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980 lines
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HTML
980 lines
41 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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<!-- Copyright (C) 1988-2018 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 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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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>PowerPC SPE Options (Using the GNU Compiler Collection (GCC))</title>
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<meta name="description" content="PowerPC SPE Options (Using the GNU Compiler Collection (GCC))">
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<meta name="keywords" content="PowerPC SPE Options (Using the GNU Compiler Collection (GCC))">
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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="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Submodel-Options.html#Submodel-Options" rel="up" title="Submodel Options">
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<link href="RISC_002dV-Options.html#RISC_002dV-Options" rel="next" title="RISC-V Options">
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<link href="PowerPC-Options.html#PowerPC-Options" rel="prev" title="PowerPC Options">
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<style type="text/css">
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a.summary-letter {text-decoration: none}
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blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
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blockquote.smallquotation {font-size: smaller}
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div.display {margin-left: 3.2em}
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div.example {margin-left: 3.2em}
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div.lisp {margin-left: 3.2em}
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div.smalllisp {margin-left: 3.2em}
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kbd {font-style: oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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span.nolinebreak {white-space: nowrap}
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span.roman {font-family: initial; font-weight: normal}
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ul.no-bullet {list-style: none}
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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="PowerPC-SPE-Options"></a>
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<div class="header">
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<p>
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Next: <a href="RISC_002dV-Options.html#RISC_002dV-Options" accesskey="n" rel="next">RISC-V Options</a>, Previous: <a href="PowerPC-Options.html#PowerPC-Options" accesskey="p" rel="prev">PowerPC Options</a>, Up: <a href="Submodel-Options.html#Submodel-Options" accesskey="u" rel="up">Submodel Options</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>
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</div>
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<hr>
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<a name="PowerPC-SPE-Options-1"></a>
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<h4 class="subsection">3.18.37 PowerPC SPE Options</h4>
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<a name="index-PowerPC-SPE-options"></a>
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<p>These ‘<samp>-m</samp>’ options are defined for PowerPC SPE:
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</p><dl compact="compact">
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<dt><code>-mmfcrf</code></dt>
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<dt><code>-mno-mfcrf</code></dt>
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<dt><code>-mpopcntb</code></dt>
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<dt><code>-mno-popcntb</code></dt>
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<dd><a name="index-mmfcrf"></a>
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<a name="index-mno_002dmfcrf"></a>
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<a name="index-mpopcntb"></a>
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<a name="index-mno_002dpopcntb"></a>
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<p>You use these options to specify which instructions are available on the
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processor you are using. The default value of these options is
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determined when configuring GCC. Specifying the
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<samp>-mcpu=<var>cpu_type</var></samp> overrides the specification of these
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options. We recommend you use the <samp>-mcpu=<var>cpu_type</var></samp> option
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rather than the options listed above.
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</p>
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<p>The <samp>-mmfcrf</samp> option allows GCC to generate the move from
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condition register field instruction implemented on the POWER4
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processor and other processors that support the PowerPC V2.01
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architecture.
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The <samp>-mpopcntb</samp> option allows GCC to generate the popcount and
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double-precision FP reciprocal estimate instruction implemented on the
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POWER5 processor and other processors that support the PowerPC V2.02
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architecture.
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</p>
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</dd>
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<dt><code>-mcpu=<var>cpu_type</var></code></dt>
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<dd><a name="index-mcpu-8"></a>
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<p>Set architecture type, register usage, and
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instruction scheduling parameters for machine type <var>cpu_type</var>.
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Supported values for <var>cpu_type</var> are ‘<samp>8540</samp>’, ‘<samp>8548</samp>’,
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and ‘<samp>native</samp>’.
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</p>
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<p><samp>-mcpu=powerpc</samp> specifies pure 32-bit PowerPC (either
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endian), with an appropriate, generic processor model assumed for
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scheduling purposes.
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</p>
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<p>Specifying ‘<samp>native</samp>’ as cpu type detects and selects the
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architecture option that corresponds to the host processor of the
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system performing the compilation.
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<samp>-mcpu=native</samp> has no effect if GCC does not recognize the
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processor.
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</p>
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<p>The other options specify a specific processor. Code generated under
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those options runs best on that processor, and may not run at all on
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others.
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</p>
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<p>The <samp>-mcpu</samp> options automatically enable or disable the
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following options:
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</p>
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<div class="smallexample">
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<pre class="smallexample">-mhard-float -mmfcrf -mmultiple
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-mpopcntb -mpopcntd
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-msingle-float -mdouble-float
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-mfloat128
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</pre></div>
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<p>The particular options set for any particular CPU varies between
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compiler versions, depending on what setting seems to produce optimal
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code for that CPU; it doesn’t necessarily reflect the actual hardware’s
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capabilities. If you wish to set an individual option to a particular
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value, you may specify it after the <samp>-mcpu</samp> option, like
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<samp>-mcpu=8548</samp>.
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</p>
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</dd>
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<dt><code>-mtune=<var>cpu_type</var></code></dt>
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<dd><a name="index-mtune-10"></a>
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<p>Set the instruction scheduling parameters for machine type
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<var>cpu_type</var>, but do not set the architecture type or register usage,
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as <samp>-mcpu=<var>cpu_type</var></samp> does. The same
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values for <var>cpu_type</var> are used for <samp>-mtune</samp> as for
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<samp>-mcpu</samp>. If both are specified, the code generated uses the
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architecture and registers set by <samp>-mcpu</samp>, but the
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scheduling parameters set by <samp>-mtune</samp>.
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</p>
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</dd>
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<dt><code>-msecure-plt</code></dt>
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<dd><a name="index-msecure_002dplt"></a>
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<p>Generate code that allows <code>ld</code> and <code>ld.so</code>
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to build executables and shared
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libraries with non-executable <code>.plt</code> and <code>.got</code> sections.
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This is a PowerPC
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32-bit SYSV ABI option.
