1 //===-- llvm/Target/TargetLowering.h - Target Lowering Info -----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file describes how to lower LLVM code to machine code. This has two
13 // 1. Which ValueTypes are natively supported by the target.
14 // 2. Which operations are supported for supported ValueTypes.
15 // 3. Cost thresholds for alternative implementations of certain operations.
17 // In addition it has a few other components, like information about FP
20 //===----------------------------------------------------------------------===//
22 #ifndef LLVM_TARGET_TARGETLOWERING_H
23 #define LLVM_TARGET_TARGETLOWERING_H
25 #include "llvm/CallingConv.h"
26 #include "llvm/InlineAsm.h"
27 #include "llvm/Attributes.h"
28 #include "llvm/ADT/SmallPtrSet.h"
29 #include "llvm/CodeGen/SelectionDAGNodes.h"
30 #include "llvm/CodeGen/RuntimeLibcalls.h"
31 #include "llvm/Support/DebugLoc.h"
32 #include "llvm/Target/TargetCallingConv.h"
33 #include "llvm/Target/TargetMachine.h"
45 class FunctionLoweringInfo;
46 class ImmutableCallSite;
47 class MachineBasicBlock;
48 class MachineFunction;
49 class MachineFrameInfo;
51 class MachineJumpTableInfo;
57 template<typename T> class SmallVectorImpl;
60 class TargetRegisterClass;
61 class TargetLoweringObjectFile;
64 // FIXME: should this be here?
73 TLSModel::Model getTLSModel(const GlobalValue *GV, Reloc::Model reloc);
76 //===----------------------------------------------------------------------===//
77 /// TargetLowering - This class defines information used to lower LLVM code to
78 /// legal SelectionDAG operators that the target instruction selector can accept
81 /// This class also defines callbacks that targets must implement to lower
82 /// target-specific constructs to SelectionDAG operators.
84 class TargetLowering {
85 TargetLowering(const TargetLowering&); // DO NOT IMPLEMENT
86 void operator=(const TargetLowering&); // DO NOT IMPLEMENT
88 /// LegalizeAction - This enum indicates whether operations are valid for a
89 /// target, and if not, what action should be used to make them valid.
91 Legal, // The target natively supports this operation.
92 Promote, // This operation should be executed in a larger type.
93 Expand, // Try to expand this to other ops, otherwise use a libcall.
94 Custom // Use the LowerOperation hook to implement custom lowering.
97 /// LegalizeAction - This enum indicates whether a types are legal for a
98 /// target, and if not, what action should be used to make them valid.
99 enum LegalizeTypeAction {
100 TypeLegal, // The target natively supports this type.
101 TypePromoteInteger, // Replace this integer with a larger one.
102 TypeExpandInteger, // Split this integer into two of half the size.
103 TypeSoftenFloat, // Convert this float to a same size integer type.
104 TypeExpandFloat, // Split this float into two of half the size.
105 TypeScalarizeVector, // Replace this one-element vector with its element.
106 TypeSplitVector, // Split this vector into two of half the size.
107 TypeWidenVector // This vector should be widened into a larger vector.
110 enum BooleanContent { // How the target represents true/false values.
111 UndefinedBooleanContent, // Only bit 0 counts, the rest can hold garbage.
112 ZeroOrOneBooleanContent, // All bits zero except for bit 0.
113 ZeroOrNegativeOneBooleanContent // All bits equal to bit 0.
116 static ISD::NodeType getExtendForContent(BooleanContent Content) {
119 assert(false && "Unknown BooleanContent!");
120 case UndefinedBooleanContent:
121 // Extend by adding rubbish bits.
122 return ISD::ANY_EXTEND;
123 case ZeroOrOneBooleanContent:
124 // Extend by adding zero bits.
125 return ISD::ZERO_EXTEND;
126 case ZeroOrNegativeOneBooleanContent:
127 // Extend by copying the sign bit.
128 return ISD::SIGN_EXTEND;
132 /// NOTE: The constructor takes ownership of TLOF.
133 explicit TargetLowering(const TargetMachine &TM,
134 const TargetLoweringObjectFile *TLOF);
135 virtual ~TargetLowering();
137 const TargetMachine &getTargetMachine() const { return TM; }
138 const TargetData *getTargetData() const { return TD; }
139 const TargetLoweringObjectFile &getObjFileLowering() const { return TLOF; }
141 bool isBigEndian() const { return !IsLittleEndian; }
142 bool isLittleEndian() const { return IsLittleEndian; }
143 MVT getPointerTy() const { return PointerTy; }
144 virtual MVT getShiftAmountTy(EVT LHSTy) const;
146 /// isSelectExpensive - Return true if the select operation is expensive for
148 bool isSelectExpensive() const { return SelectIsExpensive; }
150 /// isIntDivCheap() - Return true if integer divide is usually cheaper than
151 /// a sequence of several shifts, adds, and multiplies for this target.
152 bool isIntDivCheap() const { return IntDivIsCheap; }
154 /// isPow2DivCheap() - Return true if pow2 div is cheaper than a chain of
156 bool isPow2DivCheap() const { return Pow2DivIsCheap; }
158 /// isJumpExpensive() - Return true if Flow Control is an expensive operation
159 /// that should be avoided.
160 bool isJumpExpensive() const { return JumpIsExpensive; }
162 /// getSetCCResultType - Return the ValueType of the result of SETCC
163 /// operations. Also used to obtain the target's preferred type for
164 /// the condition operand of SELECT and BRCOND nodes. In the case of
165 /// BRCOND the argument passed is MVT::Other since there are no other
166 /// operands to get a type hint from.
167 virtual EVT getSetCCResultType(EVT VT) const;
169 /// getCmpLibcallReturnType - Return the ValueType for comparison
170 /// libcalls. Comparions libcalls include floating point comparion calls,
171 /// and Ordered/Unordered check calls on floating point numbers.
173 MVT::SimpleValueType getCmpLibcallReturnType() const;
175 /// getBooleanContents - For targets without i1 registers, this gives the
176 /// nature of the high-bits of boolean values held in types wider than i1.
177 /// "Boolean values" are special true/false values produced by nodes like
178 /// SETCC and consumed (as the condition) by nodes like SELECT and BRCOND.
179 /// Not to be confused with general values promoted from i1.
180 /// Some cpus distinguish between vectors of boolean and scalars; the isVec
181 /// parameter selects between the two kinds. For example on X86 a scalar
182 /// boolean should be zero extended from i1, while the elements of a vector
183 /// of booleans should be sign extended from i1.
184 BooleanContent getBooleanContents(bool isVec) const {
185 return isVec ? BooleanVectorContents : BooleanContents;
188 /// getSchedulingPreference - Return target scheduling preference.
189 Sched::Preference getSchedulingPreference() const {
190 return SchedPreferenceInfo;
193 /// getSchedulingPreference - Some scheduler, e.g. hybrid, can switch to
194 /// different scheduling heuristics for different nodes. This function returns
195 /// the preference (or none) for the given node.
196 virtual Sched::Preference getSchedulingPreference(SDNode *) const {
200 /// getRegClassFor - Return the register class that should be used for the
201 /// specified value type.
202 virtual TargetRegisterClass *getRegClassFor(EVT VT) const {
203 assert(VT.isSimple() && "getRegClassFor called on illegal type!");
204 TargetRegisterClass *RC = RegClassForVT[VT.getSimpleVT().SimpleTy];
205 assert(RC && "This value type is not natively supported!");
209 /// getRepRegClassFor - Return the 'representative' register class for the
210 /// specified value type. The 'representative' register class is the largest
211 /// legal super-reg register class for the register class of the value type.
212 /// For example, on i386 the rep register class for i8, i16, and i32 are GR32;
213 /// while the rep register class is GR64 on x86_64.
214 virtual const TargetRegisterClass *getRepRegClassFor(EVT VT) const {
215 assert(VT.isSimple() && "getRepRegClassFor called on illegal type!");
216 const TargetRegisterClass *RC = RepRegClassForVT[VT.getSimpleVT().SimpleTy];
220 /// getRepRegClassCostFor - Return the cost of the 'representative' register
221 /// class for the specified value type.
222 virtual uint8_t getRepRegClassCostFor(EVT VT) const {
223 assert(VT.isSimple() && "getRepRegClassCostFor called on illegal type!");
224 return RepRegClassCostForVT[VT.getSimpleVT().SimpleTy];
227 /// isTypeLegal - Return true if the target has native support for the
228 /// specified value type. This means that it has a register that directly
229 /// holds it without promotions or expansions.
230 bool isTypeLegal(EVT VT) const {
231 assert(!VT.isSimple() ||
232 (unsigned)VT.getSimpleVT().SimpleTy < array_lengthof(RegClassForVT));
233 return VT.isSimple() && RegClassForVT[VT.getSimpleVT().SimpleTy] != 0;
236 class ValueTypeActionImpl {
237 /// ValueTypeActions - For each value type, keep a LegalizeTypeAction enum
238 /// that indicates how instruction selection should deal with the type.
239 uint8_t ValueTypeActions[MVT::LAST_VALUETYPE];
242 ValueTypeActionImpl() {
243 std::fill(ValueTypeActions, array_endof(ValueTypeActions), 0);
246 LegalizeTypeAction getTypeAction(MVT VT) const {
247 return (LegalizeTypeAction)ValueTypeActions[VT.SimpleTy];
250 void setTypeAction(EVT VT, LegalizeTypeAction Action) {
251 unsigned I = VT.getSimpleVT().SimpleTy;
252 ValueTypeActions[I] = Action;
256 const ValueTypeActionImpl &getValueTypeActions() const {
257 return ValueTypeActions;
260 /// getTypeAction - Return how we should legalize values of this type, either
261 /// it is already legal (return 'Legal') or we need to promote it to a larger
262 /// type (return 'Promote'), or we need to expand it into multiple registers
263 /// of smaller integer type (return 'Expand'). 'Custom' is not an option.
264 LegalizeTypeAction getTypeAction(LLVMContext &Context, EVT VT) const {
265 return getTypeConversion(Context, VT).first;
267 LegalizeTypeAction getTypeAction(MVT VT) const {
268 return ValueTypeActions.getTypeAction(VT);
271 /// getTypeToTransformTo - For types supported by the target, this is an
272 /// identity function. For types that must be promoted to larger types, this
273 /// returns the larger type to promote to. For integer types that are larger
274 /// than the largest integer register, this contains one step in the expansion
275 /// to get to the smaller register. For illegal floating point types, this
276 /// returns the integer type to transform to.
277 EVT getTypeToTransformTo(LLVMContext &Context, EVT VT) const {
278 return getTypeConversion(Context, VT).second;
281 /// getTypeToExpandTo - For types supported by the target, this is an
282 /// identity function. For types that must be expanded (i.e. integer types
283 /// that are larger than the largest integer register or illegal floating
284 /// point types), this returns the largest legal type it will be expanded to.
