reference, declarationdefinition
definition → references, declarations, derived classes, virtual overrides
reference to multiple definitions → definitions
unreferenced
    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
//=== AMDGPUPrintfRuntimeBinding.cpp - OpenCL printf implementation -------===//
//
// 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
//
//===----------------------------------------------------------------------===//
// \file
//
// The pass bind printfs to a kernel arg pointer that will be bound to a buffer
// later by the runtime.
//
// This pass traverses the functions in the module and converts
// each call to printf to a sequence of operations that
// store the following into the printf buffer:
// - format string (passed as a module's metadata unique ID)
// - bitwise copies of printf arguments
// The backend passes will need to store metadata in the kernel
//===----------------------------------------------------------------------===//

#include "AMDGPU.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;

#define DEBUG_TYPE "printfToRuntime"
#define DWORD_ALIGN 4

namespace {
class LLVM_LIBRARY_VISIBILITY AMDGPUPrintfRuntimeBinding final
    : public ModulePass {

public:
  static char ID;

  explicit AMDGPUPrintfRuntimeBinding();

private:
  bool runOnModule(Module &M) override;
  void getConversionSpecifiers(SmallVectorImpl<char> &OpConvSpecifiers,
                               StringRef fmt, size_t num_ops) const;

  bool shouldPrintAsStr(char Specifier, Type *OpType) const;
  bool
  lowerPrintfForGpu(Module &M,
                    function_ref<const TargetLibraryInfo &(Function &)> GetTLI);

  void getAnalysisUsage(AnalysisUsage &AU) const override {
    AU.addRequired<TargetLibraryInfoWrapperPass>();
    AU.addRequired<DominatorTreeWrapperPass>();
  }

  Value *simplify(Instruction *I, const TargetLibraryInfo *TLI) {
    return SimplifyInstruction(I, {*TD, TLI, DT});
  }

  const DataLayout *TD;
  const DominatorTree *DT;
  SmallVector<CallInst *, 32> Printfs;
};
} // namespace

char AMDGPUPrintfRuntimeBinding::ID = 0;

INITIALIZE_PASS_BEGIN(AMDGPUPrintfRuntimeBinding,
                      "amdgpu-printf-runtime-binding", "AMDGPU Printf lowering",
                      false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_END(AMDGPUPrintfRuntimeBinding, "amdgpu-printf-runtime-binding",
                    "AMDGPU Printf lowering", false, false)

char &llvm::AMDGPUPrintfRuntimeBindingID = AMDGPUPrintfRuntimeBinding::ID;

namespace llvm {
ModulePass *createAMDGPUPrintfRuntimeBinding() {
  return new AMDGPUPrintfRuntimeBinding();
}
} // namespace llvm

AMDGPUPrintfRuntimeBinding::AMDGPUPrintfRuntimeBinding()
    : ModulePass(ID), TD(nullptr), DT(nullptr) {
  initializeAMDGPUPrintfRuntimeBindingPass(*PassRegistry::getPassRegistry());
}

void AMDGPUPrintfRuntimeBinding::getConversionSpecifiers(
    SmallVectorImpl<char> &OpConvSpecifiers, StringRef Fmt,
    size_t NumOps) const {
  // not all format characters are collected.
  // At this time the format characters of interest
  // are %p and %s, which use to know if we
  // are either storing a literal string or a
  // pointer to the printf buffer.
  static const char ConvSpecifiers[] = "cdieEfgGaosuxXp";
  size_t CurFmtSpecifierIdx = 0;
  size_t PrevFmtSpecifierIdx = 0;

  while ((CurFmtSpecifierIdx = Fmt.find_first_of(
              ConvSpecifiers, CurFmtSpecifierIdx)) != StringRef::npos) {
    bool ArgDump = false;
    StringRef CurFmt = Fmt.substr(PrevFmtSpecifierIdx,
                                  CurFmtSpecifierIdx - PrevFmtSpecifierIdx);
    size_t pTag = CurFmt.find_last_of("%");
    if (pTag != StringRef::npos) {
      ArgDump = true;
      while (pTag && CurFmt[--pTag] == '%') {
        ArgDump = !ArgDump;
      }
    }

    if (ArgDump)
      OpConvSpecifiers.push_back(Fmt[CurFmtSpecifierIdx]);

