/*===================== begin_copyright_notice ==================================

Copyright (c) 2017 Intel Corporation

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copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
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The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

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OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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======================= end_copyright_notice ==================================*/

#include "AdaptorCommon/ImplicitArgs.hpp"
#include "Compiler/Optimizer/OpenCLPasses/LocalBuffers/InlineLocalsResolution.hpp"
#include "Compiler/CodeGenPublic.h"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/CISACodeGen/helper.h"
#include "Compiler/DebugInfo/DebugInfoUtils.hpp"

#include "common/LLVMWarningsPush.hpp"
#include <llvm/IR/Module.h>
#include <llvm/IR/Instructions.h>
#include "common/LLVMWarningsPop.hpp"

using namespace llvm;
using namespace IGC;
using namespace IGC::IGCMD;


// Register pass to igc-opt
#define PASS_FLAG "igc-resolve-inline-locals"
#define PASS_DESCRIPTION "Resolve inline local variables/buffers"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(InlineLocalsResolution, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(MetaDataUtilsWrapper)
IGC_INITIALIZE_PASS_END(InlineLocalsResolution, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)

char InlineLocalsResolution::ID = 0;
const llvm::StringRef BUILTIN_MEMPOOL = "__builtin_IB_AllocLocalMemPool";

InlineLocalsResolution::InlineLocalsResolution() : 
    ModulePass(ID), m_pGV(nullptr)
{
    initializeInlineLocalsResolutionPass(*PassRegistry::getPassRegistry());
}

const unsigned int InlineLocalsResolution::VALID_LOCAL_HIGH_BITS = 0x10000000;

static bool useAsPointerOnly(Value *V) {
    assert(V->getType()->isPointerTy() && "Expect the input value is a pointer!");

    SmallSet<PHINode *, 8> VisitedPHIs;
    SmallVector<Value *, 16> WorkList;
    WorkList.push_back(V);

    StoreInst *ST = nullptr;
    PHINode *PN = nullptr;
    while (!WorkList.empty()) {
        Value *Val = WorkList.pop_back_val();
        for (auto *U : Val->users()) {
            Operator *Op = dyn_cast<Operator>(U);
            if (!Op)
                continue;
            switch (Op->getOpcode()) {
            default:
                // Bail out for unknown operations.
                return false;
            case Instruction::Store:
                ST = cast<StoreInst>(U);
                // Bail out if it's used as the value operand.
                if (ST->getValueOperand() == Val)
                    return false;
                // FALL THROUGH
            case Instruction::Load:
                // Safe use in LD/ST as pointer only.
                continue;
            case Instruction::PHI:
                PN = cast<PHINode>(U);
                // Skip if it's already visited.
                if (VisitedPHIs.count(PN))
                    continue;
                VisitedPHIs.insert(PN);
                // FALL THROUGH
            case Instruction::BitCast:
            case Instruction::Select:
            case Instruction::GetElementPtr:
                // Need to check their usage further.
                break;
            }
            WorkList.push_back(U);
        }
    }

    return true;
}

bool InlineLocalsResolution::runOnModule(Module &M)
{
    MetaDataUtils *pMdUtils = getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();

    // Compute the offset of each inline local in the kernel,
    // and their total size.
    std::map<Function*, unsigned int> sizeMap;
    collectInfoOnSharedLocalMem(M);
    computeOffsetList(M, sizeMap);

    LLVMContext& C = M.getContext();

    for( Module::iterator I = M.begin(), E = M.end(); I != E; ++I )
    {
        Function* pFunc = &(*I);

        if (pFunc->isDeclaration() || !isEntryFunc(pMdUtils, pFunc))
        {
            continue;
        }

        unsigned int totalSize = 0;

        // Get the offset at which local arguments start
        auto sizeIter = sizeMap.find(pFunc);
        if( sizeIter != sizeMap.end() )
        {
            totalSize += sizeIter->second;
        }

        // Set the high 16 bits to a non-0 value.
        totalSize = (totalSize & 0xFFFF);

        bool IsFirstSLMArgument = true;
        for( Function::arg_iterator A = pFunc->arg_begin(), AE = pFunc->arg_end(); A != AE; ++A )
        {
            Argument* arg = &(*A);
            PointerType* ptrType = dyn_cast<PointerType>(arg->getType());
            // Check that this is a pointer
            if( !ptrType )
            {
                continue;
            }

