xref: /llvm-project/llvm/lib/Target/AMDGPU/AMDGPUPrintfRuntimeBinding.cpp (revision 2de9b107facc2a0320e081787e8dfae43be83008)
1 //=== AMDGPUPrintfRuntimeBinding.cpp - OpenCL printf implementation -------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 // \file
9 //
10 // The pass bind printfs to a kernel arg pointer that will be bound to a buffer
11 // later by the runtime.
12 //
13 // This pass traverses the functions in the module and converts
14 // each call to printf to a sequence of operations that
15 // store the following into the printf buffer:
16 // - format string (passed as a module's metadata unique ID)
17 // - bitwise copies of printf arguments
18 // The backend passes will need to store metadata in the kernel
19 //===----------------------------------------------------------------------===//
20 
21 #include "AMDGPU.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/StringExtras.h"
24 #include "llvm/ADT/Triple.h"
25 #include "llvm/Analysis/InstructionSimplify.h"
26 #include "llvm/Analysis/TargetLibraryInfo.h"
27 #include "llvm/CodeGen/Passes.h"
28 #include "llvm/IR/Constants.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Dominators.h"
31 #include "llvm/IR/GlobalVariable.h"
32 #include "llvm/IR/IRBuilder.h"
33 #include "llvm/IR/InstVisitor.h"
34 #include "llvm/IR/Instructions.h"
35 #include "llvm/IR/Module.h"
36 #include "llvm/IR/Type.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
41 using namespace llvm;
42 
43 #define DEBUG_TYPE "printfToRuntime"
44 #define DWORD_ALIGN 4
45 
46 namespace {
47 class LLVM_LIBRARY_VISIBILITY AMDGPUPrintfRuntimeBinding final
48     : public ModulePass,
49       public InstVisitor<AMDGPUPrintfRuntimeBinding> {
50 
51 public:
52   static char ID;
53 
54   explicit AMDGPUPrintfRuntimeBinding();
55 
56   void visitCallSite(CallSite CS) {
57     Function *F = CS.getCalledFunction();
58     if (F && F->hasName() && F->getName() == "printf")
59       Printfs.push_back(CS.getInstruction());
60   }
61 
62 private:
63   bool runOnModule(Module &M) override;
64   void getConversionSpecifiers(SmallVectorImpl<char> &OpConvSpecifiers,
65                                StringRef fmt, size_t num_ops) const;
66 
67   bool shouldPrintAsStr(char Specifier, Type *OpType) const;
68   bool
69   lowerPrintfForGpu(Module &M,
70                     function_ref<const TargetLibraryInfo &(Function &)> GetTLI);
71 
72   void getAnalysisUsage(AnalysisUsage &AU) const override {
73     AU.addRequired<TargetLibraryInfoWrapperPass>();
74     AU.addRequired<DominatorTreeWrapperPass>();
75   }
76 
77   Value *simplify(Instruction *I, const TargetLibraryInfo *TLI) {
78     return SimplifyInstruction(I, {*TD, TLI, DT});
79   }
80 
81   const DataLayout *TD;
82   const DominatorTree *DT;
83   SmallVector<Value *, 32> Printfs;
84 };
85 } // namespace
86 
87 char AMDGPUPrintfRuntimeBinding::ID = 0;
88 
89 INITIALIZE_PASS_BEGIN(AMDGPUPrintfRuntimeBinding,
90                       "amdgpu-printf-runtime-binding", "AMDGPU Printf lowering",
91                       false, false)
92 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
93 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
94 INITIALIZE_PASS_END(AMDGPUPrintfRuntimeBinding, "amdgpu-printf-runtime-binding",
95                     "AMDGPU Printf lowering", false, false)
96 
97 char &llvm::AMDGPUPrintfRuntimeBindingID = AMDGPUPrintfRuntimeBinding::ID;
98 
99 namespace llvm {
100 ModulePass *createAMDGPUPrintfRuntimeBinding() {
101   return new AMDGPUPrintfRuntimeBinding();
102 }
103 } // namespace llvm
104 
105 AMDGPUPrintfRuntimeBinding::AMDGPUPrintfRuntimeBinding()
106     : ModulePass(ID), TD(nullptr), DT(nullptr) {
107   initializeAMDGPUPrintfRuntimeBindingPass(*PassRegistry::getPassRegistry());
108 }
109 
110 void AMDGPUPrintfRuntimeBinding::getConversionSpecifiers(
111     SmallVectorImpl<char> &OpConvSpecifiers, StringRef Fmt,
112     size_t NumOps) const {
113   // not all format characters are collected.
