68 lines
3.4 KiB
HTML
68 lines
3.4 KiB
HTML
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<title>MIPS FP ABI Selection - 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="MIPS-FP-ABIs.html#MIPS-FP-ABIs" title="MIPS FP ABIs">
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<link rel="prev" href="MIPS-FP-ABI-Variants.html#MIPS-FP-ABI-Variants" title="MIPS FP ABI Variants">
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<link rel="next" href="MIPS-FP-ABI-Compatibility.html#MIPS-FP-ABI-Compatibility" title="MIPS FP ABI Compatibility">
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<!--
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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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</head>
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<body>
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<div class="node">
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<a name="MIPS-FP-ABI-Selection"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="MIPS-FP-ABI-Compatibility.html#MIPS-FP-ABI-Compatibility">MIPS FP ABI Compatibility</a>,
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Previous: <a rel="previous" accesskey="p" href="MIPS-FP-ABI-Variants.html#MIPS-FP-ABI-Variants">MIPS FP ABI Variants</a>,
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Up: <a rel="up" accesskey="u" href="MIPS-FP-ABIs.html#MIPS-FP-ABIs">MIPS FP ABIs</a>
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<hr>
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</div>
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<h5 class="subsubsection">9.27.9.3 Automatic selection of FP ABI</h5>
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<p><a name="index-g_t_0040code_007b_002emodule-fp_003d_0040var_007bnn_007d_007d-directive_002c-MIPS-1595"></a>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, </code><var>n</var> 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, </code><var>n</var> 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>The floating-point ABI is inferred as follows. If ‘<samp><span class="samp">-msoft-float</span></samp>’
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has been used the module will be marked as soft-float. If
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‘<samp><span class="samp">-msingle-float</span></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><span class="samp">-mfpxx</span></samp>’,
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‘<samp><span class="samp">-mfp64</span></samp>’ and ‘<samp><span class="samp">-mno-odd-spreg</span></samp>’.
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</body></html>
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