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diff --git a/share/doc/gcc/AArch64-Function-Attributes.html b/share/doc/gcc/AArch64-Function-Attributes.html new file mode 100644 index 0000000..ab10ff8 --- /dev/null +++ b/share/doc/gcc/AArch64-Function-Attributes.html @@ -0,0 +1,265 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- This file documents the use of the GNU compilers. + +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>Using the GNU Compiler Collection (GCC): AArch64 Function Attributes</title> + +<meta name="description" content="Using the GNU Compiler Collection (GCC): AArch64 Function Attributes"> +<meta name="keywords" content="Using the GNU Compiler Collection (GCC): AArch64 Function Attributes"> +<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="Indices.html#Indices" rel="index" title="Indices"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Function-Attributes.html#Function-Attributes" rel="up" title="Function Attributes"> +<link href="AMD-GCN-Function-Attributes.html#AMD-GCN-Function-Attributes" rel="next" title="AMD GCN Function Attributes"> +<link href="Common-Function-Attributes.html#Common-Function-Attributes" rel="previous" title="Common Function Attributes"> +<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_US" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="AArch64-Function-Attributes"></a> +<div class="header"> +<p> +Next: <a href="AMD-GCN-Function-Attributes.html#AMD-GCN-Function-Attributes" accesskey="n" rel="next">AMD GCN Function Attributes</a>, Previous: <a href="Common-Function-Attributes.html#Common-Function-Attributes" accesskey="p" rel="previous">Common Function Attributes</a>, Up: <a href="Function-Attributes.html#Function-Attributes" accesskey="u" rel="up">Function Attributes</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="AArch64-Function-Attributes-1"></a> +<h4 class="subsection">6.33.2 AArch64 Function Attributes</h4> + +<p>The following target-specific function attributes are available for the +AArch64 target. For the most part, these options mirror the behavior of +similar command-line options (see <a href="AArch64-Options.html#AArch64-Options">AArch64 Options</a>), but on a +per-function basis. +</p> +<dl compact="compact"> +<dd><a name="index-general_002dregs_002donly-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>general-regs-only</code></dt> +<dd><p>Indicates that no floating-point or Advanced SIMD registers should be +used when generating code for this function. If the function explicitly +uses floating-point code, then the compiler gives an error. This is +the same behavior as that of the command-line option +<samp>-mgeneral-regs-only</samp>. +</p> +<a name="index-fix_002dcortex_002da53_002d835769-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>fix-cortex-a53-835769</code></dt> +<dd><p>Indicates that the workaround for the Cortex-A53 erratum 835769 should be +applied to this function. To explicitly disable the workaround for this +function specify the negated form: <code>no-fix-cortex-a53-835769</code>. +This corresponds to the behavior of the command line options +<samp>-mfix-cortex-a53-835769</samp> and <samp>-mno-fix-cortex-a53-835769</samp>. +</p> +<a name="index-cmodel_003d-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>cmodel=</code></dt> +<dd><p>Indicates that code should be generated for a particular code model for +this function. The behavior and permissible arguments are the same as +for the command line option <samp>-mcmodel=</samp>. +</p> +<a name="index-strict_002dalign-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>strict-align</code></dt> +<dt><code>no-strict-align</code></dt> +<dd><p><code>strict-align</code> indicates that the compiler should not assume that unaligned +memory references are handled by the system. To allow the compiler to assume +that aligned memory references are handled by the system, the inverse attribute +<code>no-strict-align</code> can be specified. The behavior is same as for the +command-line option <samp>-mstrict-align</samp> and <samp>-mno-strict-align</samp>. +</p> +<a name="index-omit_002dleaf_002dframe_002dpointer-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>omit-leaf-frame-pointer</code></dt> +<dd><p>Indicates that the frame pointer should be omitted for a leaf function call. +To keep the frame pointer, the inverse attribute +<code>no-omit-leaf-frame-pointer</code> can be specified. These attributes have +the same behavior as the command-line options <samp>-momit-leaf-frame-pointer</samp> +and <samp>-mno-omit-leaf-frame-pointer</samp>. +</p> +<a name="index-tls_002ddialect_003d-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>tls-dialect=</code></dt> +<dd><p>Specifies the TLS dialect to use for this function. The behavior and +permissible arguments are the same as for the command-line option +<samp>-mtls-dialect=</samp>. +</p> +<a name="index-arch_003d-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>arch=</code></dt> +<dd><p>Specifies the architecture version and architectural extensions to use +for this function. The behavior and permissible arguments are the same as +for the <samp>-march=</samp> command-line option. +</p> +<a