Files
ioccc/1986/marshall/compilers.html
T
Landon Curt Noll 11dfe51c6c move IOCCC Quick Start Guide
Created `quick-start.md` to hold the FAQ 0.0 content.

Used `sgit(1)` to change:

* faq.html#enter ==> quick-start.html#enter
* faq.html#enter_questions ==> quick-start.html#enter_questions
* faq.html#step_0 ==> quick-start.html#step_0
* faq.html#step_1 ==> quick-start.html#step_1
* faq.html#step_2 ==> quick-start.html#step_2
* faq.html#register ==> quick-start.html#register
* faq.html#step_3 ==> quick-start.html#step_3
* faq.html#step_4 ==> quick-start.html#step_4
* faq.html#step_5 ==> quick-start.html#step_5
* faq.html#step_6 ==> quick-start.html#step_6
* faq.html#step_7 ==> quick-start.html#step_7
* faq.html#step_submit ==> quick-start.html#step_submit

Via:

```sh
sgit -e 's/faq\.html#enter/quick-start.html#enter/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#enter_questions/quick-start.html#enter_questions/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_0/quick-start.html#step_0/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_1/quick-start.html#step_1/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_2/quick-start.html#step_2/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#register/quick-start.html#register/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_3/quick-start.html#step_3/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_4/quick-start.html#step_4/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_5/quick-start.html#step_5/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_6/quick-start.html#step_6/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_7/quick-start.html#step_7/g' '*.md' '*.hdr' 'inc/*.html'
sgit -e 's/faq\.html#step_submit/quick-start.html#step_submit/g' '*.md' '*.hdr' 'inc/*.html'
```

The former FAQ 0.0 section in `faq.html` now just refers to `quick-start.html`.

Modified menu and non-JS menu so that "Enter the IOCCC" refers to `quick-start.html`.

Changed `bin/gen-top-html.sh` VERSION from "1.4.10 2024-11-23"
to "1.4.11 2025-01-09".

