1 //==-llvm/CodeGen/DAGISelHeader.h - Common DAG ISel definitions -*- C++ -*-==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file provides definitions of the common, target-independent methods and
11 // data, which is used by SelectionDAG-based instruction selectors.
13 // *** NOTE: This file is #included into the middle of the target
14 // instruction selector class. These functions are really methods.
15 // This is a little awkward, but it allows this code to be shared
16 // by all the targets while still being able to call into
17 // target-specific code without using a virtual function call.
19 //===----------------------------------------------------------------------===//
21 #ifndef LLVM_CODEGEN_DAGISEL_HEADER_H
22 #define LLVM_CODEGEN_DAGISEL_HEADER_H
24 /// ISelPosition - Node iterator marking the current position of
25 /// instruction selection as it procedes through the topologically-sorted
27 SelectionDAG::allnodes_iterator ISelPosition;
29 /// IsChainCompatible - Returns true if Chain is Op or Chain does
31 static bool IsChainCompatible(SDNode *Chain, SDNode *Op) {
32 if (Chain->getOpcode() == ISD::EntryToken)
34 else if (Chain->getOpcode() == ISD::TokenFactor)
36 else if (Chain->getNumOperands() > 0) {
37 SDValue C0 = Chain->getOperand(0);
38 if (C0.getValueType() == MVT::Other)
39 return C0.getNode() != Op && IsChainCompatible(C0.getNode(), Op);
44 /// ISelUpdater - helper class to handle updates of the
45 /// instruciton selection graph.
46 class VISIBILITY_HIDDEN ISelUpdater : public SelectionDAG::DAGUpdateListener {
47 SelectionDAG::allnodes_iterator &ISelPosition;
48 bool HadDelete; // Indicate if any deletions were done.
50 explicit ISelUpdater(SelectionDAG::allnodes_iterator &isp)
51 : ISelPosition(isp) {}
53 /// NodeDeleted - remove node from the selection queue.
54 virtual void NodeDeleted(SDNode *N, SDNode *E) {
55 if (ISelPosition == SelectionDAG::allnodes_iterator(N))
59 /// NodeUpdated - Ignore updates for now.
60 virtual void NodeUpdated(SDNode *N) {}
63 /// ReplaceUses - replace all uses of the old node F with the use
64 /// of the new node T.
65 void ReplaceUses(SDValue F, SDValue T) DISABLE_INLINE {
66 ISelUpdater ISU(ISelPosition);
67 CurDAG->ReplaceAllUsesOfValueWith(F, T, &ISU);
70 /// ReplaceUses - replace all uses of the old nodes F with the use
71 /// of the new nodes T.
72 void ReplaceUses(const SDValue *F, const SDValue *T,
73 unsigned Num) DISABLE_INLINE {
74 ISelUpdater ISU(ISelPosition);
75 CurDAG->ReplaceAllUsesOfValuesWith(F, T, Num, &ISU);
78 /// ReplaceUses - replace all uses of the old node F with the use
79 /// of the new node T.
80 void ReplaceUses(SDNode *F, SDNode *T) DISABLE_INLINE {
81 unsigned FNumVals = F->getNumValues();
82 unsigned TNumVals = T->getNumValues();
83 ISelUpdater ISU(ISelPosition);
84 if (FNumVals != TNumVals) {
85 for (unsigned i = 0, e = std::min(FNumVals, TNumVals); i < e; ++i)
86 CurDAG->ReplaceAllUsesOfValueWith(SDValue(F, i), SDValue(T, i), &ISU);
88 CurDAG->ReplaceAllUsesWith(F, T, &ISU);
92 /// SelectRoot - Top level entry to DAG instruction selector.
93 /// Selects instructions starting at the root of the current DAG.
94 void SelectRoot(SelectionDAG &DAG) {
97 // Create a dummy node (which is not added to allnodes), that adds
98 // a reference to the root node, preventing it from being deleted,
99 // and tracking any changes of the root.
100 HandleSDNode Dummy(CurDAG->getRoot());
101 ISelPosition = next(SelectionDAG::allnodes_iterator(CurDAG->getRoot().getNode()));
103 // Select pending nodes from the instruction selection queue
104 // until no more nodes are left for selection.
105 while (ISelPosition != CurDAG->allnodes_begin()) {
106 SDNode *Node = --ISelPosition;
108 DAG.setSubgraphColor(Node, "red");
110 SDNode *ResNode = Select(SDValue(Node, 0));
111 // If node should not be replaced,
112 // continue with the next one.
118 DAG.setSubgraphColor(ResNode, "yellow");
119 DAG.setSubgraphColor(ResNode, "black");
121 ReplaceUses(Node, ResNode);
123 // If after the replacement this node is not used any more,
124 // remove this dead node.
125 if (Node->use_empty()) { // Don't delete EntryToken, etc.
126 ISelUpdater ISU(ISelPosition);
127 CurDAG->RemoveDeadNode(Node, &ISU);
131 CurDAG->setRoot(Dummy.getValue());
134 #endif /* LLVM_CODEGEN_DAGISEL_HEADER_H */