285 EVT getTypeToExpandTo(LLVMContext &Context, EVT VT) const {
286 assert(!VT.isVector());
288 switch (getTypeAction(Context, VT)) {
291 case TypeExpandInteger:
292 VT = getTypeToTransformTo(Context, VT);
295 assert(false && "Type is not legal nor is it to be expanded!");
302 /// getVectorTypeBreakdown - Vector types are broken down into some number of
303 /// legal first class types. For example, EVT::v8f32 maps to 2 EVT::v4f32
304 /// with Altivec or SSE1, or 8 promoted EVT::f64 values with the X86 FP stack.
305 /// Similarly, EVT::v2i64 turns into 4 EVT::i32 values with both PPC and X86.
307 /// This method returns the number of registers needed, and the VT for each
308 /// register. It also returns the VT and quantity of the intermediate values
309 /// before they are promoted/expanded.
311 unsigned getVectorTypeBreakdown(LLVMContext &Context, EVT VT,
313 unsigned &NumIntermediates,
314 EVT &RegisterVT) const;
316 /// getTgtMemIntrinsic: Given an intrinsic, checks if on the target the
317 /// intrinsic will need to map to a MemIntrinsicNode (touches memory). If
318 /// this is the case, it returns true and store the intrinsic
319 /// information into the IntrinsicInfo that was passed to the function.
320 struct IntrinsicInfo {
321 unsigned opc; // target opcode
322 EVT memVT; // memory VT
323 const Value* ptrVal; // value representing memory location
324 int offset; // offset off of ptrVal
325 unsigned align; // alignment
326 bool vol; // is volatile?
327 bool readMem; // reads memory?
328 bool writeMem; // writes memory?
331 virtual bool getTgtMemIntrinsic(IntrinsicInfo &, const CallInst &,
332 unsigned /*Intrinsic*/) const {
336 /// isFPImmLegal - Returns true if the target can instruction select the
337 /// specified FP immediate natively. If false, the legalizer will materialize
338 /// the FP immediate as a load from a constant pool.
339 virtual bool isFPImmLegal(const APFloat &/*Imm*/, EVT /*VT*/) const {
343 /// isShuffleMaskLegal - Targets can use this to indicate that they only
344 /// support *some* VECTOR_SHUFFLE operations, those with specific masks.
345 /// By default, if a target supports the VECTOR_SHUFFLE node, all mask values
346 /// are assumed to be legal.
347 virtual bool isShuffleMaskLegal(const SmallVectorImpl<int> &/*Mask*/,
352 /// canOpTrap - Returns true if the operation can trap for the value type.
353 /// VT must be a legal type. By default, we optimistically assume most
354 /// operations don't trap except for divide and remainder.
355 virtual bool canOpTrap(unsigned Op, EVT VT) const;
357 /// isVectorClearMaskLegal - Similar to isShuffleMaskLegal. This is
358 /// used by Targets can use this to indicate if there is a suitable
359 /// VECTOR_SHUFFLE that can be used to replace a VAND with a constant
361 virtual bool isVectorClearMaskLegal(const SmallVectorImpl<int> &/*Mask*/,
366 /// getOperationAction - Return how this operation should be treated: either
367 /// it is legal, needs to be promoted to a larger size, needs to be
368 /// expanded to some other code sequence, or the target has a custom expander
370 LegalizeAction getOperationAction(unsigned Op, EVT VT) const {
371 if (VT.isExtended()) return Expand;
372 assert(Op < array_lengthof(OpActions[0]) && "Table isn't big enough!");
373 unsigned I = (unsigned) VT.getSimpleVT().SimpleTy;
374 return (LegalizeAction)OpActions[I][Op];
377 /// isOperationLegalOrCustom - Return true if the specified operation is
378 /// legal on this target or can be made legal with custom lowering. This
379 /// is used to help guide high-level lowering decisions.
380 bool isOperationLegalOrCustom(unsigned Op, EVT VT) const {
381 return (VT == MVT::Other || isTypeLegal(VT)) &&
382 (getOperationAction(Op, VT) == Legal ||
383 getOperationAction(Op, VT) == Custom);
386 /// isOperationLegal - Return true if the specified operation is legal on this
388 bool isOperationLegal(unsigned Op, EVT VT) const {
389 return (VT == MVT::Other || isTypeLegal(VT)) &&
390 getOperationAction(Op, VT) == Legal;
393 /// getLoadExtAction - Return how this load with extension should be treated:
394 /// either it is legal, needs to be promoted to a larger size, needs to be
395 /// expanded to some other code sequence, or the target has a custom expander
397 LegalizeAction getLoadExtAction(unsigned ExtType, EVT VT) const {
398 assert(ExtType < ISD::LAST_LOADEXT_TYPE &&
399 VT.getSimpleVT() < MVT::LAST_VALUETYPE &&
400 "Table isn't big enough!");
401 return (LegalizeAction)LoadExtActions[VT.getSimpleVT().SimpleTy][ExtType];
404 /// isLoadExtLegal - Return true if the specified load with extension is legal
406 bool isLoadExtLegal(unsigned ExtType, EVT VT) const {
407 return VT.isSimple() && getLoadExtAction(ExtType, VT) == Legal;
410 /// getTruncStoreAction - Return how this store with truncation should be
411 /// treated: either it is legal, needs to be promoted to a larger size, needs
412 /// to be expanded to some other code sequence, or the target has a custom
414 LegalizeAction getTruncStoreAction(EVT ValVT, EVT MemVT) const {
415 assert(ValVT.getSimpleVT() < MVT::LAST_VALUETYPE &&
416 MemVT.getSimpleVT() < MVT::LAST_VALUETYPE &&
417 "Table isn't big enough!");
418 return (LegalizeAction)TruncStoreActions[ValVT.getSimpleVT().SimpleTy]
419 [MemVT.getSimpleVT().SimpleTy];
422 /// isTruncStoreLegal - Return true if the specified store with truncation is
423 /// legal on this target.
424 bool isTruncStoreLegal(EVT ValVT, EVT MemVT) const {
425 return isTypeLegal(ValVT) && MemVT.isSimple() &&
426 getTruncStoreAction(ValVT, MemVT) == Legal;
429 /// getIndexedLoadAction - Return how the indexed load should be treated:
430 /// either it is legal, needs to be promoted to a larger size, needs to be
431 /// expanded to some other code sequence, or the target has a custom expander
434 getIndexedLoadAction(unsigned IdxMode, EVT VT) const {
435 assert(IdxMode < ISD::LAST_INDEXED_MODE &&
436 VT.getSimpleVT() < MVT::LAST_VALUETYPE &&
437 "Table isn't big enough!");
438 unsigned Ty = (unsigned)VT.getSimpleVT().SimpleTy;
439 return (LegalizeAction)((IndexedModeActions[Ty][IdxMode] & 0xf0) >> 4);
442 /// isIndexedLoadLegal - Return true if the specified indexed load is legal
444 bool isIndexedLoadLegal(unsigned IdxMode, EVT VT) const {
445 return VT.isSimple() &&
446 (getIndexedLoadAction(IdxMode, VT) == Legal ||
447 getIndexedLoadAction(IdxMode, VT) == Custom);
450 /// getIndexedStoreAction - Return how the indexed store should be treated:
451 /// either it is legal, needs to be promoted to a larger size, needs to be
452 /// expanded to some other code sequence, or the target has a custom expander
455 getIndexedStoreAction(unsigned IdxMode, EVT VT) const {
456 assert(IdxMode < ISD::LAST_INDEXED_MODE &&
457 VT.getSimpleVT() < MVT::LAST_VALUETYPE &&
458 "Table isn't big enough!");
459 unsigned Ty = (unsigned)VT.getSimpleVT().SimpleTy;
460 return (LegalizeAction)(IndexedModeActions[Ty][IdxMode] & 0x0f);
463 /// isIndexedStoreLegal - Return true if the specified indexed load is legal
465 bool isIndexedStoreLegal(unsigned IdxMode, EVT VT) const {
466 return VT.isSimple() &&
467 (getIndexedStoreAction(IdxMode, VT) == Legal ||
468 getIndexedStoreAction(IdxMode, VT) == Custom);
471 /// getCondCodeAction - Return how the condition code should be treated:
472 /// either it is legal, needs to be expanded to some other code sequence,
473 /// or the target has a custom expander for it.
475 getCondCodeAction(ISD::CondCode CC, EVT VT) const {
476 assert((unsigned)CC < array_lengthof(CondCodeActions) &&
477 (unsigned)VT.getSimpleVT().SimpleTy < sizeof(CondCodeActions[0])*4 &&
478 "Table isn't big enough!");
479 LegalizeAction Action = (LegalizeAction)
480 ((CondCodeActions[CC] >> (2*VT.getSimpleVT().SimpleTy)) & 3);
481 assert(Action != Promote && "Can't promote condition code!");
485 /// isCondCodeLegal - Return true if the specified condition code is legal
487 bool isCondCodeLegal(ISD::CondCode CC, EVT VT) const {
488 return getCondCodeAction(CC, VT) == Legal ||
489 getCondCodeAction(CC, VT) == Custom;
493 /// getTypeToPromoteTo - If the action for this operation is to promote, this
494 /// method returns the ValueType to promote to.
495 EVT getTypeToPromoteTo(unsigned Op, EVT VT) const {
496 assert(getOperationAction(Op, VT) == Promote &&
497 "This operation isn't promoted!");
499 // See if this has an explicit type specified.
500 std::map<std::pair<unsigned, MVT::SimpleValueType>,
501 MVT::SimpleValueType>::const_iterator PTTI =
502 PromoteToType.find(std::make_pair(Op, VT.getSimpleVT().SimpleTy));
503 if (PTTI != PromoteToType.end()) return PTTI->second;
505 assert((VT.isInteger() || VT.isFloatingPoint()) &&
506 "Cannot autopromote this type, add it with AddPromotedToType.");
510 NVT = (MVT::SimpleValueType)(NVT.getSimpleVT().SimpleTy+1);
511 assert(NVT.isInteger() == VT.isInteger() && NVT != MVT::isVoid &&
512 "Didn't find type to promote to!");
513 } while (!isTypeLegal(NVT) ||
514 getOperationAction(Op, NVT) == Promote);
518 /// getValueType - Return the EVT corresponding to this LLVM type.
519 /// This is fixed by the LLVM operations except for the pointer size. If
520 /// AllowUnknown is true, this will return MVT::Other for types with no EVT
521 /// counterpart (e.g. structs), otherwise it will assert.
522 EVT getValueType(Type *Ty, bool AllowUnknown = false) const {
523 EVT VT = EVT::getEVT(Ty, AllowUnknown);
524 return VT == MVT::iPTR ? PointerTy : VT;
527 /// getByValTypeAlignment - Return the desired alignment for ByVal aggregate
528 /// function arguments in the caller parameter area. This is the actual
529 /// alignment, not its logarithm.
