| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <!-- Copyright (C) 1988-2015 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being "Funding Free Software", the Front-Cover |
| Texts being (a) (see below), and with the Back-Cover Texts being (b) |
| (see below). A copy of the license is included in the section entitled |
| "GNU Free Documentation License". |
| |
| (a) The FSF's Front-Cover Text is: |
| |
| A GNU Manual |
| |
| (b) The FSF's Back-Cover Text is: |
| |
| You have freedom to copy and modify this GNU Manual, like GNU |
| software. Copies published by the Free Software Foundation raise |
| funds for GNU development. --> |
| <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> |
| <head> |
| <title>Using the GNU Compiler Collection (GCC): Adapteva Epiphany Options</title> |
| |
| <meta name="description" content="Using the GNU Compiler Collection (GCC): Adapteva Epiphany Options"> |
| <meta name="keywords" content="Using the GNU Compiler Collection (GCC): Adapteva Epiphany Options"> |
| <meta name="resource-type" content="document"> |
| <meta name="distribution" content="global"> |
| <meta name="Generator" content="makeinfo"> |
| <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> |
| <link href="index.html#Top" rel="start" title="Top"> |
| <link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> |
| <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> |
| <link href="Submodel-Options.html#Submodel-Options" rel="up" title="Submodel Options"> |
| <link href="ARC-Options.html#ARC-Options" rel="next" title="ARC Options"> |
| <link href="AArch64-Options.html#AArch64-Options" rel="prev" title="AArch64 Options"> |
| <style type="text/css"> |
| <!-- |
| a.summary-letter {text-decoration: none} |
| blockquote.smallquotation {font-size: smaller} |
| div.display {margin-left: 3.2em} |
| div.example {margin-left: 3.2em} |
| div.indentedblock {margin-left: 3.2em} |
| div.lisp {margin-left: 3.2em} |
| div.smalldisplay {margin-left: 3.2em} |
| div.smallexample {margin-left: 3.2em} |
| div.smallindentedblock {margin-left: 3.2em; font-size: smaller} |
| div.smalllisp {margin-left: 3.2em} |
| kbd {font-style:oblique} |
| pre.display {font-family: inherit} |
| pre.format {font-family: inherit} |
| pre.menu-comment {font-family: serif} |
| pre.menu-preformatted {font-family: serif} |
| pre.smalldisplay {font-family: inherit; font-size: smaller} |
| pre.smallexample {font-size: smaller} |
| pre.smallformat {font-family: inherit; font-size: smaller} |
| pre.smalllisp {font-size: smaller} |
| span.nocodebreak {white-space:nowrap} |
| span.nolinebreak {white-space:nowrap} |
| span.roman {font-family:serif; font-weight:normal} |
| span.sansserif {font-family:sans-serif; font-weight:normal} |
| ul.no-bullet {list-style: none} |
| --> |
| </style> |
| |
| |
| </head> |
| |
| <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> |
| <a name="Adapteva-Epiphany-Options"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="ARC-Options.html#ARC-Options" accesskey="n" rel="next">ARC Options</a>, Previous: <a href="AArch64-Options.html#AArch64-Options" accesskey="p" rel="prev">AArch64 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> |
| <hr> |
| <a name="Adapteva-Epiphany-Options-1"></a> |
| <h4 class="subsection">3.17.2 Adapteva Epiphany Options</h4> |
| |
| <p>These ‘<samp>-m</samp>’ options are defined for Adapteva Epiphany: |
| </p> |
| <dl compact="compact"> |
| <dt><code>-mhalf-reg-file</code></dt> |
| <dd><a name="index-mhalf_002dreg_002dfile"></a> |
| <p>Don’t allocate any register in the range <code>r32</code>…<code>r63</code>. |
| That allows code to run on hardware variants that lack these registers. |
| </p> |
| </dd> |
| <dt><code>-mprefer-short-insn-regs</code></dt> |
| <dd><a name="index-mprefer_002dshort_002dinsn_002dregs"></a> |
