Skip to content

P
Paddle

机器未来 / Paddle
与 Fork 源项目一致

Fork自 PaddlePaddle / Paddle

通知 1
Star 1
Fork 0
P
Paddle
切换分支/标签
查找文件 普通视图历史永久链接Permalink
block.html 52.6 KB
Newer Older
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 


<!DOCTYPE html>
<!--[if IE 8]><html class="no-js lt-ie9" lang="en" > <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js" lang="en" > <!--<![endif]-->
<head>
  <meta charset="utf-8">
  
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  
  <title>Design Doc: Block and Scope &mdash; PaddlePaddle  文档</title>
  

  
  

  

  
  
    

  

  
  
    <link rel="stylesheet" href="../_static/css/theme.css" type="text/css" />
  

  
  
        <link rel="index" title="索引"
              href="../genindex.html"/>
        <link rel="search" title="搜索" href="../search.html"/>
    <link rel="top" title="PaddlePaddle  文档" href="../index.html"/> 

  <link rel="stylesheet" href="https://cdn.jsdelivr.net/perfect-scrollbar/0.6.14/css/perfect-scrollbar.min.css" type="text/css" />
  <link rel="stylesheet" href="../_static/css/override.css" type="text/css" />
  <script>
  var _hmt = _hmt || [];
  (function() {
    var hm = document.createElement("script");
    hm.src = "//hm.baidu.com/hm.js?b9a314ab40d04d805655aab1deee08ba";
    var s = document.getElementsByTagName("script")[0]; 
    s.parentNode.insertBefore(hm, s);
  })();
  </script>

  

  
  <script src="../_static/js/modernizr.min.js"></script>

</head>

<body class="wy-body-for-nav" role="document">

  
  <header class="site-header">
    <div class="site-logo">
      <a href="/"><img src="../_static/images/PP_w.png"></a>
    </div>
    <div class="site-nav-links">
      <div class="site-menu">
        <a class="fork-on-github" href="https://github.com/PaddlePaddle/Paddle" target="_blank"><i class="fa fa-github"></i>Fork me on Github</a>
        <div class="language-switcher dropdown">
          <a type="button" data-toggle="dropdown">
            <span>English</span>
            <i class="fa fa-angle-up"></i>
            <i class="fa fa-angle-down"></i>
          </a>
          <ul class="dropdown-menu">
            <li><a href="/doc_cn">中文</a></li>
            <li><a href="/doc">English</a></li>
          </ul>
        </div>
        <ul class="site-page-links">
          <li><a href="/">Home</a></li>
        </ul>
      </div>
      <div class="doc-module">
        
        <ul>
<li class="toctree-l1"><a class="reference internal" href="../getstarted/index_cn.html">新手入门</a></li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
85 86 87 
<li class="toctree-l1"><a class="reference internal" href="../build_and_install/index_cn.html">安装与编译</a></li>
<li class="toctree-l1"><a class="reference internal" href="../howto/index_cn.html">进阶使用</a></li>
<li class="toctree-l1"><a class="reference internal" href="../dev/index_cn.html">开发标准</a></li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 
<li class="toctree-l1"><a class="reference internal" href="../api/index_cn.html">API</a></li>
<li class="toctree-l1"><a class="reference internal" href="../faq/index_cn.html">FAQ</a></li>
</ul>

        
<div role="search">
  <form id="rtd-search-form" class="wy-form" action="../search.html" method="get">
    <input type="text" name="q" placeholder="Search docs" />
    <input type="hidden" name="check_keywords" value="yes" />
    <input type="hidden" name="area" value="default" />
  </form>
</div>        
      </div>
    </div>
  </header>
  
