1 //===-- llvm/Target/TargetLowering.h - Target Lowering Info -----*- 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 describes how to lower LLVM code to machine code. This has two
13 // 1. Which ValueTypes are natively supported by the target.
14 // 2. Which operations are supported for supported ValueTypes.
15 // 3. Cost thresholds for alternative implementations of certain operations.
17 // In addition it has a few other components, like information about FP
20 //===----------------------------------------------------------------------===//
22 #ifndef LLVM_TARGET_TARGETLOWERING_H
23 #define LLVM_TARGET_TARGETLOWERING_H
25 #include "llvm/Type.h"
26 #include "llvm/CodeGen/SelectionDAGNodes.h"
34 class TargetRegisterClass;
38 class MachineBasicBlock;
41 //===----------------------------------------------------------------------===//
42 /// TargetLowering - This class defines information used to lower LLVM code to
43 /// legal SelectionDAG operators that the target instruction selector can accept
46 /// This class also defines callbacks that targets must implement to lower
47 /// target-specific constructs to SelectionDAG operators.
49 class TargetLowering {
51 /// LegalizeAction - This enum indicates whether operations are valid for a
52 /// target, and if not, what action should be used to make them valid.
54 Legal, // The target natively supports this operation.
55 Promote, // This operation should be executed in a larger type.
56 Expand, // Try to expand this to other ops, otherwise use a libcall.
57 Custom // Use the LowerOperation hook to implement custom lowering.
60 enum OutOfRangeShiftAmount {
61 Undefined, // Oversized shift amounts are undefined (default).
62 Mask, // Shift amounts are auto masked (anded) to value size.
63 Extend // Oversized shift pulls in zeros or sign bits.
66 enum SetCCResultValue {
67 UndefinedSetCCResult, // SetCC returns a garbage/unknown extend.
68 ZeroOrOneSetCCResult, // SetCC returns a zero extended result.
69 ZeroOrNegativeOneSetCCResult // SetCC returns a sign extended result.
72 enum SchedPreference {
73 SchedulingForLatency, // Scheduling for shortest total latency.
74 SchedulingForRegPressure // Scheduling for lowest register pressure.
77 TargetLowering(TargetMachine &TM);
78 virtual ~TargetLowering();
80 TargetMachine &getTargetMachine() const { return TM; }
81 const TargetData *getTargetData() const { return TD; }
83 bool isLittleEndian() const { return IsLittleEndian; }
84 MVT::ValueType getPointerTy() const { return PointerTy; }
85 MVT::ValueType getShiftAmountTy() const { return ShiftAmountTy; }
86 OutOfRangeShiftAmount getShiftAmountFlavor() const {return ShiftAmtHandling; }
88 /// usesGlobalOffsetTable - Return true if this target uses a GOT for PIC
90 bool usesGlobalOffsetTable() const { return UsesGlobalOffsetTable; }
92 /// isSelectExpensive - Return true if the select operation is expensive for
94 bool isSelectExpensive() const { return SelectIsExpensive; }
96 /// isIntDivCheap() - Return true if integer divide is usually cheaper than
97 /// a sequence of several shifts, adds, and multiplies for this target.
98 bool isIntDivCheap() const { return IntDivIsCheap; }
100 /// isPow2DivCheap() - Return true if pow2 div is cheaper than a chain of
102 bool isPow2DivCheap() const { return Pow2DivIsCheap; }
104 /// getSetCCResultTy - Return the ValueType of the result of setcc operations.
106 MVT::ValueType getSetCCResultTy() const { return SetCCResultTy; }
108 /// getSetCCResultContents - For targets without boolean registers, this flag
109 /// returns information about the contents of the high-bits in the setcc
111 SetCCResultValue getSetCCResultContents() const { return SetCCResultContents;}
113 /// getSchedulingPreference - Return target scheduling preference.
114 SchedPreference getSchedulingPreference() const {
115 return SchedPreferenceInfo;
118 /// getRegClassFor - Return the register class that should be used for the
119 /// specified value type. This may only be called on legal types.
120 TargetRegisterClass *getRegClassFor(MVT::ValueType VT) const {
121 TargetRegisterClass *RC = RegClassForVT[VT];
122 assert(RC && "This value type is not natively supported!");
126 /// isTypeLegal - Return true if the target has native support for the
127 /// specified value type. This means that it has a register that directly
128 /// holds it without promotions or expansions.
129 bool isTypeLegal(MVT::ValueType VT) const {
130 return RegClassForVT[VT] != 0;
133 class ValueTypeActionImpl {
134 /// ValueTypeActions - This is a bitvector that contains two bits for each
135 /// value type, where the two bits correspond to the LegalizeAction enum.
136 /// This can be queried with "getTypeAction(VT)".
137 uint32_t ValueTypeActions[2];
139 ValueTypeActionImpl() {
140 ValueTypeActions[0] = ValueTypeActions[1] = 0;
142 ValueTypeActionImpl(const ValueTypeActionImpl &RHS) {
143 ValueTypeActions[0] = RHS.ValueTypeActions[0];
144 ValueTypeActions[1] = RHS.ValueTypeActions[1];
147 LegalizeAction getTypeAction(MVT::ValueType VT) const {
148 return (LegalizeAction)((ValueTypeActions[VT>>4] >> ((2*VT) & 31)) & 3);
150 void setTypeAction(MVT::ValueType VT, LegalizeAction Action) {
151 assert(unsigned(VT >> 4) <
152 sizeof(ValueTypeActions)/sizeof(ValueTypeActions[0]));
153 ValueTypeActions[VT>>4] |= Action << ((VT*2) & 31);
157 const ValueTypeActionImpl &getValueTypeActions() const {
158 return ValueTypeActions;
161 /// getTypeAction - Return how we should legalize values of this type, either
162 /// it is already legal (return 'Legal') or we need to promote it to a larger
163 /// type (return 'Promote'), or we need to expand it into multiple registers
164 /// of smaller integer type (return 'Expand'). 'Custom' is not an option.