| <p>Preferrentially allocate registers that allow short instruction generation. |
| This can result in increased instruction count, so this may either reduce or |
| increase overall code size. |
| </p> |
| </dd> |
| <dt><code>-mbranch-cost=<var>num</var></code></dt> |
| <dd><a name="index-mbranch_002dcost"></a> |
| <p>Set the cost of branches to roughly <var>num</var> “simple” instructions. |
| This cost is only a heuristic and is not guaranteed to produce |
| consistent results across releases. |
| </p> |
| </dd> |
| <dt><code>-mcmove</code></dt> |
| <dd><a name="index-mcmove"></a> |
| <p>Enable the generation of conditional moves. |
| </p> |
| </dd> |
| <dt><code>-mnops=<var>num</var></code></dt> |
| <dd><a name="index-mnops"></a> |
| <p>Emit <var>num</var> NOPs before every other generated instruction. |
| </p> |
| </dd> |
| <dt><code>-mno-soft-cmpsf</code></dt> |
| <dd><a name="index-mno_002dsoft_002dcmpsf"></a> |
| <p>For single-precision floating-point comparisons, emit an <code>fsub</code> instruction |
| and test the flags. This is faster than a software comparison, but can |
| get incorrect results in the presence of NaNs, or when two different small |
| numbers are compared such that their difference is calculated as zero. |
| The default is <samp>-msoft-cmpsf</samp>, which uses slower, but IEEE-compliant, |
| software comparisons. |
| </p> |
| </dd> |
| <dt><code>-mstack-offset=<var>num</var></code></dt> |
| <dd><a name="index-mstack_002doffset"></a> |
| <p>Set the offset between the top of the stack and the stack pointer. |
| E.g., a value of 8 means that the eight bytes in the range <code>sp+0…sp+7</code> |
| can be used by leaf functions without stack allocation. |
| Values other than ‘<samp>8</samp>’ or ‘<samp>16</samp>’ are untested and unlikely to work. |
| Note also that this option changes the ABI; compiling a program with a |
| different stack offset than the libraries have been compiled with |
| generally does not work. |
| This option can be useful if you want to evaluate if a different stack |
| offset would give you better code, but to actually use a different stack |
| offset to build working programs, it is recommended to configure the |
| toolchain with the appropriate <samp>--with-stack-offset=<var>num</var></samp> option. |
| </p> |
| </dd> |
| <dt><code>-mno-round-nearest</code></dt> |
| <dd><a name="index-mno_002dround_002dnearest"></a> |
| <p>Make the scheduler assume that the rounding mode has been set to |
| truncating. The default is <samp>-mround-nearest</samp>. |
| </p> |
| </dd> |
| <dt><code>-mlong-calls</code></dt> |
| <dd><a name="index-mlong_002dcalls"></a> |
| <p>If not otherwise specified by an attribute, assume all calls might be beyond |
| the offset range of the <code>b</code> / <code>bl</code> instructions, and therefore load the |
| function address into a register before performing a (otherwise direct) call. |
| This is the default. |
| </p> |
| </dd> |
| <dt><code>-mshort-calls</code></dt> |
| <dd><a name="index-short_002dcalls"></a> |
| <p>If not otherwise specified by an attribute, assume all direct calls are |
| in the range of the <code>b</code> / <code>bl</code> instructions, so use these instructions |
| for direct calls. The default is <samp>-mlong-calls</samp>. |
| </p> |
| </dd> |
| <dt><code>-msmall16</code></dt> |
| <dd><a name="index-msmall16"></a> |
| <p>Assume addresses can be loaded as 16-bit unsigned values. This does not |
| apply to function addresses for which <samp>-mlong-calls</samp> semantics |
| are in effect. |
| </p> |
| </dd> |
| <dt><code>-mfp-mode=<var>mode</var></code></dt> |
| <dd><a name="index-mfp_002dmode"></a> |
| <p>Set the prevailing mode of the floating-point unit. |
| This determines the floating-point mode that is provided and expected |
| at function call and return time. Making this mode match the mode you |