530 virtual unsigned getByValTypeAlignment(Type *Ty) const;
532 /// getRegisterType - Return the type of registers that this ValueType will
533 /// eventually require.
534 EVT getRegisterType(MVT VT) const {
535 assert((unsigned)VT.SimpleTy < array_lengthof(RegisterTypeForVT));
536 return RegisterTypeForVT[VT.SimpleTy];
539 /// getRegisterType - Return the type of registers that this ValueType will
540 /// eventually require.
541 EVT getRegisterType(LLVMContext &Context, EVT VT) const {
543 assert((unsigned)VT.getSimpleVT().SimpleTy <
544 array_lengthof(RegisterTypeForVT));
545 return RegisterTypeForVT[VT.getSimpleVT().SimpleTy];
549 unsigned NumIntermediates;
550 (void)getVectorTypeBreakdown(Context, VT, VT1,
551 NumIntermediates, RegisterVT);
554 if (VT.isInteger()) {
555 return getRegisterType(Context, getTypeToTransformTo(Context, VT));
557 assert(0 && "Unsupported extended type!");
558 return EVT(MVT::Other); // Not reached
561 /// getNumRegisters - Return the number of registers that this ValueType will
562 /// eventually require. This is one for any types promoted to live in larger
563 /// registers, but may be more than one for types (like i64) that are split
564 /// into pieces. For types like i140, which are first promoted then expanded,
565 /// it is the number of registers needed to hold all the bits of the original
566 /// type. For an i140 on a 32 bit machine this means 5 registers.
567 unsigned getNumRegisters(LLVMContext &Context, EVT VT) const {
569 assert((unsigned)VT.getSimpleVT().SimpleTy <
570 array_lengthof(NumRegistersForVT));
571 return NumRegistersForVT[VT.getSimpleVT().SimpleTy];
575 unsigned NumIntermediates;
576 return getVectorTypeBreakdown(Context, VT, VT1, NumIntermediates, VT2);
578 if (VT.isInteger()) {
579 unsigned BitWidth = VT.getSizeInBits();
580 unsigned RegWidth = getRegisterType(Context, VT).getSizeInBits();
581 return (BitWidth + RegWidth - 1) / RegWidth;
583 assert(0 && "Unsupported extended type!");
584 return 0; // Not reached
587 /// ShouldShrinkFPConstant - If true, then instruction selection should
588 /// seek to shrink the FP constant of the specified type to a smaller type
589 /// in order to save space and / or reduce runtime.
590 virtual bool ShouldShrinkFPConstant(EVT) const { return true; }
592 /// hasTargetDAGCombine - If true, the target has custom DAG combine
593 /// transformations that it can perform for the specified node.
594 bool hasTargetDAGCombine(ISD::NodeType NT) const {
595 assert(unsigned(NT >> 3) < array_lengthof(TargetDAGCombineArray));
596 return TargetDAGCombineArray[NT >> 3] & (1 << (NT&7));
599 /// This function returns the maximum number of store operations permitted
600 /// to replace a call to llvm.memset. The value is set by the target at the
601 /// performance threshold for such a replacement. If OptSize is true,
602 /// return the limit for functions that have OptSize attribute.
603 /// @brief Get maximum # of store operations permitted for llvm.memset
604 unsigned getMaxStoresPerMemset(bool OptSize) const {
605 return OptSize ? maxStoresPerMemsetOptSize : maxStoresPerMemset;
608 /// This function returns the maximum number of store operations permitted
609 /// to replace a call to llvm.memcpy. The value is set by the target at the
610 /// performance threshold for such a replacement. If OptSize is true,
611 /// return the limit for functions that have OptSize attribute.
612 /// @brief Get maximum # of store operations permitted for llvm.memcpy
613 unsigned getMaxStoresPerMemcpy(bool OptSize) const {
614 return OptSize ? maxStoresPerMemcpyOptSize : maxStoresPerMemcpy;
617 /// This function returns the maximum number of store operations permitted
618 /// to replace a call to llvm.memmove. The value is set by the target at the
619 /// performance threshold for such a replacement. If OptSize is true,
620 /// return the limit for functions that have OptSize attribute.
621 /// @brief Get maximum # of store operations permitted for llvm.memmove
622 unsigned getMaxStoresPerMemmove(bool OptSize) const {
623 return OptSize ? maxStoresPerMemmoveOptSize : maxStoresPerMemmove;
626 /// This function returns true if the target allows unaligned memory accesses.
627 /// of the specified type. This is used, for example, in situations where an
628 /// array copy/move/set is converted to a sequence of store operations. It's
629 /// use helps to ensure that such replacements don't generate code that causes
630 /// an alignment error (trap) on the target machine.
631 /// @brief Determine if the target supports unaligned memory accesses.
632 virtual bool allowsUnalignedMemoryAccesses(EVT) const {
636 /// This function returns true if the target would benefit from code placement
638 /// @brief Determine if the target should perform code placement optimization.
639 bool shouldOptimizeCodePlacement() const {
640 return benefitFromCodePlacementOpt;
643 /// getOptimalMemOpType - Returns the target specific optimal type for load
644 /// and store operations as a result of memset, memcpy, and memmove
645 /// lowering. If DstAlign is zero that means it's safe to destination
646 /// alignment can satisfy any constraint. Similarly if SrcAlign is zero it
647 /// means there isn't a need to check it against alignment requirement,
648 /// probably because the source does not need to be loaded. If
649 /// 'NonScalarIntSafe' is true, that means it's safe to return a
650 /// non-scalar-integer type, e.g. empty string source, constant, or loaded
651 /// from memory. 'MemcpyStrSrc' indicates whether the memcpy source is
652 /// constant so it does not need to be loaded.
653 /// It returns EVT::Other if the type should be determined using generic
654 /// target-independent logic.
655 virtual EVT getOptimalMemOpType(uint64_t /*Size*/,
656 unsigned /*DstAlign*/, unsigned /*SrcAlign*/,
657 bool /*NonScalarIntSafe*/,
658 bool /*MemcpyStrSrc*/,
659 MachineFunction &/*MF*/) const {
663 /// usesUnderscoreSetJmp - Determine if we should use _setjmp or setjmp
664 /// to implement llvm.setjmp.
665 bool usesUnderscoreSetJmp() const {
666 return UseUnderscoreSetJmp;
669 /// usesUnderscoreLongJmp - Determine if we should use _longjmp or longjmp
670 /// to implement llvm.longjmp.
671 bool usesUnderscoreLongJmp() const {
672 return UseUnderscoreLongJmp;
675 /// getStackPointerRegisterToSaveRestore - If a physical register, this
676 /// specifies the register that llvm.savestack/llvm.restorestack should save
678 unsigned getStackPointerRegisterToSaveRestore() const {
679 return StackPointerRegisterToSaveRestore;
682 /// getExceptionAddressRegister - If a physical register, this returns
683 /// the register that receives the exception address on entry to a landing
685 unsigned getExceptionAddressRegister() const {
686 return ExceptionPointerRegister;
689 /// getExceptionSelectorRegister - If a physical register, this returns
690 /// the register that receives the exception typeid on entry to a landing
692 unsigned getExceptionSelectorRegister() const {
693 return ExceptionSelectorRegister;
696 /// getJumpBufSize - returns the target's jmp_buf size in bytes (if never
697 /// set, the default is 200)
698 unsigned getJumpBufSize() const {
702 /// getJumpBufAlignment - returns the target's jmp_buf alignment in bytes
703 /// (if never set, the default is 0)
704 unsigned getJumpBufAlignment() const {
705 return JumpBufAlignment;
708 /// getMinStackArgumentAlignment - return the minimum stack alignment of an
710 unsigned getMinStackArgumentAlignment() const {
711 return MinStackArgumentAlignment;
714 /// getMinFunctionAlignment - return the minimum function alignment.
716 unsigned getMinFunctionAlignment() const {
717 return MinFunctionAlignment;
720 /// getPrefFunctionAlignment - return the preferred function alignment.
722 unsigned getPrefFunctionAlignment() const {
723 return PrefFunctionAlignment;
726 /// getPrefLoopAlignment - return the preferred loop alignment.
728 unsigned getPrefLoopAlignment() const {
729 return PrefLoopAlignment;
732 /// getShouldFoldAtomicFences - return whether the combiner should fold
733 /// fence MEMBARRIER instructions into the atomic intrinsic instructions.
735 bool getShouldFoldAtomicFences() const {
736 return ShouldFoldAtomicFences;
739 /// getInsertFencesFor - return whether the DAG builder should automatically
740 /// insert fences and reduce ordering for atomics.
742 bool getInsertFencesForAtomic() const {
743 return InsertFencesForAtomic;
746 /// getPreIndexedAddressParts - returns true by value, base pointer and
747 /// offset pointer and addressing mode by reference if the node's address
748 /// can be legally represented as pre-indexed load / store address.
749 virtual bool getPreIndexedAddressParts(SDNode * /*N*/, SDValue &/*Base*/,
751 ISD::MemIndexedMode &/*AM*/,
752 SelectionDAG &/*DAG*/) const {
756 /// getPostIndexedAddressParts - returns true by value, base pointer and
757 /// offset pointer and addressing mode by reference if this node can be
758 /// combined with a load / store to form a post-indexed load / store.
759 virtual bool getPostIndexedAddressParts(SDNode * /*N*/, SDNode * /*Op*/,
760 SDValue &/*Base*/, SDValue &/*Offset*/,
761 ISD::MemIndexedMode &/*AM*/,
762 SelectionDAG &/*DAG*/) const {
766 /// getJumpTableEncoding - Return the entry encoding for a jump table in the
767 /// current function. The returned value is a member of the
768 /// MachineJumpTableInfo::JTEntryKind enum.
769 virtual unsigned getJumpTableEncoding() const;
771 virtual const MCExpr *
772 LowerCustomJumpTableEntry(const MachineJumpTableInfo * /*MJTI*/,
773 const MachineBasicBlock * /*MBB*/, unsigned /*uid*/,
774 MCContext &/*Ctx*/) const {
775 assert(0 && "Need to implement this hook if target has custom JTIs");
779 /// getPICJumpTableRelocaBase - Returns relocation base for the given PIC
781 virtual SDValue getPICJumpTableRelocBase(SDValue Table,
782 SelectionDAG &DAG) const;
784 /// getPICJumpTableRelocBaseExpr - This returns the relocation base for the
785 /// given PIC jumptable, the same as getPICJumpTableRelocBase, but as an
787 virtual const MCExpr *
788 getPICJumpTableRelocBaseExpr(const MachineFunction *MF,
789 unsigned JTI, MCContext &Ctx) const;
791 /// isOffsetFoldingLegal - Return true if folding a constant offset
792 /// with the given GlobalAddress is legal. It is frequently not legal in
793 /// PIC relocation models.
