[llvm-dev] RFC: LoopIDs are not identifiers (and better loop-parallel metadata) (original) (raw)

Finkel, Hal J. via llvm-dev llvm-dev at lists.llvm.org
Wed Dec 12 09:11:04 PST 2018

On 12/12/18 10:29 AM, Michael Kruse wrote:

Am Mi., 12. Dez. 2018 um 10:10 Uhr schrieb Finkel, Hal J. <hfinkel at anl.gov>:

As we have seen, there are other reasons for loops to have identical LoopIDs. With patches [3,4], llvm.loop metadata can be collapsed (unlike access groups), thus the 'distinct' is not necessary anymore. Unfortunately, there is code in LLVM (and maybe elsewhere) that depends on LoopIDs' first item, i.e. we cannot get rid of it that easily. I don't think it's worth changing this first element, unless we have some other reason to do so. Would it be worthwhile to update the metadata uniquing algorithm to consider shallow self-references?

What benefit would that bring?

 -Hal

Michael

-- Hal Finkel Lead, Compiler Technology and Programming Languages Leadership Computing Facility Argonne National Laboratory

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