            // To the local address space
            if( ptrType->getAddressSpace() != ADDRESS_SPACE_LOCAL )
            {
                continue;
            }

            // Which is used
            if( arg->use_empty() )
            {
                continue;
            }

            bool UseAsPointerOnly = useAsPointerOnly(arg);
            unsigned Offset = totalSize;
            if (!UseAsPointerOnly)
                Offset |= VALID_LOCAL_HIGH_BITS;

            if (IsFirstSLMArgument) {
                auto BufType = ArrayType::get(Type::getInt8Ty(M.getContext()), 0);
                auto ExtSLM = new GlobalVariable(M, BufType, false, GlobalVariable::ExternalLinkage, nullptr,
					pFunc->getName() + "-ExtSLM", nullptr, GlobalVariable::ThreadLocalMode::NotThreadLocal,
					ADDRESS_SPACE_LOCAL);
                auto NewPtr = ConstantExpr::getBitCast(ExtSLM, arg->getType());
                arg->replaceAllUsesWith(NewPtr);
                // Update MD.
                LocalOffsetMetaDataHandle lo = LocalOffsetMetaDataHandle(LocalOffsetMetaData::get());
                lo->setVar(ExtSLM);
                lo->setOffset(Offset);
                pMdUtils->getFunctionsInfoItem(pFunc)->addLocalOffsetsItem(lo);
                IsFirstSLMArgument = false;
            } else {
                // FIXME: The following code should be removed as well by
                // populating similar adjustment in prolog during code
                // emission.
                // Ok, now we need to add an offset, in bytes, which is equal to totalSize.
                // Bitcast to i8*, GEP, bitcast back to original type.
                Value* sizeConstant = ConstantInt::get(Type::getInt32Ty(C), Offset);
                SmallVector<Value*, 1> idx(1, sizeConstant);
                Instruction* pInsertBefore = &(*pFunc->begin()->getFirstInsertionPt());
                Type* pLocalCharPtrType = Type::getInt8Ty(C)->getPointerTo(ADDRESS_SPACE_LOCAL);
                Instruction* pCharPtr = BitCastInst::CreatePointerCast(arg, pLocalCharPtrType, "localToChar", pInsertBefore);
                Value* pMovedCharPtr = GetElementPtrInst::Create(nullptr, pCharPtr, idx, "movedLocal", pInsertBefore);

                Value* pMovedPtr = CastInst::CreatePointerCast(pMovedCharPtr, ptrType, "charToLocal", pInsertBefore);
                
                // Running over arg users and use replaceUsesOfWith to fix them is not enough,
                // because it does not cover the usage of arg in metadata (e.g. for debug info intrinsic).
                // Thus, replaceAllUsesWith should be used in order to fix also debug info.
                arg->replaceAllUsesWith(pMovedPtr);
                // The above operation changed also the "arg" operand in "charPtr" to "movedPtr"
                // Thus, we need to fix it back (otherwise the LLVM IR will be invalid)
                pCharPtr->replaceUsesOfWith(pMovedPtr, arg);
            }
        }
    }

    return true;
}

void InlineLocalsResolution::collectInfoOnSharedLocalMem(Module& M)
{

    // first we collect SLM usage on GET_MEMPOOL_PTR
    if (M.getFunction(BUILTIN_MEMPOOL) != nullptr)
    {
        SmallVector<CallInst*, 8> callsToReplace;
        unsigned maxBytesOnModule = 0;
        unsigned maxAlignOnModule = 0;

        // scan inst to collect all call instructions

        for (Module::iterator F = M.begin(), FE = M.end(); F != FE; ++F)
        {
            if (F->isDeclaration())
            {
                continue;
            }

            unsigned maxBytesOnFunc = 0;
            for (auto I = inst_begin(&(*F)), IE = inst_end(&(*F)); I != IE; ++I)
            {
                Instruction* inst = &(*I);
                if (CallInst *CI = dyn_cast<CallInst>(inst))
                {
                    Function *pFunc = CI->getCalledFunction();
                    if (pFunc && pFunc->getName().equals(BUILTIN_MEMPOOL))
                    {
                        // should always be called with constant operands
                        assert(isa<ConstantInt>(CI->getArgOperand(0)));
                        assert(isa<ConstantInt>(CI->getArgOperand(1)));

