1 //===-- llvm/Target/TargetLowering.h - Target Lowering Info -----*- 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 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/CodeGen/SelectionDAGNodes.h"
26 #include "llvm/CodeGen/RuntimeLibcalls.h"
27 #include "llvm/ADT/APFloat.h"
28 #include "llvm/ADT/STLExtras.h"
37 class TargetRegisterClass;
41 class MachineBasicBlock;
44 class TargetSubtarget;
46 //===----------------------------------------------------------------------===//
47 /// TargetLowering - This class defines information used to lower LLVM code to
48 /// legal SelectionDAG operators that the target instruction selector can accept
51 /// This class also defines callbacks that targets must implement to lower
52 /// target-specific constructs to SelectionDAG operators.
54 class TargetLowering {
56 /// LegalizeAction - This enum indicates whether operations are valid for a
57 /// target, and if not, what action should be used to make them valid.
59 Legal, // The target natively supports this operation.
60 Promote, // This operation should be executed in a larger type.
61 Expand, // Try to expand this to other ops, otherwise use a libcall.
62 Custom // Use the LowerOperation hook to implement custom lowering.
65 enum OutOfRangeShiftAmount {
66 Undefined, // Oversized shift amounts are undefined (default).
67 Mask, // Shift amounts are auto masked (anded) to value size.
68 Extend // Oversized shift pulls in zeros or sign bits.
71 enum SetCCResultValue {
72 UndefinedSetCCResult, // SetCC returns a garbage/unknown extend.
73 ZeroOrOneSetCCResult, // SetCC returns a zero extended result.
74 ZeroOrNegativeOneSetCCResult // SetCC returns a sign extended result.
77 enum SchedPreference {
78 SchedulingForLatency, // Scheduling for shortest total latency.
79 SchedulingForRegPressure // Scheduling for lowest register pressure.
82 explicit TargetLowering(TargetMachine &TM);
83 virtual ~TargetLowering();
85 TargetMachine &getTargetMachine() const { return TM; }
86 const TargetData *getTargetData() const { return TD; }
88 bool isLittleEndian() const { return IsLittleEndian; }
89 MVT::ValueType getPointerTy() const { return PointerTy; }
90 MVT::ValueType getShiftAmountTy() const { return ShiftAmountTy; }
91 OutOfRangeShiftAmount getShiftAmountFlavor() const {return ShiftAmtHandling; }
93 /// usesGlobalOffsetTable - Return true if this target uses a GOT for PIC
95 bool usesGlobalOffsetTable() const { return UsesGlobalOffsetTable; }
97 /// isSelectExpensive - Return true if the select operation is expensive for
99 bool isSelectExpensive() const { return SelectIsExpensive; }
101 /// isIntDivCheap() - Return true if integer divide is usually cheaper than
102 /// a sequence of several shifts, adds, and multiplies for this target.
103 bool isIntDivCheap() const { return IntDivIsCheap; }
105 /// isPow2DivCheap() - Return true if pow2 div is cheaper than a chain of
107 bool isPow2DivCheap() const { return Pow2DivIsCheap; }
109 /// getSetCCResultTy - Return the ValueType of the result of setcc operations.
111 MVT::ValueType getSetCCResultTy() const { return SetCCResultTy; }
113 /// getSetCCResultContents - For targets without boolean registers, this flag
114 /// returns information about the contents of the high-bits in the setcc
116 SetCCResultValue getSetCCResultContents() const { return SetCCResultContents;}
118 /// getSchedulingPreference - Return target scheduling preference.
119 SchedPreference getSchedulingPreference() const {
120 return SchedPreferenceInfo;
123 /// getRegClassFor - Return the register class that should be used for the
124 /// specified value type. This may only be called on legal types.
125 TargetRegisterClass *getRegClassFor(MVT::ValueType VT) const {
126 assert(!MVT::isExtendedVT(VT));
127 TargetRegisterClass *RC = RegClassForVT[VT];
128 assert(RC && "This value type is not natively supported!");
132 /// isTypeLegal - Return true if the target has native support for the
133 /// specified value type. This means that it has a register that directly
134 /// holds it without promotions or expansions.
135 bool isTypeLegal(MVT::ValueType VT) const {
136 return !MVT::isExtendedVT(VT) && RegClassForVT[VT] != 0;
139 class ValueTypeActionImpl {
140 /// ValueTypeActions - This is a bitvector that contains two bits for each
141 /// value type, where the two bits correspond to the LegalizeAction enum.
142 /// This can be queried with "getTypeAction(VT)".
143 uint32_t ValueTypeActions[2];
145 ValueTypeActionImpl() {
146 ValueTypeActions[0] = ValueTypeActions[1] = 0;
148 ValueTypeActionImpl(const ValueTypeActionImpl &RHS) {
149 ValueTypeActions[0] = RHS.ValueTypeActions[0];
150 ValueTypeActions[1] = RHS.ValueTypeActions[1];
153 LegalizeAction getTypeAction(MVT::ValueType VT) const {
154 if (MVT::isExtendedVT(VT)) {
155 if (MVT::isVector(VT)) return Expand;
156 if (MVT::isInteger(VT))
157 // First promote to a power-of-two size, then expand if necessary.
158 return VT == MVT::RoundIntegerType(VT) ? Expand : Promote;
159 assert(0 && "Unsupported extended type!");
161 return (LegalizeAction)((ValueTypeActions[VT>>4] >> ((2*VT) & 31)) & 3);
163 void setTypeAction(MVT::ValueType VT, LegalizeAction Action) {
164 assert(!MVT::isExtendedVT(VT));
165 assert(unsigned(VT >> 4) < array_lengthof(ValueTypeActions));
166 ValueTypeActions[VT>>4] |= Action << ((VT*2) & 31);
170 const ValueTypeActionImpl &getValueTypeActions() const {
171 return ValueTypeActions;
174 /// getTypeAction - Return how we should legalize values of this type, either
175 /// it is already legal (return 'Legal') or we need to promote it to a larger
176 /// type (return 'Promote'), or we need to expand it into multiple registers
177 /// of smaller integer type (return 'Expand'). 'Custom' is not an option.
178 LegalizeAction getTypeAction(MVT::ValueType VT) const {
179 return ValueTypeActions.getTypeAction(VT);
182 /// getTypeToTransformTo - For types supported by the target, this is an
183 /// identity function. For types that must be promoted to larger types, this
184 /// returns the larger type to promote to. For integer types that are larger
185 /// than the largest integer register, this contains one step in the expansion
186 /// to get to the smaller register. For illegal floating point types, this
187 /// returns the integer type to transform to.
