llvm.org GIT mirror llvm / 0392724 lib / Target / AMDGPU / AMDGPUPromoteAlloca.cpp
0392724

Tree @0392724 (Download .tar.gz)

AMDGPUPromoteAlloca.cpp @0392724raw · history · blame

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
//===-- AMDGPUPromoteAlloca.cpp - Promote Allocas -------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This pass eliminates allocas by either converting them into vectors or
// by migrating them to local address space.
//
//===----------------------------------------------------------------------===//

#include "AMDGPU.h"
#include "AMDGPUSubtarget.h"
#include "Utils/AMDGPUBaseInfo.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <map>
#include <tuple>
#include <utility>
#include <vector>

#define DEBUG_TYPE "amdgpu-promote-alloca"

using namespace llvm;

namespace {

static cl::opt<bool> DisablePromoteAllocaToVector(
  "disable-promote-alloca-to-vector",
  cl::desc("Disable promote alloca to vector"),
  cl::init(false));

static cl::opt<bool> DisablePromoteAllocaToLDS(
  "disable-promote-alloca-to-lds",
  cl::desc("Disable promote alloca to LDS"),
  cl::init(false));

// FIXME: This can create globals so should be a module pass.
class AMDGPUPromoteAlloca : public FunctionPass {
private:
  const TargetMachine *TM;
  Module *Mod = nullptr;
  const DataLayout *DL = nullptr;

  // FIXME: This should be per-kernel.
  uint32_t LocalMemLimit = 0;
  uint32_t CurrentLocalMemUsage = 0;

  bool IsAMDGCN = false;
  bool IsAMDHSA = false;

  std::pair<Value *, Value *> getLocalSizeYZ(IRBuilder<> &Builder);
  Value *getWorkitemID(IRBuilder<> &Builder, unsigned N);

  /// BaseAlloca is the alloca root the search started from.
  /// Val may be that alloca or a recursive user of it.
  bool collectUsesWithPtrTypes(Value *BaseAlloca,
                               Value *Val,
                               std::vector<Value*> &WorkList) const;

  /// Val is a derived pointer from Alloca. OpIdx0/OpIdx1 are the operand
  /// indices to an instruction with 2 pointer inputs (e.g. select, icmp).
  /// Returns true if both operands are derived from the same alloca. Val should
  /// be the same value as one of the input operands of UseInst.
  bool binaryOpIsDerivedFromSameAlloca(Value *Alloca, Value *Val,
                                       Instruction *UseInst,
                                       int OpIdx0, int OpIdx1) const;

  /// Check whether we have enough local memory for promotion.
  bool hasSufficientLocalMem(const Function &F);

public:
  static char ID;

  AMDGPUPromoteAlloca() : FunctionPass(ID) {}

  bool doInitialization(Module &M) override;
  bool runOnFunction(Function &F) override;

  StringRef getPassName() const override { return "AMDGPU Promote Alloca"; }

  bool handleAlloca(AllocaInst &I, bool SufficientLDS);

  void getAnalysisUsage(AnalysisUsage &AU) const override {
    AU.setPreservesCFG();
    FunctionPass::getAnalysisUsage(AU);
  }
};

} // end anonymous namespace

char AMDGPUPromoteAlloca::ID = 0;

INITIALIZE_PASS(AMDGPUPromoteAlloca, DEBUG_TYPE,
                "AMDGPU promote alloca to vector or LDS", false, false)

char &llvm::AMDGPUPromoteAllocaID = AMDGPUPromoteAlloca::ID;

bool AMDGPUPromoteAlloca::doInitialization(Module &M) {
  Mod = &M;
  DL = &Mod->getDataLayout();

  return false;
}

bool AMDGPUPromoteAlloca::runOnFunction(Function &F) {
  if (skipFunction(F))
    return false;

  if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>())
    TM = &TPC->getTM<TargetMachine>();
  else
    return false;

  const Triple &TT = TM->getTargetTriple();
  IsAMDGCN = TT.getArch() == Triple::amdgcn;
  IsAMDHSA = TT.getOS() == Triple::AMDHSA;

  const AMDGPUSubtarget &ST = AMDGPUSubtarget::get(*TM, F);
  if (!ST.isPromoteAllocaEnabled())
    return false;

  bool SufficientLDS = hasSufficientLocalMem(F);
  bool Changed = false;
  BasicBlock &EntryBB = *F.begin();