  <div class="main-content-wrap">

    
    <nav class="doc-menu-vertical" role="navigation">
        
          
          <ul>
<li class="toctree-l1"><a class="reference internal" href="../getstarted/index_cn.html">新手入门</a><ul>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
112 113 
<li class="toctree-l2"><a class="reference internal" href="../getstarted/quickstart_cn.html">快速开始</a></li>
<li class="toctree-l2"><a class="reference internal" href="../getstarted/concepts/use_concepts_cn.html">基本使用概念</a></li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
114 115 
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 
<li class="toctree-l1"><a class="reference internal" href="../build_and_install/index_cn.html">安装与编译</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../build_and_install/pip_install_cn.html">使用pip安装</a></li>
<li class="toctree-l2"><a class="reference internal" href="../build_and_install/docker_install_cn.html">使用Docker安装运行</a></li>
<li class="toctree-l2"><a class="reference internal" href="../build_and_install/build_cn.html">用Docker编译和测试PaddlePaddle</a></li>
<li class="toctree-l2"><a class="reference internal" href="../build_and_install/build_from_source_cn.html">从源码编译</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../howto/index_cn.html">进阶使用</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../howto/cmd_parameter/index_cn.html">命令行参数设置</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../howto/cmd_parameter/use_case_cn.html">使用案例</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/cmd_parameter/arguments_cn.html">参数概述</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/cmd_parameter/detail_introduction_cn.html">细节描述</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../howto/cluster/index_cn.html">分布式训练</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../howto/cluster/preparations_cn.html">环境准备</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/cluster/cmd_argument_cn.html">启动参数说明</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/cluster/multi_cluster/index_cn.html">在不同集群中运行</a><ul>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/fabric_cn.html">使用fabric启动集群训练</a></li>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/openmpi_cn.html">在OpenMPI集群中提交训练作业</a></li>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/k8s_cn.html">Kubernetes单机训练</a></li>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/k8s_distributed_cn.html">Kubernetes分布式训练</a></li>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/k8s_aws_cn.html">Distributed PaddlePaddle Training on AWS with Kubernetes</a></li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
139 140 141 142 
</ul>
</li>
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
143 144 145 146 
<li class="toctree-l2"><a class="reference internal" href="../howto/capi/index_cn.html">C-API预测库</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../howto/capi/compile_paddle_lib_cn.html">安装与编译C-API预测库</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/capi/organization_of_the_inputs_cn.html">输入/输出数据组织</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/capi/workflow_of_capi_cn.html">C-API使用流程</a></li>
T
Deploy to GitHub Pages: 16fd9f18e304043a1035ad237884a93be354804c  
Travis CI 已提交
147 148 
</ul>
</li>
T
Deploy to GitHub Pages: 100dd4c5416f4f39a142f510a112b104d19f2028  
Travis CI 已提交
149 
<li class="toctree-l2"><a class="reference internal" href="../howto/rnn/index_cn.html">RNN模型</a><ul>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
150 151 152 153 
<li class="toctree-l3"><a class="reference internal" href="../howto/rnn/rnn_config_cn.html">RNN配置</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/rnn/recurrent_group_cn.html">Recurrent Group教程</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/rnn/hierarchical_layer_cn.html">支持双层序列作为输入的Layer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/rnn/hrnn_rnn_api_compare_cn.html">单双层RNN API对比介绍</a></li>
T
Deploy to GitHub Pages: 03c858a9bee98dbbcbedd7a6be886402a2e97609  
Travis CI 已提交
154 155 
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
156 
<li class="toctree-l2"><a class="reference internal" href="../howto/optimization/gpu_profiling_cn.html">GPU性能调优</a></li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
157 158 
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
159 160 161 
<li class="toctree-l1"><a class="reference internal" href="../dev/index_cn.html">开发标准</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../dev/contribute_to_paddle_cn.html">如何贡献代码</a></li>
<li class="toctree-l2"><a class="reference internal" href="../dev/write_docs_cn.html">如何贡献文档</a></li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
162 163 164 165 166 167 168 169 170 171 172 173 174 
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../api/index_cn.html">API</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../api/v2/model_configs.html">模型配置</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/activation.html">Activation</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/layer.html">Layers</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/evaluators.html">Evaluators</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/optimizer.html">Optimizer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/pooling.html">Pooling</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/networks.html">Networks</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/attr.html">Parameter Attribute</a></li>
</ul>
</li>
T
Deploy to GitHub Pages: d4d8f742a3bc4366bf410bc9ff29c0c32666bf60  
Travis CI 已提交
175 176 177 178 179 180 
<li class="toctree-l2"><a class="reference internal" href="../api/v2/data.html">数据访问</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/data/data_reader.html">Data Reader Interface</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/data/image.html">Image Interface</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/data/dataset.html">Dataset</a></li>
</ul>
</li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
181 
<li class="toctree-l2"><a class="reference internal" href="../api/v2/run_logic.html">训练与应用</a></li>
T
Deploy to GitHub Pages: 5ac72d95014e453c13a389248d2d2361a45a3402  
Travis CI 已提交
182 
<li class="toctree-l2"><a class="reference internal" href="../api/v2/fluid.html">Fluid</a><ul>
T
Deploy to GitHub Pages: 43262608442a7c3f11422d7a87c0be68ac3293d8  
Travis CI 已提交
183 184 185 186 187 188 189 190 191 192 193 
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/layers.html">layers</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/data_feeder.html">data_feeder</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/executor.html">executor</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/initializer.html">initializer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/evaluator.html">evaluator</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/nets.html">nets</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/optimizer.html">optimizer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/param_attr.html">param_attr</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/profiler.html">profiler</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/regularizer.html">regularizer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/io.html">io</a></li>
T
Deploy to GitHub Pages: 5ac72d95014e453c13a389248d2d2361a45a3402  
Travis CI 已提交
194 195 
</ul>
</li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
196 197 
</ul>
</li>
T
Deploy to GitHub Pages: a703a246428dd9f95775db102e338aebf93e9764  
Travis CI 已提交
198 199 200 201 202 203 204 205 
<li class="toctree-l1"><a class="reference internal" href="../faq/index_cn.html">FAQ</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../faq/build_and_install/index_cn.html">编译安装与单元测试</a></li>
<li class="toctree-l2"><a class="reference internal" href="../faq/model/index_cn.html">模型配置</a></li>
<li class="toctree-l2"><a class="reference internal" href="../faq/parameter/index_cn.html">参数设置</a></li>
<li class="toctree-l2"><a class="reference internal" href="../faq/local/index_cn.html">本地训练与预测</a></li>
<li class="toctree-l2"><a class="reference internal" href="../faq/cluster/index_cn.html">集群训练与预测</a></li>
</ul>
</li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 
</ul>

        
    </nav>
    
    <section class="doc-content-wrap">

      

 







<div role="navigation" aria-label="breadcrumbs navigation">
  <ul class="wy-breadcrumbs">
      
    <li>Design Doc: Block and Scope</li>
  </ul>
</div>
      
      <div class="wy-nav-content" id="doc-content">
        <div class="rst-content">
          <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
           <div itemprop="articleBody">
            