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</p>
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</dd>
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<dt><code>-mbss-plt</code></dt>
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<dd><a name="index-mbss_002dplt"></a>
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<p>Generate code that uses a BSS <code>.plt</code> section that <code>ld.so</code>
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fills in, and
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requires <code>.plt</code> and <code>.got</code>
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sections that are both writable and executable.
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This is a PowerPC 32-bit SYSV ABI option.
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</p>
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</dd>
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<dt><code>-misel</code></dt>
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<dt><code>-mno-isel</code></dt>
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<dd><a name="index-misel"></a>
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<a name="index-mno_002disel"></a>
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<p>This switch enables or disables the generation of ISEL instructions.
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</p>
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</dd>
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<dt><code>-misel=<var>yes/no</var></code></dt>
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<dd><p>This switch has been deprecated. Use <samp>-misel</samp> and
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<samp>-mno-isel</samp> instead.
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</p>
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</dd>
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<dt><code>-mspe</code></dt>
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<dt><code>-mno-spe</code></dt>
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<dd><a name="index-mspe"></a>
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<a name="index-mno_002dspe"></a>
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<p>This switch enables or disables the generation of SPE simd
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instructions.
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</p>
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</dd>
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<dt><code>-mspe=<var>yes/no</var></code></dt>
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<dd><p>This option has been deprecated. Use <samp>-mspe</samp> and
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<samp>-mno-spe</samp> instead.
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</p>
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</dd>
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<dt><code>-mfloat128</code></dt>
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<dt><code>-mno-float128</code></dt>
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<dd><a name="index-mfloat128"></a>
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<a name="index-mno_002dfloat128"></a>
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<p>Enable/disable the <var>__float128</var> keyword for IEEE 128-bit floating point
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and use either software emulation for IEEE 128-bit floating point or
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hardware instructions.
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</p>
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</dd>
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<dt><code>-mfloat-gprs=<var>yes/single/double/no</var></code></dt>
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<dt><code>-mfloat-gprs</code></dt>
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<dd><a name="index-mfloat_002dgprs"></a>
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<p>This switch enables or disables the generation of floating-point
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operations on the general-purpose registers for architectures that
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support it.
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</p>
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<p>The argument ‘<samp>yes</samp>’ or ‘<samp>single</samp>’ enables the use of
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single-precision floating-point operations.
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</p>
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<p>The argument ‘<samp>double</samp>’ enables the use of single and
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double-precision floating-point operations.
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</p>
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<p>The argument ‘<samp>no</samp>’ disables floating-point operations on the
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general-purpose registers.
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</p>
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<p>This option is currently only available on the MPC854x.
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</p>
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</dd>
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<dt><code>-mfull-toc</code></dt>
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<dt><code>-mno-fp-in-toc</code></dt>
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<dt><code>-mno-sum-in-toc</code></dt>
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<dt><code>-mminimal-toc</code></dt>
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<dd><a name="index-mfull_002dtoc"></a>
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<a name="index-mno_002dfp_002din_002dtoc"></a>
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<a name="index-mno_002dsum_002din_002dtoc"></a>
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<a name="index-mminimal_002dtoc"></a>
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<p>Modify generation of the TOC (Table Of Contents), which is created for
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every executable file. The <samp>-mfull-toc</samp> option is selected by
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default. In that case, GCC allocates at least one TOC entry for
|
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each unique non-automatic variable reference in your program. GCC
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also places floating-point constants in the TOC. However, only
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16,384 entries are available in the TOC.
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</p>
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<p>If you receive a linker error message that saying you have overflowed
|
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the available TOC space, you can reduce the amount of TOC space used
|
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with the <samp>-mno-fp-in-toc</samp> and <samp>-mno-sum-in-toc</samp> options.
|
||
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<samp>-mno-fp-in-toc</samp> prevents GCC from putting floating-point
|
||
|
|
constants in the TOC and <samp>-mno-sum-in-toc</samp> forces GCC to
|
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|
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generate code to calculate the sum of an address and a constant at
|
||
|
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run time instead of putting that sum into the TOC. You may specify one
|
||
|
|
or both of these options. Each causes GCC to produce very slightly
|
||
|
|
slower and larger code at the expense of conserving TOC space.
|
||
|
|
</p>
|
||
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<p>If you still run out of space in the TOC even when you specify both of
|
||
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these options, specify <samp>-mminimal-toc</samp> instead. This option causes
|
||
|
|
GCC to make only one TOC entry for every file. When you specify this
|
||
|
|
option, GCC produces code that is slower and larger but which
|
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uses extremely little TOC space. You may wish to use this option
|
||
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only on files that contain less frequently-executed code.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-maix32</code></dt>
|
||
|
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<dd><a name="index-maix32"></a>
|
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<p>Disables the 64-bit ABI. GCC defaults to <samp>-maix32</samp>.
|
||
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</p>
|
||
|
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</dd>
|
||
|
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<dt><code>-mxl-compat</code></dt>
|
||
|
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<dt><code>-mno-xl-compat</code></dt>
|
||
|
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<dd><a name="index-mxl_002dcompat"></a>
|
||
|
|
<a name="index-mno_002dxl_002dcompat"></a>
|
||
|
|
<p>Produce code that conforms more closely to IBM XL compiler semantics
|
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|
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when using AIX-compatible ABI. Pass floating-point arguments to
|
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|
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prototyped functions beyond the register save area (RSA) on the stack
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in addition to argument FPRs. Do not assume that most significant
|
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|
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double in 128-bit long double value is properly rounded when comparing
|
||
|
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values and converting to double. Use XL symbol names for long double
|
||
|
|
support routines.
|
||
|
|
</p>
|
||
|
|
<p>The AIX calling convention was extended but not initially documented to
|
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|
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handle an obscure K&R C case of calling a function that takes the
|
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address of its arguments with fewer arguments than declared. IBM XL
|
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compilers access floating-point arguments that do not fit in the
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RSA from the stack when a subroutine is compiled without
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optimization. Because always storing floating-point arguments on the
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stack is inefficient and rarely needed, this option is not enabled by
|
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default and only is necessary when calling subroutines compiled by IBM
|
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XL compilers without optimization.
