BasicTargetTransformInfo.cpp revision 9eb366acba65b5779d2129db3a6fb6a0414572d4 
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,
89                                          OperandValueKind,
90                                          OperandValueKind) const;
91  virtual unsigned getShuffleCost(ShuffleKind Kind, Type *Tp,
92                                  int Index, Type *SubTp) const;
93  virtual unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
94                                    Type *Src) const;
95  virtual unsigned getCFInstrCost(unsigned Opcode) const;
96  virtual unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
97                                      Type *CondTy) const;
98  virtual unsigned getVectorInstrCost(unsigned Opcode, Type *Val,
99                                      unsigned Index) const;
100  virtual unsigned getMemoryOpCost(unsigned Opcode, Type *Src,
101                                   unsigned Alignment,
102                                   unsigned AddressSpace) const;
103  virtual unsigned getIntrinsicInstrCost(Intrinsic::ID, Type *RetTy,
104                                         ArrayRef<Type*> Tys) const;
105  virtual unsigned getNumberOfParts(Type *Tp) const;
106  virtual unsigned getAddressComputationCost(Type *Ty) const;
107
108  /// @}
109};
110
111}
112
113INITIALIZE_AG_PASS(BasicTTI, TargetTransformInfo, "basictti",
114                   "Target independent code generator's TTI", true, true, false)
115char BasicTTI::ID = 0;
116
117ImmutablePass *
118llvm::createBasicTargetTransformInfoPass(const TargetLoweringBase *TLI) {
119  return new BasicTTI(TLI);
120}
121
122
123bool BasicTTI::isLegalAddImmediate(int64_t imm) const {
124  return TLI->isLegalAddImmediate(imm);
125}
126
127bool BasicTTI::isLegalICmpImmediate(int64_t imm) const {
128  return TLI->isLegalICmpImmediate(imm);
129}
130
131bool BasicTTI::isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV,
132                                     int64_t BaseOffset, bool HasBaseReg,
133                                     int64_t Scale) const {
134  TargetLoweringBase::AddrMode AM;
135  AM.BaseGV = BaseGV;
136  AM.BaseOffs = BaseOffset;
137  AM.HasBaseReg = HasBaseReg;
138  AM.Scale = Scale;
139  return TLI->isLegalAddressingMode(AM, Ty);
140}
141
142bool BasicTTI::isTruncateFree(Type *Ty1, Type *Ty2) const {
143  return TLI->isTruncateFree(Ty1, Ty2);
144}
145
146bool BasicTTI::isTypeLegal(Type *Ty) const {
147  EVT T = TLI->getValueType(Ty);
148  return TLI->isTypeLegal(T);
149}
150
151unsigned BasicTTI::getJumpBufAlignment() const {
152  return TLI->getJumpBufAlignment();
153}
154
155unsigned BasicTTI::getJumpBufSize() const {
156  return TLI->getJumpBufSize();
157}
158
159bool BasicTTI::shouldBuildLookupTables() const {
160  return TLI->supportJumpTables() &&
161      (TLI->isOperationLegalOrCustom(ISD::BR_JT, MVT::Other) ||
162       TLI->isOperationLegalOrCustom(ISD::BRIND, MVT::Other));
163}
164
165//===----------------------------------------------------------------------===//
166//
167// Calls used by the vectorizers.