  <div class="section" id="design-doc-block-and-scope">
<span id="design-doc-block-and-scope"></span><h1>Design Doc: Block and Scope<a class="headerlink" href="#design-doc-block-and-scope" title="永久链接至标题"></a></h1>
<div class="section" id="the-representation-of-computation">
<span id="the-representation-of-computation"></span><h2>The Representation of Computation<a class="headerlink" href="#the-representation-of-computation" title="永久链接至标题"></a></h2>
<p>Both deep learning systems and programming languages help users describe computation procedures.  These systems use various representations of computation:</p>
<ul class="simple">
<li>Caffe, Torch, and Paddle: sequences of layers.</li>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
242 
<li>TensorFlow, Caffe2, Mxnet: graph of operators.</li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
243 244 245 246 247 
<li>PaddlePaddle: nested blocks, like C++ and Java programs.</li>
</ul>
</div>
<div class="section" id="block-in-programming-languages-and-deep-learning">
<span id="block-in-programming-languages-and-deep-learning"></span><h2>Block in Programming Languages and Deep Learning<a class="headerlink" href="#block-in-programming-languages-and-deep-learning" title="永久链接至标题"></a></h2>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
248 
<p>In programming languages, a block is a pair of curly braces that includes local variables definitions and a sequence of instructions or operators.</p>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
249 250 251 252 253 254 255 256 257 258 
<p>Blocks work with control flow structures like <code class="docutils literal"><span class="pre">if</span></code>, <code class="docutils literal"><span class="pre">else</span></code>, and <code class="docutils literal"><span class="pre">for</span></code>, which have equivalents in deep learning:</p>
<p>| programming languages | PaddlePaddle          |
|&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;|&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;|
| for, while loop       | RNN, WhileOp          |
| if, if-else, switch   | IfElseOp, SwitchOp    |
| sequential execution  | a sequence of layers  |</p>
<p>A key difference is that a C++ program describes a one pass computation, whereas a deep learning program describes both the forward and backward passes.</p>
</div>
<div class="section" id="stack-frames-and-the-scope-hierarchy">
<span id="stack-frames-and-the-scope-hierarchy"></span><h2>Stack Frames and the Scope Hierarchy<a class="headerlink" href="#stack-frames-and-the-scope-hierarchy" title="永久链接至标题"></a></h2>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
259 260 261 262 263 264 265 
<p>The existence of the backward pass makes the execution of a block of PaddlePaddle different from traditional programs:</p>
<p>| programming languages | PaddlePaddle                    |
|&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;|&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;|
| stack                 | scope hierarchy                 |
| stack frame           | scope                           |
| push at entering block| push at entering block          |
| pop at leaving block  | destroy when minibatch completes|</p>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
266 267 268 269 270 271 272 273 274 
<ol class="simple">
<li>In traditional programs:<ul>
<li>When the execution enters the left curly brace of a block, the runtime pushes a frame into the stack, where it realizes local variables.</li>
<li>After the execution leaves the right curly brace, the runtime pops the frame.</li>
<li>The maximum number of frames in the stack is the maximum depth of nested blocks.</li>
</ul>
</li>
<li>In PaddlePaddle<ul>
<li>When the execution enters a block, PaddlePaddle adds a new scope, where it realizes variables.</li>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
275 
<li>PaddlePaddle doesn&#8217;t pop a scope after the execution of the block because variables therein are used by the backward pass.  So it has a stack forest known as a <em>scope hierarchy</em>.</li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
276 
<li>The height of the highest tree is the maximum depth of nested blocks.</li>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
277 
<li>After the processing of a minibatch, PaddlePaddle destroys the scope hierarchy.</li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
278 279 280 281 282 283 284 285 286 287 
</ul>
</li>
</ol>
</div>
<div class="section" id="use-blocks-in-c-and-paddlepaddle-programs">
<span id="use-blocks-in-c-and-paddlepaddle-programs"></span><h2>Use Blocks in C++ and PaddlePaddle Programs<a class="headerlink" href="#use-blocks-in-c-and-paddlepaddle-programs" title="永久链接至标题"></a></h2>
<p>Let us consolidate the discussion by presenting some examples.</p>
<div class="section" id="blocks-with-if-else-and-ifelseop">
<span id="blocks-with-if-else-and-ifelseop"></span><h3>Blocks with <code class="docutils literal"><span class="pre">if-else</span></code> and <code class="docutils literal"><span class="pre">IfElseOp</span></code><a class="headerlink" href="#blocks-with-if-else-and-ifelseop" title="永久链接至标题"></a></h3>
<p>The following C++ programs shows how blocks are used with the <code class="docutils literal"><span class="pre">if-else</span></code> structure:</p>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
288 289 290 291 292 
<div class="highlight-c++"><div class="highlight"><pre><span></span><span class="k">namespace</span> <span class="n">pd</span> <span class="o">=</span> <span class="n">paddle</span><span class="p">;</span>

<span class="kt">int</span> <span class="n">x</span> <span class="o">=</span> <span class="mi">10</span><span class="p">;</span>
<span class="kt">int</span> <span class="n">y</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
<span class="kt">int</span> <span class="n">z</span> <span class="o">=</span> <span class="mi">10</span><span class="p">;</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
293 
<span class="kt">bool</span> <span class="n">cond</span> <span class="o">=</span> <span class="nb">false</span><span class="p">;</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
294 
<span class="kt">int</span> <span class="n">o1</span><span class="p">,</span> <span class="n">o2</span><span class="p">;</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
295 296 
<span class="k">if</span> <span class="p">(</span><span class="n">cond</span><span class="p">)</span> <span class="p">{</span>
  <span class="kt">int</span> <span class="n">z</span> <span class="o">=</span> <span class="n">x</span> <span class="o">+</span> <span class="n">y</span><span class="p">;</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
297 298 
  <span class="n">o1</span> <span class="o">=</span> <span class="n">z</span><span class="p">;</span>
  <span class="n">o2</span> <span class="o">=</span> <span class="n">pd</span><span class="o">::</span><span class="n">layer</span><span class="o">::</span><span class="n">softmax</span><span class="p">(</span><span class="n">z</span><span class="p">);</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
299 
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
300 301 302 
  <span class="kt">int</span> <span class="n">d</span> <span class="o">=</span> <span class="n">pd</span><span class="o">::</span><span class="n">layer</span><span class="o">::</span><span class="n">fc</span><span class="p">(</span><span class="n">z</span><span class="p">);</span>
  <span class="n">o1</span> <span class="o">=</span> <span class="n">d</span><span class="p">;</span>
  <span class="n">o2</span> <span class="o">=</span> <span class="n">d</span><span class="o">+</span><span class="mi">1</span><span class="p">;</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
303 304 305 306 307 308 
<span class="p">}</span>
</pre></div>
</div>
<p>An equivalent PaddlePaddle program from the design doc of the <a class="reference internal" href="if_else_op.html"><span class="doc">IfElseOp operator</span></a> is as follows:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">paddle</span> <span class="kn">as</span> <span class="nn">pd</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
309 310 311 312 313 314 
<span class="n">x</span> <span class="o">=</span> <span class="n">minibatch</span><span class="p">([</span><span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">,</span> <span class="mi">30</span><span class="p">])</span> <span class="c1"># shape=[None, 1]</span>
<span class="n">y</span> <span class="o">=</span> <span class="n">var</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span> <span class="c1"># shape=[1], value=1</span>
<span class="n">z</span> <span class="o">=</span> <span class="n">minibatch</span><span class="p">([</span><span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">,</span> <span class="mi">30</span><span class="p">])</span> <span class="c1"># shape=[None, 1]</span>
<span class="n">cond</span> <span class="o">=</span> <span class="n">larger_than</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="mi">15</span><span class="p">)</span> <span class="c1"># [false, true, true]</span>