Performed `make www` on macOS to complete the above.
2025-01-09 23:11:43 -08:00

584 lines
21 KiB
HTML
Raw Blame History

This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<!-- START: two lines up starts content from: inc/top.default.html -->
<!-- END: this line ends content from: inc/top.default.html -->
<!-- START: this line starts content from: inc/head.default.html -->
<head>
<link rel="stylesheet" href="../../ioccc.css">
<link href="https://fonts.googleapis.com/css2?family=Outfit:wght@100..900&display=swap" rel="stylesheet">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>The International Obfuscated C Code Contest</title>
<link rel="icon" type="image/x-icon" href="../../favicon.ico">
<meta name="description" content="compilers.md for 1986/marshall">
<meta name="keywords" content="IOCCC, 1986/marshall, compilers.md">
</head>
<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
<!-- !!! DO NOT MODIFY THIS FILE - This file is generated by a tool !!! -->
<!-- !!! DO NOT MODIFY THIS FILE - This file is generated by a tool !!! -->
<!-- !!! DO NOT MODIFY THIS FILE - This file is generated by a tool !!! -->
<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
<!-- END: this line ends content from: inc/head.default.html -->
<!-- -->
<!-- This web page was formed via the tool: bin/gen-other-html.sh -->
<!-- The content of main section of this web page came from: 1986/marshall/compilers.md -->
<!-- -->
<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
<!-- !!! Do not modify this web page, instead modify the file: 1986/marshall/compilers.md !!! -->
<!-- !!! Do not modify this web page, instead modify the file: 1986/marshall/compilers.md !!! -->
<!-- !!! Do not modify this web page, instead modify the file: 1986/marshall/compilers.md !!! -->
<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
<!-- Markdown content was converted into HTML via the tool: bin/md2html.sh -->
<!-- START: this line starts content from: inc/body.default.html -->
<body>
<!-- END: this line ends content from: inc/body.default.html -->
<!-- START: this line starts content from: inc/topbar.default.html -->
<div class="theader">
<nav class="topbar">
<div class="container">
<div class="logo">
<a href="../../index.html" class="logo-link">
IOCCC
</a>
</div>
<div class="topbar-items">
<div class="item">
<span class="item-header">
Entries
</span>
<div class="sub-item">
<div class="outfit-font">
<a href="../../years.html" class="sub-item-link">
Winning entries
</a>
</div>
<div class="outfit-font">
<a href="../../authors.html" class="sub-item-link">
Winning authors
</a>
</div>
<div class="outfit-font">
<a href="../../location.html" class="sub-item-link">
Location of authors
</a>
</div>
<div class="outfit-font">
<a href="../../bugs.html" class="sub-item-link">
Bugs and (mis)features
</a>
</div>
<div class="outfit-font">
<a href="../../faq.html#fix_an_entry" class="sub-item-link">
Fixing entries
</a>
</div>
<div class="outfit-font">
<a href="../../faq.html#fix_author" class="sub-item-link">
Updating author info
</a>
</div>
</div>
</div>
<div class="item">
<span class="item-header">
Status
</span>
<div class="sub-item">
<div class="outfit-font">
<a href="../../news.html" class="sub-item-link">
News
</a>
</div>
<div class="outfit-font">
<a href="../../status.html" class="sub-item-link">
Contest status
</a>
</div>
<div class="outfit-font">
<a href="../../next/index.html" class="sub-item-link">
Rules and guidelines
</a>
</div>
<div class="outfit-font">
<a href="../../markdown.html" class="sub-item-link">
Markdown guidelines
</a>
</div>
<div class="outfit-font">
<a href="../../SECURITY.html" class="sub-item-link">
Security policy
</a>
</div>
</div>
</div>
<div class="item">
<span class="item-header">
FAQ
</span>
<div class="sub-item">
<div class="outfit-font">
<a href="../../faq.html" class="sub-item-link">
Frequently Asked Questions
</a>
</div>
<div class="outfit-font">
<a href="../../quick-start.html#enter" class="sub-item-link">
Enter the IOCCC
</a>
</div>
<div class="outfit-font">
<a href="../../faq.html#compiling" class="sub-item-link">
Compiling entries
</a>
</div>
<div class="outfit-font">
<a href="../../faq.html#running_entries" class="sub-item-link">
Running entries
</a>
</div>
<div class="outfit-font">
<a href="../../faq.html#help" class="sub-item-link">
How to help
</a>
</div>
</div>
</div>
