[llvm-dev] [RFC] Polly Status and Integration

Sebastian Pop via llvm-dev llvm-dev at lists.llvm.org
Wed Sep 13 06:39:14 PDT 2017

Hi Gerolf,

On Tue, Sep 12, 2017 at 10:26 PM, Gerolf Hoflehner via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Are you saying the LLVM Dependence Analysis is incorrect or do you actually mean less conservative (or "more accurate" or something like that)?

Yes, the LLVM dependence analysis is broken from day one, by design,
due to a misunderstanding of the meaning of GEPs:

Loop interchange and any other pass that relies on the current llvm
dependence analysis may generate wrong code.
See https://reviews.llvm.org/D35430

Another point, the MIV test in the llvm depednence analysis is not
implemented, and so the scope of the llvm dependence analysis is
rather narrow: i.e., it would not be able to solve the loop
interchange in spec2000/swim.


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