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 //===----------------------------------------------------------------------===//
11 /// This file describes how to lower LLVM code to machine code. This has two
14 /// 1. Which ValueTypes are natively supported by the target.
15 /// 2. Which operations are supported for supported ValueTypes.
16 /// 3. Cost thresholds for alternative implementations of certain operations.
18 /// In addition it has a few other components, like information about FP
21 //===----------------------------------------------------------------------===//
23 #ifndef LLVM_TARGET_TARGETLOWERING_H
24 #define LLVM_TARGET_TARGETLOWERING_H
26 #include "llvm/ADT/DenseMap.h"
27 #include "llvm/CodeGen/DAGCombine.h"
28 #include "llvm/CodeGen/RuntimeLibcalls.h"
29 #include "llvm/CodeGen/SelectionDAGNodes.h"
30 #include "llvm/IR/Attributes.h"
31 #include "llvm/IR/CallSite.h"
32 #include "llvm/IR/CallingConv.h"
33 #include "llvm/IR/InlineAsm.h"
34 #include "llvm/IR/Instructions.h"
35 #include "llvm/IR/IRBuilder.h"
36 #include "llvm/MC/MCRegisterInfo.h"
37 #include "llvm/Target/TargetCallingConv.h"
38 #include "llvm/Target/TargetMachine.h"
47 class FunctionLoweringInfo;
48 class ImmutableCallSite;
50 class MachineBasicBlock;
51 class MachineFunction;
53 class MachineJumpTableInfo;
59 template<typename T> class SmallVectorImpl;
61 class TargetRegisterClass;
62 class TargetLibraryInfo;
63 class TargetLoweringObjectFile;
68 None, // No preference
69 Source, // Follow source order.
70 RegPressure, // Scheduling for lowest register pressure.
71 Hybrid, // Scheduling for both latency and register pressure.
72 ILP, // Scheduling for ILP in low register pressure mode.
73 VLIW // Scheduling for VLIW targets.
77 /// This base class for TargetLowering contains the SelectionDAG-independent
78 /// parts that can be used from the rest of CodeGen.
79 class TargetLoweringBase {
80 TargetLoweringBase(const TargetLoweringBase&) LLVM_DELETED_FUNCTION;
81 void operator=(const TargetLoweringBase&) LLVM_DELETED_FUNCTION;
84 /// This enum indicates whether operations are valid for a target, and if not,
85 /// what action should be used to make them valid.
87 Legal, // The target natively supports this operation.
88 Promote, // This operation should be executed in a larger type.
89 Expand, // Try to expand this to other ops, otherwise use a libcall.
90 Custom // Use the LowerOperation hook to implement custom lowering.
93 /// This enum indicates whether a types are legal for a target, and if not,
94 /// what action should be used to make them valid.
95 enum LegalizeTypeAction {
96 TypeLegal, // The target natively supports this type.
97 TypePromoteInteger, // Replace this integer with a larger one.
98 TypeExpandInteger, // Split this integer into two of half the size.
99 TypeSoftenFloat, // Convert this float to a same size integer type.
100 TypeExpandFloat, // Split this float into two of half the size.
101 TypeScalarizeVector, // Replace this one-element vector with its element.
102 TypeSplitVector, // Split this vector into two of half the size.
103 TypeWidenVector // This vector should be widened into a larger vector.
106 /// LegalizeKind holds the legalization kind that needs to happen to EVT
107 /// in order to type-legalize it.
108 typedef std::pair<LegalizeTypeAction, EVT> LegalizeKind;
110 /// Enum that describes how the target represents true/false values.
111 enum BooleanContent {
112 UndefinedBooleanContent, // Only bit 0 counts, the rest can hold garbage.
113 ZeroOrOneBooleanContent, // All bits zero except for bit 0.
114 ZeroOrNegativeOneBooleanContent // All bits equal to bit 0.
117 /// Enum that describes what type of support for selects the target has.
118 enum SelectSupportKind {
119 ScalarValSelect, // The target supports scalar selects (ex: cmov).
120 ScalarCondVectorVal, // The target supports selects with a scalar condition
121 // and vector values (ex: cmov).
122 VectorMaskSelect // The target supports vector selects with a vector
123 // mask (ex: x86 blends).
126 static ISD::NodeType getExtendForContent(BooleanContent Content) {
128 case UndefinedBooleanContent:
129 // Extend by adding rubbish bits.
130 return ISD::ANY_EXTEND;
131 case ZeroOrOneBooleanContent:
132 // Extend by adding zero bits.
133 return ISD::ZERO_EXTEND;
134 case ZeroOrNegativeOneBooleanContent:
135 // Extend by copying the sign bit.
136 return ISD::SIGN_EXTEND;
138 llvm_unreachable("Invalid content kind");
141 /// NOTE: The TargetMachine owns TLOF.
142 explicit TargetLoweringBase(const TargetMachine &TM);
143 virtual ~TargetLoweringBase() {}
146 /// \brief Initialize all of the actions to default values.
150 const TargetMachine &getTargetMachine() const { return TM; }
151 const DataLayout *getDataLayout() const { return DL; }
152 const TargetLoweringObjectFile &getObjFileLowering() const {
153 return *TM.getObjFileLowering();
156 bool isBigEndian() const { return !IsLittleEndian; }
157 bool isLittleEndian() const { return IsLittleEndian; }
159 /// Return the pointer type for the given address space, defaults to
160 /// the pointer type from the data layout.
161 /// FIXME: The default needs to be removed once all the code is updated.
162 virtual MVT getPointerTy(uint32_t /*AS*/ = 0) const;
163 unsigned getPointerSizeInBits(uint32_t AS = 0) const;
164 unsigned getPointerTypeSizeInBits(Type *Ty) const;
165 virtual MVT getScalarShiftAmountTy(EVT LHSTy) const;
167 EVT getShiftAmountTy(EVT LHSTy) const;
169 /// Returns the type to be used for the index operand of:
170 /// ISD::INSERT_VECTOR_ELT, ISD::EXTRACT_VECTOR_ELT,
171 /// ISD::INSERT_SUBVECTOR, and ISD::EXTRACT_SUBVECTOR
172 virtual MVT getVectorIdxTy() const {
173 return getPointerTy();
176 /// Return true if the select operation is expensive for this target.
177 bool isSelectExpensive() const { return SelectIsExpensive; }
179 virtual bool isSelectSupported(SelectSupportKind /*kind*/) const {
183 /// Return true if multiple condition registers are available.
184 bool hasMultipleConditionRegisters() const {
185 return HasMultipleConditionRegisters;
188 /// Return true if the target has BitExtract instructions.
189 bool hasExtractBitsInsn() const { return HasExtractBitsInsn; }
191 /// Return the preferred vector type legalization action.
192 virtual TargetLoweringBase::LegalizeTypeAction
193 getPreferredVectorAction(EVT VT) const {
194 // The default action for one element vectors is to scalarize
195 if (VT.getVectorNumElements() == 1)
196 return TypeScalarizeVector;
197 // The default action for other vectors is to promote
198 return TypePromoteInteger;
201 // There are two general methods for expanding a BUILD_VECTOR node:
202 // 1. Use SCALAR_TO_VECTOR on the defined scalar values and then shuffle
204 // 2. Build the vector on the stack and then load it.
205 // If this function returns true, then method (1) will be used, subject to
206 // the constraint that all of the necessary shuffles are legal (as determined
207 // by isShuffleMaskLegal). If this function returns false, then method (2) is
208 // always used. The vector type, and the number of defined values, are
211 shouldExpandBuildVectorWithShuffles(EVT /* VT */,
212 unsigned DefinedValues) const {
213 return DefinedValues < 3;
216 /// Return true if integer divide is usually cheaper than a sequence of
217 /// several shifts, adds, and multiplies for this target.
218 bool isIntDivCheap() const { return IntDivIsCheap; }
220 /// Returns true if target has indicated at least one type should be bypassed.
221 bool isSlowDivBypassed() const { return !BypassSlowDivWidths.empty(); }
223 /// Returns map of slow types for division or remainder with corresponding
225 const DenseMap<unsigned int, unsigned int> &getBypassSlowDivWidths() const {
226 return BypassSlowDivWidths;
229 /// Return true if pow2 sdiv is cheaper than a chain of sra/srl/add/sra.
230 bool isPow2SDivCheap() const { return Pow2SDivIsCheap; }
232 /// Return true if Flow Control is an expensive operation that should be
234 bool isJumpExpensive() const { return JumpIsExpensive; }
236 /// Return true if selects are only cheaper than branches if the branch is
237 /// unlikely to be predicted right.
238 bool isPredictableSelectExpensive() const {
239 return PredictableSelectIsExpensive;
242 /// isLoadBitCastBeneficial() - Return true if the following transform
244 /// fold (conv (load x)) -> (load (conv*)x)
245 /// On architectures that don't natively support some vector loads efficiently,
246 /// casting the load to a smaller vector of larger types and loading
247 /// is more efficient, however, this can be undone by optimizations in
249 virtual bool isLoadBitCastBeneficial(EVT /* Load */, EVT /* Bitcast */) const {
253 /// \brief Return true if it is cheap to speculate a call to intrinsic cttz.
254 virtual bool isCheapToSpeculateCttz() const {
258 /// \brief Return true if it is cheap to speculate a call to intrinsic ctlz.
259 virtual bool isCheapToSpeculateCtlz() const {
263 /// \brief Return if the target supports combining a
266 /// %andResult = and %val1, #imm-with-one-bit-set;
267 /// %icmpResult = icmp %andResult, 0
268 /// br i1 %icmpResult, label %dest1, label %dest2
270 /// into a single machine instruction of a form like:
272 /// brOnBitSet %register, #bitNumber, dest
274 bool isMaskAndBranchFoldingLegal() const {
275 return MaskAndBranchFoldingIsLegal;
278 /// \brief Return true if the target wants to use the optimization that
279 /// turns ext(promotableInst1(...(promotableInstN(load)))) into
280 /// promotedInst1(...(promotedInstN(ext(load)))).
281 bool enableExtLdPromotion() const { return EnableExtLdPromotion; }
283 /// Return true if the target can combine store(extractelement VectorTy,
285 /// \p Cost[out] gives the cost of that transformation when this is true.
286 virtual bool canCombineStoreAndExtract(Type *VectorTy, Value *Idx,
287 unsigned &Cost) const {
291 /// Return true if target supports floating point exceptions.
292 bool hasFloatingPointExceptions() const {
293 return HasFloatingPointExceptions;
296 /// Return true if target always beneficiates from combining into FMA for a
297 /// given value type. This must typically return false on targets where FMA
298 /// takes more cycles to execute than FADD.
299 virtual bool enableAggressiveFMAFusion(EVT VT) const {
303 /// Return the ValueType of the result of SETCC operations.
304 virtual EVT getSetCCResultType(LLVMContext &Context, EVT VT) const;
306 /// Return the ValueType for comparison libcalls. Comparions libcalls include
307 /// floating point comparion calls, and Ordered/Unordered check calls on
308 /// floating point numbers.
310 MVT::SimpleValueType getCmpLibcallReturnType() const;
312 /// For targets without i1 registers, this gives the nature of the high-bits
313 /// of boolean values held in types wider than i1.
315 /// "Boolean values" are special true/false values produced by nodes like
316 /// SETCC and consumed (as the condition) by nodes like SELECT and BRCOND.
317 /// Not to be confused with general values promoted from i1. Some cpus
318 /// distinguish between vectors of boolean and scalars; the isVec parameter
319 /// selects between the two kinds. For example on X86 a scalar boolean should
320 /// be zero extended from i1, while the elements of a vector of booleans
321 /// should be sign extended from i1.
323 /// Some cpus also treat floating point types the same way as they treat
324 /// vectors instead of the way they treat scalars.
325 BooleanContent getBooleanContents(bool isVec, bool isFloat) const {
327 return BooleanVectorContents;
328 return isFloat ? BooleanFloatContents : BooleanContents;
331 BooleanContent getBooleanContents(EVT Type) const {
332 return getBooleanContents(Type.isVector(), Type.isFloatingPoint());
335 /// Return target scheduling preference.
336 Sched::Preference getSchedulingPreference() const {
337 return SchedPreferenceInfo;
340 /// Some scheduler, e.g. hybrid, can switch to different scheduling heuristics
341 /// for different nodes. This function returns the preference (or none) for
343 virtual Sched::Preference getSchedulingPreference(SDNode *) const {
347 /// Return the register class that should be used for the specified value
349 virtual const TargetRegisterClass *getRegClassFor(MVT VT) const {
350 const TargetRegisterClass *RC = RegClassForVT[VT.SimpleTy];
351 assert(RC && "This value type is not natively supported!");
355 /// Return the 'representative' register class for the specified value
358 /// The 'representative' register class is the largest legal super-reg
359 /// register class for the register class of the value type. For example, on
360 /// i386 the rep register class for i8, i16, and i32 are GR32; while the rep
361 /// register class is GR64 on x86_64.
362 virtual const TargetRegisterClass *getRepRegClassFor(MVT VT) const {
363 const TargetRegisterClass *RC = RepRegClassForVT[VT.SimpleTy];
367 /// Return the cost of the 'representative' register class for the specified
369 virtual uint8_t getRepRegClassCostFor(MVT VT) const {
370 return RepRegClassCostForVT[VT.SimpleTy];
373 /// Return true if the target has native support for the specified value type.
374 /// This means that it has a register that directly holds it without
375 /// promotions or expansions.
376 bool isTypeLegal(EVT VT) const {
377 assert(!VT.isSimple() ||
378 (unsigned)VT.getSimpleVT().SimpleTy < array_lengthof(RegClassForVT));
379 return VT.isSimple() && RegClassForVT[VT.getSimpleVT().SimpleTy] != nullptr;
382 class ValueTypeActionImpl {
383 /// ValueTypeActions - For each value type, keep a LegalizeTypeAction enum
384 /// that indicates how instruction selection should deal with the type.
