[llvm] r283612 - [InstCombine] Don't unpack arrays that are too large (part 2).

Sanjoy Das via llvm-commits llvm-commits at lists.llvm.org
Sun Oct 30 21:26:29 PDT 2016

Sorry, had lost track of this thread.

On 10/11/16, 8:49 AM, Davide Italiano wrote:
> On Mon, Oct 10, 2016 at 7:04 PM, Sanjoy Das
> <sanjoy at playingwithpointers.com>  wrote:
>> How about making the 1024 a cl::opt tunable parameter (also in
>> https://reviews.llvm.org/rL283599)?
>> -- Sanjoy
> I have no strong opinion about this. A quick (probably non-exaustive)
> search in lib/Transform/InstCombine/* shows that the only cl::opt is
> the one to enable/disable expensive combines, so adding
> threshold-based tunables doesn't seem quite common there.
> I'm fine with adding the new tunable but maybe we should make more
> generic? Something like "max size of the array we should consider when
> performing transforms"? At that point we could also use it inside
> `Instruction *InstCombiner::foldCmpLoadFromIndexedGlobal` which
> hardcodes a similar threshold. What do you think?

That sounds good.

-- Sanjoy

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