[all-commits] [llvm/llvm-project] c35585: DomTree: Make PostDomTree immune to block successo...

[Yevgeny Rouban via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: c35585e209efe69e2233bdc5ecd23bed7b735ba3
      https://github.com/llvm/llvm-project/commit/c35585e209efe69e2233bdc5ecd23bed7b735ba3
  Author: Yevgeny Rouban <yrouban at azul.com>
  Date:   2020-08-05 (Wed, 05 Aug 2020)

  Changed paths:
    M llvm/include/llvm/Support/GenericDomTreeConstruction.h
    A llvm/test/Transforms/InstCombine/infinite-loop-postdom.ll

  Log Message:
  -----------
  DomTree: Make PostDomTree immune to block successors swap

This is another fix for the bug 46098 where PostDominatorTree
is unexpectedly changed by InstCombine's branch swapping
transformation.
This patch fixes PostDomTree builder. While looking for
the furthest away node in a reverse unreachable subgraph
this patch runs DFS with successors in their function order.
This order is indifferent to the order of successors, so is
the furthest away node.

Reviewers: kuhar, nikic, lebedev.ri
Differential Revision: https://reviews.llvm.org/D84763