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/*========================== begin_copyright_notice ============================
Copyright (C) 2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#include "ModuleAllocaAnalysis.hpp"
#include "Compiler/Optimizer/OpenCLPasses/KernelArgs.hpp"
#include "Compiler/MetaDataUtilsWrapper.h"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/CISACodeGen/GenCodeGenModule.h"
#include "llvm/IR/Instructions.h"
using namespace llvm;
namespace IGC
{
ModuleAllocaAnalysis::ModuleAllocaAnalysis() : ModulePass(ID)
{
initializeModuleAllocaAnalysisPass(*PassRegistry::getPassRegistry());
}
ModuleAllocaAnalysis::~ModuleAllocaAnalysis()
{
for (auto I = InfoMap.begin(), E = InfoMap.end(); I != E; ++I)
delete I->second;
}
void ModuleAllocaAnalysis::getAnalysisUsage(AnalysisUsage& AU) const
{
AU.setPreservesAll();
AU.addRequired<MetaDataUtilsWrapper>();
AU.addRequired<CodeGenContextWrapper>();
}
StringRef ModuleAllocaAnalysis::getPassName() const
{
return "ModuleAllocaAnalysis";
}
bool ModuleAllocaAnalysis::runOnModule(Module& mod)
{
M = &mod;
FGA = getAnalysisIfAvailable<GenXFunctionGroupAnalysis>();
analyze();
return false;
}
bool ModuleAllocaAnalysis::safeToUseScratchSpace() const
{
IGC_ASSERT(M);
IGCMD::MetaDataUtils* pMdUtils = getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();
ModuleMetaData& modMD = *getAnalysis<MetaDataUtilsWrapper>().getModuleMetaData();
CodeGenContext& Ctx = *getAnalysis<CodeGenContextWrapper>().getCodeGenContext();
//
// Update UseScratchSpacePrivateMemory based on WA and be consistent with
// the implementation of CEncoder::ByteScatter().
//
if (Ctx.m_DriverInfo.NeedWAToTransformA32MessagesToA64()
&& Ctx.platform.getWATable().WaNoA32ByteScatteredStatelessMessages)
{
return false;
}
//
// For now, all APIs that use scratch space for private memory, must use scratch
// memory except OpenCL, which can also use non-scratch space. For debugging
// purpose, a registry key is used for OCL to turn ocl-use-scratch on/off.
//
bool supportsScratchSpacePrivateMemory = Ctx.m_DriverInfo.supportsScratchSpacePrivateMemory();
bool supportsStatelessSpacePrivateMemory = Ctx.m_DriverInfo.supportsStatelessSpacePrivateMemory();
bool bOCLLegacyStatelessCheck = true;
if (supportsScratchSpacePrivateMemory) {
if (Ctx.type == ShaderType::OPENCL_SHADER) {
if (Ctx.platform.hasScratchSurface() && !Ctx.m_DriverInfo.UseScratchSpaceForATSPlus()) {
supportsScratchSpacePrivateMemory = Ctx.platform.useScratchSpaceForOCL();
//IGC has some legacy cases where stateless private memory must be used. This flag is to remove them. If regression happens, revert it.
bOCLLegacyStatelessCheck = !(Ctx.platform.hasScratchSurface() && IGC_IS_FLAG_ENABLED(RemoveLegacyOCLStatelessPrivateMemoryCases));
}
}
}
if (Ctx.allocatePrivateAsGlobalBuffer())
{
return false;
}
if ((modMD.compOpt.OptDisable && bOCLLegacyStatelessCheck) || !supportsScratchSpacePrivateMemory)
{
return false;
}
//
// Do not use scratch space if module has any stack call.