794 virtual bool isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const;
796 /// getStackCookieLocation - Return true if the target stores stack
797 /// protector cookies at a fixed offset in some non-standard address
798 /// space, and populates the address space and offset as
800 virtual bool getStackCookieLocation(unsigned &/*AddressSpace*/,
801 unsigned &/*Offset*/) const {
805 /// getMaximalGlobalOffset - Returns the maximal possible offset which can be
806 /// used for loads / stores from the global.
807 virtual unsigned getMaximalGlobalOffset() const {
811 //===--------------------------------------------------------------------===//
812 // TargetLowering Optimization Methods
815 /// TargetLoweringOpt - A convenience struct that encapsulates a DAG, and two
816 /// SDValues for returning information from TargetLowering to its clients
817 /// that want to combine
818 struct TargetLoweringOpt {
825 explicit TargetLoweringOpt(SelectionDAG &InDAG,
827 DAG(InDAG), LegalTys(LT), LegalOps(LO) {}
829 bool LegalTypes() const { return LegalTys; }
830 bool LegalOperations() const { return LegalOps; }
832 bool CombineTo(SDValue O, SDValue N) {
838 /// ShrinkDemandedConstant - Check to see if the specified operand of the
839 /// specified instruction is a constant integer. If so, check to see if
840 /// there are any bits set in the constant that are not demanded. If so,
841 /// shrink the constant and return true.
842 bool ShrinkDemandedConstant(SDValue Op, const APInt &Demanded);
844 /// ShrinkDemandedOp - Convert x+y to (VT)((SmallVT)x+(SmallVT)y) if the
845 /// casts are free. This uses isZExtFree and ZERO_EXTEND for the widening
846 /// cast, but it could be generalized for targets with other types of
847 /// implicit widening casts.
848 bool ShrinkDemandedOp(SDValue Op, unsigned BitWidth, const APInt &Demanded,
852 /// SimplifyDemandedBits - Look at Op. At this point, we know that only the
853 /// DemandedMask bits of the result of Op are ever used downstream. If we can
854 /// use this information to simplify Op, create a new simplified DAG node and
855 /// return true, returning the original and new nodes in Old and New.
856 /// Otherwise, analyze the expression and return a mask of KnownOne and
857 /// KnownZero bits for the expression (used to simplify the caller).
858 /// The KnownZero/One bits may only be accurate for those bits in the
860 bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedMask,
861 APInt &KnownZero, APInt &KnownOne,
862 TargetLoweringOpt &TLO, unsigned Depth = 0) const;
864 /// computeMaskedBitsForTargetNode - Determine which of the bits specified in
865 /// Mask are known to be either zero or one and return them in the
866 /// KnownZero/KnownOne bitsets.
867 virtual void computeMaskedBitsForTargetNode(const SDValue Op,
871 const SelectionDAG &DAG,
872 unsigned Depth = 0) const;
874 /// ComputeNumSignBitsForTargetNode - This method can be implemented by
875 /// targets that want to expose additional information about sign bits to the
877 virtual unsigned ComputeNumSignBitsForTargetNode(SDValue Op,
878 unsigned Depth = 0) const;
880 struct DAGCombinerInfo {
881 void *DC; // The DAG Combiner object.
883 bool BeforeLegalizeOps;
884 bool CalledByLegalizer;
888 DAGCombinerInfo(SelectionDAG &dag, bool bl, bool blo, bool cl, void *dc)
889 : DC(dc), BeforeLegalize(bl), BeforeLegalizeOps(blo),
890 CalledByLegalizer(cl), DAG(dag) {}
892 bool isBeforeLegalize() const { return BeforeLegalize; }
893 bool isBeforeLegalizeOps() const { return BeforeLegalizeOps; }
894 bool isCalledByLegalizer() const { return CalledByLegalizer; }
896 void AddToWorklist(SDNode *N);
897 void RemoveFromWorklist(SDNode *N);
898 SDValue CombineTo(SDNode *N, const std::vector<SDValue> &To,
900 SDValue CombineTo(SDNode *N, SDValue Res, bool AddTo = true);
901 SDValue CombineTo(SDNode *N, SDValue Res0, SDValue Res1, bool AddTo = true);
903 void CommitTargetLoweringOpt(const TargetLoweringOpt &TLO);
906 /// SimplifySetCC - Try to simplify a setcc built with the specified operands
907 /// and cc. If it is unable to simplify it, return a null SDValue.
908 SDValue SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
909 ISD::CondCode Cond, bool foldBooleans,
910 DAGCombinerInfo &DCI, DebugLoc dl) const;
912 /// isGAPlusOffset - Returns true (and the GlobalValue and the offset) if the
913 /// node is a GlobalAddress + offset.
915 isGAPlusOffset(SDNode *N, const GlobalValue* &GA, int64_t &Offset) const;
917 /// PerformDAGCombine - This method will be invoked for all target nodes and
918 /// for any target-independent nodes that the target has registered with
921 /// The semantics are as follows:
923 /// SDValue.Val == 0 - No change was made
924 /// SDValue.Val == N - N was replaced, is dead, and is already handled.
925 /// otherwise - N should be replaced by the returned Operand.
927 /// In addition, methods provided by DAGCombinerInfo may be used to perform
928 /// more complex transformations.
930 virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
932 /// isTypeDesirableForOp - Return true if the target has native support for
933 /// the specified value type and it is 'desirable' to use the type for the
934 /// given node type. e.g. On x86 i16 is legal, but undesirable since i16
935 /// instruction encodings are longer and some i16 instructions are slow.
936 virtual bool isTypeDesirableForOp(unsigned /*Opc*/, EVT VT) const {
937 // By default, assume all legal types are desirable.
938 return isTypeLegal(VT);
941 /// isDesirableToPromoteOp - Return true if it is profitable for dag combiner
942 /// to transform a floating point op of specified opcode to a equivalent op of
943 /// an integer type. e.g. f32 load -> i32 load can be profitable on ARM.
944 virtual bool isDesirableToTransformToIntegerOp(unsigned /*Opc*/,
949 /// IsDesirableToPromoteOp - This method query the target whether it is
950 /// beneficial for dag combiner to promote the specified node. If true, it
951 /// should return the desired promotion type by reference.
952 virtual bool IsDesirableToPromoteOp(SDValue /*Op*/, EVT &/*PVT*/) const {
956 //===--------------------------------------------------------------------===//
957 // TargetLowering Configuration Methods - These methods should be invoked by
958 // the derived class constructor to configure this object for the target.
962 /// setBooleanContents - Specify how the target extends the result of a
963 /// boolean value from i1 to a wider type. See getBooleanContents.
964 void setBooleanContents(BooleanContent Ty) { BooleanContents = Ty; }
965 /// setBooleanVectorContents - Specify how the target extends the result
966 /// of a vector boolean value from a vector of i1 to a wider type. See
967 /// getBooleanContents.
968 void setBooleanVectorContents(BooleanContent Ty) {
969 BooleanVectorContents = Ty;
972 /// setSchedulingPreference - Specify the target scheduling preference.
973 void setSchedulingPreference(Sched::Preference Pref) {
974 SchedPreferenceInfo = Pref;
977 /// setUseUnderscoreSetJmp - Indicate whether this target prefers to
978 /// use _setjmp to implement llvm.setjmp or the non _ version.
979 /// Defaults to false.
980 void setUseUnderscoreSetJmp(bool Val) {
981 UseUnderscoreSetJmp = Val;
984 /// setUseUnderscoreLongJmp - Indicate whether this target prefers to
985 /// use _longjmp to implement llvm.longjmp or the non _ version.
986 /// Defaults to false.
987 void setUseUnderscoreLongJmp(bool Val) {
988 UseUnderscoreLongJmp = Val;
991 /// setStackPointerRegisterToSaveRestore - If set to a physical register, this
992 /// specifies the register that llvm.savestack/llvm.restorestack should save
994 void setStackPointerRegisterToSaveRestore(unsigned R) {
995 StackPointerRegisterToSaveRestore = R;
998 /// setExceptionPointerRegister - If set to a physical register, this sets
999 /// the register that receives the exception address on entry to a landing
1001 void setExceptionPointerRegister(unsigned R) {
1002 ExceptionPointerRegister = R;
1005 /// setExceptionSelectorRegister - If set to a physical register, this sets
1006 /// the register that receives the exception typeid on entry to a landing
1008 void setExceptionSelectorRegister(unsigned R) {
1009 ExceptionSelectorRegister = R;
1012 /// SelectIsExpensive - Tells the code generator not to expand operations
1013 /// into sequences that use the select operations if possible.
1014 void setSelectIsExpensive(bool isExpensive = true) {
1015 SelectIsExpensive = isExpensive;
1018 /// JumpIsExpensive - Tells the code generator not to expand sequence of
1019 /// operations into a separate sequences that increases the amount of
1021 void setJumpIsExpensive(bool isExpensive = true) {
1022 JumpIsExpensive = isExpensive;
1025 /// setIntDivIsCheap - Tells the code generator that integer divide is
1026 /// expensive, and if possible, should be replaced by an alternate sequence
1027 /// of instructions not containing an integer divide.
1028 void setIntDivIsCheap(bool isCheap = true) { IntDivIsCheap = isCheap; }
1030 /// setPow2DivIsCheap - Tells the code generator that it shouldn't generate
1031 /// srl/add/sra for a signed divide by power of two, and let the target handle
1033 void setPow2DivIsCheap(bool isCheap = true) { Pow2DivIsCheap = isCheap; }
1035 /// addRegisterClass - Add the specified register class as an available
1036 /// regclass for the specified value type. This indicates the selector can
1037 /// handle values of that class natively.
1038 void addRegisterClass(EVT VT, TargetRegisterClass *RC) {
1039 assert((unsigned)VT.getSimpleVT().SimpleTy < array_lengthof(RegClassForVT));
1040 AvailableRegClasses.push_back(std::make_pair(VT, RC));
1041 RegClassForVT[VT.getSimpleVT().SimpleTy] = RC;
1044 /// findRepresentativeClass - Return the largest legal super-reg register class
1045 /// of the register class for the specified type and its associated "cost".
1046 virtual std::pair<const TargetRegisterClass*, uint8_t>
1047 findRepresentativeClass(EVT VT) const;
1049 /// computeRegisterProperties - Once all of the register classes are added,
1050 /// this allows us to compute derived properties we expose.
1051 void computeRegisterProperties();
1053 /// setOperationAction - Indicate that the specified operation does not work
1054 /// with the specified type and indicate what to do about it.
1055 void setOperationAction(unsigned Op, MVT VT,
1056 LegalizeAction Action) {
1057 assert(Op < array_lengthof(OpActions[0]) && "Table isn't big enough!");
1058 OpActions[(unsigned)VT.SimpleTy][Op] = (uint8_t)Action;
1061 /// setLoadExtAction - Indicate that the specified load with extension does
1062 /// not work with the specified type and indicate what to do about it.
