BasicTargetTransformInfo.cpp revision 69e42dbd006c0afb732067ece7327988b1e24c01 
1//===- BasicTargetTransformInfo.cpp - Basic target-independent TTI impl ---===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9/// \file
10/// This file provides the implementation of a basic TargetTransformInfo pass
11/// predicated on the target abstractions present in the target independent
12/// code generator. It uses these (primarily TargetLowering) to model as much
13/// of the TTI query interface as possible. It is included by most targets so
14/// that they can specialize only a small subset of the query space.
15///
16//===----------------------------------------------------------------------===//
17
18#define DEBUG_TYPE "basictti"
19#include "llvm/CodeGen/Passes.h"
20#include "llvm/Analysis/TargetTransformInfo.h"
21#include "llvm/Target/TargetLowering.h"
22#include <utility>
23
24using namespace llvm;
25
26namespace {
27
28class BasicTTI : public ImmutablePass, public TargetTransformInfo {
29  const TargetLoweringBase *TLI;
30
31  /// Estimate the overhead of scalarizing an instruction. Insert and Extract
32  /// are set if the result needs to be inserted and/or extracted from vectors.
33  unsigned getScalarizationOverhead(Type *Ty, bool Insert, bool Extract) const;
34
35public:
36  BasicTTI() : ImmutablePass(ID), TLI(0) {
37    llvm_unreachable("This pass cannot be directly constructed");
38  }
39
40  BasicTTI(const TargetLoweringBase *TLI) : ImmutablePass(ID), TLI(TLI) {
41    initializeBasicTTIPass(*PassRegistry::getPassRegistry());
42  }
43
44  virtual void initializePass() {
45    pushTTIStack(this);
46  }
47
48  virtual void finalizePass() {
49    popTTIStack();
50  }
51
52  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
53    TargetTransformInfo::getAnalysisUsage(AU);
54  }
55
56  /// Pass identification.
57  static char ID;
58
59  /// Provide necessary pointer adjustments for the two base classes.
60  virtual void *getAdjustedAnalysisPointer(const void *ID) {
61    if (ID == &TargetTransformInfo::ID)
62      return (TargetTransformInfo*)this;
63    return this;
64  }
65
66  /// \name Scalar TTI Implementations
67  /// @{
68
69  virtual bool isLegalAddImmediate(int64_t imm) const;
70  virtual bool isLegalICmpImmediate(int64_t imm) const;
71  virtual bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV,
72                                     int64_t BaseOffset, bool HasBaseReg,
73                                     int64_t Scale) const;
74  virtual bool isTruncateFree(Type *Ty1, Type *Ty2) const;
75  virtual bool isTypeLegal(Type *Ty) const;
76  virtual unsigned getJumpBufAlignment() const;
77  virtual unsigned getJumpBufSize() const;
78  virtual bool shouldBuildLookupTables() const;
79
80  /// @}
81
82  /// \name Vector TTI Implementations
83  /// @{
84
85  virtual unsigned getNumberOfRegisters(bool Vector) const;
86  virtual unsigned getMaximumUnrollFactor() const;
87  virtual unsigned getRegisterBitWidth(bool Vector) const;
88  virtual unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty) const;
89  virtual unsigned getShuffleCost(ShuffleKind Kind, Type *Tp,
90                                  int Index, Type *SubTp) const;
91  virtual unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
92                                    Type *Src) const;
93  virtual unsigned getCFInstrCost(unsigned Opcode) const;
94  virtual unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
95                                      Type *CondTy) const;
96  virtual unsigned getVectorInstrCost(unsigned Opcode, Type *Val,
97                                      unsigned Index) const;