188 MVT::ValueType getTypeToTransformTo(MVT::ValueType VT) const {
189 if (!MVT::isExtendedVT(VT)) {
190 MVT::ValueType NVT = TransformToType[VT];
191 assert(getTypeAction(NVT) != Promote &&
192 "Promote may not follow Expand or Promote");
196 if (MVT::isVector(VT))
197 return MVT::getVectorType(MVT::getVectorElementType(VT),
198 MVT::getVectorNumElements(VT) / 2);
199 if (MVT::isInteger(VT)) {
200 MVT::ValueType NVT = MVT::RoundIntegerType(VT);
202 // Size is a power of two - expand to half the size.
203 return MVT::getIntegerType(MVT::getSizeInBits(VT) / 2);
205 // Promote to a power of two size, avoiding multi-step promotion.
206 return getTypeAction(NVT) == Promote ? getTypeToTransformTo(NVT) : NVT;
208 assert(0 && "Unsupported extended type!");
211 /// getTypeToExpandTo - For types supported by the target, this is an
212 /// identity function. For types that must be expanded (i.e. integer types
213 /// that are larger than the largest integer register or illegal floating
214 /// point types), this returns the largest legal type it will be expanded to.
215 MVT::ValueType getTypeToExpandTo(MVT::ValueType VT) const {
216 assert(!MVT::isVector(VT));
218 switch (getTypeAction(VT)) {
222 VT = getTypeToTransformTo(VT);
225 assert(false && "Type is not legal nor is it to be expanded!");
232 /// getVectorTypeBreakdown - Vector types are broken down into some number of
233 /// legal first class types. For example, MVT::v8f32 maps to 2 MVT::v4f32
234 /// with Altivec or SSE1, or 8 promoted MVT::f64 values with the X86 FP stack.
235 /// Similarly, MVT::v2i64 turns into 4 MVT::i32 values with both PPC and X86.
237 /// This method returns the number of registers needed, and the VT for each
238 /// register. It also returns the VT and quantity of the intermediate values
239 /// before they are promoted/expanded.
241 unsigned getVectorTypeBreakdown(MVT::ValueType VT,
242 MVT::ValueType &IntermediateVT,
243 unsigned &NumIntermediates,
244 MVT::ValueType &RegisterVT) const;
246 typedef std::vector<APFloat>::const_iterator legal_fpimm_iterator;
247 legal_fpimm_iterator legal_fpimm_begin() const {
248 return LegalFPImmediates.begin();
250 legal_fpimm_iterator legal_fpimm_end() const {
251 return LegalFPImmediates.end();
254 /// isShuffleMaskLegal - Targets can use this to indicate that they only
255 /// support *some* VECTOR_SHUFFLE operations, those with specific masks.
256 /// By default, if a target supports the VECTOR_SHUFFLE node, all mask values
257 /// are assumed to be legal.
258 virtual bool isShuffleMaskLegal(SDOperand Mask, MVT::ValueType VT) const {
262 /// isVectorClearMaskLegal - Similar to isShuffleMaskLegal. This is
263 /// used by Targets can use this to indicate if there is a suitable
264 /// VECTOR_SHUFFLE that can be used to replace a VAND with a constant
266 virtual bool isVectorClearMaskLegal(std::vector<SDOperand> &BVOps,
268 SelectionDAG &DAG) const {
272 /// getOperationAction - Return how this operation should be treated: either
273 /// it is legal, needs to be promoted to a larger size, needs to be
274 /// expanded to some other code sequence, or the target has a custom expander
276 LegalizeAction getOperationAction(unsigned Op, MVT::ValueType VT) const {
277 if (MVT::isExtendedVT(VT)) return Expand;
278 return (LegalizeAction)((OpActions[Op] >> (2*VT)) & 3);
281 /// isOperationLegal - Return true if the specified operation is legal on this
283 bool isOperationLegal(unsigned Op, MVT::ValueType VT) const {
284 return getOperationAction(Op, VT) == Legal ||
285 getOperationAction(Op, VT) == Custom;
288 /// getLoadXAction - Return how this load with extension should be treated:
289 /// either it is legal, needs to be promoted to a larger size, needs to be
290 /// expanded to some other code sequence, or the target has a custom expander
292 LegalizeAction getLoadXAction(unsigned LType, MVT::ValueType VT) const {
293 if (MVT::isExtendedVT(VT)) return getTypeAction(VT);
294 return (LegalizeAction)((LoadXActions[LType] >> (2*VT)) & 3);
297 /// isLoadXLegal - Return true if the specified load with extension is legal
299 bool isLoadXLegal(unsigned LType, MVT::ValueType VT) const {
300 return getLoadXAction(LType, VT) == Legal ||
301 getLoadXAction(LType, VT) == Custom;
304 /// getTruncStoreAction - Return how this store with truncation should be
305 /// treated: either it is legal, needs to be promoted to a larger size, needs
306 /// to be expanded to some other code sequence, or the target has a custom
308 LegalizeAction getTruncStoreAction(MVT::ValueType ValVT,
309 MVT::ValueType MemVT) const {
310 assert(ValVT < MVT::LAST_VALUETYPE && MemVT < 32 &&
311 "Table isn't big enough!");
312 return (LegalizeAction)((TruncStoreActions[ValVT] >> (2*MemVT)) & 3);
315 /// isTruncStoreLegal - Return true if the specified store with truncation is
316 /// legal on this target.