114   // At this time the format characters of interest
115   // are %p and %s, which use to know if we
116   // are either storing a literal string or a
117   // pointer to the printf buffer.
118   static const char ConvSpecifiers[] = "cdieEfgGaosuxXp";
119   size_t CurFmtSpecifierIdx = 0;
120   size_t PrevFmtSpecifierIdx = 0;
121 
122   while ((CurFmtSpecifierIdx = Fmt.find_first_of(
123               ConvSpecifiers, CurFmtSpecifierIdx)) != StringRef::npos) {
124     bool ArgDump = false;
125     StringRef CurFmt = Fmt.substr(PrevFmtSpecifierIdx,
126                                   CurFmtSpecifierIdx - PrevFmtSpecifierIdx);
127     size_t pTag = CurFmt.find_last_of("%");
128     if (pTag != StringRef::npos) {
129       ArgDump = true;
130       while (pTag && CurFmt[--pTag] == '%') {
131         ArgDump = !ArgDump;
132       }
133     }
134 
135     if (ArgDump)
136       OpConvSpecifiers.push_back(Fmt[CurFmtSpecifierIdx]);
137 
138     PrevFmtSpecifierIdx = ++CurFmtSpecifierIdx;
139   }
140 }
141 
142 bool AMDGPUPrintfRuntimeBinding::shouldPrintAsStr(char Specifier,
143                                                   Type *OpType) const {
144   if (Specifier != 's')
145     return false;
146   const PointerType *PT = dyn_cast<PointerType>(OpType);
147   if (!PT || PT->getAddressSpace() != AMDGPUAS::CONSTANT_ADDRESS)
148     return false;
149   Type *ElemType = PT->getContainedType(0);
150   if (ElemType->getTypeID() != Type::IntegerTyID)
151     return false;
152   IntegerType *ElemIType = cast<IntegerType>(ElemType);
153   return ElemIType->getBitWidth() == 8;
154 }
155 
156 bool AMDGPUPrintfRuntimeBinding::lowerPrintfForGpu(
157     Module &M, function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {
158   LLVMContext &Ctx = M.getContext();
159   IRBuilder<> Builder(Ctx);
160   Type *I32Ty = Type::getInt32Ty(Ctx);
161   unsigned UniqID = 0;
162   // NB: This is important for this string size to be divizable by 4
163   const char NonLiteralStr[4] = "???";
164 
165   for (auto P : Printfs) {
166     auto CI = cast<CallInst>(P);
167     unsigned NumOps = CI->getNumArgOperands();
168 
169     SmallString<16> OpConvSpecifiers;
170     Value *Op = CI->getArgOperand(0);
171 
172     if (auto LI = dyn_cast<LoadInst>(Op)) {
173       Op = LI->getPointerOperand();
174       for (auto Use : Op->users()) {
175         if (auto SI = dyn_cast<StoreInst>(Use)) {
176           Op = SI->getValueOperand();
177           break;
178         }
179       }
180     }
181 
182     if (auto I = dyn_cast<Instruction>(Op)) {
183       Value *Op_simplified = simplify(I, &GetTLI(*I->getFunction()));
184       if (Op_simplified)
185         Op = Op_simplified;
186     }
187 
188     ConstantExpr *ConstExpr = dyn_cast<ConstantExpr>(Op);
189 
190     if (ConstExpr) {
191       GlobalVariable *GVar = dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));
192 
193       StringRef Str("unknown");
194       if (GVar && GVar->hasInitializer()) {
195         auto Init = GVar->getInitializer();
196         if (auto CA = dyn_cast<ConstantDataArray>(Init)) {
197           if (CA->isString())
198             Str = CA->getAsCString();
199         } else if (isa<ConstantAggregateZero>(Init)) {
200           Str = "";
201         }
202         //
203         // we need this call to ascertain
204         // that we are printing a string
205         // or a pointer. It takes out the
206         // specifiers and fills up the first
207         // arg
208         getConversionSpecifiers(OpConvSpecifiers, Str, NumOps - 1);
209       }
210       // Add metadata for the string
211       std::string AStreamHolder;
212       raw_string_ostream Sizes(AStreamHolder);
213       int Sum = DWORD_ALIGN;
214       Sizes << CI->getNumArgOperands() - 1;
215       Sizes << ':';
216       for (unsigned ArgCount = 1; ArgCount < CI->getNumArgOperands() &&
217                                   ArgCount <= OpConvSpecifiers.size();
218            ArgCount++) {
219         Value *Arg = CI->getArgOperand(ArgCount);
220         Type *ArgType = Arg->getType();
221         unsigned ArgSize = TD->getTypeAllocSizeInBits(ArgType);
222         ArgSize = ArgSize / 8;
223         //
224         // ArgSize by design should be a multiple of DWORD_ALIGN,
225         // expand the arguments that do not follow this rule.
