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<DIV><FONT color=#1b0000 size=2 face=Verdana>Than you John, It's very nice of
you.</FONT></DIV>
<DIV><FONT color=#1b0000 size=2 face=Verdana></FONT> </DIV>
<DIV><FONT color=#1b0000 size=2 face=Verdana>Best Regards</FONT></DIV>
<DIV><FONT color=#1b0000></FONT> </DIV>
<DIV><FONT color=#1b0000 size=2 face=Verdana>2010-11-30 </FONT></DIV><FONT
color=#1b0000 size=2 face=Verdana>
<HR style="WIDTH: 100px" align=left color=#b5c4df SIZE=1>
</FONT>
<DIV><FONT size=2 face=Verdana><FONT
color=#1b0000><SPAN>-Wei</SPAN></FONT></FONT></DIV>
<HR color=#b5c4df SIZE=1>
<DIV><FONT size=2 face=Verdana><STRONG>发件人：</STRONG> John McCall </FONT></DIV>
<DIV><FONT size=2 face=Verdana><STRONG>发送时间：</STRONG> 2010-11-30 09:26:17
</FONT></DIV>
<DIV><FONT size=2 face=Verdana><STRONG>收件人：</STRONG> huwei8717 </FONT></DIV>
<DIV><FONT size=2 face=Verdana><STRONG>抄送：</STRONG> llvmdev </FONT></DIV>
<DIV><FONT size=2 face=Verdana><STRONG>主题：</STRONG> Re: [LLVMdev] the called
function equal NULL </FONT></DIV>
<DIV><FONT size=2 face=Verdana></FONT> </DIV>
<DIV><FONT size=2 face=Verdana><BR>
<DIV>
<DIV>On Nov 29, 2010, at 5:22 PM, huwei8717 wrote:</DIV><BR
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<DIV><FONT size=2>Hi,</FONT></DIV>
<DIV> </DIV>
<DIV style="TEXT-INDENT: 2em">I have a llvm-pass in hand written by other
people. There are following statements that I couldn't understand:</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV
style="TEXT-INDENT: 2em">-------------------------------program----------------------------------------------------</DIV>
<DIV style="TEXT-INDENT: 2em">
<DIV>...</DIV>
<DIV>if (isa<CallInst>(inst) || isa<InvokeInst>(inst)) {</DIV>
<DIV> const CallSite cs(inst);</DIV>
<DIV> if (cs.getCalledFunction() == NULL)</DIV>
<DIV> return dealAtIndirectCall(cs);</DIV>
<DIV> else</DIV>
<DIV> return dealAtDirectCall(cs);</DIV>
<DIV>}</DIV></DIV>
<DIV style="TEXT-INDENT: 2em">...</DIV>
<DIV
style="TEXT-INDENT: 2em">-------------------------------------------------------------------------------------------</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 2em">My question is:</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 2em">When does the called function equal NULL,
could you give an example? I mean what kind of call in source code could
change to this case in llvm-IR, could you give an
example?</DIV></DIV></SPAN></BLOCKQUOTE><BR></DIV>
<DIV>A call to a value of function-pointer type, e.g.</DIV>
<DIV> void callit(void (*f)()) { f(); }</DIV><BR>
<DIV>Virtual calls in C++ would also have no known called function.</DIV>
<DIV><BR></DIV>
<DIV>John.</DIV></FONT></DIV></BODY></HTML>