165 LegalizeAction getTypeAction(MVT::ValueType VT) const {
166 return ValueTypeActions.getTypeAction(VT);
169 /// getTypeToTransformTo - For types supported by the target, this is an
170 /// identity function. For types that must be promoted to larger types, this
171 /// returns the larger type to promote to. For integer types that are larger
172 /// than the largest integer register, this contains one step in the expansion
173 /// to get to the smaller register. For illegal floating point types, this
174 /// returns the integer type to transform to.
175 MVT::ValueType getTypeToTransformTo(MVT::ValueType VT) const {
176 return TransformToType[VT];
179 /// getTypeToExpandTo - For types supported by the target, this is an
180 /// identity function. For types that must be expanded (i.e. integer types
181 /// that are larger than the largest integer register or illegal floating
182 /// point types), this returns the largest legal type it will be expanded to.
183 MVT::ValueType getTypeToExpandTo(MVT::ValueType VT) const {
185 switch (getTypeAction(VT)) {
189 VT = TransformToType[VT];
192 assert(false && "Type is not legal nor is it to be expanded!");
199 /// getPackedTypeBreakdown - Packed types are broken down into some number of
200 /// legal first class types. For example, <8 x float> maps to 2 MVT::v4f32
201 /// with Altivec or SSE1, or 8 promoted MVT::f64 values with the X86 FP stack.
202 /// Similarly, <2 x long> turns into 4 MVT::i32 values with both PPC and X86.
204 /// This method returns the number of registers needed, and the VT for each
205 /// register. It also returns the VT of the PackedType elements before they
206 /// are promoted/expanded.
208 unsigned getPackedTypeBreakdown(const PackedType *PTy,
209 MVT::ValueType &PTyElementVT,
210 MVT::ValueType &PTyLegalElementVT) const;
212 typedef std::vector<double>::const_iterator legal_fpimm_iterator;
213 legal_fpimm_iterator legal_fpimm_begin() const {
214 return LegalFPImmediates.begin();
216 legal_fpimm_iterator legal_fpimm_end() const {
217 return LegalFPImmediates.end();
220 /// isShuffleMaskLegal - Targets can use this to indicate that they only
221 /// support *some* VECTOR_SHUFFLE operations, those with specific masks.
222 /// By default, if a target supports the VECTOR_SHUFFLE node, all mask values
223 /// are assumed to be legal.
224 virtual bool isShuffleMaskLegal(SDOperand Mask, MVT::ValueType VT) const {
228 /// isVectorClearMaskLegal - Similar to isShuffleMaskLegal. This is
229 /// used by Targets can use this to indicate if there is a suitable
230 /// VECTOR_SHUFFLE that can be used to replace a VAND with a constant
232 virtual bool isVectorClearMaskLegal(std::vector<SDOperand> &BVOps,
234 SelectionDAG &DAG) const {
238 /// getOperationAction - Return how this operation should be treated: either
239 /// it is legal, needs to be promoted to a larger size, needs to be
240 /// expanded to some other code sequence, or the target has a custom expander
242 LegalizeAction getOperationAction(unsigned Op, MVT::ValueType VT) const {
243 return (LegalizeAction)((OpActions[Op] >> (2*VT)) & 3);
246 /// isOperationLegal - Return true if the specified operation is legal on this
248 bool isOperationLegal(unsigned Op, MVT::ValueType VT) const {
249 return getOperationAction(Op, VT) == Legal ||
250 getOperationAction(Op, VT) == Custom;
253 /// getLoadXAction - Return how this load with extension should be treated:
254 /// either it is legal, needs to be promoted to a larger size, needs to be
255 /// expanded to some other code sequence, or the target has a custom expander
257 LegalizeAction getLoadXAction(unsigned LType, MVT::ValueType VT) const {
258 return (LegalizeAction)((LoadXActions[LType] >> (2*VT)) & 3);
261 /// isLoadXLegal - Return true if the specified load with extension is legal
263 bool isLoadXLegal(unsigned LType, MVT::ValueType VT) const {
264 return getLoadXAction(LType, VT) == Legal ||
265 getLoadXAction(LType, VT) == Custom;
268 /// getStoreXAction - Return how this store with truncation should be treated:
269 /// either it is legal, needs to be promoted to a larger size, needs to be
270 /// expanded to some other code sequence, or the target has a custom expander
272 LegalizeAction getStoreXAction(MVT::ValueType VT) const {
273 return (LegalizeAction)((StoreXActions >> (2*VT)) & 3);
276 /// isStoreXLegal - Return true if the specified store with truncation is
277 /// legal on this target.