317 bool isTruncStoreLegal(MVT::ValueType ValVT, MVT::ValueType MemVT) const {
318 return getTruncStoreAction(ValVT, MemVT) == Legal ||
319 getTruncStoreAction(ValVT, MemVT) == Custom;
322 /// getIndexedLoadAction - Return how the indexed load should be treated:
323 /// either it is legal, needs to be promoted to a larger size, needs to be
324 /// expanded to some other code sequence, or the target has a custom expander
327 getIndexedLoadAction(unsigned IdxMode, MVT::ValueType VT) const {
328 if (MVT::isExtendedVT(VT)) return getTypeAction(VT);
329 return (LegalizeAction)((IndexedModeActions[0][IdxMode] >> (2*VT)) & 3);
332 /// isIndexedLoadLegal - Return true if the specified indexed load is legal
334 bool isIndexedLoadLegal(unsigned IdxMode, MVT::ValueType VT) const {
335 return getIndexedLoadAction(IdxMode, VT) == Legal ||
336 getIndexedLoadAction(IdxMode, VT) == Custom;
339 /// getIndexedStoreAction - Return how the indexed store should be treated:
340 /// either it is legal, needs to be promoted to a larger size, needs to be
341 /// expanded to some other code sequence, or the target has a custom expander
344 getIndexedStoreAction(unsigned IdxMode, MVT::ValueType VT) const {
345 if (MVT::isExtendedVT(VT)) return getTypeAction(VT);
346 return (LegalizeAction)((IndexedModeActions[1][IdxMode] >> (2*VT)) & 3);
349 /// isIndexedStoreLegal - Return true if the specified indexed load is legal
351 bool isIndexedStoreLegal(unsigned IdxMode, MVT::ValueType VT) const {
352 return getIndexedStoreAction(IdxMode, VT) == Legal ||
353 getIndexedStoreAction(IdxMode, VT) == Custom;
356 /// getConvertAction - Return how the conversion should be treated:
357 /// either it is legal, needs to be promoted to a larger size, needs to be
358 /// expanded to some other code sequence, or the target has a custom expander
361 getConvertAction(MVT::ValueType FromVT, MVT::ValueType ToVT) const {
362 assert(FromVT < MVT::LAST_VALUETYPE && ToVT < 32 &&
363 "Table isn't big enough!");
364 return (LegalizeAction)((ConvertActions[FromVT] >> (2*ToVT)) & 3);
367 /// isConvertLegal - Return true if the specified conversion is legal
369 bool isConvertLegal(MVT::ValueType FromVT, MVT::ValueType ToVT) const {
370 return getConvertAction(FromVT, ToVT) == Legal ||
371 getConvertAction(FromVT, ToVT) == Custom;
374 /// getTypeToPromoteTo - If the action for this operation is to promote, this
375 /// method returns the ValueType to promote to.
376 MVT::ValueType getTypeToPromoteTo(unsigned Op, MVT::ValueType VT) const {
377 assert(getOperationAction(Op, VT) == Promote &&
378 "This operation isn't promoted!");
380 // See if this has an explicit type specified.
381 std::map<std::pair<unsigned, MVT::ValueType>,
382 MVT::ValueType>::const_iterator PTTI =
383 PromoteToType.find(std::make_pair(Op, VT));
384 if (PTTI != PromoteToType.end()) return PTTI->second;
386 assert((MVT::isInteger(VT) || MVT::isFloatingPoint(VT)) &&
387 "Cannot autopromote this type, add it with AddPromotedToType.");
389 MVT::ValueType NVT = VT;
391 NVT = (MVT::ValueType)(NVT+1);
392 assert(MVT::isInteger(NVT) == MVT::isInteger(VT) && NVT != MVT::isVoid &&
393 "Didn't find type to promote to!");
394 } while (!isTypeLegal(NVT) ||
395 getOperationAction(Op, NVT) == Promote);
399 /// getValueType - Return the MVT::ValueType corresponding to this LLVM type.
400 /// This is fixed by the LLVM operations except for the pointer size. If
401 /// AllowUnknown is true, this will return MVT::Other for types with no MVT
402 /// counterpart (e.g. structs), otherwise it will assert.
403 MVT::ValueType getValueType(const Type *Ty, bool AllowUnknown = false) const {
404 MVT::ValueType VT = MVT::getValueType(Ty, AllowUnknown);
405 return VT == MVT::iPTR ? PointerTy : VT;
408 /// getRegisterType - Return the type of registers that this ValueType will
409 /// eventually require.
410 MVT::ValueType getRegisterType(MVT::ValueType VT) const {
411 if (!MVT::isExtendedVT(VT))
412 return RegisterTypeForVT[VT];
413 if (MVT::isVector(VT)) {
414 MVT::ValueType VT1, RegisterVT;
415 unsigned NumIntermediates;
416 (void)getVectorTypeBreakdown(VT, VT1, NumIntermediates, RegisterVT);
419 assert(0 && "Unsupported extended type!");
422 /// getNumRegisters - Return the number of registers that this ValueType will
423 /// eventually require. This is one for any types promoted to live in larger
424 /// registers, but may be more than one for types (like i64) that are split
426 unsigned getNumRegisters(MVT::ValueType VT) const {
427 if (!MVT::isExtendedVT(VT))
428 return NumRegistersForVT[VT];
429 if (MVT::isVector(VT)) {
430 MVT::ValueType VT1, VT2;
431 unsigned NumIntermediates;
432 return getVectorTypeBreakdown(VT, VT1, NumIntermediates, VT2);
434 assert(0 && "Unsupported extended type!");
437 /// hasTargetDAGCombine - If true, the target has custom DAG combine
438 /// transformations that it can perform for the specified node.
439 bool hasTargetDAGCombine(ISD::NodeType NT) const {
440 return TargetDAGCombineArray[NT >> 3] & (1 << (NT&7));
443 /// This function returns the maximum number of store operations permitted
444 /// to replace a call to llvm.memset. The value is set by the target at the
445 /// performance threshold for such a replacement.
446 /// @brief Get maximum # of store operations permitted for llvm.memset
447 unsigned getMaxStoresPerMemset() const { return maxStoresPerMemset; }
449 /// This function returns the maximum number of store operations permitted
450 /// to replace a call to llvm.memcpy. The value is set by the target at the
451 /// performance threshold for such a replacement.
452 /// @brief Get maximum # of store operations permitted for llvm.memcpy
453 unsigned getMaxStoresPerMemcpy() const { return maxStoresPerMemcpy; }
455 /// This function returns the maximum number of store operations permitted
456 /// to replace a call to llvm.memmove. The value is set by the target at the
457 /// performance threshold for such a replacement.
458 /// @brief Get maximum # of store operations permitted for llvm.memmove
459 unsigned getMaxStoresPerMemmove() const { return maxStoresPerMemmove; }
461 /// This function returns true if the target allows unaligned memory accesses.
462 /// This is used, for example, in situations where an array copy/move/set is
463 /// converted to a sequence of store operations. It's use helps to ensure that
464 /// such replacements don't generate code that causes an alignment error
465 /// (trap) on the target machine.
466 /// @brief Determine if the target supports unaligned memory accesses.
467 bool allowsUnalignedMemoryAccesses() const {
468 return allowUnalignedMemoryAccesses;
471 /// usesUnderscoreSetJmp - Determine if we should use _setjmp or setjmp
472 /// to implement llvm.setjmp.
473 bool usesUnderscoreSetJmp() const {
474 return UseUnderscoreSetJmp;
477 /// usesUnderscoreLongJmp - Determine if we should use _longjmp or longjmp
478 /// to implement llvm.longjmp.
