[LLVMdev] Alias analysis result

[Welson Sun]

OK, that's actually quite straightforward, I will just share it here:

1. In "my_pass", you need this:
    void getAnalysisUsage(AnalysisUsage &Info) const {
      Info.addRequired<AliasAnalysis>();
      Info.setPreservesAll();
    }

2. In the main() function, add this:
  PassRegistry &Registry = *PassRegistry::getPassRegistry();
  initializeBasicAliasAnalysisPass(Registry);

  You can replace "BasicAliasAnalysis" with other alias analysis classes,
refer to llvm/InitializePasses.h for the list.

3. Finally, anywhere in your code, you can write this:
    AliasAnalysis &AA = getAnalysis<AliasAnalysis>();


Hope this helps,
Welson

On Wed, Sep 19, 2012 at 12:59 AM, Duncan Sands <baldrick at free.fr> wrote:

> Hi Welson,
>
>
>  In case "my_pass" is compiled into a standalone executable, how can I run
>> the
>> specific alias analysis in the code?
>>
>
> I suggest you work out what passing -basic-aa to opt does, how it works,
> and do
> the same in your code.
>
> Ciao, Duncan.
>
>
>> Thanks
>>
>> On Thu, Mar 8, 2012 at 8:55 AM, Duncan Sands <baldrick at free.fr
>> <mailto:baldrick at free.fr>> wrote:
>>
>>     Hi,
>>
>>      > That's the reason I have defined getAnalysisUsage method. Isn't
>> that the
>>      > right way to do it?
>>
>>     no, that gives you access to whatever alias analysis has been
>> computed, but
>>     it doesn't specify what kind of alias analysis should be computed
>> (there are
>>     several).  Try something like this:
>>         opt -load=my_pass.so -basic-aa -run_my_pass ...
>>     Ciao, Duncan.
>>     ______________________________**_________________
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>>
>>
>>
>>
>> --
>> Welson
>>
>> Phone: (408) 418-8385
>> Email: welson.sun at gmail.com <mailto:welson.sun at gmail.com>
>>
>>
>>
>


-- 
Welson

Phone: (408) 418-8385
Email:  welson.sun at gmail.com
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