[llvm] r348781 - [DAGCombiner] Remove unnecessary recursive DAGCombiner::visitINSERT_SUBVECTOR call.

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Mon Dec 10 10:18:50 2018
New Revision: 348781

URL: http://llvm.org/viewvc/llvm-project?rev=348781&view=rev
Log:
[DAGCombiner] Remove unnecessary recursive DAGCombiner::visitINSERT_SUBVECTOR call.

As discussed on D55511, this caused an issue if the inner node deletes a node that the outer node depends upon. As it doesn't affect any lit-tests and I've only been able to expose this with the D55511 change I'm committing this now.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=348781&r1=348780&r2=348781&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Mon Dec 10 10:18:50 2018
@@ -17717,12 +17717,6 @@ SDValue DAGCombiner::visitINSERT_SUBVECT
   if (N1.isUndef())
     return N0;
 
-  // For nested INSERT_SUBVECTORs, attempt to combine inner node first to allow
-  // us to pull BITCASTs from input to output.
-  if (N0.hasOneUse() && N0->getOpcode() == ISD::INSERT_SUBVECTOR)
-    if (SDValue NN0 = visitINSERT_SUBVECTOR(N0.getNode()))
-      return DAG.getNode(ISD::INSERT_SUBVECTOR, SDLoc(N), VT, NN0, N1, N2);
-
   // If this is an insert of an extracted vector into an undef vector, we can
   // just use the input to the extract.
   if (N0.isUndef() && N1.getOpcode() == ISD::EXTRACT_SUBVECTOR &&