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some minor edits, link to Passes.html, make one point

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I forgot about yesterday.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43350 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2007-10-25 17:52:39 +00:00
parent 89a354d7fa
commit 7271423a99
1 changed files with 25 additions and 2 deletions
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27
docs/tutorial/LangImpl4.html
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@ -252,8 +252,9 @@ entry:
add from the program.</p>
<p>LLVM provides a wide variety of optimizations that can be used in certain
circumstances. Unfortunately we don't have a good centralized description of
what every pass does, but you can check out the ones that <tt>llvm-gcc</tt> or
circumstances. Some <a href="../Passes.html">documentation about the various
passes</a> is available, but it isn't very complete. Another good source of
ideas is to look at the passes that <tt>llvm-gcc</tt> or
<tt>llvm-ld</tt> run to get started. The "<tt>opt</tt>" tool allows you to
experiment with passes from the command line, so you can see if they do
anything.</p>
@ -410,6 +411,7 @@ declare double @cos(double)
ready&gt; <b>sin(1.0);</b>
<em>Evaluated to 0.841471</em>
ready&gt; <b>def foo(x) sin(x)*sin(x) + cos(x)*cos(x);</b>
Read function definition:
define double @foo(double %x) {
@ -444,6 +446,27 @@ tables, for example), allows you to dynamically decide on the fly based on the
function name, and even allows you to have the JIT abort itself if any lazy
compilation is attempted.</p>
<p>One interesting application of this is that we can now extend the language
by writing arbitrary C++ code to implement operations. For example, if we add:
</p>
<div class="doc_code">
<pre>
/// putchard - putchar that takes a double and returns 0.
extern "C"
double putchard(double X) {
putchar((char)X);
return 0;
}
</pre>
</div>
<p>Now we can produce simple output to the console by using things like:
"<tt>extern putchard(x); putchard(120);</tt>", which prints a lowercase 'x' on
the console (120 is the ascii code for 'x'). Similar code could be used to
implement file I/O, console input, and many other capabilities in
Kaleidoscope.</p>
<p>This completes the JIT and optimizer chapter of the Kaleidoscope tutorial. At
this point, we can compile a non-Turing-complete programming language, optimize
and JIT compile it in a user-driven way. Next up we'll look into <a