  SmallVector<AllocaInst *, 16> Allocas;
  for (Instruction &I : EntryBB) {
    if (AllocaInst *AI = dyn_cast<AllocaInst>(&I))
      Allocas.push_back(AI);
  }

  for (AllocaInst *AI : Allocas) {
    if (handleAlloca(*AI, SufficientLDS))
      Changed = true;
  }

  return Changed;
}

std::pair<Value *, Value *>
AMDGPUPromoteAlloca::getLocalSizeYZ(IRBuilder<> &Builder) {
  const Function &F = *Builder.GetInsertBlock()->getParent();
  const AMDGPUSubtarget &ST = AMDGPUSubtarget::get(*TM, F);

  if (!IsAMDHSA) {
    Function *LocalSizeYFn
      = Intrinsic::getDeclaration(Mod, Intrinsic::r600_read_local_size_y);
    Function *LocalSizeZFn
      = Intrinsic::getDeclaration(Mod, Intrinsic::r600_read_local_size_z);

    CallInst *LocalSizeY = Builder.CreateCall(LocalSizeYFn, {});
    CallInst *LocalSizeZ = Builder.CreateCall(LocalSizeZFn, {});

    ST.makeLIDRangeMetadata(LocalSizeY);
    ST.makeLIDRangeMetadata(LocalSizeZ);

    return std::make_pair(LocalSizeY, LocalSizeZ);
  }

  // We must read the size out of the dispatch pointer.
  assert(IsAMDGCN);

  // We are indexing into this struct, and want to extract the workgroup_size_*
  // fields.
  //
  //   typedef struct hsa_kernel_dispatch_packet_s {
  //     uint16_t header;
  //     uint16_t setup;
  //     uint16_t workgroup_size_x ;
  //     uint16_t workgroup_size_y;
  //     uint16_t workgroup_size_z;
  //     uint16_t reserved0;
  //     uint32_t grid_size_x ;
  //     uint32_t grid_size_y ;
  //     uint32_t grid_size_z;
  //
  //     uint32_t private_segment_size;
  //     uint32_t group_segment_size;
  //     uint64_t kernel_object;
  //
  // #ifdef HSA_LARGE_MODEL
  //     void *kernarg_address;
  // #elif defined HSA_LITTLE_ENDIAN
  //     void *kernarg_address;
  //     uint32_t reserved1;
  // #else
  //     uint32_t reserved1;
  //     void *kernarg_address;
  // #endif
  //     uint64_t reserved2;
  //     hsa_signal_t completion_signal; // uint64_t wrapper
  //   } hsa_kernel_dispatch_packet_t
  //
  Function *DispatchPtrFn
    = Intrinsic::getDeclaration(Mod, Intrinsic::amdgcn_dispatch_ptr);

  CallInst *DispatchPtr = Builder.CreateCall(DispatchPtrFn, {});
  DispatchPtr->addAttribute(AttributeList::ReturnIndex, Attribute::NoAlias);
  DispatchPtr->addAttribute(AttributeList::ReturnIndex, Attribute::NonNull);

  // Size of the dispatch packet struct.
  DispatchPtr->addDereferenceableAttr(AttributeList::ReturnIndex, 64);

  Type *I32Ty = Type::getInt32Ty(Mod->getContext());
  Value *CastDispatchPtr = Builder.CreateBitCast(
    DispatchPtr, PointerType::get(I32Ty, AMDGPUAS::CONSTANT_ADDRESS));

  // We could do a single 64-bit load here, but it's likely that the basic
  // 32-bit and extract sequence is already present, and it is probably easier
  // to CSE this. The loads should be mergable later anyway.
  Value *GEPXY = Builder.CreateConstInBoundsGEP1_64(I32Ty, CastDispatchPtr, 1);
  LoadInst *LoadXY = Builder.CreateAlignedLoad(I32Ty, GEPXY, 4);

  Value *GEPZU = Builder.CreateConstInBoundsGEP1_64(I32Ty, CastDispatchPtr, 2);
  LoadInst *LoadZU = Builder.CreateAlignedLoad(I32Ty, GEPZU, 4);

