[llvm-dev] Is a PHI use of another PHI in the same block valid?

[Krzysztof Parzyszek via llvm-dev]

On 2/26/2016 11:02 AM, Philip Reames via llvm-dev wrote:
>
> So, is this legal IR?  Or not?

I don't know if the IR spec mentions this case, but it simply makes no 
sense.  PHI nodes indicate values on entry to the block.  Their ordering 
in the IR only exists because instructions are arranged in an ordered 
list, but the relative ordering of PHIs has no meaning.

-Krzysztof

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