[llvm-dev] How to get information about data dependencies? (original) (raw)

Michael Kruse via llvm-dev llvm-dev at lists.llvm.org
Mon Jul 20 14🔞07 PDT 2020

Am Mi., 15. Juli 2020 um 14:18 Uhr schrieb David Greene via llvm-dev <llvm-dev at lists.llvm.org>:

Stefanos Baziotis via llvm-dev <llvm-dev at lists.llvm.org> writes:

> Well... I tried that and it doesn't seem to be very useful > unfortunately. The C/C++ way that arrays are defined is probably why > DA is not that useful. Namely that a row can alias with another row in > 2D arrays. The theory behind DA is quite powerful if we knew that they > don't alias. Right now, it just gives up. Note that the situation is very different in flang, where good dependence analysis becomes much more critical.

There was an RFC on the mailing list to support a GetElementPtr with dynamic array sizes: http://lists.llvm.org/pipermail/llvm-dev/2019-July/134063.html

We also had a discussion whether A[i][j] can be lowered to a GetElementPtr with inrange keyword for the subscripts, including for statically sized arrays.

Michael

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