SelectionDAG.h revision c3aea74ae5e29973c739b15cad3b8e0c408c35ed
1//===-- llvm/CodeGen/SelectionDAG.h - InstSelection DAG ---------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file declares the SelectionDAG class, and transitively defines the
11// SDNode class and subclasses.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CODEGEN_SELECTIONDAG_H
16#define LLVM_CODEGEN_SELECTIONDAG_H
17
18#include "llvm/CodeGen/SelectionDAGNodes.h"
19#include <map>
20#include <string> // FIXME remove eventually, turning map into const char* map.
21
22namespace llvm {
23  class TargetLowering;
24  class TargetMachine;
25  class MachineFunction;
26
27/// SelectionDAG class - This is used to represent a portion of an LLVM function
28/// in a low-level Data Dependence DAG representation suitable for instruction
29/// selection.  This DAG is constructed as the first step of instruction
30/// selection in order to allow implementation of machine specific optimizations
31/// and code simplifications.
32///
33/// The representation used by the SelectionDAG is a target-independent
34/// representation, which has some similarities to the GCC RTL representation,
35/// but is significantly more simple, powerful, and is a graph form instead of a
36/// linear form.
37///
38class SelectionDAG {
39  TargetLowering &TLI;
40  MachineFunction &MF;
41
42  // Root - The root of the entire DAG.  EntryNode - The starting token.
43  SDOperand Root, EntryNode;
44
45  // AllNodes - All of the nodes in the DAG
46  std::vector<SDNode*> AllNodes;
47
48  // ValueNodes - track SrcValue nodes
49  std::map<std::pair<const Value*, int>, SDNode*> ValueNodes;
50
51public:
52  SelectionDAG(TargetLowering &tli, MachineFunction &mf) : TLI(tli), MF(mf) {
53    EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
54  }
55  ~SelectionDAG();
56
57  MachineFunction &getMachineFunction() const { return MF; }
58  const TargetMachine &getTarget() const;
59  TargetLowering &getTargetLoweringInfo() const { return TLI; }
60
61  /// viewGraph - Pop up a ghostview window with the DAG rendered using 'dot'.
62  ///
63  void viewGraph();
64
65
66  typedef std::vector<SDNode*>::const_iterator allnodes_iterator;
67  allnodes_iterator allnodes_begin() const { return AllNodes.begin(); }
68  allnodes_iterator allnodes_end() const { return AllNodes.end(); }
69
70  /// getRoot - Return the root tag of the SelectionDAG.
71  ///
72  const SDOperand &getRoot() const { return Root; }
73
74  /// getEntryNode - Return the token chain corresponding to the entry of the
75  /// function.
76  const SDOperand &getEntryNode() const { return EntryNode; }
77
78  /// setRoot - Set the current root tag of the SelectionDAG.
79  ///
80  const SDOperand &setRoot(SDOperand N) { return Root = N; }
81
82  /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
83  /// compatible with the target instruction selector, as indicated by the
84  /// TargetLowering object.
85  ///
86  /// Note that this is an involved process that may invalidate pointers into
87  /// the graph.
88  void Legalize();
89
90  /// RemoveDeadNodes - This method deletes all unreachable nodes in the
91  /// SelectionDAG, including nodes (like loads) that have uses of their token
92  /// chain but no other uses and no side effect.  If a node is passed in as an
93  /// argument, it is used as the seed for node deletion.
94  void RemoveDeadNodes(SDNode *N = 0);
95
96  SDOperand getConstant(uint64_t Val, MVT::ValueType VT);
97  SDOperand getTargetConstant(uint64_t Val, MVT::ValueType VT);
98  SDOperand getConstantFP(double Val, MVT::ValueType VT);
99  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
100  SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
101  SDOperand getFrameIndex(int FI, MVT::ValueType VT);
102  SDOperand getConstantPool(unsigned CPIdx, MVT::ValueType VT);
103  SDOperand getBasicBlock(MachineBasicBlock *MBB);
104  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
105  SDOperand getValueType(MVT::ValueType);
106  SDOperand getRegister(unsigned Reg, MVT::ValueType VT);
107
108  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
109    return getNode(ISD::CopyToReg, MVT::Other, Chain,
110                   getRegister(Reg, N.getValueType()), N);
111  }
112
113  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
114    std::vector<MVT::ValueType> ResultTys;
115    ResultTys.push_back(VT);
116    ResultTys.push_back(MVT::Other);
117    std::vector<SDOperand> Ops;
118    Ops.push_back(Chain);
119    Ops.push_back(getRegister(Reg, VT));
120    return getNode(ISD::CopyFromReg, ResultTys, Ops);
121  }
122
123  SDOperand getImplicitDef(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
124    return getNode(ISD::ImplicitDef, MVT::Other, Chain, getRegister(Reg, VT));
125  }
126
127  /// getCall - Note that this destroys the vector of RetVals passed in.
