[all-commits] [llvm/llvm-project] 520e3d: [gicombiner] Process the MatchDag such that every ...

[Daniel Sanders via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 520e3d66e7257c77f1226185504bbe1cb90afcfa
      https://github.com/llvm/llvm-project/commit/520e3d66e7257c77f1226185504bbe1cb90afcfa
  Author: Daniel Sanders <daniel_l_sanders at apple.com>
  Date:   2019-12-17 (Tue, 17 Dec 2019)

  Changed paths:
    M llvm/include/llvm/ADT/iterator.h
    M llvm/test/TableGen/GICombinerEmitter/parse-match-pattern.td
    M llvm/utils/TableGen/GICombinerEmitter.cpp
    M llvm/utils/TableGen/GlobalISel/GIMatchDag.h
    M llvm/utils/TableGen/GlobalISel/GIMatchDagEdge.cpp
    M llvm/utils/TableGen/GlobalISel/GIMatchDagEdge.h

  Log Message:
  -----------
  [gicombiner] Process the MatchDag such that every node is reachable from the roots

Summary:
When we build the walk across these DAG's we need to be able to reach every node
from the roots. Flip and traversal edges (so that use->def becomes def->uses)
that make nodes unreachable. Note that early on we'll just error out on these
flipped edges as def->uses edges are more complicated to match due to their
one->many nature.

Depends on D69077

Reviewers: volkan, bogner

Subscribers: llvm-commits