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Intermediate representation
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<p>An intermediate representation (IR) is the <a href="/facts/Data_structure/yNsNvL1I">data structure</a> or code used internally by a <a href="/facts/Compiler/WNfCDFJe">compiler</a> or <a href="/facts/Virtual_machine/BLevU3sx">virtual machine</a> to represent <a href="/facts/Source_code/o9J6Jv23">source code</a>. An IR is designed to be conducive to further processing, such as <a href="/facts/Compiler_optimization/JXnv4LUd">optimization</a> and <a href="/facts/Program_transformation/lfNb25cd">translation</a>. A "good" IR must be <i>accurate</i> – capable of representing the source code without loss of information – and <i>independent</i> of any particular source or target language. An IR may take one of several forms: an in-memory <a href="/facts/Data_structure/yNsNvL1I">data structure</a>, or a special <a href="/facts/Tuple/BI1HIxL8">tuple</a>- or <a href="/facts/Stack_(abstract_data_type)/bj7l94v1">stack</a>-based <a href="/facts/Bytecode/EPkMFR7M">code</a> readable by the program. In the latter case it is also called an <i>intermediate language</i>. </p><p>A canonical example is found in most modern compilers. For example, the <a href="/facts/CPython/kMhXKEGC">CPython interpreter</a> transforms the linear human-readable text representing a program into an intermediate <a href="/facts/Graph_(data_structure)/b8qcddXa">graph structure</a> that allows <a href="/facts/Flow_analysis/jz2oI6sX">flow analysis</a> and re-arrangement before execution. Use of an intermediate representation such as this allows compiler systems like the <a href="/facts/GNU_Compiler_Collection/t07jh01k">GNU Compiler Collection</a> and <a href="/facts/LLVM/nPmcspQN">LLVM</a> to be used by many different source languages to <a href="/facts/Code_generation_(compiler)/6Ce9gjPs">generate code</a> for many different target <a href="/facts/Instruction_set/8p8vwUeE">architectures</a>. </p>