385 uint8_t ValueTypeActions[MVT::LAST_VALUETYPE];
388 ValueTypeActionImpl() {
389 std::fill(std::begin(ValueTypeActions), std::end(ValueTypeActions), 0);
392 LegalizeTypeAction getTypeAction(MVT VT) const {
393 return (LegalizeTypeAction)ValueTypeActions[VT.SimpleTy];
396 void setTypeAction(MVT VT, LegalizeTypeAction Action) {
397 unsigned I = VT.SimpleTy;
398 ValueTypeActions[I] = Action;
402 const ValueTypeActionImpl &getValueTypeActions() const {
403 return ValueTypeActions;
406 /// Return how we should legalize values of this type, either it is already
407 /// legal (return 'Legal') or we need to promote it to a larger type (return
408 /// 'Promote'), or we need to expand it into multiple registers of smaller
409 /// integer type (return 'Expand'). 'Custom' is not an option.
410 LegalizeTypeAction getTypeAction(LLVMContext &Context, EVT VT) const {
411 return getTypeConversion(Context, VT).first;
413 LegalizeTypeAction getTypeAction(MVT VT) const {
414 return ValueTypeActions.getTypeAction(VT);
417 /// For types supported by the target, this is an identity function. For
418 /// types that must be promoted to larger types, this returns the larger type
419 /// to promote to. For integer types that are larger than the largest integer
420 /// register, this contains one step in the expansion to get to the smaller
421 /// register. For illegal floating point types, this returns the integer type
423 EVT getTypeToTransformTo(LLVMContext &Context, EVT VT) const {
424 return getTypeConversion(Context, VT).second;
427 /// For types supported by the target, this is an identity function. For
428 /// types that must be expanded (i.e. integer types that are larger than the
429 /// largest integer register or illegal floating point types), this returns
430 /// the largest legal type it will be expanded to.
431 EVT getTypeToExpandTo(LLVMContext &Context, EVT VT) const {
432 assert(!VT.isVector());
434 switch (getTypeAction(Context, VT)) {
437 case TypeExpandInteger:
438 VT = getTypeToTransformTo(Context, VT);
441 llvm_unreachable("Type is not legal nor is it to be expanded!");
446 /// Vector types are broken down into some number of legal first class types.
447 /// For example, EVT::v8f32 maps to 2 EVT::v4f32 with Altivec or SSE1, or 8
448 /// promoted EVT::f64 values with the X86 FP stack. Similarly, EVT::v2i64
449 /// turns into 4 EVT::i32 values with both PPC and X86.
451 /// This method returns the number of registers needed, and the VT for each
452 /// register. It also returns the VT and quantity of the intermediate values
453 /// before they are promoted/expanded.
454 unsigned getVectorTypeBreakdown(LLVMContext &Context, EVT VT,
456 unsigned &NumIntermediates,
457 MVT &RegisterVT) const;
459 struct IntrinsicInfo {
460 unsigned opc; // target opcode
461 EVT memVT; // memory VT
462 const Value* ptrVal; // value representing memory location
463 int offset; // offset off of ptrVal
464 unsigned size; // the size of the memory location
465 // (taken from memVT if zero)
466 unsigned align; // alignment
467 bool vol; // is volatile?
468 bool readMem; // reads memory?
469 bool writeMem; // writes memory?
471 IntrinsicInfo() : opc(0), ptrVal(nullptr), offset(0), size(0), align(1),
472 vol(false), readMem(false), writeMem(false) {}
475 /// Given an intrinsic, checks if on the target the intrinsic will need to map
476 /// to a MemIntrinsicNode (touches memory). If this is the case, it returns
477 /// true and store the intrinsic information into the IntrinsicInfo that was
478 /// passed to the function.
479 virtual bool getTgtMemIntrinsic(IntrinsicInfo &, const CallInst &,
480 unsigned /*Intrinsic*/) const {
484 /// Returns true if the target can instruction select the specified FP
485 /// immediate natively. If false, the legalizer will materialize the FP
486 /// immediate as a load from a constant pool.
487 virtual bool isFPImmLegal(const APFloat &/*Imm*/, EVT /*VT*/) const {
491 /// Targets can use this to indicate that they only support *some*
492 /// VECTOR_SHUFFLE operations, those with specific masks. By default, if a
493 /// target supports the VECTOR_SHUFFLE node, all mask values are assumed to be
495 virtual bool isShuffleMaskLegal(const SmallVectorImpl<int> &/*Mask*/,
500 /// Returns true if the operation can trap for the value type.
502 /// VT must be a legal type. By default, we optimistically assume most
503 /// operations don't trap except for divide and remainder.
504 virtual bool canOpTrap(unsigned Op, EVT VT) const;
506 /// Similar to isShuffleMaskLegal. This is used by Targets can use this to
507 /// indicate if there is a suitable VECTOR_SHUFFLE that can be used to replace
508 /// a VAND with a constant pool entry.
509 virtual bool isVectorClearMaskLegal(const SmallVectorImpl<int> &/*Mask*/,
514 /// Return how this operation should be treated: either it is legal, needs to
515 /// be promoted to a larger size, needs to be expanded to some other code
516 /// sequence, or the target has a custom expander for it.
517 LegalizeAction getOperationAction(unsigned Op, EVT VT) const {
518 if (VT.isExtended()) return Expand;
519 // If a target-specific SDNode requires legalization, require the target
520 // to provide custom legalization for it.
521 if (Op > array_lengthof(OpActions[0])) return Custom;
522 unsigned I = (unsigned) VT.getSimpleVT().SimpleTy;
523 return (LegalizeAction)OpActions[I][Op];
526 /// Return true if the specified operation is legal on this target or can be
527 /// made legal with custom lowering. This is used to help guide high-level
528 /// lowering decisions.
529 bool isOperationLegalOrCustom(unsigned Op, EVT VT) const {
530 return (VT == MVT::Other || isTypeLegal(VT)) &&
531 (getOperationAction(Op, VT) == Legal ||
532 getOperationAction(Op, VT) == Custom);
535 /// Return true if the specified operation is legal on this target or can be
536 /// made legal using promotion. This is used to help guide high-level lowering
538 bool isOperationLegalOrPromote(unsigned Op, EVT VT) const {
539 return (VT == MVT::Other || isTypeLegal(VT)) &&
540 (getOperationAction(Op, VT) == Legal ||
541 getOperationAction(Op, VT) == Promote);
544 /// Return true if the specified operation is illegal on this target or
545 /// unlikely to be made legal with custom lowering. This is used to help guide
546 /// high-level lowering decisions.
547 bool isOperationExpand(unsigned Op, EVT VT) const {
548 return (!isTypeLegal(VT) || getOperationAction(Op, VT) == Expand);
551 /// Return true if the specified operation is legal on this target.
552 bool isOperationLegal(unsigned Op, EVT VT) const {
553 return (VT == MVT::Other || isTypeLegal(VT)) &&
554 getOperationAction(Op, VT) == Legal;
557 /// Return how this load with extension should be treated: either it is legal,
558 /// needs to be promoted to a larger size, needs to be expanded to some other
559 /// code sequence, or the target has a custom expander for it.
560 LegalizeAction getLoadExtAction(unsigned ExtType, EVT VT) const {
561 if (VT.isExtended()) return Expand;
562 unsigned I = (unsigned) VT.getSimpleVT().SimpleTy;
563 assert(ExtType < ISD::LAST_LOADEXT_TYPE && I < MVT::LAST_VALUETYPE &&
564 "Table isn't big enough!");
565 return (LegalizeAction)LoadExtActions[I][ExtType];
568 /// Return true if the specified load with extension is legal on this target.
569 bool isLoadExtLegal(unsigned ExtType, EVT VT) const {
570 return VT.isSimple() &&
571 getLoadExtAction(ExtType, VT.getSimpleVT()) == Legal;
574 /// Return how this store with truncation should be treated: either it is
575 /// legal, needs to be promoted to a larger size, needs to be expanded to some
576 /// other code sequence, or the target has a custom expander for it.
577 LegalizeAction getTruncStoreAction(EVT ValVT, EVT MemVT) const {
578 if (ValVT.isExtended() || MemVT.isExtended()) return Expand;
579 unsigned ValI = (unsigned) ValVT.getSimpleVT().SimpleTy;
580 unsigned MemI = (unsigned) MemVT.getSimpleVT().SimpleTy;
581 assert(ValI < MVT::LAST_VALUETYPE && MemI < MVT::LAST_VALUETYPE &&
582 "Table isn't big enough!");
583 return (LegalizeAction)TruncStoreActions[ValI][MemI];
586 /// Return true if the specified store with truncation is legal on this
588 bool isTruncStoreLegal(EVT ValVT, EVT MemVT) const {
589 return isTypeLegal(ValVT) && MemVT.isSimple() &&
590 getTruncStoreAction(ValVT.getSimpleVT(), MemVT.getSimpleVT()) == Legal;
593 /// Return how the indexed load should be treated: either it is legal, needs
594 /// to be promoted to a larger size, needs to be expanded to some other code
595 /// sequence, or the target has a custom expander for it.
597 getIndexedLoadAction(unsigned IdxMode, MVT VT) const {
598 assert(IdxMode < ISD::LAST_INDEXED_MODE && VT.isValid() &&
599 "Table isn't big enough!");
600 unsigned Ty = (unsigned)VT.SimpleTy;
601 return (LegalizeAction)((IndexedModeActions[Ty][IdxMode] & 0xf0) >> 4);
604 /// Return true if the specified indexed load is legal on this target.
605 bool isIndexedLoadLegal(unsigned IdxMode, EVT VT) const {
606 return VT.isSimple() &&
607 (getIndexedLoadAction(IdxMode, VT.getSimpleVT()) == Legal ||
608 getIndexedLoadAction(IdxMode, VT.getSimpleVT()) == Custom);
611 /// Return how the indexed store should be treated: either it is legal, needs
612 /// to be promoted to a larger size, needs to be expanded to some other code
613 /// sequence, or the target has a custom expander for it.
615 getIndexedStoreAction(unsigned IdxMode, MVT VT) const {
616 assert(IdxMode < ISD::LAST_INDEXED_MODE && VT.isValid() &&
617 "Table isn't big enough!");
618 unsigned Ty = (unsigned)VT.SimpleTy;
619 return (LegalizeAction)(IndexedModeActions[Ty][IdxMode] & 0x0f);
622 /// Return true if the specified indexed load is legal on this target.
623 bool isIndexedStoreLegal(unsigned IdxMode, EVT VT) const {
624 return VT.isSimple() &&
625 (getIndexedStoreAction(IdxMode, VT.getSimpleVT()) == Legal ||
626 getIndexedStoreAction(IdxMode, VT.getSimpleVT()) == Custom);
629 /// Return how the condition code should be treated: either it is legal, needs
630 /// to be expanded to some other code sequence, or the target has a custom
633 getCondCodeAction(ISD::CondCode CC, MVT VT) const {
634 assert((unsigned)CC < array_lengthof(CondCodeActions) &&
635 ((unsigned)VT.SimpleTy >> 4) < array_lengthof(CondCodeActions[0]) &&
636 "Table isn't big enough!");
637 // See setCondCodeAction for how this is encoded.
638 uint32_t Shift = 2 * (VT.SimpleTy & 0xF);
639 uint32_t Value = CondCodeActions[CC][VT.SimpleTy >> 4];
640 LegalizeAction Action = (LegalizeAction) ((Value >> Shift) & 0x3);
641 assert(Action != Promote && "Can't promote condition code!");
645 /// Return true if the specified condition code is legal on this target.
646 bool isCondCodeLegal(ISD::CondCode CC, MVT VT) const {
648 getCondCodeAction(CC, VT) == Legal ||
649 getCondCodeAction(CC, VT) == Custom;
653 /// If the action for this operation is to promote, this method returns the
654 /// ValueType to promote to.
655 MVT getTypeToPromoteTo(unsigned Op, MVT VT) const {
656 assert(getOperationAction(Op, VT) == Promote &&
657 "This operation isn't promoted!");
659 // See if this has an explicit type specified.
660 std::map<std::pair<unsigned, MVT::SimpleValueType>,
661 MVT::SimpleValueType>::const_iterator PTTI =
662 PromoteToType.find(std::make_pair(Op, VT.SimpleTy));
663 if (PTTI != PromoteToType.end()) return PTTI->second;
665 assert((VT.isInteger() || VT.isFloatingPoint()) &&
666 "Cannot autopromote this type, add it with AddPromotedToType.");
670 NVT = (MVT::SimpleValueType)(NVT.SimpleTy+1);
671 assert(NVT.isInteger() == VT.isInteger() && NVT != MVT::isVoid &&
672 "Didn't find type to promote to!");
673 } while (!isTypeLegal(NVT) ||
674 getOperationAction(Op, NVT) == Promote);
678 /// Return the EVT corresponding to this LLVM type. This is fixed by the LLVM
679 /// operations except for the pointer size. If AllowUnknown is true, this
680 /// will return MVT::Other for types with no EVT counterpart (e.g. structs),
681 /// otherwise it will assert.
682 EVT getValueType(Type *Ty, bool AllowUnknown = false) const {
683 // Lower scalar pointers to native pointer types.
684 if (PointerType *PTy = dyn_cast<PointerType>(Ty))
685 return getPointerTy(PTy->getAddressSpace());
687 if (Ty->isVectorTy()) {
688 VectorType *VTy = cast<VectorType>(Ty);
689 Type *Elm = VTy->getElementType();
690 // Lower vectors of pointers to native pointer types.
691 if (PointerType *PT = dyn_cast<PointerType>(Elm)) {
692 EVT PointerTy(getPointerTy(PT->getAddressSpace()));
693 Elm = PointerTy.getTypeForEVT(Ty->getContext());
696 return EVT::getVectorVT(Ty->getContext(), EVT::getEVT(Elm, false),
697 VTy->getNumElements());
699 return EVT::getEVT(Ty, AllowUnknown);
702 /// Return the MVT corresponding to this LLVM type. See getValueType.
703 MVT getSimpleValueType(Type *Ty, bool AllowUnknown = false) const {
704 return getValueType(Ty, AllowUnknown).getSimpleVT();
707 /// Return the desired alignment for ByVal or InAlloca aggregate function
708 /// arguments in the caller parameter area. This is the actual alignment, not
710 virtual unsigned getByValTypeAlignment(Type *Ty) const;
712 /// Return the type of registers that this ValueType will eventually require.