  MDNode *MD = MDNode::get(Mod->getContext(), None);
  LoadXY->setMetadata(LLVMContext::MD_invariant_load, MD);
  LoadZU->setMetadata(LLVMContext::MD_invariant_load, MD);
  ST.makeLIDRangeMetadata(LoadZU);

  // Extract y component. Upper half of LoadZU should be zero already.
  Value *Y = Builder.CreateLShr(LoadXY, 16);

  return std::make_pair(Y, LoadZU);
}

Value *AMDGPUPromoteAlloca::getWorkitemID(IRBuilder<> &Builder, unsigned N) {
  const AMDGPUSubtarget &ST =
      AMDGPUSubtarget::get(*TM, *Builder.GetInsertBlock()->getParent());
  Intrinsic::ID IntrID = Intrinsic::ID::not_intrinsic;

  switch (N) {
  case 0:
    IntrID = IsAMDGCN ? Intrinsic::amdgcn_workitem_id_x
      : Intrinsic::r600_read_tidig_x;
    break;
  case 1:
    IntrID = IsAMDGCN ? Intrinsic::amdgcn_workitem_id_y
      : Intrinsic::r600_read_tidig_y;
    break;

  case 2:
    IntrID = IsAMDGCN ? Intrinsic::amdgcn_workitem_id_z
      : Intrinsic::r600_read_tidig_z;
    break;
  default:
    llvm_unreachable("invalid dimension");
  }

  Function *WorkitemIdFn = Intrinsic::getDeclaration(Mod, IntrID);
  CallInst *CI = Builder.CreateCall(WorkitemIdFn);
  ST.makeLIDRangeMetadata(CI);

  return CI;
}

static VectorType *arrayTypeToVecType(ArrayType *ArrayTy) {
  return VectorType::get(ArrayTy->getElementType(),
                         ArrayTy->getNumElements());
}

static Value *
calculateVectorIndex(Value *Ptr,
                     const std::map<GetElementPtrInst *, Value *> &GEPIdx) {
  GetElementPtrInst *GEP = cast<GetElementPtrInst>(Ptr);

  auto I = GEPIdx.find(GEP);
  return I == GEPIdx.end() ? nullptr : I->second;
}

static Value* GEPToVectorIndex(GetElementPtrInst *GEP) {
  // FIXME we only support simple cases
  if (GEP->getNumOperands() != 3)
    return nullptr;

  ConstantInt *I0 = dyn_cast<ConstantInt>(GEP->getOperand(1));
  if (!I0 || !I0->isZero())
    return nullptr;

  return GEP->getOperand(2);
}

// Not an instruction handled below to turn into a vector.
//
// TODO: Check isTriviallyVectorizable for calls and handle other
// instructions.
static bool canVectorizeInst(Instruction *Inst, User *User) {
  switch (Inst->getOpcode()) {
  case Instruction::Load: {
    // Currently only handle the case where the Pointer Operand is a GEP.
    // Also we could not vectorize volatile or atomic loads.
    LoadInst *LI = cast<LoadInst>(Inst);
    if (isa<AllocaInst>(User) &&
        LI->getPointerOperandType() == User->getType() &&
        isa<VectorType>(LI->getType()))
      return true;
    return isa<GetElementPtrInst>(LI->getPointerOperand()) && LI->isSimple();
  }
  case Instruction::BitCast:
    return true;
  case Instruction::Store: {
    // Must be the stored pointer operand, not a stored value, plus
    // since it should be canonical form, the User should be a GEP.
    // Also we could not vectorize volatile or atomic stores.
    StoreInst *SI = cast<StoreInst>(Inst);
    if (isa<AllocaInst>(User) &&
        SI->getPointerOperandType() == User->getType() &&
        isa<VectorType>(SI->getValueOperand()->getType()))
      return true;
    return (SI->getPointerOperand() == User) && isa<GetElementPtrInst>(User) && SI->isSimple();
  }
  default:
    return false;
  }
}

static bool tryPromoteAllocaToVector(AllocaInst *Alloca) {

  if (DisablePromoteAllocaToVector) {
    LLVM_DEBUG(dbgs() << "  Promotion alloca to vector is disabled\n");
    return false;
  }

  Type *AT = Alloca->getAllocatedType();
  SequentialType *AllocaTy = dyn_cast<SequentialType>(AT);

  LLVM_DEBUG(dbgs() << "Alloca candidate for vectorization\n");