|
||
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</p>
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||
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</dd>
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<dt><code>-malign-natural</code></dt>
|
||
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<dt><code>-malign-power</code></dt>
|
||
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<dd><a name="index-malign_002dnatural"></a>
|
||
|
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<a name="index-malign_002dpower"></a>
|
||
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<p>On AIX, 32-bit Darwin, and 64-bit PowerPC GNU/Linux, the option
|
||
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<samp>-malign-natural</samp> overrides the ABI-defined alignment of larger
|
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types, such as floating-point doubles, on their natural size-based boundary.
|
||
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The option <samp>-malign-power</samp> instructs GCC to follow the ABI-specified
|
||
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alignment rules. GCC defaults to the standard alignment defined in the ABI.
|
||
|
|
</p>
|
||
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<p>On 64-bit Darwin, natural alignment is the default, and <samp>-malign-power</samp>
|
||
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is not supported.
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||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msoft-float</code></dt>
|
||
|
|
<dt><code>-mhard-float</code></dt>
|
||
|
|
<dd><a name="index-msoft_002dfloat-8"></a>
|
||
|
|
<a name="index-mhard_002dfloat-4"></a>
|
||
|
|
<p>Generate code that does not use (uses) the floating-point register set.
|
||
|
|
Software floating-point emulation is provided if you use the
|
||
|
|
<samp>-msoft-float</samp> option, and pass the option to GCC when linking.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msingle-float</code></dt>
|
||
|
|
<dt><code>-mdouble-float</code></dt>
|
||
|
|
<dd><a name="index-msingle_002dfloat-1"></a>
|
||
|
|
<a name="index-mdouble_002dfloat-1"></a>
|
||
|
|
<p>Generate code for single- or double-precision floating-point operations.
|
||
|
|
<samp>-mdouble-float</samp> implies <samp>-msingle-float</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mmultiple</code></dt>
|
||
|
|
<dt><code>-mno-multiple</code></dt>
|
||
|
|
<dd><a name="index-mmultiple"></a>
|
||
|
|
<a name="index-mno_002dmultiple"></a>
|
||
|
|
<p>Generate code that uses (does not use) the load multiple word
|
||
|
|
instructions and the store multiple word instructions. These
|
||
|
|
instructions are generated by default on POWER systems, and not
|
||
|
|
generated on PowerPC systems. Do not use <samp>-mmultiple</samp> on little-endian
|
||
|
|
PowerPC systems, since those instructions do not work when the
|
||
|
|
processor is in little-endian mode. The exceptions are PPC740 and
|
||
|
|
PPC750 which permit these instructions in little-endian mode.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mupdate</code></dt>
|
||
|
|
<dt><code>-mno-update</code></dt>
|
||
|
|
<dd><a name="index-mupdate"></a>
|
||
|
|
<a name="index-mno_002dupdate"></a>
|
||
|
|
<p>Generate code that uses (does not use) the load or store instructions
|
||
|
|
that update the base register to the address of the calculated memory
|
||
|
|
location. These instructions are generated by default. If you use
|
||
|
|
<samp>-mno-update</samp>, there is a small window between the time that the
|
||
|
|
stack pointer is updated and the address of the previous frame is
|
||
|
|
stored, which means code that walks the stack frame across interrupts or
|
||
|
|
signals may get corrupted data.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mavoid-indexed-addresses</code></dt>
|
||
|
|
<dt><code>-mno-avoid-indexed-addresses</code></dt>
|
||
|
|
<dd><a name="index-mavoid_002dindexed_002daddresses"></a>
|
||
|
|
<a name="index-mno_002davoid_002dindexed_002daddresses"></a>
|
||
|
|
<p>Generate code that tries to avoid (not avoid) the use of indexed load
|
||
|
|
or store instructions. These instructions can incur a performance
|
||
|
|
penalty on Power6 processors in certain situations, such as when
|
||
|
|
stepping through large arrays that cross a 16M boundary. This option
|
||
|
|
is enabled by default when targeting Power6 and disabled otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mfused-madd</code></dt>
|
||
|
|
<dt><code>-mno-fused-madd</code></dt>
|
||
|
|
<dd><a name="index-mfused_002dmadd-2"></a>
|
||
|
|
<a name="index-mno_002dfused_002dmadd-2"></a>
|
||
|
|
<p>Generate code that uses (does not use) the floating-point multiply and
|
||
|
|
accumulate instructions. These instructions are generated by default
|
||
|
|
if hardware floating point is used. The machine-dependent
|
||
|
|
<samp>-mfused-madd</samp> option is now mapped to the machine-independent
|
||
|
|
<samp>-ffp-contract=fast</samp> option, and <samp>-mno-fused-madd</samp> is
|
||
|
|
mapped to <samp>-ffp-contract=off</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mno-strict-align</code></dt>
|
||
|
|
<dt><code>-mstrict-align</code></dt>
|
||
|
|
<dd><a name="index-mno_002dstrict_002dalign-1"></a>
|
||
|
|
<a name="index-mstrict_002dalign-2"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems do not (do) assume that
|
||
|
|
unaligned memory references are handled by the system.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mrelocatable</code></dt>
|
||
|
|
<dt><code>-mno-relocatable</code></dt>
|
||
|
|
<dd><a name="index-mrelocatable"></a>
|
||
|
|
<a name="index-mno_002drelocatable"></a>
|
||
|
|
<p>Generate code that allows (does not allow) a static executable to be
|
||
|
|
relocated to a different address at run time. A simple embedded
|
||
|
|
PowerPC system loader should relocate the entire contents of
|
||
|
|
<code>.got2</code> and 4-byte locations listed in the <code>.fixup</code> section,
|
||
|
|
a table of 32-bit addresses generated by this option. For this to
|
||
|
|
work, all objects linked together must be compiled with
|
||
|
|
<samp>-mrelocatable</samp> or <samp>-mrelocatable-lib</samp>.
