| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <!-- This file documents the GNU linker LD |
| (Linaro GDB 2015.08) |
| version 2.25.51. |
| |
| Copyright (C) 1991-2015 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 no Invariant Sections, with no Front-Cover Texts, and with no |
| Back-Cover Texts. A copy of the license is included in the |
| section entitled "GNU Free Documentation License". --> |
| <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> |
| <head> |
| <title>LD: H8/300</title> |
| |
| <meta name="description" content="LD: H8/300"> |
| <meta name="keywords" content="LD: H8/300"> |
| <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="LD-Index.html#LD-Index" rel="index" title="LD Index"> |
| <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> |
| <link href="Machine-Dependent.html#Machine-Dependent" rel="up" title="Machine Dependent"> |
| <link href="i960.html#i960" rel="next" title="i960"> |
| <link href="Machine-Dependent.html#Machine-Dependent" rel="prev" title="Machine Dependent"> |
| <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="H8_002f300"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="i960.html#i960" accesskey="n" rel="next">i960</a>, Up: <a href="Machine-Dependent.html#Machine-Dependent" accesskey="u" rel="up">Machine Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <hr> |
| <a name="ld-and-the-H8_002f300"></a> |
| <h3 class="section">4.1 <code>ld</code> and the H8/300</h3> |
| |
| <a name="index-H8_002f300-support"></a> |
| <p>For the H8/300, <code>ld</code> can perform these global optimizations when |
| you specify the ‘<samp>--relax</samp>’ command-line option. |
| </p> |
| <dl compact="compact"> |
| <dd><a name="index-relaxing-on-H8_002f300"></a> |
| </dd> |
| <dt><em>relaxing address modes</em></dt> |
| <dd><p><code>ld</code> finds all <code>jsr</code> and <code>jmp</code> instructions whose |
| targets are within eight bits, and turns them into eight-bit |
| program-counter relative <code>bsr</code> and <code>bra</code> instructions, |
| respectively. |
| </p> |
| <a name="index-synthesizing-on-H8_002f300"></a> |
| </dd> |
| <dt><em>synthesizing instructions</em></dt> |
| <dd><p><code>ld</code> finds all <code>mov.b</code> instructions which use the |
| sixteen-bit absolute address form, but refer to the top |
| page of memory, and changes them to use the eight-bit address form. |
| (That is: the linker turns ‘<samp>mov.b <code>@</code><var>aa</var>:16</samp>’ into |
| ‘<samp>mov.b <code>@</code><var>aa</var>:8</samp>’ whenever the address <var>aa</var> is in the |
| top page of memory). |
| </p> |
| <p><code>ld</code> finds all <code>mov</code> instructions which use the register |
| indirect with 32-bit displacement addressing mode, but use a small |
| displacement inside 16-bit displacement range, and changes them to use |
| the 16-bit displacement form. (That is: the linker turns ‘<samp>mov.b |
| <code>@</code><var>d</var>:32,ERx</samp>’ into ‘<samp>mov.b <code>@</code><var>d</var>:16,ERx</samp>’ |
| whenever the displacement <var>d</var> is in the 16 bit signed integer |
| range. Only implemented in ELF-format ld). |
| </p> |
| </dd> |
| <dt><em>bit manipulation instructions</em></dt> |
| <dd><p><code>ld</code> finds all bit manipulation instructions like <code>band, bclr, |
| biand, bild, bior, bist, bixor, bld, bnot, bor, bset, bst, btst, bxor</code> |
| which use 32 bit and 16 bit absolute address form, but refer to the top |
| page of memory, and changes them to use the 8 bit address form. |
| (That is: the linker turns ‘<samp>bset #xx:3,<code>@</code><var>aa</var>:32</samp>’ into |
| ‘<samp>bset #xx:3,<code>@</code><var>aa</var>:8</samp>’ whenever the address <var>aa</var> is in |
| the top page of memory). |
| </p> |
| </dd> |
| <dt><em>system control instructions</em></dt> |
| <dd><p><code>ld</code> finds all <code>ldc.w, stc.w</code> instructions which use the |
| 32 bit absolute address form, but refer to the top page of memory, and |
| changes them to use 16 bit address form. |
| (That is: the linker turns ‘<samp>ldc.w <code>@</code><var>aa</var>:32,ccr</samp>’ into |
| ‘<samp>ldc.w <code>@</code><var>aa</var>:16,ccr</samp>’ whenever the address <var>aa</var> is in |
| the top page of memory). |
| </p></dd> |
| </dl> |
| |
| |
| |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="i960.html#i960" accesskey="n" rel="next">i960</a>, Up: <a href="Machine-Dependent.html#Machine-Dependent" accesskey="u" rel="up">Machine Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p> |
| </div> |
| |
| |
| |
| </body> |
| </html> |