713 MVT getRegisterType(MVT VT) const {
714 assert((unsigned)VT.SimpleTy < array_lengthof(RegisterTypeForVT));
715 return RegisterTypeForVT[VT.SimpleTy];
718 /// Return the type of registers that this ValueType will eventually require.
719 MVT getRegisterType(LLVMContext &Context, EVT VT) const {
721 assert((unsigned)VT.getSimpleVT().SimpleTy <
722 array_lengthof(RegisterTypeForVT));
723 return RegisterTypeForVT[VT.getSimpleVT().SimpleTy];
728 unsigned NumIntermediates;
729 (void)getVectorTypeBreakdown(Context, VT, VT1,
730 NumIntermediates, RegisterVT);
733 if (VT.isInteger()) {
734 return getRegisterType(Context, getTypeToTransformTo(Context, VT));
736 llvm_unreachable("Unsupported extended type!");
739 /// Return the number of registers that this ValueType will eventually
742 /// This is one for any types promoted to live in larger registers, but may be
743 /// more than one for types (like i64) that are split into pieces. For types
744 /// like i140, which are first promoted then expanded, it is the number of
745 /// registers needed to hold all the bits of the original type. For an i140
746 /// on a 32 bit machine this means 5 registers.
747 unsigned getNumRegisters(LLVMContext &Context, EVT VT) const {
749 assert((unsigned)VT.getSimpleVT().SimpleTy <
750 array_lengthof(NumRegistersForVT));
751 return NumRegistersForVT[VT.getSimpleVT().SimpleTy];
756 unsigned NumIntermediates;
757 return getVectorTypeBreakdown(Context, VT, VT1, NumIntermediates, VT2);
759 if (VT.isInteger()) {
760 unsigned BitWidth = VT.getSizeInBits();
761 unsigned RegWidth = getRegisterType(Context, VT).getSizeInBits();
762 return (BitWidth + RegWidth - 1) / RegWidth;
764 llvm_unreachable("Unsupported extended type!");
767 /// If true, then instruction selection should seek to shrink the FP constant
768 /// of the specified type to a smaller type in order to save space and / or
770 virtual bool ShouldShrinkFPConstant(EVT) const { return true; }
772 // Return true if it is profitable to reduce the given load node to a smaller
775 // e.g. (i16 (trunc (i32 (load x))) -> i16 load x should be performed
776 virtual bool shouldReduceLoadWidth(SDNode *Load,
777 ISD::LoadExtType ExtTy,
782 /// When splitting a value of the specified type into parts, does the Lo
783 /// or Hi part come first? This usually follows the endianness, except
784 /// for ppcf128, where the Hi part always comes first.
785 bool hasBigEndianPartOrdering(EVT VT) const {
786 return isBigEndian() || VT == MVT::ppcf128;
789 /// If true, the target has custom DAG combine transformations that it can
790 /// perform for the specified node.
791 bool hasTargetDAGCombine(ISD::NodeType NT) const {
792 assert(unsigned(NT >> 3) < array_lengthof(TargetDAGCombineArray));
793 return TargetDAGCombineArray[NT >> 3] & (1 << (NT&7));
796 /// \brief Get maximum # of store operations permitted for llvm.memset
798 /// This function returns the maximum number of store operations permitted
799 /// to replace a call to llvm.memset. The value is set by the target at the
800 /// performance threshold for such a replacement. If OptSize is true,
801 /// return the limit for functions that have OptSize attribute.
802 unsigned getMaxStoresPerMemset(bool OptSize) const {
803 return OptSize ? MaxStoresPerMemsetOptSize : MaxStoresPerMemset;
806 /// \brief Get maximum # of store operations permitted for llvm.memcpy
808 /// This function returns the maximum number of store operations permitted
809 /// to replace a call to llvm.memcpy. The value is set by the target at the
810 /// performance threshold for such a replacement. If OptSize is true,
811 /// return the limit for functions that have OptSize attribute.
812 unsigned getMaxStoresPerMemcpy(bool OptSize) const {
813 return OptSize ? MaxStoresPerMemcpyOptSize : MaxStoresPerMemcpy;
816 /// \brief Get maximum # of store operations permitted for llvm.memmove
818 /// This function returns the maximum number of store operations permitted
819 /// to replace a call to llvm.memmove. The value is set by the target at the
820 /// performance threshold for such a replacement. If OptSize is true,
821 /// return the limit for functions that have OptSize attribute.
822 unsigned getMaxStoresPerMemmove(bool OptSize) const {
823 return OptSize ? MaxStoresPerMemmoveOptSize : MaxStoresPerMemmove;
826 /// \brief Determine if the target supports unaligned memory accesses.
828 /// This function returns true if the target allows unaligned memory accesses
829 /// of the specified type in the given address space. If true, it also returns
830 /// whether the unaligned memory access is "fast" in the last argument by
831 /// reference. This is used, for example, in situations where an array
832 /// copy/move/set is converted to a sequence of store operations. Its use
833 /// helps to ensure that such replacements don't generate code that causes an
834 /// alignment error (trap) on the target machine.
835 virtual bool allowsMisalignedMemoryAccesses(EVT,
836 unsigned AddrSpace = 0,
838 bool * /*Fast*/ = nullptr) const {
842 /// Returns the target specific optimal type for load and store operations as
843 /// a result of memset, memcpy, and memmove lowering.
845 /// If DstAlign is zero that means it's safe to destination alignment can
846 /// satisfy any constraint. Similarly if SrcAlign is zero it means there isn't
847 /// a need to check it against alignment requirement, probably because the
848 /// source does not need to be loaded. If 'IsMemset' is true, that means it's
849 /// expanding a memset. If 'ZeroMemset' is true, that means it's a memset of
850 /// zero. 'MemcpyStrSrc' indicates whether the memcpy source is constant so it
851 /// does not need to be loaded. It returns EVT::Other if the type should be
852 /// determined using generic target-independent logic.
853 virtual EVT getOptimalMemOpType(uint64_t /*Size*/,
854 unsigned /*DstAlign*/, unsigned /*SrcAlign*/,
857 bool /*MemcpyStrSrc*/,
858 MachineFunction &/*MF*/) const {
862 /// Returns true if it's safe to use load / store of the specified type to
863 /// expand memcpy / memset inline.
865 /// This is mostly true for all types except for some special cases. For
866 /// example, on X86 targets without SSE2 f64 load / store are done with fldl /
867 /// fstpl which also does type conversion. Note the specified type doesn't
868 /// have to be legal as the hook is used before type legalization.
869 virtual bool isSafeMemOpType(MVT /*VT*/) const { return true; }
871 /// Determine if we should use _setjmp or setjmp to implement llvm.setjmp.
872 bool usesUnderscoreSetJmp() const {
873 return UseUnderscoreSetJmp;
876 /// Determine if we should use _longjmp or longjmp to implement llvm.longjmp.
877 bool usesUnderscoreLongJmp() const {
878 return UseUnderscoreLongJmp;
881 /// Return integer threshold on number of blocks to use jump tables rather
882 /// than if sequence.
883 int getMinimumJumpTableEntries() const {
884 return MinimumJumpTableEntries;
887 /// If a physical register, this specifies the register that
888 /// llvm.savestack/llvm.restorestack should save and restore.
889 unsigned getStackPointerRegisterToSaveRestore() const {
890 return StackPointerRegisterToSaveRestore;
893 /// If a physical register, this returns the register that receives the
894 /// exception address on entry to a landing pad.
895 unsigned getExceptionPointerRegister() const {
896 return ExceptionPointerRegister;
899 /// If a physical register, this returns the register that receives the
900 /// exception typeid on entry to a landing pad.
901 unsigned getExceptionSelectorRegister() const {
902 return ExceptionSelectorRegister;
905 /// Returns the target's jmp_buf size in bytes (if never set, the default is
907 unsigned getJumpBufSize() const {
911 /// Returns the target's jmp_buf alignment in bytes (if never set, the default
913 unsigned getJumpBufAlignment() const {
914 return JumpBufAlignment;
917 /// Return the minimum stack alignment of an argument.
918 unsigned getMinStackArgumentAlignment() const {
919 return MinStackArgumentAlignment;
922 /// Return the minimum function alignment.
923 unsigned getMinFunctionAlignment() const {
924 return MinFunctionAlignment;
927 /// Return the preferred function alignment.
928 unsigned getPrefFunctionAlignment() const {
929 return PrefFunctionAlignment;
932 /// Return the preferred loop alignment.
933 virtual unsigned getPrefLoopAlignment(MachineLoop *ML = nullptr) const {
934 return PrefLoopAlignment;
937 /// Return whether the DAG builder should automatically insert fences and
938 /// reduce ordering for atomics.
939 bool getInsertFencesForAtomic() const {
940 return InsertFencesForAtomic;
943 /// Return true if the target stores stack protector cookies at a fixed offset
944 /// in some non-standard address space, and populates the address space and
945 /// offset as appropriate.
946 virtual bool getStackCookieLocation(unsigned &/*AddressSpace*/,
947 unsigned &/*Offset*/) const {
951 /// Returns the maximal possible offset which can be used for loads / stores
953 virtual unsigned getMaximalGlobalOffset() const {
957 /// Returns true if a cast between SrcAS and DestAS is a noop.
958 virtual bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const {
962 //===--------------------------------------------------------------------===//
963 /// \name Helpers for TargetTransformInfo implementations
966 /// Get the ISD node that corresponds to the Instruction class opcode.
967 int InstructionOpcodeToISD(unsigned Opcode) const;
969 /// Estimate the cost of type-legalization and the legalized type.
970 std::pair<unsigned, MVT> getTypeLegalizationCost(Type *Ty) const;
974 //===--------------------------------------------------------------------===//
975 /// \name Helpers for atomic expansion.
978 /// True if AtomicExpandPass should use emitLoadLinked/emitStoreConditional
979 /// and expand AtomicCmpXchgInst.
980 virtual bool hasLoadLinkedStoreConditional() const { return false; }
982 /// Perform a load-linked operation on Addr, returning a "Value *" with the
983 /// corresponding pointee type. This may entail some non-trivial operations to
984 /// truncate or reconstruct types that will be illegal in the backend. See
985 /// ARMISelLowering for an example implementation.
986 virtual Value *emitLoadLinked(IRBuilder<> &Builder, Value *Addr,
987 AtomicOrdering Ord) const {
988 llvm_unreachable("Load linked unimplemented on this target");
991 /// Perform a store-conditional operation to Addr. Return the status of the
992 /// store. This should be 0 if the store succeeded, non-zero otherwise.
993 virtual Value *emitStoreConditional(IRBuilder<> &Builder, Value *Val,
994 Value *Addr, AtomicOrdering Ord) const {
995 llvm_unreachable("Store conditional unimplemented on this target");
998 /// Inserts in the IR a target-specific intrinsic specifying a fence.
999 /// It is called by AtomicExpandPass before expanding an
1000 /// AtomicRMW/AtomicCmpXchg/AtomicStore/AtomicLoad.
1001 /// RMW and CmpXchg set both IsStore and IsLoad to true.
1002 /// This function should either return a nullptr, or a pointer to an IR-level
1003 /// Instruction*. Even complex fence sequences can be represented by a
1004 /// single Instruction* through an intrinsic to be lowered later.
1005 /// Backends with !getInsertFencesForAtomic() should keep a no-op here.
1006 /// Backends should override this method to produce target-specific intrinsic
1007 /// for their fences.
1008 /// FIXME: Please note that the default implementation here in terms of
1009 /// IR-level fences exists for historical/compatibility reasons and is
1010 /// *unsound* ! Fences cannot, in general, be used to restore sequential
1011 /// consistency. For example, consider the following example:
1012 /// atomic<int> x = y = 0;
1013 /// int r1, r2, r3, r4;
1024 /// r1 = r3 = 1 and r2 = r4 = 0 is impossible as long as the accesses are all
1025 /// seq_cst. But if they are lowered to monotonic accesses, no amount of
1026 /// IR-level fences can prevent it.
1028 virtual Instruction* emitLeadingFence(IRBuilder<> &Builder, AtomicOrdering Ord,
1029 bool IsStore, bool IsLoad) const {
1030 if (!getInsertFencesForAtomic())
1033 if (isAtLeastRelease(Ord) && IsStore)
1034 return Builder.CreateFence(Ord);
1039 virtual Instruction* emitTrailingFence(IRBuilder<> &Builder, AtomicOrdering Ord,
1040 bool IsStore, bool IsLoad) const {
1041 if (!getInsertFencesForAtomic())
1044 if (isAtLeastAcquire(Ord))
1045 return Builder.CreateFence(Ord);
1051 /// Returns true if the given (atomic) store should be expanded by the
1052 /// IR-level AtomicExpand pass into an "atomic xchg" which ignores its input.
1053 virtual bool shouldExpandAtomicStoreInIR(StoreInst *SI) const {
1057 /// Returns true if the given (atomic) load should be expanded by the
1058 /// IR-level AtomicExpand pass into a load-linked instruction
1059 /// (through emitLoadLinked()).
1060 virtual bool shouldExpandAtomicLoadInIR(LoadInst *LI) const { return false; }
1062 /// Returns true if the given AtomicRMW should be expanded by the
1063 /// IR-level AtomicExpand pass into a loop using LoadLinked/StoreConditional.
1064 virtual bool shouldExpandAtomicRMWInIR(AtomicRMWInst *RMWI) const {
1068 /// On some platforms, an AtomicRMW that never actually modifies the value
1069 /// (such as fetch_add of 0) can be turned into a fence followed by an
1070 /// atomic load. This may sound useless, but it makes it possible for the
1071 /// processor to keep the cacheline shared, dramatically improving
1072 /// performance. And such idempotent RMWs are useful for implementing some
1073 /// kinds of locks, see for example (justification + benchmarks):
1074 /// http://www.hpl.hp.com/techreports/2012/HPL-2012-68.pdf
1075 /// This method tries doing that transformation, returning the atomic load if
1076 /// it succeeds, and nullptr otherwise.
1077 /// If shouldExpandAtomicLoadInIR returns true on that load, it will undergo
1078 /// another round of expansion.