|
||
|
|
<samp>-mrelocatable</samp> code aligns the stack to an 8-byte boundary.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mrelocatable-lib</code></dt>
|
||
|
|
<dt><code>-mno-relocatable-lib</code></dt>
|
||
|
|
<dd><a name="index-mrelocatable_002dlib"></a>
|
||
|
|
<a name="index-mno_002drelocatable_002dlib"></a>
|
||
|
|
<p>Like <samp>-mrelocatable</samp>, <samp>-mrelocatable-lib</samp> generates a
|
||
|
|
<code>.fixup</code> section to allow static executables to be relocated at
|
||
|
|
run time, but <samp>-mrelocatable-lib</samp> does not use the smaller stack
|
||
|
|
alignment of <samp>-mrelocatable</samp>. Objects compiled with
|
||
|
|
<samp>-mrelocatable-lib</samp> may be linked with objects compiled with
|
||
|
|
any combination of the <samp>-mrelocatable</samp> options.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mno-toc</code></dt>
|
||
|
|
<dt><code>-mtoc</code></dt>
|
||
|
|
<dd><a name="index-mno_002dtoc"></a>
|
||
|
|
<a name="index-mtoc"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems do not (do) assume that
|
||
|
|
register 2 contains a pointer to a global area pointing to the addresses
|
||
|
|
used in the program.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mlittle</code></dt>
|
||
|
|
<dt><code>-mlittle-endian</code></dt>
|
||
|
|
<dd><a name="index-mlittle"></a>
|
||
|
|
<a name="index-mlittle_002dendian-8"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems compile code for the
|
||
|
|
processor in little-endian mode. The <samp>-mlittle-endian</samp> option is
|
||
|
|
the same as <samp>-mlittle</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mbig</code></dt>
|
||
|
|
<dt><code>-mbig-endian</code></dt>
|
||
|
|
<dd><a name="index-mbig"></a>
|
||
|
|
<a name="index-mbig_002dendian-8"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems compile code for the
|
||
|
|
processor in big-endian mode. The <samp>-mbig-endian</samp> option is
|
||
|
|
the same as <samp>-mbig</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mdynamic-no-pic</code></dt>
|
||
|
|
<dd><a name="index-mdynamic_002dno_002dpic"></a>
|
||
|
|
<p>On Darwin and Mac OS X systems, compile code so that it is not
|
||
|
|
relocatable, but that its external references are relocatable. The
|
||
|
|
resulting code is suitable for applications, but not shared
|
||
|
|
libraries.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msingle-pic-base</code></dt>
|
||
|
|
<dd><a name="index-msingle_002dpic_002dbase-1"></a>
|
||
|
|
<p>Treat the register used for PIC addressing as read-only, rather than
|
||
|
|
loading it in the prologue for each function. The runtime system is
|
||
|
|
responsible for initializing this register with an appropriate value
|
||
|
|
before execution begins.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mprioritize-restricted-insns=<var>priority</var></code></dt>
|
||
|
|
<dd><a name="index-mprioritize_002drestricted_002dinsns"></a>
|
||
|
|
<p>This option controls the priority that is assigned to
|
||
|
|
dispatch-slot restricted instructions during the second scheduling
|
||
|
|
pass. The argument <var>priority</var> takes the value ‘<samp>0</samp>’, ‘<samp>1</samp>’,
|
||
|
|
or ‘<samp>2</samp>’ to assign no, highest, or second-highest (respectively)
|
||
|
|
priority to dispatch-slot restricted
|
||
|
|
instructions.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msched-costly-dep=<var>dependence_type</var></code></dt>
|
||
|
|
<dd><a name="index-msched_002dcostly_002ddep"></a>
|
||
|
|
<p>This option controls which dependences are considered costly
|
||
|
|
by the target during instruction scheduling. The argument
|
||
|
|
<var>dependence_type</var> takes one of the following values:
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dt>‘<samp>no</samp>’</dt>
|
||
|
|
<dd><p>No dependence is costly.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>all</samp>’</dt>
|
||
|
|
<dd><p>All dependences are costly.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>true_store_to_load</samp>’</dt>
|
||
|
|
<dd><p>A true dependence from store to load is costly.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>store_to_load</samp>’</dt>
|
||
|
|
<dd><p>Any dependence from store to load is costly.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><var>number</var></dt>
|
||
|
|
<dd><p>Any dependence for which the latency is greater than or equal to
|
||
|
|
<var>number</var> is costly.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
</dd>
|
||
|
|
<dt><code>-minsert-sched-nops=<var>scheme</var></code></dt>
|
||
|
|
<dd><a name="index-minsert_002dsched_002dnops"></a>
|
||
|
|
<p>This option controls which NOP insertion scheme is used during
|
||
|
|
the second scheduling pass. The argument <var>scheme</var> takes one of the
|
||
|
|
following values:
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dt>‘<samp>no</samp>’</dt>
|
||
|
|
<dd><p>Don’t insert NOPs.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>pad</samp>’</dt>
|
||
|
|
<dd><p>Pad with NOPs any dispatch group that has vacant issue slots,
|
||
|
|
according to the scheduler’s grouping.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>regroup_exact</samp>’</dt>
|
||
|
|
<dd><p>Insert NOPs to force costly dependent insns into
|
||
|
|
separate groups. Insert exactly as many NOPs as needed to force an insn
|
||
|
|
to a new group, according to the estimated processor grouping.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><var>number</var></dt>
|
||
|
|
<dd><p>Insert NOPs to force costly dependent insns into
|
||
|
|
separate groups. Insert <var>number</var> NOPs to force an insn to a new group.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcall-sysv</code></dt>
|
||
|
|
<dd><a name="index-mcall_002dsysv"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems compile code using calling
|
||
|
|
conventions that adhere to the March 1995 draft of the System V
|
||
|
|
Application Binary Interface, PowerPC processor supplement. This is the
|
||
|
|
default unless you configured GCC using ‘<samp>powerpc-*-eabiaix</samp>’.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcall-sysv-eabi</code></dt>
|
||
|
|
<dt><code>-mcall-eabi</code></dt>
|
||
|
|
<dd><a name="index-mcall_002dsysv_002deabi"></a>
|
||
|
|
<a name="index-mcall_002deabi"></a>
|
||
|
|
<p>Specify both <samp>-mcall-sysv</samp> and <samp>-meabi</samp> options.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcall-sysv-noeabi</code></dt>
|
||
|
|
<dd><a name="index-mcall_002dsysv_002dnoeabi"></a>
|
||
|
|
<p>Specify both <samp>-mcall-sysv</samp> and <samp>-mno-eabi</samp> options.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcall-aixdesc</code></dt>
|
||
|
|
<dd><a name="index-m"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems compile code for the AIX
|
||
|
|
operating system.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcall-linux</code></dt>
|
||
|
|
<dd><a name="index-mcall_002dlinux"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems compile code for the
|
||
|
|
Linux-based GNU system.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcall-freebsd</code></dt>
|
||
|
|
<dd><a name="index-mcall_002dfreebsd"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems compile code for the
|
||
|
|
FreeBSD operating system.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcall-netbsd</code></dt>
|
||
|
|
<dd><a name="index-mcall_002dnetbsd"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems compile code for the
|
||
|
|
NetBSD operating system.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcall-openbsd</code></dt>
|
||
|
|
<dd><a name="index-mcall_002dnetbsd-1"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems compile code for the
|
||
|
|
OpenBSD operating system.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-maix-struct-return</code></dt>
|
||
|
|
<dd><a name="index-maix_002dstruct_002dreturn"></a>
|
||
|
|
<p>Return all structures in memory (as specified by the AIX ABI).