479 bool usesUnderscoreLongJmp() const {
480 return UseUnderscoreLongJmp;
483 /// getStackPointerRegisterToSaveRestore - If a physical register, this
484 /// specifies the register that llvm.savestack/llvm.restorestack should save
486 unsigned getStackPointerRegisterToSaveRestore() const {
487 return StackPointerRegisterToSaveRestore;
490 /// getExceptionAddressRegister - If a physical register, this returns
491 /// the register that receives the exception address on entry to a landing
493 unsigned getExceptionAddressRegister() const {
494 return ExceptionPointerRegister;
497 /// getExceptionSelectorRegister - If a physical register, this returns
498 /// the register that receives the exception typeid on entry to a landing
500 unsigned getExceptionSelectorRegister() const {
501 return ExceptionSelectorRegister;
504 /// getJumpBufSize - returns the target's jmp_buf size in bytes (if never
505 /// set, the default is 200)
506 unsigned getJumpBufSize() const {
510 /// getJumpBufAlignment - returns the target's jmp_buf alignment in bytes
511 /// (if never set, the default is 0)
512 unsigned getJumpBufAlignment() const {
513 return JumpBufAlignment;
516 /// getIfCvtBlockLimit - returns the target specific if-conversion block size
517 /// limit. Any block whose size is greater should not be predicated.
518 virtual unsigned getIfCvtBlockSizeLimit() const {
519 return IfCvtBlockSizeLimit;
522 /// getIfCvtDupBlockLimit - returns the target specific size limit for a
523 /// block to be considered for duplication. Any block whose size is greater
524 /// should not be duplicated to facilitate its predication.
525 virtual unsigned getIfCvtDupBlockSizeLimit() const {
526 return IfCvtDupBlockSizeLimit;
529 /// getPreIndexedAddressParts - returns true by value, base pointer and
530 /// offset pointer and addressing mode by reference if the node's address
531 /// can be legally represented as pre-indexed load / store address.
532 virtual bool getPreIndexedAddressParts(SDNode *N, SDOperand &Base,
534 ISD::MemIndexedMode &AM,
539 /// getPostIndexedAddressParts - returns true by value, base pointer and
540 /// offset pointer and addressing mode by reference if this node can be
541 /// combined with a load / store to form a post-indexed load / store.
542 virtual bool getPostIndexedAddressParts(SDNode *N, SDNode *Op,
543 SDOperand &Base, SDOperand &Offset,
544 ISD::MemIndexedMode &AM,
549 /// getPICJumpTableRelocaBase - Returns relocation base for the given PIC
551 virtual SDOperand getPICJumpTableRelocBase(SDOperand Table,
552 SelectionDAG &DAG) const;
554 //===--------------------------------------------------------------------===//
555 // TargetLowering Optimization Methods
558 /// TargetLoweringOpt - A convenience struct that encapsulates a DAG, and two
559 /// SDOperands for returning information from TargetLowering to its clients
560 /// that want to combine
561 struct TargetLoweringOpt {
567 explicit TargetLoweringOpt(SelectionDAG &InDAG, bool afterLegalize)
568 : DAG(InDAG), AfterLegalize(afterLegalize) {}
570 bool CombineTo(SDOperand O, SDOperand N) {
576 /// ShrinkDemandedConstant - Check to see if the specified operand of the
577 /// specified instruction is a constant integer. If so, check to see if
578 /// there are any bits set in the constant that are not demanded. If so,
579 /// shrink the constant and return true.
580 bool ShrinkDemandedConstant(SDOperand Op, uint64_t Demanded);
583 /// SimplifyDemandedBits - Look at Op. At this point, we know that only the
584 /// DemandedMask bits of the result of Op are ever used downstream. If we can
585 /// use this information to simplify Op, create a new simplified DAG node and
586 /// return true, returning the original and new nodes in Old and New.
587 /// Otherwise, analyze the expression and return a mask of KnownOne and
588 /// KnownZero bits for the expression (used to simplify the caller).
589 /// The KnownZero/One bits may only be accurate for those bits in the
591 bool SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
592 uint64_t &KnownZero, uint64_t &KnownOne,
593 TargetLoweringOpt &TLO, unsigned Depth = 0) const;
595 /// computeMaskedBitsForTargetNode - Determine which of the bits specified in
596 /// Mask are known to be either zero or one and return them in the
597 /// KnownZero/KnownOne bitsets.
598 virtual void computeMaskedBitsForTargetNode(const SDOperand Op,
602 const SelectionDAG &DAG,
603 unsigned Depth = 0) const;
605 /// ComputeNumSignBitsForTargetNode - This method can be implemented by
606 /// targets that want to expose additional information about sign bits to the
608 virtual unsigned ComputeNumSignBitsForTargetNode(SDOperand Op,
609 unsigned Depth = 0) const;
611 struct DAGCombinerInfo {
612 void *DC; // The DAG Combiner object.
614 bool CalledByLegalizer;
618 DAGCombinerInfo(SelectionDAG &dag, bool bl, bool cl, void *dc)
619 : DC(dc), BeforeLegalize(bl), CalledByLegalizer(cl), DAG(dag) {}
621 bool isBeforeLegalize() const { return BeforeLegalize; }
622 bool isCalledByLegalizer() const { return CalledByLegalizer; }
624 void AddToWorklist(SDNode *N);
625 SDOperand CombineTo(SDNode *N, const std::vector<SDOperand> &To);
626 SDOperand CombineTo(SDNode *N, SDOperand Res);
627 SDOperand CombineTo(SDNode *N, SDOperand Res0, SDOperand Res1);
630 /// SimplifySetCC - Try to simplify a setcc built with the specified operands
631 /// and cc. If it is unable to simplify it, return a null SDOperand.
632 SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N0, SDOperand N1,
633 ISD::CondCode Cond, bool foldBooleans,
634 DAGCombinerInfo &DCI) const;
636 /// PerformDAGCombine - This method will be invoked for all target nodes and
637 /// for any target-independent nodes that the target has registered with
640 /// The semantics are as follows:
642 /// SDOperand.Val == 0 - No change was made
643 /// SDOperand.Val == N - N was replaced, is dead, and is already handled.
644 /// otherwise - N should be replaced by the returned Operand.
646 /// In addition, methods provided by DAGCombinerInfo may be used to perform
647 /// more complex transformations.
649 virtual SDOperand PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
651 //===--------------------------------------------------------------------===//
652 // TargetLowering Configuration Methods - These methods should be invoked by
653 // the derived class constructor to configure this object for the target.
657 /// setUsesGlobalOffsetTable - Specify that this target does or doesn't use a
658 /// GOT for PC-relative code.
659 void setUsesGlobalOffsetTable(bool V) { UsesGlobalOffsetTable = V; }
661 /// setShiftAmountType - Describe the type that should be used for shift
662 /// amounts. This type defaults to the pointer type.
663 void setShiftAmountType(MVT::ValueType VT) { ShiftAmountTy = VT; }
665 /// setSetCCResultType - Describe the type that shoudl be used as the result
666 /// of a setcc operation. This defaults to the pointer type.