// Do not use scratch space if modeule has any variable length alloca
//
if (bOCLLegacyStatelessCheck) {
if (auto * FGA = getAnalysisIfAvailable<GenXFunctionGroupAnalysis>()) {
if (FGA->getModule() == M) {
if (FGA->getIndirectCallGroup() != nullptr)
return false;
for (auto& I : *FGA) {
if (I->hasStackCall())
return false;
if (I->hasVariableLengthAlloca())
return false;
}
}
}
else {
// Check individual functions if FGA not available
for (auto& F : *M) {
if (F.hasFnAttribute("visaStackCall") || F.hasFnAttribute("hasVLA"))
return false;
}
}
}
const llvm::DataLayout* DL = &M->getDataLayout();
for (auto& F : *M) {
if (F.isDeclaration())
continue;
// Check each instr of this function.
for (auto& BB : F) {
for (auto& I : BB) {
if (AddrSpaceCastInst * CI = dyn_cast<AddrSpaceCastInst>(&I)) {
// It is not safe to use scratch space as private memory if kernel does
// AS casting to ADDRESS_SPACE_GLOBAL_OR_PRIVATE or ADDRESS_SPACE_PRIVATE.
// See speical hack CI code generated at ProgramScopeConstantResolution
const ADDRESS_SPACE targetAS = (ADDRESS_SPACE)(cast<PointerType>(CI->getType()))->getAddressSpace();
if (targetAS == ADDRESS_SPACE_GLOBAL_OR_PRIVATE || targetAS == ADDRESS_SPACE_PRIVATE) {
return false;
}
}
if (Ctx.type == ShaderType::OPENCL_SHADER) {
// PtrToInt may be used to test if pointer is null, then we cannot
// distinguish nullptr versus zero offset. This causes a problem
// with an OpenCL3.0 test. see cassian/oclc_address_space_qualifiers
if (PtrToIntInst* IPI = dyn_cast<PtrToIntInst>(&I)) {
if (IPI->getPointerAddressSpace() == ADDRESS_SPACE_PRIVATE) {
return false;
}
}
}
}
}
if (!isEntryFunc(pMdUtils, &F))
continue;
//
// OCL kernel arguments with type like queue_t and struct are expressed as
// pointer type. Since there is no explicit AS associated with those pointers,
// e.g., %opencl.queue_t*, to have both host and device use the same pointer
// size for those arguments, it is better to disable the use of scratch memory.
//
// TODO: fixed those types (they should be in global address space)
if (Ctx.type == ShaderType::OPENCL_SHADER && IGC_IS_FLAG_ENABLED(ForceStatelessForQueueT)) {
if (!F.arg_empty()) {
KernelArgs kernelArgs(F, DL, pMdUtils, &modMD, Ctx.platform.getGRFSize());
for (auto arg : kernelArgs) {
const KernelArg::ArgType argTy = arg.getArgType();
if (argTy == KernelArg::ArgType::PTR_DEVICE_QUEUE)
{
return false;
}
}
}
}
//
// Each thread has up to 2 MB scratch space to use. That is, each WI
// has up to (2*1024*1024 / 8) bytes of scratch space in SIMD8 mode.
//
auto funcInfoMD = pMdUtils->getFunctionsInfoItem(&F);
bool isGeometryStageShader = Ctx.type == ShaderType::VERTEX_SHADER ||
Ctx.type == ShaderType::HULL_SHADER ||
Ctx.type == ShaderType::DOMAIN_SHADER ||
Ctx.type == ShaderType::GEOMETRY_SHADER;
//FIXME: Below heuristics is not a clean design. Revisit this!
//Start with simd16 or simd32 correspondingly if MinDispatchMode() is 8 or 16, which allows the medium size of space per WI
// (simd8: largest, simd32, smallest). In doing so, there will be
// some space left for spilling in simd8 if spilling happens.
int32_t simd_size = isGeometryStageShader ? numLanes(Ctx.platform.getMinDispatchMode()) :
(Ctx.platform.getMinDispatchMode() == SIMDMode::SIMD8 ? numLanes(SIMDMode::SIMD16) : numLanes(SIMDMode::SIMD32));
const int32_t subGrpSize = funcInfoMD->getSubGroupSize()->getSIMD_size();
if (subGrpSize > simd_size)
simd_size = std::min(subGrpSize, static_cast<int32_t>(numLanes(SIMDMode::SIMD32)));
int32_t groupSize = IGCMD::IGCMetaDataHelper::getThreadGroupSize(*pMdUtils, &F);
if (groupSize == 0)
groupSize = IGCMD::IGCMetaDataHelper::getThreadGroupSizeHint(*pMdUtils, &F);
if (groupSize > simd_size)
simd_size = std::min(groupSize, static_cast<int32_t>(numLanes(SIMDMode::SIMD32)));
// if one API doesn't support stateless, we should try to use smallest dispatch mode
// which can hold more pvt_data to avoid error out.