168//
169//===----------------------------------------------------------------------===//
170
171unsigned BasicTTI::getScalarizationOverhead(Type *Ty, bool Insert,
172                                            bool Extract) const {
173  assert (Ty->isVectorTy() && "Can only scalarize vectors");
174  unsigned Cost = 0;
175
176  for (int i = 0, e = Ty->getVectorNumElements(); i < e; ++i) {
177    if (Insert)
178      Cost += TopTTI->getVectorInstrCost(Instruction::InsertElement, Ty, i);
179    if (Extract)
180      Cost += TopTTI->getVectorInstrCost(Instruction::ExtractElement, Ty, i);
181  }
182
183  return Cost;
184}
185
186unsigned BasicTTI::getNumberOfRegisters(bool Vector) const {
187  return 1;
188}
189
190unsigned BasicTTI::getRegisterBitWidth(bool Vector) const {
191  return 32;
192}
193
194unsigned BasicTTI::getMaximumUnrollFactor() const {
195  return 1;
196}
197
198unsigned BasicTTI::getArithmeticInstrCost(unsigned Opcode, Type *Ty,
199                                          OperandValueKind,
200                                          OperandValueKind) const {
201  // Check if any of the operands are vector operands.
202  int ISD = TLI->InstructionOpcodeToISD(Opcode);
203  assert(ISD && "Invalid opcode");
204
205  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Ty);
206
207  bool IsFloat = Ty->getScalarType()->isFloatingPointTy();
208  unsigned OpCost = (IsFloat ? 2 : 1);
209
210  if (TLI->isOperationLegalOrPromote(ISD, LT.second)) {
211    // The operation is legal. Assume it costs 1.
212    // If the type is split to multiple registers, assume that thre is some
213    // overhead to this.
214    // TODO: Once we have extract/insert subvector cost we need to use them.
215    if (LT.first > 1)
216      return LT.first * 2 * OpCost;
217    return LT.first * 1 * OpCost;
218  }
219
220  if (!TLI->isOperationExpand(ISD, LT.second)) {
221    // If the operation is custom lowered then assume
222    // thare the code is twice as expensive.
223    return LT.first * 2 * OpCost;
224  }
225
226  // Else, assume that we need to scalarize this op.
227  if (Ty->isVectorTy()) {
228    unsigned Num = Ty->getVectorNumElements();
229    unsigned Cost = TopTTI->getArithmeticInstrCost(Opcode, Ty->getScalarType());
230    // return the cost of multiple scalar invocation plus the cost of inserting
231    // and extracting the values.
232    return getScalarizationOverhead(Ty, true, true) + Num * Cost;
233  }
234
235  // We don't know anything about this scalar instruction.
236  return OpCost;
237}
238
239unsigned BasicTTI::getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,
240                                  Type *SubTp) const {
241  return 1;
242}
243
244unsigned BasicTTI::getCastInstrCost(unsigned Opcode, Type *Dst,
245                                    Type *Src) const {
246  int ISD = TLI->InstructionOpcodeToISD(Opcode);
247  assert(ISD && "Invalid opcode");
248
249  std::pair<unsigned, MVT> SrcLT = TLI->getTypeLegalizationCost(Src);
250  std::pair<unsigned, MVT> DstLT = TLI->getTypeLegalizationCost(Dst);
251
252  // Check for NOOP conversions.
253  if (SrcLT.first == DstLT.first &&
254      SrcLT.second.getSizeInBits() == DstLT.second.getSizeInBits()) {
255
256      // Bitcast between types that are legalized to the same type are free.
257      if (Opcode == Instruction::BitCast || Opcode == Instruction::Trunc)
258        return 0;
259  }
260
261  if (Opcode == Instruction::Trunc &&
262      TLI->isTruncateFree(SrcLT.second, DstLT.second))
263    return 0;
264
265  if (Opcode == Instruction::ZExt &&
266      TLI->isZExtFree(SrcLT.second, DstLT.second))
267    return 0;
268
269  // If the cast is marked as legal (or promote) then assume low cost.
270  if (TLI->isOperationLegalOrPromote(ISD, DstLT.second))
271    return 1;
272
273  // Handle scalar conversions.
274  if (!Src->isVectorTy() && !Dst->isVectorTy()) {
275
276    // Scalar bitcasts are usually free.
277    if (Opcode == Instruction::BitCast)
278      return 0;
279
280    // Just check the op cost. If the operation is legal then assume it costs 1.
281    if (!TLI->isOperationExpand(ISD, DstLT.second))
282      return  1;
283
284    // Assume that illegal scalar instruction are expensive.