1079 virtual LoadInst *lowerIdempotentRMWIntoFencedLoad(AtomicRMWInst *RMWI) const {
1082 //===--------------------------------------------------------------------===//
1083 // TargetLowering Configuration Methods - These methods should be invoked by
1084 // the derived class constructor to configure this object for the target.
1087 /// \brief Reset the operation actions based on target options.
1088 virtual void resetOperationActions() {}
1091 /// Specify how the target extends the result of integer and floating point
1092 /// boolean values from i1 to a wider type. See getBooleanContents.
1093 void setBooleanContents(BooleanContent Ty) {
1094 BooleanContents = Ty;
1095 BooleanFloatContents = Ty;
1098 /// Specify how the target extends the result of integer and floating point
1099 /// boolean values from i1 to a wider type. See getBooleanContents.
1100 void setBooleanContents(BooleanContent IntTy, BooleanContent FloatTy) {
1101 BooleanContents = IntTy;
1102 BooleanFloatContents = FloatTy;
1105 /// Specify how the target extends the result of a vector boolean value from a
1106 /// vector of i1 to a wider type. See getBooleanContents.
1107 void setBooleanVectorContents(BooleanContent Ty) {
1108 BooleanVectorContents = Ty;
1111 /// Specify the target scheduling preference.
1112 void setSchedulingPreference(Sched::Preference Pref) {
1113 SchedPreferenceInfo = Pref;
1116 /// Indicate whether this target prefers to use _setjmp to implement
1117 /// llvm.setjmp or the version without _. Defaults to false.
1118 void setUseUnderscoreSetJmp(bool Val) {
1119 UseUnderscoreSetJmp = Val;
1122 /// Indicate whether this target prefers to use _longjmp to implement
1123 /// llvm.longjmp or the version without _. Defaults to false.
1124 void setUseUnderscoreLongJmp(bool Val) {
1125 UseUnderscoreLongJmp = Val;
1128 /// Indicate the number of blocks to generate jump tables rather than if
1130 void setMinimumJumpTableEntries(int Val) {
1131 MinimumJumpTableEntries = Val;
1134 /// If set to a physical register, this specifies the register that
1135 /// llvm.savestack/llvm.restorestack should save and restore.
1136 void setStackPointerRegisterToSaveRestore(unsigned R) {
1137 StackPointerRegisterToSaveRestore = R;
1140 /// If set to a physical register, this sets the register that receives the
1141 /// exception address on entry to a landing pad.
1142 void setExceptionPointerRegister(unsigned R) {
1143 ExceptionPointerRegister = R;
1146 /// If set to a physical register, this sets the register that receives the
1147 /// exception typeid on entry to a landing pad.
1148 void setExceptionSelectorRegister(unsigned R) {
1149 ExceptionSelectorRegister = R;
1152 /// Tells the code generator not to expand operations into sequences that use
1153 /// the select operations if possible.
1154 void setSelectIsExpensive(bool isExpensive = true) {
1155 SelectIsExpensive = isExpensive;
1158 /// Tells the code generator that the target has multiple (allocatable)
1159 /// condition registers that can be used to store the results of comparisons
1160 /// for use by selects and conditional branches. With multiple condition
1161 /// registers, the code generator will not aggressively sink comparisons into
1162 /// the blocks of their users.
1163 void setHasMultipleConditionRegisters(bool hasManyRegs = true) {
1164 HasMultipleConditionRegisters = hasManyRegs;
1167 /// Tells the code generator that the target has BitExtract instructions.
1168 /// The code generator will aggressively sink "shift"s into the blocks of
1169 /// their users if the users will generate "and" instructions which can be
1170 /// combined with "shift" to BitExtract instructions.
1171 void setHasExtractBitsInsn(bool hasExtractInsn = true) {
1172 HasExtractBitsInsn = hasExtractInsn;
1175 /// Tells the code generator not to expand sequence of operations into a
1176 /// separate sequences that increases the amount of flow control.
1177 void setJumpIsExpensive(bool isExpensive = true) {
1178 JumpIsExpensive = isExpensive;
1181 /// Tells the code generator that integer divide is expensive, and if
1182 /// possible, should be replaced by an alternate sequence of instructions not
1183 /// containing an integer divide.
1184 void setIntDivIsCheap(bool isCheap = true) { IntDivIsCheap = isCheap; }
1186 /// Tells the code generator that this target supports floating point
1187 /// exceptions and cares about preserving floating point exception behavior.
1188 void setHasFloatingPointExceptions(bool FPExceptions = true) {
1189 HasFloatingPointExceptions = FPExceptions;
1192 /// Tells the code generator which bitwidths to bypass.
1193 void addBypassSlowDiv(unsigned int SlowBitWidth, unsigned int FastBitWidth) {
1194 BypassSlowDivWidths[SlowBitWidth] = FastBitWidth;
1197 /// Tells the code generator that it shouldn't generate sra/srl/add/sra for a
1198 /// signed divide by power of two; let the target handle it.
1199 void setPow2SDivIsCheap(bool isCheap = true) { Pow2SDivIsCheap = isCheap; }
1201 /// Add the specified register class as an available regclass for the
1202 /// specified value type. This indicates the selector can handle values of
1203 /// that class natively.
1204 void addRegisterClass(MVT VT, const TargetRegisterClass *RC) {
1205 assert((unsigned)VT.SimpleTy < array_lengthof(RegClassForVT));
1206 AvailableRegClasses.push_back(std::make_pair(VT, RC));
1207 RegClassForVT[VT.SimpleTy] = RC;
1210 /// Remove all register classes.
1211 void clearRegisterClasses() {
1212 memset(RegClassForVT, 0,MVT::LAST_VALUETYPE * sizeof(TargetRegisterClass*));
1214 AvailableRegClasses.clear();
1217 /// \brief Remove all operation actions.
1218 void clearOperationActions() {
1221 /// Return the largest legal super-reg register class of the register class
1222 /// for the specified type and its associated "cost".
1223 virtual std::pair<const TargetRegisterClass*, uint8_t>
1224 findRepresentativeClass(MVT VT) const;
1226 /// Once all of the register classes are added, this allows us to compute
1227 /// derived properties we expose.
1228 void computeRegisterProperties();
1230 /// Indicate that the specified operation does not work with the specified
1231 /// type and indicate what to do about it.
1232 void setOperationAction(unsigned Op, MVT VT,
1233 LegalizeAction Action) {
1234 assert(Op < array_lengthof(OpActions[0]) && "Table isn't big enough!");
1235 OpActions[(unsigned)VT.SimpleTy][Op] = (uint8_t)Action;
1238 /// Indicate that the specified load with extension does not work with the
1239 /// specified type and indicate what to do about it.
1240 void setLoadExtAction(unsigned ExtType, MVT VT,
1241 LegalizeAction Action) {
1242 assert(ExtType < ISD::LAST_LOADEXT_TYPE && VT.isValid() &&
1243 "Table isn't big enough!");
1244 LoadExtActions[VT.SimpleTy][ExtType] = (uint8_t)Action;
1247 /// Indicate that the specified truncating store does not work with the
1248 /// specified type and indicate what to do about it.
1249 void setTruncStoreAction(MVT ValVT, MVT MemVT,
1250 LegalizeAction Action) {
1251 assert(ValVT.isValid() && MemVT.isValid() && "Table isn't big enough!");
1252 TruncStoreActions[ValVT.SimpleTy][MemVT.SimpleTy] = (uint8_t)Action;
1255 /// Indicate that the specified indexed load does or does not work with the
1256 /// specified type and indicate what to do abort it.
1258 /// NOTE: All indexed mode loads are initialized to Expand in
1259 /// TargetLowering.cpp
1260 void setIndexedLoadAction(unsigned IdxMode, MVT VT,
1261 LegalizeAction Action) {
1262 assert(VT.isValid() && IdxMode < ISD::LAST_INDEXED_MODE &&
1263 (unsigned)Action < 0xf && "Table isn't big enough!");
1264 // Load action are kept in the upper half.
1265 IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0xf0;
1266 IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] |= ((uint8_t)Action) <<4;
1269 /// Indicate that the specified indexed store does or does not work with the
1270 /// specified type and indicate what to do about it.
1272 /// NOTE: All indexed mode stores are initialized to Expand in
1273 /// TargetLowering.cpp
1274 void setIndexedStoreAction(unsigned IdxMode, MVT VT,
1275 LegalizeAction Action) {
1276 assert(VT.isValid() && IdxMode < ISD::LAST_INDEXED_MODE &&
1277 (unsigned)Action < 0xf && "Table isn't big enough!");
1278 // Store action are kept in the lower half.
1279 IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0x0f;
1280 IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] |= ((uint8_t)Action);
1283 /// Indicate that the specified condition code is or isn't supported on the
1284 /// target and indicate what to do about it.
1285 void setCondCodeAction(ISD::CondCode CC, MVT VT,
1286 LegalizeAction Action) {
1287 assert(VT.isValid() && (unsigned)CC < array_lengthof(CondCodeActions) &&
1288 "Table isn't big enough!");
1289 /// The lower 5 bits of the SimpleTy index into Nth 2bit set from the 32-bit
1290 /// value and the upper 27 bits index into the second dimension of the array
1291 /// to select what 32-bit value to use.
1292 uint32_t Shift = 2 * (VT.SimpleTy & 0xF);
1293 CondCodeActions[CC][VT.SimpleTy >> 4] &= ~((uint32_t)0x3 << Shift);
1294 CondCodeActions[CC][VT.SimpleTy >> 4] |= (uint32_t)Action << Shift;
1297 /// If Opc/OrigVT is specified as being promoted, the promotion code defaults
1298 /// to trying a larger integer/fp until it can find one that works. If that
1299 /// default is insufficient, this method can be used by the target to override
1301 void AddPromotedToType(unsigned Opc, MVT OrigVT, MVT DestVT) {
1302 PromoteToType[std::make_pair(Opc, OrigVT.SimpleTy)] = DestVT.SimpleTy;
1305 /// Targets should invoke this method for each target independent node that
1306 /// they want to provide a custom DAG combiner for by implementing the
1307 /// PerformDAGCombine virtual method.
1308 void setTargetDAGCombine(ISD::NodeType NT) {
1309 assert(unsigned(NT >> 3) < array_lengthof(TargetDAGCombineArray));
1310 TargetDAGCombineArray[NT >> 3] |= 1 << (NT&7);
1313 /// Set the target's required jmp_buf buffer size (in bytes); default is 200
1314 void setJumpBufSize(unsigned Size) {
1318 /// Set the target's required jmp_buf buffer alignment (in bytes); default is
1320 void setJumpBufAlignment(unsigned Align) {
1321 JumpBufAlignment = Align;
1324 /// Set the target's minimum function alignment (in log2(bytes))
1325 void setMinFunctionAlignment(unsigned Align) {
1326 MinFunctionAlignment = Align;
1329 /// Set the target's preferred function alignment. This should be set if
1330 /// there is a performance benefit to higher-than-minimum alignment (in
1332 void setPrefFunctionAlignment(unsigned Align) {
1333 PrefFunctionAlignment = Align;
1336 /// Set the target's preferred loop alignment. Default alignment is zero, it
1337 /// means the target does not care about loop alignment. The alignment is
1338 /// specified in log2(bytes). The target may also override
1339 /// getPrefLoopAlignment to provide per-loop values.
1340 void setPrefLoopAlignment(unsigned Align) {
1341 PrefLoopAlignment = Align;
1344 /// Set the minimum stack alignment of an argument (in log2(bytes)).
1345 void setMinStackArgumentAlignment(unsigned Align) {
1346 MinStackArgumentAlignment = Align;
1349 /// Set if the DAG builder should automatically insert fences and reduce the
1350 /// order of atomic memory operations to Monotonic.
1351 void setInsertFencesForAtomic(bool fence) {
1352 InsertFencesForAtomic = fence;
1356 //===--------------------------------------------------------------------===//
1357 // Addressing mode description hooks (used by LSR etc).
1360 /// CodeGenPrepare sinks address calculations into the same BB as Load/Store
1361 /// instructions reading the address. This allows as much computation as
1362 /// possible to be done in the address mode for that operand. This hook lets
1363 /// targets also pass back when this should be done on intrinsics which
1365 virtual bool GetAddrModeArguments(IntrinsicInst * /*I*/,
1366 SmallVectorImpl<Value*> &/*Ops*/,
1367 Type *&/*AccessTy*/) const {
1371 /// This represents an addressing mode of:
1372 /// BaseGV + BaseOffs + BaseReg + Scale*ScaleReg
1373 /// If BaseGV is null, there is no BaseGV.
1374 /// If BaseOffs is zero, there is no base offset.
1375 /// If HasBaseReg is false, there is no base register.
1376 /// If Scale is zero, there is no ScaleReg. Scale of 1 indicates a reg with
1379 GlobalValue *BaseGV;
1383 AddrMode() : BaseGV(nullptr), BaseOffs(0), HasBaseReg(false), Scale(0) {}
1386 /// Return true if the addressing mode represented by AM is legal for this
1387 /// target, for a load/store of the specified type.
1389 /// The type may be VoidTy, in which case only return true if the addressing
1390 /// mode is legal for a load/store of any legal type. TODO: Handle
1391 /// pre/postinc as well.
1392 virtual bool isLegalAddressingMode(const AddrMode &AM, Type *Ty) const;
1394 /// \brief Return the cost of the scaling factor used in the addressing mode
1395 /// represented by AM for this target, for a load/store of the specified type.
1397 /// If the AM is supported, the return value must be >= 0.
1398 /// If the AM is not supported, it returns a negative value.
1399 /// TODO: Handle pre/postinc as well.
1400 virtual int getScalingFactorCost(const AddrMode &AM, Type *Ty) const {
1401 // Default: assume that any scaling factor used in a legal AM is free.
1402 if (isLegalAddressingMode(AM, Ty)) return 0;
1406 /// Return true if the specified immediate is legal icmp immediate, that is
1407 /// the target has icmp instructions which can compare a register against the
1408 /// immediate without having to materialize the immediate into a register.
1409 virtual bool isLegalICmpImmediate(int64_t) const {
1413 /// Return true if the specified immediate is legal add immediate, that is the
1414 /// target has add instructions which can add a register with the immediate
1415 /// without having to materialize the immediate into a register.