    PrevFmtSpecifierIdx = ++CurFmtSpecifierIdx;
  }
}

bool AMDGPUPrintfRuntimeBinding::shouldPrintAsStr(char Specifier,
                                                  Type *OpType) const {
  if (Specifier != 's')
    return false;
  const PointerType *PT = dyn_cast<PointerType>(OpType);
  if (!PT || PT->getAddressSpace() != AMDGPUAS::CONSTANT_ADDRESS)
    return false;
  Type *ElemType = PT->getContainedType(0);
  if (ElemType->getTypeID() != Type::IntegerTyID)
    return false;
  IntegerType *ElemIType = cast<IntegerType>(ElemType);
  return ElemIType->getBitWidth() == 8;
}

bool AMDGPUPrintfRuntimeBinding::lowerPrintfForGpu(
    Module &M, function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {
  LLVMContext &Ctx = M.getContext();
  IRBuilder<> Builder(Ctx);
  Type *I32Ty = Type::getInt32Ty(Ctx);
  unsigned UniqID = 0;
  // NB: This is important for this string size to be divizable by 4
  const char NonLiteralStr[4] = "???";

  for (auto CI : Printfs) {
    unsigned NumOps = CI->getNumArgOperands();

    SmallString<16> OpConvSpecifiers;
    Value *Op = CI->getArgOperand(0);

    if (auto LI = dyn_cast<LoadInst>(Op)) {
      Op = LI->getPointerOperand();
      for (auto Use : Op->users()) {
        if (auto SI = dyn_cast<StoreInst>(Use)) {
          Op = SI->getValueOperand();
          break;
        }
      }
    }

    if (auto I = dyn_cast<Instruction>(Op)) {
      Value *Op_simplified = simplify(I, &GetTLI(*I->getFunction()));
      if (Op_simplified)
        Op = Op_simplified;
    }

    ConstantExpr *ConstExpr = dyn_cast<ConstantExpr>(Op);

    if (ConstExpr) {
      GlobalVariable *GVar = dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));