667 void setSetCCResultType(MVT::ValueType VT) { SetCCResultTy = VT; }
669 /// setSetCCResultContents - Specify how the target extends the result of a
670 /// setcc operation in a register.
671 void setSetCCResultContents(SetCCResultValue Ty) { SetCCResultContents = Ty; }
673 /// setSchedulingPreference - Specify the target scheduling preference.
674 void setSchedulingPreference(SchedPreference Pref) {
675 SchedPreferenceInfo = Pref;
678 /// setShiftAmountFlavor - Describe how the target handles out of range shift
680 void setShiftAmountFlavor(OutOfRangeShiftAmount OORSA) {
681 ShiftAmtHandling = OORSA;
684 /// setUseUnderscoreSetJmp - Indicate whether this target prefers to
685 /// use _setjmp to implement llvm.setjmp or the non _ version.
686 /// Defaults to false.
687 void setUseUnderscoreSetJmp(bool Val) {
688 UseUnderscoreSetJmp = Val;
691 /// setUseUnderscoreLongJmp - Indicate whether this target prefers to
692 /// use _longjmp to implement llvm.longjmp or the non _ version.
693 /// Defaults to false.
694 void setUseUnderscoreLongJmp(bool Val) {
695 UseUnderscoreLongJmp = Val;
698 /// setStackPointerRegisterToSaveRestore - If set to a physical register, this
699 /// specifies the register that llvm.savestack/llvm.restorestack should save
701 void setStackPointerRegisterToSaveRestore(unsigned R) {
702 StackPointerRegisterToSaveRestore = R;
705 /// setExceptionPointerRegister - If set to a physical register, this sets
706 /// the register that receives the exception address on entry to a landing
708 void setExceptionPointerRegister(unsigned R) {
709 ExceptionPointerRegister = R;
712 /// setExceptionSelectorRegister - If set to a physical register, this sets
713 /// the register that receives the exception typeid on entry to a landing
715 void setExceptionSelectorRegister(unsigned R) {
716 ExceptionSelectorRegister = R;
719 /// SelectIsExpensive - Tells the code generator not to expand operations
720 /// into sequences that use the select operations if possible.
721 void setSelectIsExpensive() { SelectIsExpensive = true; }
723 /// setIntDivIsCheap - Tells the code generator that integer divide is
724 /// expensive, and if possible, should be replaced by an alternate sequence
725 /// of instructions not containing an integer divide.
726 void setIntDivIsCheap(bool isCheap = true) { IntDivIsCheap = isCheap; }
728 /// setPow2DivIsCheap - Tells the code generator that it shouldn't generate
729 /// srl/add/sra for a signed divide by power of two, and let the target handle
731 void setPow2DivIsCheap(bool isCheap = true) { Pow2DivIsCheap = isCheap; }
733 /// addRegisterClass - Add the specified register class as an available
734 /// regclass for the specified value type. This indicates the selector can
735 /// handle values of that class natively.
736 void addRegisterClass(MVT::ValueType VT, TargetRegisterClass *RC) {
737 assert(!MVT::isExtendedVT(VT));
738 AvailableRegClasses.push_back(std::make_pair(VT, RC));
739 RegClassForVT[VT] = RC;
742 /// computeRegisterProperties - Once all of the register classes are added,
743 /// this allows us to compute derived properties we expose.
744 void computeRegisterProperties();
746 /// setOperationAction - Indicate that the specified operation does not work
747 /// with the specified type and indicate what to do about it.
748 void setOperationAction(unsigned Op, MVT::ValueType VT,
749 LegalizeAction Action) {
750 assert(VT < 32 && Op < array_lengthof(OpActions) &&
751 "Table isn't big enough!");
752 OpActions[Op] &= ~(uint64_t(3UL) << VT*2);
753 OpActions[Op] |= (uint64_t)Action << VT*2;
756 /// setLoadXAction - Indicate that the specified load with extension does not
757 /// work with the with specified type and indicate what to do about it.
758 void setLoadXAction(unsigned ExtType, MVT::ValueType VT,
759 LegalizeAction Action) {
760 assert(VT < 32 && ExtType < array_lengthof(LoadXActions) &&
761 "Table isn't big enough!");
762 LoadXActions[ExtType] &= ~(uint64_t(3UL) << VT*2);
763 LoadXActions[ExtType] |= (uint64_t)Action << VT*2;
766 /// setTruncStoreAction - Indicate that the specified truncating store does
767 /// not work with the with specified type and indicate what to do about it.
768 void setTruncStoreAction(MVT::ValueType ValVT, MVT::ValueType MemVT,
769 LegalizeAction Action) {
770 assert(ValVT < MVT::LAST_VALUETYPE && MemVT < 32 &&
771 "Table isn't big enough!");
772 TruncStoreActions[ValVT] &= ~(uint64_t(3UL) << MemVT*2);
773 TruncStoreActions[ValVT] |= (uint64_t)Action << MemVT*2;
776 /// setIndexedLoadAction - Indicate that the specified indexed load does or
777 /// does not work with the with specified type and indicate what to do abort
778 /// it. NOTE: All indexed mode loads are initialized to Expand in
779 /// TargetLowering.cpp
780 void setIndexedLoadAction(unsigned IdxMode, MVT::ValueType VT,
781 LegalizeAction Action) {
782 assert(VT < 32 && IdxMode <
783 array_lengthof(IndexedModeActions[0]) &&
784 "Table isn't big enough!");
785 IndexedModeActions[0][IdxMode] &= ~(uint64_t(3UL) << VT*2);
786 IndexedModeActions[0][IdxMode] |= (uint64_t)Action << VT*2;
789 /// setIndexedStoreAction - Indicate that the specified indexed store does or
790 /// does not work with the with specified type and indicate what to do about
791 /// it. NOTE: All indexed mode stores are initialized to Expand in
792 /// TargetLowering.cpp
793 void setIndexedStoreAction(unsigned IdxMode, MVT::ValueType VT,
794 LegalizeAction Action) {
795 assert(VT < 32 && IdxMode <
796 array_lengthof(IndexedModeActions[1]) &&
797 "Table isn't big enough!");
798 IndexedModeActions[1][IdxMode] &= ~(uint64_t(3UL) << VT*2);
799 IndexedModeActions[1][IdxMode] |= (uint64_t)Action << VT*2;
802 /// setConvertAction - Indicate that the specified conversion does or does
803 /// not work with the with specified type and indicate what to do about it.
