<span style="font-size:13px;color:rgb(34,34,34);font-family:arial,sans-serif;text-align:left;background-color:rgb(255,255,255)">I perform the Instcombine pass over </span><span style="font-size:13px;color:rgb(34,34,34);font-family:arial,sans-serif;text-align:left;background-color:rgb(255,255,255)">Rijndael </span><span style="font-size:13px;color:rgb(34,34,34);font-family:arial,sans-serif;text-align:left;background-color:rgb(255,255,255)">benchmark from Mibench ( suite of benchmarks). For compile, I use "-Instcount" for counting the instructions. Comparing the bench without transformation </span><span style="font-size:13px;color:rgb(34,34,34);font-family:arial,sans-serif;text-align:left;background-color:rgb(255,255,255)">with </span><span style="font-size:13px;color:rgb(34,34,34);font-family:arial,sans-serif;text-align:left;background-color:rgb(255,255,255)">the bench </span><span style="font-size:13px;color:rgb(34,34,34);font-family:arial,sans-serif;text-align:left;background-color:rgb(255,255,255)">transformed by instcombine, I perceived a 10% of increase in the number of instructions. This is possible?</span><br>

<br><div class="gmail_quote">On Wed, Jun 27, 2012 at 4:57 AM, Duncan Sands <span dir="ltr"><<a href="mailto:baldrick@free.fr" target="_blank">baldrick@free.fr</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">

Hi Rafael,<br>
<div class="im"><br>
> Can  the Instcombine pass  increase the number of instructions of a block?<br>
<br>
</div>while it usually doesn't, in theory it can increase the number of LLVM IR<br>
instructions.  I don't recall an example off the top of my head, but the<br>
usual situation is that replacing some instruction I with a pair J, K<br>
results in better code generation.  There are a small number of cases like<br>
this.<br>
<br>
Ciao, Duncan.<br>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><font><b><i>Rafael Parizi</i></b></font><br><br><br><br>