278 bool isStoreXLegal(MVT::ValueType VT) const {
279 return getStoreXAction(VT) == Legal || getStoreXAction(VT) == Custom;
282 /// getIndexedLoadAction - Return how the indexed load should be treated:
283 /// either it is legal, needs to be promoted to a larger size, needs to be
284 /// expanded to some other code sequence, or the target has a custom expander
287 getIndexedLoadAction(unsigned IdxMode, MVT::ValueType VT) const {
288 return (LegalizeAction)((IndexedModeActions[0][IdxMode] >> (2*VT)) & 3);
291 /// isIndexedLoadLegal - Return true if the specified indexed load is legal
293 bool isIndexedLoadLegal(unsigned IdxMode, MVT::ValueType VT) const {
294 return getIndexedLoadAction(IdxMode, VT) == Legal ||
295 getIndexedLoadAction(IdxMode, VT) == Custom;
298 /// getIndexedStoreAction - Return how the indexed store should be treated:
299 /// either it is legal, needs to be promoted to a larger size, needs to be
300 /// expanded to some other code sequence, or the target has a custom expander
303 getIndexedStoreAction(unsigned IdxMode, MVT::ValueType VT) const {
304 return (LegalizeAction)((IndexedModeActions[1][IdxMode] >> (2*VT)) & 3);
307 /// isIndexedStoreLegal - Return true if the specified indexed load is legal
309 bool isIndexedStoreLegal(unsigned IdxMode, MVT::ValueType VT) const {
310 return getIndexedStoreAction(IdxMode, VT) == Legal ||
311 getIndexedStoreAction(IdxMode, VT) == Custom;
314 /// getTypeToPromoteTo - If the action for this operation is to promote, this
315 /// method returns the ValueType to promote to.
316 MVT::ValueType getTypeToPromoteTo(unsigned Op, MVT::ValueType VT) const {
317 assert(getOperationAction(Op, VT) == Promote &&
318 "This operation isn't promoted!");
320 // See if this has an explicit type specified.
321 std::map<std::pair<unsigned, MVT::ValueType>,
322 MVT::ValueType>::const_iterator PTTI =
323 PromoteToType.find(std::make_pair(Op, VT));
324 if (PTTI != PromoteToType.end()) return PTTI->second;
326 assert((MVT::isInteger(VT) || MVT::isFloatingPoint(VT)) &&
327 "Cannot autopromote this type, add it with AddPromotedToType.");
329 MVT::ValueType NVT = VT;
331 NVT = (MVT::ValueType)(NVT+1);
332 assert(MVT::isInteger(NVT) == MVT::isInteger(VT) && NVT != MVT::isVoid &&
333 "Didn't find type to promote to!");
334 } while (!isTypeLegal(NVT) ||
335 getOperationAction(Op, NVT) == Promote);
339 /// getValueType - Return the MVT::ValueType corresponding to this LLVM type.
340 /// This is fixed by the LLVM operations except for the pointer size.
341 MVT::ValueType getValueType(const Type *Ty) const {
342 switch (Ty->getTypeID()) {
343 default: assert(0 && "Unknown type!");
344 case Type::VoidTyID: return MVT::isVoid;
345 case Type::Int1TyID: return MVT::i1;
346 case Type::Int8TyID: return MVT::i8;
347 case Type::Int16TyID: return MVT::i16;
348 case Type::Int32TyID: return MVT::i32;
349 case Type::Int64TyID: return MVT::i64;
350 case Type::FloatTyID: return MVT::f32;
351 case Type::DoubleTyID: return MVT::f64;
352 case Type::PointerTyID: return PointerTy;
353 case Type::PackedTyID: return MVT::Vector;
357 /// getNumElements - Return the number of registers that this ValueType will
358 /// eventually require. This is one for any types promoted to live in larger
359 /// registers, but may be more than one for types (like i64) that are split
361 unsigned getNumElements(MVT::ValueType VT) const {
362 return NumElementsForVT[VT];
365 /// hasTargetDAGCombine - If true, the target has custom DAG combine
366 /// transformations that it can perform for the specified node.
367 bool hasTargetDAGCombine(ISD::NodeType NT) const {
368 return TargetDAGCombineArray[NT >> 3] & (1 << (NT&7));
371 /// This function returns the maximum number of store operations permitted
372 /// to replace a call to llvm.memset. The value is set by the target at the
373 /// performance threshold for such a replacement.
374 /// @brief Get maximum # of store operations permitted for llvm.memset
375 unsigned getMaxStoresPerMemset() const { return maxStoresPerMemset; }
377 /// This function returns the maximum number of store operations permitted
378 /// to replace a call to llvm.memcpy. The value is set by the target at the
379 /// performance threshold for such a replacement.
380 /// @brief Get maximum # of store operations permitted for llvm.memcpy
381 unsigned getMaxStoresPerMemcpy() const { return maxStoresPerMemcpy; }
383 /// This function returns the maximum number of store operations permitted
384 /// to replace a call to llvm.memmove. The value is set by the target at the
385 /// performance threshold for such a replacement.
386 /// @brief Get maximum # of store operations permitted for llvm.memmove
387 unsigned getMaxStoresPerMemmove() const { return maxStoresPerMemmove; }
389 /// This function returns true if the target allows unaligned memory accesses.
390 /// This is used, for example, in situations where an array copy/move/set is
391 /// converted to a sequence of store operations. It's use helps to ensure that
392 /// such replacements don't generate code that causes an alignment error
393 /// (trap) on the target machine.
394 /// @brief Determine if the target supports unaligned memory accesses.
395 bool allowsUnalignedMemoryAccesses() const {
396 return allowUnalignedMemoryAccesses;
399 /// usesUnderscoreSetJmp - Determine if we should use _setjmp or setjmp
400 /// to implement llvm.setjmp.
