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105 lines
4.9 KiB
HTML
105 lines
4.9 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2018 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Define Subst Pattern Matching (GNU Compiler Collection (GCC) Internals)</title>
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<meta name="description" content="Define Subst Pattern Matching (GNU Compiler Collection (GCC) Internals)">
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<meta name="keywords" content="Define Subst Pattern Matching (GNU Compiler Collection (GCC) Internals)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Define-Subst.html#Define-Subst" rel="up" title="Define Subst">
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<link href="Define-Subst-Output-Template.html#Define-Subst-Output-Template" rel="next" title="Define Subst Output Template">
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<link href="Define-Subst-Example.html#Define-Subst-Example" rel="prev" title="Define Subst Example">
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</style>
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</head>
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<body lang="en">
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<a name="Define-Subst-Pattern-Matching"></a>
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<div class="header">
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<p>
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Next: <a href="Define-Subst-Output-Template.html#Define-Subst-Output-Template" accesskey="n" rel="next">Define Subst Output Template</a>, Previous: <a href="Define-Subst-Example.html#Define-Subst-Example" accesskey="p" rel="prev">Define Subst Example</a>, Up: <a href="Define-Subst.html#Define-Subst" accesskey="u" rel="up">Define Subst</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>
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</div>
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<hr>
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<a name="Pattern-Matching-in-define_005fsubst"></a>
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<h4 class="subsection">17.21.2 Pattern Matching in <code>define_subst</code></h4>
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<a name="index-define_005fsubst-2"></a>
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<p>All expressions, allowed in <code>define_insn</code> or <code>define_expand</code>,
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are allowed in the input-template of <code>define_subst</code>, except
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<code>match_par_dup</code>, <code>match_scratch</code>, <code>match_parallel</code>. The
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meanings of expressions in the input-template were changed:
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</p>
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<p><code>match_operand</code> matches any expression (possibly, a subtree in
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RTL-template), if modes of the <code>match_operand</code> and this expression
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are the same, or mode of the <code>match_operand</code> is <code>VOIDmode</code>, or
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this expression is <code>match_dup</code>, <code>match_op_dup</code>. If the
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expression is <code>match_operand</code> too, and predicate of
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<code>match_operand</code> from the input pattern is not empty, then the
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predicates are compared. That can be used for more accurate filtering
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of accepted RTL-templates.
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</p>
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<p><code>match_operator</code> matches common operators (like <code>plus</code>,
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<code>minus</code>), <code>unspec</code>, <code>unspec_volatile</code> operators and
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<code>match_operator</code>s from the original pattern if the modes match and
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<code>match_operator</code> from the input pattern has the same number of
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operands as the operator from the original pattern.
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</p>
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</body>
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</html>
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