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

Copyright (c) 2017 Intel Corporation

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


======================= end_copyright_notice ==================================*/

#include "Compiler/LowPrecisionOptPass.hpp"
#include "Compiler/CodeGenContextWrapper.hpp"
#include "Compiler/CodeGenPublic.h"
#include "Compiler/CISACodeGen/helper.h"
#include "Compiler/IGCPassSupport.h"

#include "common/LLVMWarningsPush.hpp"
#include <llvm/Support/CommandLine.h>
#include <llvm/IR/Instructions.h>
#include <llvm/IR/InstIterator.h>
#include "common/LLVMWarningsPop.hpp"

#include "GenISAIntrinsics/GenIntrinsicInst.h"
#include "common/IGCIRBuilder.h"
using namespace llvm;
using namespace IGC;
using namespace IGC::IGCMD;
using namespace GenISAIntrinsic;

char LowPrecisionOpt::ID = 0;

// Register pass to igc-opt
#define PASS_FLAG "igc-low-precision-opt"
#define PASS_DESCRIPTION "Low Precision Opt"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(LowPrecisionOpt, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(MetaDataUtilsWrapper)
IGC_INITIALIZE_PASS_DEPENDENCY(CodeGenContextWrapper)
IGC_INITIALIZE_PASS_END(LowPrecisionOpt, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)

LowPrecisionOpt::LowPrecisionOpt() : FunctionPass(ID)
{
    initializeLowPrecisionOptPass(*PassRegistry::getPassRegistry());
    m_func_llvm_GenISA_DCL_inputVec_f16 = nullptr;
    m_func_llvm_GenISA_DCL_inputVec_f32 = nullptr;
    m_currFunction = nullptr;
    func_llvm_floor_f32 = nullptr;
}

bool LowPrecisionOpt::runOnFunction(Function &F)
{
    m_changed = false;
    CodeGenContextWrapper* pCtxWrapper = &getAnalysis<CodeGenContextWrapper>();
    CodeGenContext* ctx = pCtxWrapper->getCodeGenContext();

    MetaDataUtils *pMdUtils = getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();

    if (pMdUtils->findFunctionsInfoItem(&F) == pMdUtils->end_FunctionsInfo())
    {
        return m_changed;
    }
    llvm::IGCIRBuilder<> builder(F.getContext());
    m_builder = &builder;
    m_currFunction = &F;
    shdrType = ctx->type;
    bundles.clear();
    m_simplifyAlu = true;
    m_changeSample = false;
    visit(F);
    // change sampler only after we simplified fext + ftrunc
    m_simplifyAlu = false;
    m_changeSample = true;
    visit(F);
    std::sort(bundles.begin(), bundles.end(), cmpOperator);
    auto bundleEnd = bundles.end();
    for (auto bundle = bundles.begin(); bundle != bundleEnd; ++bundle)
    {
        (*bundle).cInst->moveBefore(&(*(m_currFunction->getEntryBlock().begin())));
        (*bundle).fpTrunc->moveBefore(&(*(m_currFunction->getEntryBlock().begin())));
    }
    return m_changed;
}

void LowPrecisionOpt::visitFPExtInst(llvm::FPExtInst &I)
{
    if(!m_simplifyAlu)
    {
        return;
    }
    if (I.getOperand(0)->getType()->isHalfTy())
    {
        Instruction* I0 = dyn_cast<Instruction>(I.getOperand(0));
        llvm::GenIntrinsicInst* callInst = llvm::dyn_cast<llvm::GenIntrinsicInst>(I.getOperand(0));

        if (I0 && I0->getOpcode() == Instruction::FPTrunc && I.getDestTy() == I0->getOperand(0)->getType())
        {
            I.replaceAllUsesWith(I0->getOperand(0));
            I.eraseFromParent();
            m_changed = true;
        }
        else if (callInst &&  callInst->hasOneUse())
        {
            GenISAIntrinsic::ID ID = callInst->getIntrinsicID();
            if(ID == GenISAIntrinsic::GenISA_DCL_ShaderInputVec || ID == GenISAIntrinsic::GenISA_DCL_inputVec)
            {
                /*
                Catches a pattern where we have a lowp input, then extend it back up. This
                generates mixed mode instructions and so it's better to keep it as PLN.
                Example if it's used directly in the sample instruction before CNL.
                */

                if (m_func_llvm_GenISA_DCL_inputVec_f32 == nullptr)
                {
                    m_func_llvm_GenISA_DCL_inputVec_f32 = llvm::GenISAIntrinsic::getDeclaration(
                        m_currFunction->getParent(),
                        ID,
                        Type::getFloatTy(m_builder->getContext()));
                }

                m_builder->SetInsertPoint(callInst);
                Value* v = m_builder->CreateCall2(m_func_llvm_GenISA_DCL_inputVec_f32, callInst->getOperand(0), callInst->getOperand(1));
#if VALUE_NAME_ENABLE
                v->setName(callInst->getName());
#endif
                I.replaceAllUsesWith(v);
                I.eraseFromParent();
                callInst->eraseFromParent();
                m_changed = true;
            }
        }
    }
}

