Eliminate the ISel priority queue, which used the topological order for a

priority function. Instead, just iterate over the AllNodes list, which is
already in topological order. This eliminates a fair amount of bookkeeping,
and speeds up the isel phase by about 15% on many testcases.

The impact on most targets is that AddToISelQueue calls can be simply removed.

In the x86 target, there are two additional notable changes.

The rule-bending AND+SHIFT optimization in MatchAddress that creates new
pre-isel nodes during isel is now a little more verbose, but more robust.
Instead of either creating an invalid DAG or creating an invalid topological
sort, as it has historically done, it can now just insert the new nodes into
the node list at a position where they will be consistent with the topological
ordering.

Also, the address-matching code has logic that checked to see if a node was
"already selected". However, when a node is selected, it has all its uses
taken away via ReplaceAllUsesWith or equivalent, so it won't recieve any
further visits from MatchAddress. This code is now removed.

llvm-svn: 58748

1 files changed, 0 insertions, 14 deletions

diff --git a/llvm/lib/Target/Alpha/AlphaISelDAGToDAG.cpp b/llvm/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
index e0ae5564ed8..801db44faf7 100644
--- a/llvm/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
+++ b/llvm/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
@@ -174,7 +174,6 @@ namespace {
       default: return true;
       case 'm':   // memory
         Op0 = Op;
-        AddToISelQueue(Op0);
         break;
       }
       
@@ -270,9 +269,6 @@ SDNode *AlphaDAGToDAGISel::Select(SDValue Op) {
     SDValue N0 = Op.getOperand(0);
     SDValue N1 = Op.getOperand(1);
     SDValue N2 = Op.getOperand(2);
-    AddToISelQueue(N0);
-    AddToISelQueue(N1);
-    AddToISelQueue(N2);
     Chain = CurDAG->getCopyToReg(Chain, Alpha::R24, N1, 
                                  SDValue(0,0));
     Chain = CurDAG->getCopyToReg(Chain, Alpha::R25, N2, 
@@ -289,7 +285,6 @@ SDNode *AlphaDAGToDAGISel::Select(SDValue Op) {
 
   case ISD::READCYCLECOUNTER: {
     SDValue Chain = N->getOperand(0);
-    AddToISelQueue(Chain); //Select chain
     return CurDAG->getTargetNode(Alpha::RPCC, MVT::i64, MVT::Other,
                                  Chain);
   }
@@ -368,8 +363,6 @@ SDNode *AlphaDAGToDAGISel::Select(SDValue Op) {
       };
       SDValue tmp1 = N->getOperand(rev?1:0);
       SDValue tmp2 = N->getOperand(rev?0:1);
-      AddToISelQueue(tmp1);
-      AddToISelQueue(tmp2);
       SDNode *cmp = CurDAG->getTargetNode(Opc, MVT::f64, tmp1, tmp2);
       if (inv) 
         cmp = CurDAG->getTargetNode(Alpha::CMPTEQ, MVT::f64, SDValue(cmp, 0), 
@@ -406,9 +399,6 @@ SDNode *AlphaDAGToDAGISel::Select(SDValue Op) {
       SDValue cond = N->getOperand(0);
       SDValue TV = N->getOperand(1);
       SDValue FV = N->getOperand(2);
-      AddToISelQueue(cond);
-      AddToISelQueue(TV);
-      AddToISelQueue(FV);
       
       SDNode* LD = CurDAG->getTargetNode(Alpha::ITOFT, MVT::f64, cond);
       return CurDAG->getTargetNode(isDouble?Alpha::FCMOVNET:Alpha::FCMOVNES,
@@ -436,7 +426,6 @@ SDNode *AlphaDAGToDAGISel::Select(SDValue Op) {
         mask = mask | dontcare;
       
       if (get_zapImm(mask)) {
-        AddToISelQueue(N->getOperand(0).getOperand(0));
         SDValue Z = 
           SDValue(CurDAG->getTargetNode(Alpha::ZAPNOTi, MVT::i64,
                                           N->getOperand(0).getOperand(0),
@@ -460,7 +449,6 @@ void AlphaDAGToDAGISel::SelectCALL(SDValue Op) {
   SDValue Chain = N->getOperand(0);
   SDValue Addr = N->getOperand(1);
   SDValue InFlag(0,0);  // Null incoming flag value.
-  AddToISelQueue(Chain);
 
    std::vector<SDValue> CallOperands;
    std::vector<MVT> TypeOperands;
@@ -468,7 +456,6 @@ void AlphaDAGToDAGISel::SelectCALL(SDValue Op) {
    //grab the arguments
    for(int i = 2, e = N->getNumOperands(); i < e; ++i) {
      TypeOperands.push_back(N->getOperand(i).getValueType());
-     AddToISelQueue(N->getOperand(i));
      CallOperands.push_back(N->getOperand(i));
    }
    int count = N->getNumOperands() - 2;
@@ -514,7 +501,6 @@ void AlphaDAGToDAGISel::SelectCALL(SDValue Op) {
      Chain = SDValue(CurDAG->getTargetNode(Alpha::BSR, MVT::Other, MVT::Flag, 
                                              Addr.getOperand(0), Chain, InFlag), 0);
    } else {
-     AddToISelQueue(Addr);
      Chain = CurDAG->getCopyToReg(Chain, Alpha::R27, Addr, InFlag);
      InFlag = Chain.getValue(1);
      Chain = SDValue(CurDAG->getTargetNode(Alpha::JSR, MVT::Other, MVT::Flag,