[LLVMdev] BasicAA unable to analyze recursive PHI nodes

Tobias Edler von Koch
Wed, 10 Jun 2015 22:32:23 -0000

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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