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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gccint/Parameterized-Names.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
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diff --git a/share/doc/gccint/Parameterized-Names.html b/share/doc/gccint/Parameterized-Names.html new file mode 100644 index 0000000..17b4ce4 --- /dev/null +++ b/share/doc/gccint/Parameterized-Names.html @@ -0,0 +1,197 @@ +<!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). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>GNU Compiler Collection (GCC) Internals: Parameterized Names</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Parameterized Names"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Parameterized Names"> +<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="Iterators.html#Iterators" rel="up" title="Iterators"> +<link href="Target-Macros.html#Target-Macros" rel="next" title="Target Macros"> +<link href="Subst-Iterators.html#Subst-Iterators" rel="previous" title="Subst Iterators"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +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.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Parameterized-Names"></a> +<div class="header"> +<p> +Previous: <a href="Subst-Iterators.html#Subst-Iterators" accesskey="p" rel="previous">Subst 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> +</div> +<hr> +<a name="Parameterized-Names-1"></a> +<h4 class="subsection">17.23.5 Parameterized Names</h4> +<a name="index-_0040-in-instruction-pattern-names"></a> +<p>Ports sometimes need to apply iterators using C++ code, in order to +get the code or RTL pattern for a specific instruction. For example, +suppose we have the ‘<samp>neon_vq<absneg><mode></samp>’ pattern given above: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_int_iterator QABSNEG [UNSPEC_VQABS UNSPEC_VQNEG]) + +(define_int_attr absneg [(UNSPEC_VQABS "abs") (UNSPEC_VQNEG "neg")]) + +(define_insn "neon_vq<absneg><mode>" + [(set (match_operand:VDQIW 0 "s_register_operand" "=w") + (unspec:VDQIW [(match_operand:VDQIW 1 "s_register_operand" "w") + (match_operand:SI 2 "immediate_operand" "i")] + QABSNEG))] + … +) +</pre></div> + +<p>A port might need to generate this pattern for a variable +‘<samp>QABSNEG</samp>’ value and a variable ‘<samp>VDQIW</samp>’ mode. There are two +ways of doing this. The first is to build the rtx for the pattern +directly from C++ code; this is a valid technique and avoids any risk +of combinatorial explosion. The second is to prefix the instruction +name with the special character ‘<samp>@</samp>’, which tells GCC to generate +the four additional functions below. In each case, <var>name</var> is the +name of the instruction without the leading ‘<samp>@</samp>’ character, +without the ‘<samp><…></samp>’ placeholders, and with any underscore +before a ‘<samp><…></samp>’ placeholder removed if keeping it would +lead to a double or trailing underscore. +</p> +<dl compact="compact"> +<dt>‘<samp>insn_code maybe_code_for_<var>name</var> (<var>i1</var>, <var>i2</var>, …)</samp>’</dt> +<dd><p>See whether replacing the first ‘<samp><…></samp>’ placeholder with +iterator value <var>i1</var>, the second with iterator value <var>i2</var>, and +so on, gives a valid instruction. Return its code if so, otherwise +return <code>CODE_FOR_nothing</code>. +</p> +</dd> +<dt>‘<samp>insn_code code_for_<var>name</var> (<var>i1</var>, <var>i2</var>, …)</samp>’</dt> +<dd><p>Same, but abort the compiler if the requested instruction does not exist. +</p> +</dd> +<dt>‘<samp>rtx maybe_gen_<var>name</var> (<var>i1</var>, <var>i2</var>, …, <var>op0</var>, <var>op1</var>, …)</samp>’</dt> +<dd><p>Check for a valid instruction in the same way as +<code>maybe_code_for_<var>name</var></code>. If the instruction exists, +generate an instance of it using the operand values given by <var>op0</var>, +<var>op1</var>, and so on, otherwise return null. +</p> +</dd> +<dt>‘<samp>rtx gen_<var>name</var> (<var>i1</var>, <var>i2</var>, …, <var>op0</var>, <var>op1</var>, …)</samp>’</dt> +<dd><p>Same, but abort the compiler if the requested instruction does not exist, +or if the instruction generator invoked the <code>FAIL</code> macro. +</p></dd> +</dl> + +<p>For example, changing the pattern above to: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_insn "@neon_vq<absneg><mode>" + [(set (match_operand:VDQIW 0 "s_register_operand" "=w") + (unspec:VDQIW [(match_operand:VDQIW 1 "s_register_operand" "w") + (match_operand:SI 2 "immediate_operand" "i")] + QABSNEG))] + … +) +</pre></div> + +<p>would define the same patterns as before, but in addition would generate +the four functions below: +</p> +<div class="smallexample"> +<pre class="smallexample">insn_code maybe_code_for_neon_vq (int, machine_mode); +insn_code code_for_neon_vq (int, machine_mode); +rtx maybe_gen_neon_vq (int, machine_mode, rtx, rtx, rtx); +rtx gen_neon_vq (int, machine_mode, rtx, rtx, rtx); +</pre></div> + +<p>Calling ‘<samp>code_for_neon_vq (UNSPEC_VQABS, V8QImode)</samp>’ +would then give <code>CODE_FOR_neon_vqabsv8qi</code>. +</p> +<p>It is possible to have multiple ‘<samp>@</samp>’ patterns with the same +name and same types of iterator. For example: +</p> +<div class="smallexample"> +<pre class="smallexample">(define_insn "@some_arithmetic_op<mode>" + [(set (match_operand:INTEGER_MODES 0 "register_operand") …)] + … +) + +(define_insn "@some_arithmetic_op<mode>" + [(set (match_operand:FLOAT_MODES 0 "register_operand") …)] + … +) +</pre></div> + +<p>would produce a single set of functions that handles both +<code>INTEGER_MODES</code> and <code>FLOAT_MODES</code>. +</p> +<p>It is also possible for these ‘<samp>@</samp>’ patterns to have different +numbers of operands from each other. For example, patterns with +a binary rtl code might take three operands (one output and two inputs) +while patterns with a ternary rtl code might take four operands (one +output and three inputs). This combination would produce separate +‘<samp>maybe_gen_<var>name</var></samp>’ and ‘<samp>gen_<var>name</var></samp>’ functions for +each operand count, but it would still produce a single +‘<samp>maybe_code_for_<var>name</var></samp>’ and a single ‘<samp>code_for_<var>name</var></samp>’. +</p> + +<hr> +<div class="header"> +<p> +Previous: <a href="Subst-Iterators.html#Subst-Iterators" accesskey="p" rel="previous">Subst 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> +</div> + + + +</body> +</html> |