<div class="item">
<span class="item-header">
About
</span>
<div class="sub-item">
<div class="outfit-font">
<a href="../../index.html" class="sub-item-link">
Home page
</a>
</div>
<div class="outfit-font">
<a href="../../about.html" class="sub-item-link">
About the IOCCC
</a>
</div>
<div class="outfit-font">
<a href="../../judges.html" class="sub-item-link">
The Judges
</a>
</div>
<div class="outfit-font">
<a href="../../thanks-for-help.html" class="sub-item-link">
Thanks for the help
</a>
</div>
<div class="outfit-font">
<a href="../../contact.html" class="sub-item-link">
Contact us
</a>
</div>
</div>
</div>
</div>
</div>
</nav>
<div class="header-mobile-menu">
<noscript>
<a href="../../nojs-menu.html" class="topbar-js-label">
Please Enable JavaScript
</a>
</noscript>
<button id="header-open-menu-button" class="topbar-mobile-menu">
<img
src="../../png/hamburger-icon-open.png"
alt="hamburger style menu icon - open state"
width=48
height=48>
</button>
<button id="header-close-menu-button" class="hide-content">
<img
src="../../png/hamburger-icon-closed.png"
alt="hamburger style menu icon - closed state"
width=48
height=48>
</button>
<div id="mobile-menu-panel" class="hide-content">
<div class="mobile-menu-container">
<div class="mobile-menu-wrapper">
<div class="mobile-menu-item">
Entries
</div>
<div class="mobile-submenu-wrapper">
<a class="mobile-submenu-item" href="../../years.html">
Winning entries
</a>
<a class="mobile-submenu-item" href="../../authors.html">
Winning authors
</a>
<a class="mobile-submenu-item" href="../../location.html">
Location of authors
</a>
<a class="mobile-submenu-item" href="../../bugs.html">
Bugs and (mis)features
</a>
<a class="mobile-submenu-item" href="../../faq.html#fix_an_entry">
Fixing entries
</a>
<a class="mobile-submenu-item" href="../../faq.html#fix_author">
Updating author info
</a>
<a class="mobile-submenu-item" href="../../thanks-for-help.html">
Thanks for the help
</a>
</div>
</div>
<div class="mobile-menu-wrapper">
<div class="mobile-menu-item">
Status
</div>
<div class="mobile-submenu-wrapper">
<a class="mobile-submenu-item" href="../../news.html">
News
</a>
<a class="mobile-submenu-item" href="../../status.html">
Contest status
</a>
<a class="mobile-submenu-item" href="../../next/index.html">
Rules and guidelines
</a>
<a class="mobile-submenu-item" href="../../markdown.html">
Markdown guidelines
</a>
<a class="mobile-submenu-item" href="../../SECURITY.html">
Security policy
</a>
</div>
</div>
<div class="mobile-menu-wrapper">
<div class="mobile-menu-item">
FAQ
</div>
<div class="mobile-submenu-wrapper">
<a class="mobile-submenu-item" href="../../faq.html">
Frequently Asked Questions
</a>
<a class="mobile-submenu-item" href="../../quick-start.html#enter">
Enter the IOCCC
</a>
<a class="mobile-submenu-item" href="../../faq.html#compiling">
Compiling entries
</a>
<a class="mobile-submenu-item" href="../../faq.html#running_entries">
Running entries
</a>
<a class="mobile-submenu-item" href="../../faq.html#help">
How to help
</a>
</div>
</div>
<div class="mobile-menu-wrapper">
<div class="mobile-menu-item">
About
</div>
<div class="mobile-submenu-wrapper">
<a class="mobile-submenu-item" href="../../index.html">
Home page
</a>
<a class="mobile-submenu-item" href="../../about.html">
About the IOCCC
</a>
<a class="mobile-submenu-item" href="../../judges.html">
The Judges
</a>
<a class="mobile-submenu-item" href="../../contact.html">
Contact us
</a>
</div>
</div>
</div>
</div>
</div>
</div>
<script>
var headerOpenMenuButton = document.getElementById("header-open-menu-button");
var headerCloseMenuButton = document.getElementById("header-close-menu-button");
var mobileMenuPanel = document.getElementById("mobile-menu-panel");
headerOpenMenuButton.addEventListener("click", () => {
headerOpenMenuButton.classList.remove("topbar-mobile-menu");
headerOpenMenuButton.classList.add("hide-content");
headerCloseMenuButton.classList.remove("hide-content");
headerCloseMenuButton.classList.add("topbar-mobile-menu");
mobileMenuPanel.classList.remove("hide-content");
mobileMenuPanel.classList.add("topbar-mobile-panel");
});
headerCloseMenuButton.addEventListener("click", () => {
headerCloseMenuButton.classList.remove("topbar-mobile-menu");
headerCloseMenuButton.classList.add("hide-content");
mobileMenuPanel.classList.add("hide-content");
mobileMenuPanel.classList.remove("topbar-mobile-panel");
