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<div class="moz-cite-prefix">On 4/15/2018 11:44 AM, Mustakimur
Khandaker via llvm-dev wrote:<br>
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<blockquote type="cite"
cite="mid:BY2PR05MB710BBF391709E06B7DBEF1AEFB10@BY2PR05MB710.namprd05.prod.outlook.com">
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<div>Hi </div>
<div>I have this simple c code for which I would like to use for
alias analysis. </div>
<div><br>
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0px;">
<div>#include <stdio.h></div>
<div>#include <stdlib.h></div>
<div><br>
</div>
<div>static int (*fp) (void); </div>
<div>void ind_call (int (*compr)(void)){ </div>
<div> fp = compr; </div>
<div> fp(); </div>
<div>} </div>
<div>int hello(void){ </div>
<div> return printf("hello world\n"); </div>
<div>} </div>
<div>int main(){ </div>
<div> ind_call(hello); </div>
<div> return 0; </div>
<div>} </div>
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<div><br>
</div>
<div>So, I do the following: </div>
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0px;">
<div>bin/opt -basicaa -cfl-anders-aa -print-alias-sets
bin/test/test.bc </div>
</blockquote>
<div><br>
</div>
<div>I get the following result: </div>
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0px;">
<div>Alias sets for function 'ind_call': </div>
<div>Alias Set Tracker: 2 alias sets for 2 pointer values. </div>
<div> AliasSet[0x91a5820, 1] must alias, Mod/Ref Pointers:
(i32 ()** %compr.addr, 8) </div>
<div> AliasSet[0x91a58c0, 2] may alias, Mod/Ref Pointers:
(i32 ()** @fp, 8) </div>
<div> 1 Unknown instructions: i32 %call <br>
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<br>
LLVM's alias analysis is not very smart; it depends on other
optimization passes to produce reasonable results. You should at
least run mem2reg before trying to do any alias analysis queries.<br>
<br>
-Eli<br>
<p><br>
</p>
<pre class="moz-signature" cols="72">--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project</pre>
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