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llvm-project/llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp

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//===-- AMDGPUPromoteAlloca.cpp - Promote Allocas -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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/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/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.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 {
// 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;
MDNode *MaxWorkGroupSizeRange = nullptr;
AMDGPUAS AS;
// 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;
public:
static char ID;
AMDGPUPromoteAlloca(const TargetMachine *TM_ = nullptr) :
FunctionPass(ID), TM(TM_) {}
bool doInitialization(Module &M) override;
bool runOnFunction(Function &F) override;
StringRef getPassName() const override { return "AMDGPU Promote Alloca"; }
void handleAlloca(AllocaInst &I);
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
FunctionPass::getAnalysisUsage(AU);
}
};
} // end anonymous namespace
char AMDGPUPromoteAlloca::ID = 0;
INITIALIZE_TM_PASS(AMDGPUPromoteAlloca, DEBUG_TYPE,
"AMDGPU promote alloca to vector or LDS", false, false)
char &llvm::AMDGPUPromoteAllocaID = AMDGPUPromoteAlloca::ID;
bool AMDGPUPromoteAlloca::doInitialization(Module &M) {
if (!TM)
return false;
Mod = &M;
DL = &Mod->getDataLayout();
// The maximum workitem id.
//
// FIXME: Should get as subtarget property. Usually runtime enforced max is
// 256.
MDBuilder MDB(Mod->getContext());
MaxWorkGroupSizeRange = MDB.createRange(APInt(32, 0), APInt(32, 2048));
const Triple &TT = TM->getTargetTriple();
IsAMDGCN = TT.getArch() == Triple::amdgcn;
IsAMDHSA = TT.getOS() == Triple::AMDHSA;
return false;
}
bool AMDGPUPromoteAlloca::runOnFunction(Function &F) {
if (!TM || skipFunction(F))
return false;
const AMDGPUSubtarget &ST = TM->getSubtarget<AMDGPUSubtarget>(F);
if (!ST.isPromoteAllocaEnabled())
return false;
AS = AMDGPU::getAMDGPUAS(*F.getParent());
FunctionType *FTy = F.getFunctionType();
// 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() == AS.LOCAL_ADDRESS) {
LocalMemLimit = 0;
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() != AS.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;
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"
);
BasicBlock &EntryBB = *F.begin();
for (auto I = EntryBB.begin(), E = EntryBB.end(); I != E; ) {
AllocaInst *AI = dyn_cast<AllocaInst>(I);
++I;
if (AI)
handleAlloca(*AI);
}
return true;
}
std::pair<Value *, Value *>
AMDGPUPromoteAlloca::getLocalSizeYZ(IRBuilder<> &Builder) {
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, {});
LocalSizeY->setMetadata(LLVMContext::MD_range, MaxWorkGroupSizeRange);
LocalSizeZ->setMetadata(LLVMContext::MD_range, MaxWorkGroupSizeRange);
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, AS.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(CastDispatchPtr, 1);
LoadInst *LoadXY = Builder.CreateAlignedLoad(GEPXY, 4);
Value *GEPZU = Builder.CreateConstInBoundsGEP1_64(CastDispatchPtr, 2);
LoadInst *LoadZU = Builder.CreateAlignedLoad(GEPZU, 4);
MDNode *MD = MDNode::get(Mod->getContext(), None);
LoadXY->setMetadata(LLVMContext::MD_invariant_load, MD);
LoadZU->setMetadata(LLVMContext::MD_invariant_load, MD);
LoadZU->setMetadata(LLVMContext::MD_range, MaxWorkGroupSizeRange);
// 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) {
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);
CI->setMetadata(LLVMContext::MD_range, MaxWorkGroupSizeRange);
return CI;
}
static VectorType *arrayTypeToVecType(Type *ArrayTy) {
return VectorType::get(ArrayTy->getArrayElementType(),
ArrayTy->getArrayNumElements());
}
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:
case Instruction::BitCast:
case Instruction::AddrSpaceCast:
return true;
case Instruction::Store: {
// Must be the stored pointer operand, not a stored value.