      StringRef Str("unknown");
      if (GVar && GVar->hasInitializer()) {
        auto Init = GVar->getInitializer();
        if (auto CA = dyn_cast<ConstantDataArray>(Init)) {
          if (CA->isString())
            Str = CA->getAsCString();
        } else if (isa<ConstantAggregateZero>(Init)) {
          Str = "";
        }
        //
        // we need this call to ascertain
        // that we are printing a string
        // or a pointer. It takes out the
        // specifiers and fills up the first
        // arg
        getConversionSpecifiers(OpConvSpecifiers, Str, NumOps - 1);
      }
      // Add metadata for the string
      std::string AStreamHolder;
      raw_string_ostream Sizes(AStreamHolder);
      int Sum = DWORD_ALIGN;
      Sizes << CI->getNumArgOperands() - 1;
      Sizes << ':';
      for (unsigned ArgCount = 1; ArgCount < CI->getNumArgOperands() &&
                                  ArgCount <= OpConvSpecifiers.size();
           ArgCount++) {
        Value *Arg = CI->getArgOperand(ArgCount);
        Type *ArgType = Arg->getType();
        unsigned ArgSize = TD->getTypeAllocSizeInBits(ArgType);
        ArgSize = ArgSize / 8;
        //
        // ArgSize by design should be a multiple of DWORD_ALIGN,
        // expand the arguments that do not follow this rule.
        //
        if (ArgSize % DWORD_ALIGN != 0) {
          llvm::Type *ResType = llvm::Type::getInt32Ty(Ctx);
          VectorType *LLVMVecType = llvm::dyn_cast<llvm::VectorType>(ArgType);
          int NumElem = LLVMVecType ? LLVMVecType->getNumElements() : 1;
          if (LLVMVecType && NumElem > 1)
            ResType = llvm::VectorType::get(ResType, NumElem);
          Builder.SetInsertPoint(CI);
          Builder.SetCurrentDebugLocation(CI->getDebugLoc());
          if (OpConvSpecifiers[ArgCount - 1] == 'x' ||
              OpConvSpecifiers[ArgCount - 1] == 'X' ||
              OpConvSpecifiers[ArgCount - 1] == 'u' ||
              OpConvSpecifiers[ArgCount - 1] == 'o')
            Arg = Builder.CreateZExt(Arg, ResType);
          else
            Arg = Builder.CreateSExt(Arg, ResType);
          ArgType = Arg->getType();
          ArgSize = TD->getTypeAllocSizeInBits(ArgType);
          ArgSize = ArgSize / 8;
          CI->setOperand(ArgCount, Arg);
        }
        if (OpConvSpecifiers[ArgCount - 1] == 'f') {
          ConstantFP *FpCons = dyn_cast<ConstantFP>(Arg);
          if (FpCons)
            ArgSize = 4;
          else {
            FPExtInst *FpExt = dyn_cast<FPExtInst>(Arg);
            if (FpExt && FpExt->getType()->isDoubleTy() &&
                FpExt->getOperand(0)->getType()->isFloatTy())
              ArgSize = 4;
          }
        }
        if (shouldPrintAsStr(OpConvSpecifiers[ArgCount - 1], ArgType)) {
          if (ConstantExpr *ConstExpr = dyn_cast<ConstantExpr>(Arg)) {
            GlobalVariable *GV =
                dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));
            if (GV && GV->hasInitializer()) {
              Constant *Init = GV->getInitializer();
              ConstantDataArray *CA = dyn_cast<ConstantDataArray>(Init);
              if (Init->isZeroValue() || CA->isString()) {
                size_t SizeStr = Init->isZeroValue()
                                     ? 1
                                     : (strlen(CA->getAsCString().data()) + 1);
                size_t Rem = SizeStr % DWORD_ALIGN;
                size_t NSizeStr = 0;
                LLVM_DEBUG(dbgs() << "Printf string original size = " << SizeStr
                                  << '\n');
                if (Rem) {
                  NSizeStr = SizeStr + (DWORD_ALIGN - Rem);
                } else {
                  NSizeStr = SizeStr;
                }
                ArgSize = NSizeStr;
              }
            } else {
              ArgSize = sizeof(NonLiteralStr);
            }
          } else {
            ArgSize = sizeof(NonLiteralStr);
          }
        }
        LLVM_DEBUG(dbgs() << "Printf ArgSize (in buffer) = " << ArgSize
                          << " for type: " << *ArgType << '\n');
        Sizes << ArgSize << ':';
        Sum += ArgSize;
      }
      LLVM_DEBUG(dbgs() << "Printf format string in source = " << Str.str()
                        << '\n');
      for (size_t I = 0; I < Str.size(); ++I) {
        // Rest of the C escape sequences (e.g. \') are handled correctly
        // by the MDParser
        switch (Str[I]) {
        case '\a':
          Sizes << "\\a";
          break;
        case '\b':
          Sizes << "\\b";
          break;
        case '\f':
          Sizes << "\\f";
          break;
        case '\n':
          Sizes << "\\n";
          break;
        case '\r':
          Sizes << "\\r";
          break;
        case '\v':
          Sizes << "\\v";
          break;
        case ':':
          // ':' cannot be scanned by Flex, as it is defined as a delimiter
          // Replace it with it's octal representation \72
          Sizes << "\\72";
          break;
        default:
          Sizes << Str[I];
          break;
        }
      }

      // Insert the printf_alloc call
      Builder.SetInsertPoint(CI);
      Builder.SetCurrentDebugLocation(CI->getDebugLoc());

      AttributeList Attr = AttributeList::get(Ctx, AttributeList::FunctionIndex,
                                              Attribute::NoUnwind);

      Type *SizetTy = Type::getInt32Ty(Ctx);

