[PATCH] D145171: [FSAFDO] Improve FS discriminator encoding

Thu Mar 9 10:21:29 PST 2023

hoy added a comment.

In D145171#4182014 <https://reviews.llvm.org/D145171#4182014>, @xur wrote:

> The total improvement really depends on programs. On average, I would say 1.5% to 2.0%.  For some programs, like clang itself, FSAFDO improve ~3% over AFDO.
> There is also a small change on the create_llvm_prof tool side. We will update the tool soon.

The numbers are exciting! I'll let you know our numbers once ready.

BTW, I'll started the integration with CSSPGO base off here. Pseudo probes have a potential to allow more bits for the FS discriminator and additional FS passes. Implementation-wise, the potential comes from placing the FS discriminator field as a separate int64 operand of the pseudo probe intrinsic, instead of using the existing dbg metadata. I would like your thoughts about whether it's worth the diversion. Thanks.

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  https://reviews.llvm.org/D145171/new/

https://reviews.llvm.org/D145171