Mercurial > hg > index.cgi
view docs/manual/x218.html @ 416:b4d0eafc5bfe
Fix code generation error in gcc6809
It turned out that under some circumstances, the gcc optimizer would select
an instruction sequence that had the sense of a branch inverted. It seems
this was due to a particular instruction pattern included in the machine
description not being quite right with respect to how the condition codes
were tracked. Removing that instruction pattern seems to fix things
(subtraction with the arguments reversed). gcc seems to be smart enough to
figure out how to reorganize code to work without this reversed sense
subtraction and then do the right thing.
author | William Astle <lost@l-w.ca> |
---|---|
date | Thu, 24 Mar 2016 20:07:20 -0600 |
parents | fc166b3bbae3 |
children |
line wrap: on
line source
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Dialects</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="LW Tool Chain" HREF="index.html"><LINK REL="UP" TITLE="LWASM" HREF="c62.html"><LINK REL="PREVIOUS" TITLE="LWASM" HREF="c62.html"><LINK REL="NEXT" TITLE="Source Format" HREF="x227.html"></HEAD ><BODY CLASS="SECTION" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >LW Tool Chain</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="c62.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 3. LWASM</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x227.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECTION" ><H1 CLASS="SECTION" ><A NAME="AEN218" >3.2. Dialects</A ></H1 ><P > LWASM supports all documented MC6809 instructions as defined by Motorola. By default, this does not include any MC6800 compatibility instructions. As of LWASM 4.11, those compatibility instructions can be enabled using the <CODE CLASS="PARAMETER" >--6800compat</CODE > option or the <CODE CLASS="PARAMETER" >6800compat</CODE > pragma. It also supports all known HD6309 instructions. While there is general agreement on the pneumonics for most of the 6309 instructions, there is some variance with the block transfer instructions. TFM for all four variations seems to have gained the most traction and, thus, this is the form that is recommended for LWASM. However, it also supports COPY, COPY-, IMP, EXP, TFRP, TFRM, TFRS, and TFRR. It further adds COPY+ as a synomym for COPY, IMPLODE for IMP, and EXPAND for EXP. </P ><P >By default, LWASM accepts 6309 instructions. However, using the <CODE CLASS="PARAMETER" >--6809</CODE > parameter, you can cause it to throw errors on 6309 instructions instead.</P ><P >The standard addressing mode specifiers are supported. These are the hash sign ("#") for immediate mode, the less than sign ("<") for forced eight bit modes, and the greater than sign (">") for forced sixteen bit modes.</P ><P >Additionally, LWASM supports using the asterisk ("*") to indicate base page addressing. This should not be used in hand-written source code, however, because it is non-standard and may or may not be present in future versions of LWASM.</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="c62.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="x227.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >LWASM</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="c62.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Source Format</TD ></TR ></TABLE ></DIV ></BODY ></HTML >