[llvm-commits] CVS: llvm/docs/FAQ.html
Misha Brukman
brukman at cs.uiuc.edu
Thu Nov 6 15:56:02 PST 2003
Changes in directory llvm/docs:
FAQ.html updated: 1.9 -> 1.10
---
Log message:
* Added a "contents"-like list of questions at the beginning of the file
* Use stylsheets. Really, people, work with me here.
* Stop using those silly <dl> and <dt> and whatever else tags
* Close tags
---
Diffs of the changes: (+311 -207)
Index: llvm/docs/FAQ.html
diff -u llvm/docs/FAQ.html:1.9 llvm/docs/FAQ.html:1.10
--- llvm/docs/FAQ.html:1.9 Wed Oct 29 19:16:18 2003
+++ llvm/docs/FAQ.html Thu Nov 6 15:55:44 2003
@@ -1,214 +1,318 @@
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
+ "http://www.w3.org/TR/html4/strict.dtd">
+<html>
+<head>
+ <title>LLVM: Frequently Asked Questions</title>
+ <style>
+ @import url("llvm.css");
+ .question { font-weight: bold }
+ .answer { margin-left: 2em }
+ </style>
+</head>
+<body>
+
+<div class="doc_title">
+ LLVM: Frequently Asked Questions
+</div>
+
+<ol>
+ <li><a href="#license">License</a>
+ <ol>
+ <li>Why are the LLVM source code and the front-end distributed under different
+ licenses?</li>
+ <li>Does the University of Illinois Open Source License really qualify as an
+ "open source" license?</li>
+ <li>Can I modify LLVM source code and redistribute the modified source?</li>
+ <li>Can I modify LLVM source code and redistribute binaries or other tools
+ based on it, without redistributing the source?</li>
+ </ol></li>
+
+ <li><a href="#source">Source code</a>
+ <ol>
+ <li>In what language is LLVM written?</li>
+ <li>How portable is the LLVM source code?</li>
+ </ol></li>
+
+ <li><a href="#build">Build Problems</a>
+ <ol>
+ <li>When I run configure, it finds the wrong C compiler.</li>
+ <li>I compile the code, and I get some error about <tt>/localhome</tt>.</li>
+ <li>The <tt>configure</tt> script finds the right C compiler, but it uses the
+ LLVM linker from a previous build. What do I do?</li>
+ <li>When creating a dynamic library, I get a strange GLIBC error.</li>
+ <li>I've updated my source tree from CVS, and now my build is trying to use a
+ file/directory that doesn't exist.</li>
+ <li>I've modified a Makefile in my source tree, but my build tree keeps using
+ the old version. What do I do?</li>
+ <li>I've upgraded to a new version of LLVM, and I get strange build
+ errors.</li>
+ <li>I've built LLVM and am testing it, but the tests freeze.</li>
+ <li>Why do test results differ when I perform different types of builds?</li>
+ </ol></li>
+</ol>
+
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="license">License</a>
+</div>
+<!-- *********************************************************************** -->
+
+<div class="question">
+<p>Why are the LLVM source code and the front-end distributed under different
+licenses?</p>
+</div>
+
+<div class="answer">
+<p>The C/C++ front-ends are based on GCC and must be distributed under the GPL.
+Our aim is to distribute LLVM source code under a <em>much less restrictive</em>
+license, in particular one that does not compel users who distribute tools based
+on modifying the source to redistribute the modified source code as well.</p>
+</div>
+
+<div class="question">
+<p>Does the University of Illinois Open Source License really qualify as an
+"open source" license?</p>
+</div>
+
+<div class="answer">
+<p>Yes, the license is <a
+href="http://www.opensource.org/licenses/UoI-NCSA.php">certified</a> by the Open
+Source Initiative (OSI).</p>
+</div>
+
+<div class="question">
+<p>Can I modify LLVM source code and redistribute the modified source?</p>
+</div>
+
+<div class="answer">
+<p>Yes. The modified source distribution must retain the copyright notice and
+follow the three bulletted conditions listed in the <a
+href="http://llvm.cs.uiuc.edu/releases/1.0/LICENSE.TXT">LLVM license</a>.</p>
+</div>
+
+<div class="question">
+<p>Can I modify LLVM source code and redistribute binaries or other tools based
+on it, without redistributing the source?</p>
+</div>
+
+<div class="answer">
+<p>Yes, this is why we distribute LLVM under a less restrictive license than
+GPL, as explained in the first question above.</p>
+</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="source">Source Code</a>
+</div>
+<!-- *********************************************************************** -->
+
+<div class="question">
+<p>In what language is LLVM written?</p>
+</div>
+
+<div class="answer">
+<p>All of the LLVM tools and libraries are written in C++ with extensive use of
+the STL.</p>
+</div>
+
+<div class="question">
+<p>How portable is the LLVM source code?</p>
+</div>
+
+<div class="answer">