226         //
227         if (ArgSize % DWORD_ALIGN != 0) {
228           llvm::Type *ResType = llvm::Type::getInt32Ty(Ctx);
229           VectorType *LLVMVecType = llvm::dyn_cast<llvm::VectorType>(ArgType);
230           int NumElem = LLVMVecType ? LLVMVecType->getNumElements() : 1;
231           if (LLVMVecType && NumElem > 1)
232             ResType = llvm::VectorType::get(ResType, NumElem);
233           Builder.SetInsertPoint(CI);
234           Builder.SetCurrentDebugLocation(CI->getDebugLoc());
235           if (OpConvSpecifiers[ArgCount - 1] == 'x' ||
236               OpConvSpecifiers[ArgCount - 1] == 'X' ||
237               OpConvSpecifiers[ArgCount - 1] == 'u' ||
238               OpConvSpecifiers[ArgCount - 1] == 'o')
239             Arg = Builder.CreateZExt(Arg, ResType);
240           else
241             Arg = Builder.CreateSExt(Arg, ResType);
242           ArgType = Arg->getType();
243           ArgSize = TD->getTypeAllocSizeInBits(ArgType);
244           ArgSize = ArgSize / 8;
245           CI->setOperand(ArgCount, Arg);
246         }
247         if (OpConvSpecifiers[ArgCount - 1] == 'f') {
248           ConstantFP *FpCons = dyn_cast<ConstantFP>(Arg);
249           if (FpCons)
250             ArgSize = 4;
251           else {
252             FPExtInst *FpExt = dyn_cast<FPExtInst>(Arg);
253             if (FpExt && FpExt->getType()->isDoubleTy() &&
254                 FpExt->getOperand(0)->getType()->isFloatTy())
255               ArgSize = 4;
256           }
257         }
258         if (shouldPrintAsStr(OpConvSpecifiers[ArgCount - 1], ArgType)) {
259           if (ConstantExpr *ConstExpr = dyn_cast<ConstantExpr>(Arg)) {
260             GlobalVariable *GV =
261                 dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));
262             if (GV && GV->hasInitializer()) {
263               Constant *Init = GV->getInitializer();
264               ConstantDataArray *CA = dyn_cast<ConstantDataArray>(Init);
265               if (Init->isZeroValue() || CA->isString()) {
266                 size_t SizeStr = Init->isZeroValue()
267                                      ? 1
268                                      : (strlen(CA->getAsCString().data()) + 1);
269                 size_t Rem = SizeStr % DWORD_ALIGN;
270                 size_t NSizeStr = 0;
271                 LLVM_DEBUG(dbgs() << "Printf string original size = " << SizeStr
272                                   << '\n');
273                 if (Rem) {
274                   NSizeStr = SizeStr + (DWORD_ALIGN - Rem);
275                 } else {
276                   NSizeStr = SizeStr;
277                 }
278                 ArgSize = NSizeStr;
279               }
280             } else {
281               ArgSize = sizeof(NonLiteralStr);
282             }
283           } else {
284             ArgSize = sizeof(NonLiteralStr);
285           }
286         }
287         LLVM_DEBUG(dbgs() << "Printf ArgSize (in buffer) = " << ArgSize
288                           << " for type: " << *ArgType << '\n');
289         Sizes << ArgSize << ':';
290         Sum += ArgSize;
291       }
292       LLVM_DEBUG(dbgs() << "Printf format string in source = " << Str.str()
293                         << '\n');
294       for (size_t I = 0; I < Str.size(); ++I) {
295         // Rest of the C escape sequences (e.g. \') are handled correctly
296         // by the MDParser
297         switch (Str[I]) {
298         case '\a':
299           Sizes << "\\a";
300           break;
301         case '\b':
302           Sizes << "\\b";
303           break;
304         case '\f':
305           Sizes << "\\f";
306           break;
307         case '\n':
308           Sizes << "\\n";
309           break;
310         case '\r':
311           Sizes << "\\r";
312           break;
313         case '\v':
314           Sizes << "\\v";
315           break;
316         case ':':
317           // ':' cannot be scanned by Flex, as it is defined as a delimiter
318           // Replace it with it's octal representation \72