<span class="n">ie</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">ifelse</span><span class="p">()</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
315 
<span class="k">with</span> <span class="n">ie</span><span class="o">.</span><span class="n">true_block</span><span class="p">():</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
316 317 
    <span class="n">d</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">layer</span><span class="o">.</span><span class="n">add_scalar</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">)</span>
    <span class="n">ie</span><span class="o">.</span><span class="n">output</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">pd</span><span class="o">.</span><span class="n">layer</span><span class="o">.</span><span class="n">softmax</span><span class="p">(</span><span class="n">d</span><span class="p">))</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
318 
<span class="k">with</span> <span class="n">ie</span><span class="o">.</span><span class="n">false_block</span><span class="p">():</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
319 320 321 
    <span class="n">d</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">layer</span><span class="o">.</span><span class="n">fc</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
    <span class="n">ie</span><span class="o">.</span><span class="n">output</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">d</span><span class="o">+</span><span class="mi">1</span><span class="p">)</span>
<span class="n">o1</span><span class="p">,</span> <span class="n">o2</span> <span class="o">=</span> <span class="n">ie</span><span class="p">(</span><span class="n">cond</span><span class="p">)</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
322 323 
</pre></div>
</div>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
324 325 
<p>In both examples, the left branch computes <code class="docutils literal"><span class="pre">x+y</span></code> and <code class="docutils literal"><span class="pre">softmax(x+y)</span></code>, the right branch computes <code class="docutils literal"><span class="pre">fc(x)</span></code> and <code class="docutils literal"><span class="pre">x+1</span></code> .</p>
<p>The difference is that variables in the C++ program contain scalar values, whereas those in the PaddlePaddle programs are mini-batches of instances.</p>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
326 327 328 
</div>
<div class="section" id="blocks-with-for-and-rnnop">
<span id="blocks-with-for-and-rnnop"></span><h3>Blocks with <code class="docutils literal"><span class="pre">for</span></code> and <code class="docutils literal"><span class="pre">RNNOp</span></code><a class="headerlink" href="#blocks-with-for-and-rnnop" title="永久链接至标题"></a></h3>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
329 
<p>The following RNN model in PaddlePaddle from the <a class="reference external" href="design/rnn.md">RNN design doc</a> :</p>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
330 331 332 333 334 335 336 337 
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">x</span> <span class="o">=</span> <span class="n">sequence</span><span class="p">([</span><span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">,</span> <span class="mi">30</span><span class="p">])</span> <span class="c1"># shape=[None, 1]</span>
<span class="n">m</span> <span class="o">=</span> <span class="n">var</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span> <span class="c1"># shape=[1]</span>
<span class="n">W</span> <span class="o">=</span> <span class="n">var</span><span class="p">(</span><span class="mf">0.314</span><span class="p">,</span> <span class="n">param</span><span class="o">=</span><span class="n">true</span><span class="p">)</span> <span class="c1"># shape=[1]</span>
<span class="n">U</span> <span class="o">=</span> <span class="n">var</span><span class="p">(</span><span class="mf">0.375</span><span class="p">,</span> <span class="n">param</span><span class="o">=</span><span class="n">true</span><span class="p">)</span> <span class="c1"># shape=[1]</span>

<span class="n">rnn</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">rnn</span><span class="p">()</span>
<span class="k">with</span> <span class="n">rnn</span><span class="o">.</span><span class="n">step</span><span class="p">():</span>
  <span class="n">h</span> <span class="o">=</span> <span class="n">rnn</span><span class="o">.</span><span class="n">memory</span><span class="p">(</span><span class="n">init</span> <span class="o">=</span> <span class="n">m</span><span class="p">)</span>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
338 
  <span class="n">h_prev</span> <span class="o">=</span> <span class="n">rnn</span><span class="o">.</span><span class="n">previous_memory</span><span class="p">(</span><span class="n">h</span><span class="p">)</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
339 
  <span class="n">a</span> <span class="o">=</span> <span class="n">layer</span><span class="o">.</span><span class="n">fc</span><span class="p">(</span><span class="n">W</span><span class="p">,</span> <span class="n">x</span><span class="p">)</span>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
340 
  <span class="n">b</span> <span class="o">=</span> <span class="n">layer</span><span class="o">.</span><span class="n">fc</span><span class="p">(</span><span class="n">U</span><span class="p">,</span> <span class="n">h_prev</span><span class="p">)</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
341 342 343 344 
  <span class="n">s</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="p">)</span>
  <span class="n">act</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">sigmoid</span><span class="p">(</span><span class="n">s</span><span class="p">)</span>
  <span class="n">rnn</span><span class="o">.</span><span class="n">update_memory</span><span class="p">(</span><span class="n">h</span><span class="p">,</span> <span class="n">act</span><span class="p">)</span>
  <span class="n">rnn</span><span class="o">.</span><span class="n">output</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="p">)</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
345 346 347 348 349 
<span class="n">o1</span><span class="p">,</span> <span class="n">o2</span> <span class="o">=</span> <span class="n">rnn</span><span class="p">()</span>
</pre></div>
</div>
<p>has its equivalent C++ program as follows</p>
<div class="highlight-c++"><div class="highlight"><pre><span></span><span class="kt">int</span><span class="o">*</span> <span class="n">x</span> <span class="o">=</span> <span class="p">{</span><span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">,</span> <span class="mi">30</span><span class="p">};</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
350 351 352 
<span class="kt">int</span><span class="o">*</span> <span class="n">m</span> <span class="o">=</span> <span class="p">{</span><span class="mi">0</span><span class="p">};</span>
<span class="kt">int</span><span class="o">*</span> <span class="n">W</span> <span class="o">=</span> <span class="p">{</span><span class="mf">0.314</span><span class="p">};</span>
<span class="kt">int</span><span class="o">*</span> <span class="n">U</span> <span class="o">=</span> <span class="p">{</span><span class="mf">0.375</span><span class="p">};</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
353 354 355 356 357 358 359 

