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92 lines
4.3 KiB
HTML
92 lines
4.3 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>MIPS FP ABI Selection (Using as)</title>
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<meta name="description" content="MIPS FP ABI Selection (Using as)">
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<meta name="keywords" content="MIPS FP ABI Selection (Using as)">
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<meta name="resource-type" content="document">
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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="MIPS-FP-ABIs.html#MIPS-FP-ABIs" rel="up" title="MIPS FP ABIs">
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<link href="MIPS-FP-ABI-Compatibility.html#MIPS-FP-ABI-Compatibility" rel="next" title="MIPS FP ABI Compatibility">
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<link href="MIPS-FP-ABI-Variants.html#MIPS-FP-ABI-Variants" rel="prev" title="MIPS FP ABI Variants">
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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="MIPS-FP-ABI-Selection"></a>
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<div class="header">
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<p>
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Next: <a href="MIPS-FP-ABI-Compatibility.html#MIPS-FP-ABI-Compatibility" accesskey="n" rel="next">MIPS FP ABI Compatibility</a>, Previous: <a href="MIPS-FP-ABI-Variants.html#MIPS-FP-ABI-Variants" accesskey="p" rel="prev">MIPS FP ABI Variants</a>, Up: <a href="MIPS-FP-ABIs.html#MIPS-FP-ABIs" accesskey="u" rel="up">MIPS FP ABIs</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="Automatic-selection-of-FP-ABI"></a>
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<h4 class="subsubsection">9.26.9.3 Automatic selection of FP ABI</h4>
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<a name="index-_002emodule-fp_003dnn-directive_002c-MIPS"></a>
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<p>In order to simplify and add safety to the process of selecting the
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correct floating-point ABI, the assembler will automatically infer the
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correct <code>.gnu_attribute 4, <var>n</var></code> directive based on command-line
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options and <code>.module</code> overrides. Where an explicit
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<code>.gnu_attribute 4, <var>n</var></code> directive has been seen then a warning
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will be raised if it does not match an inferred setting.
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</p>
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<p>The floating-point ABI is inferred as follows. If ‘<samp>-msoft-float</samp>’
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has been used the module will be marked as soft-float. If
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‘<samp>-msingle-float</samp>’ has been used then the module will be marked as
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single-precision. The remaining ABIs are then selected based
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on the FP register width. Double-precision is selected if the width
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of GP and FP registers match and the special double-precision variants
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for 32-bit ABIs are then selected depending on ‘<samp>-mfpxx</samp>’,
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‘<samp>-mfp64</samp>’ and ‘<samp>-mno-odd-spreg</samp>’.
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</p>
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</body>
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</html>
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