319           Sizes << "\\72";
320           break;
321         default:
322           Sizes << Str[I];
323           break;
324         }
325       }
326 
327       // Insert the printf_alloc call
328       Builder.SetInsertPoint(CI);
329       Builder.SetCurrentDebugLocation(CI->getDebugLoc());
330 
331       AttributeList Attr = AttributeList::get(Ctx, AttributeList::FunctionIndex,
332                                               Attribute::NoUnwind);
333 
334       Type *SizetTy = Type::getInt32Ty(Ctx);
335 
336       Type *Tys_alloc[1] = {SizetTy};
337       Type *I8Ptr = PointerType::get(Type::getInt8Ty(Ctx), 1);
338       FunctionType *FTy_alloc = FunctionType::get(I8Ptr, Tys_alloc, false);
339       FunctionCallee PrintfAllocFn =
340           M.getOrInsertFunction(StringRef("__printf_alloc"), FTy_alloc, Attr);
341 
342       LLVM_DEBUG(dbgs() << "Printf metadata = " << Sizes.str() << '\n');
343       std::string fmtstr = itostr(++UniqID) + ":" + Sizes.str().c_str();
344       MDString *fmtStrArray = MDString::get(Ctx, fmtstr);
345 
346       // Instead of creating global variables, the
347       // printf format strings are extracted
348       // and passed as metadata. This avoids
349       // polluting llvm's symbol tables in this module.
350       // Metadata is going to be extracted
351       // by the backend passes and inserted
352       // into the OpenCL binary as appropriate.
353       StringRef amd("llvm.printf.fmts");
354       NamedMDNode *metaD = M.getOrInsertNamedMetadata(amd);
355       MDNode *myMD = MDNode::get(Ctx, fmtStrArray);
356       metaD->addOperand(myMD);
357       Value *sumC = ConstantInt::get(SizetTy, Sum, false);
358       SmallVector<Value *, 1> alloc_args;
359       alloc_args.push_back(sumC);
360       CallInst *pcall =
361           CallInst::Create(PrintfAllocFn, alloc_args, "printf_alloc_fn", CI);
362 
363       //
364       // Insert code to split basicblock with a
365       // piece of hammock code.
366       // basicblock splits after buffer overflow check
367       //
368       ConstantPointerNull *zeroIntPtr =
369           ConstantPointerNull::get(PointerType::get(Type::getInt8Ty(Ctx), 1));
370       ICmpInst *cmp =
371           dyn_cast<ICmpInst>(Builder.CreateICmpNE(pcall, zeroIntPtr, ""));
372       if (!CI->use_empty()) {
373         Value *result =
374             Builder.CreateSExt(Builder.CreateNot(cmp), I32Ty, "printf_res");
375         CI->replaceAllUsesWith(result);
376       }
377       SplitBlock(CI->getParent(), cmp);
378       Instruction *Brnch =
379           SplitBlockAndInsertIfThen(cmp, cmp->getNextNode(), false);
380 
381       Builder.SetInsertPoint(Brnch);
382 
383       // store unique printf id in the buffer
384       //
385       SmallVector<Value *, 1> ZeroIdxList;
386       ConstantInt *zeroInt =
387           ConstantInt::get(Ctx, APInt(32, StringRef("0"), 10));
388       ZeroIdxList.push_back(zeroInt);
389 
390       GetElementPtrInst *BufferIdx =
391           dyn_cast<GetElementPtrInst>(GetElementPtrInst::Create(
392               nullptr, pcall, ZeroIdxList, "PrintBuffID", Brnch));
393 
394       Type *idPointer = PointerType::get(I32Ty, AMDGPUAS::GLOBAL_ADDRESS);
395       Value *id_gep_cast =
396           new BitCastInst(BufferIdx, idPointer, "PrintBuffIdCast", Brnch);
397 
398       StoreInst *stbuff =
399           new StoreInst(ConstantInt::get(I32Ty, UniqID), id_gep_cast);
400       stbuff->insertBefore(Brnch); // to Remove unused variable warning
401 
402       SmallVector<Value *, 2> FourthIdxList;
403       ConstantInt *fourInt =
404           ConstantInt::get(Ctx, APInt(32, StringRef("4"), 10));
405 
406       FourthIdxList.push_back(fourInt); // 1st 4 bytes hold the printf_id
407       // the following GEP is the buffer pointer
408       BufferIdx = cast<GetElementPtrInst>(GetElementPtrInst::Create(
409           nullptr, pcall, FourthIdxList, "PrintBuffGep", Brnch));
410 
411       Type *Int32Ty = Type::getInt32Ty(Ctx);
412       Type *Int64Ty = Type::getInt64Ty(Ctx);
