[all-commits] [llvm/llvm-project] 029e83: [DAG] getNode - don't bother creating ADDO(X, 0) or...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 029e83b401564db2562f0dc68c55563806570872
      https://github.com/llvm/llvm-project/commit/029e83b401564db2562f0dc68c55563806570872
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2022-07-20 (Wed, 20 Jul 2022)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

  Log Message:
  -----------
  [DAG] getNode - don't bother creating ADDO(X,0) or SUBO(X,0) nodes.

Similar to what we already do in getNode for basic ADD/SUB nodes, return the X operand directly, but here we know that there will be no/zero overflow as well.

As noted on D127115 - this path is being exercised by llvm/test/CodeGen/ARM/dsp-mlal.ll, although I haven't been able to get any codegen without a topological worklist.