Remove the code from the scheduler that commuted two-address

instructions to avoid copies, because TwoAddressInstructionPass
also does this optimization.  The scheduler's version didn't
account for live-out values, which resulted in spurious commutes
and missed opportunities.

Now, TwoAddressInstructionPass handles all the opportunities,
instead of just those that the scheduler missed. The result is
usually the same, though there are occasional trivial differences
resulting from the avoidance of spurious commutes.

llvm-svn: 61611

1 files changed, 0 insertions, 54 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index aededf44440..e72c22c4727 100644
--- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -186,60 +186,6 @@ void ScheduleDAGRRList::Schedule() {
     ListScheduleTopDown();
   
   AvailableQueue->releaseState();
-
-  CommuteNodesToReducePressure();
-}
-
-/// CommuteNodesToReducePressure - If a node is two-address and commutable, and
-/// it is not the last use of its first operand, add it to the CommuteSet if
-/// possible. It will be commuted when it is translated to a MI.
-void ScheduleDAGRRList::CommuteNodesToReducePressure() {
-  SmallPtrSet<SUnit*, 4> OperandSeen;
-  for (unsigned i = Sequence.size(); i != 0; ) {
-    --i;
-    SUnit *SU = Sequence[i];
-    if (!SU || !SU->getNode()) continue;
-    if (SU->isCommutable) {
-      unsigned Opc = SU->getNode()->getMachineOpcode();
-      const TargetInstrDesc &TID = TII->get(Opc);
-      unsigned NumRes = TID.getNumDefs();
-      unsigned NumOps = TID.getNumOperands() - NumRes;
-      for (unsigned j = 0; j != NumOps; ++j) {
-        if (TID.getOperandConstraint(j+NumRes, TOI::TIED_TO) == -1)
-          continue;
-
-        SDNode *OpN = SU->getNode()->getOperand(j).getNode();
-        SUnit *OpSU = isPassiveNode(OpN) ? NULL : &SUnits[OpN->getNodeId()];
-        if (OpSU && OperandSeen.count(OpSU) == 1) {
-          // Ok, so SU is not the last use of OpSU, but SU is two-address so
-          // it will clobber OpSU. Try to commute SU if no other source operands
-          // are live below.
-          bool DoCommute = true;
-          for (unsigned k = 0; k < NumOps; ++k) {
-            if (k != j) {
-              OpN = SU->getNode()->getOperand(k).getNode();
-              OpSU = isPassiveNode(OpN) ? NULL : &SUnits[OpN->getNodeId()];
-              if (OpSU && OperandSeen.count(OpSU) == 1) {
-                DoCommute = false;
-                break;
-              }
-            }
-          }
-          if (DoCommute)
-            CommuteSet.insert(SU->getNode());
-        }
-
-        // Only look at the first use&def node for now.
-        break;
-      }
-    }
-
-    for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
-         I != E; ++I) {
-      if (!I->isCtrl())
-        OperandSeen.insert(I->getSUnit()->OrigNode);
-    }
-  }
 }
 
 //===----------------------------------------------------------------------===//