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msvr4-struct-return</code></dt>
|
||
|
|
<dd><a name="index-msvr4_002dstruct_002dreturn"></a>
|
||
|
|
<p>Return structures smaller than 8 bytes in registers (as specified by the
|
||
|
|
SVR4 ABI).
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mabi=<var>abi-type</var></code></dt>
|
||
|
|
<dd><a name="index-mabi-2"></a>
|
||
|
|
<p>Extend the current ABI with a particular extension, or remove such extension.
|
||
|
|
Valid values are ‘<samp>altivec</samp>’, ‘<samp>no-altivec</samp>’, ‘<samp>spe</samp>’,
|
||
|
|
‘<samp>no-spe</samp>’, ‘<samp>ibmlongdouble</samp>’, ‘<samp>ieeelongdouble</samp>’,
|
||
|
|
‘<samp>elfv1</samp>’, ‘<samp>elfv2</samp>’.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mabi=spe</code></dt>
|
||
|
|
<dd><a name="index-mabi_003dspe"></a>
|
||
|
|
<p>Extend the current ABI with SPE ABI extensions. This does not change
|
||
|
|
the default ABI, instead it adds the SPE ABI extensions to the current
|
||
|
|
ABI.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mabi=no-spe</code></dt>
|
||
|
|
<dd><a name="index-mabi_003dno_002dspe"></a>
|
||
|
|
<p>Disable Book-E SPE ABI extensions for the current ABI.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mabi=ibmlongdouble</code></dt>
|
||
|
|
<dd><a name="index-mabi_003dibmlongdouble"></a>
|
||
|
|
<p>Change the current ABI to use IBM extended-precision long double.
|
||
|
|
This is not likely to work if your system defaults to using IEEE
|
||
|
|
extended-precision long double. If you change the long double type
|
||
|
|
from IEEE extended-precision, the compiler will issue a warning unless
|
||
|
|
you use the <samp>-Wno-psabi</samp> option. Requires <samp>-mlong-double-128</samp>
|
||
|
|
to be enabled.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mabi=ieeelongdouble</code></dt>
|
||
|
|
<dd><a name="index-mabi_003dieeelongdouble"></a>
|
||
|
|
<p>Change the current ABI to use IEEE extended-precision long double.
|
||
|
|
This is not likely to work if your system defaults to using IBM
|
||
|
|
extended-precision long double. If you change the long double type
|
||
|
|
from IBM extended-precision, the compiler will issue a warning unless
|
||
|
|
you use the <samp>-Wno-psabi</samp> option. Requires <samp>-mlong-double-128</samp>
|
||
|
|
to be enabled.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mabi=elfv1</code></dt>
|
||
|
|
<dd><a name="index-mabi_003delfv1"></a>
|
||
|
|
<p>Change the current ABI to use the ELFv1 ABI.
|
||
|
|
This is the default ABI for big-endian PowerPC 64-bit Linux.
|
||
|
|
Overriding the default ABI requires special system support and is
|
||
|
|
likely to fail in spectacular ways.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mabi=elfv2</code></dt>
|
||
|
|
<dd><a name="index-mabi_003delfv2"></a>
|
||
|
|
<p>Change the current ABI to use the ELFv2 ABI.
|
||
|
|
This is the default ABI for little-endian PowerPC 64-bit Linux.
