1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
//==-llvm/CodeGen/DAGISelHeader.h - Common DAG ISel definitions -*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides definitions of the common, target-independent methods and
// data, which is used by SelectionDAG-based instruction selectors.
//
// *** NOTE: This file is #included into the middle of the target
// instruction selector class. These functions are really methods.
// This is a little awkward, but it allows this code to be shared
// by all the targets while still being able to call into
// target-specific code without using a virtual function call.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_DAGISEL_HEADER_H
#define LLVM_CODEGEN_DAGISEL_HEADER_H
/// ISelPosition - Node iterator marking the current position of
/// instruction selection as it procedes through the topologically-sorted
/// node list.
SelectionDAG::allnodes_iterator ISelPosition;
/// IsChainCompatible - Returns true if Chain is Op or Chain does
/// not reach Op.
static bool IsChainCompatible(SDNode *Chain, SDNode *Op) {
if (Chain->getOpcode() == ISD::EntryToken)
return true;
if (Chain->getOpcode() == ISD::TokenFactor)
return false;
if (Chain->getNumOperands() > 0) {
SDValue C0 = Chain->getOperand(0);
if (C0.getValueType() == MVT::Other)
return C0.getNode() != Op && IsChainCompatible(C0.getNode(), Op);
}
return true;
}
/// ISelUpdater - helper class to handle updates of the
/// instruciton selection graph.
class VISIBILITY_HIDDEN ISelUpdater : public SelectionDAG::DAGUpdateListener {
SelectionDAG::allnodes_iterator &ISelPosition;
public:
explicit ISelUpdater(SelectionDAG::allnodes_iterator &isp)
: ISelPosition(isp) {}
/// NodeDeleted - Handle nodes deleted from the graph. If the
/// node being deleted is the current ISelPosition node, update
/// ISelPosition.
///
virtual void NodeDeleted(SDNode *N, SDNode *E) {
if (ISelPosition == SelectionDAG::allnodes_iterator(N))
++ISelPosition;
}
/// NodeUpdated - Ignore updates for now.
virtual void NodeUpdated(SDNode *N) {}
};
/// ReplaceUses - replace all uses of the old node F with the use
/// of the new node T.
DISABLE_INLINE void ReplaceUses(SDValue F, SDValue T) {
ISelUpdater ISU(ISelPosition);
CurDAG->ReplaceAllUsesOfValueWith(F, T, &ISU);
}
/// ReplaceUses - replace all uses of the old nodes F with the use
/// of the new nodes T.
DISABLE_INLINE void ReplaceUses(const SDValue *F, const SDValue *T,
unsigned Num) {
ISelUpdater ISU(ISelPosition);
CurDAG->ReplaceAllUsesOfValuesWith(F, T, Num, &ISU);
}
/// ReplaceUses - replace all uses of the old node F with the use
/// of the new node T.
DISABLE_INLINE void ReplaceUses(SDNode *F, SDNode *T) {
ISelUpdater ISU(ISelPosition);
CurDAG->ReplaceAllUsesWith(F, T, &ISU);
}
/// SelectRoot - Top level entry to DAG instruction selector.
/// Selects instructions starting at the root of the current DAG.
void SelectRoot(SelectionDAG &DAG) {
SelectRootInit();
// 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 = next(SelectionDAG::allnodes_iterator(CurDAG->getRoot().getNode()));
// 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;
#if 0
DAG.setSubgraphColor(Node, "red");
#endif
SDNode *ResNode = Select(SDValue(Node, 0));
// If node should not be replaced,
// continue with the next one.
if (ResNode == Node)
continue;
// Replace node.
if (ResNode) {
#if 0
DAG.setSubgraphColor(ResNode, "yellow");
DAG.setSubgraphColor(ResNode, "black");
#endif
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());
}
#endif /* LLVM_CODEGEN_DAGISEL_HEADER_H */
|
