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More cleanups. 

llvm-svn: 68718
This commit is contained in:
Ted Kremenek 2009-04-09 18:17:39 +00:00
parent df0d9070b8
commit 8918025272
1 changed files with 23 additions and 13 deletions
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36
clang/docs/PTHInternals.html
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@ -38,17 +38,26 @@ interface for using PTH and then briefly elaborates on their design and
implementation.</p>
<h2>Using Pretokenized Headers (High-level Interface)</h2>
<h2>Using Pretokenized Headers with <tt>clang</tt></h2>
<p>The high-level interface to generate a PTH file is the same as GCC's:</p>
<p>The high-level <tt>clang</tt> driver supports an interface to use PTH files
that is similar to GCC's interface for precompiled headers.</p>
<h3>Generating a PTH File</h3>
<p>To generate a PTH file using <tt>clang</tt>, one invokes <tt>clang</tt> using
the <tt>-x <b>lang-header</b></tt> option. This mirrors the interface in GCC for
generating PCH files:</p>
<pre>
$ gcc -x c-header test.h -o test.h.gch
$ clang -x c-header test.h -o test.h.pth
</pre>
<p>A PTH file can then be used as a prefix header when a <tt>-include</tt>
option is passed to <tt>clang</tt>:</p>
<h3>Using a PTH File</h3>
<p>A PTH file can then be used as a prefix header when a
<b><tt>-include</tt></b> option is passed to <tt>clang</tt>:</p>
<pre>
$ clang -include test.h test.c -o test
@ -74,19 +83,19 @@ for headers that are directly included within a source file. For example:</p>
<tt>test.h</tt> since <tt>test.h</tt> was included directly in the source file
and not specified on the command line using <tt>-include</tt>.</p>
<h2>Using Pretokenized Headers (Low-level Interface)</h2>
<h2>Using Pretokenized Headers with <tt>clang-cc</tt> (Low-level Interface)</h2>
<p>The low-level Clang compiler tool, <tt>clang-cc</tt>, supports three command
line options for generating and using PTH files.<p>
<p>To generate PTH files using <tt>clang-cc</tt>, use the option <tt>-emit-pth</tt>:
<pre>
$ clang-cc test.h -emit-pth -o test.h.pth
</pre>
<p>To generate PTH files using <tt>clang-cc</tt>, use the option
<b><tt>-emit-pth</tt></b>:
<pre> $ clang-cc test.h -emit-pth -o test.h.pth </pre>
<p>This option is transparently used by <tt>clang</tt> when generating PTH
files. Similarly, PTH files can be used as prefix headers using the <tt>-include-pth</tt> option:</p>
files. Similarly, PTH files can be used as prefix headers using the
<b><tt>-include-pth</tt></b> option:</p>
<pre>
$ clang-cc -include-pth test.h.pth test.c -o test.s
@ -96,7 +105,8 @@ files. Similarly, PTH files can be used as prefix headers using the <tt>-includ
(or &quot;content&quot; cache) of the source included by the original header
file. This means that the contents of the PTH file are searched as substitutes
for <em>any</em> source files that are used by <tt>clang-cc</tt> to process a
source file. This is done by specifying the <tt>-token-cache</tt> option:</p>
source file. This is done by specifying the <b><tt>-token-cache</tt></b>
option:</p>
<pre>
$ cat test.h
@ -173,7 +183,7 @@ also modifies those pages in memory, incurring the copy-on-write costs. The
read-only nature of PTH can greatly reduce memory pressure for builds involving
multiple cores, thus improving overall scalability.</p></li>
<li><p><em>Fast generation<em>: PTH files can be generated in a small fraction
<li><p><em>Fast generation</em>: PTH files can be generated in a small fraction
of the time needed to generate GCC's PCH files. Since PTH/PCH generation is a
serial operation that typically blocks progress during a build, faster
generation time leads to improved processor utilization with parallel builds on