void LowPrecisionOpt::visitFPTruncInst(llvm::FPTruncInst &I)
{
    if(!m_simplifyAlu)
    {
        return;
    }
    llvm::GenIntrinsicInst* cInst = llvm::dyn_cast<llvm::GenIntrinsicInst>(I.getOperand(0));

    if (cInst &&
        cInst->getIntrinsicID() == GenISAIntrinsic::GenISA_RuntimeValue)
    {
        if (!IGC_IS_FLAG_ENABLED(HoistPSConstBufferValues) ||
            shdrType != ShaderType::PIXEL_SHADER)
            return;
        moveBundle bundle;
        bundle.index = (uint)llvm::cast<llvm::ConstantInt>(cInst->getOperand(0))->getZExtValue();
        bundle.cInst = cInst;
        bundle.fpTrunc = &I;
        bundles.push_back(bundle);
    }
}

// If all the uses of a sampler instruction are converted to a different floating point type
// try to propagate the type in the sampler
bool LowPrecisionOpt::propagateSamplerType(llvm::GenIntrinsicInst &I)
{
    if (IGC_IS_FLAG_DISABLED(UpConvertF16Sampler) && I.getType()->getVectorElementType()->isHalfTy())
    {
        return false;
    }

    IGC::CodeGenContext &CGContext = *getAnalysis<CodeGenContextWrapper>().getCodeGenContext();
    if (!CGContext.platform.supportFP16())
    {
        return false;
    }
    
    Type* eltTy = I.getType()->getVectorElementType();
    Type *newDstType = nullptr;
    if (eltTy->isFloatingPointTy())
    {
        // check that all uses are extractelement followed by fpext
        newDstType = I.getType()->getVectorElementType()->isFloatTy() ?
            m_builder->getHalfTy() : m_builder->getFloatTy();
        for (auto use = I.user_begin(); use != I.user_end(); ++use)
        {
            auto extractElt = dyn_cast<ExtractElementInst>(*use);
            if (!(extractElt && extractElt->hasOneUse()))
            {
                return false;
            }
            auto fpExtOrTrunc = dyn_cast<CastInst>(*extractElt->user_begin());

            if (!(fpExtOrTrunc && fpExtOrTrunc->getType() == newDstType))
            {
                return false;
            }
        }
    }
    else if (eltTy == m_builder->getInt32Ty())
    {
        // check if we can lower the sampler return to 16-bit
        newDstType = m_builder->getInt16Ty();
        for (auto use = I.user_begin(); use != I.user_end(); ++use)
        {
            auto extractElt = dyn_cast<ExtractElementInst>(*use);
            if (!(extractElt && extractElt->hasOneUse()))
            {
                return false;
            }
            auto isUpperBitClear = [this](User* U)
            {
                // match the pattern 
                // %scalar59 = extractelement <4 x i32> % 83, i32 3
                // % 84 = and i32 %scalar59, 65535
                if (U->getType() != m_builder->getInt32Ty())
                {
                    return false;
                }
                auto andInst = dyn_cast<BinaryOperator>(U);
                if (!andInst || andInst->getOpcode() != BinaryOperator::And)
                {
                    return false;
                }
                auto andSrc1 = dyn_cast<ConstantInt>(andInst->getOperand(1));
                if (!andSrc1 || andSrc1->getZExtValue() != 0xFFFF)
                {
                    return false;
                }
                return true;
            };

            auto Use = *extractElt->user_begin();
            bool isInt32to16Trunc = dyn_cast<TruncInst>(Use) && Use->getType() == m_builder->getInt16Ty();
            if (!isInt32to16Trunc && !isUpperBitClear(Use))
            {
                return false;
            }
        }
    }
    else
    {
        return false;
    }

