[llvm-dev] [RFC] IR-level Region Annotations
Hal Finkel via llvm-dev
llvm-dev at lists.llvm.org
Tue Jan 17 16:36:37 PST 2017
On 01/17/2017 05:36 PM, Wael Yehia via llvm-dev wrote:
> Hi. Regarding the token approach, I've read some documentation
> (review D11861, EH in llvm, and Reid and David's presentation) but
> couldn't answer the following question.
> Does the intrinsic or the instruction returning a /token/ type object
> act as a code motion barrier? In other words, does it prevent other
> operations from being reordered with it?
> If the answer is no, then does it mean the intrinsic has to be marked
> with the /convergent/ property to achieve the code motion barrier effect?
To clarify, convergent does not form a code-motion barrier. It prevents
transformations from adding additional control dependencies. I suspect
that the token type does the same (because tokens can't appear in PHIs).
Actual code motion barriers are generally achieved by adding unknown
> If yes, can someone explain how is that achieved in llvm?
> Greatly appreciated. Thanks.
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the llvm-dev