Displaying 5 results from an estimated 5 matches for "d85603".
2020 Aug 09
2
_mm_lfence in both pathes of an if/else are hoisted by SimplfyCFG potentially breaking use as a speculation barrier
Hi Craig,
The review for the similar GPU problem is now up here:
https://reviews.llvm.org/D85603 (+ some other patches on the
Phabricator stack).
>From a pragmatic perspective, the constraints added to program
transforms there are sufficient for what you need. You'd produce IR
such as:
%token = call token @llvm.experimental.convergence.anchor()
br i1 %c, label %then, label %el...
2020 Aug 09
2
[RFC] Introducing convergence control bundles and intrinsics
Hi all,
please see https://reviews.llvm.org/D85603 and its related changes for
our most recent and hopefully final attempt at putting the `convergent`
attribute on a solid theoretical foundation in a way that is useful for
modern GPU compiler use cases. We have clear line of sight to enabling a
new control flow implementation in the AMDGPU back...
2020 Aug 17
2
[RFC] Introducing convergence control bundles and intrinsics
...ergent` on most things, but
that effort got stuck. In the meantime, let's avoid adding yet another
odd duck like this :)
Cheers,
Nicolai
>
> -Hal
>
> On 8/9/20 10:03 AM, Nicolai Hähnle via llvm-dev wrote:
> > Hi all,
> >
> > please see https://reviews.llvm.org/D85603 and its related changes for
> > our most recent and hopefully final attempt at putting the
> > `convergent` attribute on a solid theoretical foundation in a way that
> > is useful for modern GPU compiler use cases. We have clear line of
> > sight to enabling a new control fl...
2020 Aug 17
2
[RFC] Introducing convergence control bundles and intrinsics
...s others are
affected as well.
Cheers,
Nicolai
>
> -Hal
>
>
> >
> >
> >> -Hal
> >>
> >> On 8/9/20 10:03 AM, Nicolai Hähnle via llvm-dev wrote:
> >>> Hi all,
> >>>
> >>> please see https://reviews.llvm.org/D85603 and its related changes for
> >>> our most recent and hopefully final attempt at putting the
> >>> `convergent` attribute on a solid theoretical foundation in a way that
> >>> is useful for modern GPU compiler use cases. We have clear line of
> >>> si...
2020 Jul 28
2
_mm_lfence in both pathes of an if/else are hoisted by SimplfyCFG potentially breaking use as a speculation barrier
_mm_lfence was originally documented as a load fence. But in light of
speculative execution vulnerabilities it has started being advertised as a
way to prevent speculative execution. Current Intel Software Development
Manual documents it as "Specifically, LFENCE does not execute until all
prior instructions have completed locally, and no later instruction begins
execution until LFENCE