Move the point at which FastISel taps into the SelectionDAGISel

process up to a higher level. This allows FastISel to leverage
more of SelectionDAGISel's infastructure, such as updating Machine
PHI nodes.

Also, implement transitioning from SDISel back to FastISel in
the middle of a block, so it's now possible to go back and
forth. This allows FastISel to hand individual CallInsts and other
complicated things off to SDISel to handle, while handling the rest
of the block itself.

To help support this, reorganize the SelectionDAG class so that it
is allocated once and reused throughout a function, instead of
being completely reallocated for each block.

llvm-svn: 55219

1 files changed, 35 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 3e3890142f5..9275a21f9fb 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -547,11 +547,8 @@ void SelectionDAG::DeleteNodeNotInCSEMaps(SDNode *N) {
   // Drop all of the operands and decrement used nodes use counts.
   for (SDNode::op_iterator I = N->op_begin(), E = N->op_end(); I != E; ++I)
     I->getVal()->removeUser(std::distance(N->op_begin(), I), N);
-  if (N->OperandsNeedDelete) {
+  if (N->OperandsNeedDelete)
     delete[] N->OperandList;
-  }
-  N->OperandList = 0;
-  N->NumOperands = 0;
   
   AllNodes.remove(N);
 }
@@ -563,6 +560,9 @@ void SelectionDAG::DeleteNodeNotInCSEMaps(SDNode *N) {
 void SelectionDAG::RemoveNodeFromCSEMaps(SDNode *N) {
   bool Erased = false;
   switch (N->getOpcode()) {
+  case ISD::EntryToken:
+    assert(0 && "EntryToken should not be in CSEMaps!");
+    return;
   case ISD::HANDLENODE: return;  // noop.
   case ISD::CONDCODE:
     assert(CondCodeNodes[cast<CondCodeSDNode>(N)->get()] &&
@@ -764,24 +764,44 @@ unsigned SelectionDAG::getMVTAlignment(MVT VT) const {
 }
 
 SelectionDAG::SelectionDAG(TargetLowering &tli, MachineFunction &mf,
-                           FunctionLoweringInfo &fli, MachineModuleInfo *mmi,
-                           NodeAllocatorType &nodeallocator)
-  : TLI(tli), MF(mf), FLI(fli), MMI(mmi), NodeAllocator(nodeallocator) {
-  EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
+                           FunctionLoweringInfo &fli, MachineModuleInfo *mmi)
+  : TLI(tli), MF(mf), FLI(fli), MMI(mmi),
+    EntryNode(ISD::EntryToken, getVTList(MVT::Other)), 
+    Root(getEntryNode()) {
+  AllNodes.push_back(&EntryNode);
 }
 
 SelectionDAG::~SelectionDAG() {
+  allnodes_clear();
+}
+
+void SelectionDAG::allnodes_clear() {
   while (!AllNodes.empty()) {
     SDNode *N = AllNodes.remove(AllNodes.begin());
     N->SetNextInBucket(0);
-    if (N->OperandsNeedDelete) {
+    if (N->OperandsNeedDelete)
       delete [] N->OperandList;
-    }
-    N->OperandList = 0;
-    N->NumOperands = 0;
   }
 }
 
+void SelectionDAG::reset() {
+  allnodes_clear();
+  OperandAllocator.Reset();
+  CSEMap.clear();
+
+  ExtendedValueTypeNodes.clear();
+  ExternalSymbols.clear();
+  TargetExternalSymbols.clear();
+  std::fill(CondCodeNodes.begin(), CondCodeNodes.end(),
+            static_cast<CondCodeSDNode*>(0));
+  std::fill(ValueTypeNodes.begin(), ValueTypeNodes.end(),
+            static_cast<SDNode*>(0));
+
+  EntryNode.Uses = 0;
+  AllNodes.push_back(&EntryNode);
+  Root = getEntryNode();
+}
+
 SDValue SelectionDAG::getZeroExtendInReg(SDValue Op, MVT VT) {
   if (Op.getValueType() == VT) return Op;
   APInt Imm = APInt::getLowBitsSet(Op.getValueSizeInBits(),
@@ -3988,9 +4008,9 @@ SDNode *SelectionDAG::MorphNodeTo(SDNode *N, unsigned Opc,
       delete[] N->OperandList;
     if (N->isMachineOpcode()) {
       // We're creating a final node that will live unmorphed for the
-      // remainder of this SelectionDAG's duration, so we can allocate the
-      // operands directly out of the pool with no recycling metadata.
-      N->OperandList = Allocator.Allocate<SDUse>(NumOps);
+      // remainder of the current SelectionDAG iteration, so we can allocate
+      // the operands directly out of a pool with no recycling metadata.
+      N->OperandList = OperandAllocator.Allocate<SDUse>(NumOps);
       N->OperandsNeedDelete = false;
     } else {
       N->OperandList = new SDUse[NumOps];