98  virtual unsigned getMemoryOpCost(unsigned Opcode, Type *Src,
99                                   unsigned Alignment,
100                                   unsigned AddressSpace) const;
101  virtual unsigned getIntrinsicInstrCost(Intrinsic::ID, Type *RetTy,
102                                         ArrayRef<Type*> Tys) const;
103  virtual unsigned getNumberOfParts(Type *Tp) const;
104
105  /// @}
106};
107
108}
109
110INITIALIZE_AG_PASS(BasicTTI, TargetTransformInfo, "basictti",
111                   "Target independent code generator's TTI", true, true, false)
112char BasicTTI::ID = 0;
113
114ImmutablePass *
115llvm::createBasicTargetTransformInfoPass(const TargetLoweringBase *TLI) {
116  return new BasicTTI(TLI);
117}
118
119
120bool BasicTTI::isLegalAddImmediate(int64_t imm) const {
121  return TLI->isLegalAddImmediate(imm);
122}
123
124bool BasicTTI::isLegalICmpImmediate(int64_t imm) const {
125  return TLI->isLegalICmpImmediate(imm);
126}
127
128bool BasicTTI::isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV,
129                                     int64_t BaseOffset, bool HasBaseReg,
130                                     int64_t Scale) const {
131  TargetLoweringBase::AddrMode AM;
132  AM.BaseGV = BaseGV;
133  AM.BaseOffs = BaseOffset;
134  AM.HasBaseReg = HasBaseReg;
135  AM.Scale = Scale;
136  return TLI->isLegalAddressingMode(AM, Ty);
137}
138
139bool BasicTTI::isTruncateFree(Type *Ty1, Type *Ty2) const {
140  return TLI->isTruncateFree(Ty1, Ty2);
141}
142
143bool BasicTTI::isTypeLegal(Type *Ty) const {
144  EVT T = TLI->getValueType(Ty);
145  return TLI->isTypeLegal(T);
146}
147
148unsigned BasicTTI::getJumpBufAlignment() const {
149  return TLI->getJumpBufAlignment();
150}
151
152unsigned BasicTTI::getJumpBufSize() const {
153  return TLI->getJumpBufSize();
154}
155
156bool BasicTTI::shouldBuildLookupTables() const {
157  return TLI->supportJumpTables() &&
158      (TLI->isOperationLegalOrCustom(ISD::BR_JT, MVT::Other) ||
159       TLI->isOperationLegalOrCustom(ISD::BRIND, MVT::Other));
160}
161
162//===----------------------------------------------------------------------===//
163//
164// Calls used by the vectorizers.
165//
166//===----------------------------------------------------------------------===//
167
168unsigned BasicTTI::getScalarizationOverhead(Type *Ty, bool Insert,
169                                            bool Extract) const {
170  assert (Ty->isVectorTy() && "Can only scalarize vectors");
171  unsigned Cost = 0;
172
173  for (int i = 0, e = Ty->getVectorNumElements(); i < e; ++i) {
174    if (Insert)
175      Cost += TopTTI->getVectorInstrCost(Instruction::InsertElement, Ty, i);
176    if (Extract)
177      Cost += TopTTI->getVectorInstrCost(Instruction::ExtractElement, Ty, i);
178  }
179
180  return Cost;
181}
182
183unsigned BasicTTI::getNumberOfRegisters(bool Vector) const {
184  return 1;
185}
186
187unsigned BasicTTI::getRegisterBitWidth(bool Vector) const {
188  return 32;
189}
190
191unsigned BasicTTI::getMaximumUnrollFactor() const {
192  return 1;
193}
194
195unsigned BasicTTI::getArithmeticInstrCost(unsigned Opcode, Type *Ty) const {
196  // Check if any of the operands are vector operands.
197  int ISD = TLI->InstructionOpcodeToISD(Opcode);
198  assert(ISD && "Invalid opcode");
199
200  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Ty);
201
202  if (TLI->isOperationLegalOrPromote(ISD, LT.second)) {
203    // The operation is legal. Assume it costs 1.
204    // If the type is split to multiple registers, assume that thre is some
205    // overhead to this.
206    // TODO: Once we have extract/insert subvector cost we need to use them.