+<p>The LLVM source code should be portable to most modern UNIX-like operating
+systems. Most of the code is written in standard C++ with operating system
+services abstracted to a support library. The tools required to build and test
+LLVM have been ported to a plethora of platforms.</p>
+
+<p>Some porting problems may exist in the following areas:</p>
+
+<ul>
+
+ <li>The GCC front end code is not as portable as the LLVM suite, so it may not
+ compile as well on unsupported platforms.</li>
+
+ <li>The Python test classes are more UNIX-centric than they should be, so
+ porting to non-UNIX like platforms (i.e. Windows, MacOS 9) will require some
+ effort.</li>
+
+ <li>The LLVM build system relies heavily on UNIX shell tools, like the Bourne
+ Shell and sed. Porting to systems without these tools (MacOS 9, Plan 9) will
+ require more effort.</li>
+
+</ul>
+
+</div>
+
+<!-- *********************************************************************** -->
+<div class="doc_section">
+ <a name="build">Build Problems</a>
+</div>
+<!-- *********************************************************************** -->
+
+<div class="question">
+<p>When I run configure, it finds the wrong C compiler.</p>
+</div>
+
+<div class="answer">
+
+<p>The <tt>configure</tt> script attempts to locate first <tt>gcc</tt> and then
+<tt>cc</tt>, unless it finds compiler paths set in <tt>CC</tt> and <tt>CXX</tt>
+for the C and C++ compiler, respectively.</p>
+
+<p>If <tt>configure</tt> finds the wrong compiler, either adjust your
+<tt>PATH</tt> environment variable or set <tt>CC</tt> and <tt>CXX</tt>
+explicitly.</p>
+
+</div>
+
+<div class="question">
+<p>I compile the code, and I get some error about <tt>/localhome</tt>.</p>
+</div>
+
+<div class="answer">
+
+<p>There are several possible causes for this. The first is that you didn't set
+a pathname properly when using <tt>configure</tt>, and it defaulted to a
+pathname that we use on our research machines.</p>
+
+<p>Another possibility is that we hardcoded a path in our Makefiles. If you see
+this, please email the LLVM bug mailing list with the name of the offending
+Makefile and a description of what is wrong with it.</p>
+
+</div>
+
+<div class="question">
+<p>The <tt>configure</tt> script finds the right C compiler, but it uses the
+LLVM linker from a previous build. What do I do?</p>
+</div>
+
+<div class="answer">
+<p>The <tt>configure</tt> script uses the <tt>PATH</tt> to find executables, so
+if it's grabbing the wrong linker/assembler/etc, there are two ways to fix
+it:</p>
+
+<ol>
+
+ <li><p>Adjust your <tt>PATH</tt> environment variable so that the correct
+ program appears first in the <tt>PATH</tt>. This may work, but may not be
+ convenient when you want them <i>first</i> in your path for other
+ work.</p></li>
+
+ <li><p>Run <tt>configure</tt> with an alternative <tt>PATH</tt> that is
+ correct. In a Borne compatible shell, the syntax would be:</p>
+
+ <p><tt>PATH=<the path without the bad program> ./configure ...</tt></p>
+
+ <p>This is still somewhat inconvenient, but it allows <tt>configure</tt>
+ to do its work without having to adjust your <tt>PATH</tt>
+ permanently.</p></li>
+
+</ol>
+
+</div>
+
+<div class="question">
+<p>When creating a dynamic library, I get a strange GLIBC error.</p>
+</div>
+
+<div class="answer">
+<p>Under some operating systems (i.e. Linux), libtool does not work correctly if
+GCC was compiled with the --disable-shared option. To work around this, install
+your own version of GCC that has shared libraries enabled by default.</p>
+</div>
+
+<div class="question">
+<p>I've updated my source tree from CVS, and now my build is trying to use a
+file/directory that doesn't exist.</p>
+</div>
+
+<div class="answer">
+<p>You need to re-run configure in your object directory. When new Makefiles
+are added to the source tree, they have to be copied over to the object tree in
+order to be used by the build.</p>
+</div>
+
+<div class="question">
+<p>I've modified a Makefile in my source tree, but my build tree keeps using the
+old version. What do I do?</p>
+</div>
+
+<div class="answer">
+
+<p>If the Makefile already exists in your object tree, you
+can just run the following command in the top level directory of your object
+tree:</p>
+
+<p><tt>./config.status <relative path to Makefile></tt><p>
+
+<p>If the Makefile is new, you will have to modify the configure script to copy
+it over.</p>
+
+</div>
+
+<div class="question">
+<p>I've upgraded to a new version of LLVM, and I get strange build errors.</p>
+</div>
+
+<div class="answer">
+
+<p>Sometimes, changes to the LLVM source code alters how the build system works.