      Type *Tys_alloc[1] = {SizetTy};
      Type *I8Ptr = PointerType::get(Type::getInt8Ty(Ctx), 1);
      FunctionType *FTy_alloc = FunctionType::get(I8Ptr, Tys_alloc, false);
      FunctionCallee PrintfAllocFn =
          M.getOrInsertFunction(StringRef("__printf_alloc"), FTy_alloc, Attr);

      LLVM_DEBUG(dbgs() << "Printf metadata = " << Sizes.str() << '\n');
      std::string fmtstr = itostr(++UniqID) + ":" + Sizes.str().c_str();
      MDString *fmtStrArray = MDString::get(Ctx, fmtstr);

      // Instead of creating global variables, the
      // printf format strings are extracted
      // and passed as metadata. This avoids
      // polluting llvm's symbol tables in this module.
      // Metadata is going to be extracted
      // by the backend passes and inserted
      // into the OpenCL binary as appropriate.
      StringRef amd("llvm.printf.fmts");
      NamedMDNode *metaD = M.getOrInsertNamedMetadata(amd);
      MDNode *myMD = MDNode::get(Ctx, fmtStrArray);
      metaD->addOperand(myMD);
      Value *sumC = ConstantInt::get(SizetTy, Sum, false);
      SmallVector<Value *, 1> alloc_args;
      alloc_args.push_back(sumC);
      CallInst *pcall =
          CallInst::Create(PrintfAllocFn, alloc_args, "printf_alloc_fn", CI);

      //
      // Insert code to split basicblock with a
      // piece of hammock code.
      // basicblock splits after buffer overflow check
      //
      ConstantPointerNull *zeroIntPtr =
          ConstantPointerNull::get(PointerType::get(Type::getInt8Ty(Ctx), 1));
      ICmpInst *cmp =
          dyn_cast<ICmpInst>(Builder.CreateICmpNE(pcall, zeroIntPtr, ""));
      if (!CI->use_empty()) {
        Value *result =
            Builder.CreateSExt(Builder.CreateNot(cmp), I32Ty, "printf_res");
        CI->replaceAllUsesWith(result);
      }
      SplitBlock(CI->getParent(), cmp);
      Instruction *Brnch =
          SplitBlockAndInsertIfThen(cmp, cmp->getNextNode(), false);

      Builder.SetInsertPoint(Brnch);

      // store unique printf id in the buffer
      //
      SmallVector<Value *, 1> ZeroIdxList;
      ConstantInt *zeroInt =
          ConstantInt::get(Ctx, APInt(32, StringRef("0"), 10));
      ZeroIdxList.push_back(zeroInt);

      GetElementPtrInst *BufferIdx =
          dyn_cast<GetElementPtrInst>(GetElementPtrInst::Create(
              nullptr, pcall, ZeroIdxList, "PrintBuffID", Brnch));

      Type *idPointer = PointerType::get(I32Ty, AMDGPUAS::GLOBAL_ADDRESS);
      Value *id_gep_cast =
          new BitCastInst(BufferIdx, idPointer, "PrintBuffIdCast", Brnch);

      StoreInst *stbuff =
          new StoreInst(ConstantInt::get(I32Ty, UniqID), id_gep_cast);
      stbuff->insertBefore(Brnch); // to Remove unused variable warning

      SmallVector<Value *, 2> FourthIdxList;
      ConstantInt *fourInt =
          ConstantInt::get(Ctx, APInt(32, StringRef("4"), 10));

      FourthIdxList.push_back(fourInt); // 1st 4 bytes hold the printf_id
      // the following GEP is the buffer pointer
      BufferIdx = cast<GetElementPtrInst>(GetElementPtrInst::Create(
          nullptr, pcall, FourthIdxList, "PrintBuffGep", Brnch));