1063 void setLoadExtAction(unsigned ExtType, MVT VT,
1064 LegalizeAction Action) {
1065 assert(ExtType < ISD::LAST_LOADEXT_TYPE && VT < MVT::LAST_VALUETYPE &&
1066 "Table isn't big enough!");
1067 LoadExtActions[VT.SimpleTy][ExtType] = (uint8_t)Action;
1070 /// setTruncStoreAction - Indicate that the specified truncating store does
1071 /// not work with the specified type and indicate what to do about it.
1072 void setTruncStoreAction(MVT ValVT, MVT MemVT,
1073 LegalizeAction Action) {
1074 assert(ValVT < MVT::LAST_VALUETYPE && MemVT < MVT::LAST_VALUETYPE &&
1075 "Table isn't big enough!");
1076 TruncStoreActions[ValVT.SimpleTy][MemVT.SimpleTy] = (uint8_t)Action;
1079 /// setIndexedLoadAction - Indicate that the specified indexed load does or
1080 /// does not work with the specified type and indicate what to do abort
1081 /// it. NOTE: All indexed mode loads are initialized to Expand in
1082 /// TargetLowering.cpp
1083 void setIndexedLoadAction(unsigned IdxMode, MVT VT,
1084 LegalizeAction Action) {
1085 assert(VT < MVT::LAST_VALUETYPE && IdxMode < ISD::LAST_INDEXED_MODE &&
1086 (unsigned)Action < 0xf && "Table isn't big enough!");
1087 // Load action are kept in the upper half.
1088 IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0xf0;
1089 IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] |= ((uint8_t)Action) <<4;
1092 /// setIndexedStoreAction - Indicate that the specified indexed store does or
1093 /// does not work with the specified type and indicate what to do about
1094 /// it. NOTE: All indexed mode stores are initialized to Expand in
1095 /// TargetLowering.cpp
1096 void setIndexedStoreAction(unsigned IdxMode, MVT VT,
1097 LegalizeAction Action) {
1098 assert(VT < MVT::LAST_VALUETYPE && IdxMode < ISD::LAST_INDEXED_MODE &&
1099 (unsigned)Action < 0xf && "Table isn't big enough!");
1100 // Store action are kept in the lower half.
1101 IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0x0f;
1102 IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] |= ((uint8_t)Action);
1105 /// setCondCodeAction - Indicate that the specified condition code is or isn't
1106 /// supported on the target and indicate what to do about it.
1107 void setCondCodeAction(ISD::CondCode CC, MVT VT,
1108 LegalizeAction Action) {
1109 assert(VT < MVT::LAST_VALUETYPE &&
1110 (unsigned)CC < array_lengthof(CondCodeActions) &&
1111 "Table isn't big enough!");
1112 CondCodeActions[(unsigned)CC] &= ~(uint64_t(3UL) << VT.SimpleTy*2);
1113 CondCodeActions[(unsigned)CC] |= (uint64_t)Action << VT.SimpleTy*2;
1116 /// AddPromotedToType - If Opc/OrigVT is specified as being promoted, the
1117 /// promotion code defaults to trying a larger integer/fp until it can find
1118 /// one that works. If that default is insufficient, this method can be used
1119 /// by the target to override the default.
1120 void AddPromotedToType(unsigned Opc, MVT OrigVT, MVT DestVT) {
1121 PromoteToType[std::make_pair(Opc, OrigVT.SimpleTy)] = DestVT.SimpleTy;
1124 /// setTargetDAGCombine - Targets should invoke this method for each target
1125 /// independent node that they want to provide a custom DAG combiner for by
1126 /// implementing the PerformDAGCombine virtual method.
1127 void setTargetDAGCombine(ISD::NodeType NT) {
1128 assert(unsigned(NT >> 3) < array_lengthof(TargetDAGCombineArray));
1129 TargetDAGCombineArray[NT >> 3] |= 1 << (NT&7);
1132 /// setJumpBufSize - Set the target's required jmp_buf buffer size (in
1133 /// bytes); default is 200
1134 void setJumpBufSize(unsigned Size) {
1138 /// setJumpBufAlignment - Set the target's required jmp_buf buffer
1139 /// alignment (in bytes); default is 0
1140 void setJumpBufAlignment(unsigned Align) {
1141 JumpBufAlignment = Align;
1144 /// setMinFunctionAlignment - Set the target's minimum function alignment (in
1146 void setMinFunctionAlignment(unsigned Align) {
1147 MinFunctionAlignment = Align;
1150 /// setPrefFunctionAlignment - Set the target's preferred function alignment.
1151 /// This should be set if there is a performance benefit to
1152 /// higher-than-minimum alignment (in log2(bytes))
1153 void setPrefFunctionAlignment(unsigned Align) {
1154 PrefFunctionAlignment = Align;
1157 /// setPrefLoopAlignment - Set the target's preferred loop alignment. Default
1158 /// alignment is zero, it means the target does not care about loop alignment.
1159 /// The alignment is specified in log2(bytes).
1160 void setPrefLoopAlignment(unsigned Align) {
1161 PrefLoopAlignment = Align;
1164 /// setMinStackArgumentAlignment - Set the minimum stack alignment of an
1165 /// argument (in log2(bytes)).
1166 void setMinStackArgumentAlignment(unsigned Align) {
1167 MinStackArgumentAlignment = Align;
1170 /// setShouldFoldAtomicFences - Set if the target's implementation of the
1171 /// atomic operation intrinsics includes locking. Default is false.
1172 void setShouldFoldAtomicFences(bool fold) {
1173 ShouldFoldAtomicFences = fold;
1176 /// setInsertFencesForAtomic - Set if the the DAG builder should
1177 /// automatically insert fences and reduce the order of atomic memory
1178 /// operations to Monotonic.
1179 void setInsertFencesForAtomic(bool fence) {
1180 InsertFencesForAtomic = fence;
1184 //===--------------------------------------------------------------------===//
1185 // Lowering methods - These methods must be implemented by targets so that
1186 // the SelectionDAGLowering code knows how to lower these.
1189 /// LowerFormalArguments - This hook must be implemented to lower the
1190 /// incoming (formal) arguments, described by the Ins array, into the
1191 /// specified DAG. The implementation should fill in the InVals array
1192 /// with legal-type argument values, and return the resulting token
1196 LowerFormalArguments(SDValue /*Chain*/, CallingConv::ID /*CallConv*/,
1198 const SmallVectorImpl<ISD::InputArg> &/*Ins*/,
1199 DebugLoc /*dl*/, SelectionDAG &/*DAG*/,
1200 SmallVectorImpl<SDValue> &/*InVals*/) const {
1201 assert(0 && "Not Implemented");
1202 return SDValue(); // this is here to silence compiler errors
1205 /// LowerCallTo - This function lowers an abstract call to a function into an
1206 /// actual call. This returns a pair of operands. The first element is the
1207 /// return value for the function (if RetTy is not VoidTy). The second
1208 /// element is the outgoing token chain. It calls LowerCall to do the actual
1210 struct ArgListEntry {
1221 ArgListEntry() : isSExt(false), isZExt(false), isInReg(false),
1222 isSRet(false), isNest(false), isByVal(false), Alignment(0) { }
1224 typedef std::vector<ArgListEntry> ArgListTy;
1225 std::pair<SDValue, SDValue>
1226 LowerCallTo(SDValue Chain, Type *RetTy, bool RetSExt, bool RetZExt,
1227 bool isVarArg, bool isInreg, unsigned NumFixedArgs,
1228 CallingConv::ID CallConv, bool isTailCall,
1229 bool isReturnValueUsed, SDValue Callee, ArgListTy &Args,
1230 SelectionDAG &DAG, DebugLoc dl) const;
1232 /// LowerCall - This hook must be implemented to lower calls into the
1233 /// the specified DAG. The outgoing arguments to the call are described
1234 /// by the Outs array, and the values to be returned by the call are
1235 /// described by the Ins array. The implementation should fill in the
1236 /// InVals array with legal-type return values from the call, and return
1237 /// the resulting token chain value.
1239 LowerCall(SDValue /*Chain*/, SDValue /*Callee*/,
1240 CallingConv::ID /*CallConv*/, bool /*isVarArg*/,
1241 bool &/*isTailCall*/,
1242 const SmallVectorImpl<ISD::OutputArg> &/*Outs*/,
1243 const SmallVectorImpl<SDValue> &/*OutVals*/,
1244 const SmallVectorImpl<ISD::InputArg> &/*Ins*/,
1245 DebugLoc /*dl*/, SelectionDAG &/*DAG*/,
1246 SmallVectorImpl<SDValue> &/*InVals*/) const {
1247 assert(0 && "Not Implemented");
1248 return SDValue(); // this is here to silence compiler errors
1251 /// HandleByVal - Target-specific cleanup for formal ByVal parameters.
1252 virtual void HandleByVal(CCState *, unsigned &) const {}
1254 /// CanLowerReturn - This hook should be implemented to check whether the
1255 /// return values described by the Outs array can fit into the return
1256 /// registers. If false is returned, an sret-demotion is performed.
1258 virtual bool CanLowerReturn(CallingConv::ID /*CallConv*/,
1259 MachineFunction &/*MF*/, bool /*isVarArg*/,
1260 const SmallVectorImpl<ISD::OutputArg> &/*Outs*/,
1261 LLVMContext &/*Context*/) const
1263 // Return true by default to get preexisting behavior.
1267 /// LowerReturn - This hook must be implemented to lower outgoing
1268 /// return values, described by the Outs array, into the specified
1269 /// DAG. The implementation should return the resulting token chain
1273 LowerReturn(SDValue /*Chain*/, CallingConv::ID /*CallConv*/,
1275 const SmallVectorImpl<ISD::OutputArg> &/*Outs*/,
1276 const SmallVectorImpl<SDValue> &/*OutVals*/,
1277 DebugLoc /*dl*/, SelectionDAG &/*DAG*/) const {
1278 assert(0 && "Not Implemented");
1279 return SDValue(); // this is here to silence compiler errors
1282 /// isUsedByReturnOnly - Return true if result of the specified node is used
1283 /// by a return node only. This is used to determine whether it is possible
1284 /// to codegen a libcall as tail call at legalization time.
1285 virtual bool isUsedByReturnOnly(SDNode *) const {
1289 /// mayBeEmittedAsTailCall - Return true if the target may be able emit the
1290 /// call instruction as a tail call. This is used by optimization passes to
1291 /// determine if it's profitable to duplicate return instructions to enable
1292 /// tailcall optimization.
1293 virtual bool mayBeEmittedAsTailCall(CallInst *) const {
1297 /// getTypeForExtArgOrReturn - Return the type that should be used to zero or
1298 /// sign extend a zeroext/signext integer argument or return value.
1299 /// FIXME: Most C calling convention requires the return type to be promoted,
1300 /// but this is not true all the time, e.g. i1 on x86-64. It is also not
1301 /// necessary for non-C calling conventions. The frontend should handle this
1302 /// and include all of the necessary information.