128  ///
129  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
130                  SDOperand Callee, bool isTailCall = false) {
131    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, Chain,
132                            Callee);
133    NN->setValueTypes(RetVals);
134    AllNodes.push_back(NN);
135    return NN;
136  }
137
138  /// getCall - This is identical to the one above, and should be used for calls
139  /// where arguments are passed in physical registers.  This destroys the
140  /// RetVals and ArgsInRegs vectors.
141  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
142                  SDOperand Callee, std::vector<SDOperand> &ArgsInRegs,
143                  bool isTailCall = false) {
144    ArgsInRegs.insert(ArgsInRegs.begin(), Callee);
145    ArgsInRegs.insert(ArgsInRegs.begin(), Chain);
146    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, ArgsInRegs);
147    NN->setValueTypes(RetVals);
148    AllNodes.push_back(NN);
149    return NN;
150  }
151
152  SDOperand getCondCode(ISD::CondCode Cond);
153
154  /// getZeroExtendInReg - Return the expression required to zero extend the Op
155  /// value assuming it was the smaller SrcTy value.
156  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
157
158  /// getNode - Gets or creates the specified node.
159  ///
160  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
161  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
162  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
163                    SDOperand N1, SDOperand N2);
164  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
165                    SDOperand N1, SDOperand N2, SDOperand N3);
166  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
167                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
168  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
169                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
170                    SDOperand N5);
171  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
172                    std::vector<SDOperand> &Children);
173  SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
174                    std::vector<SDOperand> &Ops);
175
176  /// getSetCC - Helper function to make it easier to build SetCC's if you just
177  /// have an ISD::CondCode instead of an SDOperand.
178  ///
179  SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
180                     ISD::CondCode Cond) {
181    return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
182  }
183
184  /// getSelectCC - Helper function to make it easier to build SelectCC's if you
185  /// just have an ISD::CondCode instead of an SDOperand.
186  ///
187  SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
188                        SDOperand True, SDOperand False, ISD::CondCode Cond) {
189    MVT::ValueType VT = True.getValueType();
190    return getNode(ISD::SELECT_CC, VT, LHS, RHS, True, False,getCondCode(Cond));
191  }
192
193  /// getBR2Way_CC - Helper function to make it easier to build BRTWOWAY_CC
194  /// nodes.
195  ///
196  SDOperand getBR2Way_CC(SDOperand Chain, SDOperand CCNode, SDOperand LHS,
197                         SDOperand RHS, SDOperand True, SDOperand False) {
198    std::vector<SDOperand> Ops;
199    Ops.push_back(Chain);
200    Ops.push_back(CCNode);
201    Ops.push_back(LHS);
202    Ops.push_back(RHS);
203    Ops.push_back(True);
204    Ops.push_back(False);
205    return getNode(ISD::BRTWOWAY_CC, MVT::Other, Ops);
206  }
207
208  /// getLoad - Loads are not normal binary operators: their result type is not
209  /// determined by their operands, and they produce a value AND a token chain.
210  ///
211  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
212                    SDOperand SV);
213  SDOperand getExtLoad(unsigned Opcode, MVT::ValueType VT, SDOperand Chain,
214                       SDOperand Ptr, SDOperand SV, MVT::ValueType EVT);
215
216  // getSrcValue - construct a node to track a Value* through the backend
217  SDOperand getSrcValue(const Value* I, int offset = 0);
218
219
220  /// SelectNodeTo - These are used for target selectors to *mutate* the
221  /// specified node to have the specified return type, Target opcode, and
222  /// operands.  Note that target opcodes are stored as
223  /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field.
