You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
93 lines
5.2 KiB
HTML
93 lines
5.2 KiB
HTML
4 years ago
|
<html lang="en">
|
||
|
|
<head>
|
||
|
|
<title>H8/300 - Untitled</title>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html">
|
||
|
|
<meta name="description" content="Untitled">
|
||
|
|
<meta name="generator" content="makeinfo 4.13">
|
||
|
|
<link title="Top" rel="start" href="index.html#Top">
|
||
|
|
<link rel="up" href="Machine-Dependent.html#Machine-Dependent" title="Machine Dependent">
|
||
|
|
<link rel="next" href="i960.html#i960" title="i960">
|
||
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
||
|
|
<!--
|
||
|
|
This file documents the GNU linker LD
|
||
|
|
(GNU Binutils)
|
||
|
|
version 2.26.
|
||
|
|
|
||
|
|
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''.-->
|
||
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
||
|
|
<style type="text/css"><!--
|
||
|
|
pre.display { font-family:inherit }
|
||
|
|
pre.format { font-family:inherit }
|
||
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
||
|
|
pre.smallexample { font-size:smaller }
|
||
|
|
pre.smalllisp { font-size:smaller }
|
||
|
|
span.sc { font-variant:small-caps }
|
||
|
|
span.roman { font-family:serif; font-weight:normal; }
|
||
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
||
|
|
--></style>
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
<div class="node">
|
||
|
|
<a name="H8%2f300"></a>
|
||
|
|
<a name="H8_002f300"></a>
|
||
|
|
<p>
|
||
|
|
Next: <a rel="next" accesskey="n" href="i960.html#i960">i960</a>,
|
||
|
|
Up: <a rel="up" accesskey="u" href="Machine-Dependent.html#Machine-Dependent">Machine Dependent</a>
|
||
|
|
<hr>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
<h3 class="section">4.1 <samp><span class="command">ld</span></samp> and the H8/300</h3>
|
||
|
|
|
||
|
|
<p><a name="index-H8_002f300-support-594"></a>For the H8/300, <samp><span class="command">ld</span></samp> can perform these global optimizations when
|
||
|
|
you specify the ‘<samp><span class="samp">--relax</span></samp>’ command-line option.
|
||
|
|
|
||
|
|
|
||
|
|
<a name="index-relaxing-on-H8_002f300-595"></a>
|
||
|
|
<dl><dt><em>relaxing address modes</em><dd><samp><span class="command">ld</span></samp> 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_002f300-596"></a><br><dt><em>synthesizing instructions</em><dd><!-- FIXME: specifically mov.b, or any mov instructions really? -> mov.b only, at least on H8, H8H, H8S -->
|
||
|
|
<samp><span class="command">ld</span></samp> 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><span class="samp">mov.b </span><code>@</code><var>aa</var><span class="samp">:16</span></samp>’ into
|
||
|
|
‘<samp><span class="samp">mov.b </span><code>@</code><var>aa</var><span class="samp">:8</span></samp>’ whenever the address <var>aa</var> is in the
|
||
|
|
top page of memory).
|
||
|
|
|
||
|
|
<p><samp><span class="command">ld</span></samp> 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><span class="samp">mov.b
|
||
|
|
</span><code>@</code><var>d</var><span class="samp">:32,ERx</span></samp>’ into ‘<samp><span class="samp">mov.b </span><code>@</code><var>d</var><span class="samp">:16,ERx</span></samp>’
|
||
|
|
whenever the displacement <var>d</var> is in the 16 bit signed integer
|
||
|
|
range. Only implemented in ELF-format ld).
|
||
|
|
|
||
|
|
<br><dt><em>bit manipulation instructions</em><dd><samp><span class="command">ld</span></samp> 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><span class="samp">bset #xx:3,</span><code>@</code><var>aa</var><span class="samp">:32</span></samp>’ into
|
||
|
|
‘<samp><span class="samp">bset #xx:3,</span><code>@</code><var>aa</var><span class="samp">:8</span></samp>’ whenever the address <var>aa</var> is in
|
||
|
|
the top page of memory).
|
||
|
|
|
||
|
|
<br><dt><em>system control instructions</em><dd><samp><span class="command">ld</span></samp> 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><span class="samp">ldc.w </span><code>@</code><var>aa</var><span class="samp">:32,ccr</span></samp>’ into
|
||
|
|
‘<samp><span class="samp">ldc.w </span><code>@</code><var>aa</var><span class="samp">:16,ccr</span></samp>’ whenever the address <var>aa</var> is in
|
||
|
|
the top page of memory).
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
</body></html>
|
||
|
|
|