1303 virtual EVT getTypeForExtArgOrReturn(LLVMContext &Context, EVT VT,
1304 ISD::NodeType /*ExtendKind*/) const {
1305 EVT MinVT = getRegisterType(Context, MVT::i32);
1306 return VT.bitsLT(MinVT) ? MinVT : VT;
1309 /// LowerOperationWrapper - This callback is invoked by the type legalizer
1310 /// to legalize nodes with an illegal operand type but legal result types.
1311 /// It replaces the LowerOperation callback in the type Legalizer.
1312 /// The reason we can not do away with LowerOperation entirely is that
1313 /// LegalizeDAG isn't yet ready to use this callback.
1314 /// TODO: Consider merging with ReplaceNodeResults.
1316 /// The target places new result values for the node in Results (their number
1317 /// and types must exactly match those of the original return values of
1318 /// the node), or leaves Results empty, which indicates that the node is not
1319 /// to be custom lowered after all.
1320 /// The default implementation calls LowerOperation.
1321 virtual void LowerOperationWrapper(SDNode *N,
1322 SmallVectorImpl<SDValue> &Results,
1323 SelectionDAG &DAG) const;
1325 /// LowerOperation - This callback is invoked for operations that are
1326 /// unsupported by the target, which are registered to use 'custom' lowering,
1327 /// and whose defined values are all legal.
1328 /// If the target has no operations that require custom lowering, it need not
1329 /// implement this. The default implementation of this aborts.
1330 virtual SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const;
1332 /// ReplaceNodeResults - This callback is invoked when a node result type is
1333 /// illegal for the target, and the operation was registered to use 'custom'
1334 /// lowering for that result type. The target places new result values for
1335 /// the node in Results (their number and types must exactly match those of
1336 /// the original return values of the node), or leaves Results empty, which
1337 /// indicates that the node is not to be custom lowered after all.
1339 /// If the target has no operations that require custom lowering, it need not
1340 /// implement this. The default implementation aborts.
1341 virtual void ReplaceNodeResults(SDNode * /*N*/,
1342 SmallVectorImpl<SDValue> &/*Results*/,
1343 SelectionDAG &/*DAG*/) const {
1344 assert(0 && "ReplaceNodeResults not implemented for this target!");
1347 /// getTargetNodeName() - This method returns the name of a target specific
1349 virtual const char *getTargetNodeName(unsigned Opcode) const;
1351 /// createFastISel - This method returns a target specific FastISel object,
1352 /// or null if the target does not support "fast" ISel.
1353 virtual FastISel *createFastISel(FunctionLoweringInfo &) const {
1357 //===--------------------------------------------------------------------===//
1358 // Inline Asm Support hooks
1361 /// ExpandInlineAsm - This hook allows the target to expand an inline asm
1362 /// call to be explicit llvm code if it wants to. This is useful for
1363 /// turning simple inline asms into LLVM intrinsics, which gives the
1364 /// compiler more information about the behavior of the code.
1365 virtual bool ExpandInlineAsm(CallInst *) const {
1369 enum ConstraintType {
1370 C_Register, // Constraint represents specific register(s).
1371 C_RegisterClass, // Constraint represents any of register(s) in class.
1372 C_Memory, // Memory constraint.
1373 C_Other, // Something else.
1374 C_Unknown // Unsupported constraint.
1377 enum ConstraintWeight {
1379 CW_Invalid = -1, // No match.
1380 CW_Okay = 0, // Acceptable.
1381 CW_Good = 1, // Good weight.
1382 CW_Better = 2, // Better weight.
1383 CW_Best = 3, // Best weight.
1385 // Well-known weights.
1386 CW_SpecificReg = CW_Okay, // Specific register operands.
1387 CW_Register = CW_Good, // Register operands.
1388 CW_Memory = CW_Better, // Memory operands.
1389 CW_Constant = CW_Best, // Constant operand.
1390 CW_Default = CW_Okay // Default or don't know type.
1393 /// AsmOperandInfo - This contains information for each constraint that we are
1395 struct AsmOperandInfo : public InlineAsm::ConstraintInfo {
1396 /// ConstraintCode - This contains the actual string for the code, like "m".
1397 /// TargetLowering picks the 'best' code from ConstraintInfo::Codes that
1398 /// most closely matches the operand.
1399 std::string ConstraintCode;
1401 /// ConstraintType - Information about the constraint code, e.g. Register,
1402 /// RegisterClass, Memory, Other, Unknown.
1403 TargetLowering::ConstraintType ConstraintType;
1405 /// CallOperandval - If this is the result output operand or a
1406 /// clobber, this is null, otherwise it is the incoming operand to the
1407 /// CallInst. This gets modified as the asm is processed.
1408 Value *CallOperandVal;
1410 /// ConstraintVT - The ValueType for the operand value.
1413 /// isMatchingInputConstraint - Return true of this is an input operand that
1414 /// is a matching constraint like "4".
1415 bool isMatchingInputConstraint() const;
1417 /// getMatchedOperand - If this is an input matching constraint, this method
1418 /// returns the output operand it matches.
1419 unsigned getMatchedOperand() const;
1421 /// Copy constructor for copying from an AsmOperandInfo.
1422 AsmOperandInfo(const AsmOperandInfo &info)
1423 : InlineAsm::ConstraintInfo(info),
1424 ConstraintCode(info.ConstraintCode),
1425 ConstraintType(info.ConstraintType),
1426 CallOperandVal(info.CallOperandVal),
1427 ConstraintVT(info.ConstraintVT) {
1430 /// Copy constructor for copying from a ConstraintInfo.
1431 AsmOperandInfo(const InlineAsm::ConstraintInfo &info)
1432 : InlineAsm::ConstraintInfo(info),
1433 ConstraintType(TargetLowering::C_Unknown),
1434 CallOperandVal(0), ConstraintVT(MVT::Other) {
1438 typedef std::vector<AsmOperandInfo> AsmOperandInfoVector;
1440 /// ParseConstraints - Split up the constraint string from the inline
1441 /// assembly value into the specific constraints and their prefixes,
1442 /// and also tie in the associated operand values.
1443 /// If this returns an empty vector, and if the constraint string itself
1444 /// isn't empty, there was an error parsing.
1445 virtual AsmOperandInfoVector ParseConstraints(ImmutableCallSite CS) const;
1447 /// Examine constraint type and operand type and determine a weight value.
1448 /// The operand object must already have been set up with the operand type.
1449 virtual ConstraintWeight getMultipleConstraintMatchWeight(
1450 AsmOperandInfo &info, int maIndex) const;
1452 /// Examine constraint string and operand type and determine a weight value.
1453 /// The operand object must already have been set up with the operand type.
1454 virtual ConstraintWeight getSingleConstraintMatchWeight(
1455 AsmOperandInfo &info, const char *constraint) const;
1457 /// ComputeConstraintToUse - Determines the constraint code and constraint
1458 /// type to use for the specific AsmOperandInfo, setting
1459 /// OpInfo.ConstraintCode and OpInfo.ConstraintType. If the actual operand
1460 /// being passed in is available, it can be passed in as Op, otherwise an
1461 /// empty SDValue can be passed.
1462 virtual void ComputeConstraintToUse(AsmOperandInfo &OpInfo,
1464 SelectionDAG *DAG = 0) const;
1466 /// getConstraintType - Given a constraint, return the type of constraint it
1467 /// is for this target.
1468 virtual ConstraintType getConstraintType(const std::string &Constraint) const;
1470 /// getRegForInlineAsmConstraint - Given a physical register constraint (e.g.
1471 /// {edx}), return the register number and the register class for the
1474 /// Given a register class constraint, like 'r', if this corresponds directly
1475 /// to an LLVM register class, return a register of 0 and the register class
1478 /// This should only be used for C_Register constraints. On error,
1479 /// this returns a register number of 0 and a null register class pointer..
1480 virtual std::pair<unsigned, const TargetRegisterClass*>
1481 getRegForInlineAsmConstraint(const std::string &Constraint,
1484 /// LowerXConstraint - try to replace an X constraint, which matches anything,
1485 /// with another that has more specific requirements based on the type of the
1486 /// corresponding operand. This returns null if there is no replacement to
1488 virtual const char *LowerXConstraint(EVT ConstraintVT) const;
1490 /// LowerAsmOperandForConstraint - Lower the specified operand into the Ops
1491 /// vector. If it is invalid, don't add anything to Ops.
1492 virtual void LowerAsmOperandForConstraint(SDValue Op, std::string &Constraint,
1493 std::vector<SDValue> &Ops,
1494 SelectionDAG &DAG) const;
1496 //===--------------------------------------------------------------------===//
1497 // Instruction Emitting Hooks
1500 // EmitInstrWithCustomInserter - This method should be implemented by targets
1501 // that mark instructions with the 'usesCustomInserter' flag. These
1502 // instructions are special in various ways, which require special support to
1503 // insert. The specified MachineInstr is created but not inserted into any
1504 // basic blocks, and this method is called to expand it into a sequence of
1505 // instructions, potentially also creating new basic blocks and control flow.
1506 virtual MachineBasicBlock *
1507 EmitInstrWithCustomInserter(MachineInstr *MI, MachineBasicBlock *MBB) const;
1509 /// AdjustInstrPostInstrSelection - This method should be implemented by
1510 /// targets that mark instructions with the 'hasPostISelHook' flag. These
1511 /// instructions must be adjusted after instruction selection by target hooks.
1512 /// e.g. To fill in optional defs for ARM 's' setting instructions.
1514 AdjustInstrPostInstrSelection(MachineInstr *MI, SDNode *Node) const;
1516 //===--------------------------------------------------------------------===//
1517 // Addressing mode description hooks (used by LSR etc).
1520 /// AddrMode - This represents an addressing mode of:
1521 /// BaseGV + BaseOffs + BaseReg + Scale*ScaleReg
1522 /// If BaseGV is null, there is no BaseGV.
1523 /// If BaseOffs is zero, there is no base offset.
1524 /// If HasBaseReg is false, there is no base register.
1525 /// If Scale is zero, there is no ScaleReg. Scale of 1 indicates a reg with
1529 GlobalValue *BaseGV;
1533 AddrMode() : BaseGV(0), BaseOffs(0), HasBaseReg(false), Scale(0) {}
1536 /// isLegalAddressingMode - Return true if the addressing mode represented by
1537 /// AM is legal for this target, for a load/store of the specified type.
1538 /// The type may be VoidTy, in which case only return true if the addressing
1539 /// mode is legal for a load/store of any legal type.
1540 /// TODO: Handle pre/postinc as well.
1541 virtual bool isLegalAddressingMode(const AddrMode &AM, Type *Ty) const;
1543 /// isLegalICmpImmediate - Return true if the specified immediate is legal
1544 /// icmp immediate, that is the target has icmp instructions which can compare
1545 /// a register against the immediate without having to materialize the
1546 /// immediate into a register.
