[all-commits] [llvm/llvm-project] 25af35: [NewPM][LVI] Abandon LVI after CVP

[Nikita Popov via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 25af353b0e74907d5d50c8616b885bd1f73a68b3
      https://github.com/llvm/llvm-project/commit/25af353b0e74907d5d50c8616b885bd1f73a68b3
  Author: Nikita Popov <nikita.ppv at gmail.com>
  Date:   2020-08-01 (Sat, 01 Aug 2020)

  Changed paths:
    M clang/test/CodeGen/thinlto-distributed-newpm.ll
    M llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
    M llvm/test/Other/new-pm-defaults.ll
    M llvm/test/Other/new-pm-thinlto-defaults.ll
    M llvm/test/Other/new-pm-thinlto-postlink-pgo-defaults.ll
    M llvm/test/Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
    M llvm/test/Other/new-pm-thinlto-prelink-pgo-defaults.ll
    M llvm/test/Other/new-pm-thinlto-prelink-samplepgo-defaults.ll

  Log Message:
  -----------
  [NewPM][LVI] Abandon LVI after CVP

As mentioned on D70376, LVI can currently cause performance issues
when running under NewPM. The problem is that, unlike the legacy
pass manager, NewPM will not immediately discard the LVI analysis
if the following pass does not need it. This is a problem, because
LVI has a high memory requirement, and mass invalidation of LVI
values is very inefficient. LVI should only be alive during passes
that actively interact with it.

This patch addresses the issue by explicitly abandoning LVI after CVP,
which gets us back to the LegacyPM behavior.

Differential Revision: https://reviews.llvm.org/D84959