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  20. <title>Tree SSA (GNU Compiler Collection (GCC) Internals)</title>
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  61. <a name="Tree-SSA"></a>
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  63. <p>
  64. Next: <a href="RTL.html#RTL" accesskey="n" rel="next">RTL</a>, Previous: <a href="GIMPLE.html#GIMPLE" accesskey="p" rel="prev">GIMPLE</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
  65. </div>
  66. <hr>
  67. <a name="Analysis-and-Optimization-of-GIMPLE-tuples"></a>
  68. <h2 class="chapter">13 Analysis and Optimization of GIMPLE tuples</h2>
  69. <a name="index-Tree-SSA"></a>
  70. <a name="index-Optimization-infrastructure-for-GIMPLE"></a>
  71. <p>GCC uses three main intermediate languages to represent the program
  72. during compilation: GENERIC, GIMPLE and RTL. GENERIC is a
  73. language-independent representation generated by each front end. It
  74. is used to serve as an interface between the parser and optimizer.
  75. GENERIC is a common representation that is able to represent programs
  76. written in all the languages supported by GCC.
  77. </p>
  78. <p>GIMPLE and RTL are used to optimize the program. GIMPLE is used for
  79. target and language independent optimizations (e.g., inlining,
  80. constant propagation, tail call elimination, redundancy elimination,
  81. etc). Much like GENERIC, GIMPLE is a language independent, tree based
  82. representation. However, it differs from GENERIC in that the GIMPLE
  83. grammar is more restrictive: expressions contain no more than 3
  84. operands (except function calls), it has no control flow structures
  85. and expressions with side effects are only allowed on the right hand
  86. side of assignments. See the chapter describing GENERIC and GIMPLE
  87. for more details.
  88. </p>
  89. <p>This chapter describes the data structures and functions used in the
  90. GIMPLE optimizers (also known as &ldquo;tree optimizers&rdquo; or &ldquo;middle
  91. end&rdquo;). In particular, it focuses on all the macros, data structures,
  92. functions and programming constructs needed to implement optimization
  93. passes for GIMPLE.
  94. </p>
  95. <table class="menu" border="0" cellspacing="0">
  96. <tr><td align="left" valign="top">&bull; <a href="Annotations.html#Annotations" accesskey="1">Annotations</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Attributes for variables.
  97. </td></tr>
  98. <tr><td align="left" valign="top">&bull; <a href="SSA-Operands.html#SSA-Operands" accesskey="2">SSA Operands</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">SSA names referenced by GIMPLE statements.
  99. </td></tr>
  100. <tr><td align="left" valign="top">&bull; <a href="SSA.html#SSA" accesskey="3">SSA</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Static Single Assignment representation.
  101. </td></tr>
  102. <tr><td align="left" valign="top">&bull; <a href="Alias-analysis.html#Alias-analysis" accesskey="4">Alias analysis</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Representing aliased loads and stores.
  103. </td></tr>
  104. <tr><td align="left" valign="top">&bull; <a href="Memory-model.html#Memory-model" accesskey="5">Memory model</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Memory model used by the middle-end.
  105. </td></tr>
  106. </table>
  107. <hr>
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  109. <p>
  110. Next: <a href="RTL.html#RTL" accesskey="n" rel="next">RTL</a>, Previous: <a href="GIMPLE.html#GIMPLE" accesskey="p" rel="prev">GIMPLE</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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