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163 lines
7.3 KiB
HTML
163 lines
7.3 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>Int Iterators (GNU Compiler Collection (GCC) Internals)</title>
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<meta name="description" content="Int Iterators (GNU Compiler Collection (GCC) Internals)">
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<meta name="keywords" content="Int Iterators (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="Iterators.html#Iterators" rel="up" title="Iterators">
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<link href="Subst-Iterators.html#Subst-Iterators" rel="next" title="Subst Iterators">
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<link href="Code-Iterators.html#Code-Iterators" rel="prev" title="Code Iterators">
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</head>
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<body lang="en">
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<a name="Int-Iterators"></a>
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<div class="header">
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<p>
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Next: <a href="Subst-Iterators.html#Subst-Iterators" accesskey="n" rel="next">Subst Iterators</a>, Previous: <a href="Code-Iterators.html#Code-Iterators" accesskey="p" rel="prev">Code Iterators</a>, Up: <a href="Iterators.html#Iterators" accesskey="u" rel="up">Iterators</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="Int-Iterators-1"></a>
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<h4 class="subsection">17.23.3 Int Iterators</h4>
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<a name="index-int-iterators-in-_002emd-files"></a>
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<a name="index-define_005fint_005fiterator"></a>
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<a name="index-define_005fint_005fattr"></a>
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<p>Int iterators operate in a similar way to code iterators. See <a href="Code-Iterators.html#Code-Iterators">Code Iterators</a>.
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</p>
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<p>The construct:
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</p>
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<div class="smallexample">
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<pre class="smallexample">(define_int_iterator <var>name</var> [(<var>int1</var> "<var>cond1</var>") … (<var>intn</var> "<var>condn</var>")])
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</pre></div>
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<p>defines a pseudo integer constant <var>name</var> that can be instantiated as
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<var>inti</var> if condition <var>condi</var> is true. Each <var>int</var>
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must have the same rtx format. See <a href="RTL-Classes.html#RTL-Classes">RTL Classes</a>. Int iterators can appear
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in only those rtx fields that have ’i’ as the specifier. This means that
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each <var>int</var> has to be a constant defined using define_constant or
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define_c_enum.
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</p>
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<p>As with mode and code iterators, each pattern that uses <var>name</var> will be
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expanded <var>n</var> times, once with all uses of <var>name</var> replaced by
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<var>int1</var>, once with all uses replaced by <var>int2</var>, and so on.
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See <a href="Defining-Mode-Iterators.html#Defining-Mode-Iterators">Defining Mode Iterators</a>.
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</p>
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<p>It is possible to define attributes for ints as well as for codes and modes.
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Attributes are defined using:
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</p>
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<div class="smallexample">
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<pre class="smallexample">(define_int_attr <var>name</var> [(<var>int1</var> "<var>value1</var>") … (<var>intn</var> "<var>valuen</var>")])
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</pre></div>
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<p>Here’s an example of int iterators in action, taken from the ARM port:
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</p>
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<div class="smallexample">
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<pre class="smallexample">(define_int_iterator QABSNEG [UNSPEC_VQABS UNSPEC_VQNEG])
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(define_int_attr absneg [(UNSPEC_VQABS "abs") (UNSPEC_VQNEG "neg")])
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(define_insn "neon_vq<absneg><mode>"
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[(set (match_operand:VDQIW 0 "s_register_operand" "=w")
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(unspec:VDQIW [(match_operand:VDQIW 1 "s_register_operand" "w")
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(match_operand:SI 2 "immediate_operand" "i")]
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QABSNEG))]
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"TARGET_NEON"
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"vq<absneg>.<V_s_elem>\t%<V_reg>0, %<V_reg>1"
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[(set_attr "type" "neon_vqneg_vqabs")]
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)
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</pre></div>
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<p>This is equivalent to:
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</p>
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<div class="smallexample">
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<pre class="smallexample">(define_insn "neon_vqabs<mode>"
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[(set (match_operand:VDQIW 0 "s_register_operand" "=w")
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(unspec:VDQIW [(match_operand:VDQIW 1 "s_register_operand" "w")
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(match_operand:SI 2 "immediate_operand" "i")]
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UNSPEC_VQABS))]
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"TARGET_NEON"
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"vqabs.<V_s_elem>\t%<V_reg>0, %<V_reg>1"
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[(set_attr "type" "neon_vqneg_vqabs")]
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)
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(define_insn "neon_vqneg<mode>"
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[(set (match_operand:VDQIW 0 "s_register_operand" "=w")
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(unspec:VDQIW [(match_operand:VDQIW 1 "s_register_operand" "w")
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(match_operand:SI 2 "immediate_operand" "i")]
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UNSPEC_VQNEG))]
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"TARGET_NEON"
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"vqneg.<V_s_elem>\t%<V_reg>0, %<V_reg>1"
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[(set_attr "type" "neon_vqneg_vqabs")]
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)
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</pre></div>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Subst-Iterators.html#Subst-Iterators" accesskey="n" rel="next">Subst Iterators</a>, Previous: <a href="Code-Iterators.html#Code-Iterators" accesskey="p" rel="prev">Code Iterators</a>, Up: <a href="Iterators.html#Iterators" accesskey="u" rel="up">Iterators</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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