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82 lines
3.8 KiB
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82 lines
3.8 KiB
HTML
4 years ago
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<title>AArch64-Relocations - Using as</title>
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<meta name="description" content="Using as">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="AArch64-Syntax.html#AArch64-Syntax" title="AArch64 Syntax">
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<link rel="prev" href="AArch64_002dRegs.html#AArch64_002dRegs" title="AArch64-Regs">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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This file documents the GNU Assembler "as".
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Copyright (C) 1991-2015 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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--></style>
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</head>
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<body>
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<div class="node">
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<a name="AArch64-Relocations"></a>
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<a name="AArch64_002dRelocations"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="AArch64_002dRegs.html#AArch64_002dRegs">AArch64-Regs</a>,
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Up: <a rel="up" accesskey="u" href="AArch64-Syntax.html#AArch64-Syntax">AArch64 Syntax</a>
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<hr>
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</div>
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<h5 class="subsubsection">9.1.3.3 Relocations</h5>
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<p><a name="index-relocations_002c-AArch64-541"></a><a name="index-AArch64-relocations-542"></a><a name="index-MOVN_002c-MOVZ-and-MOVK-group-relocations_002c-AArch64-543"></a>Relocations for ‘<samp><span class="samp">MOVZ</span></samp>’ and ‘<samp><span class="samp">MOVK</span></samp>’ instructions can be generated
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by prefixing the label with ‘<samp><span class="samp">#:abs_g2:</span></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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<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>
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<p><a name="index-ADRP_002c-ADD_002c-LDR_002fSTR-group-relocations_002c-AArch64-544"></a>Relocations for ‘<samp><span class="samp">ADRP</span></samp>’, and ‘<samp><span class="samp">ADD</span></samp>’, ‘<samp><span class="samp">LDR</span></samp>’ or ‘<samp><span class="samp">STR</span></samp>’
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instructions can be generated by prefixing the label with
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‘<samp><span class="samp">:pg_hi21:</span></samp>’ and ‘<samp><span class="samp">#:lo12:</span></samp>’ respectively.
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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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<pre class="smallexample"> adrp x0, :pg_hi21:foo
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add x0, x0, #:lo12:foo
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</pre>
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<p>Or to load the value of <var>foo</var> into x0:
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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>
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<p>Note that ‘<samp><span class="samp">:pg_hi21:</span></samp>’ is optional.
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<pre class="smallexample"> adrp x0, foo
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</pre>
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<p>is equivalent to
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<pre class="smallexample"> adrp x0, :pg_hi21:foo
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</pre>
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</body></html>
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