headerOpenMenuButton.classList.add("topbar-mobile-menu");
headerOpenMenuButton.classList.remove("hide-content");
});
</script>
<!-- END: this line ends content from: inc/topbar.default.html -->
<!-- START: this line starts content from: inc/header.default.html -->
<div class="header">
<a href="../../2011/zucker/index.html">
<img src="../../png/ioccc.png"
alt="IOCCC image by Matt Zucker"
width=300
height=110>
</a>
<h1>The International Obfuscated C Code Contest</h1>
<h2>compilers.html for 1986/marshall</h2>
</div>
<!-- END: this line ends content from: inc/header.default.html -->
<!-- START: this line starts content from: inc/navbar.up2index.html -->
<div class="navbar">
<a class="Left" href="index.html">&uarr; jump to 1986/marshall/index.html &uarr;</a>
<a class="Right" href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fwww.ioccc.org%2F1986%2Fmarshall%2Fcompilers.html">&#x2713;</a>
</div>
<!-- END: this line ends content from: inc/navbar.up2index.html -->
<!-- START: this line starts content from: inc/before-content.default.html -->
<div class="content" id="content">
<!-- END: this line ends content from: inc/before-content.default.html -->
<!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
<!-- BEFORE: 1st line of markdown file: 1986/marshall/compilers.md -->
<h1 id="conflicting-compilers-and-optimisers-that-broke-this-entry-in-2023">Conflicting compilers and optimisers that broke this entry in 2023</h1>
<p>As briefly noted in the <a href="index.html">index.html</a> <code>gcc</code> versus <code>clang</code> caused
different problems with this entry, depending on the optimiser being enabled or
disabled, where if the optimiser was enabled it would work with one compiler but
not the other; on the other hand, if you disabled the optimiser the opposite
problem would occur: the working compiler would no longer work and the other one
would! And then there’s the problem of linux versus macOS causing problems.</p>
<p>Using the <a href="https://github.com/ioccc-src/winner/blob/master/1986/marshall/marshall.alt.c">alternate source code</a>
demonstrates the problem so you can see if your compiler has the problem
described below.</p>
<p>In some versions of <code>gcc</code> and <code>clang</code> (this was first discovered in fedora linux 38)
if the optimiser was enabled one compiler would generate code that segfaulted but
the other one did not. However, when disabling the optimiser, the compiler
that had no problem suddenly <em>did</em> and the one that did suddenly <em>did not</em>. But
segfaulting was not by any means the only problem.</p>
<p>Another problem was that depending on the optimiser an infinite loop would be
entered. But then removing it would cause other problems as well, including a
segfault!</p>
<p>It was not only one compiler that dumped core. Both dumped core with other
behaviour, depending on what changes in code were made, and the optimiser being
on or off. <code>clang</code> in macOS also dumped core!</p>
<p>The <a href="https://github.com/ioccc-src/winner/blob/master/1986/marshall/marshall.c">marshall.c</a> has the original fix
for <code>clang</code>, which works with some compilers, depending on the optimiser. Below
we refer to the <a href="https://github.com/ioccc-src/winner/blob/master/1986/marshall/marshall.alt.c">alternate code
marshall.alt.c</a>.</p>
<h2 id="the-conflicting-compiler-problems">The conflicting compiler problems:</h2>
<p>Below we describe the conflicting options that resulted in the need to modify
the original code.</p>
<h3 id="linux">Linux</h3>
<p>With the optimiser disabled <code>gcc</code> compiled the code to enter an infinite loop.
If the optimiser was enabled it worked fine, but if the optimiser is enabled
<code>clang</code> generates code that first prints the text twice (when it should print it
only once) and then immediately dumps core!</p>
<p>But then there’s that infinite loop. What happens if we fix it?</p>
<p>Once the loop is removed, if we compile with <code>clang</code> and the optimiser is disabled
all is okay. If however we compile with <code>gcc</code> and the optimiser is disabled the
string is printed once and then the program dumps core! Why is this? It is
because of the call to the <code>_exit(2)</code> syscall (see below).</p>
<p><code>clang</code> works fine with the loop removed if the optimiser is disabled. Once we