                        unsigned int size = unsigned(cast<ConstantInt>(CI->getArgOperand(0))->getZExtValue());
                        unsigned int align = unsigned(cast<ConstantInt>(CI->getArgOperand(1))->getZExtValue());

                        maxBytesOnFunc = std::max(maxBytesOnFunc, size);
                        maxBytesOnModule = std::max(maxBytesOnModule, size);
                        maxAlignOnModule = std::max(maxAlignOnModule, align);

                        callsToReplace.push_back(CI);
                    }
                }
            }
            if (maxBytesOnFunc != 0)
            {
                m_FuncToMemPoolSizeMap[&(*F)] = maxBytesOnFunc;
            }
        }

        if (!callsToReplace.empty())
        {

            Type *bufType = ArrayType::get(Type::getInt8Ty(M.getContext()), uint64_t(maxBytesOnModule));
            Twine globalName = Twine("GenSLM") + Twine(".LocalMemPoolOnGetMemPoolPtr");

            m_pGV = new GlobalVariable(M, bufType, false,
                GlobalVariable::ExternalLinkage, ConstantAggregateZero::get(bufType),
                globalName, nullptr,
                GlobalVariable::ThreadLocalMode::NotThreadLocal,
                ADDRESS_SPACE_LOCAL);

            m_pGV->setAlignment(maxAlignOnModule);

            for (auto call : callsToReplace)
            {
                CastInst *cast =
                    new BitCastInst(
                    m_pGV,
                    call->getCalledFunction()->getReturnType(),
                    "mempoolcast",
                    call);

                cast->setDebugLoc(call->getDebugLoc());

                call->replaceAllUsesWith(cast);
                call->eraseFromParent();
            }
        }
    }

    // let's loop all global variables
    for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I)
    {
        // We only care about global variables, not other globals.
        GlobalVariable* globalVar = dyn_cast<GlobalVariable>(&*I);
        if (!globalVar)
        {
            continue;
        }

        PointerType* ptrType = dyn_cast<PointerType>(globalVar->getType());
        assert(ptrType && "The type of a global variable must be a pointer type");
        if (!ptrType)
        {
            continue;
        }

        // We only care about local address space here.
        if (ptrType->getAddressSpace() != ADDRESS_SPACE_LOCAL)
        {
            continue;
        }

		// For each SLM buffer, make it external to avoid alignment
		// changing by llvm.
		globalVar->setLinkage(GlobalValue::ExternalLinkage);

        // Find the functions which this globalVar belongs to.... 
        for (Value::user_iterator U = globalVar->user_begin(), UE = globalVar->user_end(); U != UE; ++U)
        {
            Instruction* user = dyn_cast<Instruction>(*U);
            if (!user)
            {
                continue;
            }

            m_FuncToVarsMap[user->getParent()->getParent()].insert(globalVar);
        }
    }

    // set debugging info, and insert mov inst.
    IF_DEBUG_INFO(for (auto I : m_FuncToVarsMap))
    {
        IF_DEBUG_INFO(Function *userFunc = I.first;)
        IF_DEBUG_INFO(for (auto G : I.second))
        {
            IF_DEBUG_INFO(Instruction* pInsertBefore = &(*userFunc->begin()->getFirstInsertionPt());)
            TODO("Should inline local buffer points to origin offset 'globalVar' or to fixed offset 'pMovedPtr'?");
            IF_DEBUG_INFO(DebugInfoUtils::UpdateGlobalVarDebugInfo(G, G, pInsertBefore, true););
        }
    }
}

void InlineLocalsResolution::computeOffsetList(Module& M, std::map<Function*, unsigned int>& sizeMap)
{
    std::map<Function*, std::map<GlobalVariable*, unsigned int>> offsetMap;
    MetaDataUtils *pMdUtils = getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();
    DataLayout DL = M.getDataLayout();
    CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();

    if (m_FuncToVarsMap.empty())
    {
        return;
    }

    // let's travese the CallGraph to calculate the local 
    // variables of kernel from all user functions.
    m_chkSet.clear();
    for (auto &N : CG)
    {
        Function *f = N.second->getFunction();
        if (!f || f->isDeclaration() || m_chkSet.find(f) != m_chkSet.end()) continue;
        traveseCGN(*N.second);
    }