| predominantly need at function start can make your programs smaller and |
| faster by avoiding unnecessary mode switches. |
| </p> |
| <p><var>mode</var> can be set to one the following values: |
| </p> |
| <dl compact="compact"> |
| <dt>‘<samp>caller</samp>’</dt> |
| <dd><p>Any mode at function entry is valid, and retained or restored when |
| the function returns, and when it calls other functions. |
| This mode is useful for compiling libraries or other compilation units |
| you might want to incorporate into different programs with different |
| prevailing FPU modes, and the convenience of being able to use a single |
| object file outweighs the size and speed overhead for any extra |
| mode switching that might be needed, compared with what would be needed |
| with a more specific choice of prevailing FPU mode. |
| </p> |
| </dd> |
| <dt>‘<samp>truncate</samp>’</dt> |
| <dd><p>This is the mode used for floating-point calculations with |
| truncating (i.e. round towards zero) rounding mode. That includes |
| conversion from floating point to integer. |
| </p> |
| </dd> |
| <dt>‘<samp>round-nearest</samp>’</dt> |
| <dd><p>This is the mode used for floating-point calculations with |
| round-to-nearest-or-even rounding mode. |
| </p> |
| </dd> |
| <dt>‘<samp>int</samp>’</dt> |
| <dd><p>This is the mode used to perform integer calculations in the FPU, e.g. |
| integer multiply, or integer multiply-and-accumulate. |
| </p></dd> |
| </dl> |
| |
| <p>The default is <samp>-mfp-mode=caller</samp> |
| </p> |
| </dd> |
| <dt><code>-mnosplit-lohi</code></dt> |
| <dt><code>-mno-postinc</code></dt> |
| <dt><code>-mno-postmodify</code></dt> |
| <dd><a name="index-mnosplit_002dlohi"></a> |
| <a name="index-mno_002dpostinc"></a> |
| <a name="index-mno_002dpostmodify"></a> |
| <p>Code generation tweaks that disable, respectively, splitting of 32-bit |
| loads, generation of post-increment addresses, and generation of |
| post-modify addresses. The defaults are <samp>msplit-lohi</samp>, |
| <samp>-mpost-inc</samp>, and <samp>-mpost-modify</samp>. |
| </p> |
| </dd> |
| <dt><code>-mnovect-double</code></dt> |
| <dd><a name="index-mno_002dvect_002ddouble"></a> |
| <p>Change the preferred SIMD mode to SImode. The default is |
| <samp>-mvect-double</samp>, which uses DImode as preferred SIMD mode. |
| </p> |
| </dd> |
| <dt><code>-max-vect-align=<var>num</var></code></dt> |
| <dd><a name="index-max_002dvect_002dalign"></a> |
| <p>The maximum alignment for SIMD vector mode types. |
| <var>num</var> may be 4 or 8. The default is 8. |
| Note that this is an ABI change, even though many library function |
| interfaces are unaffected if they don’t use SIMD vector modes |
| in places that affect size and/or alignment of relevant types. |
| </p> |
| </dd> |
| <dt><code>-msplit-vecmove-early</code></dt> |
| <dd><a name="index-msplit_002dvecmove_002dearly"></a> |
| <p>Split vector moves into single word moves before reload. In theory this |
| can give better register allocation, but so far the reverse seems to be |
| generally the case. |
| </p> |
| </dd> |
| <dt><code>-m1reg-<var>reg</var></code></dt> |
| <dd><a name="index-m1reg_002d"></a> |
| <p>Specify a register to hold the constant -1, which makes loading small negative |
| constants and certain bitmasks faster. |
| Allowable values for <var>reg</var> are ‘<samp>r43</samp>’ and ‘<samp>r63</samp>’, |
| which specify use of that register as a fixed register, |
| and ‘<samp>none</samp>’, which means that no register is used for this |
| purpose. The default is <samp>-m1reg-none</samp>. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="ARC-Options.html#ARC-Options" accesskey="n" rel="next">ARC Options</a>, Previous: <a href="AArch64-Options.html#AArch64-Options" accesskey="p" rel="prev">AArch64 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> |