<span class="kt">int</span> <span class="n">mem</span><span class="p">[</span><span class="k">sizeof</span><span class="p">(</span><span class="n">x</span><span class="p">)</span> <span class="o">/</span> <span class="k">sizeof</span><span class="p">(</span><span class="n">x</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span> <span class="o">+</span> <span class="mi">1</span><span class="p">];</span>
<span class="kt">int</span> <span class="n">o1</span><span class="p">[</span><span class="k">sizeof</span><span class="p">(</span><span class="n">x</span><span class="p">)</span> <span class="o">/</span> <span class="k">sizeof</span><span class="p">(</span><span class="n">x</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span> <span class="o">+</span> <span class="mi">1</span><span class="p">];</span>
<span class="kt">int</span> <span class="n">o2</span><span class="p">[</span><span class="k">sizeof</span><span class="p">(</span><span class="n">x</span><span class="p">)</span> <span class="o">/</span> <span class="k">sizeof</span><span class="p">(</span><span class="n">x</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span> <span class="o">+</span> <span class="mi">1</span><span class="p">];</span>
<span class="k">for</span> <span class="p">(</span><span class="kt">int</span> <span class="n">i</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span> <span class="n">i</span> <span class="o">&lt;=</span> <span class="k">sizeof</span><span class="p">(</span><span class="n">x</span><span class="p">)</span><span class="o">/</span><span class="k">sizeof</span><span class="p">(</span><span class="n">x</span><span class="p">[</span><span class="mi">0</span><span class="p">]);</span> <span class="o">++</span><span class="n">i</span><span class="p">)</span> <span class="p">{</span>
  <span class="kt">int</span> <span class="n">x</span> <span class="o">=</span> <span class="n">x</span><span class="p">[</span><span class="n">i</span><span class="o">-</span><span class="mi">1</span><span class="p">];</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">i</span> <span class="o">==</span> <span class="mi">1</span><span class="p">)</span> <span class="n">mem</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="n">m</span><span class="p">;</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
360 361 362 
  <span class="kt">int</span> <span class="n">a</span> <span class="o">=</span> <span class="n">W</span> <span class="o">*</span> <span class="n">x</span><span class="p">;</span>
  <span class="kt">int</span> <span class="n">b</span> <span class="o">=</span> <span class="n">Y</span> <span class="o">*</span> <span class="n">mem</span><span class="p">[</span><span class="n">i</span><span class="o">-</span><span class="mi">1</span><span class="p">];</span>
  <span class="kt">int</span> <span class="n">s</span> <span class="o">=</span> <span class="n">fc_out</span> <span class="o">+</span> <span class="n">hidden_out</span><span class="p">;</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
363 364 365 366 367 368 369 370 371 372 373 
  <span class="kt">int</span> <span class="n">act</span> <span class="o">=</span> <span class="n">sigmoid</span><span class="p">(</span><span class="n">sum</span><span class="p">);</span>
  <span class="n">mem</span><span class="p">[</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="n">act</span><span class="p">;</span>
  <span class="n">o1</span><span class="p">[</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="n">act</span><span class="p">;</span>
  <span class="n">o2</span><span class="p">[</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="n">hidden_out</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="compilation-and-execution">
<span id="compilation-and-execution"></span><h2>Compilation and Execution<a class="headerlink" href="#compilation-and-execution" title="永久链接至标题"></a></h2>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
374 375 
<p>Like TensorFlow, a PaddlePaddle program is written in Python. The first part describes a neural network as a protobuf message, and the rest executes the message for training or inference.</p>
<p>The generation of this protobuf message is similar to how a compiler generates a binary executable file. The execution of the message is similar to how the OS executes the binary file.</p>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 
</div>
<div class="section" id="the-binary-executable-file-format">
<span id="the-binary-executable-file-format"></span><h2>The &#8220;Binary Executable File Format&#8221;<a class="headerlink" href="#the-binary-executable-file-format" title="永久链接至标题"></a></h2>
<p>The definition of the protobuf message is as follows:</p>
<div class="highlight-protobuf"><div class="highlight"><pre><span></span><span class="kd">message</span> <span class="nc">BlockDesc</span> <span class="p">{</span>
  <span class="k">repeated</span> <span class="n">VarDesc</span> <span class="na">vars</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
  <span class="k">repeated</span> <span class="n">OpDesc</span> <span class="na">ops</span> <span class="o">=</span> <span class="mi">2</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>The step net in above RNN example would look like</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">BlockDesc</span> <span class="p">{</span>
  <span class="nb">vars</span> <span class="o">=</span> <span class="p">{</span>
    <span class="n">VarDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="n">x</span>
    <span class="n">VarDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="n">h</span>
    <span class="n">VarDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="n">fc_out</span>
    <span class="n">VarDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="n">hidden_out</span>
    <span class="n">VarDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="nb">sum</span>
    <span class="n">VarDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="n">act</span>
  <span class="p">}</span>
  <span class="n">ops</span> <span class="o">=</span> <span class="p">{</span>
    <span class="n">OpDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="n">matmul</span>
    <span class="n">OpDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="n">add_two</span>
    <span class="n">OpDesc</span> <span class="p">{</span><span class="o">...</span><span class="p">}</span> <span class="o">//</span> <span class="n">sigmoid</span>
  <span class="p">}</span>
<span class="p">};</span>
</pre></div>
</div>
<p>Also, the RNN operator in above example is serialized into a protobuf message of type <code class="docutils literal"><span class="pre">OpDesc</span></code> and would look like:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">OpDesc</span> <span class="p">{</span>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
406 407 
  <span class="n">inputs</span> <span class="o">=</span> <span class="p">{</span><span class="mi">0</span><span class="p">}</span> <span class="o">//</span> <span class="n">the</span> <span class="n">index</span> <span class="n">of</span> <span class="n">x</span> <span class="ow">in</span> <span class="nb">vars</span> <span class="n">of</span> <span class="n">BlockDesc</span> <span class="n">above</span>
  <span class="n">outputs</span> <span class="o">=</span> <span class="p">{</span><span class="mi">5</span><span class="p">,</span> <span class="mi">3</span><span class="p">}</span> <span class="o">//</span> <span class="n">indices</span> <span class="n">of</span> <span class="n">act</span> <span class="ow">and</span> <span class="n">hidden_out</span> <span class="ow">in</span> <span class="nb">vars</span> <span class="n">of</span> <span class="n">BlockDesc</span> <span class="n">above</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
408 
  <span class="n">attrs</span> <span class="p">{</span>
T
Deploy to GitHub Pages: 07ea9adec0531402bc31906d6ae85edaf96f413b  
Travis CI 已提交
409 
    <span class="s2">&quot;states&quot;</span> <span class="p">:</span> <span class="p">{</span><span class="mi">1</span><span class="p">}</span> <span class="o">//</span> <span class="n">the</span> <span class="n">index</span> <span class="n">of</span> <span class="n">h</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
410 411 412 413 414 415 416 417 418 419 
    <span class="s2">&quot;step_net&quot;</span> <span class="p">:</span> <span class="o">&lt;</span><span class="n">above</span> <span class="n">step</span> <span class="n">net</span><span class="o">&gt;</span>
  <span class="p">}</span>
<span class="p">};</span>
</pre></div>
</div>
<p>This <code class="docutils literal"><span class="pre">OpDesc</span></code> value is in the <code class="docutils literal"><span class="pre">ops</span></code> field of the <code class="docutils literal"><span class="pre">BlockDesc</span></code> value representing the global block.</p>
</div>
<div class="section" id="the-compilation-of-blocks">
<span id="the-compilation-of-blocks"></span><h2>The Compilation of Blocks<a class="headerlink" href="#the-compilation-of-blocks" title="永久链接至标题"></a></h2>
<p>During the generation of the Protobuf message, the Block should store VarDesc (the Protobuf message which describes Variable) and OpDesc (the Protobuf message which describes Operator).</p>
T
Deploy to GitHub Pages: e0ae76f222c5dd2484ed0ee9b5d013ff937c5cbb  
Travis CI 已提交
420 421 
<p>VarDesc in a block should have its name scope to avoid local variables affecting parent block&#8217;s name scope.
Child block&#8217;s name scopes should inherit the parent&#8217;s so that OpDesc in child block can reference a VarDesc that is stored in the parent block. For example:</p>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
422 
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">a</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">Variable</span><span class="p">(</span><span class="n">shape</span><span class="o">=</span><span class="p">[</span><span class="mi">20</span><span class="p">,</span> <span class="mi">20</span><span class="p">])</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
423 424 425 
<span class="n">b</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">fc</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">params</span><span class="o">=</span><span class="p">[</span><span class="s2">&quot;fc.w&quot;</span><span class="p">,</span> <span class="s2">&quot;fc.b&quot;</span><span class="p">])</span>