|
||
|
|
Overriding the default ABI requires special system support and is
|
||
|
|
likely to fail in spectacular ways.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mgnu-attribute</code></dt>
|
||
|
|
<dt><code>-mno-gnu-attribute</code></dt>
|
||
|
|
<dd><a name="index-mgnu_002dattribute"></a>
|
||
|
|
<a name="index-mno_002dgnu_002dattribute"></a>
|
||
|
|
<p>Emit .gnu_attribute assembly directives to set tag/value pairs in a
|
||
|
|
.gnu.attributes section that specify ABI variations in function
|
||
|
|
parameters or return values.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mprototype</code></dt>
|
||
|
|
<dt><code>-mno-prototype</code></dt>
|
||
|
|
<dd><a name="index-mprototype"></a>
|
||
|
|
<a name="index-mno_002dprototype"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems assume that all calls to
|
||
|
|
variable argument functions are properly prototyped. Otherwise, the
|
||
|
|
compiler must insert an instruction before every non-prototyped call to
|
||
|
|
set or clear bit 6 of the condition code register (<code>CR</code>) to
|
||
|
|
indicate whether floating-point values are passed in the floating-point
|
||
|
|
registers in case the function takes variable arguments. With
|
||
|
|
<samp>-mprototype</samp>, only calls to prototyped variable argument functions
|
||
|
|
set or clear the bit.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msim</code></dt>
|
||
|
|
<dd><a name="index-msim-7"></a>
|
||
|
|
<p>On embedded PowerPC systems, assume that the startup module is called
|
||
|
|
<samp>sim-crt0.o</samp> and that the standard C libraries are <samp>libsim.a</samp> and
|
||
|
|
<samp>libc.a</samp>. This is the default for ‘<samp>powerpc-*-eabisim</samp>’
|
||
|
|
configurations.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mmvme</code></dt>
|
||
|
|
<dd><a name="index-mmvme"></a>
|
||
|
|
<p>On embedded PowerPC systems, assume that the startup module is called
|
||
|
|
<samp>crt0.o</samp> and the standard C libraries are <samp>libmvme.a</samp> and
|
||
|
|
<samp>libc.a</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mads</code></dt>
|
||
|
|
<dd><a name="index-mads"></a>
|
||
|
|
<p>On embedded PowerPC systems, assume that the startup module is called
|
||
|
|
<samp>crt0.o</samp> and the standard C libraries are <samp>libads.a</samp> and
|
||
|
|
<samp>libc.a</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-myellowknife</code></dt>
|
||
|
|
<dd><a name="index-myellowknife"></a>
|
||
|
|
<p>On embedded PowerPC systems, assume that the startup module is called
|
||
|
|
<samp>crt0.o</samp> and the standard C libraries are <samp>libyk.a</samp> and
|
||
|
|
<samp>libc.a</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mvxworks</code></dt>
|
||
|
|
<dd><a name="index-mvxworks"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems, specify that you are
|
||
|
|
compiling for a VxWorks system.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-memb</code></dt>
|
||
|
|
<dd><a name="index-memb"></a>
|
||
|
|
<p>On embedded PowerPC systems, set the <code>PPC_EMB</code> bit in the ELF flags
|
||
|
|
header to indicate that ‘<samp>eabi</samp>’ extended relocations are used.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-meabi</code></dt>
|
||
|
|
<dt><code>-mno-eabi</code></dt>
|
||
|
|
<dd><a name="index-meabi"></a>
|
||
|
|
<a name="index-mno_002deabi"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems do (do not) adhere to the
|
||
|
|
Embedded Applications Binary Interface (EABI), which is a set of
|
||
|
|
modifications to the System V.4 specifications. Selecting <samp>-meabi</samp>
|
||
|
|
means that the stack is aligned to an 8-byte boundary, a function
|
||
|
|
<code>__eabi</code> is called from <code>main</code> to set up the EABI
|
||
|
|
environment, and the <samp>-msdata</samp> option can use both <code>r2</code> and
|
||
|
|
<code>r13</code> to point to two separate small data areas. Selecting
|
||
|
|
<samp>-mno-eabi</samp> means that the stack is aligned to a 16-byte boundary,
|
||
|
|
no EABI initialization function is called from <code>main</code>, and the
|
||
|
|
<samp>-msdata</samp> option only uses <code>r13</code> to point to a single
|
||
|
|
small data area. The <samp>-meabi</samp> option is on by default if you
|
||
|
|
configured GCC using one of the ‘<samp>powerpc*-*-eabi*</samp>’ options.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msdata=eabi</code></dt>
|
||
|
|
<dd><a name="index-msdata_003deabi"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems, put small initialized
|
||
|
|
<code>const</code> global and static data in the <code>.sdata2</code> section, which
|
||
|
|
is pointed to by register <code>r2</code>. Put small initialized
|
||
|
|
non-<code>const</code> global and static data in the <code>.sdata</code> section,
|
||
|
|
which is pointed to by register <code>r13</code>. Put small uninitialized
|
||
|
|
global and static data in the <code>.sbss</code> section, which is adjacent to
|
||
|
|
the <code>.sdata</code> section. The <samp>-msdata=eabi</samp> option is
|
||
|
|
incompatible with the <samp>-mrelocatable</samp> option. The
|
||
|
|
<samp>-msdata=eabi</samp> option also sets the <samp>-memb</samp> option.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msdata=sysv</code></dt>
|
||
|
|
<dd><a name="index-msdata_003dsysv"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems, put small global and static
|
||
|
|
data in the <code>.sdata</code> section, which is pointed to by register
|
||
|
|
<code>r13</code>. Put small uninitialized global and static data in the
|
||
|
|
<code>.sbss</code> section, which is adjacent to the <code>.sdata</code> section.
|
||
|
|
The <samp>-msdata=sysv</samp> option is incompatible with the
|
||
|
|
<samp>-mrelocatable</samp> option.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msdata=default</code></dt>
|
||
|
|
<dt><code>-msdata</code></dt>
|
||
|
|
<dd><a name="index-msdata_003ddefault-1"></a>
|
||
|
|
<a name="index-msdata-1"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems, if <samp>-meabi</samp> is used,
|
||
|
|
compile code the same as <samp>-msdata=eabi</samp>, otherwise compile code the
|
||
|
|
same as <samp>-msdata=sysv</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msdata=data</code></dt>
|
||
|
|
<dd><a name="index-msdata_003ddata"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems, put small global
|
||
|
|
data in the <code>.sdata</code> section. Put small uninitialized global
|
||
|
|
data in the <code>.sbss</code> section. Do not use register <code>r13</code>
|
||
|
|
to address small data however. This is the default behavior unless
|
||
|
|
other <samp>-msdata</samp> options are used.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msdata=none</code></dt>
|
||
|
|
<dt><code>-mno-sdata</code></dt>
|
||
|
|
<dd><a name="index-msdata_003dnone-2"></a>
|
||
|
|
<a name="index-mno_002dsdata-2"></a>
|
||
|
|
<p>On embedded PowerPC systems, put all initialized global and static data
|
||
|
|
in the <code>.data</code> section, and all uninitialized data in the
|
||
|
|
<code>.bss</code> section.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mblock-move-inline-limit=<var>num</var></code></dt>
|
||
|
|
<dd><a name="index-mblock_002dmove_002dinline_002dlimit"></a>
|
||
|
|
<p>Inline all block moves (such as calls to <code>memcpy</code> or structure
|
||
|
|
copies) less than or equal to <var>num</var> bytes. The minimum value for
|
||
|
|
<var>num</var> is 32 bytes on 32-bit targets and 64 bytes on 64-bit
|
||
|
|
targets. The default value is target-specific.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-G <var>num</var></code></dt>
|
||
|
|
<dd><a name="index-G-4"></a>
|
||
|
|
<a name="index-smaller-data-references-_0028PowerPC_0029"></a>
|
||
|
|
<a name="index-_002esdata_002f_002esdata2-references-_0028PowerPC_0029"></a>
|
||
|
|
<p>On embedded PowerPC systems, put global and static items less than or
|
||
|
|
equal to <var>num</var> bytes into the small data or BSS sections instead of
|
||
|
|
the normal data or BSS section. By default, <var>num</var> is 8. The
|
||
|
|
<samp>-G <var>num</var></samp> switch is also passed to the linker.