  // FIXME: There is no reason why we can't support larger arrays, we
  // are just being conservative for now.
  // FIXME: We also reject alloca's of the form [ 2 x [ 2 x i32 ]] or equivalent. Potentially these
  // could also be promoted but we don't currently handle this case
  if (!AllocaTy ||
      AllocaTy->getNumElements() > 16 ||
      AllocaTy->getNumElements() < 2 ||
      !VectorType::isValidElementType(AllocaTy->getElementType())) {
    LLVM_DEBUG(dbgs() << "  Cannot convert type to vector\n");
    return false;
  }

  std::map<GetElementPtrInst*, Value*> GEPVectorIdx;
  std::vector<Value*> WorkList;
  for (User *AllocaUser : Alloca->users()) {
    GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(AllocaUser);
    if (!GEP) {
      if (!canVectorizeInst(cast<Instruction>(AllocaUser), Alloca))
        return false;

      WorkList.push_back(AllocaUser);
      continue;
    }

    Value *Index = GEPToVectorIndex(GEP);

    // If we can't compute a vector index from this GEP, then we can't
    // promote this alloca to vector.
    if (!Index) {
      LLVM_DEBUG(dbgs() << "  Cannot compute vector index for GEP " << *GEP
                        << '\n');
      return false;
    }

    GEPVectorIdx[GEP] = Index;
    for (User *GEPUser : AllocaUser->users()) {
      if (!canVectorizeInst(cast<Instruction>(GEPUser), AllocaUser))
        return false;

      WorkList.push_back(GEPUser);
    }
  }

  VectorType *VectorTy = dyn_cast<VectorType>(AllocaTy);
  if (!VectorTy)
    VectorTy = arrayTypeToVecType(cast<ArrayType>(AllocaTy));

  LLVM_DEBUG(dbgs() << "  Converting alloca to vector " << *AllocaTy << " -> "
                    << *VectorTy << '\n');

  for (Value *V : WorkList) {
    Instruction *Inst = cast<Instruction>(V);
    IRBuilder<> Builder(Inst);
    switch (Inst->getOpcode()) {
    case Instruction::Load: {
      if (Inst->getType() == AT)
        break;

      Type *VecPtrTy = VectorTy->getPointerTo(AMDGPUAS::PRIVATE_ADDRESS);
      Value *Ptr = cast<LoadInst>(Inst)->getPointerOperand();
      Value *Index = calculateVectorIndex(Ptr, GEPVectorIdx);

      Value *BitCast = Builder.CreateBitCast(Alloca, VecPtrTy);
      Value *VecValue = Builder.CreateLoad(VectorTy, BitCast);
      Value *ExtractElement = Builder.CreateExtractElement(VecValue, Index);
      Inst->replaceAllUsesWith(ExtractElement);
      Inst->eraseFromParent();
      break;
    }
    case Instruction::Store: {
      StoreInst *SI = cast<StoreInst>(Inst);
      if (SI->getValueOperand()->getType() == AT)
        break;

      Type *VecPtrTy = VectorTy->getPointerTo(AMDGPUAS::PRIVATE_ADDRESS);
      Value *Ptr = SI->getPointerOperand();
      Value *Index = calculateVectorIndex(Ptr, GEPVectorIdx);
      Value *BitCast = Builder.CreateBitCast(Alloca, VecPtrTy);
      Value *VecValue = Builder.CreateLoad(VectorTy, BitCast);
      Value *NewVecValue = Builder.CreateInsertElement(VecValue,
                                                       SI->getValueOperand(),
                                                       Index);
      Builder.CreateStore(NewVecValue, BitCast);
      Inst->eraseFromParent();
      break;
    }
    case Instruction::BitCast:
    case Instruction::AddrSpaceCast:
      break;

    default:
      llvm_unreachable("Inconsistency in instructions promotable to vector");
    }
  }
  return true;
}

static bool isCallPromotable(CallInst *CI) {
  IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
  if (!II)
    return false;

  switch (II->getIntrinsicID()) {
  case Intrinsic::memcpy:
  case Intrinsic::memmove:
  case Intrinsic::memset:
  case Intrinsic::lifetime_start:
  case Intrinsic::lifetime_end:
  case Intrinsic::invariant_start:
  case Intrinsic::invariant_end:
  case Intrinsic::launder_invariant_group:
  case Intrinsic::strip_invariant_group:
  case Intrinsic::objectsize:
    return true;
  default:
    return false;
  }
}

