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Correct bug in the object file output code leading to stack corruption
It turns out leaving a pointer to a stack allocated temporary in a
persistent data structure is not conducive to correct program operation.
Undo the export check setup in the object file output sequence so a
pointer to stack allocated memory is not left hanging when the function
returns. This seems to correct at least one mysterious crash bug, and
possibly others.
Thanks to Boisy Pitre for reporting the crash bug that led to this
discovery, as well as a previous crash bug that likely has the same
root cause.
Additional thanks to Ciaran Anscomb whose debugger wielding wizardry
revealed the exact location of this particular bit of unbrilliance.
author | William Astle <lost@l-w.ca> |
---|---|
date | Sat, 03 Aug 2024 14:30:06 -0600 |
parents | 52af0aa54fe5 |
children |
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Symbols</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="Source Format" HREF="x238.html"><LINK REL="NEXT" TITLE="Numbers and Expressions" HREF="x253.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="x238.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="x253.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECTION" ><H1 CLASS="SECTION" ><A NAME="AEN248" >3.4. Symbols</A ></H1 ><P >Symbols have no length restriction. They may contain letters, numbers, dots, dollar signs, and underscores. They must start with a letter, dot, or underscore.</P ><P >LWASM also supports the concept of a local symbol. A local symbol is one which contains either a "?" or a "@", which can appear anywhere in the symbol. The scope of a local symbol is determined by a number of factors. First, each included file gets its own local symbol scope. A blank line will also be considered a local scope barrier. Macros each have their own local symbol scope as well (which has a side effect that you cannot use a local symbol as an argument to a macro). There are other factors as well. In general, a local symbol is restricted to the block of code it is defined within.</P ><P >By default, unless assembling to the os9 target, a "$" in the symbol will also make it local. This can be controlled by the "dollarlocal" and "nodollarlocal" pragmas. In the absence of a pragma to the contrary, for the os9 target, a "$" in the symbol will not make it considered local while for all other targets it will.</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="x238.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="x253.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Source Format</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="c62.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Numbers and Expressions</TD ></TR ></TABLE ></DIV ></BODY ></HTML >