[PATCH] D107876: [CSSPGO] Allow the use of debug-info-for-profiling and pseudo-probe-for-profiling together

[Hongtao Yu via Phabricator via llvm-commits]

hoy added a comment.

In D107876#2939624 <https://reviews.llvm.org/D107876#2939624>, @wmi wrote:

> Could you remind me the discriminator difference between debug info based AFDO and pseudo probe based AFDO? I forgot it. I am sure it is described in some patch but I havn't found it. Give me a pointer is good enough.

In short, unlike block pseudo probe, a callsite probe relies on the calliste discriminator to be tracked. This has a couple usage: 1. to track direct call and indirect callsite 2. to model inline contexts with a list of callsite probes.

A probe discriminator is treated as empty or null for AutoFDO since it has lowest three bits as "111".


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