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llvm-mirror/lib/Target/AMDGPU/AMDGPUPrintfRuntimeBinding.cpp
Nikita Popov d73135cade [AMDGPU] Simplify GEP construction (NFC) 
Noticed while making a related change. This code was doing
something really peculiar: Creating an APInt by parsing a string.
And then creating a SmallVector with one element to create the
GEP.

Instead create the APInt from integers and directly pass the single
index to GetElementPtrInst::Create().
2021-07-08 21:21:43 +02:00

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//=== 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/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/InitializePasses.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;
#define DEBUG_TYPE "printfToRuntime"
#define DWORD_ALIGN 4
namespace {
class AMDGPUPrintfRuntimeBinding final : public ModulePass {
public:
static char ID;
explicit AMDGPUPrintfRuntimeBinding();
private:
bool runOnModule(Module &M) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.addRequired<DominatorTreeWrapperPass>();
}
};
class AMDGPUPrintfRuntimeBindingImpl {
public:
AMDGPUPrintfRuntimeBindingImpl(
function_ref<const DominatorTree &(Function &)> GetDT,
function_ref<const TargetLibraryInfo &(Function &)> GetTLI)
: GetDT(GetDT), GetTLI(GetTLI) {}
bool run(Module &M);
private:
void getConversionSpecifiers(SmallVectorImpl<char> &OpConvSpecifiers,
StringRef fmt, size_t num_ops) const;
bool shouldPrintAsStr(char Specifier, Type *OpType) const;
bool lowerPrintfForGpu(Module &M);
Value *simplify(Instruction *I, const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return SimplifyInstruction(I, {*TD, TLI, DT});
}
const DataLayout *TD;
function_ref<const DominatorTree &(Function &)> GetDT;
function_ref<const TargetLibraryInfo &(Function &)> GetTLI;
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) {
initializeAMDGPUPrintfRuntimeBindingPass(*PassRegistry::getPassRegistry());
}
void AMDGPUPrintfRuntimeBindingImpl::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 AMDGPUPrintfRuntimeBindingImpl::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 AMDGPUPrintfRuntimeBindingImpl::lowerPrintfForGpu(Module &M) {
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()), &GetDT(*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);
auto *LLVMVecType = llvm::dyn_cast<llvm::FixedVectorType>(ArgType);
int NumElem = LLVMVecType ? LLVMVecType->getNumElements() : 1;
if (LLVMVecType && NumElem > 1)
ResType = llvm::FixedVectorType::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 (auto *ConstExpr = dyn_cast<ConstantExpr>(Arg)) {
auto *GV = dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));
if (GV && GV->hasInitializer()) {
Constant *Init = GV->getInitializer();
bool IsZeroValue = Init->isZeroValue();
auto *CA = dyn_cast<ConstantDataArray>(Init);
if (IsZeroValue || (CA && CA->isString())) {
size_t SizeStr =
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 *I8Ty = Type::getInt8Ty(Ctx);
Type *I8Ptr = PointerType::get(I8Ty, 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(I8Ty, 1));
auto *cmp = 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
//
GetElementPtrInst *BufferIdx = GetElementPtrInst::Create(
I8Ty, pcall, ConstantInt::get(Ctx, APInt(32, 0)), "PrintBuffID",
Brnch);
Type *idPointer = PointerType::get(I32Ty, AMDGPUAS::GLOBAL_ADDRESS);
Value *id_gep_cast =
new BitCastInst(BufferIdx, idPointer, "PrintBuffIdCast", Brnch);
new StoreInst(ConstantInt::get(I32Ty, UniqID), id_gep_cast, Brnch);
// 1st 4 bytes hold the printf_id
