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diff --git a/share/doc/gccint/Using-RTL-SSA.html b/share/doc/gccint/Using-RTL-SSA.html new file mode 100644 index 0000000..c47aee5 --- /dev/null +++ b/share/doc/gccint/Using-RTL-SSA.html @@ -0,0 +1,148 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). 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It is currently local to individual +RTL passes and is not maintained across passes. +</p> +<p>However, in order to allow the RTL SSA information to be preserved across +passes in future, ‘<samp>crtl->ssa</samp>’ points to the current function’s +SSA form (if any). Passes that want to use the RTL SSA form should +first do: +</p> +<div class="smallexample"> +<pre class="smallexample">crtl->ssa = new rtl_ssa::function_info (<var>fn</var>); +</pre></div> + +<p>where <var>fn</var> is the function that the pass is processing. +(Passes that are <code>using namespace rtl_ssa</code> do not need +the ‘<samp>rtl_ssa::</samp>’.) +</p> +<p>Once the pass has finished with the SSA form, it should do the following: +</p> +<div class="smallexample"> +<pre class="smallexample">free_dominance_info (CDI_DOMINATORS); +if (crtl->ssa->perform_pending_updates ()) + cleanup_cfg (0); + +delete crtl->ssa; +crtl->ssa = nullptr; +</pre></div> + +<p>The <code>free_dominance_info</code> call is necessary because +dominance information is not currently maintained between RTL passes. +The next two lines commit any changes to the RTL instructions that +were queued for later; see the comment above the declaration of +<code>perform_pending_updates</code> for details. The final two lines +discard the RTL SSA form and free the associated memory. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="RTL-SSA-Instructions.html#RTL-SSA-Instructions" accesskey="n" rel="next">RTL SSA Instructions</a>, Up: <a href="RTL-SSA.html#RTL-SSA" accesskey="u" rel="up">RTL SSA</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> |