[PATCH] D59153: [MBP] Make sure the exit BB is the most possible successor before rotating a loop

[Guozhi Wei via Phabricator via llvm-commits]

Carrot created this revision.
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In findBestLoopExit it only finds a BB that can exit a loop, but it doesn't consider the exit BB may have other better predecessor. In that case the exit BB is placed after other predecessor, rotation actually makes loop layout worse.


Repository:
  rL LLVM

https://reviews.llvm.org/D59153

Files:
  lib/CodeGen/MachineBlockPlacement.cpp
  test/CodeGen/X86/bb_rotate.ll

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