bool AMDGPUPromoteAlloca::binaryOpIsDerivedFromSameAlloca(Value *BaseAlloca,
                                                          Value *Val,
                                                          Instruction *Inst,
                                                          int OpIdx0,
                                                          int OpIdx1) const {
  // Figure out which operand is the one we might not be promoting.
  Value *OtherOp = Inst->getOperand(OpIdx0);
  if (Val == OtherOp)
    OtherOp = Inst->getOperand(OpIdx1);

  if (isa<ConstantPointerNull>(OtherOp))
    return true;

  Value *OtherObj = GetUnderlyingObject(OtherOp, *DL);
  if (!isa<AllocaInst>(OtherObj))
    return false;

  // TODO: We should be able to replace undefs with the right pointer type.

  // TODO: If we know the other base object is another promotable
  // alloca, not necessarily this alloca, we can do this. The
  // important part is both must have the same address space at
  // the end.
  if (OtherObj != BaseAlloca) {
    LLVM_DEBUG(
        dbgs() << "Found a binary instruction with another alloca object\n");
    return false;
  }

  return true;
}

bool AMDGPUPromoteAlloca::collectUsesWithPtrTypes(
  Value *BaseAlloca,
  Value *Val,
  std::vector<Value*> &WorkList) const {

  for (User *User : Val->users()) {
    if (is_contained(WorkList, User))
      continue;

    if (CallInst *CI = dyn_cast<CallInst>(User)) {
      if (!isCallPromotable(CI))
        return false;

      WorkList.push_back(User);
      continue;
    }

    Instruction *UseInst = cast<Instruction>(User);
    if (UseInst->getOpcode() == Instruction::PtrToInt)
      return false;

    if (LoadInst *LI = dyn_cast<LoadInst>(UseInst)) {
      if (LI->isVolatile())
        return false;

      continue;
    }

    if (StoreInst *SI = dyn_cast<StoreInst>(UseInst)) {
      if (SI->isVolatile())
        return false;

      // Reject if the stored value is not the pointer operand.
      if (SI->getPointerOperand() != Val)
        return false;
    } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UseInst)) {
      if (RMW->isVolatile())
        return false;
    } else if (AtomicCmpXchgInst *CAS = dyn_cast<AtomicCmpXchgInst>(UseInst)) {
      if (CAS->isVolatile())
        return false;
    }

    // Only promote a select if we know that the other select operand
    // is from another pointer that will also be promoted.
    if (ICmpInst *ICmp = dyn_cast<ICmpInst>(UseInst)) {
      if (!binaryOpIsDerivedFromSameAlloca(BaseAlloca, Val, ICmp, 0, 1))
        return false;

      // May need to rewrite constant operands.
      WorkList.push_back(ICmp);
    }

    if (UseInst->getOpcode() == Instruction::AddrSpaceCast) {
      // Give up if the pointer may be captured.
      if (PointerMayBeCaptured(UseInst, true, true))
        return false;
      // Don't collect the users of this.
      WorkList.push_back(User);
      continue;
    }

    if (!User->getType()->isPointerTy())
      continue;

    if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(UseInst)) {
      // Be conservative if an address could be computed outside the bounds of
      // the alloca.
      if (!GEP->isInBounds())
        return false;
    }

    // Only promote a select if we know that the other select operand is from
    // another pointer that will also be promoted.
    if (SelectInst *SI = dyn_cast<SelectInst>(UseInst)) {
      if (!binaryOpIsDerivedFromSameAlloca(BaseAlloca, Val, SI, 1, 2))
        return false;
    }

    // Repeat for phis.
    if (PHINode *Phi = dyn_cast<PHINode>(UseInst)) {
      // TODO: Handle more complex cases. We should be able to replace loops
      // over arrays.
      switch (Phi->getNumIncomingValues()) {
      case 1:
        break;
      case 2:
        if (!binaryOpIsDerivedFromSameAlloca(BaseAlloca, Val, Phi, 0, 1))
          return false;
        break;
      default:
        return false;
      }
    }