+Changes in libtool, autoconf, or header file dependencies are especially prone
+to this sort of problem.</p>
+
+<p>The best thing to try is to remove the old files and re-build. In most
+cases, this takes care of the problem. To do this, just type <tt>make
+clean</tt> and then <tt>make</tt> in the directory that fails to build.</p>
+
+</div>
+
+<div class="question">
+<p>I've built LLVM and am testing it, but the tests freeze.</p>
+</div>
+
+<div class="answer">
+
+<p>This is most likely occurring because you built a profile or release
+(optimized) build of LLVM and have not specified the same information on the
+<tt>gmake</tt> command line.</p>
+
+<p>For example, if you built LLVM with the command:</p>
+
+<p><tt>gmake ENABLE_PROFILING=1</tt>
+
+<p>...then you must run the tests with the following commands:</p>
+
+<p><tt>cd llvm/test<br>gmake ENABLE_PROFILING=1</tt></p>
+
+</div>
+
+<div class="question">
+<p>Why do test results differ when I perform different types of builds?</p>
+</div>
+
+<div class="answer">
+
+<p>The LLVM test suite is dependent upon several features of the LLVM tools and
+libraries.</p>
+
+<p>First, the debugging assertions in code are not enabled in optimized or
+profiling builds. Hence, tests that used to fail may pass.</p>
+
+<p>Second, some tests may rely upon debugging options or behavior that is only
+available in the debug build. These tests will fail in an optimized or profile
+build.</p>
-<h1>
-<center>
-LLVM: Frequently Asked Questions
-</center>
-</h1>
+</div>
-<hr>
-
-<!--=====================================================================-->
-<h2>
-<a name="license">Licenses</a>
-</h2>
-<!--=====================================================================-->
-
-<dl compact>
- <dt> <b>Why are the LLVM source code and the front-end distributed
- under different licenses?</b>
- <dd>
- The C/C++ front-ends are based on GCC and must be distributed under
- the GPL. Our aim is to distribute LLVM source code under a <em>much
- less restrictive</em> license, in particular one that does not
- compel users who distribute tools based on modifying the source to
- redistribute the modified source code as well.
- <p>
- <dt><b>Does the University of Illinois Open Source License really qualify
- as an "open source" license?</b>
- <dd>Yes, the license is
- <a href="http://www.opensource.org/licenses/UoI-NCSA.php">certified</a>
- by the Open Source Initiative (OSI).
- <p>
- <dt> <b>Can I modify LLVM source code and redistribute the modified
- source?</b>
- <dd>
- Yes. The modified source distribution must retain the
- copyright notice and follow the three bulletted conditions listed in
- the <a href="http://llvm.cs.uiuc.edu/releases/1.0/LICENSE.TXT">LLVM license</a>.
- <p>
- <dt> <b>Can I modify LLVM source code and redistribute binaries or
- other tools based on it, without redistributing the source?</b>
- <dd>
- Yes, this is why we distribute LLVM under a less restrictive license
- than GPL, as explained in the first question above.
- <p>
-</dl>
-<hr>
-
-<!--=====================================================================-->
-<h2>
-<a name="source">Source Code</a>
-</h2>
-<!--=====================================================================-->
-
-<dl compact>
- <dt> <b>In what language is LLVM written?</b>
- <dd>
- All of the LLVM tools and libraries are written in C++ with extensive use
- of the STL.
- <p>
-
- <dt><b>How portable is the LLVM source code?</b>
- <dd>
- The LLVM source code should be portable to most modern UNIX-like operating
- systems. Most of the code is written in standard C++ with operating
- system services abstracted to a support library. The tools required to
- build and test LLVM have been ported to a plethora of platforms.
- <p>
- Some porting problems may exist in the following areas:
- <ul>
- <li>The GCC front end code is not as portable as the LLVM suite, so it
- may not compile as well on unsupported platforms.
-
- <p>
-
- <li>The Python test classes are more UNIX-centric than they should be,
- so porting to non-UNIX like platforms (i.e. Windows, MacOS 9) will
- require some effort.
- <p>
-
- <li>The LLVM build system relies heavily on UNIX shell tools, like the
- Bourne Shell and sed. Porting to systems without these tools (MacOS 9,
- Plan 9) will require more effort.