413       for (unsigned ArgCount = 1; ArgCount < CI->getNumArgOperands() &&
414                                   ArgCount <= OpConvSpecifiers.size();
415            ArgCount++) {
416         Value *Arg = CI->getArgOperand(ArgCount);
417         Type *ArgType = Arg->getType();
418         SmallVector<Value *, 32> WhatToStore;
419         if (ArgType->isFPOrFPVectorTy() &&
420             (ArgType->getTypeID() != Type::VectorTyID)) {
421           Type *IType = (ArgType->isFloatTy()) ? Int32Ty : Int64Ty;
422           if (OpConvSpecifiers[ArgCount - 1] == 'f') {
423             ConstantFP *fpCons = dyn_cast<ConstantFP>(Arg);
424             if (fpCons) {
425               APFloat Val(fpCons->getValueAPF());
426               bool Lost = false;
427               Val.convert(APFloat::IEEEsingle(), APFloat::rmNearestTiesToEven,
428                           &Lost);
429               Arg = ConstantFP::get(Ctx, Val);
430               IType = Int32Ty;
431             } else {
432               FPExtInst *FpExt = dyn_cast<FPExtInst>(Arg);
433               if (FpExt && FpExt->getType()->isDoubleTy() &&
434                   FpExt->getOperand(0)->getType()->isFloatTy()) {
435                 Arg = FpExt->getOperand(0);
436                 IType = Int32Ty;
437               }
438             }
439           }
440           Arg = new BitCastInst(Arg, IType, "PrintArgFP", Brnch);
441           WhatToStore.push_back(Arg);
442         } else if (ArgType->getTypeID() == Type::PointerTyID) {
443           if (shouldPrintAsStr(OpConvSpecifiers[ArgCount - 1], ArgType)) {
444             const char *S = NonLiteralStr;
445             if (ConstantExpr *ConstExpr = dyn_cast<ConstantExpr>(Arg)) {
446               GlobalVariable *GV =
447                   dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));
448               if (GV && GV->hasInitializer()) {
449                 Constant *Init = GV->getInitializer();
450                 ConstantDataArray *CA = dyn_cast<ConstantDataArray>(Init);
451                 if (Init->isZeroValue() || CA->isString()) {
452                   S = Init->isZeroValue() ? "" : CA->getAsCString().data();
453                 }
454               }
455             }
456             size_t SizeStr = strlen(S) + 1;
457             size_t Rem = SizeStr % DWORD_ALIGN;
458             size_t NSizeStr = 0;
459             if (Rem) {
460               NSizeStr = SizeStr + (DWORD_ALIGN - Rem);
461             } else {
462               NSizeStr = SizeStr;
463             }
464             if (S[0]) {
465               char *MyNewStr = new char[NSizeStr]();
466               strcpy(MyNewStr, S);
467               int NumInts = NSizeStr / 4;
468               int CharC = 0;
469               while (NumInts) {
470                 int ANum = *(int *)(MyNewStr + CharC);
471                 CharC += 4;
472                 NumInts--;
473                 Value *ANumV = ConstantInt::get(Int32Ty, ANum, false);
474                 WhatToStore.push_back(ANumV);
475               }
476               delete[] MyNewStr;
477             } else {
478               // Empty string, give a hint to RT it is no NULL
479               Value *ANumV = ConstantInt::get(Int32Ty, 0xFFFFFF00, false);
480               WhatToStore.push_back(ANumV);
481             }
482           } else {
483             uint64_t Size = TD->getTypeAllocSizeInBits(ArgType);
484             assert((Size == 32 || Size == 64) && "unsupported size");
485             Type *DstType = (Size == 32) ? Int32Ty : Int64Ty;
486             Arg = new PtrToIntInst(Arg, DstType, "PrintArgPtr", Brnch);
487             WhatToStore.push_back(Arg);
488           }
489         } else if (ArgType->getTypeID() == Type::VectorTyID) {
490           Type *IType = NULL;
491           uint32_t EleCount = cast<VectorType>(ArgType)->getNumElements();
492           uint32_t EleSize = ArgType->getScalarSizeInBits();
493           uint32_t TotalSize = EleCount * EleSize;
494           if (EleCount == 3) {
