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Copies published by the Free Software Foundation raise funds for GNU development. --> <!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ --> <head> <title>Pass manager (GNU Compiler Collection (GCC) Internals)</title> <meta name="description" content="Pass manager (GNU Compiler Collection (GCC) Internals)"> <meta name="keywords" content="Pass manager (GNU Compiler Collection (GCC) Internals)"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="makeinfo"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <link href="index.html#Top" rel="start" title="Top"> <link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> <link href="Passes.html#Passes" rel="up" title="Passes"> <link href="Tree-SSA-passes.html#Tree-SSA-passes" rel="next" title="Tree SSA passes"> <link href="Gimplification-pass.html#Gimplification-pass" rel="prev" title="Gimplification pass"> <style type="text/css"> <!-- a.summary-letter {text-decoration: none} blockquote.indentedblock {margin-right: 0em} blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} blockquote.smallquotation {font-size: smaller} div.display {margin-left: 3.2em} div.example {margin-left: 3.2em} div.lisp {margin-left: 3.2em} div.smalldisplay {margin-left: 3.2em} div.smallexample {margin-left: 3.2em} div.smalllisp {margin-left: 3.2em} kbd {font-style: oblique} pre.display {font-family: inherit} pre.format {font-family: inherit} pre.menu-comment {font-family: serif} pre.menu-preformatted {font-family: serif} pre.smalldisplay {font-family: inherit; font-size: smaller} pre.smallexample {font-size: smaller} pre.smallformat {font-family: inherit; font-size: smaller} pre.smalllisp {font-size: smaller} span.nolinebreak {white-space: nowrap} span.roman {font-family: initial; font-weight: normal} span.sansserif {font-family: sans-serif; font-weight: normal} ul.no-bullet {list-style: none} --> </style> </head> <body lang="en"> <a name="Pass-manager"></a> <div class="header"> <p> Next: <a href="Tree-SSA-passes.html#Tree-SSA-passes" accesskey="n" rel="next">Tree SSA passes</a>, Previous: <a href="Gimplification-pass.html#Gimplification-pass" accesskey="p" rel="prev">Gimplification pass</a>, Up: <a href="Passes.html#Passes" accesskey="u" rel="up">Passes</a> [<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> </div> <hr> <a name="Pass-manager-1"></a> <h3 class="section">9.3 Pass manager</h3> <p>The pass manager is located in <samp>passes.c</samp>, <samp>tree-optimize.c</samp> and <samp>tree-pass.h</samp>. It processes passes as described in <samp>passes.def</samp>. Its job is to run all of the individual passes in the correct order, and take care of standard bookkeeping that applies to every pass. </p> <p>The theory of operation is that each pass defines a structure that represents everything we need to know about that pass—when it should be run, how it should be run, what intermediate language form or on-the-side data structures it needs. We register the pass to be run in some particular order, and the pass manager arranges for everything to happen in the correct order. </p> <p>The actuality doesn’t completely live up to the theory at present. Command-line switches and <code>timevar_id_t</code> enumerations must still be defined elsewhere. The pass manager validates constraints but does not attempt to (re-)generate data structures or lower intermediate language form based on the requirements of the next pass. Nevertheless, what is present is useful, and a far sight better than nothing at all. </p> <p>Each pass should have a unique name. Each pass may have its own dump file (for GCC debugging purposes). Passes with a name starting with a star do not dump anything. Sometimes passes are supposed to share a dump file / option name. To still give these unique names, you can use a prefix that is delimited by a space from the part that is used for the dump file / option name. E.g. When the pass name is "ud dce", the name used for dump file/options is "dce". </p> <p>TODO: describe the global variables set up by the pass manager, and a brief description of how a new pass should use it. I need to look at what info RTL passes use first<small class="enddots">...</small> </p> <hr> <div class="header"> <p> Next: <a href="Tree-SSA-passes.html#Tree-SSA-passes" accesskey="n" rel="next">Tree SSA passes</a>, Previous: <a href="Gimplification-pass.html#Gimplification-pass" accesskey="p" rel="prev">Gimplification pass</a>, Up: <a href="Passes.html#Passes" accesskey="u" rel="up">Passes</a> [<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> </div> </body> </html>