<span class="n">rnn</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">create_rnn</span><span class="p">()</span>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
426 
<span class="k">with</span> <span class="n">rnn</span><span class="o">.</span><span class="n">stepnet</span><span class="p">():</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
427 
    <span class="n">x</span> <span class="o">=</span> <span class="n">a</span><span class="o">.</span><span class="n">as_step_input</span><span class="p">()</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
428 429 
    <span class="c1"># reuse fc&#39;s parameter</span>
    <span class="n">fc_without_b</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">get_variable</span><span class="p">(</span><span class="s2">&quot;fc.w&quot;</span><span class="p">)</span>
T
Deploy to GitHub Pages: bfe6dcb5d345b3a734c2d496a97bffa184dfbbd4  
Travis CI 已提交
430 
    <span class="n">rnn</span><span class="o">.</span><span class="n">output</span><span class="p">(</span><span class="n">fc_without_b</span><span class="p">)</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
431 432 433 434 

<span class="n">out</span> <span class="o">=</span> <span class="n">rnn</span><span class="p">()</span>
</pre></div>
</div>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
435 
<p>The method <code class="docutils literal"><span class="pre">pd.get_variable</span></code> can help retrieve a Variable by the name. The Variable may be stored in a parent block, but might be retrieved in a child block, so block should have a variable scope that supports inheritance.</p>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
436 437 
<p>In compiler design, the symbol table is a data structure created and maintained by compilers to store information about the occurrence of various entities such as variable names, function names, classes, etc.</p>
<p>To store the definition of variables and operators, we define a C++ class <code class="docutils literal"><span class="pre">SymbolTable</span></code>, like the one used in compilers.</p>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
438 
<p><code class="docutils literal"><span class="pre">SymbolTable</span></code> can do the following:</p>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
439 440 
<ul class="simple">
<li>store the definitions (some names and attributes) of variables and operators,</li>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
441 442 
<li>verify if a variable was declared,</li>
<li>make it possible to implement type checking (offer Protobuf message pointers to <code class="docutils literal"><span class="pre">InferShape</span></code> handlers).</li>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
443 444 445 446 447 448 449 450 451 
</ul>
<div class="highlight-c++"><div class="highlight"><pre><span></span><span class="c1">// Information in SymbolTable is enough to trace the dependency graph. So maybe</span>
<span class="c1">// the Eval() interface takes a SymbolTable is enough.</span>
<span class="k">class</span> <span class="nc">SymbolTable</span> <span class="p">{</span>
 <span class="k">public</span><span class="o">:</span>
  <span class="n">SymbolTable</span><span class="p">(</span><span class="n">SymbolTable</span><span class="o">*</span> <span class="n">parent</span><span class="p">)</span> <span class="o">:</span> <span class="n">parent_</span><span class="p">(</span><span class="n">parent</span><span class="p">)</span> <span class="p">{}</span>

