\u5f00\u7684\u4ec0\u4e48\u7f16\u8bd1\u9009\u9879                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : zvl0reqglvd <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @mxT52CRuqR6o5 \u8001\u54e5\u4f60\u597d\uff0c\u6211\u7528\u7684\u662f gcc9.2\uff0c\u7136\u540e\u8fd0\u884c\u7684\u662f g++ -g test.cpp -o test -lm -Wall -std=c++17 -O2 && test.exe \uff0c\u5f00\u4e86\u4f18\u5316\u7684\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : Gwkang <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u9891\u7e41\u8c03\u7528\u7684\u51fd\u6570\uff0c\u4e0d\u5185\u8054\u53ef\u4ee5\u63d0\u9ad8 CPU \u7f13\u5b58\u547d\u4e2d\u7387\uff0c\u4f60\u5185\u8054\u4e4b\u540e\u5c31\u6ca1\u6709\u4e86\u51fd\u6570\u8c03\u7528\u6808\uff0c\u6240\u4ee5\u6162                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"
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