    WorkList.push_back(User);
    if (!collectUsesWithPtrTypes(BaseAlloca, User, WorkList))
      return false;
  }

  return true;
}

bool AMDGPUPromoteAlloca::hasSufficientLocalMem(const Function &F) {

  FunctionType *FTy = F.getFunctionType();
  const AMDGPUSubtarget &ST = AMDGPUSubtarget::get(*TM, F);

  // If the function has any arguments in the local address space, then it's
  // possible these arguments require the entire local memory space, so
  // we cannot use local memory in the pass.
  for (Type *ParamTy : FTy->params()) {
    PointerType *PtrTy = dyn_cast<PointerType>(ParamTy);
    if (PtrTy && PtrTy->getAddressSpace() == AMDGPUAS::LOCAL_ADDRESS) {
      LocalMemLimit = 0;
      LLVM_DEBUG(dbgs() << "Function has local memory argument. Promoting to "
                           "local memory disabled.\n");
      return false;
    }
  }

  LocalMemLimit = ST.getLocalMemorySize();
  if (LocalMemLimit == 0)
    return false;

  const DataLayout &DL = Mod->getDataLayout();

  // Check how much local memory is being used by global objects
  CurrentLocalMemUsage = 0;
  for (GlobalVariable &GV : Mod->globals()) {
    if (GV.getType()->getAddressSpace() != AMDGPUAS::LOCAL_ADDRESS)
      continue;

    for (const User *U : GV.users()) {
      const Instruction *Use = dyn_cast<Instruction>(U);
      if (!Use)
        continue;

      if (Use->getParent()->getParent() == &F) {
        unsigned Align = GV.getAlignment();
        if (Align == 0)
          Align = DL.getABITypeAlignment(GV.getValueType());

        // FIXME: Try to account for padding here. The padding is currently
        // determined from the inverse order of uses in the function. I'm not
        // sure if the use list order is in any way connected to this, so the
        // total reported size is likely incorrect.
        uint64_t AllocSize = DL.getTypeAllocSize(GV.getValueType());
        CurrentLocalMemUsage = alignTo(CurrentLocalMemUsage, Align);
        CurrentLocalMemUsage += AllocSize;
        break;
      }
    }
  }

  unsigned MaxOccupancy = ST.getOccupancyWithLocalMemSize(CurrentLocalMemUsage,
                                                          F);

  // Restrict local memory usage so that we don't drastically reduce occupancy,
  // unless it is already significantly reduced.

  // TODO: Have some sort of hint or other heuristics to guess occupancy based
  // on other factors..
  unsigned OccupancyHint = ST.getWavesPerEU(F).second;
  if (OccupancyHint == 0)
    OccupancyHint = 7;

  // Clamp to max value.
  OccupancyHint = std::min(OccupancyHint, ST.getMaxWavesPerEU());

  // Check the hint but ignore it if it's obviously wrong from the existing LDS
  // usage.
  MaxOccupancy = std::min(OccupancyHint, MaxOccupancy);


  // Round up to the next tier of usage.
  unsigned MaxSizeWithWaveCount
    = ST.getMaxLocalMemSizeWithWaveCount(MaxOccupancy, F);

  // Program is possibly broken by using more local mem than available.
  if (CurrentLocalMemUsage > MaxSizeWithWaveCount)
    return false;

  LocalMemLimit = MaxSizeWithWaveCount;

  LLVM_DEBUG(dbgs() << F.getName() << " uses " << CurrentLocalMemUsage
                    << " bytes of LDS\n"
                    << "  Rounding size to " << MaxSizeWithWaveCount
                    << " with a maximum occupancy of " << MaxOccupancy << '\n'
                    << " and " << (LocalMemLimit - CurrentLocalMemUsage)
                    << " available for promotion\n");

  return true;
}

// FIXME: Should try to pick the most likely to be profitable allocas first.
bool AMDGPUPromoteAlloca::handleAlloca(AllocaInst &I, bool SufficientLDS) {
  // Array allocations are probably not worth handling, since an allocation of
  // the array type is the canonical form.
  if (!I.isStaticAlloca() || I.isArrayAllocation())
    return false;

  IRBuilder<> Builder(&I);

  // First try to replace the alloca with a vector
  Type *AllocaTy = I.getAllocatedType();

  LLVM_DEBUG(dbgs() << "Trying to promote " << I << '\n');

  if (tryPromoteAllocaToVector(&I))
    return true; // Promoted to vector.

