[llvm-dev] Deprecating ADDC/ADDE/SUBC/SUBE

whitequark via llvm-dev llvm-dev at lists.llvm.org
Thu May 31 11:28:22 PDT 2018


On 2018-05-30 16:57, Amaury Séchet via llvm-dev wrote:
> These opcodes have been deprecated about a year ago, but still in use
> in various backend.
> 
> In https://reviews.llvm.org/D47422 I would like to change the behavior
> of the backend to not enable the use of these opcodes by default. The
> opcode remains usable by any backend that wish to use them, but that
> should limit the situation where newer backend just use them as they
> are enabled by default.
> 
> This shouldn't break any out of tree backend, however, it may cause
> misoptimisation if the backend dev do not activate these opcodes via
> setOperationAction and rely on them for some of their optimizations.

Thanks for heads up, this will impact the OR1K backend.

Is there any guidance for migrating to U*O/*CARRY?

-- 
whitequark


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