|
||
|
|
All modules should be compiled with the same <samp>-G <var>num</var></samp> value.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mregnames</code></dt>
|
||
|
|
<dt><code>-mno-regnames</code></dt>
|
||
|
|
<dd><a name="index-mregnames"></a>
|
||
|
|
<a name="index-mno_002dregnames"></a>
|
||
|
|
<p>On System V.4 and embedded PowerPC systems do (do not) emit register
|
||
|
|
names in the assembly language output using symbolic forms.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mlongcall</code></dt>
|
||
|
|
<dt><code>-mno-longcall</code></dt>
|
||
|
|
<dd><a name="index-mlongcall"></a>
|
||
|
|
<a name="index-mno_002dlongcall"></a>
|
||
|
|
<p>By default assume that all calls are far away so that a longer and more
|
||
|
|
expensive calling sequence is required. This is required for calls
|
||
|
|
farther than 32 megabytes (33,554,432 bytes) from the current location.
|
||
|
|
A short call is generated if the compiler knows
|
||
|
|
the call cannot be that far away. This setting can be overridden by
|
||
|
|
the <code>shortcall</code> function attribute, or by <code>#pragma
|
||
|
|
longcall(0)</code>.
|
||
|
|
</p>
|
||
|
|
<p>Some linkers are capable of detecting out-of-range calls and generating
|
||
|
|
glue code on the fly. On these systems, long calls are unnecessary and
|
||
|
|
generate slower code. As of this writing, the AIX linker can do this,
|
||
|
|
as can the GNU linker for PowerPC/64. It is planned to add this feature
|
||
|
|
to the GNU linker for 32-bit PowerPC systems as well.
|
||
|
|
</p>
|
||
|
|
<p>In the future, GCC may ignore all longcall specifications
|
||
|
|
when the linker is known to generate glue.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mtls-markers</code></dt>
|
||
|
|
<dt><code>-mno-tls-markers</code></dt>
|
||
|
|
<dd><a name="index-mtls_002dmarkers"></a>
|
||
|
|
<a name="index-mno_002dtls_002dmarkers"></a>
|
||
|
|
<p>Mark (do not mark) calls to <code>__tls_get_addr</code> with a relocation
|
||
|
|
specifying the function argument. The relocation allows the linker to
|
||
|
|
reliably associate function call with argument setup instructions for
|
||
|
|
TLS optimization, which in turn allows GCC to better schedule the
|
||
|
|
sequence.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mrecip</code></dt>
|
||
|
|
<dt><code>-mno-recip</code></dt>
|
||
|
|
<dd><a name="index-mrecip"></a>
|
||
|
|
<p>This option enables use of the reciprocal estimate and
|
||
|
|
reciprocal square root estimate instructions with additional
|
||
|
|
Newton-Raphson steps to increase precision instead of doing a divide or
|
||
|
|
square root and divide for floating-point arguments. You should use
|
||
|
|
the <samp>-ffast-math</samp> option when using <samp>-mrecip</samp> (or at
|
||
|
|
least <samp>-funsafe-math-optimizations</samp>,
|
||
|
|
<samp>-ffinite-math-only</samp>, <samp>-freciprocal-math</samp> and
|
||
|
|
<samp>-fno-trapping-math</samp>). Note that while the throughput of the
|
||
|
|
sequence is generally higher than the throughput of the non-reciprocal
|
||
|
|
instruction, the precision of the sequence can be decreased by up to 2
|
||
|
|
ulp (i.e. the inverse of 1.0 equals 0.99999994) for reciprocal square
|
||
|
|
roots.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mrecip=<var>opt</var></code></dt>
|
||
|
|
<dd><a name="index-mrecip_003dopt"></a>
|
||
|
|
<p>This option controls which reciprocal estimate instructions
|
||
|
|
may be used. <var>opt</var> is a comma-separated list of options, which may
|
||
|
|
be preceded by a <code>!</code> to invert the option:
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dt>‘<samp>all</samp>’</dt>
|
||
|
|
<dd><p>Enable all estimate instructions.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>default</samp>’</dt>
|
||
|
|
<dd><p>Enable the default instructions, equivalent to <samp>-mrecip</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>none</samp>’</dt>
|
||
|
|
<dd><p>Disable all estimate instructions, equivalent to <samp>-mno-recip</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>div</samp>’</dt>
|
||
|
|
<dd><p>Enable the reciprocal approximation instructions for both
|
||
|
|
single and double precision.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>divf</samp>’</dt>
|
||
|
|
<dd><p>Enable the single-precision reciprocal approximation instructions.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>divd</samp>’</dt>
|
||
|
|
<dd><p>Enable the double-precision reciprocal approximation instructions.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>rsqrt</samp>’</dt>
|
||
|
|
<dd><p>Enable the reciprocal square root approximation instructions for both
|
||
|
|
single and double precision.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>rsqrtf</samp>’</dt>
|
||
|
|
<dd><p>Enable the single-precision reciprocal square root approximation instructions.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt>‘<samp>rsqrtd</samp>’</dt>
|
||
|
|
<dd><p>Enable the double-precision reciprocal square root approximation instructions.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>So, for example, <samp>-mrecip=all,!rsqrtd</samp> enables
|
||
|
|
all of the reciprocal estimate instructions, except for the
|
||
|
|
<code>FRSQRTE</code>, <code>XSRSQRTEDP</code>, and <code>XVRSQRTEDP</code> instructions
|
||
|
|
which handle the double-precision reciprocal square root calculations.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mrecip-precision</code></dt>
|
||
|
|
<dt><code>-mno-recip-precision</code></dt>
|
||
|
|
<dd><a name="index-mrecip_002dprecision"></a>
|
||
|
|
<p>Assume (do not assume) that the reciprocal estimate instructions
|
||
|
|
provide higher-precision estimates than is mandated by the PowerPC
|
||
|
|
ABI. Selecting <samp>-mcpu=power6</samp>, <samp>-mcpu=power7</samp> or
|
||
|
|
<samp>-mcpu=power8</samp> automatically selects <samp>-mrecip-precision</samp>.