  if (DisablePromoteAllocaToLDS)
    return false;

  const Function &ContainingFunction = *I.getParent()->getParent();
  CallingConv::ID CC = ContainingFunction.getCallingConv();

  // Don't promote the alloca to LDS for shader calling conventions as the work
  // item ID intrinsics are not supported for these calling conventions.
  // Furthermore not all LDS is available for some of the stages.
  switch (CC) {
  case CallingConv::AMDGPU_KERNEL:
  case CallingConv::SPIR_KERNEL:
    break;
  default:
    LLVM_DEBUG(
        dbgs()
        << " promote alloca to LDS not supported with calling convention.\n");
    return false;
  }

  // Not likely to have sufficient local memory for promotion.
  if (!SufficientLDS)
    return false;

  const AMDGPUSubtarget &ST = AMDGPUSubtarget::get(*TM, ContainingFunction);
  unsigned WorkGroupSize = ST.getFlatWorkGroupSizes(ContainingFunction).second;

  const DataLayout &DL = Mod->getDataLayout();

  unsigned Align = I.getAlignment();
  if (Align == 0)
    Align = DL.getABITypeAlignment(I.getAllocatedType());

  // FIXME: This computed padding is likely wrong since it depends on inverse
  // usage order.
  //
  // FIXME: It is also possible that if we're allowed to use all of the memory
  // could could end up using more than the maximum due to alignment padding.

  uint32_t NewSize = alignTo(CurrentLocalMemUsage, Align);
  uint32_t AllocSize = WorkGroupSize * DL.getTypeAllocSize(AllocaTy);
  NewSize += AllocSize;

  if (NewSize > LocalMemLimit) {
    LLVM_DEBUG(dbgs() << "  " << AllocSize
                      << " bytes of local memory not available to promote\n");
    return false;
  }

  CurrentLocalMemUsage = NewSize;

  std::vector<Value*> WorkList;

  if (!collectUsesWithPtrTypes(&I, &I, WorkList)) {
    LLVM_DEBUG(dbgs() << " Do not know how to convert all uses\n");
    return false;
  }

  LLVM_DEBUG(dbgs() << "Promoting alloca to local memory\n");

  Function *F = I.getParent()->getParent();

  Type *GVTy = ArrayType::get(I.getAllocatedType(), WorkGroupSize);
  GlobalVariable *GV = new GlobalVariable(
      *Mod, GVTy, false, GlobalValue::InternalLinkage,
      UndefValue::get(GVTy),
      Twine(F->getName()) + Twine('.') + I.getName(),
      nullptr,
      GlobalVariable::NotThreadLocal,
      AMDGPUAS::LOCAL_ADDRESS);
  GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
  GV->setAlignment(I.getAlignment());

  Value *TCntY, *TCntZ;

  std::tie(TCntY, TCntZ) = getLocalSizeYZ(Builder);
  Value *TIdX = getWorkitemID(Builder, 0);
  Value *TIdY = getWorkitemID(Builder, 1);
  Value *TIdZ = getWorkitemID(Builder, 2);

  Value *Tmp0 = Builder.CreateMul(TCntY, TCntZ, "", true, true);
  Tmp0 = Builder.CreateMul(Tmp0, TIdX);
  Value *Tmp1 = Builder.CreateMul(TIdY, TCntZ, "", true, true);
  Value *TID = Builder.CreateAdd(Tmp0, Tmp1);
  TID = Builder.CreateAdd(TID, TIdZ);

  Value *Indices[] = {
    Constant::getNullValue(Type::getInt32Ty(Mod->getContext())),
    TID
  };

  Value *Offset = Builder.CreateInBoundsGEP(GVTy, GV, Indices);
  I.mutateType(Offset->getType());
  I.replaceAllUsesWith(Offset);
  I.eraseFromParent();

  for (Value *V : WorkList) {
    CallInst *Call = dyn_cast<CallInst>(V);
    if (!Call) {
      if (ICmpInst *CI = dyn_cast<ICmpInst>(V)) {
        Value *Src0 = CI->getOperand(0);
        Type *EltTy = Src0->getType()->getPointerElementType();
        PointerType *NewTy = PointerType::get(EltTy, AMDGPUAS::LOCAL_ADDRESS);

        if (isa<ConstantPointerNull>(CI->getOperand(0)))
          CI->setOperand(0, ConstantPointerNull::get(NewTy));

        if (isa<ConstantPointerNull>(CI->getOperand(1)))
          CI->setOperand(1, ConstantPointerNull::get(NewTy));

        continue;
      }

      // The operand's value should be corrected on its own and we don't want to
      // touch the users.
      if (isa<AddrSpaceCastInst>(V))
        continue;

