tree 77852fb8b6efdc5aa31699acfdf4839364e3e5ea
parent c562e3f4ca332ad75dfac41900953fc23b6f7353
author Sanjay Patel <spatel@rotateright.com> 1618253511 -0400
committer Copybara-Service <copybara-worker@google.com> 1618357947 -0700

[PassManager][PhaseOrdering] lower expects before running simplifyCFG

Retry of 330619a3a623 that includes a clang test update.

Original commit message:

If we run passes before lowering llvm.expect intrinsics to metadata,
then those passes have no way to act on the hints provided by llvm.expect.
SimplifyCFG is the known offender, and we made it smarter about profile
metadata in D98898 <https://reviews.llvm.org/D98898>.

In the motivating example from https://llvm.org/PR49336 , this means we
were ignoring the recommended method for a programmer to tell the compiler
that a compare+branch is expensive. This change appears to solve that case -
the metadata survives to the backend, the compare order is as expected in IR,
and the backend does not do anything to reverse it.

We make the same change to the old pass manager to keep things synchronized.

Differential Revision: https://reviews.llvm.org/D100213

GitOrigin-RevId: 661cc71a1c50081389d73b2baae02f51df670ba1