    VectorType* oldTy = cast<VectorType>(I.getType());
    llvm::SmallVector<llvm::Type*, 4> overloadTys;
    auto retTy = VectorType::get(newDstType, int_cast<unsigned int>(oldTy->getNumElements()));
    overloadTys.push_back(retTy);
    auto ID = I.getIntrinsicID();
    switch (ID)
    {
    case GenISAIntrinsic::GenISA_sampleptr:
    case GenISAIntrinsic::GenISA_sampleBptr:
    case GenISAIntrinsic::GenISA_sampleCptr:
    case GenISAIntrinsic::GenISA_sampleDptr:
    case GenISAIntrinsic::GenISA_sampleDCptr:
    case GenISAIntrinsic::GenISA_sampleLptr:
    case GenISAIntrinsic::GenISA_sampleLCptr:
    case GenISAIntrinsic::GenISA_sampleBCptr:
        // 4 overloaded tys: ret, arg0, resource, sampler
        overloadTys.push_back(I.getArgOperand(0)->getType());
        overloadTys.push_back(cast<SampleIntrinsic>(&I)->getTextureValue()->getType());
        overloadTys.push_back(cast<SampleIntrinsic>(&I)->getSamplerValue()->getType());
        break;
    case GenISAIntrinsic::GenISA_ldptr:
    case GenISAIntrinsic::GenISA_ldmsptr:
        overloadTys.push_back(cast<SamplerLoadIntrinsic>(&I)->getTextureValue()->getType());
        break;
    case GenISAIntrinsic::GenISA_gather4ptr:
    case GenISAIntrinsic::GenISA_gather4Cptr:
    case GenISAIntrinsic::GenISA_gather4POptr:
    case GenISAIntrinsic::GenISA_gather4POCptr:
        // 4 overloaded tys: ret, arg0, resource, sampler
        overloadTys.push_back(I.getArgOperand(0)->getType());
        overloadTys.push_back(cast<SamplerGatherIntrinsic>(&I)->getTextureValue()->getType());
        overloadTys.push_back(cast<SamplerGatherIntrinsic>(&I)->getSamplerValue()->getType());
        break;
    default:
        return false;
    }

    Function* newSample = GenISAIntrinsic::getDeclaration(
        m_currFunction->getParent(), I.getIntrinsicID(), overloadTys);
    llvm::SmallVector<llvm::Value*, 8> newArgs;
    for (unsigned int i = 0, argSize = I.getNumArgOperands(); i < argSize; i++)
    {
        newArgs.push_back(I.getArgOperand(i));
    }
    m_builder->SetInsertPoint(&I);
    auto newCall = m_builder->CreateCall(newSample, newArgs);

    for (auto use = I.user_begin(); use != I.user_end(); ++use)
    {
        ExtractElementInst*  extractElt = cast<ExtractElementInst>(*use);
        m_builder->SetInsertPoint(extractElt);

        Value* extractUse = *extractElt->user_begin();
        Value* newExtract = m_builder->CreateExtractElement(newCall, extractElt->getIndexOperand());
        if (extractUse->getType()->isFloatingPointTy())
        {
            extractUse->replaceAllUsesWith(newExtract);
        }
        else
        {
            if (dyn_cast<TruncInst>(extractUse))
            {
                // replace trunc with new extractElt
                extractUse->replaceAllUsesWith(newExtract);
            }
            else
            {
                // replace and with zext
                Value* zextInst = m_builder->CreateZExt(newExtract, m_builder->getInt32Ty());
                extractUse->replaceAllUsesWith(zextInst);
            }
        }
    }
    return true;
}

void LowPrecisionOpt::visitIntrinsicInst(llvm::IntrinsicInst &I)
{
    if(!m_simplifyAlu)
    {
        return;
    }
    if (I.getIntrinsicID() != llvm::Intrinsic::floor ||
        I.getType() != Type::getHalfTy(m_builder->getContext()))
        return;

    auto src = I.getOperand(0);
    m_builder->SetInsertPoint(&I);

    auto fpTrunc = llvm::dyn_cast <llvm::FPTruncInst>(src);
    if (fpTrunc)
    {
        src = fpTrunc->getOperand(0);
    }
    else
    {
        src = m_builder->CreateFPExt(src, m_builder->getFloatTy());
    }

    if (!func_llvm_floor_f32)
        func_llvm_floor_f32 = llvm::Intrinsic::getDeclaration(m_currFunction->getParent(), Intrinsic::floor, m_builder->getFloatTy());

    auto floor32 = m_builder->CreateCall(func_llvm_floor_f32, src);
#if VALUE_NAME_ENABLE
    floor32->setName(I.getName());
#endif

    if (I.hasOneUse())
    {
        auto hfSub = llvm::dyn_cast<llvm::BinaryOperator>(*I.user_begin());

        if (hfSub && hfSub->getOpcode() == llvm::Instruction::BinaryOps::FSub)
        {
            if (hfSub->getOperand(0) == I.getOperand(0))
            {
                auto fSub = m_builder->CreateFSub(src, floor32, hfSub->getName());
                auto fpdst = m_builder->CreateFPTrunc(fSub, Type::getHalfTy(m_builder->getContext()));
                hfSub->replaceAllUsesWith(fpdst);
            }
        }
    }
    else
    {
        auto fpdst = m_builder->CreateFPTrunc(floor32, Type::getHalfTy(m_builder->getContext()));
        I.replaceAllUsesWith(fpdst);
        I.eraseFromParent();
    }

}

/*FP16SamplerOptimization*/
void LowPrecisionOpt::visitCallInst(CallInst &I)
{
    if(!m_changeSample)
    {
        return;
    }
    if (isSampleLoadGather4InfoInstruction(&I))
    {
        bool changed = propagateSamplerType(*cast<GenIntrinsicInst>(&I));
        if (changed)
        {
            return;
        }
    }
}