804 void setConvertAction(MVT::ValueType FromVT, MVT::ValueType ToVT,
805 LegalizeAction Action) {
806 assert(FromVT < MVT::LAST_VALUETYPE && ToVT < 32 &&
807 "Table isn't big enough!");
808 ConvertActions[FromVT] &= ~(uint64_t(3UL) << ToVT*2);
809 ConvertActions[FromVT] |= (uint64_t)Action << ToVT*2;
812 /// AddPromotedToType - If Opc/OrigVT is specified as being promoted, the
813 /// promotion code defaults to trying a larger integer/fp until it can find
814 /// one that works. If that default is insufficient, this method can be used
815 /// by the target to override the default.
816 void AddPromotedToType(unsigned Opc, MVT::ValueType OrigVT,
817 MVT::ValueType DestVT) {
818 PromoteToType[std::make_pair(Opc, OrigVT)] = DestVT;
821 /// addLegalFPImmediate - Indicate that this target can instruction select
822 /// the specified FP immediate natively.
823 void addLegalFPImmediate(const APFloat& Imm) {
824 LegalFPImmediates.push_back(Imm);
827 /// setTargetDAGCombine - Targets should invoke this method for each target
828 /// independent node that they want to provide a custom DAG combiner for by
829 /// implementing the PerformDAGCombine virtual method.
830 void setTargetDAGCombine(ISD::NodeType NT) {
831 TargetDAGCombineArray[NT >> 3] |= 1 << (NT&7);
834 /// setJumpBufSize - Set the target's required jmp_buf buffer size (in
835 /// bytes); default is 200
836 void setJumpBufSize(unsigned Size) {
840 /// setJumpBufAlignment - Set the target's required jmp_buf buffer
841 /// alignment (in bytes); default is 0
842 void setJumpBufAlignment(unsigned Align) {
843 JumpBufAlignment = Align;
846 /// setIfCvtBlockSizeLimit - Set the target's if-conversion block size
847 /// limit (in number of instructions); default is 2.
848 void setIfCvtBlockSizeLimit(unsigned Limit) {
849 IfCvtBlockSizeLimit = Limit;
852 /// setIfCvtDupBlockSizeLimit - Set the target's block size limit (in number
853 /// of instructions) to be considered for code duplication during
854 /// if-conversion; default is 2.
855 void setIfCvtDupBlockSizeLimit(unsigned Limit) {
856 IfCvtDupBlockSizeLimit = Limit;
861 virtual const TargetSubtarget *getSubtarget() {
862 assert(0 && "Not Implemented");
863 return NULL; // this is here to silence compiler errors
865 //===--------------------------------------------------------------------===//
866 // Lowering methods - These methods must be implemented by targets so that
867 // the SelectionDAGLowering code knows how to lower these.
870 /// LowerArguments - This hook must be implemented to indicate how we should
871 /// lower the arguments for the specified function, into the specified DAG.
872 virtual std::vector<SDOperand>
873 LowerArguments(Function &F, SelectionDAG &DAG);
875 /// LowerCallTo - This hook lowers an abstract call to a function into an
876 /// actual call. This returns a pair of operands. The first element is the
877 /// return value for the function (if RetTy is not VoidTy). The second
878 /// element is the outgoing token chain.
879 struct ArgListEntry {
889 ArgListEntry() : isSExt(false), isZExt(false), isInReg(false),
890 isSRet(false), isNest(false), isByVal(false) { }
892 typedef std::vector<ArgListEntry> ArgListTy;
893 virtual std::pair<SDOperand, SDOperand>
894 LowerCallTo(SDOperand Chain, const Type *RetTy, bool RetTyIsSigned,
895 bool isVarArg, unsigned CallingConv, bool isTailCall,
896 SDOperand Callee, ArgListTy &Args, SelectionDAG &DAG);
899 virtual SDOperand LowerMEMCPY(SDOperand Op, SelectionDAG &DAG);
900 virtual SDOperand LowerMEMCPYCall(SDOperand Chain, SDOperand Dest,
901 SDOperand Source, SDOperand Count,
903 virtual SDOperand LowerMEMCPYInline(SDOperand Chain, SDOperand Dest,
904 SDOperand Source, unsigned Size,
905 unsigned Align, SelectionDAG &DAG) {
906 assert(0 && "Not Implemented");
907 return SDOperand(); // this is here to silence compiler errors
911 /// LowerOperation - This callback is invoked for operations that are
912 /// unsupported by the target, which are registered to use 'custom' lowering,
913 /// and whose defined values are all legal.
914 /// If the target has no operations that require custom lowering, it need not
915 /// implement this. The default implementation of this aborts.
916 virtual SDOperand LowerOperation(SDOperand Op, SelectionDAG &DAG);
918 /// ExpandOperationResult - This callback is invoked for operations that are
919 /// unsupported by the target, which are registered to use 'custom' lowering,
920 /// and whose result type needs to be expanded. This must return a node whose
921 /// results precisely match the results of the input node. This typically
922 /// involves a MERGE_VALUES node and/or BUILD_PAIR.
924 /// If the target has no operations that require custom lowering, it need not
925 /// implement this. The default implementation of this aborts.
926 virtual SDNode *ExpandOperationResult(SDNode *N, SelectionDAG &DAG) {
927 assert(0 && "ExpandOperationResult not implemented for this target!");
931 /// IsEligibleForTailCallOptimization - Check whether the call is eligible for
932 /// tail call optimization. Targets which want to do tail call optimization
933 /// should override this function.
934 virtual bool IsEligibleForTailCallOptimization(SDOperand Call,
936 SelectionDAG &DAG) const {
940 /// CustomPromoteOperation - This callback is invoked for operations that are
941 /// unsupported by the target, are registered to use 'custom' lowering, and
942 /// whose type needs to be promoted.
943 virtual SDOperand CustomPromoteOperation(SDOperand Op, SelectionDAG &DAG);
945 /// getTargetNodeName() - This method returns the name of a target specific
947 virtual const char *getTargetNodeName(unsigned Opcode) const;
949 //===--------------------------------------------------------------------===//
950 // Inline Asm Support hooks
953 enum ConstraintType {
954 C_Register, // Constraint represents a single register.
955 C_RegisterClass, // Constraint represents one or more registers.
956 C_Memory, // Memory constraint.
957 C_Other, // Something else.
958 C_Unknown // Unsupported constraint.
961 /// getConstraintType - Given a constraint, return the type of constraint it
962 /// is for this target.
963 virtual ConstraintType getConstraintType(const std::string &Constraint) const;
966 /// getRegClassForInlineAsmConstraint - Given a constraint letter (e.g. "r"),
967 /// return a list of registers that can be used to satisfy the constraint.
968 /// This should only be used for C_RegisterClass constraints.
969 virtual std::vector<unsigned>
970 getRegClassForInlineAsmConstraint(const std::string &Constraint,
971 MVT::ValueType VT) const;
973 /// getRegForInlineAsmConstraint - Given a physical register constraint (e.g.
