[LLVMdev] BasicAA unable to analyze recursive PHI nodes

Sanjoy Das
Wed, 10 Jun 2015 22:52:07 -0000

Sorry for missing this the first time around, but I think -scev-aa
does what you want.  I've commented on the phabricator review.

On Wed, Jun 10, 2015 at 3:32 PM, Tobias Edler von Koch
<tobias at codeaurora.org> wrote:
> On Tue, 2 Jun 2015 11:32:13 -0500 Tobias Edler von Koch
> <tobias at codeaurora.org> wrote:
>
>> Hi all,
>>
>> I came across the following limitation in our BasicAliasAnalysis. This
>> happens with the following IR pattern:
>>
>>   %x = phi [ %incptr, ... ] [ %var, ... ]
>>   %incptr = getelementptr %x, 1
>>
>> We will basically always return MayAlias for %x and any other value
>> because aliasPHI recurses on the first value and gives up.
>
> Patch now posted as http://reviews.llvm.org/D10368
>
> Tobias
>
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