      Type *EltTy = V->getType()->getPointerElementType();
      PointerType *NewTy = PointerType::get(EltTy, AMDGPUAS::LOCAL_ADDRESS);

      // FIXME: It doesn't really make sense to try to do this for all
      // instructions.
      V->mutateType(NewTy);

      // Adjust the types of any constant operands.
      if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
        if (isa<ConstantPointerNull>(SI->getOperand(1)))
          SI->setOperand(1, ConstantPointerNull::get(NewTy));

        if (isa<ConstantPointerNull>(SI->getOperand(2)))
          SI->setOperand(2, ConstantPointerNull::get(NewTy));
      } else if (PHINode *Phi = dyn_cast<PHINode>(V)) {
        for (unsigned I = 0, E = Phi->getNumIncomingValues(); I != E; ++I) {
          if (isa<ConstantPointerNull>(Phi->getIncomingValue(I)))
            Phi->setIncomingValue(I, ConstantPointerNull::get(NewTy));
        }
      }

      continue;
    }

    IntrinsicInst *Intr = cast<IntrinsicInst>(Call);
    Builder.SetInsertPoint(Intr);
    switch (Intr->getIntrinsicID()) {
    case Intrinsic::lifetime_start:
    case Intrinsic::lifetime_end:
      // These intrinsics are for address space 0 only
      Intr->eraseFromParent();
      continue;
    case Intrinsic::memcpy: {
      MemCpyInst *MemCpy = cast<MemCpyInst>(Intr);
      Builder.CreateMemCpy(MemCpy->getRawDest(), MemCpy->getDestAlignment(),
                           MemCpy->getRawSource(), MemCpy->getSourceAlignment(),
                           MemCpy->getLength(), MemCpy->isVolatile());
      Intr->eraseFromParent();
      continue;
    }
    case Intrinsic::memmove: {
      MemMoveInst *MemMove = cast<MemMoveInst>(Intr);
      Builder.CreateMemMove(MemMove->getRawDest(), MemMove->getDestAlignment(),
                            MemMove->getRawSource(), MemMove->getSourceAlignment(),
                            MemMove->getLength(), MemMove->isVolatile());
      Intr->eraseFromParent();
      continue;
    }
    case Intrinsic::memset: {
      MemSetInst *MemSet = cast<MemSetInst>(Intr);
      Builder.CreateMemSet(MemSet->getRawDest(), MemSet->getValue(),
                           MemSet->getLength(), MemSet->getDestAlignment(),
                           MemSet->isVolatile());
      Intr->eraseFromParent();
      continue;
    }
    case Intrinsic::invariant_start:
    case Intrinsic::invariant_end:
    case Intrinsic::launder_invariant_group:
    case Intrinsic::strip_invariant_group:
      Intr->eraseFromParent();
      // FIXME: I think the invariant marker should still theoretically apply,
      // but the intrinsics need to be changed to accept pointers with any
      // address space.
      continue;
    case Intrinsic::objectsize: {
      Value *Src = Intr->getOperand(0);
      Type *SrcTy = Src->getType()->getPointerElementType();
      Function *ObjectSize = Intrinsic::getDeclaration(Mod,
        Intrinsic::objectsize,
        { Intr->getType(), PointerType::get(SrcTy, AMDGPUAS::LOCAL_ADDRESS) }
      );

      CallInst *NewCall = Builder.CreateCall(
          ObjectSize,
          {Src, Intr->getOperand(1), Intr->getOperand(2), Intr->getOperand(3)});
      Intr->replaceAllUsesWith(NewCall);
      Intr->eraseFromParent();
      continue;
    }
    default:
      Intr->print(errs());
      llvm_unreachable("Don't know how to promote alloca intrinsic use.");
    }
  }
  return true;
}

FunctionPass *llvm::createAMDGPUPromoteAlloca() {
  return new AMDGPUPromoteAlloca();
}