[LLVMdev] [RFC] Add Intel TSX HLE Support

Nadav Rotem nrotem at apple.com
Thu Feb 28 17:10:25 PST 2013


On Feb 28, 2013, at 11:19 AM, Michael Ilseman <milseman at apple.com> wrote:

> Nadav, I've been reading over the patches and I was wondering if you could elaborate your concerns here. I share your goal of reducing compilation time regressions for users that don't care about new feature X. From my very quick glance over the patches, I didn't see anything I couldn't opt out of. Maybe we can talk about specifics and figure out a way to make these changes not affect other users/targets.
> 
> Let's say I care about a non-X86, non-TM target and compilation time. What's the negative impact to me from these patches? Is there a cost I can't opt out of?
> 
> Let's say I care about X86 non-TM compilation time, what additional costs am I burdened with?

Hi Michael (Ilseman), 

As a non-x86 user you are going to have a slight negative impact on compile time and compiler code size. Its not a big deal. You need to pass additional parameters to all of the visitAtomicXXX && LegalizeXX methods. The initialization of Atomic operations will be slower because of the extra checks. Also, out of tree targets need to be updated. I don't think that this is a big deal, it is just another small increase in the compiler size and compile time. 

Thanks,
Nadav
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