1416 virtual bool isLegalAddImmediate(int64_t) const {
1420 /// Return true if it's significantly cheaper to shift a vector by a uniform
1421 /// scalar than by an amount which will vary across each lane. On x86, for
1422 /// example, there is a "psllw" instruction for the former case, but no simple
1423 /// instruction for a general "a << b" operation on vectors.
1424 virtual bool isVectorShiftByScalarCheap(Type *Ty) const {
1428 /// Return true if it's free to truncate a value of type Ty1 to type
1429 /// Ty2. e.g. On x86 it's free to truncate a i32 value in register EAX to i16
1430 /// by referencing its sub-register AX.
1431 virtual bool isTruncateFree(Type * /*Ty1*/, Type * /*Ty2*/) const {
1435 /// Return true if a truncation from Ty1 to Ty2 is permitted when deciding
1436 /// whether a call is in tail position. Typically this means that both results
1437 /// would be assigned to the same register or stack slot, but it could mean
1438 /// the target performs adequate checks of its own before proceeding with the
1440 virtual bool allowTruncateForTailCall(Type * /*Ty1*/, Type * /*Ty2*/) const {
1444 virtual bool isTruncateFree(EVT /*VT1*/, EVT /*VT2*/) const {
1448 /// Return true if any actual instruction that defines a value of type Ty1
1449 /// implicitly zero-extends the value to Ty2 in the result register.
1451 /// This does not necessarily include registers defined in unknown ways, such
1452 /// as incoming arguments, or copies from unknown virtual registers. Also, if
1453 /// isTruncateFree(Ty2, Ty1) is true, this does not necessarily apply to
1454 /// truncate instructions. e.g. on x86-64, all instructions that define 32-bit
1455 /// values implicit zero-extend the result out to 64 bits.
1456 virtual bool isZExtFree(Type * /*Ty1*/, Type * /*Ty2*/) const {
1460 virtual bool isZExtFree(EVT /*VT1*/, EVT /*VT2*/) const {
1464 /// Return true if the target supplies and combines to a paired load
1465 /// two loaded values of type LoadedType next to each other in memory.
1466 /// RequiredAlignment gives the minimal alignment constraints that must be met
1467 /// to be able to select this paired load.
1469 /// This information is *not* used to generate actual paired loads, but it is
1470 /// used to generate a sequence of loads that is easier to combine into a
1472 /// For instance, something like this:
1473 /// a = load i64* addr
1474 /// b = trunc i64 a to i32
1475 /// c = lshr i64 a, 32
1476 /// d = trunc i64 c to i32
1477 /// will be optimized into:
1478 /// b = load i32* addr1
1479 /// d = load i32* addr2
1480 /// Where addr1 = addr2 +/- sizeof(i32).
1482 /// In other words, unless the target performs a post-isel load combining,
1483 /// this information should not be provided because it will generate more
1485 virtual bool hasPairedLoad(Type * /*LoadedType*/,
1486 unsigned & /*RequiredAligment*/) const {
1490 virtual bool hasPairedLoad(EVT /*LoadedType*/,
1491 unsigned & /*RequiredAligment*/) const {
1495 /// Return true if zero-extending the specific node Val to type VT2 is free
1496 /// (either because it's implicitly zero-extended such as ARM ldrb / ldrh or
1497 /// because it's folded such as X86 zero-extending loads).
1498 virtual bool isZExtFree(SDValue Val, EVT VT2) const {
1499 return isZExtFree(Val.getValueType(), VT2);
1502 /// Return true if an fneg operation is free to the point where it is never
1503 /// worthwhile to replace it with a bitwise operation.
1504 virtual bool isFNegFree(EVT VT) const {
1505 assert(VT.isFloatingPoint());
1509 /// Return true if an fabs operation is free to the point where it is never
1510 /// worthwhile to replace it with a bitwise operation.
1511 virtual bool isFAbsFree(EVT VT) const {
1512 assert(VT.isFloatingPoint());
1516 /// Return true if an FMA operation is faster than a pair of fmul and fadd
1517 /// instructions. fmuladd intrinsics will be expanded to FMAs when this method
1518 /// returns true, otherwise fmuladd is expanded to fmul + fadd.
1520 /// NOTE: This may be called before legalization on types for which FMAs are
1521 /// not legal, but should return true if those types will eventually legalize
1522 /// to types that support FMAs. After legalization, it will only be called on
1523 /// types that support FMAs (via Legal or Custom actions)
1524 virtual bool isFMAFasterThanFMulAndFAdd(EVT) const {
1528 /// Return true if it's profitable to narrow operations of type VT1 to
1529 /// VT2. e.g. on x86, it's profitable to narrow from i32 to i8 but not from
1531 virtual bool isNarrowingProfitable(EVT /*VT1*/, EVT /*VT2*/) const {
1535 /// \brief Return true if it is beneficial to convert a load of a constant to
1536 /// just the constant itself.
1537 /// On some targets it might be more efficient to use a combination of
1538 /// arithmetic instructions to materialize the constant instead of loading it
1539 /// from a constant pool.
1540 virtual bool shouldConvertConstantLoadToIntImm(const APInt &Imm,
1545 /// Return true if EXTRACT_SUBVECTOR is cheap for this result type
1546 /// with this index. This is needed because EXTRACT_SUBVECTOR usually
1547 /// has custom lowering that depends on the index of the first element,
1548 /// and only the target knows which lowering is cheap.
1549 virtual bool isExtractSubvectorCheap(EVT ResVT, unsigned Index) const {
1553 //===--------------------------------------------------------------------===//
1554 // Runtime Library hooks
1557 /// Rename the default libcall routine name for the specified libcall.
1558 void setLibcallName(RTLIB::Libcall Call, const char *Name) {
1559 LibcallRoutineNames[Call] = Name;
1562 /// Get the libcall routine name for the specified libcall.
1563 const char *getLibcallName(RTLIB::Libcall Call) const {
1564 return LibcallRoutineNames[Call];
1567 /// Override the default CondCode to be used to test the result of the
1568 /// comparison libcall against zero.
1569 void setCmpLibcallCC(RTLIB::Libcall Call, ISD::CondCode CC) {
1570 CmpLibcallCCs[Call] = CC;
1573 /// Get the CondCode that's to be used to test the result of the comparison
1574 /// libcall against zero.
1575 ISD::CondCode getCmpLibcallCC(RTLIB::Libcall Call) const {
1576 return CmpLibcallCCs[Call];
1579 /// Set the CallingConv that should be used for the specified libcall.
1580 void setLibcallCallingConv(RTLIB::Libcall Call, CallingConv::ID CC) {
1581 LibcallCallingConvs[Call] = CC;
1584 /// Get the CallingConv that should be used for the specified libcall.
1585 CallingConv::ID getLibcallCallingConv(RTLIB::Libcall Call) const {
1586 return LibcallCallingConvs[Call];
1590 const TargetMachine &TM;
1591 const DataLayout *DL;
1593 /// True if this is a little endian target.
1594 bool IsLittleEndian;
1596 /// Tells the code generator not to expand operations into sequences that use
1597 /// the select operations if possible.
1598 bool SelectIsExpensive;
1600 /// Tells the code generator that the target has multiple (allocatable)
1601 /// condition registers that can be used to store the results of comparisons
1602 /// for use by selects and conditional branches. With multiple condition
1603 /// registers, the code generator will not aggressively sink comparisons into
1604 /// the blocks of their users.
1605 bool HasMultipleConditionRegisters;
1607 /// Tells the code generator that the target has BitExtract instructions.
1608 /// The code generator will aggressively sink "shift"s into the blocks of
1609 /// their users if the users will generate "and" instructions which can be
1610 /// combined with "shift" to BitExtract instructions.
1611 bool HasExtractBitsInsn;
1613 /// Tells the code generator not to expand integer divides by constants into a
1614 /// sequence of muls, adds, and shifts. This is a hack until a real cost
1615 /// model is in place. If we ever optimize for size, this will be set to true
1616 /// unconditionally.
1619 /// Tells the code generator to bypass slow divide or remainder
1620 /// instructions. For example, BypassSlowDivWidths[32,8] tells the code
1621 /// generator to bypass 32-bit integer div/rem with an 8-bit unsigned integer
1622 /// div/rem when the operands are positive and less than 256.
1623 DenseMap <unsigned int, unsigned int> BypassSlowDivWidths;
1625 /// Tells the code generator that it shouldn't generate sra/srl/add/sra for a
1626 /// signed divide by power of two; let the target handle it.
1627 bool Pow2SDivIsCheap;
1629 /// Tells the code generator that it shouldn't generate extra flow control
1630 /// instructions and should attempt to combine flow control instructions via
1632 bool JumpIsExpensive;
1634 /// Whether the target supports or cares about preserving floating point
1635 /// exception behavior.
1636 bool HasFloatingPointExceptions;
1638 /// This target prefers to use _setjmp to implement llvm.setjmp.
1640 /// Defaults to false.
1641 bool UseUnderscoreSetJmp;
1643 /// This target prefers to use _longjmp to implement llvm.longjmp.
1645 /// Defaults to false.
1646 bool UseUnderscoreLongJmp;
1648 /// Number of blocks threshold to use jump tables.
1649 int MinimumJumpTableEntries;
1651 /// Information about the contents of the high-bits in boolean values held in
1652 /// a type wider than i1. See getBooleanContents.
1653 BooleanContent BooleanContents;
1655 /// Information about the contents of the high-bits in boolean values held in
1656 /// a type wider than i1. See getBooleanContents.
1657 BooleanContent BooleanFloatContents;
1659 /// Information about the contents of the high-bits in boolean vector values
1660 /// when the element type is wider than i1. See getBooleanContents.
1661 BooleanContent BooleanVectorContents;
1663 /// The target scheduling preference: shortest possible total cycles or lowest
1665 Sched::Preference SchedPreferenceInfo;
1667 /// The size, in bytes, of the target's jmp_buf buffers
1668 unsigned JumpBufSize;
1670 /// The alignment, in bytes, of the target's jmp_buf buffers
1671 unsigned JumpBufAlignment;
1673 /// The minimum alignment that any argument on the stack needs to have.
1674 unsigned MinStackArgumentAlignment;
1676 /// The minimum function alignment (used when optimizing for size, and to
1677 /// prevent explicitly provided alignment from leading to incorrect code).
1678 unsigned MinFunctionAlignment;
1680 /// The preferred function alignment (used when alignment unspecified and
1681 /// optimizing for speed).
1682 unsigned PrefFunctionAlignment;
1684 /// The preferred loop alignment.
1685 unsigned PrefLoopAlignment;
1687 /// Whether the DAG builder should automatically insert fences and reduce
1688 /// ordering for atomics. (This will be set for for most architectures with
1689 /// weak memory ordering.)
1690 bool InsertFencesForAtomic;
1692 /// If set to a physical register, this specifies the register that
1693 /// llvm.savestack/llvm.restorestack should save and restore.
1694 unsigned StackPointerRegisterToSaveRestore;
1696 /// If set to a physical register, this specifies the register that receives
1697 /// the exception address on entry to a landing pad.
1698 unsigned ExceptionPointerRegister;
1700 /// If set to a physical register, this specifies the register that receives
1701 /// the exception typeid on entry to a landing pad.
1702 unsigned ExceptionSelectorRegister;
1704 /// This indicates the default register class to use for each ValueType the
1705 /// target supports natively.
1706 const TargetRegisterClass *RegClassForVT[MVT::LAST_VALUETYPE];
1707 unsigned char NumRegistersForVT[MVT::LAST_VALUETYPE];
1708 MVT RegisterTypeForVT[MVT::LAST_VALUETYPE];
1710 /// This indicates the "representative" register class to use for each
1711 /// ValueType the target supports natively. This information is used by the
1712 /// scheduler to track register pressure. By default, the representative
1713 /// register class is the largest legal super-reg register class of the
1714 /// register class of the specified type. e.g. On x86, i8, i16, and i32's
1715 /// representative class would be GR32.
1716 const TargetRegisterClass *RepRegClassForVT[MVT::LAST_VALUETYPE];
1718 /// This indicates the "cost" of the "representative" register class for each
1719 /// ValueType. The cost is used by the scheduler to approximate register
1721 uint8_t RepRegClassCostForVT[MVT::LAST_VALUETYPE];
1723 /// For any value types we are promoting or expanding, this contains the value
1724 /// type that we are changing to. For Expanded types, this contains one step
1725 /// of the expand (e.g. i64 -> i32), even if there are multiple steps required
1726 /// (e.g. i64 -> i16). For types natively supported by the system, this holds
1727 /// the same type (e.g. i32 -> i32).
1728 MVT TransformToType[MVT::LAST_VALUETYPE];
1730 /// For each operation and each value type, keep a LegalizeAction that
1731 /// indicates how instruction selection should deal with the operation. Most
1732 /// operations are Legal (aka, supported natively by the target), but
1733 /// operations that are not should be described. Note that operations on
1734 /// non-legal value types are not described here.
1735 uint8_t OpActions[MVT::LAST_VALUETYPE][ISD::BUILTIN_OP_END];
1737 /// For each load extension type and each value type, keep a LegalizeAction
1738 /// that indicates how instruction selection should deal with a load of a
1739 /// specific value type and extension type.
1740 uint8_t LoadExtActions[MVT::LAST_VALUETYPE][ISD::LAST_LOADEXT_TYPE];
1742 /// For each value type pair keep a LegalizeAction that indicates whether a
1743 /// truncating store of a specific value type and truncating type is legal.
1744 uint8_t TruncStoreActions[MVT::LAST_VALUETYPE][MVT::LAST_VALUETYPE];
1746 /// For each indexed mode and each value type, keep a pair of LegalizeAction
1747 /// that indicates how instruction selection should deal with the load /
1750 /// The first dimension is the value_type for the reference. The second
1751 /// dimension represents the various modes for load store.
1752 uint8_t IndexedModeActions[MVT::LAST_VALUETYPE][ISD::LAST_INDEXED_MODE];
1754 /// For each condition code (ISD::CondCode) keep a LegalizeAction that
1755 /// indicates how instruction selection should deal with the condition code.
