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121 lines
4.8 KiB
HTML
121 lines
4.8 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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<!-- This file documents the GNU Assembler "as".
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Copyright (C) 1991-2019 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
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled "GNU Free Documentation License".
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-->
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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>AArch64-Relocations (Using as)</title>
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<meta name="description" content="AArch64-Relocations (Using as)">
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<meta name="keywords" content="AArch64-Relocations (Using as)">
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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="AS-Index.html#AS-Index" rel="index" title="AS Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="AArch64-Syntax.html#AArch64-Syntax" rel="up" title="AArch64 Syntax">
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<link href="AArch64-Floating-Point.html#AArch64-Floating-Point" rel="next" title="AArch64 Floating Point">
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<link href="AArch64_002dRegs.html#AArch64_002dRegs" rel="prev" title="AArch64-Regs">
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-->
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</style>
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</head>
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<body lang="en">
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<a name="AArch64_002dRelocations"></a>
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<div class="header">
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<p>
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Previous: <a href="AArch64_002dRegs.html#AArch64_002dRegs" accesskey="p" rel="prev">AArch64-Regs</a>, Up: <a href="AArch64-Syntax.html#AArch64-Syntax" accesskey="u" rel="up">AArch64 Syntax</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Relocations"></a>
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<h4 class="subsubsection">9.1.3.3 Relocations</h4>
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<a name="index-relocations_002c-AArch64"></a>
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<a name="index-AArch64-relocations"></a>
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<a name="index-MOVN_002c-MOVZ-and-MOVK-group-relocations_002c-AArch64"></a>
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<p>Relocations for ‘<samp>MOVZ</samp>’ and ‘<samp>MOVK</samp>’ instructions can be generated
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by prefixing the label with ‘<samp>#:abs_g2:</samp>’ etc.
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For example to load the 48-bit absolute address of <var>foo</var> into x0:
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</p>
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<div class="smallexample">
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<pre class="smallexample"> movz x0, #:abs_g2:foo // bits 32-47, overflow check
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movk x0, #:abs_g1_nc:foo // bits 16-31, no overflow check
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movk x0, #:abs_g0_nc:foo // bits 0-15, no overflow check
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</pre></div>
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<a name="index-ADRP_002c-ADD_002c-LDR_002fSTR-group-relocations_002c-AArch64"></a>
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<p>Relocations for ‘<samp>ADRP</samp>’, and ‘<samp>ADD</samp>’, ‘<samp>LDR</samp>’ or ‘<samp>STR</samp>’
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instructions can be generated by prefixing the label with
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‘<samp>:pg_hi21:</samp>’ and ‘<samp>#:lo12:</samp>’ respectively.
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</p>
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<p>For example to use 33-bit (+/-4GB) pc-relative addressing to
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load the address of <var>foo</var> into x0:
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</p>
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<div class="smallexample">
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<pre class="smallexample"> adrp x0, :pg_hi21:foo
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add x0, x0, #:lo12:foo
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</pre></div>
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<p>Or to load the value of <var>foo</var> into x0:
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</p>
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<div class="smallexample">
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<pre class="smallexample"> adrp x0, :pg_hi21:foo
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ldr x0, [x0, #:lo12:foo]
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</pre></div>
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<p>Note that ‘<samp>:pg_hi21:</samp>’ is optional.
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</p>
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<div class="smallexample">
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<pre class="smallexample"> adrp x0, foo
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</pre></div>
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<p>is equivalent to
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</p>
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<div class="smallexample">
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<pre class="smallexample"> adrp x0, :pg_hi21:foo
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</pre></div>
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</body>
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</html>
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