401 bool usesUnderscoreSetJmp() const {
402 return UseUnderscoreSetJmp;
405 /// usesUnderscoreLongJmp - Determine if we should use _longjmp or longjmp
406 /// to implement llvm.longjmp.
407 bool usesUnderscoreLongJmp() const {
408 return UseUnderscoreLongJmp;
411 /// getStackPointerRegisterToSaveRestore - If a physical register, this
412 /// specifies the register that llvm.savestack/llvm.restorestack should save
414 unsigned getStackPointerRegisterToSaveRestore() const {
415 return StackPointerRegisterToSaveRestore;
418 /// getJumpBufSize - returns the target's jmp_buf size in bytes (if never
419 /// set, the default is 200)
420 unsigned getJumpBufSize() const {
424 /// getJumpBufAlignment - returns the target's jmp_buf alignment in bytes
425 /// (if never set, the default is 0)
426 unsigned getJumpBufAlignment() const {
427 return JumpBufAlignment;
430 /// getPreIndexedAddressParts - returns true by value, base pointer and
431 /// offset pointer and addressing mode by reference if the node's address
432 /// can be legally represented as pre-indexed load / store address.
433 virtual bool getPreIndexedAddressParts(SDNode *N, SDOperand &Base,
435 ISD::MemIndexedMode &AM,
440 /// getPostIndexedAddressParts - returns true by value, base pointer and
441 /// offset pointer and addressing mode by reference if this node can be
442 /// combined with a load / store to form a post-indexed load / store.
443 virtual bool getPostIndexedAddressParts(SDNode *N, SDNode *Op,
444 SDOperand &Base, SDOperand &Offset,
445 ISD::MemIndexedMode &AM,
450 //===--------------------------------------------------------------------===//
451 // TargetLowering Optimization Methods
454 /// TargetLoweringOpt - A convenience struct that encapsulates a DAG, and two
455 /// SDOperands for returning information from TargetLowering to its clients
456 /// that want to combine
457 struct TargetLoweringOpt {
462 TargetLoweringOpt(SelectionDAG &InDAG) : DAG(InDAG) {}
464 bool CombineTo(SDOperand O, SDOperand N) {
470 /// ShrinkDemandedConstant - Check to see if the specified operand of the
471 /// specified instruction is a constant integer. If so, check to see if there
472 /// are any bits set in the constant that are not demanded. If so, shrink the
473 /// constant and return true.
474 bool ShrinkDemandedConstant(SDOperand Op, uint64_t Demanded);
477 /// MaskedValueIsZero - Return true if 'Op & Mask' is known to be zero. We
478 /// use this predicate to simplify operations downstream. Op and Mask are
479 /// known to be the same type.
480 bool MaskedValueIsZero(SDOperand Op, uint64_t Mask, unsigned Depth = 0)
483 /// ComputeMaskedBits - Determine which of the bits specified in Mask are
484 /// known to be either zero or one and return them in the KnownZero/KnownOne
485 /// bitsets. This code only analyzes bits in Mask, in order to short-circuit
486 /// processing. Targets can implement the computeMaskedBitsForTargetNode
487 /// method, to allow target nodes to be understood.
488 void ComputeMaskedBits(SDOperand Op, uint64_t Mask, uint64_t &KnownZero,
489 uint64_t &KnownOne, unsigned Depth = 0) const;
491 /// SimplifyDemandedBits - Look at Op. At this point, we know that only the
492 /// DemandedMask bits of the result of Op are ever used downstream. If we can
493 /// use this information to simplify Op, create a new simplified DAG node and
494 /// return true, returning the original and new nodes in Old and New.
495 /// Otherwise, analyze the expression and return a mask of KnownOne and
496 /// KnownZero bits for the expression (used to simplify the caller).
497 /// The KnownZero/One bits may only be accurate for those bits in the
499 bool SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
500 uint64_t &KnownZero, uint64_t &KnownOne,
501 TargetLoweringOpt &TLO, unsigned Depth = 0) const;
503 /// computeMaskedBitsForTargetNode - Determine which of the bits specified in
504 /// Mask are known to be either zero or one and return them in the
505 /// KnownZero/KnownOne bitsets.
506 virtual void computeMaskedBitsForTargetNode(const SDOperand Op,
510 unsigned Depth = 0) const;
512 /// ComputeNumSignBits - Return the number of times the sign bit of the
513 /// register is replicated into the other bits. We know that at least 1 bit
514 /// is always equal to the sign bit (itself), but other cases can give us
515 /// information. For example, immediately after an "SRA X, 2", we know that
516 /// the top 3 bits are all equal to each other, so we return 3.
517 unsigned ComputeNumSignBits(SDOperand Op, unsigned Depth = 0) const;
519 /// ComputeNumSignBitsForTargetNode - This method can be implemented by
520 /// targets that want to expose additional information about sign bits to the
522 virtual unsigned ComputeNumSignBitsForTargetNode(SDOperand Op,
523 unsigned Depth = 0) const;
525 struct DAGCombinerInfo {
526 void *DC; // The DAG Combiner object.