// the following GEP is the buffer pointer
BufferIdx = GetElementPtrInst::Create(
I8Ty, pcall, ConstantInt::get(Ctx, APInt(32, 4)), "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() && !isa<VectorType>(ArgType)) {
Type *IType = (ArgType->isFloatTy()) ? Int32Ty : Int64Ty;
if (OpConvSpecifiers[ArgCount - 1] == 'f') {
if (auto *FpCons = dyn_cast<ConstantFP>(Arg)) {
APFloat Val(FpCons->getValueAPF());
bool Lost = false;
Val.convert(APFloat::IEEEsingle(), APFloat::rmNearestTiesToEven,
&Lost);
Arg = ConstantFP::get(Ctx, Val);
IType = Int32Ty;
} else if (auto *FpExt = dyn_cast<FPExtInst>(Arg)) {
if (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 (auto *ConstExpr = dyn_cast<ConstantExpr>(Arg)) {
auto *GV = dyn_cast<GlobalVariable>(ConstExpr->getOperand(0));
if (GV && GV->hasInitializer()) {
Constant *Init = GV->getInitializer();
bool IsZeroValue = Init->isZeroValue();
auto *CA = dyn_cast<ConstantDataArray>(Init);
if (IsZeroValue || (CA && CA->isString())) {
S = 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 (isa<FixedVectorType>(ArgType)) {
Type *IType = NULL;
uint32_t EleCount = cast<FixedVectorType>(ArgType)->getNumElements();
uint32_t EleSize = ArgType->getScalarSizeInBits();
uint32_t TotalSize = EleCount * EleSize;
if (EleCount == 3) {
ShuffleVectorInst *Shuffle =
new ShuffleVectorInst(Arg, Arg, ArrayRef<int>{0, 1, 2, 2});
Shuffle->insertBefore(Brnch);
Arg = Shuffle;
ArgType = Arg->getType();
TotalSize += EleSize;
}
switch (EleSize) {
default:
EleCount = TotalSize / 64;
IType = Type::getInt64Ty(ArgType->getContext());
break;
case 8:
if (EleCount >= 8) {
EleCount = TotalSize / 64;
IType = Type::getInt64Ty(ArgType->getContext());
} else if (EleCount >= 3) {
EleCount = 1;
IType = Type::getInt32Ty(ArgType->getContext());
} else {
EleCount = 1;
IType = Type::getInt16Ty(ArgType->getContext());
}
break;
case 16:
if (EleCount >= 3) {
EleCount = TotalSize / 64;
IType = Type::getInt64Ty(ArgType->getContext());
} else {
EleCount = 1;
IType = Type::getInt32Ty(ArgType->getContext());
}
break;
}
if (EleCount > 1) {
IType = FixedVectorType::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 = GetElementPtrInst::Create(I8Ty, 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 AMDGPUPrintfRuntimeBindingImpl::run(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;
if (auto HostcallFunction = M.getFunction("__ockl_hostcall_internal")) {
for (auto &U : HostcallFunction->uses()) {
if (auto *CI = dyn_cast<CallInst>(U.getUser())) {
M.getContext().emitError(
CI, "Cannot use both printf and hostcall in the same module");
}
}
}
TD = &M.getDataLayout();
return lowerPrintfForGpu(M);
}
bool AMDGPUPrintfRuntimeBinding::runOnModule(Module &M) {
auto GetDT = [this](Function &F) -> DominatorTree & {
return this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
};
auto GetTLI = [this](Function &F) -> TargetLibraryInfo & {
return this->getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
};
return AMDGPUPrintfRuntimeBindingImpl(GetDT, GetTLI).run(M);
}
PreservedAnalyses
AMDGPUPrintfRuntimeBindingPass::run(Module &M, ModuleAnalysisManager &AM) {
FunctionAnalysisManager &FAM =
AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
auto GetDT = [&FAM](Function &F) -> DominatorTree & {
return FAM.getResult<DominatorTreeAnalysis>(F);
};
auto GetTLI = [&FAM](Function &F) -> TargetLibraryInfo & {
return FAM.getResult<TargetLibraryAnalysis>(F);
};
bool Changed = AMDGPUPrintfRuntimeBindingImpl(GetDT, GetTLI).run(M);
return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
}
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