495             IntegerType *Int32Ty = Type::getInt32Ty(ArgType->getContext());
496             Constant *Indices[4] = {
497                 ConstantInt::get(Int32Ty, 0), ConstantInt::get(Int32Ty, 1),
498                 ConstantInt::get(Int32Ty, 2), ConstantInt::get(Int32Ty, 2)};
499             Constant *Mask = ConstantVector::get(Indices);
500             ShuffleVectorInst *Shuffle = new ShuffleVectorInst(Arg, Arg, Mask);
501             Shuffle->insertBefore(Brnch);
502             Arg = Shuffle;
503             ArgType = Arg->getType();
504             TotalSize += EleSize;
505           }
506           switch (EleSize) {
507           default:
508             EleCount = TotalSize / 64;
509             IType = dyn_cast<Type>(Type::getInt64Ty(ArgType->getContext()));
510             break;
511           case 8:
512             if (EleCount >= 8) {
513               EleCount = TotalSize / 64;
514               IType = dyn_cast<Type>(Type::getInt64Ty(ArgType->getContext()));
515             } else if (EleCount >= 3) {
516               EleCount = 1;
517               IType = dyn_cast<Type>(Type::getInt32Ty(ArgType->getContext()));
518             } else {
519               EleCount = 1;
520               IType = dyn_cast<Type>(Type::getInt16Ty(ArgType->getContext()));
521             }
522             break;
523           case 16:
524             if (EleCount >= 3) {
525               EleCount = TotalSize / 64;
526               IType = dyn_cast<Type>(Type::getInt64Ty(ArgType->getContext()));
527             } else {
528               EleCount = 1;
529               IType = dyn_cast<Type>(Type::getInt32Ty(ArgType->getContext()));
530             }
531             break;
532           }
533           if (EleCount > 1) {
534             IType = dyn_cast<Type>(VectorType::get(IType, EleCount));
535           }
536           Arg = new BitCastInst(Arg, IType, "PrintArgVect", Brnch);
537           WhatToStore.push_back(Arg);
538         } else {
539           WhatToStore.push_back(Arg);
540         }
541         for (unsigned I = 0, E = WhatToStore.size(); I != E; ++I) {
542           Value *TheBtCast = WhatToStore[I];
543           unsigned ArgSize =
544               TD->getTypeAllocSizeInBits(TheBtCast->getType()) / 8;
545           SmallVector<Value *, 1> BuffOffset;
546           BuffOffset.push_back(ConstantInt::get(I32Ty, ArgSize));
547 
548           Type *ArgPointer = PointerType::get(TheBtCast->getType(), 1);
549           Value *CastedGEP =
550               new BitCastInst(BufferIdx, ArgPointer, "PrintBuffPtrCast", Brnch);
551           StoreInst *StBuff = new StoreInst(TheBtCast, CastedGEP, Brnch);
552           LLVM_DEBUG(dbgs() << "inserting store to printf buffer:\n"
553                             << *StBuff << '\n');
554           (void)StBuff;
555           if (I + 1 == E && ArgCount + 1 == CI->getNumArgOperands())
556             break;
557           BufferIdx = dyn_cast<GetElementPtrInst>(GetElementPtrInst::Create(
558               nullptr, BufferIdx, BuffOffset, "PrintBuffNextPtr", Brnch));
559           LLVM_DEBUG(dbgs() << "inserting gep to the printf buffer:\n"
560                             << *BufferIdx << '\n');
561         }
562       }
563     }
564   }
565 
566   // erase the printf calls
567   for (auto P : Printfs) {
568     auto CI = cast<CallInst>(P);
569     CI->eraseFromParent();
570   }
571 
572   Printfs.clear();
573   return true;
574 }
575 
576 bool AMDGPUPrintfRuntimeBinding::runOnModule(Module &M) {
577   Triple TT(M.getTargetTriple());
578   if (TT.getArch() == Triple::r600)
579     return false;
580 
581   visit(M);
582 
583   if (Printfs.empty())
584     return false;
585 
586   TD = &M.getDataLayout();
587   auto DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
588   DT = DTWP ? &DTWP->getDomTree() : nullptr;
589   auto GetTLI = [this](Function &F) -> TargetLibraryInfo & {
590     return this->getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
591   };
592 
593   return lowerPrintfForGpu(M, GetTLI);
594 }
595