1757 /// Because each CC action takes up 2 bits, we need to have the array size be
1758 /// large enough to fit all of the value types. This can be done by rounding
1759 /// up the MVT::LAST_VALUETYPE value to the next multiple of 16.
1760 uint32_t CondCodeActions[ISD::SETCC_INVALID][(MVT::LAST_VALUETYPE + 15) / 16];
1762 ValueTypeActionImpl ValueTypeActions;
1766 getTypeConversion(LLVMContext &Context, EVT VT) const {
1767 // If this is a simple type, use the ComputeRegisterProp mechanism.
1768 if (VT.isSimple()) {
1769 MVT SVT = VT.getSimpleVT();
1770 assert((unsigned)SVT.SimpleTy < array_lengthof(TransformToType));
1771 MVT NVT = TransformToType[SVT.SimpleTy];
1772 LegalizeTypeAction LA = ValueTypeActions.getTypeAction(SVT);
1775 (LA == TypeLegal || LA == TypeSoftenFloat ||
1776 ValueTypeActions.getTypeAction(NVT) != TypePromoteInteger)
1777 && "Promote may not follow Expand or Promote");
1779 if (LA == TypeSplitVector)
1780 return LegalizeKind(LA, EVT::getVectorVT(Context,
1781 SVT.getVectorElementType(),
1782 SVT.getVectorNumElements()/2));
1783 if (LA == TypeScalarizeVector)
1784 return LegalizeKind(LA, SVT.getVectorElementType());
1785 return LegalizeKind(LA, NVT);
1788 // Handle Extended Scalar Types.
1789 if (!VT.isVector()) {
1790 assert(VT.isInteger() && "Float types must be simple");
1791 unsigned BitSize = VT.getSizeInBits();
1792 // First promote to a power-of-two size, then expand if necessary.
1793 if (BitSize < 8 || !isPowerOf2_32(BitSize)) {
1794 EVT NVT = VT.getRoundIntegerType(Context);
1795 assert(NVT != VT && "Unable to round integer VT");
1796 LegalizeKind NextStep = getTypeConversion(Context, NVT);
1797 // Avoid multi-step promotion.
1798 if (NextStep.first == TypePromoteInteger) return NextStep;
1799 // Return rounded integer type.
1800 return LegalizeKind(TypePromoteInteger, NVT);
1803 return LegalizeKind(TypeExpandInteger,
1804 EVT::getIntegerVT(Context, VT.getSizeInBits()/2));
1807 // Handle vector types.
1808 unsigned NumElts = VT.getVectorNumElements();
1809 EVT EltVT = VT.getVectorElementType();
1811 // Vectors with only one element are always scalarized.
1813 return LegalizeKind(TypeScalarizeVector, EltVT);
1815 // Try to widen vector elements until the element type is a power of two and
1816 // promote it to a legal type later on, for example:
1817 // <3 x i8> -> <4 x i8> -> <4 x i32>
1818 if (EltVT.isInteger()) {
1819 // Vectors with a number of elements that is not a power of two are always
1820 // widened, for example <3 x i8> -> <4 x i8>.
1821 if (!VT.isPow2VectorType()) {
1822 NumElts = (unsigned)NextPowerOf2(NumElts);
1823 EVT NVT = EVT::getVectorVT(Context, EltVT, NumElts);
1824 return LegalizeKind(TypeWidenVector, NVT);
1827 // Examine the element type.
1828 LegalizeKind LK = getTypeConversion(Context, EltVT);
1830 // If type is to be expanded, split the vector.
1831 // <4 x i140> -> <2 x i140>
1832 if (LK.first == TypeExpandInteger)
1833 return LegalizeKind(TypeSplitVector,
1834 EVT::getVectorVT(Context, EltVT, NumElts / 2));
1836 // Promote the integer element types until a legal vector type is found
1837 // or until the element integer type is too big. If a legal type was not
1838 // found, fallback to the usual mechanism of widening/splitting the
1840 EVT OldEltVT = EltVT;
1842 // Increase the bitwidth of the element to the next pow-of-two
1843 // (which is greater than 8 bits).
1844 EltVT = EVT::getIntegerVT(Context, 1 + EltVT.getSizeInBits()
1845 ).getRoundIntegerType(Context);
1847 // Stop trying when getting a non-simple element type.
1848 // Note that vector elements may be greater than legal vector element
1849 // types. Example: X86 XMM registers hold 64bit element on 32bit
1851 if (!EltVT.isSimple()) break;
1853 // Build a new vector type and check if it is legal.
1854 MVT NVT = MVT::getVectorVT(EltVT.getSimpleVT(), NumElts);
1855 // Found a legal promoted vector type.
1856 if (NVT != MVT() && ValueTypeActions.getTypeAction(NVT) == TypeLegal)
1857 return LegalizeKind(TypePromoteInteger,
1858 EVT::getVectorVT(Context, EltVT, NumElts));
1861 // Reset the type to the unexpanded type if we did not find a legal vector
1862 // type with a promoted vector element type.
1866 // Try to widen the vector until a legal type is found.
1867 // If there is no wider legal type, split the vector.
1869 // Round up to the next power of 2.
1870 NumElts = (unsigned)NextPowerOf2(NumElts);
1872 // If there is no simple vector type with this many elements then there
1873 // cannot be a larger legal vector type. Note that this assumes that
1874 // there are no skipped intermediate vector types in the simple types.
1875 if (!EltVT.isSimple()) break;
1876 MVT LargerVector = MVT::getVectorVT(EltVT.getSimpleVT(), NumElts);
1877 if (LargerVector == MVT()) break;
1879 // If this type is legal then widen the vector.
1880 if (ValueTypeActions.getTypeAction(LargerVector) == TypeLegal)
1881 return LegalizeKind(TypeWidenVector, LargerVector);
1884 // Widen odd vectors to next power of two.
1885 if (!VT.isPow2VectorType()) {
1886 EVT NVT = VT.getPow2VectorType(Context);
1887 return LegalizeKind(TypeWidenVector, NVT);
1890 // Vectors with illegal element types are expanded.
1891 EVT NVT = EVT::getVectorVT(Context, EltVT, VT.getVectorNumElements() / 2);
1892 return LegalizeKind(TypeSplitVector, NVT);
1896 std::vector<std::pair<MVT, const TargetRegisterClass*> > AvailableRegClasses;
1898 /// Targets can specify ISD nodes that they would like PerformDAGCombine
1899 /// callbacks for by calling setTargetDAGCombine(), which sets a bit in this
1902 TargetDAGCombineArray[(ISD::BUILTIN_OP_END+CHAR_BIT-1)/CHAR_BIT];
1904 /// For operations that must be promoted to a specific type, this holds the
1905 /// destination type. This map should be sparse, so don't hold it as an
1908 /// Targets add entries to this map with AddPromotedToType(..), clients access
1909 /// this with getTypeToPromoteTo(..).
1910 std::map<std::pair<unsigned, MVT::SimpleValueType>, MVT::SimpleValueType>
1913 /// Stores the name each libcall.
1914 const char *LibcallRoutineNames[RTLIB::UNKNOWN_LIBCALL];
1916 /// The ISD::CondCode that should be used to test the result of each of the
1917 /// comparison libcall against zero.
1918 ISD::CondCode CmpLibcallCCs[RTLIB::UNKNOWN_LIBCALL];
1920 /// Stores the CallingConv that should be used for each libcall.
1921 CallingConv::ID LibcallCallingConvs[RTLIB::UNKNOWN_LIBCALL];
1924 /// \brief Specify maximum number of store instructions per memset call.
1926 /// When lowering \@llvm.memset this field specifies the maximum number of
1927 /// store operations that may be substituted for the call to memset. Targets
1928 /// must set this value based on the cost threshold for that target. Targets
1929 /// should assume that the memset will be done using as many of the largest
1930 /// store operations first, followed by smaller ones, if necessary, per
1931 /// alignment restrictions. For example, storing 9 bytes on a 32-bit machine
1932 /// with 16-bit alignment would result in four 2-byte stores and one 1-byte
1933 /// store. This only applies to setting a constant array of a constant size.
1934 unsigned MaxStoresPerMemset;
1936 /// Maximum number of stores operations that may be substituted for the call
1937 /// to memset, used for functions with OptSize attribute.
1938 unsigned MaxStoresPerMemsetOptSize;
1940 /// \brief Specify maximum bytes of store instructions per memcpy call.
1942 /// When lowering \@llvm.memcpy this field specifies the maximum number of
1943 /// store operations that may be substituted for a call to memcpy. Targets
1944 /// must set this value based on the cost threshold for that target. Targets
1945 /// should assume that the memcpy will be done using as many of the largest
1946 /// store operations first, followed by smaller ones, if necessary, per
1947 /// alignment restrictions. For example, storing 7 bytes on a 32-bit machine
1948 /// with 32-bit alignment would result in one 4-byte store, a one 2-byte store
1949 /// and one 1-byte store. This only applies to copying a constant array of
1951 unsigned MaxStoresPerMemcpy;
1953 /// Maximum number of store operations that may be substituted for a call to
1954 /// memcpy, used for functions with OptSize attribute.
1955 unsigned MaxStoresPerMemcpyOptSize;
1957 /// \brief Specify maximum bytes of store instructions per memmove call.
1959 /// When lowering \@llvm.memmove this field specifies the maximum number of
1960 /// store instructions that may be substituted for a call to memmove. Targets
1961 /// must set this value based on the cost threshold for that target. Targets
1962 /// should assume that the memmove will be done using as many of the largest
1963 /// store operations first, followed by smaller ones, if necessary, per
1964 /// alignment restrictions. For example, moving 9 bytes on a 32-bit machine
1965 /// with 8-bit alignment would result in nine 1-byte stores. This only
1966 /// applies to copying a constant array of constant size.
1967 unsigned MaxStoresPerMemmove;
1969 /// Maximum number of store instructions that may be substituted for a call to
1970 /// memmove, used for functions with OpSize attribute.
1971 unsigned MaxStoresPerMemmoveOptSize;
1973 /// Tells the code generator that select is more expensive than a branch if
1974 /// the branch is usually predicted right.
1975 bool PredictableSelectIsExpensive;
1977 /// MaskAndBranchFoldingIsLegal - Indicates if the target supports folding
1978 /// a mask of a single bit, a compare, and a branch into a single instruction.
1979 bool MaskAndBranchFoldingIsLegal;
1981 /// \see enableExtLdPromotion.
1982 bool EnableExtLdPromotion;
1985 /// Return true if the value types that can be represented by the specified
1986 /// register class are all legal.
1987 bool isLegalRC(const TargetRegisterClass *RC) const;
1989 /// Replace/modify any TargetFrameIndex operands with a targte-dependent
1990 /// sequence of memory operands that is recognized by PrologEpilogInserter.
1991 MachineBasicBlock *emitPatchPoint(MachineInstr *MI, MachineBasicBlock *MBB) const;
1994 /// This class defines information used to lower LLVM code to legal SelectionDAG
1995 /// operators that the target instruction selector can accept natively.
1997 /// This class also defines callbacks that targets must implement to lower
1998 /// target-specific constructs to SelectionDAG operators.
1999 class TargetLowering : public TargetLoweringBase {
2000 TargetLowering(const TargetLowering&) LLVM_DELETED_FUNCTION;
2001 void operator=(const TargetLowering&) LLVM_DELETED_FUNCTION;
2004 /// NOTE: The TargetMachine owns TLOF.
2005 explicit TargetLowering(const TargetMachine &TM);
2007 /// Returns true by value, base pointer and offset pointer and addressing mode
2008 /// by reference if the node's address can be legally represented as
2009 /// pre-indexed load / store address.
2010 virtual bool getPreIndexedAddressParts(SDNode * /*N*/, SDValue &/*Base*/,
2011 SDValue &/*Offset*/,
2012 ISD::MemIndexedMode &/*AM*/,
2013 SelectionDAG &/*DAG*/) const {
2017 /// Returns true by value, base pointer and offset pointer and addressing mode
2018 /// by reference if this node can be combined with a load / store to form a
2019 /// post-indexed load / store.
2020 virtual bool getPostIndexedAddressParts(SDNode * /*N*/, SDNode * /*Op*/,
2022 SDValue &/*Offset*/,
2023 ISD::MemIndexedMode &/*AM*/,
2024 SelectionDAG &/*DAG*/) const {
2028 /// Return the entry encoding for a jump table in the current function. The
2029 /// returned value is a member of the MachineJumpTableInfo::JTEntryKind enum.
2030 virtual unsigned getJumpTableEncoding() const;
2032 virtual const MCExpr *
2033 LowerCustomJumpTableEntry(const MachineJumpTableInfo * /*MJTI*/,
2034 const MachineBasicBlock * /*MBB*/, unsigned /*uid*/,
2035 MCContext &/*Ctx*/) const {
2036 llvm_unreachable("Need to implement this hook if target has custom JTIs");
2039 /// Returns relocation base for the given PIC jumptable.
2040 virtual SDValue getPICJumpTableRelocBase(SDValue Table,
2041 SelectionDAG &DAG) const;
2043 /// This returns the relocation base for the given PIC jumptable, the same as
2044 /// getPICJumpTableRelocBase, but as an MCExpr.
2045 virtual const MCExpr *
2046 getPICJumpTableRelocBaseExpr(const MachineFunction *MF,
2047 unsigned JTI, MCContext &Ctx) const;
2049 /// Return true if folding a constant offset with the given GlobalAddress is
2050 /// legal. It is frequently not legal in PIC relocation models.
2051 virtual bool isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const;
2053 bool isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,
2054 SDValue &Chain) const;
2056 void softenSetCCOperands(SelectionDAG &DAG, EVT VT,
2057 SDValue &NewLHS, SDValue &NewRHS,
2058 ISD::CondCode &CCCode, SDLoc DL) const;
2060 /// Returns a pair of (return value, chain).
