/*===================== 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,
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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
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IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


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

#include "GenISAIntrinsics/GenIntrinsics.h"
#include "GenISAIntrinsics/GenIntrinsicInst.h"
#include "Compiler/CustomSafeOptPass.hpp"
#include "Compiler/CISACodeGen/helper.h"
#include "Compiler/CodeGenPublic.h"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/MetaDataUtilsWrapper.h"
#include "common/LLVMUtils.h"
#include "common/IGCIRBuilder.h"

#include "common/LLVMWarningsPush.hpp"
#include "common/LLVMWarningsPop.hpp"

using namespace llvm;
using namespace IGC;

//#define DEBUG_BLENDTODISCARD

namespace {

/**
 * Check sampler result and do early out using discard based on blend state.
 */
class BlendToDiscard : public FunctionPass
{
public:
    static char ID;

    BlendToDiscard() : FunctionPass(ID)
    {
        initializeBlendToDiscardPass(*PassRegistry::getPassRegistry());
    }

    void getAnalysisUsage(AnalysisUsage& AU) const override
    {
        AU.setPreservesCFG();
        AU.addRequired<CodeGenContextWrapper>();
        AU.addRequired<MetaDataUtilsWrapper>();
    }
    
    virtual llvm::StringRef getPassName() const override
    {
        return "BlendToDiscard";
    }

    bool runOnFunction(Function& F) override;
    
private:
    CodeGenContext* m_cgCtx;
    ModuleMetaData* m_modMD;
    Module* m_module;

    bool discardOnAlpha(GenIntrinsicInst* out);

    // Blend to discard opt for multiple render target writes
    bool blendToDiscardMRT(GenIntrinsicInst** outInst, unsigned nOutInsts);

    Instruction* isFMul(Value* v)
    {
        Instruction* inst = dyn_cast<Instruction>(v);
        if (inst && inst->getOpcode() == Instruction::FMul)
        {
            return inst;
        }
        return nullptr;
    }

    void createDiscard(Instruction* extract, bool check0);
};

} // namespace

char BlendToDiscard::ID = 0;

IGC_INITIALIZE_PASS_BEGIN(BlendToDiscard,
    "BlendToDiscard", "BlendToDiscard", false, false)
IGC_INITIALIZE_PASS_DEPENDENCY(CodeGenContextWrapper)
IGC_INITIALIZE_PASS_DEPENDENCY(MetaDataUtilsWrapper);
IGC_INITIALIZE_PASS_END(BlendToDiscard, 
    "BlendToDiscard", "BlendToDiscard", false, false)

FunctionPass* IGC::createBlendToDiscardPass()
{
    return new BlendToDiscard();
}

bool BlendToDiscard::runOnFunction(Function& F)
{
    const int MAX_NUM_OUTPUTS = 4;
    const int MAX_NUM_OUTPUT_VALUES = 6;

    if (!IGC_IS_FLAG_ENABLED(EnableBlendToDiscard))
    {
        return false;
    }


    // Skip non-kernel function.                                                  
    IGCMD::MetaDataUtils *mdu =
        getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();
    auto FII = mdu->findFunctionsInfoItem(&F);
    if (FII == mdu->end_FunctionsInfo())
        return false;

    m_cgCtx = getAnalysis<CodeGenContextWrapper>().getCodeGenContext();
    m_modMD = m_cgCtx->getModuleMetaData();
    m_module = F.getParent();

    assert(m_cgCtx->type == ShaderType::PIXEL_SHADER);

    std::vector<int>& blendOpt = m_modMD->psInfo.blendOptimizationMode;
    if (!blendOpt.size() || m_cgCtx->m_instrTypes.hasDiscard)
    {
        return false;
    }
    
    smallvector<GenIntrinsicInst*, 8> outInst(MAX_NUM_OUTPUTS);
    unsigned nOutInsts = 0, nOutValues = 0;

    for (auto& BI : F)
    {
        for (auto& II : BI)
        {
            GenIntrinsicInst* out = dyn_cast<GenIntrinsicInst>(
                &II, GenISAIntrinsic::GenISA_OUTPUT);

            if (out)
            {
                assert(isa<ConstantInt>(out->getOperand(4)) &&
                    isa<ConstantInt>(out->getOperand(5)));

