[PATCH] Add HLE target feature

[Jeffrey Yasskin]

On Wed, Feb 20, 2013 at 5:42 PM, Nadav Rotem <nrotem at apple.com> wrote:
> Michael,
>
> Thanks for the explanation. I think that the question that we need to ask
> ourselves is, does this belong in the compiler ?  Before we design beautiful
> abstraction that will add to the complexity of the compiler we need to know
> if the complexity is worth it.  Michael, are you committed to doing
> __optimization__ work to support transactional memory ? If so, how will this
> work benefit others ?  To my understanding, transactional memory is not
> something that is going to benefit many people.

These instructions will benefit many people. They have the potential
to speed up both atomic implementations and any user code that uses
mutexes whose implementation takes advantage of them. Don't judge
these instructions by previous attempts at transactional memory.

That I see large benefits from them doesn't necessarily mean I think
they need to be metadata on the atomic instructions as opposed to
x86-specific intrinsics. I think we need to see the specification in
the IR before coming to any conclusions about that.

Jeffrey