[llvm-commits] [llvm] r47052 - /llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

[Chris Lattner]

Author: lattner
Date: Wed Feb 13 01:25:05 2008
New Revision: 47052

URL: http://llvm.org/viewvc/llvm-project?rev=47052&view=rev
Log:
teach dag combiner how to eliminate MERGE_VALUES nodes.

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=47052&r1=47051&r2=47052&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Feb 13 01:25:05 2008
@@ -137,6 +137,7 @@
     //   otherwise            - N should be replaced by the returned Operand.
     //
     SDOperand visitTokenFactor(SDNode *N);
+    SDOperand visitMERGE_VALUES(SDNode *N);
     SDOperand visitADD(SDNode *N);
     SDOperand visitSUB(SDNode *N);
     SDOperand visitADDC(SDNode *N);
@@ -662,6 +663,7 @@
   switch(N->getOpcode()) {
   default: break;
   case ISD::TokenFactor:        return visitTokenFactor(N);
+  case ISD::MERGE_VALUES:       return visitMERGE_VALUES(N);
   case ISD::ADD:                return visitADD(N);
   case ISD::SUB:                return visitSUB(N);
   case ISD::ADDC:               return visitADDC(N);
@@ -837,6 +839,18 @@
   return Result;
 }
 
+/// MERGE_VALUES can always be eliminated.
+SDOperand DAGCombiner::visitMERGE_VALUES(SDNode *N) {
+  WorkListRemover DeadNodes(*this);
+  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
+    DAG.ReplaceAllUsesOfValueWith(SDOperand(N, i), N->getOperand(i),
+                                  &DeadNodes);
+  removeFromWorkList(N);
+  DAG.DeleteNode(N);
+  return SDOperand(N, 0);   // Return N so it doesn't get rechecked!
+}
+
+
 static
 SDOperand combineShlAddConstant(SDOperand N0, SDOperand N1, SelectionDAG &DAG) {
   MVT::ValueType VT = N0.getValueType();