      Type *Int32Ty = Type::getInt32Ty(Ctx);
      Type *Int64Ty = Type::getInt64Ty(Ctx);
      for (unsigned ArgCount = 1; ArgCount < CI->getNumArgOperands() &&
                                  ArgCount <= OpConvSpecifiers.size();
           ArgCount++) {
        Value *Arg = CI->getArgOperand(ArgCount);
        Type *ArgType = Arg->getType();
        SmallVector<Value *, 32> WhatToStore;
        if (ArgType->isFPOrFPVectorTy() &&
            (ArgType->getTypeID() != Type::VectorTyID)) {
          Type *IType = (ArgType->isFloatTy()) ? Int32Ty : Int64Ty;
          if (OpConvSpecifiers[ArgCount - 1] == 'f') {
            ConstantFP *fpCons = dyn_cast<ConstantFP>(Arg);
            if (fpCons) {
              APFloat Val(fpCons->getValueAPF());
              bool Lost = false;
              Val.convert(APFloat::IEEEsingle(), APFloat::rmNearestTiesToEven,
                          &Lost);
              Arg = ConstantFP::get(Ctx, Val);
              IType = Int32Ty;
            } else {
              FPExtInst *FpExt = dyn_cast<FPExtInst>(Arg);
              if (FpExt && FpExt->getType()->isDoubleTy() &&
                  FpExt->getOperand(0)->getType()->isFloatTy()) {
                Arg = FpExt->getOperand(0);
                IType = Int32Ty;
              }
            }
          }
          Arg = new BitCastInst(Arg, IType, "PrintArgFP", Brnch);
          WhatToStore.push_back(Arg);
        } else if (ArgType->getTypeID() == Type::PointerTyID) {
          if (shouldPrintAsStr(OpConvSpecifiers[ArgCount - 1], ArgType)) {
            const char *S = NonLiteralStr;
            if (ConstantExpr *ConstExpr = dyn_cast<ConstantExpr>(Arg)) {
              GlobalVariable *GV =
                  dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));
              if (GV && GV->hasInitializer()) {
                Constant *Init = GV->getInitializer();
                ConstantDataArray *CA = dyn_cast<ConstantDataArray>(Init);
                if (Init->isZeroValue() || CA->isString()) {
                  S = Init->isZeroValue() ? "" : CA->getAsCString().data();
                }
              }
            }
            size_t SizeStr = strlen(S) + 1;
            size_t Rem = SizeStr % DWORD_ALIGN;
            size_t NSizeStr = 0;
            if (Rem) {
              NSizeStr = SizeStr + (DWORD_ALIGN - Rem);
            } else {
              NSizeStr = SizeStr;
            }
            if (S[0]) {
              char *MyNewStr = new char[NSizeStr]();
              strcpy(MyNewStr, S);
              int NumInts = NSizeStr / 4;
              int CharC = 0;
              while (NumInts) {
                int ANum = *(int *)(MyNewStr + CharC);
                CharC += 4;
                NumInts--;
                Value *ANumV = ConstantInt::get(Int32Ty, ANum, false);
                WhatToStore.push_back(ANumV);
              }
              delete[] MyNewStr;
            } else {
              // Empty string, give a hint to RT it is no NULL
              Value *ANumV = ConstantInt::get(Int32Ty, 0xFFFFFF00, false);
              WhatToStore.push_back(ANumV);
            }
          } else {
            uint64_t Size = TD->getTypeAllocSizeInBits(ArgType);
            assert((Size == 32 || Size == 64) && "unsupported size");
            Type *DstType = (Size == 32) ? Int32Ty : Int64Ty;
            Arg = new PtrToIntInst(Arg, DstType, "PrintArgPtr", Brnch);
            WhatToStore.push_back(Arg);
          }
        } else if (ArgType->getTypeID() == Type::VectorTyID) {
          Type *IType = NULL;
          uint32_t EleCount = cast<VectorType>(ArgType)->getNumElements();
          uint32_t EleSize = ArgType->getScalarSizeInBits();
          uint32_t TotalSize = EleCount * EleSize;
          if (EleCount == 3) {
            IntegerType *Int32Ty = Type::getInt32Ty(ArgType->getContext());
            Constant *Indices[4] = {
                ConstantInt::get(Int32Ty, 0), ConstantInt::get(Int32Ty, 1),
                ConstantInt::get(Int32Ty, 2), ConstantInt::get(Int32Ty, 2)};
            Constant *Mask = ConstantVector::get(Indices);
            ShuffleVectorInst *Shuffle = new ShuffleVectorInst(Arg, Arg, Mask);
            Shuffle->insertBefore(Brnch);
            Arg = Shuffle;
            ArgType = Arg->getType();
            TotalSize += EleSize;
          }
          switch (EleSize) {
          default:
            EleCount = TotalSize / 64;
            IType = dyn_cast<Type>(Type::getInt64Ty(ArgType->getContext()));
            break;
          case 8:
            if (EleCount >= 8) {
              EleCount = TotalSize / 64;
              IType = dyn_cast<Type>(Type::getInt64Ty(ArgType->getContext()));
            } else if (EleCount >= 3) {
              EleCount = 1;
              IType = dyn_cast<Type>(Type::getInt32Ty(ArgType->getContext()));
            } else {
              EleCount = 1;
              IType = dyn_cast<Type>(Type::getInt16Ty(ArgType->getContext()));
            }
            break;
          case 16:
            if (EleCount >= 3) {
              EleCount = TotalSize / 64;
              IType = dyn_cast<Type>(Type::getInt64Ty(ArgType->getContext()));
            } else {
              EleCount = 1;
              IType = dyn_cast<Type>(Type::getInt32Ty(ArgType->getContext()));
            }
            break;
          }
          if (EleCount > 1) {
            IType = dyn_cast<Type>(VectorType::get(IType, EleCount));
          }
          Arg = new BitCastInst(Arg, IType, "PrintArgVect", Brnch);
          WhatToStore.push_back(Arg);
        } else {
          WhatToStore.push_back(Arg);
        }
        for (unsigned I = 0, E = WhatToStore.size(); I != E; ++I) {
          Value *TheBtCast = WhatToStore[I];
          unsigned ArgSize =
              TD->getTypeAllocSizeInBits(TheBtCast->getType()) / 8;
          SmallVector<Value *, 1> BuffOffset;
          BuffOffset.push_back(ConstantInt::get(I32Ty, ArgSize));

