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

Finkel, Hal J. via llvm-dev
2018-12-12T17:11:04Z

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