  <span class="n">OpDesc</span><span class="o">*</span> <span class="n">NewOp</span><span class="p">(</span><span class="k">const</span> <span class="n">string</span><span class="o">&amp;</span> <span class="n">name</span><span class="o">=</span><span class="s">&quot;&quot;</span><span class="p">);</span>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
452 453 454 
  <span class="c1">// TODO determine whether name is generated by python or C++.</span>
  <span class="c1">// Currently assume that a unique name will be generated by C++ if the</span>
  <span class="c1">// argument name is left default.</span>
T
Deploy to GitHub Pages: e593113a84a6227e8fc98875f66b9b865c6bc17b  
Travis CI 已提交
455 
  <span class="n">VarDesc</span><span class="o">*</span> <span class="nf">Var</span><span class="p">(</span><span class="k">const</span> <span class="n">string</span><span class="o">&amp;</span> <span class="n">name</span><span class="o">=</span><span class="s">&quot;&quot;</span><span class="p">);</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
456
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
457 
  <span class="c1">// find a VarDesc by name, if recursive is true, find parent&#39;s SymbolTable</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
458 459 460 461 462 
  <span class="c1">// recursively.</span>
  <span class="c1">// this interface is introduced to support InferShape, find protobuf messages</span>
  <span class="c1">// of variables and operators, pass pointers into InferShape.</span>
  <span class="c1">//</span>
  <span class="c1">// NOTE maybe some C++ classes such as VarDescBuilder and OpDescBuilder should</span>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
463 
  <span class="c1">// be proposed and embedded into pybind to enable python operation on C++ pointers.</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 
  <span class="n">VarDesc</span><span class="o">*</span> <span class="nf">FindVar</span><span class="p">(</span><span class="k">const</span> <span class="n">string</span><span class="o">&amp;</span> <span class="n">name</span><span class="p">,</span> <span class="kt">bool</span> <span class="n">recursive</span><span class="o">=</span><span class="nb">true</span><span class="p">);</span>

  <span class="n">OpDesc</span><span class="o">*</span> <span class="nf">FindOp</span><span class="p">(</span><span class="k">const</span> <span class="n">string</span><span class="o">&amp;</span> <span class="n">name</span><span class="p">);</span>

  <span class="n">BlockDesc</span> <span class="nf">Compile</span><span class="p">()</span> <span class="k">const</span><span class="p">;</span>

 <span class="k">private</span><span class="o">:</span>
  <span class="n">SymbolTable</span><span class="o">*</span> <span class="n">parent_</span><span class="p">;</span>

  <span class="n">map</span><span class="o">&lt;</span><span class="n">string</span><span class="p">,</span> <span class="n">OpDesc</span><span class="o">&gt;</span> <span class="n">ops_</span><span class="p">;</span>
  <span class="n">map</span><span class="o">&lt;</span><span class="n">string</span><span class="p">,</span> <span class="n">VarDesc</span><span class="o">&gt;</span> <span class="n">vars_</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
<p>After all the description of variables and operators is added into SymbolTable,
the block has enough information to run.</p>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
480 
<p>The <code class="docutils literal"><span class="pre">Block</span></code> class takes a <code class="docutils literal"><span class="pre">BlockDesc</span></code> as input, and provides <code class="docutils literal"><span class="pre">Run</span></code> and <code class="docutils literal"><span class="pre">InferShape</span></code> functions.</p>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 
<div class="highlight-c++"><div class="highlight"><pre><span></span><span class="k">namespace</span> <span class="p">{</span>

<span class="k">class</span> <span class="nc">Block</span> <span class="o">:</span> <span class="n">OperatorBase</span> <span class="p">{</span>
<span class="k">public</span><span class="o">:</span>
  <span class="n">Block</span><span class="p">(</span><span class="k">const</span> <span class="n">BlockDesc</span><span class="o">&amp;</span> <span class="n">desc</span><span class="p">)</span> <span class="n">desc_</span><span class="p">(</span><span class="n">desc</span><span class="p">)</span> <span class="p">{}</span>

  <span class="kt">void</span> <span class="n">InferShape</span><span class="p">(</span><span class="k">const</span> <span class="n">framework</span><span class="o">::</span><span class="n">Scope</span><span class="o">&amp;</span> <span class="n">scope</span><span class="p">)</span> <span class="k">const</span> <span class="k">override</span> <span class="p">{</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">symbols_ready_</span><span class="p">)</span> <span class="p">{</span>
      <span class="n">CreateVariables</span><span class="p">(</span><span class="n">scope</span><span class="p">);</span>
      <span class="n">CreateOperators</span><span class="p">();</span>
    <span class="p">}</span>
    <span class="c1">// should run InferShape first.</span>
    <span class="k">for</span> <span class="p">(</span><span class="k">auto</span><span class="o">&amp;</span> <span class="nl">op</span> <span class="p">:</span> <span class="n">runtime_table_</span><span class="p">.</span><span class="n">ops</span><span class="p">())</span> <span class="p">{</span>
      <span class="n">op</span><span class="o">-&gt;</span><span class="n">InferShape</span><span class="p">(</span><span class="n">scope</span><span class="p">);</span>
    <span class="p">}</span>
  <span class="p">}</span>

  <span class="kt">void</span> <span class="n">Run</span><span class="p">(</span><span class="k">const</span> <span class="n">framework</span><span class="o">::</span><span class="n">Scope</span><span class="o">&amp;</span> <span class="n">scope</span><span class="p">,</span>
T
Deploy to GitHub Pages: 735eba29760d8b6f58e0374401a78b64a76c3158  
Travis CI 已提交
499 
           <span class="k">const</span> <span class="n">platform</span><span class="o">::</span><span class="n">Place</span><span class="o">&amp;</span> <span class="n">place</span><span class="p">)</span> <span class="k">const</span> <span class="k">override</span> <span class="p">{</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
500 501 
    <span class="n">PADDLE_ENFORCE</span><span class="p">(</span><span class="n">symbols_ready_</span><span class="p">,</span> <span class="s">&quot;operators and variables should be created first.&quot;</span><span class="p">);</span>
    <span class="k">for</span> <span class="p">(</span><span class="k">auto</span><span class="o">&amp;</span> <span class="nl">op</span> <span class="p">:</span> <span class="n">runtime_table_</span><span class="p">.</span><span class="n">ops</span><span class="p">())</span> <span class="p">{</span>
T
Deploy to GitHub Pages: 735eba29760d8b6f58e0374401a78b64a76c3158  
Travis CI 已提交
502 
      <span class="n">op</span><span class="o">-&gt;</span><span class="n">Run</span><span class="p">(</span><span class="n">scope</span><span class="p">,</span> <span class="n">place</span><span class="p">);</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
503 504 505 506 507 508 
    <span class="p">}</span>
  <span class="p">}</span>