                ShaderOutputType oType = static_cast<ShaderOutputType>(
                    out->getImm64Operand(4));
                unsigned rtIdx = static_cast<unsigned>(
                    out->getImm64Operand(5));

                if (rtIdx >= MAX_NUM_OUTPUTS ||
                    blendOpt[rtIdx] == USC::BLEND_OPTIMIZATION_NONE ||
                    blendOpt[rtIdx] == USC::BLEND_OPTIMIZATION_SRC_ALPHA_FILL_ONLY)
                {
                    return false;
                }

                if (oType == SHADER_OUTPUT_TYPE_DEFAULT)
                {
                    outInst[rtIdx] = out;
                    nOutInsts++;

                    if (nOutInsts >= MAX_NUM_OUTPUTS)
                    {
                        return false;
                    }

                    for (unsigned i = 0; i < 4; i++)
                    {
                        if (!isa<UndefValue>(out->getOperand(i)))
                        {
                            nOutValues++;
                        }
                    }

                    if (nOutValues > MAX_NUM_OUTPUT_VALUES)
                    {
                        return false;
                    }
                }
            }
        }
    }

    bool changed = false;
    if (nOutInsts == 1 && outInst[0] != nullptr)
    {
        changed = discardOnAlpha(outInst[0]);
    }
    else
    if (nOutInsts == 2 && outInst[0] != nullptr && outInst[1] != nullptr)
    {
        changed = blendToDiscardMRT(outInst.data(), nOutInsts);
    }

#ifdef DEBUG_BLENDTODISCARD
    if (changed)
    {
        DumpLLVMIR(m_cgCtx, "blendtodiscard");
    }
#endif

    return changed;
}

bool BlendToDiscard::discardOnAlpha(GenIntrinsicInst* out)
{
    Instruction* alpha = isFMul(out->getArgOperand(3));
    bool check0;
    bool changed = false;

    if (m_modMD->psInfo.blendOptimizationMode.size() == 0)
        return false;

    switch (m_modMD->psInfo.blendOptimizationMode[0])
    {
    case USC::BLEND_OPTIMIZATION_SRC_ALPHA:
    case USC::BLEND_OPTIMIZATION_SRC_ALPHA_DISCARD_ONLY:
        check0 = true;
        break;

    case USC::BLEND_OPTIMIZATION_INV_SRC_ALPHA:
        check0 = false;
        break;

    default:
        return false;
    }

    if (alpha)
    {
        // search back all fmul for sample result
        std::vector<Instruction*> opnds;
        SmallPtrSet<Value*, 32> visited;
        unsigned li = 0;

        opnds.push_back(alpha);
        visited.insert(alpha);

        while (li < opnds.size())
        {
            Instruction* inst = opnds[li];
            li++;

            for (unsigned i = 0; i < inst->getNumOperands(); i++)
            {
                Value* v = inst->getOperand(i);

                if (visited.count(v))
                {
                    continue;
                }

                if (ExtractElementInst* extract = dyn_cast<ExtractElementInst>(v))
                {
                    GenIntrinsicInst* intrin = dyn_cast<GenIntrinsicInst>(
                        extract->getVectorOperand());
                    if (intrin && isSampleInstruction(intrin))
                    {
                        createDiscard(extract, check0);
                        m_modMD->psInfo.forceEarlyZ = true;
                        changed = true;
                        return changed;
                    }
                }

                Instruction* fmul = isFMul(v);
                if (fmul && !visited.count(fmul))
                {
                    opnds.push_back(fmul);
                }

                visited.insert(v);
            }
        }
    }
    
    return changed;
}

void BlendToDiscard::createDiscard(Instruction* extract, bool check0)
{
    if (extract != nullptr)
    {
        Function* fDiscard = GenISAIntrinsic::getDeclaration(m_module,
            GenISAIntrinsic::GenISA_discard);