    // set up the offsetMap;
    for (auto I : m_FuncToVarsMap)
    {
        Function* F = I.first;

        // loop all global variables
        for (auto G : I.second)
        {
            // std::map initializes with zero if the value is not present.
            unsigned int offset = sizeMap[F];
            offset = iSTD::Align(offset, DL.getPreferredAlignment(G));

            // Save the offset of the current local
            // (set the high bits to be non-0 here too)
            offsetMap[F][G] = (offset & 0xFFFF);

            // And the total size after this local is added
            PointerType* ptrType = dyn_cast<PointerType>(G->getType());
            Type* varType = ptrType->getElementType();
            if (G == m_pGV)
            {
                // it is GetMemPoolPtr usage
                offset += m_FuncToMemPoolSizeMap[F];
            }
            else
            {
                offset += (unsigned int)DL.getTypeAllocSize(varType);
            }
            sizeMap[F] = offset;
        }
    }

    // Ok, we've collected the information, now write it into the MD.
    for (auto iter = sizeMap.begin(), end = sizeMap.end(); iter != end; ++iter)
    {
        // ignore non-entry functions. 
        if (!isEntryFunc(pMdUtils, iter->first))
        {
            continue;
        }

        // If this function doesn't have any locals, no need for MD.
        if (iter->second == 0)
        {
            continue;
        }

        // We need the total size to have at least 32-byte alignment.
        // This is because right after the space allocated to the inline locals,
        // we are going to have inline parameters. So, we need to make sure the
        // first local parameter is appropriately aligned, which, at worst,
        // can be 256 bits.
        iter->second = iSTD::Align(iter->second, 32);

        // Add the size information of this function
        pMdUtils->getFunctionsInfoItem(iter->first)->setLocalSize(iter->second);

        // And now the offsets.
        for (auto offsetIter = offsetMap[iter->first].begin(), offsetEnd = offsetMap[iter->first].end(); offsetIter != offsetEnd; ++offsetIter)
        {
            LocalOffsetMetaDataHandle lo = LocalOffsetMetaDataHandle(LocalOffsetMetaData::get());
            unsigned Offset = offsetIter->second;
            if (!useAsPointerOnly(offsetIter->first))
                Offset |= VALID_LOCAL_HIGH_BITS;
            lo->setVar(offsetIter->first);
            lo->setOffset(Offset);
            pMdUtils->getFunctionsInfoItem(iter->first)->addLocalOffsetsItem(lo);
        }
    }
    pMdUtils->save(M.getContext());
}

void InlineLocalsResolution::traveseCGN(llvm::CallGraphNode &CGN)
{
    Function * f = CGN.getFunction();

    for (auto N : CGN)
    {
        Function *sub = N.second->getFunction();
        if (!sub || sub->isDeclaration()) continue;

        // we reach here, because there is sub-function inside the node
        if (m_chkSet.find(sub) == m_chkSet.end())
        {
            // this sub-routine is not visited before.
            // visit it first
            traveseCGN(*N.second);
        }

        // the sub-routine was visited before, collect information

        // count each global on this sub-routine
        GlobalVariableSet &GS_f = m_FuncToVarsMap[f];
        GlobalVariableSet &GS_sub = m_FuncToVarsMap[sub];
        for (auto I = GS_sub.begin(); I != GS_sub.end(); ++I)
        {
            GS_f.insert(*I);
        }

        // automatic storages
        if (m_FuncToMemPoolSizeMap.find(sub) != m_FuncToMemPoolSizeMap.end())
        {
            // this sub-function has automatic storage
            if (m_FuncToMemPoolSizeMap.find(f) != m_FuncToMemPoolSizeMap.end())
            {
                // caller has its own memory pool size, choose the max  
                m_FuncToMemPoolSizeMap[f] = std::max(m_FuncToMemPoolSizeMap[f], m_FuncToMemPoolSizeMap[sub]);
            }
            else
            {
                m_FuncToMemPoolSizeMap[f] = m_FuncToMemPoolSizeMap[sub];
            }
        }
    }

    // mark this function

    m_chkSet.insert(f);
}