224  void SelectNodeTo(SDNode *N, MVT::ValueType VT, unsigned TargetOpc,
225                    SDOperand Op1);
226  void SelectNodeTo(SDNode *N, MVT::ValueType VT, unsigned TargetOpc,
227                    SDOperand Op1, SDOperand Op2);
228  void SelectNodeTo(SDNode *N, MVT::ValueType VT, unsigned TargetOpc,
229                    SDOperand Op1, SDOperand Op2, SDOperand Op3);
230  void SelectNodeTo(SDNode *N, MVT::ValueType VT, unsigned TargetOpc,
231                    SDOperand Op1, SDOperand Op2, SDOperand Op3, SDOperand Op4);
232  void SelectNodeTo(SDNode *N, MVT::ValueType VT, unsigned TargetOpc,
233                    SDOperand Op1, SDOperand Op2, SDOperand Op3, SDOperand Op4,
234                    SDOperand Op5);
235  void SelectNodeTo(SDNode *N, MVT::ValueType VT1, MVT::ValueType VT2,
236                    unsigned TargetOpc, SDOperand Op1, SDOperand Op2);
237
238  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
239                          SDOperand Op1) {
240    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1);
241  }
242  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
243                          SDOperand Op1, SDOperand Op2) {
244    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2);
245  }
246  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
247                          SDOperand Op1, SDOperand Op2, SDOperand Op3) {
248    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3);
249  }
250  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
251                          SDOperand Op1, SDOperand Op2, SDOperand Op3,
252                          SDOperand Op4) {
253    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3, Op4);
254  }
255  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
256                          SDOperand Op1, SDOperand Op2, SDOperand Op3,
257                          SDOperand Op4, SDOperand Op5) {
258    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3, Op4, Op5);
259  }
260
261  /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
262  /// This can cause recursive merging of nodes in the DAG.
263  ///
264  void ReplaceAllUsesWith(SDNode *From, SDNode *To);
265
266  void dump() const;
267
268private:
269  void RemoveNodeFromCSEMaps(SDNode *N);
270  SDNode *AddNonLeafNodeToCSEMaps(SDNode *N);
271  void DeleteNodeIfDead(SDNode *N, void *NodeSet);
272
273  /// SimplifySetCC - Try to simplify a setcc built with the specified operands
274  /// and cc.  If unable to simplify it, return a null SDOperand.
275  SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N1,
276                          SDOperand N2, ISD::CondCode Cond);
277
278  /// SimplifySelectCC - Try to simplify a select_cc built with the specified
279  /// operands and cc.  This can be used to simplify both the select_cc node,
280  /// and a select node whose first operand is a setcc.
281  SDOperand SimplifySelectCC(SDOperand N1, SDOperand N2, SDOperand N3,
282                             SDOperand N4, ISD::CondCode CC);
283
284  // Maps to auto-CSE operations.
285  std::map<std::pair<unsigned, std::pair<SDOperand, MVT::ValueType> >,
286           SDNode *> UnaryOps;
287  std::map<std::pair<unsigned, std::pair<SDOperand, SDOperand> >,
288           SDNode *> BinaryOps;
289
290  std::vector<RegisterSDNode*> RegNodes;
291  std::vector<CondCodeSDNode*> CondCodeNodes;
292
293  std::map<std::pair<SDOperand, std::pair<SDOperand, MVT::ValueType> >,
294           SDNode *> Loads;
295
296  std::map<const GlobalValue*, SDNode*> GlobalValues;
297  std::map<const GlobalValue*, SDNode*> TargetGlobalValues;
298  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> Constants;
299  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> TargetConstants;
300  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> ConstantFPs;
301  std::map<int, SDNode*> FrameIndices;
302  std::map<unsigned, SDNode*> ConstantPoolIndices;
303  std::map<MachineBasicBlock *, SDNode*> BBNodes;
304  std::vector<SDNode*> ValueTypeNodes;
305  std::map<std::string, SDNode*> ExternalSymbols;
306  std::map<std::pair<unsigned,
307                     std::pair<MVT::ValueType, std::vector<SDOperand> > >,
308           SDNode*> OneResultNodes;
309  std::map<std::pair<unsigned,
310                     std::pair<std::vector<MVT::ValueType>,
311                               std::vector<SDOperand> > >,
312           SDNode*> ArbitraryNodes;
313};
314
315template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
316  typedef SelectionDAG::allnodes_iterator nodes_iterator;
317  static nodes_iterator nodes_begin(SelectionDAG *G) {
318    return G->allnodes_begin();
319  }
320  static nodes_iterator nodes_end(SelectionDAG *G) {
321    return G->allnodes_end();
322  }
323};
324
325}
326
327#endif
328