207    if (LT.first > 1)
208      return LT.first * 2;
209    return LT.first * 1;
210  }
211
212  if (!TLI->isOperationExpand(ISD, LT.second)) {
213    // If the operation is custom lowered then assume
214    // thare the code is twice as expensive.
215    return LT.first * 2;
216  }
217
218  // Else, assume that we need to scalarize this op.
219  if (Ty->isVectorTy()) {
220    unsigned Num = Ty->getVectorNumElements();
221    unsigned Cost = TopTTI->getArithmeticInstrCost(Opcode, Ty->getScalarType());
222    // return the cost of multiple scalar invocation plus the cost of inserting
223    // and extracting the values.
224    return getScalarizationOverhead(Ty, true, true) + Num * Cost;
225  }
226
227  // We don't know anything about this scalar instruction.
228  return 1;
229}
230
231unsigned BasicTTI::getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,
232                                  Type *SubTp) const {
233  return 1;
234}
235
236unsigned BasicTTI::getCastInstrCost(unsigned Opcode, Type *Dst,
237                                    Type *Src) const {
238  int ISD = TLI->InstructionOpcodeToISD(Opcode);
239  assert(ISD && "Invalid opcode");
240
241  std::pair<unsigned, MVT> SrcLT = TLI->getTypeLegalizationCost(Src);
242  std::pair<unsigned, MVT> DstLT = TLI->getTypeLegalizationCost(Dst);
243
244  // Check for NOOP conversions.
245  if (SrcLT.first == DstLT.first &&
246      SrcLT.second.getSizeInBits() == DstLT.second.getSizeInBits()) {
247
248      // Bitcast between types that are legalized to the same type are free.
249      if (Opcode == Instruction::BitCast || Opcode == Instruction::Trunc)
250        return 0;
251  }
252
253  if (Opcode == Instruction::Trunc &&
254      TLI->isTruncateFree(SrcLT.second, DstLT.second))
255    return 0;
256
257  if (Opcode == Instruction::ZExt &&
258      TLI->isZExtFree(SrcLT.second, DstLT.second))
259    return 0;
260
261  // If the cast is marked as legal (or promote) then assume low cost.
262  if (TLI->isOperationLegalOrPromote(ISD, DstLT.second))
263    return 1;
264
265  // Handle scalar conversions.
266  if (!Src->isVectorTy() && !Dst->isVectorTy()) {
267
268    // Scalar bitcasts are usually free.
269    if (Opcode == Instruction::BitCast)
270      return 0;
271
272    // Just check the op cost. If the operation is legal then assume it costs 1.
273    if (!TLI->isOperationExpand(ISD, DstLT.second))
274      return  1;
275
276    // Assume that illegal scalar instruction are expensive.
277    return 4;
278  }
279
280  // Check vector-to-vector casts.
281  if (Dst->isVectorTy() && Src->isVectorTy()) {
282
283    // If the cast is between same-sized registers, then the check is simple.
284    if (SrcLT.first == DstLT.first &&
285        SrcLT.second.getSizeInBits() == DstLT.second.getSizeInBits()) {
286
287      // Assume that Zext is done using AND.
288      if (Opcode == Instruction::ZExt)
289        return 1;
290
291      // Assume that sext is done using SHL and SRA.
292      if (Opcode == Instruction::SExt)
293        return 2;
294
295      // Just check the op cost. If the operation is legal then assume it costs
296      // 1 and multiply by the type-legalization overhead.
297      if (!TLI->isOperationExpand(ISD, DstLT.second))
298        return SrcLT.first * 1;
299    }
300
301    // If we are converting vectors and the operation is illegal, or
302    // if the vectors are legalized to different types, estimate the
303    // scalarization costs.
304    unsigned Num = Dst->getVectorNumElements();
305    unsigned Cost = TopTTI->getCastInstrCost(Opcode, Dst->getScalarType(),
306                                             Src->getScalarType());
307
308    // Return the cost of multiple scalar invocation plus the cost of
309    // inserting and extracting the values.