531 DAGCombinerInfo(SelectionDAG &dag, bool bl, void *dc)
532 : DC(dc), BeforeLegalize(bl), DAG(dag) {}
534 bool isBeforeLegalize() const { return BeforeLegalize; }
536 void AddToWorklist(SDNode *N);
537 SDOperand CombineTo(SDNode *N, const std::vector<SDOperand> &To);
538 SDOperand CombineTo(SDNode *N, SDOperand Res);
539 SDOperand CombineTo(SDNode *N, SDOperand Res0, SDOperand Res1);
542 /// PerformDAGCombine - This method will be invoked for all target nodes and
543 /// for any target-independent nodes that the target has registered with
546 /// The semantics are as follows:
548 /// SDOperand.Val == 0 - No change was made
549 /// SDOperand.Val == N - N was replaced, is dead, and is already handled.
550 /// otherwise - N should be replaced by the returned Operand.
552 /// In addition, methods provided by DAGCombinerInfo may be used to perform
553 /// more complex transformations.
555 virtual SDOperand PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
557 //===--------------------------------------------------------------------===//
558 // TargetLowering Configuration Methods - These methods should be invoked by
559 // the derived class constructor to configure this object for the target.
563 /// setUsesGlobalOffsetTable - Specify that this target does or doesn't use a
564 /// GOT for PC-relative code.
565 void setUsesGlobalOffsetTable(bool V) { UsesGlobalOffsetTable = V; }
567 /// setShiftAmountType - Describe the type that should be used for shift
568 /// amounts. This type defaults to the pointer type.
569 void setShiftAmountType(MVT::ValueType VT) { ShiftAmountTy = VT; }
571 /// setSetCCResultType - Describe the type that shoudl be used as the result
572 /// of a setcc operation. This defaults to the pointer type.
573 void setSetCCResultType(MVT::ValueType VT) { SetCCResultTy = VT; }
575 /// setSetCCResultContents - Specify how the target extends the result of a
576 /// setcc operation in a register.
577 void setSetCCResultContents(SetCCResultValue Ty) { SetCCResultContents = Ty; }
579 /// setSchedulingPreference - Specify the target scheduling preference.
580 void setSchedulingPreference(SchedPreference Pref) {
581 SchedPreferenceInfo = Pref;
584 /// setShiftAmountFlavor - Describe how the target handles out of range shift
586 void setShiftAmountFlavor(OutOfRangeShiftAmount OORSA) {
587 ShiftAmtHandling = OORSA;
590 /// setUseUnderscoreSetJmp - Indicate whether this target prefers to
591 /// use _setjmp to implement llvm.setjmp or the non _ version.
592 /// Defaults to false.
593 void setUseUnderscoreSetJmp(bool Val) {
594 UseUnderscoreSetJmp = Val;
597 /// setUseUnderscoreLongJmp - Indicate whether this target prefers to
598 /// use _longjmp to implement llvm.longjmp or the non _ version.
599 /// Defaults to false.
600 void setUseUnderscoreLongJmp(bool Val) {
601 UseUnderscoreLongJmp = Val;
604 /// setStackPointerRegisterToSaveRestore - If set to a physical register, this
605 /// specifies the register that llvm.savestack/llvm.restorestack should save
607 void setStackPointerRegisterToSaveRestore(unsigned R) {
608 StackPointerRegisterToSaveRestore = R;
611 /// SelectIsExpensive - Tells the code generator not to expand operations
612 /// into sequences that use the select operations if possible.
613 void setSelectIsExpensive() { SelectIsExpensive = true; }
615 /// setIntDivIsCheap - Tells the code generator that integer divide is
616 /// expensive, and if possible, should be replaced by an alternate sequence
617 /// of instructions not containing an integer divide.
618 void setIntDivIsCheap(bool isCheap = true) { IntDivIsCheap = isCheap; }
620 /// setPow2DivIsCheap - Tells the code generator that it shouldn't generate
621 /// srl/add/sra for a signed divide by power of two, and let the target handle
623 void setPow2DivIsCheap(bool isCheap = true) { Pow2DivIsCheap = isCheap; }
625 /// addRegisterClass - Add the specified register class as an available
626 /// regclass for the specified value type. This indicates the selector can
627 /// handle values of that class natively.
628 void addRegisterClass(MVT::ValueType VT, TargetRegisterClass *RC) {
629 AvailableRegClasses.push_back(std::make_pair(VT, RC));
630 RegClassForVT[VT] = RC;
633 /// computeRegisterProperties - Once all of the register classes are added,
634 /// this allows us to compute derived properties we expose.
635 void computeRegisterProperties();
637 /// setOperationAction - Indicate that the specified operation does not work
638 /// with the specified type and indicate what to do about it.
639 void setOperationAction(unsigned Op, MVT::ValueType VT,
640 LegalizeAction Action) {
641 assert(VT < 32 && Op < sizeof(OpActions)/sizeof(OpActions[0]) &&
642 "Table isn't big enough!");
643 OpActions[Op] &= ~(uint64_t(3UL) << VT*2);
644 OpActions[Op] |= (uint64_t)Action << VT*2;
647 /// setLoadXAction - Indicate that the specified load with extension does not
648 /// work with the with specified type and indicate what to do about it.
649 void setLoadXAction(unsigned ExtType, MVT::ValueType VT,
650 LegalizeAction Action) {
651 assert(VT < 32 && ExtType < sizeof(LoadXActions)/sizeof(LoadXActions[0]) &&
652 "Table isn't big enough!");
653 LoadXActions[ExtType] &= ~(uint64_t(3UL) << VT*2);
654 LoadXActions[ExtType] |= (uint64_t)Action << VT*2;
657 /// setStoreXAction - Indicate that the specified store with truncation does
658 /// not work with the with specified type and indicate what to do about it.