          Type *ArgPointer = PointerType::get(TheBtCast->getType(), 1);
          Value *CastedGEP =
              new BitCastInst(BufferIdx, ArgPointer, "PrintBuffPtrCast", Brnch);
          StoreInst *StBuff = new StoreInst(TheBtCast, CastedGEP, Brnch);
          LLVM_DEBUG(dbgs() << "inserting store to printf buffer:\n"
                            << *StBuff << '\n');
          (void)StBuff;
          if (I + 1 == E && ArgCount + 1 == CI->getNumArgOperands())
            break;
          BufferIdx = dyn_cast<GetElementPtrInst>(GetElementPtrInst::Create(
              nullptr, BufferIdx, BuffOffset, "PrintBuffNextPtr", Brnch));
          LLVM_DEBUG(dbgs() << "inserting gep to the printf buffer:\n"
                            << *BufferIdx << '\n');
        }
      }
    }
  }

  // erase the printf calls
  for (auto CI : Printfs)
    CI->eraseFromParent();

  Printfs.clear();
  return true;
}

bool AMDGPUPrintfRuntimeBinding::runOnModule(Module &M) {
  Triple TT(M.getTargetTriple());
  if (TT.getArch() == Triple::r600)
    return false;

  auto PrintfFunction = M.getFunction("printf");
  if (!PrintfFunction)
    return false;

  for (auto &U : PrintfFunction->uses()) {
    if (auto *CI = dyn_cast<CallInst>(U.getUser())) {
      if (CI->isCallee(&U))
        Printfs.push_back(CI);
    }
  }

  if (Printfs.empty())
    return false;

  TD = &M.getDataLayout();
  auto DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
  DT = DTWP ? &DTWP->getDomTree() : nullptr;
  auto GetTLI = [this](Function &F) -> TargetLibraryInfo & {
    return this->getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
  };

  return lowerPrintfForGpu(M, GetTLI);
}