        IRBuilder<> irb(extract->getNextNode());
        Value* cond;
        if (check0)
        {
            // check against 0
            cond = irb.CreateFCmpOEQ(extract, ConstantFP::get(extract->getType(), 0.0));
        }
        else
        {
            // check against 1
            cond = irb.CreateFCmpOEQ(extract, ConstantFP::get(extract->getType(), 1.0));
        }
        irb.CreateCall(fDiscard, { cond });
    }
}

bool BlendToDiscard::blendToDiscardMRT(
    GenIntrinsicInst** outInst, unsigned nOutInsts)
{
    IGCIRBuilder<> irb(outInst[0]);
    std::vector<int>& blendOpt = m_modMD->psInfo.blendOptimizationMode;

    Value* discardCond = nullptr;
    for (unsigned i = 0; i < 2; i++)
    {
        Value* colors[4] = { nullptr };
        unsigned nValues = 0, nColors = 0;

        for (unsigned j = 0; j < 4; j++)
        {
            if (!isa<UndefValue>(outInst[i]->getOperand(j)))
            {
                colors[nValues] = outInst[i]->getOperand(j);
                nValues++;
                if (j != 3)
                {
                    nColors++;
                }
            }
        }

        Value* cond;
        Value* alpha = outInst[i]->getOperand(3);
        Value* f0 = ConstantFP::get(alpha->getType(), 0.0);
        Value* f1 = ConstantFP::get(alpha->getType(), 1.0);
        switch (blendOpt[i])
        {
        case USC::BLEND_OPTIMIZATION_SRC_ALPHA:
        case USC::BLEND_OPTIMIZATION_SRC_ALPHA_DISCARD_ONLY:
            // discard: src.a == 0
            cond = irb.CreateFCmpOEQ(alpha, f0);
            break;

        case USC::BLEND_OPTIMIZATION_INV_SRC_ALPHA:
            // discard: src.a == 1
            cond = irb.CreateFCmpOEQ(alpha, f1);
            break;

        case USC::BLEND_OPTIMIZATION_SRC_COLOR_ZERO:
            // discard: src.rgb == 0
            cond = irb.CreateAllValuesAreZeroF(colors, nColors);
            break;

        case USC::BLEND_OPTIMIZATION_SRC_COLOR_ONE:
            // discard if src.rgb == 1
            cond = irb.CreateAllValuesAreOneF(colors, nColors);
            break;

        case USC::BLEND_OPTIMIZATION_SRC_BOTH_ZERO:
            // discard: src.rgba == 0
            cond = irb.CreateAllValuesAreZeroF(colors, nValues);
            break;

        case USC::BLEND_OPTIMIZATION_SRC_BOTH_ONE:
            // discard if src.rgba == 1
            cond = irb.CreateAllValuesAreOneF(colors, nValues);
            break;

        case USC::BLEND_OPTIMIZATION_SRC_ALPHA_OR_COLOR_ZERO:
            // discard: src.a == 0 || src.rgb == 0
            cond = irb.CreateOr(
                irb.CreateFCmpOEQ(alpha, f0),
                irb.CreateAllValuesAreZeroF(colors, nColors));
            break;

        case USC::BLEND_OPTIMIZATION_SRC_COLOR_ZERO_ALPHA_ONE:
            // discard: src.rgb == 0 && src.a == 1
            cond = irb.CreateAnd(
                irb.CreateFCmpOEQ(alpha, f1),
                irb.CreateAllValuesAreZeroF(colors, nColors));
            break;

        case USC::BLEND_OPTIMIZATION_SRC_COLOR_ZERO_ALPHA_IGNORE:
        {
            // Discard: src.rgb == 0 and don't compute src.a
            cond = irb.CreateAllValuesAreZeroF(colors, nColors);
            Value* nAlpha = IGC_IS_FLAG_ENABLED(EnableUndefAlphaOutputAsRed) ?
                outInst[i]->getOperand(0) : f0;

            outInst[i]->setOperand(3, nAlpha);
            break;
        }

        default:
            assert(false && "Need to handle more cases");
        }

        if (discardCond)
        {
            discardCond = irb.CreateAnd(discardCond, cond);
        }
        else
        {
            discardCond = cond;
        }
    }

    Function* fDiscard = GenISAIntrinsic::getDeclaration(m_module,
        GenISAIntrinsic::GenISA_discard);

    irb.CreateCall(fDiscard, { discardCond });

    return true;
}