659 void setStoreXAction(MVT::ValueType VT, LegalizeAction Action) {
660 assert(VT < 32 && "Table isn't big enough!");
661 StoreXActions &= ~(uint64_t(3UL) << VT*2);
662 StoreXActions |= (uint64_t)Action << VT*2;
665 /// setIndexedLoadAction - Indicate that the specified indexed load does or
666 /// does not work with the with specified type and indicate what to do abort
667 /// it. NOTE: All indexed mode loads are initialized to Expand in
668 /// TargetLowering.cpp
669 void setIndexedLoadAction(unsigned IdxMode, MVT::ValueType VT,
670 LegalizeAction Action) {
671 assert(VT < 32 && IdxMode <
672 sizeof(IndexedModeActions[0]) / sizeof(IndexedModeActions[0][0]) &&
673 "Table isn't big enough!");
674 IndexedModeActions[0][IdxMode] &= ~(uint64_t(3UL) << VT*2);
675 IndexedModeActions[0][IdxMode] |= (uint64_t)Action << VT*2;
678 /// setIndexedStoreAction - Indicate that the specified indexed store does or
679 /// does not work with the with specified type and indicate what to do about
680 /// it. NOTE: All indexed mode stores are initialized to Expand in
681 /// TargetLowering.cpp
682 void setIndexedStoreAction(unsigned IdxMode, MVT::ValueType VT,
683 LegalizeAction Action) {
684 assert(VT < 32 && IdxMode <
685 sizeof(IndexedModeActions[1]) / sizeof(IndexedModeActions[1][0]) &&
686 "Table isn't big enough!");
687 IndexedModeActions[1][IdxMode] &= ~(uint64_t(3UL) << VT*2);
688 IndexedModeActions[1][IdxMode] |= (uint64_t)Action << VT*2;
691 /// AddPromotedToType - If Opc/OrigVT is specified as being promoted, the
692 /// promotion code defaults to trying a larger integer/fp until it can find
693 /// one that works. If that default is insufficient, this method can be used
694 /// by the target to override the default.
695 void AddPromotedToType(unsigned Opc, MVT::ValueType OrigVT,
696 MVT::ValueType DestVT) {
697 PromoteToType[std::make_pair(Opc, OrigVT)] = DestVT;
700 /// addLegalFPImmediate - Indicate that this target can instruction select
701 /// the specified FP immediate natively.
702 void addLegalFPImmediate(double Imm) {
703 LegalFPImmediates.push_back(Imm);
706 /// setTargetDAGCombine - Targets should invoke this method for each target
707 /// independent node that they want to provide a custom DAG combiner for by
708 /// implementing the PerformDAGCombine virtual method.
709 void setTargetDAGCombine(ISD::NodeType NT) {
710 TargetDAGCombineArray[NT >> 3] |= 1 << (NT&7);
713 /// setJumpBufSize - Set the target's required jmp_buf buffer size (in
714 /// bytes); default is 200
715 void setJumpBufSize(unsigned Size) {
719 /// setJumpBufAlignment - Set the target's required jmp_buf buffer
720 /// alignment (in bytes); default is 0
721 void setJumpBufAlignment(unsigned Align) {
722 JumpBufAlignment = Align;
727 //===--------------------------------------------------------------------===//
728 // Lowering methods - These methods must be implemented by targets so that
729 // the SelectionDAGLowering code knows how to lower these.
732 /// LowerArguments - This hook must be implemented to indicate how we should
733 /// lower the arguments for the specified function, into the specified DAG.
734 virtual std::vector<SDOperand>
735 LowerArguments(Function &F, SelectionDAG &DAG);
737 /// LowerCallTo - This hook lowers an abstract call to a function into an
738 /// actual call. This returns a pair of operands. The first element is the
739 /// return value for the function (if RetTy is not VoidTy). The second
740 /// element is the outgoing token chain.
741 struct ArgListEntry {
746 typedef std::vector<ArgListEntry> ArgListTy;
747 virtual std::pair<SDOperand, SDOperand>
748 LowerCallTo(SDOperand Chain, const Type *RetTy, bool RetTyIsSigned,
749 bool isVarArg, unsigned CallingConv, bool isTailCall,
750 SDOperand Callee, ArgListTy &Args, SelectionDAG &DAG);
752 /// LowerFrameReturnAddress - This hook lowers a call to llvm.returnaddress or
753 /// llvm.frameaddress (depending on the value of the first argument). The
754 /// return values are the result pointer and the resultant token chain. If
755 /// not implemented, both of these intrinsics will return null.
756 virtual std::pair<SDOperand, SDOperand>
757 LowerFrameReturnAddress(bool isFrameAddr, SDOperand Chain, unsigned Depth,
760 /// LowerOperation - This callback is invoked for operations that are
761 /// unsupported by the target, which are registered to use 'custom' lowering,
762 /// and whose defined values are all legal.
763 /// If the target has no operations that require custom lowering, it need not
764 /// implement this. The default implementation of this aborts.
765 virtual SDOperand LowerOperation(SDOperand Op, SelectionDAG &DAG);
767 /// CustomPromoteOperation - This callback is invoked for operations that are
768 /// unsupported by the target, are registered to use 'custom' lowering, and
769 /// whose type needs to be promoted.