2061 std::pair<SDValue, SDValue> makeLibCall(SelectionDAG &DAG, RTLIB::Libcall LC,
2062 EVT RetVT, const SDValue *Ops,
2063 unsigned NumOps, bool isSigned,
2064 SDLoc dl, bool doesNotReturn = false,
2065 bool isReturnValueUsed = true) const;
2067 //===--------------------------------------------------------------------===//
2068 // TargetLowering Optimization Methods
2071 /// A convenience struct that encapsulates a DAG, and two SDValues for
2072 /// returning information from TargetLowering to its clients that want to
2074 struct TargetLoweringOpt {
2081 explicit TargetLoweringOpt(SelectionDAG &InDAG,
2083 DAG(InDAG), LegalTys(LT), LegalOps(LO) {}
2085 bool LegalTypes() const { return LegalTys; }
2086 bool LegalOperations() const { return LegalOps; }
2088 bool CombineTo(SDValue O, SDValue N) {
2094 /// Check to see if the specified operand of the specified instruction is a
2095 /// constant integer. If so, check to see if there are any bits set in the
2096 /// constant that are not demanded. If so, shrink the constant and return
2098 bool ShrinkDemandedConstant(SDValue Op, const APInt &Demanded);
2100 /// Convert x+y to (VT)((SmallVT)x+(SmallVT)y) if the casts are free. This
2101 /// uses isZExtFree and ZERO_EXTEND for the widening cast, but it could be
2102 /// generalized for targets with other types of implicit widening casts.
2103 bool ShrinkDemandedOp(SDValue Op, unsigned BitWidth, const APInt &Demanded,
2107 /// Look at Op. At this point, we know that only the DemandedMask bits of the
2108 /// result of Op are ever used downstream. If we can use this information to
2109 /// simplify Op, create a new simplified DAG node and return true, returning
2110 /// the original and new nodes in Old and New. Otherwise, analyze the
2111 /// expression and return a mask of KnownOne and KnownZero bits for the
2112 /// expression (used to simplify the caller). The KnownZero/One bits may only
2113 /// be accurate for those bits in the DemandedMask.
2114 bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedMask,
2115 APInt &KnownZero, APInt &KnownOne,
2116 TargetLoweringOpt &TLO, unsigned Depth = 0) const;
2118 /// Determine which of the bits specified in Mask are known to be either zero
2119 /// or one and return them in the KnownZero/KnownOne bitsets.
2120 virtual void computeKnownBitsForTargetNode(const SDValue Op,
2123 const SelectionDAG &DAG,
2124 unsigned Depth = 0) const;
2126 /// This method can be implemented by targets that want to expose additional
2127 /// information about sign bits to the DAG Combiner.
2128 virtual unsigned ComputeNumSignBitsForTargetNode(SDValue Op,
2129 const SelectionDAG &DAG,
2130 unsigned Depth = 0) const;
2132 struct DAGCombinerInfo {
2133 void *DC; // The DAG Combiner object.
2135 bool CalledByLegalizer;
2139 DAGCombinerInfo(SelectionDAG &dag, CombineLevel level, bool cl, void *dc)
2140 : DC(dc), Level(level), CalledByLegalizer(cl), DAG(dag) {}
2142 bool isBeforeLegalize() const { return Level == BeforeLegalizeTypes; }
2143 bool isBeforeLegalizeOps() const { return Level < AfterLegalizeVectorOps; }
2144 bool isAfterLegalizeVectorOps() const {
2145 return Level == AfterLegalizeDAG;
2147 CombineLevel getDAGCombineLevel() { return Level; }
2148 bool isCalledByLegalizer() const { return CalledByLegalizer; }
2150 void AddToWorklist(SDNode *N);
2151 void RemoveFromWorklist(SDNode *N);
2152 SDValue CombineTo(SDNode *N, const std::vector<SDValue> &To,
2154 SDValue CombineTo(SDNode *N, SDValue Res, bool AddTo = true);
2155 SDValue CombineTo(SDNode *N, SDValue Res0, SDValue Res1, bool AddTo = true);
2157 void CommitTargetLoweringOpt(const TargetLoweringOpt &TLO);
2160 /// Return if the N is a constant or constant vector equal to the true value
2161 /// from getBooleanContents().
2162 bool isConstTrueVal(const SDNode *N) const;
2164 /// Return if the N is a constant or constant vector equal to the false value
2165 /// from getBooleanContents().
2166 bool isConstFalseVal(const SDNode *N) const;
2168 /// Try to simplify a setcc built with the specified operands and cc. If it is
2169 /// unable to simplify it, return a null SDValue.
2170 SDValue SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
2171 ISD::CondCode Cond, bool foldBooleans,
2172 DAGCombinerInfo &DCI, SDLoc dl) const;
2174 /// Returns true (and the GlobalValue and the offset) if the node is a
2175 /// GlobalAddress + offset.
2177 isGAPlusOffset(SDNode *N, const GlobalValue* &GA, int64_t &Offset) const;
2179 /// This method will be invoked for all target nodes and for any
2180 /// target-independent nodes that the target has registered with invoke it
2183 /// The semantics are as follows:
2185 /// SDValue.Val == 0 - No change was made
2186 /// SDValue.Val == N - N was replaced, is dead, and is already handled.
2187 /// otherwise - N should be replaced by the returned Operand.
2189 /// In addition, methods provided by DAGCombinerInfo may be used to perform
2190 /// more complex transformations.
2192 virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
2194 /// Return true if it is profitable to move a following shift through this
2195 // node, adjusting any immediate operands as necessary to preserve semantics.
2196 // This transformation may not be desirable if it disrupts a particularly
2197 // auspicious target-specific tree (e.g. bitfield extraction in AArch64).
2198 // By default, it returns true.
2199 virtual bool isDesirableToCommuteWithShift(const SDNode *N /*Op*/) const {
2203 /// Return true if the target has native support for the specified value type
2204 /// and it is 'desirable' to use the type for the given node type. e.g. On x86
2205 /// i16 is legal, but undesirable since i16 instruction encodings are longer
2206 /// and some i16 instructions are slow.
2207 virtual bool isTypeDesirableForOp(unsigned /*Opc*/, EVT VT) const {
2208 // By default, assume all legal types are desirable.
2209 return isTypeLegal(VT);
2212 /// Return true if it is profitable for dag combiner to transform a floating
2213 /// point op of specified opcode to a equivalent op of an integer
2214 /// type. e.g. f32 load -> i32 load can be profitable on ARM.
2215 virtual bool isDesirableToTransformToIntegerOp(unsigned /*Opc*/,
2220 /// This method query the target whether it is beneficial for dag combiner to
2221 /// promote the specified node. If true, it should return the desired
2222 /// promotion type by reference.
2223 virtual bool IsDesirableToPromoteOp(SDValue /*Op*/, EVT &/*PVT*/) const {
2227 //===--------------------------------------------------------------------===//
2228 // Lowering methods - These methods must be implemented by targets so that
2229 // the SelectionDAGBuilder code knows how to lower these.
2232 /// This hook must be implemented to lower the incoming (formal) arguments,
2233 /// described by the Ins array, into the specified DAG. The implementation
2234 /// should fill in the InVals array with legal-type argument values, and
2235 /// return the resulting token chain value.
2238 LowerFormalArguments(SDValue /*Chain*/, CallingConv::ID /*CallConv*/,
2240 const SmallVectorImpl<ISD::InputArg> &/*Ins*/,
2241 SDLoc /*dl*/, SelectionDAG &/*DAG*/,
2242 SmallVectorImpl<SDValue> &/*InVals*/) const {
2243 llvm_unreachable("Not Implemented");
2246 struct ArgListEntry {
2255 bool isInAlloca : 1;
2256 bool isReturned : 1;
2259 ArgListEntry() : isSExt(false), isZExt(false), isInReg(false),
2260 isSRet(false), isNest(false), isByVal(false), isInAlloca(false),
2261 isReturned(false), Alignment(0) { }
2263 void setAttributes(ImmutableCallSite *CS, unsigned AttrIdx);
2265 typedef std::vector<ArgListEntry> ArgListTy;
2267 /// This structure contains all information that is necessary for lowering
2268 /// calls. It is passed to TLI::LowerCallTo when the SelectionDAG builder
2269 /// needs to lower a call, and targets will see this struct in their LowerCall
2271 struct CallLoweringInfo {
2278 bool DoesNotReturn : 1;
2279 bool IsReturnValueUsed : 1;
2281 // IsTailCall should be modified by implementations of
2282 // TargetLowering::LowerCall that perform tail call conversions.
2285 unsigned NumFixedArgs;
2286 CallingConv::ID CallConv;
2291 ImmutableCallSite *CS;
2292 SmallVector<ISD::OutputArg, 32> Outs;
2293 SmallVector<SDValue, 32> OutVals;
2294 SmallVector<ISD::InputArg, 32> Ins;
2296 CallLoweringInfo(SelectionDAG &DAG)
2297 : RetTy(nullptr), RetSExt(false), RetZExt(false), IsVarArg(false),
2298 IsInReg(false), DoesNotReturn(false), IsReturnValueUsed(true),
2299 IsTailCall(false), NumFixedArgs(-1), CallConv(CallingConv::C),
2300 DAG(DAG), CS(nullptr) {}
2302 CallLoweringInfo &setDebugLoc(SDLoc dl) {
2307 CallLoweringInfo &setChain(SDValue InChain) {
2312 CallLoweringInfo &setCallee(CallingConv::ID CC, Type *ResultType,
2313 SDValue Target, ArgListTy &&ArgsList,
2314 unsigned FixedArgs = -1) {
2319 (FixedArgs == static_cast<unsigned>(-1) ? Args.size() : FixedArgs);
2320 Args = std::move(ArgsList);
2324 CallLoweringInfo &setCallee(Type *ResultType, FunctionType *FTy,
2325 SDValue Target, ArgListTy &&ArgsList,
2326 ImmutableCallSite &Call) {
2329 IsInReg = Call.paramHasAttr(0, Attribute::InReg);
2330 DoesNotReturn = Call.doesNotReturn();
2331 IsVarArg = FTy->isVarArg();
2332 IsReturnValueUsed = !Call.getInstruction()->use_empty();
2333 RetSExt = Call.paramHasAttr(0, Attribute::SExt);
2334 RetZExt = Call.paramHasAttr(0, Attribute::ZExt);
2338 CallConv = Call.getCallingConv();
2339 NumFixedArgs = FTy->getNumParams();
2340 Args = std::move(ArgsList);
2347 CallLoweringInfo &setInRegister(bool Value = true) {
2352 CallLoweringInfo &setNoReturn(bool Value = true) {
2353 DoesNotReturn = Value;
2357 CallLoweringInfo &setVarArg(bool Value = true) {
2362 CallLoweringInfo &setTailCall(bool Value = true) {
2367 CallLoweringInfo &setDiscardResult(bool Value = true) {
2368 IsReturnValueUsed = !Value;
2372 CallLoweringInfo &setSExtResult(bool Value = true) {
2377 CallLoweringInfo &setZExtResult(bool Value = true) {
2382 ArgListTy &getArgs() {
2387 /// This function lowers an abstract call to a function into an actual call.
2388 /// This returns a pair of operands. The first element is the return value
2389 /// for the function (if RetTy is not VoidTy). The second element is the
2390 /// outgoing token chain. It calls LowerCall to do the actual lowering.
2391 std::pair<SDValue, SDValue> LowerCallTo(CallLoweringInfo &CLI) const;
2393 /// This hook must be implemented to lower calls into the the specified
2394 /// DAG. The outgoing arguments to the call are described by the Outs array,
2395 /// and the values to be returned by the call are described by the Ins
2396 /// array. The implementation should fill in the InVals array with legal-type
2397 /// return values from the call, and return the resulting token chain value.
2399 LowerCall(CallLoweringInfo &/*CLI*/,
2400 SmallVectorImpl<SDValue> &/*InVals*/) const {
2401 llvm_unreachable("Not Implemented");
2404 /// Target-specific cleanup for formal ByVal parameters.
2405 virtual void HandleByVal(CCState *, unsigned &, unsigned) const {}
2407 /// This hook should be implemented to check whether the return values
2408 /// described by the Outs array can fit into the return registers. If false
2409 /// is returned, an sret-demotion is performed.
2410 virtual bool CanLowerReturn(CallingConv::ID /*CallConv*/,
2411 MachineFunction &/*MF*/, bool /*isVarArg*/,
2412 const SmallVectorImpl<ISD::OutputArg> &/*Outs*/,
2413 LLVMContext &/*Context*/) const
2415 // Return true by default to get preexisting behavior.
2419 /// This hook must be implemented to lower outgoing return values, described
2420 /// by the Outs array, into the specified DAG. The implementation should
2421 /// return the resulting token chain value.
2423 LowerReturn(SDValue /*Chain*/, CallingConv::ID /*CallConv*/,
2425 const SmallVectorImpl<ISD::OutputArg> &/*Outs*/,
2426 const SmallVectorImpl<SDValue> &/*OutVals*/,
2427 SDLoc /*dl*/, SelectionDAG &/*DAG*/) const {
2428 llvm_unreachable("Not Implemented");
2431 /// Return true if result of the specified node is used by a return node
2432 /// only. It also compute and return the input chain for the tail call.
2434 /// This is used to determine whether it is possible to codegen a libcall as
2435 /// tail call at legalization time.
2436 virtual bool isUsedByReturnOnly(SDNode *, SDValue &/*Chain*/) const {
2440 /// Return true if the target may be able emit the call instruction as a tail
2441 /// call. This is used by optimization passes to determine if it's profitable
2442 /// to duplicate return instructions to enable tailcall optimization.
2443 virtual bool mayBeEmittedAsTailCall(CallInst *) const {
2447 /// Return the builtin name for the __builtin___clear_cache intrinsic
2448 /// Default is to invoke the clear cache library call
2449 virtual const char * getClearCacheBuiltinName() const {
2450 return "__clear_cache";
2453 /// Return the register ID of the name passed in. Used by named register
2454 /// global variables extension. There is no target-independent behaviour
2455 /// so the default action is to bail.
2456 virtual unsigned getRegisterByName(const char* RegName, EVT VT) const {
2457 report_fatal_error("Named registers not implemented for this target");
2460 /// Return the type that should be used to zero or sign extend a
2461 /// zeroext/signext integer argument or return value. FIXME: Most C calling
2462 /// convention requires the return type to be promoted, but this is not true
2463 /// all the time, e.g. i1 on x86-64. It is also not necessary for non-C
2464 /// calling conventions. The frontend should handle this and include all of
2465 /// the necessary information.