- </ul>
-</dl>
+<!-- *********************************************************************** -->
<hr>
-
-<!--=====================================================================-->
-<h2>
-<a name="build">Build Problems</a>
-</h2>
-<!--=====================================================================-->
-
-<dl compact>
- <dt><b>When I run configure, it finds the wrong C compiler.</b>
- <dd>
- The <tt>configure</tt> script attempts to locate first <tt>gcc</tt> and
- then <tt>cc</tt>, unless it finds compiler paths set in <tt>CC</tt> and
- <tt>CXX</tt> for the C and C++ compiler, respectively.
-
- If <tt>configure</tt> finds the wrong compiler, either adjust your
- <tt>PATH</tt> environment variable or set <tt>CC</tt> and <tt>CXX</tt>
- explicitly.
- <p>
-
- <dt><b>I compile the code, and I get some error about /localhome</b>.
- <dd>
- There are several possible causes for this. The first is that you
- didn't set a pathname properly when using <tt>configure</tt>, and it
- defaulted to a pathname that we use on our research machines.
- <p>
- Another possibility is that we hardcoded a path in our Makefiles. If
- you see this, please email the LLVM bug mailing list with the name of
- the offending Makefile and a description of what is wrong with it.
-
- <dt><b>The <tt>configure</tt> script finds the right C compiler, but it
- uses the LLVM linker from a previous build. What do I do?</b>
- <dd>
- The <tt>configure</tt> script uses the <tt>PATH</tt> to find
- executables, so if it's grabbing the wrong linker/assembler/etc, there
- are two ways to fix it:
- <ol>
- <li>Adjust your <tt>PATH</tt> environment variable so that the
- correct program appears first in the <tt>PATH</tt>. This may work,
- but may not be convenient when you want them <i>first</i> in your
- path for other work.
- <p>
-
- <li>Run <tt>configure</tt> with an alternative <tt>PATH</tt> that
- is correct. In a Borne compatible shell, the syntax would be:
- <p>
- <tt>PATH=<the path without the bad program> ./configure ...</tt>
- <p>
- This is still somewhat inconvenient, but it allows
- <tt>configure</tt> to do its work without having to adjust your
- <tt>PATH</tt> permanently.
- </ol>
-
- <dt><b>When creating a dynamic library, I get a strange GLIBC error.</b>
- <dd>
- Under some operating systems (i.e. Linux), libtool does not work correctly
- if GCC was compiled with the --disable-shared option. To work around this,
- install your own version of GCC that has shared libraries enabled by
- default.
- <p>
-
- <dt><b>I've updated my source tree from CVS, and now my build is trying to
- use a file/directory that doesn't exist.</b>
- <dd>
- You need to re-run configure in your object directory. When new Makefiles
- are added to the source tree, they have to be copied over to the object
- tree in order to be used by the build.
- <p>
-
- <dt><b>I've modified a Makefile in my source tree, but my build tree keeps
- using the old version. What do I do?</b>
- <dd>
- If the Makefile already exists in your object tree, you can just run the
- following command in the top level directory of your object tree:
- <p>
- <tt>./config.status <relative path to Makefile></tt>
- <p>
- If the Makefile is new, you will have to modify the configure script to copy
- it over.
- <p>
-
- <dt><b>I've upgraded to a new version of LLVM, and I get strange build
- errors.</b>
- <dd>
- Sometimes changes to the LLVM source code alters how the build system
- works. Changes in libtool, autoconf, or header file dependencies are
- especially prone to this sort of problem.
- <p>
- The best thing to try is to remove the old files and re-build. In most
- cases, this takes care of the problem. To do this, just type <tt>make
- clean</tt> and then <tt>make</tt> in the directory that fails to build.
- <p>
-
- <dt><b>I've built LLVM and am testing it, but the tests freeze.</b>
- <dd>
- This is most likely occurring because you built a profile or release
- (optimized) build of LLVM and have not specified the same information on
- the <tt>gmake</tt> command line.
- <p>
- For example, if you built LLVM with the command:
- <p>
- <tt>gmake ENABLE_PROFILING=1</tt>
- <p>
- ...then you must run the tests with the following commands:
- <p>
- <tt>cd llvm/test<br>gmake ENABLE_PROFILING=1</tt>
- <p>
-
- <dt><b>Why do test results differ when I perform different types of
- builds?</b>
- <dd>
- The LLVM test suite is dependent upon several features of the LLVM tools
- and libraries.
- <p>
- First, the debugging assertions in code are not enabled in optimized or
- profiling builds. Hence, tests that used to fail may pass.
- <p>
- Second, some tests may rely upon debugging options or behavior that is
- only available in the debug build. These tests will fail in an optimized
- or profile build.
-</dl>
-<hr>
-
-<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
-<br>
+<div class="doc_footer">
+ <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
+ <br>
+ Last modified: $Date: 2003/11/06 21:55:44 $
+</div>
</body>
</html>
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