Sink InstructionSelect() out of each target into SDISel, and rename it

DoInstructionSelection.  Inline "SelectRoot" into it from DAGISelHeader.
Sink some other stuff out of DAGISelHeader into SDISel.

Eliminate the various 'Indent' stuff from various targets, which dates
to when isel was recursive.

 17 files changed, 114 insertions(+), 430 deletions(-)



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97555 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 59 insertions, 2 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index c0b0d7254f..b13ef3a02a 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -723,9 +723,9 @@ void SelectionDAGISel::CodeGenAndEmitDAG() {
   // code to the MachineBasicBlock.
   if (TimePassesIsEnabled) {
     NamedRegionTimer T("Instruction Selection", GroupName);
-    InstructionSelect();
+    DoInstructionSelection();
   } else {
-    InstructionSelect();
+    DoInstructionSelection();
   }
 
   DEBUG(dbgs() << "Selected selection DAG:\n");
@@ -765,6 +765,63 @@ void SelectionDAGISel::CodeGenAndEmitDAG() {
   DEBUG(BB->dump());
 }
 
+void SelectionDAGISel::DoInstructionSelection() {
+  DEBUG(errs() << "===== Instruction selection begins:\n");
+
+  PreprocessISelDAG();
+  
+  // Select target instructions for the DAG.
+  {
+    // Number all nodes with a topological order and set DAGSize.
+    DAGSize = CurDAG->AssignTopologicalOrder();
+    
+    // Create a dummy node (which is not added to allnodes), that adds
+    // a reference to the root node, preventing it from being deleted,
+    // and tracking any changes of the root.
+    HandleSDNode Dummy(CurDAG->getRoot());
+    ISelPosition = SelectionDAG::allnodes_iterator(CurDAG->getRoot().getNode());
+    ++ISelPosition;
+    
+    // The AllNodes list is now topological-sorted. Visit the
+    // nodes by starting at the end of the list (the root of the
+    // graph) and preceding back toward the beginning (the entry
+    // node).
+    while (ISelPosition != CurDAG->allnodes_begin()) {
+      SDNode *Node = --ISelPosition;
+      // Skip dead nodes. DAGCombiner is expected to eliminate all dead nodes,
+      // but there are currently some corner cases that it misses. Also, this
+      // makes it theoretically possible to disable the DAGCombiner.
+      if (Node->use_empty())
+        continue;
+      
+      SDNode *ResNode = Select(Node);
+      
+      // If node should not be replaced, continue with the next one.
+      if (ResNode == Node)
+        continue;
+      // Replace node.
+      if (ResNode)
+        ReplaceUses(Node, ResNode);
+      
+      // If after the replacement this node is not used any more,
+      // remove this dead node.
+      if (Node->use_empty()) { // Don't delete EntryToken, etc.
+        ISelUpdater ISU(ISelPosition);
+        CurDAG->RemoveDeadNode(Node, &ISU);
+      }
+    }
+    
+    CurDAG->setRoot(Dummy.getValue());
+  }    
+  DEBUG(errs() << "===== Instruction selection ends:\n");
+
+  PostprocessISelDAG();
+  
+  // FIXME: This shouldn't be needed, remove it.
+  CurDAG->RemoveDeadNodes();
+}
+
+
 void SelectionDAGISel::SelectAllBasicBlocks(Function &Fn,
                                             MachineFunction &MF,
                                             MachineModuleInfo *MMI,