310    return getScalarizationOverhead(Dst, true, true) + Num * Cost;
311  }
312
313  // We already handled vector-to-vector and scalar-to-scalar conversions. This
314  // is where we handle bitcast between vectors and scalars. We need to assume
315  //  that the conversion is scalarized in one way or another.
316  if (Opcode == Instruction::BitCast)
317    // Illegal bitcasts are done by storing and loading from a stack slot.
318    return (Src->isVectorTy()? getScalarizationOverhead(Src, false, true):0) +
319           (Dst->isVectorTy()? getScalarizationOverhead(Dst, true, false):0);
320
321  llvm_unreachable("Unhandled cast");
322 }
323
324unsigned BasicTTI::getCFInstrCost(unsigned Opcode) const {
325  // Branches are assumed to be predicted.
326  return 0;
327}
328
329unsigned BasicTTI::getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
330                                      Type *CondTy) const {
331  int ISD = TLI->InstructionOpcodeToISD(Opcode);
332  assert(ISD && "Invalid opcode");
333
334  // Selects on vectors are actually vector selects.
335  if (ISD == ISD::SELECT) {
336    assert(CondTy && "CondTy must exist");
337    if (CondTy->isVectorTy())
338      ISD = ISD::VSELECT;
339  }
340
341  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(ValTy);
342
343  if (!TLI->isOperationExpand(ISD, LT.second)) {
344    // The operation is legal. Assume it costs 1. Multiply
345    // by the type-legalization overhead.
346    return LT.first * 1;
347  }
348
349  // Otherwise, assume that the cast is scalarized.
350  if (ValTy->isVectorTy()) {
351    unsigned Num = ValTy->getVectorNumElements();
352    if (CondTy)
353      CondTy = CondTy->getScalarType();
354    unsigned Cost = TopTTI->getCmpSelInstrCost(Opcode, ValTy->getScalarType(),
355                                               CondTy);
356
357    // Return the cost of multiple scalar invocation plus the cost of inserting
358    // and extracting the values.
359    return getScalarizationOverhead(ValTy, true, false) + Num * Cost;
360  }
361
362  // Unknown scalar opcode.
363  return 1;
364}
365
366unsigned BasicTTI::getVectorInstrCost(unsigned Opcode, Type *Val,
367                                      unsigned Index) const {
368  return 1;
369}
370
371unsigned BasicTTI::getMemoryOpCost(unsigned Opcode, Type *Src,
372                                   unsigned Alignment,
373                                   unsigned AddressSpace) const {
374  assert(!Src->isVoidTy() && "Invalid type");
375  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Src);
376
377  // Assume that all loads of legal types cost 1.
378  return LT.first;
379}
380
381unsigned BasicTTI::getIntrinsicInstrCost(Intrinsic::ID, Type *RetTy,
382                                         ArrayRef<Type *> Tys) const {
383  // assume that we need to scalarize this intrinsic.
384  unsigned ScalarizationCost = 0;
385  unsigned ScalarCalls = 1;
386  if (RetTy->isVectorTy()) {
387    ScalarizationCost = getScalarizationOverhead(RetTy, true, false);
388    ScalarCalls = std::max(ScalarCalls, RetTy->getVectorNumElements());
389  }
390  for (unsigned i = 0, ie = Tys.size(); i != ie; ++i) {
391    if (Tys[i]->isVectorTy()) {
392      ScalarizationCost += getScalarizationOverhead(Tys[i], false, true);
393      ScalarCalls = std::max(ScalarCalls, RetTy->getVectorNumElements());
394    }
395  }
396  return ScalarCalls + ScalarizationCost;
397}
398
399unsigned BasicTTI::getNumberOfParts(Type *Tp) const {
400  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Tp);
401  return LT.first;
402}
403