1547 virtual bool isLegalICmpImmediate(int64_t) const {
1551 /// isLegalAddImmediate - Return true if the specified immediate is legal
1552 /// add immediate, that is the target has add instructions which can add
1553 /// a register with the immediate without having to materialize the
1554 /// immediate into a register.
1555 virtual bool isLegalAddImmediate(int64_t) const {
1559 /// isTruncateFree - Return true if it's free to truncate a value of
1560 /// type Ty1 to type Ty2. e.g. On x86 it's free to truncate a i32 value in
1561 /// register EAX to i16 by referencing its sub-register AX.
1562 virtual bool isTruncateFree(Type * /*Ty1*/, Type * /*Ty2*/) const {
1566 virtual bool isTruncateFree(EVT /*VT1*/, EVT /*VT2*/) const {
1570 /// isZExtFree - Return true if any actual instruction that defines a
1571 /// value of type Ty1 implicitly zero-extends the value to Ty2 in the result
1572 /// register. This does not necessarily include registers defined in
1573 /// unknown ways, such as incoming arguments, or copies from unknown
1574 /// virtual registers. Also, if isTruncateFree(Ty2, Ty1) is true, this
1575 /// does not necessarily apply to truncate instructions. e.g. on x86-64,
1576 /// all instructions that define 32-bit values implicit zero-extend the
1577 /// result out to 64 bits.
1578 virtual bool isZExtFree(Type * /*Ty1*/, Type * /*Ty2*/) const {
1582 virtual bool isZExtFree(EVT /*VT1*/, EVT /*VT2*/) const {
1586 /// isNarrowingProfitable - Return true if it's profitable to narrow
1587 /// operations of type VT1 to VT2. e.g. on x86, it's profitable to narrow
1588 /// from i32 to i8 but not from i32 to i16.
1589 virtual bool isNarrowingProfitable(EVT /*VT1*/, EVT /*VT2*/) const {
1593 //===--------------------------------------------------------------------===//
1594 // Div utility functions
1596 SDValue BuildExactSDIV(SDValue Op1, SDValue Op2, DebugLoc dl,
1597 SelectionDAG &DAG) const;
1598 SDValue BuildSDIV(SDNode *N, SelectionDAG &DAG,
1599 std::vector<SDNode*>* Created) const;
1600 SDValue BuildUDIV(SDNode *N, SelectionDAG &DAG,
1601 std::vector<SDNode*>* Created) const;
1604 //===--------------------------------------------------------------------===//
1605 // Runtime Library hooks
1608 /// setLibcallName - Rename the default libcall routine name for the specified
1610 void setLibcallName(RTLIB::Libcall Call, const char *Name) {
1611 LibcallRoutineNames[Call] = Name;
1614 /// getLibcallName - Get the libcall routine name for the specified libcall.
1616 const char *getLibcallName(RTLIB::Libcall Call) const {
1617 return LibcallRoutineNames[Call];
1620 /// setCmpLibcallCC - Override the default CondCode to be used to test the
1621 /// result of the comparison libcall against zero.
1622 void setCmpLibcallCC(RTLIB::Libcall Call, ISD::CondCode CC) {
1623 CmpLibcallCCs[Call] = CC;
1626 /// getCmpLibcallCC - Get the CondCode that's to be used to test the result of
1627 /// the comparison libcall against zero.
1628 ISD::CondCode getCmpLibcallCC(RTLIB::Libcall Call) const {
1629 return CmpLibcallCCs[Call];
1632 /// setLibcallCallingConv - Set the CallingConv that should be used for the
1633 /// specified libcall.
1634 void setLibcallCallingConv(RTLIB::Libcall Call, CallingConv::ID CC) {
1635 LibcallCallingConvs[Call] = CC;
1638 /// getLibcallCallingConv - Get the CallingConv that should be used for the
1639 /// specified libcall.
1640 CallingConv::ID getLibcallCallingConv(RTLIB::Libcall Call) const {
1641 return LibcallCallingConvs[Call];
1645 const TargetMachine &TM;
1646 const TargetData *TD;
1647 const TargetLoweringObjectFile &TLOF;
1649 /// We are in the process of implementing a new TypeLegalization action
1650 /// which is the promotion of vector elements. This feature is under
1651 /// development. Until this feature is complete, it is only enabled using a
1652 /// flag. We pass this flag using a member because of circular dep issues.
1653 /// This member will be removed with the flag once we complete the transition.
1654 bool mayPromoteElements;
1656 /// PointerTy - The type to use for pointers, usually i32 or i64.
1660 /// IsLittleEndian - True if this is a little endian target.
1662 bool IsLittleEndian;
1664 /// SelectIsExpensive - Tells the code generator not to expand operations
1665 /// into sequences that use the select operations if possible.
1666 bool SelectIsExpensive;
1668 /// IntDivIsCheap - Tells the code generator not to expand integer divides by
1669 /// constants into a sequence of muls, adds, and shifts. This is a hack until
1670 /// a real cost model is in place. If we ever optimize for size, this will be
1671 /// set to true unconditionally.
1674 /// Pow2DivIsCheap - Tells the code generator that it shouldn't generate
1675 /// srl/add/sra for a signed divide by power of two, and let the target handle
1677 bool Pow2DivIsCheap;
1679 /// JumpIsExpensive - Tells the code generator that it shouldn't generate
1680 /// extra flow control instructions and should attempt to combine flow
1681 /// control instructions via predication.
1682 bool JumpIsExpensive;
1684 /// UseUnderscoreSetJmp - This target prefers to use _setjmp to implement
1685 /// llvm.setjmp. Defaults to false.
1686 bool UseUnderscoreSetJmp;
1688 /// UseUnderscoreLongJmp - This target prefers to use _longjmp to implement
1689 /// llvm.longjmp. Defaults to false.
1690 bool UseUnderscoreLongJmp;
1692 /// BooleanContents - Information about the contents of the high-bits in
1693 /// boolean values held in a type wider than i1. See getBooleanContents.
1694 BooleanContent BooleanContents;
1695 /// BooleanVectorContents - Information about the contents of the high-bits
1696 /// in boolean vector values when the element type is wider than i1. See
1697 /// getBooleanContents.
1698 BooleanContent BooleanVectorContents;
1700 /// SchedPreferenceInfo - The target scheduling preference: shortest possible
1701 /// total cycles or lowest register usage.
1702 Sched::Preference SchedPreferenceInfo;
1704 /// JumpBufSize - The size, in bytes, of the target's jmp_buf buffers
1705 unsigned JumpBufSize;
1707 /// JumpBufAlignment - The alignment, in bytes, of the target's jmp_buf
1709 unsigned JumpBufAlignment;
1711 /// MinStackArgumentAlignment - The minimum alignment that any argument
1712 /// on the stack needs to have.
1714 unsigned MinStackArgumentAlignment;
1716 /// MinFunctionAlignment - The minimum function alignment (used when
1717 /// optimizing for size, and to prevent explicitly provided alignment
1718 /// from leading to incorrect code).
1720 unsigned MinFunctionAlignment;
1722 /// PrefFunctionAlignment - The preferred function alignment (used when
1723 /// alignment unspecified and optimizing for speed).
1725 unsigned PrefFunctionAlignment;
1727 /// PrefLoopAlignment - The preferred loop alignment.
1729 unsigned PrefLoopAlignment;
1731 /// ShouldFoldAtomicFences - Whether fencing MEMBARRIER instructions should
1732 /// be folded into the enclosed atomic intrinsic instruction by the
1734 bool ShouldFoldAtomicFences;
1736 /// InsertFencesForAtomic - Whether the DAG builder should automatically
1737 /// insert fences and reduce ordering for atomics. (This will be set for
1738 /// for most architectures with weak memory ordering.)
1739 bool InsertFencesForAtomic;
1741 /// StackPointerRegisterToSaveRestore - If set to a physical register, this
1742 /// specifies the register that llvm.savestack/llvm.restorestack should save
1744 unsigned StackPointerRegisterToSaveRestore;
1746 /// ExceptionPointerRegister - If set to a physical register, this specifies
1747 /// the register that receives the exception address on entry to a landing
1749 unsigned ExceptionPointerRegister;
1751 /// ExceptionSelectorRegister - If set to a physical register, this specifies
1752 /// the register that receives the exception typeid on entry to a landing
1754 unsigned ExceptionSelectorRegister;
1756 /// RegClassForVT - This indicates the default register class to use for
1757 /// each ValueType the target supports natively.
1758 TargetRegisterClass *RegClassForVT[MVT::LAST_VALUETYPE];
1759 unsigned char NumRegistersForVT[MVT::LAST_VALUETYPE];
1760 EVT RegisterTypeForVT[MVT::LAST_VALUETYPE];
1762 /// RepRegClassForVT - This indicates the "representative" register class to
1763 /// use for each ValueType the target supports natively. This information is
1764 /// used by the scheduler to track register pressure. By default, the
1765 /// representative register class is the largest legal super-reg register
1766 /// class of the register class of the specified type. e.g. On x86, i8, i16,
1767 /// and i32's representative class would be GR32.
1768 const TargetRegisterClass *RepRegClassForVT[MVT::LAST_VALUETYPE];
1770 /// RepRegClassCostForVT - This indicates the "cost" of the "representative"
1771 /// register class for each ValueType. The cost is used by the scheduler to
1772 /// approximate register pressure.
1773 uint8_t RepRegClassCostForVT[MVT::LAST_VALUETYPE];
1775 /// TransformToType - For any value types we are promoting or expanding, this
1776 /// contains the value type that we are changing to. For Expanded types, this
1777 /// contains one step of the expand (e.g. i64 -> i32), even if there are
1778 /// multiple steps required (e.g. i64 -> i16). For types natively supported
1779 /// by the system, this holds the same type (e.g. i32 -> i32).
1780 EVT TransformToType[MVT::LAST_VALUETYPE];
1782 /// OpActions - For each operation and each value type, keep a LegalizeAction
1783 /// that indicates how instruction selection should deal with the operation.
1784 /// Most operations are Legal (aka, supported natively by the target), but
1785 /// operations that are not should be described. Note that operations on
1786 /// non-legal value types are not described here.
1787 uint8_t OpActions[MVT::LAST_VALUETYPE][ISD::BUILTIN_OP_END];
1789 /// LoadExtActions - For each load extension type and each value type,
1790 /// keep a LegalizeAction that indicates how instruction selection should deal
1791 /// with a load of a specific value type and extension type.
1792 uint8_t LoadExtActions[MVT::LAST_VALUETYPE][ISD::LAST_LOADEXT_TYPE];
1794 /// TruncStoreActions - For each value type pair keep a LegalizeAction that
1795 /// indicates whether a truncating store of a specific value type and
1796 /// truncating type is legal.
1797 uint8_t TruncStoreActions[MVT::LAST_VALUETYPE][MVT::LAST_VALUETYPE];
1799 /// IndexedModeActions - For each indexed mode and each value type,
1800 /// keep a pair of LegalizeAction that indicates how instruction
1801 /// selection should deal with the load / store. The first dimension is the
1802 /// value_type for the reference. The second dimension represents the various
1803 /// modes for load store.