770 virtual SDOperand CustomPromoteOperation(SDOperand Op, SelectionDAG &DAG);
772 /// getTargetNodeName() - This method returns the name of a target specific
774 virtual const char *getTargetNodeName(unsigned Opcode) const;
776 //===--------------------------------------------------------------------===//
777 // Inline Asm Support hooks
780 enum ConstraintType {
781 C_Register, // Constraint represents a single register.
782 C_RegisterClass, // Constraint represents one or more registers.
783 C_Memory, // Memory constraint.
784 C_Other, // Something else.
785 C_Unknown // Unsupported constraint.
788 /// getConstraintType - Given a constraint letter, return the type of
789 /// constraint it is for this target.
790 virtual ConstraintType getConstraintType(char ConstraintLetter) const;
793 /// getRegClassForInlineAsmConstraint - Given a constraint letter (e.g. "r"),
794 /// return a list of registers that can be used to satisfy the constraint.
795 /// This should only be used for C_RegisterClass constraints.
796 virtual std::vector<unsigned>
797 getRegClassForInlineAsmConstraint(const std::string &Constraint,
798 MVT::ValueType VT) const;
800 /// getRegForInlineAsmConstraint - Given a physical register constraint (e.g.
801 /// {edx}), return the register number and the register class for the
804 /// Given a register class constraint, like 'r', if this corresponds directly
805 /// to an LLVM register class, return a register of 0 and the register class
808 /// This should only be used for C_Register constraints. On error,
809 /// this returns a register number of 0 and a null register class pointer..
810 virtual std::pair<unsigned, const TargetRegisterClass*>
811 getRegForInlineAsmConstraint(const std::string &Constraint,
812 MVT::ValueType VT) const;
815 /// isOperandValidForConstraint - Return the specified operand (possibly
816 /// modified) if the specified SDOperand is valid for the specified target
817 /// constraint letter, otherwise return null.
819 isOperandValidForConstraint(SDOperand Op, char ConstraintLetter,
822 //===--------------------------------------------------------------------===//
826 // InsertAtEndOfBasicBlock - This method should be implemented by targets that
827 // mark instructions with the 'usesCustomDAGSchedInserter' flag. These
828 // instructions are special in various ways, which require special support to
829 // insert. The specified MachineInstr is created but not inserted into any
830 // basic blocks, and the scheduler passes ownership of it to this method.
831 virtual MachineBasicBlock *InsertAtEndOfBasicBlock(MachineInstr *MI,
832 MachineBasicBlock *MBB);
834 //===--------------------------------------------------------------------===//
835 // Loop Strength Reduction hooks
838 /// isLegalAddressImmediate - Return true if the integer value or GlobalValue
839 /// can be used as the offset of the target addressing mode.
840 virtual bool isLegalAddressImmediate(int64_t V) const;
841 virtual bool isLegalAddressImmediate(GlobalValue *GV) const;
843 typedef std::vector<unsigned>::const_iterator legal_am_scale_iterator;
844 legal_am_scale_iterator legal_am_scale_begin() const {
845 return LegalAddressScales.begin();
847 legal_am_scale_iterator legal_am_scale_end() const {
848 return LegalAddressScales.end();
851 //===--------------------------------------------------------------------===//
852 // Div utility functions
854 SDOperand BuildSDIV(SDNode *N, SelectionDAG &DAG,
855 std::vector<SDNode*>* Created) const;
856 SDOperand BuildUDIV(SDNode *N, SelectionDAG &DAG,
857 std::vector<SDNode*>* Created) const;
861 /// addLegalAddressScale - Add a integer (> 1) value which can be used as
862 /// scale in the target addressing mode. Note: the ordering matters so the
863 /// least efficient ones should be entered first.
864 void addLegalAddressScale(unsigned Scale) {
865 LegalAddressScales.push_back(Scale);
869 std::vector<unsigned> LegalAddressScales;
872 const TargetData *TD;
874 /// IsLittleEndian - True if this is a little endian target.
878 /// PointerTy - The type to use for pointers, usually i32 or i64.
880 MVT::ValueType PointerTy;
882 /// UsesGlobalOffsetTable - True if this target uses a GOT for PIC codegen.
884 bool UsesGlobalOffsetTable;
886 /// ShiftAmountTy - The type to use for shift amounts, usually i8 or whatever
888 MVT::ValueType ShiftAmountTy;
890 OutOfRangeShiftAmount ShiftAmtHandling;
892 /// SelectIsExpensive - Tells the code generator not to expand operations
893 /// into sequences that use the select operations if possible.
894 bool SelectIsExpensive;
896 /// IntDivIsCheap - Tells the code generator not to expand integer divides by
897 /// constants into a sequence of muls, adds, and shifts. This is a hack until
898 /// a real cost model is in place. If we ever optimize for size, this will be
899 /// set to true unconditionally.
902 /// Pow2DivIsCheap - Tells the code generator that it shouldn't generate
903 /// srl/add/sra for a signed divide by power of two, and let the target handle
907 /// SetCCResultTy - The type that SetCC operations use. This defaults to the
909 MVT::ValueType SetCCResultTy;
911 /// SetCCResultContents - Information about the contents of the high-bits in
912 /// the result of a setcc comparison operation.
913 SetCCResultValue SetCCResultContents;
915 /// SchedPreferenceInfo - The target scheduling preference: shortest possible
916 /// total cycles or lowest register usage.
917 SchedPreference SchedPreferenceInfo;
919 /// UseUnderscoreSetJmp - This target prefers to use _setjmp to implement
920 /// llvm.setjmp. Defaults to false.
921 bool UseUnderscoreSetJmp;
923 /// UseUnderscoreLongJmp - This target prefers to use _longjmp to implement
924 /// llvm.longjmp. Defaults to false.