974 /// {edx}), return the register number and the register class for the
977 /// Given a register class constraint, like 'r', if this corresponds directly
978 /// to an LLVM register class, return a register of 0 and the register class
981 /// This should only be used for C_Register constraints. On error,
982 /// this returns a register number of 0 and a null register class pointer..
983 virtual std::pair<unsigned, const TargetRegisterClass*>
984 getRegForInlineAsmConstraint(const std::string &Constraint,
985 MVT::ValueType VT) const;
988 /// LowerAsmOperandForConstraint - Lower the specified operand into the Ops
989 /// vector. If it is invalid, don't add anything to Ops.
990 virtual void LowerAsmOperandForConstraint(SDOperand Op, char ConstraintLetter,
991 std::vector<SDOperand> &Ops,
994 //===--------------------------------------------------------------------===//
998 // InsertAtEndOfBasicBlock - This method should be implemented by targets that
999 // mark instructions with the 'usesCustomDAGSchedInserter' flag. These
1000 // instructions are special in various ways, which require special support to
1001 // insert. The specified MachineInstr is created but not inserted into any
1002 // basic blocks, and the scheduler passes ownership of it to this method.
1003 virtual MachineBasicBlock *InsertAtEndOfBasicBlock(MachineInstr *MI,
1004 MachineBasicBlock *MBB);
1006 //===--------------------------------------------------------------------===//
1007 // Addressing mode description hooks (used by LSR etc).
1010 /// AddrMode - This represents an addressing mode of:
1011 /// BaseGV + BaseOffs + BaseReg + Scale*ScaleReg
1012 /// If BaseGV is null, there is no BaseGV.
1013 /// If BaseOffs is zero, there is no base offset.
1014 /// If HasBaseReg is false, there is no base register.
1015 /// If Scale is zero, there is no ScaleReg. Scale of 1 indicates a reg with
1019 GlobalValue *BaseGV;
1023 AddrMode() : BaseGV(0), BaseOffs(0), HasBaseReg(false), Scale(0) {}
1026 /// isLegalAddressingMode - Return true if the addressing mode represented by
1027 /// AM is legal for this target, for a load/store of the specified type.
1028 /// TODO: Handle pre/postinc as well.
1029 virtual bool isLegalAddressingMode(const AddrMode &AM, const Type *Ty) const;
1031 /// isTruncateFree - Return true if it's free to truncate a value of
1032 /// type Ty1 to type Ty2. e.g. On x86 it's free to truncate a i32 value in
1033 /// register EAX to i16 by referencing its sub-register AX.
1034 virtual bool isTruncateFree(const Type *Ty1, const Type *Ty2) const {
1038 virtual bool isTruncateFree(MVT::ValueType VT1, MVT::ValueType VT2) const {
1042 //===--------------------------------------------------------------------===//
1043 // Div utility functions
1045 SDOperand BuildSDIV(SDNode *N, SelectionDAG &DAG,
1046 std::vector<SDNode*>* Created) const;
1047 SDOperand BuildUDIV(SDNode *N, SelectionDAG &DAG,
1048 std::vector<SDNode*>* Created) const;
1051 //===--------------------------------------------------------------------===//
1052 // Runtime Library hooks
1055 /// setLibcallName - Rename the default libcall routine name for the specified
1057 void setLibcallName(RTLIB::Libcall Call, const char *Name) {
1058 LibcallRoutineNames[Call] = Name;
1061 /// getLibcallName - Get the libcall routine name for the specified libcall.
1063 const char *getLibcallName(RTLIB::Libcall Call) const {
1064 return LibcallRoutineNames[Call];
1067 /// setCmpLibcallCC - Override the default CondCode to be used to test the
1068 /// result of the comparison libcall against zero.
1069 void setCmpLibcallCC(RTLIB::Libcall Call, ISD::CondCode CC) {
1070 CmpLibcallCCs[Call] = CC;
1073 /// getCmpLibcallCC - Get the CondCode that's to be used to test the result of
1074 /// the comparison libcall against zero.
1075 ISD::CondCode getCmpLibcallCC(RTLIB::Libcall Call) const {
1076 return CmpLibcallCCs[Call];
1081 const TargetData *TD;
1083 /// IsLittleEndian - True if this is a little endian target.
1085 bool IsLittleEndian;
1087 /// PointerTy - The type to use for pointers, usually i32 or i64.
1089 MVT::ValueType PointerTy;
1091 /// UsesGlobalOffsetTable - True if this target uses a GOT for PIC codegen.
1093 bool UsesGlobalOffsetTable;
1095 /// ShiftAmountTy - The type to use for shift amounts, usually i8 or whatever
1097 MVT::ValueType ShiftAmountTy;
1099 OutOfRangeShiftAmount ShiftAmtHandling;
1101 /// SelectIsExpensive - Tells the code generator not to expand operations
1102 /// into sequences that use the select operations if possible.
1103 bool SelectIsExpensive;
1105 /// IntDivIsCheap - Tells the code generator not to expand integer divides by
1106 /// constants into a sequence of muls, adds, and shifts. This is a hack until
1107 /// a real cost model is in place. If we ever optimize for size, this will be
1108 /// set to true unconditionally.
1111 /// Pow2DivIsCheap - Tells the code generator that it shouldn't generate
1112 /// srl/add/sra for a signed divide by power of two, and let the target handle
1114 bool Pow2DivIsCheap;
1116 /// SetCCResultTy - The type that SetCC operations use. This defaults to the
1118 MVT::ValueType SetCCResultTy;
1120 /// SetCCResultContents - Information about the contents of the high-bits in
1121 /// the result of a setcc comparison operation.
1122 SetCCResultValue SetCCResultContents;
1124 /// SchedPreferenceInfo - The target scheduling preference: shortest possible
1125 /// total cycles or lowest register usage.
1126 SchedPreference SchedPreferenceInfo;
1128 /// UseUnderscoreSetJmp - This target prefers to use _setjmp to implement
1129 /// llvm.setjmp. Defaults to false.
1130 bool UseUnderscoreSetJmp;
1132 /// UseUnderscoreLongJmp - This target prefers to use _longjmp to implement
1133 /// llvm.longjmp. Defaults to false.
1134 bool UseUnderscoreLongJmp;
1136 /// JumpBufSize - The size, in bytes, of the target's jmp_buf buffers
1137 unsigned JumpBufSize;
1139 /// JumpBufAlignment - The alignment, in bytes, of the target's jmp_buf
1141 unsigned JumpBufAlignment;
1143 /// IfCvtBlockSizeLimit - The maximum allowed size for a block to be
1145 unsigned IfCvtBlockSizeLimit;
1147 /// IfCvtDupBlockSizeLimit - The maximum allowed size for a block to be
1148 /// duplicated during if-conversion.