285    return 4;
286  }
287
288  // Check vector-to-vector casts.
289  if (Dst->isVectorTy() && Src->isVectorTy()) {
290
291    // If the cast is between same-sized registers, then the check is simple.
292    if (SrcLT.first == DstLT.first &&
293        SrcLT.second.getSizeInBits() == DstLT.second.getSizeInBits()) {
294
295      // Assume that Zext is done using AND.
296      if (Opcode == Instruction::ZExt)
297        return 1;
298
299      // Assume that sext is done using SHL and SRA.
300      if (Opcode == Instruction::SExt)
301        return 2;
302
303      // Just check the op cost. If the operation is legal then assume it costs
304      // 1 and multiply by the type-legalization overhead.
305      if (!TLI->isOperationExpand(ISD, DstLT.second))
306        return SrcLT.first * 1;
307    }
308
309    // If we are converting vectors and the operation is illegal, or
310    // if the vectors are legalized to different types, estimate the
311    // scalarization costs.
312    unsigned Num = Dst->getVectorNumElements();
313    unsigned Cost = TopTTI->getCastInstrCost(Opcode, Dst->getScalarType(),
314                                             Src->getScalarType());
315
316    // Return the cost of multiple scalar invocation plus the cost of
317    // inserting and extracting the values.
318    return getScalarizationOverhead(Dst, true, true) + Num * Cost;
319  }
320
321  // We already handled vector-to-vector and scalar-to-scalar conversions. This
322  // is where we handle bitcast between vectors and scalars. We need to assume
323  //  that the conversion is scalarized in one way or another.
324  if (Opcode == Instruction::BitCast)
325    // Illegal bitcasts are done by storing and loading from a stack slot.
326    return (Src->isVectorTy()? getScalarizationOverhead(Src, false, true):0) +
327           (Dst->isVectorTy()? getScalarizationOverhead(Dst, true, false):0);
328
329  llvm_unreachable("Unhandled cast");
330 }
331
332unsigned BasicTTI::getCFInstrCost(unsigned Opcode) const {
333  // Branches are assumed to be predicted.
334  return 0;
335}
336
337unsigned BasicTTI::getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
338                                      Type *CondTy) const {
339  int ISD = TLI->InstructionOpcodeToISD(Opcode);
340  assert(ISD && "Invalid opcode");
341
342  // Selects on vectors are actually vector selects.
343  if (ISD == ISD::SELECT) {
344    assert(CondTy && "CondTy must exist");
345    if (CondTy->isVectorTy())
346      ISD = ISD::VSELECT;
347  }
348
349  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(ValTy);
350
351  if (!TLI->isOperationExpand(ISD, LT.second)) {
352    // The operation is legal. Assume it costs 1. Multiply
353    // by the type-legalization overhead.
354    return LT.first * 1;
355  }
356
357  // Otherwise, assume that the cast is scalarized.
358  if (ValTy->isVectorTy()) {
359    unsigned Num = ValTy->getVectorNumElements();
360    if (CondTy)
361      CondTy = CondTy->getScalarType();
362    unsigned Cost = TopTTI->getCmpSelInstrCost(Opcode, ValTy->getScalarType(),
363                                               CondTy);
364
365    // Return the cost of multiple scalar invocation plus the cost of inserting
366    // and extracting the values.
367    return getScalarizationOverhead(ValTy, true, false) + Num * Cost;
368  }
369
370  // Unknown scalar opcode.
371  return 1;
372}
373
374unsigned BasicTTI::getVectorInstrCost(unsigned Opcode, Type *Val,
375                                      unsigned Index) const {
376  return 1;
377}
378
379unsigned BasicTTI::getMemoryOpCost(unsigned Opcode, Type *Src,
380                                   unsigned Alignment,
381                                   unsigned AddressSpace) const {
382  assert(!Src->isVoidTy() && "Invalid type");
383  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Src);
384
385  // Assume that all loads of legal types cost 1.