|
||
|
|
The double-precision square root estimate instructions are not generated by
|
||
|
|
default on low-precision machines, since they do not provide an
|
||
|
|
estimate that converges after three steps.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mpointers-to-nested-functions</code></dt>
|
||
|
|
<dt><code>-mno-pointers-to-nested-functions</code></dt>
|
||
|
|
<dd><a name="index-mpointers_002dto_002dnested_002dfunctions"></a>
|
||
|
|
<p>Generate (do not generate) code to load up the static chain register
|
||
|
|
(<code>r11</code>) when calling through a pointer on AIX and 64-bit Linux
|
||
|
|
systems where a function pointer points to a 3-word descriptor giving
|
||
|
|
the function address, TOC value to be loaded in register <code>r2</code>, and
|
||
|
|
static chain value to be loaded in register <code>r11</code>. The
|
||
|
|
<samp>-mpointers-to-nested-functions</samp> is on by default. You cannot
|
||
|
|
call through pointers to nested functions or pointers
|
||
|
|
to functions compiled in other languages that use the static chain if
|
||
|
|
you use <samp>-mno-pointers-to-nested-functions</samp>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-msave-toc-indirect</code></dt>
|
||
|
|
<dt><code>-mno-save-toc-indirect</code></dt>
|
||
|
|
<dd><a name="index-msave_002dtoc_002dindirect"></a>
|
||
|
|
<p>Generate (do not generate) code to save the TOC value in the reserved
|
||
|
|
stack location in the function prologue if the function calls through
|
||
|
|
a pointer on AIX and 64-bit Linux systems. If the TOC value is not
|
||
|
|
saved in the prologue, it is saved just before the call through the
|
||
|
|
pointer. The <samp>-mno-save-toc-indirect</samp> option is the default.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mcompat-align-parm</code></dt>
|
||
|
|
<dt><code>-mno-compat-align-parm</code></dt>
|
||
|
|
<dd><a name="index-mcompat_002dalign_002dparm"></a>
|
||
|
|
<p>Generate (do not generate) code to pass structure parameters with a
|
||
|
|
maximum alignment of 64 bits, for compatibility with older versions
|
||
|
|
of GCC.
|
||
|
|
</p>
|
||
|
|
<p>Older versions of GCC (prior to 4.9.0) incorrectly did not align a
|
||
|
|
structure parameter on a 128-bit boundary when that structure contained
|
||
|
|
a member requiring 128-bit alignment. This is corrected in more
|
||
|
|
recent versions of GCC. This option may be used to generate code
|
||
|
|
that is compatible with functions compiled with older versions of
|
||
|
|
GCC.
|
||
|
|
</p>
|
||
|
|
<p>The <samp>-mno-compat-align-parm</samp> option is the default.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><code>-mstack-protector-guard=<var>guard</var></code></dt>
|
||
|
|
<dt><code>-mstack-protector-guard-reg=<var>reg</var></code></dt>
|
||
|
|
<dt><code>-mstack-protector-guard-offset=<var>offset</var></code></dt>
|
||
|
|
<dt><code>-mstack-protector-guard-symbol=<var>symbol</var></code></dt>
|
||
|
|
<dd><a name="index-mstack_002dprotector_002dguard"></a>
|
||
|
|
<a name="index-mstack_002dprotector_002dguard_002dreg"></a>
|
||
|
|
<a name="index-mstack_002dprotector_002dguard_002doffset"></a>
|
||
|
|
<a name="index-mstack_002dprotector_002dguard_002dsymbol"></a>
|
||
|
|
<p>Generate stack protection code using canary at <var>guard</var>. Supported
|
||
|
|
locations are ‘<samp>global</samp>’ for global canary or ‘<samp>tls</samp>’ for per-thread
|
||
|
|
canary in the TLS block (the default with GNU libc version 2.4 or later).
|
||
|
|
</p>
|
||
|
|
<p>With the latter choice the options
|
||
|
|
<samp>-mstack-protector-guard-reg=<var>reg</var></samp> and
|
||
|
|
<samp>-mstack-protector-guard-offset=<var>offset</var></samp> furthermore specify
|
||
|
|
which register to use as base register for reading the canary, and from what
|
||
|
|
offset from that base register. The default for those is as specified in the
|
||
|
|
relevant ABI. <samp>-mstack-protector-guard-symbol=<var>symbol</var></samp> overrides
|
||
|
|
the offset with a symbol reference to a canary in the TLS block.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="RISC_002dV-Options.html#RISC_002dV-Options" accesskey="n" rel="next">RISC-V Options</a>, Previous: <a href="PowerPC-Options.html#PowerPC-Options" accesskey="p" rel="prev">PowerPC Options</a>, Up: <a href="Submodel-Options.html#Submodel-Options" accesskey="u" rel="up">Submodel Options</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>
|