name="index-tune_003d-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>tune=</code></dt> +<dd><p>Specifies the core for which to tune the performance of this function. +The behavior and permissible arguments are the same as for the <samp>-mtune=</samp> +command-line option. +</p> +<a name="index-cpu_003d-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>cpu=</code></dt> +<dd><p>Specifies the core for which to tune the performance of this function and also +whose architectural features to use. The behavior and valid arguments are the +same as for the <samp>-mcpu=</samp> command-line option. +</p> +<a name="index-sign_002dreturn_002daddress-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>sign-return-address</code></dt> +<dd><p>Select the function scope on which return address signing will be applied. The +behavior and permissible arguments are the same as for the command-line option +<samp>-msign-return-address=</samp>. The default value is <code>none</code>. This +attribute is deprecated. The <code>branch-protection</code> attribute should +be used instead. +</p> +<a name="index-branch_002dprotection-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>branch-protection</code></dt> +<dd><p>Select the function scope on which branch protection will be applied. The +behavior and permissible arguments are the same as for the command-line option +<samp>-mbranch-protection=</samp>. The default value is <code>none</code>. +</p> +<a name="index-outline_002datomics-function-attribute_002c-AArch64"></a> +</dd> +<dt><code>outline-atomics</code></dt> +<dd><p>Enable or disable calls to out-of-line helpers to implement atomic operations. +This corresponds to the behavior of the command line options +<samp>-moutline-atomics</samp> and <samp>-mno-outline-atomics</samp>. +</p> +</dd> +</dl> + +<p>The above target attributes can be specified as follows: +</p> +<div class="smallexample"> +<pre class="smallexample">__attribute__((target("<var>attr-string</var>"))) +int +f (int a) +{ + return a + 5; +} +</pre></div> + +<p>where <code><var>attr-string</var></code> is one of the attribute strings specified above. +</p> +<p>Additionally, the architectural extension string may be specified on its +own. This can be used to turn on and off particular architectural extensions +without having to specify a particular architecture version or core. Example: +</p> +<div class="smallexample"> +<pre class="smallexample">__attribute__((target("+crc+nocrypto"))) +int +foo (int a) +{ + return a + 5; +} +</pre></div> + +<p>In this example <code>target("+crc+nocrypto")</code> enables the <code>crc</code> +extension and disables the <code>crypto</code> extension for the function <code>foo</code> +without modifying an existing <samp>-march=</samp> or <samp>-mcpu</samp> option. +</p> +<p>Multiple target function attributes can be specified by separating them with +a comma. For example: +</p><div class="smallexample"> +<pre class="smallexample">__attribute__((target("arch=armv8-a+crc+crypto,tune=cortex-a53"))) +int +foo (int a) +{ + return a + 5; +} +</pre></div> + +<p>is valid and compiles function <code>foo</code> for ARMv8-A with <code>crc</code> +and <code>crypto</code> extensions and tunes it for <code>cortex-a53</code>. +</p> +<a name="Inlining-rules"></a> +<h4 class="subsubsection">6.33.2.1 Inlining rules</h4> +<p>Specifying target attributes on individual functions or performing link-time +optimization across translation units compiled with different target options +can affect function inlining rules: +</p> +<p>In particular, a caller function can inline a callee function only if the +architectural features available to the callee are a subset of the features +available to the caller. +For example: A function <code>foo</code> compiled with <samp>-march=armv8-a+crc</samp>, +or tagged with the equivalent <code>arch=armv8-a+crc</code> attribute, +can inline a function <code>bar</code> compiled with <samp>-march=armv8-a+nocrc</samp> +because the all the architectural features that function <code>bar</code> requires +are available to function <code>foo</code>. Conversely, function <code>bar</code> cannot +inline function <code>foo</code>. +</p> +<p>Additionally inlining a function compiled with <samp>-mstrict-align</samp> into a +function compiled without <code>-mstrict-align</code> is not allowed. +However, inlining a function compiled without <samp>-mstrict-align</samp> into a +function compiled with <samp>-mstrict-align</samp> is allowed. +</p> +<p>Note that CPU tuning options and attributes such as the <samp>-mcpu=</samp>, +<samp>-mtune=</samp> do not inhibit inlining unless the CPU specified by the +<samp>-mcpu=</samp> option or the <code>cpu=</code> attribute conflicts with the +architectural feature rules specified above. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="AMD-GCN-Function-Attributes.html#AMD-GCN-Function-Attributes" accesskey="n" rel="next">AMD GCN Function Attributes</a>, Previous: <a href="Common-Function-Attributes.html#Common-Function-Attributes" accesskey="p" rel="previous">Common Function Attributes</a>, Up: <a href="Function-Attributes.html#Function-Attributes" accesskey="u" rel="up">Function Attributes</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |