1 //===-- llvm/CodeGen/SelectionDAG.h - InstSelection DAG ---------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
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.
8 //===----------------------------------------------------------------------===//
10 // This file declares the SelectionDAG class, and transitively defines the
11 // SDNode class and subclasses.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_SELECTIONDAG_H
16 #define LLVM_CODEGEN_SELECTIONDAG_H
18 #include "llvm/ADT/FoldingSet.h"
19 #include "llvm/ADT/ilist"
20 #include "llvm/CodeGen/SelectionDAGNodes.h"
32 class MachineModuleInfo;
33 class MachineFunction;
34 class MachineConstantPoolValue;
36 /// SelectionDAG class - This is used to represent a portion of an LLVM function
37 /// in a low-level Data Dependence DAG representation suitable for instruction
38 /// selection. This DAG is constructed as the first step of instruction
39 /// selection in order to allow implementation of machine specific optimizations
40 /// and code simplifications.
42 /// The representation used by the SelectionDAG is a target-independent
43 /// representation, which has some similarities to the GCC RTL representation,
44 /// but is significantly more simple, powerful, and is a graph form instead of a
50 MachineModuleInfo *MMI;
52 /// Root - The root of the entire DAG. EntryNode - The starting token.
53 SDOperand Root, EntryNode;
55 /// AllNodes - A linked list of nodes in the current DAG.
56 ilist<SDNode> AllNodes;
58 /// CSEMap - This structure is used to memoize nodes, automatically performing
59 /// CSE with existing nodes with a duplicate is requested.
60 FoldingSet<SDNode> CSEMap;
63 SelectionDAG(TargetLowering &tli, MachineFunction &mf, MachineModuleInfo *mmi)
64 : TLI(tli), MF(mf), MMI(mmi) {
65 EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
69 MachineFunction &getMachineFunction() const { return MF; }
70 const TargetMachine &getTarget() const;
71 TargetLowering &getTargetLoweringInfo() const { return TLI; }
72 MachineModuleInfo *getMachineModuleInfo() const { return MMI; }
74 /// viewGraph - Pop up a GraphViz/gv window with the DAG rendered using 'dot'.
79 std::map<const SDNode *, std::string> NodeGraphAttrs;
82 /// clearGraphAttrs - Clear all previously defined node graph attributes.
83 /// Intended to be used from a debugging tool (eg. gdb).
84 void clearGraphAttrs();
86 /// setGraphAttrs - Set graph attributes for a node. (eg. "color=red".)
88 void setGraphAttrs(const SDNode *N, const char *Attrs);
90 /// getGraphAttrs - Get graph attributes for a node. (eg. "color=red".)
91 /// Used from getNodeAttributes.
92 const std::string getGraphAttrs(const SDNode *N) const;
94 /// setGraphColor - Convenience for setting node color attribute.
96 void setGraphColor(const SDNode *N, const char *Color);
98 typedef ilist<SDNode>::const_iterator allnodes_const_iterator;
99 allnodes_const_iterator allnodes_begin() const { return AllNodes.begin(); }
100 allnodes_const_iterator allnodes_end() const { return AllNodes.end(); }
101 typedef ilist<SDNode>::iterator allnodes_iterator;
102 allnodes_iterator allnodes_begin() { return AllNodes.begin(); }
103 allnodes_iterator allnodes_end() { return AllNodes.end(); }
105 /// getRoot - Return the root tag of the SelectionDAG.
107 const SDOperand &getRoot() const { return Root; }
109 /// getEntryNode - Return the token chain corresponding to the entry of the
111 const SDOperand &getEntryNode() const { return EntryNode; }
113 /// setRoot - Set the current root tag of the SelectionDAG.
115 const SDOperand &setRoot(SDOperand N) { return Root = N; }
117 /// Combine - This iterates over the nodes in the SelectionDAG, folding
118 /// certain types of nodes together, or eliminating superfluous nodes. When
119 /// the AfterLegalize argument is set to 'true', Combine takes care not to
120 /// generate any nodes that will be illegal on the target.
121 void Combine(bool AfterLegalize, AliasAnalysis &AA);
123 /// LegalizeTypes - This transforms the SelectionDAG into a SelectionDAG that
124 /// only uses types natively supported by the target.
126 /// Note that this is an involved process that may invalidate pointers into
128 void LegalizeTypes();
130 /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
131 /// compatible with the target instruction selector, as indicated by the
132 /// TargetLowering object.
134 /// Note that this is an involved process that may invalidate pointers into
138 /// RemoveDeadNodes - This method deletes all unreachable nodes in the
140 void RemoveDeadNodes();
142 /// RemoveDeadNode - Remove the specified node from the system. If any of its
143 /// operands then becomes dead, remove them as well. The vector Deleted is
144 /// populated with nodes that are deleted.
145 void RemoveDeadNode(SDNode *N, std::vector<SDNode*> &Deleted);
147 /// DeleteNode - Remove the specified node from the system. This node must
148 /// have no referrers.
149 void DeleteNode(SDNode *N);
151 /// getVTList - Return an SDVTList that represents the list of values
153 SDVTList getVTList(MVT::ValueType VT);
154 SDVTList getVTList(MVT::ValueType VT1, MVT::ValueType VT2);
155 SDVTList getVTList(MVT::ValueType VT1, MVT::ValueType VT2,MVT::ValueType VT3);
156 SDVTList getVTList(const MVT::ValueType *VTs, unsigned NumVTs);
158 /// getNodeValueTypes - These are obsolete, use getVTList instead.
159 const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT) {
160 return getVTList(VT).VTs;
162 const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT1,
163 MVT::ValueType VT2) {
164 return getVTList(VT1, VT2).VTs;
166 const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT1,MVT::ValueType VT2,
167 MVT::ValueType VT3) {
168 return getVTList(VT1, VT2, VT3).VTs;
170 const MVT::ValueType *getNodeValueTypes(std::vector<MVT::ValueType> &VTList) {
171 return getVTList(&VTList[0], VTList.size()).VTs;
175 //===--------------------------------------------------------------------===//
176 // Node creation methods.
178 SDOperand getString(const std::string &Val);
179 SDOperand getConstant(uint64_t Val, MVT::ValueType VT, bool isTarget = false);
180 SDOperand getTargetConstant(uint64_t Val, MVT::ValueType VT) {
181 return getConstant(Val, VT, true);
183 SDOperand getConstantFP(double Val, MVT::ValueType VT, bool isTarget = false);
184 SDOperand getConstantFP(const APFloat& Val, MVT::ValueType VT,
185 bool isTarget = false);
186 SDOperand getTargetConstantFP(double Val, MVT::ValueType VT) {
187 return getConstantFP(Val, VT, true);
189 SDOperand getTargetConstantFP(const APFloat& Val, MVT::ValueType VT) {
190 return getConstantFP(Val, VT, true);
192 SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
193 int offset = 0, bool isTargetGA = false);
194 SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
196 return getGlobalAddress(GV, VT, offset, true);
198 SDOperand getFrameIndex(int FI, MVT::ValueType VT, bool isTarget = false);
199 SDOperand getTargetFrameIndex(int FI, MVT::ValueType VT) {
200 return getFrameIndex(FI, VT, true);
202 SDOperand getJumpTable(int JTI, MVT::ValueType VT, bool isTarget = false);
203 SDOperand getTargetJumpTable(int JTI, MVT::ValueType VT) {
204 return getJumpTable(JTI, VT, true);
206 SDOperand getConstantPool(Constant *C, MVT::ValueType VT,
207 unsigned Align = 0, int Offs = 0, bool isT=false);
208 SDOperand getTargetConstantPool(Constant *C, MVT::ValueType VT,
209 unsigned Align = 0, int Offset = 0) {
210 return getConstantPool(C, VT, Align, Offset, true);
212 SDOperand getConstantPool(MachineConstantPoolValue *C, MVT::ValueType VT,
213 unsigned Align = 0, int Offs = 0, bool isT=false);
214 SDOperand getTargetConstantPool(MachineConstantPoolValue *C,
215 MVT::ValueType VT, unsigned Align = 0,
217 return getConstantPool(C, VT, Align, Offset, true);
219 SDOperand getBasicBlock(MachineBasicBlock *MBB);
220 SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
221 SDOperand getTargetExternalSymbol(const char *Sym, MVT::ValueType VT);
222 SDOperand getValueType(MVT::ValueType);
223 SDOperand getRegister(unsigned Reg, MVT::ValueType VT);
225 SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
226 return getNode(ISD::CopyToReg, MVT::Other, Chain,
227 getRegister(Reg, N.getValueType()), N);
230 // This version of the getCopyToReg method takes an extra operand, which
231 // indicates that there is potentially an incoming flag value (if Flag is not
232 // null) and that there should be a flag result.
233 SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N,
235 const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
236 SDOperand Ops[] = { Chain, getRegister(Reg, N.getValueType()), N, Flag };
237 return getNode(ISD::CopyToReg, VTs, 2, Ops, Flag.Val ? 4 : 3);
240 // Similar to last getCopyToReg() except parameter Reg is a SDOperand
241 SDOperand getCopyToReg(SDOperand Chain, SDOperand Reg, SDOperand N,
243 const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
244 SDOperand Ops[] = { Chain, Reg, N, Flag };
245 return getNode(ISD::CopyToReg, VTs, 2, Ops, Flag.Val ? 4 : 3);
248 SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
249 const MVT::ValueType *VTs = getNodeValueTypes(VT, MVT::Other);
250 SDOperand Ops[] = { Chain, getRegister(Reg, VT) };
251 return getNode(ISD::CopyFromReg, VTs, 2, Ops, 2);
254 // This version of the getCopyFromReg method takes an extra operand, which
255 // indicates that there is potentially an incoming flag value (if Flag is not
256 // null) and that there should be a flag result.
257 SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT,
259 const MVT::ValueType *VTs = getNodeValueTypes(VT, MVT::Other, MVT::Flag);
260 SDOperand Ops[] = { Chain, getRegister(Reg, VT), Flag };
261 return getNode(ISD::CopyFromReg, VTs, 3, Ops, Flag.Val ? 3 : 2);
264 SDOperand getCondCode(ISD::CondCode Cond);
266 /// getZeroExtendInReg - Return the expression required to zero extend the Op
267 /// value assuming it was the smaller SrcTy value.
268 SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
270 /// getCALLSEQ_START - Return a new CALLSEQ_START node, which always must have
271 /// a flag result (to ensure it's not CSE'd).
272 SDOperand getCALLSEQ_START(SDOperand Chain, SDOperand Op) {
273 const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
274 SDOperand Ops[] = { Chain, Op };
275 return getNode(ISD::CALLSEQ_START, VTs, 2, Ops, 2);
278 /// getNode - Gets or creates the specified node.
280 SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
281 SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
282 SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
283 SDOperand N1, SDOperand N2);
284 SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
285 SDOperand N1, SDOperand N2, SDOperand N3);
286 SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
287 SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
288 SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
289 SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
291 SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
292 const SDOperand *Ops, unsigned NumOps);
293 SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
294 const SDOperand *Ops, unsigned NumOps);
295 SDOperand getNode(unsigned Opcode, const MVT::ValueType *VTs, unsigned NumVTs,
296 const SDOperand *Ops, unsigned NumOps);
297 SDOperand getNode(unsigned Opcode, SDVTList VTs);
298 SDOperand getNode(unsigned Opcode, SDVTList VTs, SDOperand N);
299 SDOperand getNode(unsigned Opcode, SDVTList VTs,
300 SDOperand N1, SDOperand N2);
301 SDOperand getNode(unsigned Opcode, SDVTList VTs,
302 SDOperand N1, SDOperand N2, SDOperand N3);
303 SDOperand getNode(unsigned Opcode, SDVTList VTs,
304 SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
305 SDOperand getNode(unsigned Opcode, SDVTList VTs,
306 SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
308 SDOperand getNode(unsigned Opcode, SDVTList VTs,
309 const SDOperand *Ops, unsigned NumOps);
311 /// getSetCC - Helper function to make it easier to build SetCC's if you just
312 /// have an ISD::CondCode instead of an SDOperand.
314 SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
315 ISD::CondCode Cond) {
316 return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
319 /// getSelectCC - Helper function to make it easier to build SelectCC's if you
320 /// just have an ISD::CondCode instead of an SDOperand.
322 SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
323 SDOperand True, SDOperand False, ISD::CondCode Cond) {
324 return getNode(ISD::SELECT_CC, True.getValueType(), LHS, RHS, True, False,
328 /// getVAArg - VAArg produces a result and token chain, and takes a pointer
329 /// and a source value as input.
330 SDOperand getVAArg(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
333 /// getLoad - Loads are not normal binary operators: their result type is not
334 /// determined by their operands, and they produce a value AND a token chain.
336 SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
337 const Value *SV, int SVOffset, bool isVolatile=false,
338 unsigned Alignment=0);
339 SDOperand getExtLoad(ISD::LoadExtType ExtType, MVT::ValueType VT,
340 SDOperand Chain, SDOperand Ptr, const Value *SV,
341 int SVOffset, MVT::ValueType EVT, bool isVolatile=false,
342 unsigned Alignment=0);
343 SDOperand getIndexedLoad(SDOperand OrigLoad, SDOperand Base,
344 SDOperand Offset, ISD::MemIndexedMode AM);
346 /// getStore - Helper function to build ISD::STORE nodes.
348 SDOperand getStore(SDOperand Chain, SDOperand Val, SDOperand Ptr,
349 const Value *SV, int SVOffset, bool isVolatile=false,
350 unsigned Alignment=0);
351 SDOperand getTruncStore(SDOperand Chain, SDOperand Val, SDOperand Ptr,
352 const Value *SV, int SVOffset, MVT::ValueType TVT,
353 bool isVolatile=false, unsigned Alignment=0);
354 SDOperand getIndexedStore(SDOperand OrigStoe, SDOperand Base,
355 SDOperand Offset, ISD::MemIndexedMode AM);
357 // getSrcValue - construct a node to track a Value* through the backend
358 SDOperand getSrcValue(const Value* I, int offset = 0);
360 /// UpdateNodeOperands - *Mutate* the specified node in-place to have the
361 /// specified operands. If the resultant node already exists in the DAG,
362 /// this does not modify the specified node, instead it returns the node that
363 /// already exists. If the resultant node does not exist in the DAG, the
364 /// input node is returned. As a degenerate case, if you specify the same
365 /// input operands as the node already has, the input node is returned.
366 SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op);
367 SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2);
368 SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
370 SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
371 SDOperand Op3, SDOperand Op4);
372 SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
373 SDOperand Op3, SDOperand Op4, SDOperand Op5);
374 SDOperand UpdateNodeOperands(SDOperand N, SDOperand *Ops, unsigned NumOps);
376 /// SelectNodeTo - These are used for target selectors to *mutate* the
377 /// specified node to have the specified return type, Target opcode, and
378 /// operands. Note that target opcodes are stored as
379 /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field. The 0th value
380 /// of the resultant node is returned.
381 SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT);
382 SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
384 SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
385 SDOperand Op1, SDOperand Op2);
386 SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
387 SDOperand Op1, SDOperand Op2, SDOperand Op3);
388 SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
389 const SDOperand *Ops, unsigned NumOps);
390 SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
391 MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
392 SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
393 MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
397 /// getTargetNode - These are used for target selectors to create a new node
398 /// with specified return type(s), target opcode, and operands.
400 /// Note that getTargetNode returns the resultant node. If there is already a
401 /// node of the specified opcode and operands, it returns that node instead of
403 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT);
404 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
406 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
407 SDOperand Op1, SDOperand Op2);
408 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
409 SDOperand Op1, SDOperand Op2, SDOperand Op3);
410 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
411 const SDOperand *Ops, unsigned NumOps);
412 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
414 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
415 MVT::ValueType VT2, SDOperand Op1);
416 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
417 MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
418 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
419 MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
421 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
423 const SDOperand *Ops, unsigned NumOps);
424 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
425 MVT::ValueType VT2, MVT::ValueType VT3,
426 SDOperand Op1, SDOperand Op2);
427 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
428 MVT::ValueType VT2, MVT::ValueType VT3,
429 SDOperand Op1, SDOperand Op2, SDOperand Op3);
430 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
431 MVT::ValueType VT2, MVT::ValueType VT3,
432 const SDOperand *Ops, unsigned NumOps);
433 SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
434 MVT::ValueType VT2, MVT::ValueType VT3,
436 const SDOperand *Ops, unsigned NumOps);
437 SDNode *getTargetNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
438 const SDOperand *Ops, unsigned NumOps);
440 /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
441 /// This can cause recursive merging of nodes in the DAG. Use the first
442 /// version if 'From' is known to have a single result, use the second
443 /// if you have two nodes with identical results, use the third otherwise.
445 /// These methods all take an optional vector, which (if not null) is
446 /// populated with any nodes that are deleted from the SelectionDAG, due to
447 /// new equivalences that are discovered.
449 void ReplaceAllUsesWith(SDOperand From, SDOperand Op,
450 std::vector<SDNode*> *Deleted = 0);
451 void ReplaceAllUsesWith(SDNode *From, SDNode *To,
452 std::vector<SDNode*> *Deleted = 0);
453 void ReplaceAllUsesWith(SDNode *From, const SDOperand *To,
454 std::vector<SDNode*> *Deleted = 0);
456 /// ReplaceAllUsesOfValueWith - Replace any uses of From with To, leaving
457 /// uses of other values produced by From.Val alone. The Deleted vector is
458 /// handled the same was as for ReplaceAllUsesWith, but it is required for
460 void ReplaceAllUsesOfValueWith(SDOperand From, SDOperand To,
461 std::vector<SDNode*> *Deleted = 0);
463 /// AssignNodeIds - Assign a unique node id for each node in the DAG based on
464 /// their allnodes order. It returns the maximum id.
465 unsigned AssignNodeIds();
467 /// AssignTopologicalOrder - Assign a unique node id for each node in the DAG
468 /// based on their topological order. It returns the maximum id and a vector
469 /// of the SDNodes* in assigned order by reference.
470 unsigned AssignTopologicalOrder(std::vector<SDNode*> &TopOrder);
472 /// isCommutativeBinOp - Returns true if the opcode is a commutative binary
474 static bool isCommutativeBinOp(unsigned Opcode) {
488 case ISD::ADDE: return true;
489 default: return false;
495 /// FoldSetCC - Constant fold a setcc to true or false.
496 SDOperand FoldSetCC(MVT::ValueType VT, SDOperand N1,
497 SDOperand N2, ISD::CondCode Cond);
499 /// MaskedValueIsZero - Return true if 'Op & Mask' is known to be zero. We
500 /// use this predicate to simplify operations downstream. Op and Mask are
501 /// known to be the same type.
502 bool MaskedValueIsZero(SDOperand Op, uint64_t Mask, unsigned Depth = 0)
505 /// ComputeMaskedBits - Determine which of the bits specified in Mask are
506 /// known to be either zero or one and return them in the KnownZero/KnownOne
507 /// bitsets. This code only analyzes bits in Mask, in order to short-circuit
508 /// processing. Targets can implement the computeMaskedBitsForTargetNode
509 /// method in the TargetLowering class to allow target nodes to be understood.
510 void ComputeMaskedBits(SDOperand Op, uint64_t Mask, uint64_t &KnownZero,
511 uint64_t &KnownOne, unsigned Depth = 0) const;
513 /// ComputeNumSignBits - Return the number of times the sign bit of the
514 /// register is replicated into the other bits. We know that at least 1 bit
515 /// is always equal to the sign bit (itself), but other cases can give us
516 /// information. For example, immediately after an "SRA X, 2", we know that
517 /// the top 3 bits are all equal to each other, so we return 3. Targets can
518 /// implement the ComputeNumSignBitsForTarget method in the TargetLowering
519 /// class to allow target nodes to be understood.
520 unsigned ComputeNumSignBits(SDOperand Op, unsigned Depth = 0) const;
523 void RemoveNodeFromCSEMaps(SDNode *N);
524 SDNode *AddNonLeafNodeToCSEMaps(SDNode *N);
525 SDNode *FindModifiedNodeSlot(SDNode *N, SDOperand Op, void *&InsertPos);
526 SDNode *FindModifiedNodeSlot(SDNode *N, SDOperand Op1, SDOperand Op2,
528 SDNode *FindModifiedNodeSlot(SDNode *N, const SDOperand *Ops, unsigned NumOps,
531 void DeleteNodeNotInCSEMaps(SDNode *N);
533 // List of non-single value types.
534 std::list<std::vector<MVT::ValueType> > VTList;
536 // Maps to auto-CSE operations.
537 std::vector<CondCodeSDNode*> CondCodeNodes;
539 std::vector<SDNode*> ValueTypeNodes;
540 std::map<std::string, SDNode*> ExternalSymbols;
541 std::map<std::string, SDNode*> TargetExternalSymbols;
542 std::map<std::string, StringSDNode*> StringNodes;
545 template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
546 typedef SelectionDAG::allnodes_iterator nodes_iterator;
547 static nodes_iterator nodes_begin(SelectionDAG *G) {
548 return G->allnodes_begin();
550 static nodes_iterator nodes_end(SelectionDAG *G) {
551 return G->allnodes_end();
555 } // end namespace llvm