386  return LT.first;
387}
388
389unsigned BasicTTI::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy,
390                                         ArrayRef<Type *> Tys) const {
391  unsigned ISD = 0;
392  switch (IID) {
393  default: {
394    // Assume that we need to scalarize this intrinsic.
395    unsigned ScalarizationCost = 0;
396    unsigned ScalarCalls = 1;
397    if (RetTy->isVectorTy()) {
398      ScalarizationCost = getScalarizationOverhead(RetTy, true, false);
399      ScalarCalls = std::max(ScalarCalls, RetTy->getVectorNumElements());
400    }
401    for (unsigned i = 0, ie = Tys.size(); i != ie; ++i) {
402      if (Tys[i]->isVectorTy()) {
403        ScalarizationCost += getScalarizationOverhead(Tys[i], false, true);
404        ScalarCalls = std::max(ScalarCalls, RetTy->getVectorNumElements());
405      }
406    }
407
408    return ScalarCalls + ScalarizationCost;
409  }
410  // Look for intrinsics that can be lowered directly or turned into a scalar
411  // intrinsic call.
412  case Intrinsic::sqrt:    ISD = ISD::FSQRT;  break;
413  case Intrinsic::sin:     ISD = ISD::FSIN;   break;
414  case Intrinsic::cos:     ISD = ISD::FCOS;   break;
415  case Intrinsic::exp:     ISD = ISD::FEXP;   break;
416  case Intrinsic::exp2:    ISD = ISD::FEXP2;  break;
417  case Intrinsic::log:     ISD = ISD::FLOG;   break;
418  case Intrinsic::log10:   ISD = ISD::FLOG10; break;
419  case Intrinsic::log2:    ISD = ISD::FLOG2;  break;
420  case Intrinsic::fabs:    ISD = ISD::FABS;   break;
421  case Intrinsic::floor:   ISD = ISD::FFLOOR; break;
422  case Intrinsic::ceil:    ISD = ISD::FCEIL;  break;
423  case Intrinsic::trunc:   ISD = ISD::FTRUNC; break;
424  case Intrinsic::rint:    ISD = ISD::FRINT;  break;
425  case Intrinsic::pow:     ISD = ISD::FPOW;   break;
426  case Intrinsic::fma:     ISD = ISD::FMA;    break;
427  case Intrinsic::fmuladd: ISD = ISD::FMA;    break; // FIXME: mul + add?
428  }
429
430  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(RetTy);
431
432  if (TLI->isOperationLegalOrPromote(ISD, LT.second)) {
433    // The operation is legal. Assume it costs 1.
434    // If the type is split to multiple registers, assume that thre is some
435    // overhead to this.
436    // TODO: Once we have extract/insert subvector cost we need to use them.
437    if (LT.first > 1)
438      return LT.first * 2;
439    return LT.first * 1;
440  }
441
442  if (!TLI->isOperationExpand(ISD, LT.second)) {
443    // If the operation is custom lowered then assume
444    // thare the code is twice as expensive.
445    return LT.first * 2;
446  }
447
448  // Else, assume that we need to scalarize this intrinsic. For math builtins
449  // this will emit a costly libcall, adding call overhead and spills. Make it
450  // very expensive.
451  if (RetTy->isVectorTy()) {
452    unsigned Num = RetTy->getVectorNumElements();
453    unsigned Cost = TopTTI->getIntrinsicInstrCost(IID, RetTy->getScalarType(),
454                                                  Tys);
455    return 10 * Cost * Num;
456  }
457
458  // This is going to be turned into a library call, make it expensive.
459  return 10;
460}
461
462unsigned BasicTTI::getNumberOfParts(Type *Tp) const {
463  std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Tp);
464  return LT.first;
465}
466
467unsigned BasicTTI::getAddressComputationCost(Type *Ty) const {
468  return 0;
469}
470