enable it, though, it will generate code that prints the string twice and
dumps core, just like before!</p>
<div id="exit">
<h3 id="what-about-the-call-to-the-_exit2-syscall">What about the call to the <code>_exit(2)</code> syscall?</h3>
</div>
<p>The call <em>was</em>:</p>
<pre><code> _exit(argv[(int)*argc-2/cc[1*(int)*argc]|-1&lt;&lt;4]);</code></pre>
<p>In the fixed code, these variables are simply commented out so the code does
<code>_exit(1)</code>.</p>
<h3 id="macos">macOS</h3>
<p>Now as for macOS, <em>another problem</em> existed!</p>
<p>If the code that resulted in an infinite loop is <em>NOT</em> commented out <em>AND</em> the
optimiser is enabled it works fine; but if it [the optimiser] is disabled, it
prints out the string and then enters that infinite loop!</p>
<p>After we fix the infinite loop issue, if we change the call to the <code>_exit(2)</code>
syscall in macOS and disable the optimiser we might get something like:</p>
<pre><code> $ ./marshall
choo choo
Segmentation fault: 11</code></pre>
<p>Observe how it doesn’t print it twice. But of course it segfaults so it’s not
right either.</p>
<p>If the optimiser is enabled, however, we will see that it works fine before the
change to the call to the <code>_exit(2)</code> syscall.</p>
<h2 id="summary">Summary</h2>
<p>And that is the tale of a little <del>engine</del> train that
could…eventually! Or perhaps it’s the compilers, optimisers and OSes that
eventually could?</p>
<p>Whichever you wish it to be, it now works with both <code>clang</code> and <code>cc</code>. Choo choo!</p>
<hr style="width:10%;text-align:left;margin-left:0">
<p>Jump to: <a href="#">top</a></p>
<!--
Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
You are free to share and adapt this file under the terms of this license:
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
For more information, see:
https://creativecommons.org/licenses/by-sa/4.0/
-->
<!-- AFTER: last line of markdown file: 1986/marshall/compilers.md -->
<!-- END: this line ends content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
<!-- START: this line starts content from: inc/after-content.default.html -->
</div>
<!-- END: this line ends content from: inc/after-content.default.html -->
<!-- START: this line starts content from: inc/footer.default.html -->
<!--
Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
You are free to share and adapt this file under the terms of this license:
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
For more information, see:
https://creativecommons.org/licenses/by-sa/4.0/
-->
<div class="footer">
<div id="copyright"><h3>Copyright &copy; 1984-2024 by Landon Curt Noll:
<a href="https://creativecommons.org/faq/#what-does-some-rights-reserved-mean"
target="_blank"
rel="license noopener noreferrer">Some Rights Reserved</a></h3>
<p>
This work is <b>licensed by Landon Curt Noll</b> under
<b><a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1"
target="_blank"
rel="license noopener noreferrer"
style="display:inline-block;">CC BY-SA 4.0</a></b>.
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
src="../../png/cc.png"
alt="cc inside circle symbol">
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
src="../../png/by.png"
alt="person inside circle symbol">
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
src="../../png/sa.png"
alt="arrow looping back on itself inside circle symbol"><br>
You should <b>carefully review</b> the
<b><a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en"
target="_blank"
rel="license noopener noreferrer">CC BY-SA 4.0 LEGAL CODE</a></b>
before using the licensed material.<br>
You may wish to review the
<b><a href="../../license.html"
target="_blank"
rel="license noopener noreferrer">highlights of some of the key features and terms</a></b>
of <b>CC BY-SA 4.0</b>.<br>
</p>
</div>
<div id="coda"><h3>Coda</h3>
<p>
<a href="https://validator.w3.org/nu/?doc=https%3A%2F%2Fwww.ioccc.org%2F1986%2Fmarshall%2Fcompilers.html" rel="nofollow">Nu HTML check this web page</a><br>
<a href="#top">Jump to top</a> <a href="#content">Jump to Content</a>
</p>
</div>
</div>
<!-- END: this line ends content from: inc/footer.default.html -->
<!-- START: this line starts content from: inc/bottom.default.html -->
</body>
</html>
<!-- END: this line ends content from: inc/bottom.default.html -->