2466 virtual EVT getTypeForExtArgOrReturn(LLVMContext &Context, EVT VT,
2467 ISD::NodeType /*ExtendKind*/) const {
2468 EVT MinVT = getRegisterType(Context, MVT::i32);
2469 return VT.bitsLT(MinVT) ? MinVT : VT;
2472 /// For some targets, an LLVM struct type must be broken down into multiple
2473 /// simple types, but the calling convention specifies that the entire struct
2474 /// must be passed in a block of consecutive registers.
2476 functionArgumentNeedsConsecutiveRegisters(Type *Ty, CallingConv::ID CallConv,
2477 bool isVarArg) const {
2481 /// Returns a 0 terminated array of registers that can be safely used as
2482 /// scratch registers.
2483 virtual const MCPhysReg *getScratchRegisters(CallingConv::ID CC) const {
2487 /// This callback is used to prepare for a volatile or atomic load.
2488 /// It takes a chain node as input and returns the chain for the load itself.
2490 /// Having a callback like this is necessary for targets like SystemZ,
2491 /// which allows a CPU to reuse the result of a previous load indefinitely,
2492 /// even if a cache-coherent store is performed by another CPU. The default
2493 /// implementation does nothing.
2494 virtual SDValue prepareVolatileOrAtomicLoad(SDValue Chain, SDLoc DL,
2495 SelectionDAG &DAG) const {
2499 /// This callback is invoked by the type legalizer to legalize nodes with an
2500 /// illegal operand type but legal result types. It replaces the
2501 /// LowerOperation callback in the type Legalizer. The reason we can not do
2502 /// away with LowerOperation entirely is that LegalizeDAG isn't yet ready to
2503 /// use this callback.
2505 /// TODO: Consider merging with ReplaceNodeResults.
2507 /// The target places new result values for the node in Results (their number
2508 /// and types must exactly match those of the original return values of
2509 /// the node), or leaves Results empty, which indicates that the node is not
2510 /// to be custom lowered after all.
2511 /// The default implementation calls LowerOperation.
2512 virtual void LowerOperationWrapper(SDNode *N,
2513 SmallVectorImpl<SDValue> &Results,
2514 SelectionDAG &DAG) const;
2516 /// This callback is invoked for operations that are unsupported by the
2517 /// target, which are registered to use 'custom' lowering, and whose defined
2518 /// values are all legal. If the target has no operations that require custom
2519 /// lowering, it need not implement this. The default implementation of this
2521 virtual SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const;
2523 /// This callback is invoked when a node result type is illegal for the
2524 /// target, and the operation was registered to use 'custom' lowering for that
2525 /// result type. The target places new result values for the node in Results
2526 /// (their number and types must exactly match those of the original return
2527 /// values of the node), or leaves Results empty, which indicates that the
2528 /// node is not to be custom lowered after all.
2530 /// If the target has no operations that require custom lowering, it need not
2531 /// implement this. The default implementation aborts.
2532 virtual void ReplaceNodeResults(SDNode * /*N*/,
2533 SmallVectorImpl<SDValue> &/*Results*/,
2534 SelectionDAG &/*DAG*/) const {
2535 llvm_unreachable("ReplaceNodeResults not implemented for this target!");
2538 /// This method returns the name of a target specific DAG node.
2539 virtual const char *getTargetNodeName(unsigned Opcode) const;
2541 /// This method returns a target specific FastISel object, or null if the
2542 /// target does not support "fast" ISel.
2543 virtual FastISel *createFastISel(FunctionLoweringInfo &,
2544 const TargetLibraryInfo *) const {
2549 bool verifyReturnAddressArgumentIsConstant(SDValue Op,
2550 SelectionDAG &DAG) const;
2552 //===--------------------------------------------------------------------===//
2553 // Inline Asm Support hooks
2556 /// This hook allows the target to expand an inline asm call to be explicit
2557 /// llvm code if it wants to. This is useful for turning simple inline asms
2558 /// into LLVM intrinsics, which gives the compiler more information about the
2559 /// behavior of the code.
2560 virtual bool ExpandInlineAsm(CallInst *) const {
2564 enum ConstraintType {
2565 C_Register, // Constraint represents specific register(s).
2566 C_RegisterClass, // Constraint represents any of register(s) in class.
2567 C_Memory, // Memory constraint.
2568 C_Other, // Something else.
2569 C_Unknown // Unsupported constraint.
2572 enum ConstraintWeight {
2574 CW_Invalid = -1, // No match.
2575 CW_Okay = 0, // Acceptable.
2576 CW_Good = 1, // Good weight.
2577 CW_Better = 2, // Better weight.
2578 CW_Best = 3, // Best weight.
2580 // Well-known weights.
2581 CW_SpecificReg = CW_Okay, // Specific register operands.
2582 CW_Register = CW_Good, // Register operands.
2583 CW_Memory = CW_Better, // Memory operands.
2584 CW_Constant = CW_Best, // Constant operand.
2585 CW_Default = CW_Okay // Default or don't know type.
2588 /// This contains information for each constraint that we are lowering.
2589 struct AsmOperandInfo : public InlineAsm::ConstraintInfo {
2590 /// This contains the actual string for the code, like "m". TargetLowering
2591 /// picks the 'best' code from ConstraintInfo::Codes that most closely
2592 /// matches the operand.
2593 std::string ConstraintCode;
2595 /// Information about the constraint code, e.g. Register, RegisterClass,
2596 /// Memory, Other, Unknown.
2597 TargetLowering::ConstraintType ConstraintType;
2599 /// If this is the result output operand or a clobber, this is null,
2600 /// otherwise it is the incoming operand to the CallInst. This gets
2601 /// modified as the asm is processed.
2602 Value *CallOperandVal;
2604 /// The ValueType for the operand value.
2607 /// Return true of this is an input operand that is a matching constraint
2609 bool isMatchingInputConstraint() const;
2611 /// If this is an input matching constraint, this method returns the output
2612 /// operand it matches.
2613 unsigned getMatchedOperand() const;
2615 /// Copy constructor for copying from a ConstraintInfo.
2616 AsmOperandInfo(InlineAsm::ConstraintInfo Info)
2617 : InlineAsm::ConstraintInfo(std::move(Info)),
2618 ConstraintType(TargetLowering::C_Unknown), CallOperandVal(nullptr),
2619 ConstraintVT(MVT::Other) {}
2622 typedef std::vector<AsmOperandInfo> AsmOperandInfoVector;
2624 /// Split up the constraint string from the inline assembly value into the
2625 /// specific constraints and their prefixes, and also tie in the associated
2626 /// operand values. If this returns an empty vector, and if the constraint
2627 /// string itself isn't empty, there was an error parsing.
2628 virtual AsmOperandInfoVector ParseConstraints(ImmutableCallSite CS) const;
2630 /// Examine constraint type and operand type and determine a weight value.
2631 /// The operand object must already have been set up with the operand type.
2632 virtual ConstraintWeight getMultipleConstraintMatchWeight(
2633 AsmOperandInfo &info, int maIndex) const;
2635 /// Examine constraint string and operand type and determine a weight value.
2636 /// The operand object must already have been set up with the operand type.
2637 virtual ConstraintWeight getSingleConstraintMatchWeight(
2638 AsmOperandInfo &info, const char *constraint) const;
2640 /// Determines the constraint code and constraint type to use for the specific
2641 /// AsmOperandInfo, setting OpInfo.ConstraintCode and OpInfo.ConstraintType.
2642 /// If the actual operand being passed in is available, it can be passed in as
2643 /// Op, otherwise an empty SDValue can be passed.
2644 virtual void ComputeConstraintToUse(AsmOperandInfo &OpInfo,
2646 SelectionDAG *DAG = nullptr) const;
2648 /// Given a constraint, return the type of constraint it is for this target.
2649 virtual ConstraintType getConstraintType(const std::string &Constraint) const;
2651 /// Given a physical register constraint (e.g. {edx}), return the register
2652 /// number and the register class for the register.
2654 /// Given a register class constraint, like 'r', if this corresponds directly
2655 /// to an LLVM register class, return a register of 0 and the register class
2658 /// This should only be used for C_Register constraints. On error, this
2659 /// returns a register number of 0 and a null register class pointer..
2660 virtual std::pair<unsigned, const TargetRegisterClass*>
2661 getRegForInlineAsmConstraint(const std::string &Constraint,
2664 /// Try to replace an X constraint, which matches anything, with another that
2665 /// has more specific requirements based on the type of the corresponding
2666 /// operand. This returns null if there is no replacement to make.
2667 virtual const char *LowerXConstraint(EVT ConstraintVT) const;
2669 /// Lower the specified operand into the Ops vector. If it is invalid, don't
2670 /// add anything to Ops.
2671 virtual void LowerAsmOperandForConstraint(SDValue Op, std::string &Constraint,
2672 std::vector<SDValue> &Ops,
2673 SelectionDAG &DAG) const;
2675 //===--------------------------------------------------------------------===//
2676 // Div utility functions
2678 SDValue BuildExactSDIV(SDValue Op1, SDValue Op2, SDLoc dl,
2679 SelectionDAG &DAG) const;
2680 SDValue BuildSDIV(SDNode *N, const APInt &Divisor, SelectionDAG &DAG,
2681 bool IsAfterLegalization,
2682 std::vector<SDNode *> *Created) const;
2683 SDValue BuildUDIV(SDNode *N, const APInt &Divisor, SelectionDAG &DAG,
2684 bool IsAfterLegalization,
2685 std::vector<SDNode *> *Created) const;
2686 virtual SDValue BuildSDIVPow2(SDNode *N, const APInt &Divisor,
2688 std::vector<SDNode *> *Created) const {
2692 /// Indicate whether this target prefers to combine the given number of FDIVs
2693 /// with the same divisor.
2694 virtual bool combineRepeatedFPDivisors(unsigned NumUsers) const {
2698 /// Hooks for building estimates in place of slower divisions and square
2701 /// Return a reciprocal square root estimate value for the input operand.
2702 /// The RefinementSteps output is the number of Newton-Raphson refinement
2703 /// iterations required to generate a sufficient (though not necessarily
2704 /// IEEE-754 compliant) estimate for the value type.
2705 /// The boolean UseOneConstNR output is used to select a Newton-Raphson
2706 /// algorithm implementation that uses one constant or two constants.
2707 /// A target may choose to implement its own refinement within this function.
2708 /// If that's true, then return '0' as the number of RefinementSteps to avoid
2709 /// any further refinement of the estimate.
2710 /// An empty SDValue return means no estimate sequence can be created.
2711 virtual SDValue getRsqrtEstimate(SDValue Operand,
2712 DAGCombinerInfo &DCI,
2713 unsigned &RefinementSteps,
2714 bool &UseOneConstNR) const {
2718 /// Return a reciprocal estimate value for the input operand.
2719 /// The RefinementSteps output is the number of Newton-Raphson refinement
2720 /// iterations required to generate a sufficient (though not necessarily
2721 /// IEEE-754 compliant) estimate for the value type.
2722 /// A target may choose to implement its own refinement within this function.
2723 /// If that's true, then return '0' as the number of RefinementSteps to avoid
2724 /// any further refinement of the estimate.
2725 /// An empty SDValue return means no estimate sequence can be created.
2726 virtual SDValue getRecipEstimate(SDValue Operand,
2727 DAGCombinerInfo &DCI,
2728 unsigned &RefinementSteps) const {
2732 //===--------------------------------------------------------------------===//
2733 // Legalization utility functions
2736 /// Expand a MUL into two nodes. One that computes the high bits of
2737 /// the result and one that computes the low bits.
2738 /// \param HiLoVT The value type to use for the Lo and Hi nodes.
2739 /// \param LL Low bits of the LHS of the MUL. You can use this parameter
2740 /// if you want to control how low bits are extracted from the LHS.
2741 /// \param LH High bits of the LHS of the MUL. See LL for meaning.
2742 /// \param RL Low bits of the RHS of the MUL. See LL for meaning
2743 /// \param RH High bits of the RHS of the MUL. See LL for meaning.
2744 /// \returns true if the node has been expanded. false if it has not
2745 bool expandMUL(SDNode *N, SDValue &Lo, SDValue &Hi, EVT HiLoVT,
2746 SelectionDAG &DAG, SDValue LL = SDValue(),
2747 SDValue LH = SDValue(), SDValue RL = SDValue(),
2748 SDValue RH = SDValue()) const;
2750 /// Expand float(f32) to SINT(i64) conversion
2751 /// \param N Node to expand
2752 /// \param Result output after conversion
2753 /// \returns True, if the expansion was successful, false otherwise
2754 bool expandFP_TO_SINT(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
2756 //===--------------------------------------------------------------------===//
2757 // Instruction Emitting Hooks
2760 /// This method should be implemented by targets that mark instructions with
2761 /// the 'usesCustomInserter' flag. These instructions are special in various
2762 /// ways, which require special support to insert. The specified MachineInstr
2763 /// is created but not inserted into any basic blocks, and this method is
2764 /// called to expand it into a sequence of instructions, potentially also
2765 /// creating new basic blocks and control flow.
2766 virtual MachineBasicBlock *
2767 EmitInstrWithCustomInserter(MachineInstr *MI, MachineBasicBlock *MBB) const;
2769 /// This method should be implemented by targets that mark instructions with
2770 /// the 'hasPostISelHook' flag. These instructions must be adjusted after
2771 /// instruction selection by target hooks. e.g. To fill in optional defs for
2772 /// ARM 's' setting instructions.
2774 AdjustInstrPostInstrSelection(MachineInstr *MI, SDNode *Node) const;
2776 /// If this function returns true, SelectionDAGBuilder emits a
2777 /// LOAD_STACK_GUARD node when it is lowering Intrinsic::stackprotector.
2778 virtual bool useLoadStackGuardNode() const {
2783 /// Given an LLVM IR type and return type attributes, compute the return value
2784 /// EVTs and flags, and optionally also the offsets, if the return value is
2785 /// being lowered to memory.
2786 void GetReturnInfo(Type* ReturnType, AttributeSet attr,
2787 SmallVectorImpl<ISD::OutputArg> &Outs,
2788 const TargetLowering &TLI);
2790 } // end llvm namespace