[all-commits] [llvm/llvm-project] 815543: [Attributor] Allow PHI nodes in AAValueConstantRan...

[Johannes Doerfert via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 8155439331ac8f85be54adbd053c100567927d7c
      https://github.com/llvm/llvm-project/commit/8155439331ac8f85be54adbd053c100567927d7c
  Author: Johannes Doerfert <johannes at jdoerfert.de>
  Date:   2020-02-10 (Mon, 10 Feb 2020)

  Changed paths:
    M llvm/lib/Transforms/IPO/Attributor.cpp
    M llvm/test/Transforms/Attributor/liveness.ll
    M llvm/test/Transforms/Attributor/range.ll
    M llvm/test/Transforms/Attributor/willreturn.ll

  Log Message:
  -----------
  [Attributor] Allow PHI nodes in AAValueConstantRangeFloating

Traversing PHI nodes is natural with the genericValueTraversal but also
a bit tricky. The problem is similar to the ones we have seen in AAAlign
and AADereferenceable, namely that we continue to increase the range in
each iteration. We use a pessimistic approach here to stop the
iterations. Nevertheless, optimistic information can now be propagated
through a PHI node.