StoreInst *SI = cast<StoreInst>(Inst);
return SI->getPointerOperand() == User;
}
default:
return false;
}
}
static bool tryPromoteAllocaToVector(AllocaInst *Alloca, AMDGPUAS AS) {
ArrayType *AllocaTy = dyn_cast<ArrayType>(Alloca->getAllocatedType());
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.
if (!AllocaTy ||
AllocaTy->getElementType()->isVectorTy() ||
AllocaTy->getNumElements() > 4 ||
AllocaTy->getNumElements() < 2) {
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) {
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 = arrayTypeToVecType(AllocaTy);
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: {
Type *VecPtrTy = VectorTy->getPointerTo(AS.PRIVATE_ADDRESS);
Value *Ptr = Inst->getOperand(0);
Value *Index = calculateVectorIndex(Ptr, GEPVectorIdx);
Value *BitCast = Builder.CreateBitCast(Alloca, VecPtrTy);
Value *VecValue = Builder.CreateLoad(BitCast);
Value *ExtractElement = Builder.CreateExtractElement(VecValue, Index);
Inst->replaceAllUsesWith(ExtractElement);
Inst->eraseFromParent();
break;
}
case Instruction::Store: {
Type *VecPtrTy = VectorTy->getPointerTo(AS.PRIVATE_ADDRESS);
Value *Ptr = Inst->getOperand(1);
Value *Index = calculateVectorIndex(Ptr, GEPVectorIdx);
Value *BitCast = Builder.CreateBitCast(Alloca, VecPtrTy);
Value *VecValue = Builder.CreateLoad(BitCast);
Value *NewVecValue = Builder.CreateInsertElement(VecValue,
Inst->getOperand(0),
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::invariant_group_barrier:
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) {
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;
}
// FIXME: Should try to pick the most likely to be profitable allocas first.
void AMDGPUPromoteAlloca::handleAlloca(AllocaInst &I) {
// Array allocations are probably not worth handling, since an allocation of
// the array type is the canonical form.
if (!I.isStaticAlloca() || I.isArrayAllocation())
return;
IRBuilder<> Builder(&I);
// First try to replace the alloca with a vector
Type *AllocaTy = I.getAllocatedType();
DEBUG(dbgs() << "Trying to promote " << I << '\n');
if (tryPromoteAllocaToVector(&I, AS)) {
DEBUG(dbgs() << " alloca is not a candidate for vectorization.\n");
return;
}
const Function &ContainingFunction = *I.getParent()->getParent();
// 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.
if (AMDGPU::isShader(ContainingFunction.getCallingConv()))
return;
const AMDGPUSubtarget &ST =
TM->getSubtarget<AMDGPUSubtarget>(ContainingFunction);
// FIXME: We should also try to get this value from the reqd_work_group_size
// function attribute if it is available.
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) {
DEBUG(dbgs() << " " << AllocSize
<< " bytes of local memory not available to promote\n");
return;
}
CurrentLocalMemUsage = NewSize;
std::vector<Value*> WorkList;
if (!collectUsesWithPtrTypes(&I, &I, WorkList)) {
DEBUG(dbgs() << " Do not know how to convert all uses\n");
return;
}
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,
AS.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, AS.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, AS.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->getRawSource(),
MemCpy->getLength(), MemCpy->getAlignment(),
MemCpy->isVolatile());
Intr->eraseFromParent();
continue;
}
case Intrinsic::memmove: {
MemMoveInst *MemMove = cast<MemMoveInst>(Intr);
Builder.CreateMemMove(MemMove->getRawDest(), MemMove->getRawSource(),
MemMove->getLength(), MemMove->getAlignment(),
MemMove->isVolatile());
Intr->eraseFromParent();
continue;
}
case Intrinsic::memset: {
MemSetInst *MemSet = cast<MemSetInst>(Intr);
Builder.CreateMemSet(MemSet->getRawDest(), MemSet->getValue(),
MemSet->getLength(), MemSet->getAlignment(),
MemSet->isVolatile());
Intr->eraseFromParent();
continue;
}
case Intrinsic::invariant_start:
case Intrinsic::invariant_end:
case Intrinsic::invariant_group_barrier:
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, AS.LOCAL_ADDRESS) }
);
CallInst *NewCall = Builder.CreateCall(
ObjectSize, {Src, Intr->getOperand(1), Intr->getOperand(2)});
Intr->replaceAllUsesWith(NewCall);
Intr->eraseFromParent();
continue;
}
default:
Intr->print(errs());
llvm_unreachable("Don't know how to promote alloca intrinsic use.");
}
}
}
FunctionPass *llvm::createAMDGPUPromoteAlloca(const TargetMachine *TM) {
return new AMDGPUPromoteAlloca(TM);
}
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