tree e46a3467aaf7ad41472438905a29c565a7c72de4
parent db54e001d51f5ba6cf6cdb048e91f0d277c10a73
author Wei Mi <wmi@google.com> 1613187988 -0800
committer Copybara-Service <copybara-worker@google.com> 1613735168 -0800

[SampleFDO] Stop repeated indirect call promotion for the same target.

Found a problem in indirect call promotion in sample loader pass. Currently
if an indirect call is promoted for a target, and if the parent function is
inlined into some other function, the indirect call can be promoted for the
same target again. That is redundent which can harm performance and can cause
excessive compile time in some extreme case.

The patch fixes the issue. If a target is promoted for an indirect call, the
patch will write ICP metadata with the target call count being set to 0.
In the later ICP in sample profile loader, if it sees a target has 0 count
for an indirect call, it knows the target has been promoted and won't do
indirect call promotion for the indirect call.

The fix brings 0.1~0.2% performance on our search benchmark.

Differential Revision: https://reviews.llvm.org/D96806

GitOrigin-RevId: 5fb65c02ca5e91e7e1a00e0efdb8edc899f3e4b9