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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/Allocation-Order.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Change-Id: I7303388733328cd98ab9aa3c30236db67f2e9e9c
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diff --git a/share/doc/gccint/Allocation-Order.html b/share/doc/gccint/Allocation-Order.html new file mode 100644 index 0000000..8c770eb --- /dev/null +++ b/share/doc/gccint/Allocation-Order.html @@ -0,0 +1,147 @@ +<!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: Allocation Order</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Allocation Order"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Allocation Order"> +<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="Registers.html#Registers" rel="up" title="Registers"> +<link href="Values-in-Registers.html#Values-in-Registers" rel="next" title="Values in Registers"> +<link href="Register-Basics.html#Register-Basics" rel="previous" title="Register Basics"> +<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="Allocation-Order"></a> +<div class="header"> +<p> +Next: <a href="Values-in-Registers.html#Values-in-Registers" accesskey="n" rel="next">Values in Registers</a>, Previous: <a href="Register-Basics.html#Register-Basics" accesskey="p" rel="previous">Register Basics</a>, Up: <a href="Registers.html#Registers" accesskey="u" rel="up">Registers</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="Order-of-Allocation-of-Registers"></a> +<h4 class="subsection">18.7.2 Order of Allocation of Registers</h4> +<a name="index-order-of-register-allocation"></a> +<a name="index-register-allocation-order"></a> + +<p>Registers are allocated in order. +</p> +<dl> +<dt><a name="index-REG_005fALLOC_005fORDER"></a>Macro: <strong>REG_ALLOC_ORDER</strong></dt> +<dd><p>If defined, an initializer for a vector of integers, containing the +numbers of hard registers in the order in which GCC should prefer +to use them (from most preferred to least). +</p> +<p>If this macro is not defined, registers are used lowest numbered first +(all else being equal). +</p> +<p>One use of this macro is on machines where the highest numbered +registers must always be saved and the save-multiple-registers +instruction supports only sequences of consecutive registers. On such +machines, define <code>REG_ALLOC_ORDER</code> to be an initializer that lists +the highest numbered allocable register first. +</p></dd></dl> + +<dl> +<dt><a name="index-ADJUST_005fREG_005fALLOC_005fORDER"></a>Macro: <strong>ADJUST_REG_ALLOC_ORDER</strong></dt> +<dd><p>A C statement (sans semicolon) to choose the order in which to allocate +hard registers for pseudo-registers local to a basic block. +</p> +<p>Store the desired register order in the array <code>reg_alloc_order</code>. +Element 0 should be the register to allocate first; element 1, the next +register; and so on. +</p> +<p>The macro body should not assume anything about the contents of +<code>reg_alloc_order</code> before execution of the macro. +</p> +<p>On most machines, it is not necessary to define this macro. +</p></dd></dl> + +<dl> +<dt><a name="index-HONOR_005fREG_005fALLOC_005fORDER"></a>Macro: <strong>HONOR_REG_ALLOC_ORDER</strong></dt> +<dd><p>Normally, IRA tries to estimate the costs for saving a register in the +prologue and restoring it in the epilogue. This discourages it from +using call-saved registers. If a machine wants to ensure that IRA +allocates registers in the order given by REG_ALLOC_ORDER even if some +call-saved registers appear earlier than call-used ones, then define this +macro as a C expression to nonzero. Default is 0. +</p></dd></dl> + +<dl> +<dt><a name="index-IRA_005fHARD_005fREGNO_005fADD_005fCOST_005fMULTIPLIER"></a>Macro: <strong>IRA_HARD_REGNO_ADD_COST_MULTIPLIER</strong> <em>(<var>regno</var>)</em></dt> +<dd><p>In some case register allocation order is not enough for the +Integrated Register Allocator (<acronym>IRA</acronym>) to generate a good code. +If this macro is defined, it should return a floating point value +based on <var>regno</var>. The cost of using <var>regno</var> for a pseudo will +be increased by approximately the pseudo’s usage frequency times the +value returned by this macro. Not defining this macro is equivalent +to having it always return <code>0.0</code>. +</p> +<p>On most machines, it is not necessary to define this macro. +</p></dd></dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Values-in-Registers.html#Values-in-Registers" accesskey="n" rel="next">Values in Registers</a>, Previous: <a href="Register-Basics.html#Register-Basics" accesskey="p" rel="previous">Register Basics</a>, Up: <a href="Registers.html#Registers" accesskey="u" rel="up">Registers</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> |