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On 6/22/11 5:34 AM, Andreas Wilhelm wrote:
<blockquote cite="mid:87CB53AB-7258-4CB7-AF7F-8EF8E54F668D@gmx.com"
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Hello,
<div><br>
</div>
<div>I'm looking for a way to identify dependencies of
function-pairs (memory-dependency, control-dependency...) in
order to parallelize them.</div>
<div>For aliasing problems I use the DataStructureAnalysis.</div>
</blockquote>
<br>
I'm assuming that this is the DSA analysis in the poolalloc module.
Be forewarned that:<br>
<br>
1) DSA works with LLVM 2.7; I don't believe it works with LLVM
mainline yet.<br>
2) The alias analysis interface to DSA hasn't been maintained in
awhile; you'll need to examine the DSGraphs directly.<br>
<br>
<br>
<blockquote cite="mid:87CB53AB-7258-4CB7-AF7F-8EF8E54F668D@gmx.com"
type="cite">
<div> To solve simple memory- and control-dependency problems I
want to use</div>
<div>memdep. But unfortunately I even fail with following simple
C++ example...</div>
<div><br>
</div>
<div><font class="Apple-style-span" face="Verdana">int a( int n) {
return n; }</font></div>
<div><font class="Apple-style-span" face="Verdana">int b( int n) {
return n; }</font></div>
<div><font class="Apple-style-span" face="Verdana">int c( int n) {
return n; }</font></div>
<div><font class="Apple-style-span" face="Verdana"><br>
</font></div>
<div><font class="Apple-style-span" face="Verdana">int main( int
argc, char** argv) {</font></div>
<div><font class="Apple-style-span" face="Verdana"><br>
</font></div>
<div><font class="Apple-style-span" face="Verdana"> int x = a(
argc);</font></div>
<div><font class="Apple-style-span" face="Verdana"> b( 0);</font></div>
<div><font class="Apple-style-span" face="Verdana"><span
class="Apple-tab-span" style="white-space: pre;"> </span></font></div>
<div><font class="Apple-style-span" face="Verdana"> <span
class="Apple-tab-span" style="white-space: pre;">i</span>f (
x)</font></div>
<div><font class="Apple-style-span" face="Verdana"> x = 0;</font></div>
<div><font class="Apple-style-span" face="Verdana"><span
class="Apple-tab-span" style="white-space: pre;"><br>
</span></font></div>
<div><font class="Apple-style-span" face="Verdana"> return ( c(
x));<span class="Apple-tab-span" style="white-space: pre;"> </span></font></div>
<div><font class="Apple-style-span" face="Verdana">}</font></div>
<div><font class="Apple-style-span" face="Verdana"><br>
</font></div>
<div><font class="Apple-style-span" face="Verdana">... The result
of memdep shows a dependency between the callsite of b() and
the call of a(). Why?</font></div>
<div><font class="Apple-style-span" face="Verdana">Moreover I want
to get the dependency between the call to c() and the result
of a(). How can I obtain this?</font></div>
<div><font class="Apple-style-span" face="Verdana"><br>
</font></div>
</blockquote>
<br>
I can't comment on what memdep does as I've never used it; others
more knowledgeable will have to comment.<br>
<br>
Regarding your last question on following the def of x to the use in
c(x), that looks like a simple data-flow analysis problem; just
follow the def-use chain of the SSA variables from the call of a()
to the call of c() in main().<br>
<br>
-- John T.<br>
<br>
<blockquote cite="mid:87CB53AB-7258-4CB7-AF7F-8EF8E54F668D@gmx.com"
type="cite">
<div><font class="Apple-style-span" face="Verdana">Thanks in
advance,</font></div>
<div><font class="Apple-style-span" face="Verdana">Andreas</font></div>
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