[all-commits] [llvm/llvm-project] 64f1bb: [gicombiner] Add GIMatchTree and use it for the co...

[Daniel Sanders via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 64f1bb5cd2c6d69af7c74ec68840029603560238
      https://github.com/llvm/llvm-project/commit/64f1bb5cd2c6d69af7c74ec68840029603560238
  Author: Daniel Sanders <daniel_l_sanders at apple.com>
  Date:   2020-01-03 (Fri, 03 Jan 2020)

  Changed paths:
    M llvm/include/llvm/Target/GlobalISel/Combine.td
    A llvm/test/TableGen/GICombinerEmitter/match-tree.td
    M llvm/utils/TableGen/GICombinerEmitter.cpp
    M llvm/utils/TableGen/GlobalISel/CMakeLists.txt
    M llvm/utils/TableGen/GlobalISel/GIMatchDag.h
    M llvm/utils/TableGen/GlobalISel/GIMatchDagEdge.cpp
    M llvm/utils/TableGen/GlobalISel/GIMatchDagEdge.h
    M llvm/utils/TableGen/GlobalISel/GIMatchDagInstr.h
    M llvm/utils/TableGen/GlobalISel/GIMatchDagPredicate.cpp
    M llvm/utils/TableGen/GlobalISel/GIMatchDagPredicate.h
    M llvm/utils/TableGen/GlobalISel/GIMatchDagPredicateDependencyEdge.cpp
    A llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp
    A llvm/utils/TableGen/GlobalISel/GIMatchTree.h

  Log Message:
  -----------
  [gicombiner] Add GIMatchTree and use it for the code generation

Summary:
GIMatchTree's job is to build a decision tree by zipping all the
GIMatchDag's together.

Each DAG is added to the tree builder as a leaf and partitioners are used
to subdivide each node until there are no more partitioners to apply. At
this point, the code generator is responsible for testing any untested
predicates and following any unvisited traversals (there shouldn't be any
of the latter as the getVRegDef partitioner handles them all).

Note that the leaves don't always fit into partitions cleanly and the
partitions may overlap as a result. This is resolved by cloning the leaf
into every partition it belongs to. One example of this is a rule that can
match one of N opcodes. The leaf for this rule would end up in N partitions
when processed by the opcode partitioner. A similar example is the
getVRegDef partitioner where having rules (add $a, $b), and (add ($a, $b), $c)
will result in the former being in the partition for successfully
following the vreg-def and failing to do so as it doesn't care which
happens.

Depends on D69151

Reviewers: bogner, volkan

Reviewed By: volkan

Subscribers: lkail, mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69152