if (Ctx.platform.hasScratchSurface() && Ctx.m_DriverInfo.supportsSeparatingSpillAndPrivateScratchMemorySpace() && !supportsStatelessSpacePrivateMemory)
simd_size = numLanes(Ctx.platform.getMinDispatchMode());
unsigned maxScratchSpaceBytes = Ctx.platform.maxPerThreadScratchSpace();
unsigned scratchSpaceLimitPerWI = maxScratchSpaceBytes / simd_size;
//
// If spill happens, since the offset of scratch block rw send message
// has only 12b, an assertion will be triggered if used scratch space
// size >= 128 KB, here 128 KB = 2^12 * 256b.
//
const unsigned int totalPrivateMemPerWI = getTotalPrivateMemPerWI(&F);
//FIXME: for now, to shrink size, let's use SIMD8 if have to.
//later, maybe, we want to change to legacy behavior: SIMD16, to avoid potential spill.
//but even so, when we support slot0 and slot1, then, we could still use SIMD8.
if (Ctx.platform.hasScratchSurface() &&
Ctx.hasSyncRTCalls() &&
totalPrivateMemPerWI > scratchSpaceLimitPerWI) {
simd_size = numLanes(Ctx.platform.getMinDispatchMode());
scratchSpaceLimitPerWI = maxScratchSpaceBytes / simd_size;
}
if (totalPrivateMemPerWI > scratchSpaceLimitPerWI) {
// IGC errors out when we are trying to remove statelesspvtmem of OCL (even though OCl still supports statelesspvtmem).
// This assertion tests a scenario where (pvt_mem_usage > 256k) while statelessprivatememory is not supported.
IGC_ASSERT_EXIT(bOCLLegacyStatelessCheck);
if (!supportsStatelessSpacePrivateMemory)
{
// For XeHP_SDV and above, if any API doesn't support statelesspvtmem, error it out if we find a case where (pvt_mem > 256k).
// This assertion found a scenario where (pvt_mem_usage > 256k) while statelessprivatememory is not supported.
IGC_ASSERT(0);
return true;
}
return false;
}
}
// It is safe to use scratch space for private memory.
return true;
}
unsigned ModuleAllocaAnalysis::getConstBufferOffset(AllocaInst* AI) const {
IGC_ASSERT(isa<ConstantInt>(AI->getArraySize()));
Function* F = AI->getParent()->getParent();
return getFuncAllocaInfo(F)->AllocaDesc[AI].first;
}
unsigned ModuleAllocaAnalysis::getConstBufferSize(AllocaInst* AI) const {
IGC_ASSERT(isa<ConstantInt>(AI->getArraySize()));
Function* F = AI->getParent()->getParent();
return getFuncAllocaInfo(F)->AllocaDesc[AI].second;
}
SmallVector<AllocaInst*, 8>& ModuleAllocaAnalysis::getAllocaInsts(Function* F) const {
return getFuncAllocaInfo(F)->Allocas;
}
unsigned ModuleAllocaAnalysis::getTotalPrivateMemPerWI(Function* F) const {
auto FI = getFuncAllocaInfo(F);
return FI ? FI->TotalSize : 0;
}
ModuleAllocaAnalysis::FunctionAllocaInfo* ModuleAllocaAnalysis::getFuncAllocaInfo(Function* F) const {
auto Iter = InfoMap.find(F);
if (Iter != InfoMap.end())
return Iter->second;
return nullptr;
}
ModuleAllocaAnalysis::FunctionAllocaInfo* ModuleAllocaAnalysis::getOrCreateFuncAllocaInfo(Function* F) {
auto Iter = InfoMap.find(F);
if (Iter != InfoMap.end())
return Iter->second;
auto AllocaInfo = new FunctionAllocaInfo;
InfoMap[F] = AllocaInfo;
return AllocaInfo;
}
void ModuleAllocaAnalysis::analyze() {
if (FGA && FGA->getModule()) {
IGC_ASSERT(FGA->getModule() == M);
for (auto FG : *FGA)
analyze(FG);
}
else {
for (auto& F : M->getFunctionList()) {
if (F.empty())
continue;
unsigned Offset = 0;
alignment_t Alignment = 0;
analyze(&F, Offset, Alignment);
if (Alignment > 0)
Offset = iSTD::Align(Offset, (size_t)Alignment);
getOrCreateFuncAllocaInfo(&F)->TotalSize = Offset;
}
}
}
void ModuleAllocaAnalysis::analyze(IGC::FunctionGroup* FG)
{
// Calculate the size of private-memory we need to allocate to
// every function-sub-group. Eache sub-group is led by a kernel or
// a stack-call function.