1804 uint8_t IndexedModeActions[MVT::LAST_VALUETYPE][ISD::LAST_INDEXED_MODE];
1806 /// CondCodeActions - For each condition code (ISD::CondCode) keep a
1807 /// LegalizeAction that indicates how instruction selection should
1808 /// deal with the condition code.
1809 uint64_t CondCodeActions[ISD::SETCC_INVALID];
1811 ValueTypeActionImpl ValueTypeActions;
1813 typedef std::pair<LegalizeTypeAction, EVT> LegalizeKind;
1816 getTypeConversion(LLVMContext &Context, EVT VT) const {
1817 // If this is a simple type, use the ComputeRegisterProp mechanism.
1818 if (VT.isSimple()) {
1819 assert((unsigned)VT.getSimpleVT().SimpleTy <
1820 array_lengthof(TransformToType));
1821 EVT NVT = TransformToType[VT.getSimpleVT().SimpleTy];
1822 LegalizeTypeAction LA = ValueTypeActions.getTypeAction(VT.getSimpleVT());
1825 (!(NVT.isSimple() && LA != TypeLegal) ||
1826 ValueTypeActions.getTypeAction(NVT.getSimpleVT()) != TypePromoteInteger)
1827 && "Promote may not follow Expand or Promote");
1829 return LegalizeKind(LA, NVT);
1832 // Handle Extended Scalar Types.
1833 if (!VT.isVector()) {
1834 assert(VT.isInteger() && "Float types must be simple");
1835 unsigned BitSize = VT.getSizeInBits();
1836 // First promote to a power-of-two size, then expand if necessary.
1837 if (BitSize < 8 || !isPowerOf2_32(BitSize)) {
1838 EVT NVT = VT.getRoundIntegerType(Context);
1839 assert(NVT != VT && "Unable to round integer VT");
1840 LegalizeKind NextStep = getTypeConversion(Context, NVT);
1841 // Avoid multi-step promotion.
1842 if (NextStep.first == TypePromoteInteger) return NextStep;
1843 // Return rounded integer type.
1844 return LegalizeKind(TypePromoteInteger, NVT);
1847 return LegalizeKind(TypeExpandInteger,
1848 EVT::getIntegerVT(Context, VT.getSizeInBits()/2));
1851 // Handle vector types.
1852 unsigned NumElts = VT.getVectorNumElements();
1853 EVT EltVT = VT.getVectorElementType();
1855 // Vectors with only one element are always scalarized.
1857 return LegalizeKind(TypeScalarizeVector, EltVT);
1859 // If we allow the promotion of vector elements using a flag,
1860 // then try to widen vector elements until a legal type is found.
1861 if (mayPromoteElements && EltVT.isInteger()) {
1862 // Vectors with a number of elements that is not a power of two are always
1863 // widened, for example <3 x float> -> <4 x float>.
1864 if (!VT.isPow2VectorType()) {
1865 NumElts = (unsigned)NextPowerOf2(NumElts);
1866 EVT NVT = EVT::getVectorVT(Context, EltVT, NumElts);
1867 return LegalizeKind(TypeWidenVector, NVT);
1870 // Examine the element type.
1871 LegalizeKind LK = getTypeConversion(Context, EltVT);
1873 // If type is to be expanded, split the vector.
1874 // <4 x i140> -> <2 x i140>
1875 if (LK.first == TypeExpandInteger)
1876 return LegalizeKind(TypeSplitVector,
1877 EVT::getVectorVT(Context, EltVT, NumElts / 2));
1879 // Promote the integer element types until a legal vector type is found
1880 // or until the element integer type is too big. If a legal type was not
1881 // found, fallback to the usual mechanism of widening/splitting the
1884 // Increase the bitwidth of the element to the next pow-of-two
1885 // (which is greater than 8 bits).
1886 EltVT = EVT::getIntegerVT(Context, 1 + EltVT.getSizeInBits()
1887 ).getRoundIntegerType(Context);
1889 // Stop trying when getting a non-simple element type.
1890 // Note that vector elements may be greater than legal vector element
1891 // types. Example: X86 XMM registers hold 64bit element on 32bit systems.
1892 if (!EltVT.isSimple()) break;
1894 // Build a new vector type and check if it is legal.
1895 MVT NVT = MVT::getVectorVT(EltVT.getSimpleVT(), NumElts);
1896 // Found a legal promoted vector type.
1897 if (NVT != MVT() && ValueTypeActions.getTypeAction(NVT) == TypeLegal)
1898 return LegalizeKind(TypePromoteInteger,
1899 EVT::getVectorVT(Context, EltVT, NumElts));
1903 // Try to widen the vector until a legal type is found.
1904 // If there is no wider legal type, split the vector.
1906 // Round up to the next power of 2.
1907 NumElts = (unsigned)NextPowerOf2(NumElts);
1909 // If there is no simple vector type with this many elements then there
1910 // cannot be a larger legal vector type. Note that this assumes that
1911 // there are no skipped intermediate vector types in the simple types.
1912 if (!EltVT.isSimple()) break;
1913 MVT LargerVector = MVT::getVectorVT(EltVT.getSimpleVT(), NumElts);
1914 if (LargerVector == MVT()) break;
1916 // If this type is legal then widen the vector.
1917 if (ValueTypeActions.getTypeAction(LargerVector) == TypeLegal)
1918 return LegalizeKind(TypeWidenVector, LargerVector);
1921 // Widen odd vectors to next power of two.
1922 if (!VT.isPow2VectorType()) {
1923 EVT NVT = VT.getPow2VectorType(Context);
1924 return LegalizeKind(TypeWidenVector, NVT);
1927 // Vectors with illegal element types are expanded.
1928 EVT NVT = EVT::getVectorVT(Context, EltVT, VT.getVectorNumElements() / 2);
1929 return LegalizeKind(TypeSplitVector, NVT);
1931 assert(false && "Unable to handle this kind of vector type");
1932 return LegalizeKind(TypeLegal, VT);
1935 std::vector<std::pair<EVT, TargetRegisterClass*> > AvailableRegClasses;
1937 /// TargetDAGCombineArray - Targets can specify ISD nodes that they would
1938 /// like PerformDAGCombine callbacks for by calling setTargetDAGCombine(),
1939 /// which sets a bit in this array.
1941 TargetDAGCombineArray[(ISD::BUILTIN_OP_END+CHAR_BIT-1)/CHAR_BIT];
1943 /// PromoteToType - For operations that must be promoted to a specific type,
1944 /// this holds the destination type. This map should be sparse, so don't hold
1947 /// Targets add entries to this map with AddPromotedToType(..), clients access
1948 /// this with getTypeToPromoteTo(..).
1949 std::map<std::pair<unsigned, MVT::SimpleValueType>, MVT::SimpleValueType>
1952 /// LibcallRoutineNames - Stores the name each libcall.
1954 const char *LibcallRoutineNames[RTLIB::UNKNOWN_LIBCALL];
1956 /// CmpLibcallCCs - The ISD::CondCode that should be used to test the result
1957 /// of each of the comparison libcall against zero.
1958 ISD::CondCode CmpLibcallCCs[RTLIB::UNKNOWN_LIBCALL];
1960 /// LibcallCallingConvs - Stores the CallingConv that should be used for each
1962 CallingConv::ID LibcallCallingConvs[RTLIB::UNKNOWN_LIBCALL];
1965 /// When lowering \@llvm.memset this field specifies the maximum number of
1966 /// store operations that may be substituted for the call to memset. Targets
1967 /// must set this value based on the cost threshold for that target. Targets
1968 /// should assume that the memset will be done using as many of the largest
1969 /// store operations first, followed by smaller ones, if necessary, per
1970 /// alignment restrictions. For example, storing 9 bytes on a 32-bit machine
1971 /// with 16-bit alignment would result in four 2-byte stores and one 1-byte
1972 /// store. This only applies to setting a constant array of a constant size.
1973 /// @brief Specify maximum number of store instructions per memset call.
1974 unsigned maxStoresPerMemset;
1976 /// Maximum number of stores operations that may be substituted for the call
1977 /// to memset, used for functions with OptSize attribute.
1978 unsigned maxStoresPerMemsetOptSize;
1980 /// When lowering \@llvm.memcpy this field specifies the maximum number of
1981 /// store operations that may be substituted for a call to memcpy. Targets
1982 /// must set this value based on the cost threshold for that target. Targets
1983 /// should assume that the memcpy will be done using as many of the largest
1984 /// store operations first, followed by smaller ones, if necessary, per
1985 /// alignment restrictions. For example, storing 7 bytes on a 32-bit machine
1986 /// with 32-bit alignment would result in one 4-byte store, a one 2-byte store
1987 /// and one 1-byte store. This only applies to copying a constant array of
1989 /// @brief Specify maximum bytes of store instructions per memcpy call.
1990 unsigned maxStoresPerMemcpy;
1992 /// Maximum number of store operations that may be substituted for a call
1993 /// to memcpy, used for functions with OptSize attribute.
1994 unsigned maxStoresPerMemcpyOptSize;
1996 /// When lowering \@llvm.memmove this field specifies the maximum number of
1997 /// store instructions that may be substituted for a call to memmove. Targets
1998 /// must set this value based on the cost threshold for that target. Targets
1999 /// should assume that the memmove will be done using as many of the largest
2000 /// store operations first, followed by smaller ones, if necessary, per
2001 /// alignment restrictions. For example, moving 9 bytes on a 32-bit machine
2002 /// with 8-bit alignment would result in nine 1-byte stores. This only
2003 /// applies to copying a constant array of constant size.
2004 /// @brief Specify maximum bytes of store instructions per memmove call.
2005 unsigned maxStoresPerMemmove;
2007 /// Maximum number of store instructions that may be substituted for a call
2008 /// to memmove, used for functions with OpSize attribute.
2009 unsigned maxStoresPerMemmoveOptSize;
2011 /// This field specifies whether the target can benefit from code placement
2013 bool benefitFromCodePlacementOpt;
2016 /// isLegalRC - Return true if the value types that can be represented by the
2017 /// specified register class are all legal.
2018 bool isLegalRC(const TargetRegisterClass *RC) const;
2020 /// hasLegalSuperRegRegClasses - Return true if the specified register class
2021 /// has one or more super-reg register classes that are legal.
2022 bool hasLegalSuperRegRegClasses(const TargetRegisterClass *RC) const;
2025 /// GetReturnInfo - Given an LLVM IR type and return type attributes,
2026 /// compute the return value EVTs and flags, and optionally also
2027 /// the offsets, if the return value is being lowered to memory.
2028 void GetReturnInfo(Type* ReturnType, Attributes attr,
2029 SmallVectorImpl<ISD::OutputArg> &Outs,
2030 const TargetLowering &TLI,
2031 SmallVectorImpl<uint64_t> *Offsets = 0);
2033 } // end llvm namespace