925 bool UseUnderscoreLongJmp;
927 /// JumpBufSize - The size, in bytes, of the target's jmp_buf buffers
928 unsigned JumpBufSize;
930 /// JumpBufAlignment - The alignment, in bytes, of the target's jmp_buf
932 unsigned JumpBufAlignment;
934 /// StackPointerRegisterToSaveRestore - If set to a physical register, this
935 /// specifies the register that llvm.savestack/llvm.restorestack should save
937 unsigned StackPointerRegisterToSaveRestore;
939 /// RegClassForVT - This indicates the default register class to use for
940 /// each ValueType the target supports natively.
941 TargetRegisterClass *RegClassForVT[MVT::LAST_VALUETYPE];
942 unsigned char NumElementsForVT[MVT::LAST_VALUETYPE];
944 /// TransformToType - For any value types we are promoting or expanding, this
945 /// contains the value type that we are changing to. For Expanded types, this
946 /// contains one step of the expand (e.g. i64 -> i32), even if there are
947 /// multiple steps required (e.g. i64 -> i16). For types natively supported
948 /// by the system, this holds the same type (e.g. i32 -> i32).
949 MVT::ValueType TransformToType[MVT::LAST_VALUETYPE];
951 /// OpActions - For each operation and each value type, keep a LegalizeAction
952 /// that indicates how instruction selection should deal with the operation.
953 /// Most operations are Legal (aka, supported natively by the target), but
954 /// operations that are not should be described. Note that operations on
955 /// non-legal value types are not described here.
956 uint64_t OpActions[156];
958 /// LoadXActions - For each load of load extension type and each value type,
959 /// keep a LegalizeAction that indicates how instruction selection should deal
961 uint64_t LoadXActions[ISD::LAST_LOADX_TYPE];
963 /// StoreXActions - For each store with truncation of each value type, keep a
964 /// LegalizeAction that indicates how instruction selection should deal with
966 uint64_t StoreXActions;
968 /// IndexedModeActions - For each indexed mode and each value type, keep a
969 /// pair of LegalizeAction that indicates how instruction selection should
970 /// deal with the load / store.
971 uint64_t IndexedModeActions[2][ISD::LAST_INDEXED_MODE];
973 ValueTypeActionImpl ValueTypeActions;
975 std::vector<double> LegalFPImmediates;
977 std::vector<std::pair<MVT::ValueType,
978 TargetRegisterClass*> > AvailableRegClasses;
980 /// TargetDAGCombineArray - Targets can specify ISD nodes that they would
981 /// like PerformDAGCombine callbacks for by calling setTargetDAGCombine(),
982 /// which sets a bit in this array.
983 unsigned char TargetDAGCombineArray[156/(sizeof(unsigned char)*8)];
985 /// PromoteToType - For operations that must be promoted to a specific type,
986 /// this holds the destination type. This map should be sparse, so don't hold
989 /// Targets add entries to this map with AddPromotedToType(..), clients access
990 /// this with getTypeToPromoteTo(..).
991 std::map<std::pair<unsigned, MVT::ValueType>, MVT::ValueType> PromoteToType;
994 /// When lowering %llvm.memset this field specifies the maximum number of
995 /// store operations that may be substituted for the call to memset. Targets
996 /// must set this value based on the cost threshold for that target. Targets
997 /// should assume that the memset will be done using as many of the largest
998 /// store operations first, followed by smaller ones, if necessary, per
999 /// alignment restrictions. For example, storing 9 bytes on a 32-bit machine
1000 /// with 16-bit alignment would result in four 2-byte stores and one 1-byte
1001 /// store. This only applies to setting a constant array of a constant size.
1002 /// @brief Specify maximum number of store instructions per memset call.
1003 unsigned maxStoresPerMemset;
1005 /// When lowering %llvm.memcpy this field specifies the maximum number of
1006 /// store operations that may be substituted for a call to memcpy. Targets
1007 /// must set this value based on the cost threshold for that target. Targets
1008 /// should assume that the memcpy will be done using as many of the largest
1009 /// store operations first, followed by smaller ones, if necessary, per
1010 /// alignment restrictions. For example, storing 7 bytes on a 32-bit machine
1011 /// with 32-bit alignment would result in one 4-byte store, a one 2-byte store
1012 /// and one 1-byte store. This only applies to copying a constant array of
1014 /// @brief Specify maximum bytes of store instructions per memcpy call.
1015 unsigned maxStoresPerMemcpy;
1017 /// When lowering %llvm.memmove this field specifies the maximum number of
1018 /// store instructions that may be substituted for a call to memmove. Targets
1019 /// must set this value based on the cost threshold for that target. Targets
1020 /// should assume that the memmove will be done using as many of the largest
1021 /// store operations first, followed by smaller ones, if necessary, per
1022 /// alignment restrictions. For example, moving 9 bytes on a 32-bit machine
1023 /// with 8-bit alignment would result in nine 1-byte stores. This only
1024 /// applies to copying a constant array of constant size.
1025 /// @brief Specify maximum bytes of store instructions per memmove call.
1026 unsigned maxStoresPerMemmove;
1028 /// This field specifies whether the target machine permits unaligned memory
1029 /// accesses. This is used, for example, to determine the size of store
1030 /// operations when copying small arrays and other similar tasks.
1031 /// @brief Indicate whether the target permits unaligned memory accesses.
1032 bool allowUnalignedMemoryAccesses;
1034 } // end llvm namespace