[all-commits] [llvm/llvm-project] 0ea775: [LoopFlatten] Updating Phi nodes after IV widening

[sjoerdmeijer via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0ea77502e22115dca6bcf82f895072ec67f3d565
      https://github.com/llvm/llvm-project/commit/0ea77502e22115dca6bcf82f895072ec67f3d565
  Author: Sjoerd Meijer <sjoerd.meijer at arm.com>
  Date:   2021-09-28 (Tue, 28 Sep 2021)

  Changed paths:
    M llvm/lib/Transforms/Scalar/LoopFlatten.cpp
    M llvm/test/Transforms/LoopFlatten/widen-iv2.ll

  Log Message:
  -----------
  [LoopFlatten] Updating Phi nodes after IV widening

In rG6a076fa9539e, a problem with updating the old/narrow phi nodes after IV
widening was introduced. If after widening of the IV the transformation is
*not* applied, the narrow phi node was incorrectly modified, which should only
happen if flattening happens. This can be seen in the added test widen-iv2.ll,
which incorrectly had 1 incoming value, but should have its original 2 incoming
values, which is now restored.

Differential Revision: https://reviews.llvm.org/D110234