// Note that the function order does affect the final total amount of
// private memory due to possible alignment constraints.
//
for (auto SubG : FG->Functions) {
unsigned Offset = 0;
alignment_t Alignment = 0;
for (Function* F : *SubG) {
if (F->empty())
continue;
analyze(F, Offset, Alignment);
}
// Use the final offset as the total size.
if (Alignment > 0)
Offset = iSTD::Align(Offset, (size_t)Alignment);
// All functions in this group will get the same final size.
for (Function* F : *SubG) {
if (F->empty())
continue;
getOrCreateFuncAllocaInfo(F)->TotalSize = Offset;
}
}
}
void ModuleAllocaAnalysis::analyze(Function* F, unsigned& Offset, alignment_t& MaxAlignment)
{
const DataLayout* DL = &M->getDataLayout();
// Create alloca info even when there is no alloca, so that each function gets
// an info entry.
FunctionAllocaInfo* AllocaInfo = getOrCreateFuncAllocaInfo(F);
// Collect allocas.
SmallVector<AllocaInst*, 8> Allocas;
for (auto& BB : F->getBasicBlockList()) {
for (auto& Inst : BB.getInstList()) {
if (AllocaInst* AI = dyn_cast<AllocaInst>(&Inst)) {
Allocas.push_back(AI);
}
}
}
if (Allocas.empty())
return;
// Group by alignment and smallest first.
auto getAlignment = [=](AllocaInst* AI) -> alignment_t {
alignment_t Alignment = AI->getAlignment();
if (Alignment == 0)
Alignment = DL->getABITypeAlignment(AI->getAllocatedType());
return Alignment;
};
std::sort(Allocas.begin(), Allocas.end(),
[=](AllocaInst* AI1, AllocaInst* AI2) {
return getAlignment(AI1) < getAlignment(AI2);
});
for (auto AI : Allocas) {
// Align alloca offset.
auto Alignment = getAlignment(AI);
Offset = iSTD::Align(Offset, (size_t)Alignment);
// Keep track of the maximal alignment seen so far.
if (Alignment > MaxAlignment)
MaxAlignment = Alignment;
// Compute alloca size. We don't know the variable length
// alloca size so skip it.
if (!isa<ConstantInt>(AI->getArraySize())) {
continue;
}
ConstantInt* const SizeVal = cast<ConstantInt>(AI->getArraySize());
IGC_ASSERT(nullptr != SizeVal);
unsigned CurSize = (unsigned)(SizeVal->getZExtValue() *
DL->getTypeAllocSize(AI->getAllocatedType()));
AllocaInfo->setAllocaDesc(AI, Offset, CurSize);
// Increment the current offset for the next alloca.
Offset += CurSize;
}
// Update collected allocas into the function alloca info object.
AllocaInfo->Allocas.swap(Allocas);
}
char ModuleAllocaAnalysis::ID = 0;
// Register pass to igc-opt
#define PASS_FLAG "igc-module-alloca-info"
#define PASS_DESCRIPTION "Analyse memory usage based on alloca instructions"
#define PASS_CFG_ONLY true
#define PASS_ANALYSIS true
IGC_INITIALIZE_PASS_BEGIN(ModuleAllocaAnalysis, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(MetaDataUtilsWrapper)
IGC_INITIALIZE_PASS_END(ModuleAllocaAnalysis, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
} // namespace IGC
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