[PATCH] D58258: [HotColdSplit] Schedule splitting late to fix perf regression

[Vedant Kumar via Phabricator via llvm-commits]

vsk created this revision.
vsk added reviewers: tejohnson, hiraditya, anemet.
Herald added subscribers: jdoerfert, dexonsmith, steven_wu, mehdi_amini.
Herald added a project: LLVM.

With or without PGO data applied, splitting early in the pipeline
(either before the inliner or shortly after it) regresses performance
across SPEC variants. The cause appears to be that splitting hides
context for subsequent optimizations.

Schedule splitting late again, in effect reversing r352080, which
scheduled the splitting pass early for code size benefits (documented in
https://reviews.llvm.org/D57082).

rdar://47622429


https://reviews.llvm.org/D58258

Files:
  llvm/lib/Passes/PassBuilder.cpp
  llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
  llvm/test/Other/X86/lto-hot-cold-split.ll
  llvm/test/Other/new-pm-pgo.ll
  llvm/test/Other/opt-hot-cold-split.ll
  llvm/test/Other/pass-pipelines.ll

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