1149 unsigned IfCvtDupBlockSizeLimit;
1151 /// StackPointerRegisterToSaveRestore - If set to a physical register, this
1152 /// specifies the register that llvm.savestack/llvm.restorestack should save
1154 unsigned StackPointerRegisterToSaveRestore;
1156 /// ExceptionPointerRegister - If set to a physical register, this specifies
1157 /// the register that receives the exception address on entry to a landing
1159 unsigned ExceptionPointerRegister;
1161 /// ExceptionSelectorRegister - If set to a physical register, this specifies
1162 /// the register that receives the exception typeid on entry to a landing
1164 unsigned ExceptionSelectorRegister;
1166 /// RegClassForVT - This indicates the default register class to use for
1167 /// each ValueType the target supports natively.
1168 TargetRegisterClass *RegClassForVT[MVT::LAST_VALUETYPE];
1169 unsigned char NumRegistersForVT[MVT::LAST_VALUETYPE];
1170 MVT::ValueType RegisterTypeForVT[MVT::LAST_VALUETYPE];
1172 /// TransformToType - For any value types we are promoting or expanding, this
1173 /// contains the value type that we are changing to. For Expanded types, this
1174 /// contains one step of the expand (e.g. i64 -> i32), even if there are
1175 /// multiple steps required (e.g. i64 -> i16). For types natively supported
1176 /// by the system, this holds the same type (e.g. i32 -> i32).
1177 MVT::ValueType TransformToType[MVT::LAST_VALUETYPE];
1179 /// OpActions - For each operation and each value type, keep a LegalizeAction
1180 /// that indicates how instruction selection should deal with the operation.
1181 /// Most operations are Legal (aka, supported natively by the target), but
1182 /// operations that are not should be described. Note that operations on
1183 /// non-legal value types are not described here.
1184 uint64_t OpActions[156];
1186 /// LoadXActions - For each load of load extension type and each value type,
1187 /// keep a LegalizeAction that indicates how instruction selection should deal
1189 uint64_t LoadXActions[ISD::LAST_LOADX_TYPE];
1191 /// TruncStoreActions - For each truncating store, keep a LegalizeAction that
1192 /// indicates how instruction selection should deal with the store.
1193 uint64_t TruncStoreActions[MVT::LAST_VALUETYPE];
1195 /// IndexedModeActions - For each indexed mode and each value type, keep a
1196 /// pair of LegalizeAction that indicates how instruction selection should
1197 /// deal with the load / store.
1198 uint64_t IndexedModeActions[2][ISD::LAST_INDEXED_MODE];
1200 /// ConvertActions - For each conversion from source type to destination type,
1201 /// keep a LegalizeAction that indicates how instruction selection should
1202 /// deal with the conversion.
1203 /// Currently, this is used only for floating->floating conversions
1204 /// (FP_EXTEND and FP_ROUND).
1205 uint64_t ConvertActions[MVT::LAST_VALUETYPE];
1207 ValueTypeActionImpl ValueTypeActions;
1209 std::vector<APFloat> LegalFPImmediates;
1211 std::vector<std::pair<MVT::ValueType,
1212 TargetRegisterClass*> > AvailableRegClasses;
1214 /// TargetDAGCombineArray - Targets can specify ISD nodes that they would
1215 /// like PerformDAGCombine callbacks for by calling setTargetDAGCombine(),
1216 /// which sets a bit in this array.
1217 unsigned char TargetDAGCombineArray[156/(sizeof(unsigned char)*8)];
1219 /// PromoteToType - For operations that must be promoted to a specific type,
1220 /// this holds the destination type. This map should be sparse, so don't hold
1223 /// Targets add entries to this map with AddPromotedToType(..), clients access
1224 /// this with getTypeToPromoteTo(..).
1225 std::map<std::pair<unsigned, MVT::ValueType>, MVT::ValueType> PromoteToType;
1227 /// LibcallRoutineNames - Stores the name each libcall.
1229 const char *LibcallRoutineNames[RTLIB::UNKNOWN_LIBCALL];
1231 /// CmpLibcallCCs - The ISD::CondCode that should be used to test the result
1232 /// of each of the comparison libcall against zero.
1233 ISD::CondCode CmpLibcallCCs[RTLIB::UNKNOWN_LIBCALL];
1236 /// When lowering %llvm.memset this field specifies the maximum number of
1237 /// store operations that may be substituted for the call to memset. Targets
1238 /// must set this value based on the cost threshold for that target. Targets
1239 /// should assume that the memset will be done using as many of the largest
1240 /// store operations first, followed by smaller ones, if necessary, per
1241 /// alignment restrictions. For example, storing 9 bytes on a 32-bit machine
1242 /// with 16-bit alignment would result in four 2-byte stores and one 1-byte
1243 /// store. This only applies to setting a constant array of a constant size.
1244 /// @brief Specify maximum number of store instructions per memset call.
1245 unsigned maxStoresPerMemset;
1247 /// When lowering %llvm.memcpy this field specifies the maximum number of
1248 /// store operations that may be substituted for a call to memcpy. Targets
1249 /// must set this value based on the cost threshold for that target. Targets
1250 /// should assume that the memcpy will be done using as many of the largest
1251 /// store operations first, followed by smaller ones, if necessary, per
1252 /// alignment restrictions. For example, storing 7 bytes on a 32-bit machine
1253 /// with 32-bit alignment would result in one 4-byte store, a one 2-byte store
1254 /// and one 1-byte store. This only applies to copying a constant array of
1256 /// @brief Specify maximum bytes of store instructions per memcpy call.
1257 unsigned maxStoresPerMemcpy;
1259 /// When lowering %llvm.memmove this field specifies the maximum number of
1260 /// store instructions that may be substituted for a call to memmove. Targets
1261 /// must set this value based on the cost threshold for that target. Targets
1262 /// should assume that the memmove will be done using as many of the largest
1263 /// store operations first, followed by smaller ones, if necessary, per
1264 /// alignment restrictions. For example, moving 9 bytes on a 32-bit machine
1265 /// with 8-bit alignment would result in nine 1-byte stores. This only
1266 /// applies to copying a constant array of constant size.
1267 /// @brief Specify maximum bytes of store instructions per memmove call.
1268 unsigned maxStoresPerMemmove;
1270 /// This field specifies whether the target machine permits unaligned memory
1271 /// accesses. This is used, for example, to determine the size of store
1272 /// operations when copying small arrays and other similar tasks.
1273 /// @brief Indicate whether the target permits unaligned memory accesses.
1274 bool allowUnalignedMemoryAccesses;
1276 } // end llvm namespace