  <span class="kt">void</span> <span class="n">CreateVariables</span><span class="p">(</span><span class="k">const</span> <span class="n">framework</span><span class="o">::</span><span class="n">Scope</span><span class="o">&amp;</span> <span class="n">scope</span><span class="p">);</span>
  <span class="kt">void</span> <span class="nf">CreateOperators</span><span class="p">();</span>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
509 
  <span class="c1">// some other necessary interfaces of NetOp are listed below</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
510 511 512 513 514 515 516 517 518 519 520 521 522 
  <span class="c1">// ...</span>

<span class="k">private</span><span class="o">:</span>
  <span class="n">BlockDesc</span> <span class="n">desc_</span><span class="p">;</span>
  <span class="kt">bool</span> <span class="n">symbols_ready_</span><span class="p">{</span><span class="nb">false</span><span class="p">};</span>
<span class="p">};</span>
</pre></div>
</div>
</div>
<div class="section" id="the-execution-of-blocks">
<span id="the-execution-of-blocks"></span><h2>The Execution of Blocks<a class="headerlink" href="#the-execution-of-blocks" title="永久链接至标题"></a></h2>
<p>Block inherits from OperatorBase, which has a Run method.
Block&#8217;s Run method will run its operators sequentially.</p>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
523 
<p>There is another important interface called <code class="docutils literal"><span class="pre">Eval</span></code>, which takes some arguments called targets and generates a minimal graph which treats targets as the end points and creates a new Block. After <code class="docutils literal"><span class="pre">Run</span></code>, <code class="docutils literal"><span class="pre">Eval</span></code> will get the latest value and return the targets.</p>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
524 525 526 
<p>The definition of Eval is as follows:</p>
<div class="highlight-c++"><div class="highlight"><pre><span></span><span class="c1">// clean a block description by targets using the corresponding dependency graph.</span>
<span class="c1">// return a new BlockDesc with minimal number of operators.</span>
T
Deploy to GitHub Pages: 0a74fed181bea14e6b797e59261631556401d29b  
Travis CI 已提交
527 
<span class="c1">// NOTE: The return type is not a Block but the block&#39;s description so that this can be distributed</span>
T
Deploy to GitHub Pages: 59c48f9831e4a189ea042cd1ebb9be39e98b6d03  
Travis CI 已提交
528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 
<span class="c1">// to a cluster.</span>
<span class="n">BlockDesc</span> <span class="nf">Prune</span><span class="p">(</span><span class="k">const</span> <span class="n">BlockDesc</span><span class="o">&amp;</span> <span class="n">desc</span><span class="p">,</span> <span class="n">vector</span><span class="o">&lt;</span><span class="n">string</span><span class="o">&gt;</span> <span class="n">targets</span><span class="p">);</span>

<span class="kt">void</span> <span class="n">Block</span><span class="o">::</span><span class="n">Eval</span><span class="p">(</span><span class="k">const</span> <span class="n">vector</span><span class="o">&lt;</span><span class="n">string</span><span class="o">&gt;&amp;</span> <span class="n">targets</span><span class="p">,</span>
                 <span class="k">const</span> <span class="n">framework</span><span class="o">::</span><span class="n">Scope</span><span class="o">&amp;</span> <span class="n">scope</span><span class="p">,</span>
                 <span class="k">const</span> <span class="n">platform</span><span class="o">::</span><span class="n">DeviceContext</span><span class="o">&amp;</span> <span class="n">dev_ctx</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">BlockDesc</span> <span class="n">min_desc</span> <span class="o">=</span> <span class="n">Prune</span><span class="p">(</span><span class="n">desc_</span><span class="p">,</span> <span class="n">targets</span><span class="p">);</span>
  <span class="n">Block</span> <span class="nf">min_block</span><span class="p">(</span><span class="n">min_desc</span><span class="p">);</span>
  <span class="n">min_block</span><span class="p">.</span><span class="n">Run</span><span class="p">(</span><span class="n">scope</span><span class="p">,</span> <span class="n">dev_ctx</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
</div>


           </div>
          </div>
          <footer>
  

  <hr/>

  <div role="contentinfo">
    <p>
        &copy; Copyright 2016, PaddlePaddle developers.

    </p>
  </div>
  Built with <a href="http://sphinx-doc.org/">Sphinx</a> using a <a href="https://github.com/snide/sphinx_rtd_theme">theme</a> provided by <a href="https://readthedocs.org">Read the Docs</a>. 

</footer>

        </div>
      </div>

    </section>

  </div>
  


  

    <script type="text/javascript">
        var DOCUMENTATION_OPTIONS = {
            URL_ROOT:'../',
            VERSION:'',
            COLLAPSE_INDEX:false,
            FILE_SUFFIX:'.html',
            HAS_SOURCE:  true,
            SOURCELINK_SUFFIX: ".txt",
        };
    </script>
      <script type="text/javascript" src="../_static/jquery.js"></script>
      <script type="text/javascript" src="../_static/underscore.js"></script>
      <script type="text/javascript" src="../_static/doctools.js"></script>
      <script type="text/javascript" src="../_static/translations.js"></script>
      <script type="text/javascript" src="https://cdn.bootcss.com/mathjax/2.7.0/MathJax.js"></script>
       
  

  
  
    <script type="text/javascript" src="../_static/js/theme.js"></script>
  
  
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>
  <script src="https://cdn.jsdelivr.net/perfect-scrollbar/0.6.14/js/perfect-scrollbar.jquery.min.js"></script>
  <script src="../_static/js/paddle_doc_init.js"></script> 

</body>
</html>