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

Copyright (C) 2017-2021 Intel Corporation

SPDX-License-Identifier: MIT

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

#include "Compiler/CISACodeGen/Simd32Profitability.hpp"
#include "Compiler/CodeGenPublic.h"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/CISACodeGen/Platform.hpp"
#include "common/LLVMWarningsPush.hpp"
#include <llvmWrapper/IR/ConstantFold.h>
#include <llvmWrapper/IR/DerivedTypes.h>
#include <llvmWrapper/Transforms/Utils/LoopUtils.h>
#include <llvm/IR/InstIterator.h>
#include <llvm/IR/Operator.h>
#include <llvmWrapper/IR/DerivedTypes.h>
#include <llvm/Support/CommandLine.h>
#include "common/LLVMWarningsPop.hpp"
#include "GenISAIntrinsics/GenIntrinsics.h"
#include "GenISAIntrinsics/GenIntrinsicInst.h"
#include "Probe/Assertion.h"

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

// Register pass to igc-opt
#define PASS_FLAG "simd32-profit"
#define PASS_DESCRIPTION "Check SIMD32 Profitability for OpenCL"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS true
IGC_INITIALIZE_PASS_BEGIN(Simd32ProfitabilityAnalysis, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(WIAnalysis)
IGC_INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
IGC_INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
IGC_INITIALIZE_PASS_DEPENDENCY(MetaDataUtilsWrapper)
IGC_INITIALIZE_PASS_END(Simd32ProfitabilityAnalysis, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)

static cl::opt<bool> enableProfitabilityPrint(
    "enable-profitability-print", cl::init(false), cl::Hidden,
    cl::desc("Enable m_isSimd32Profitable/m_isSimd16Profitable fields print"));

char Simd32ProfitabilityAnalysis::ID = 0;

const unsigned BRANCHY_MINPATH = 8;

Simd32ProfitabilityAnalysis::Simd32ProfitabilityAnalysis()
    : FunctionPass(ID), F(nullptr), PDT(nullptr), LI(nullptr),
    pMdUtils(nullptr), WI(nullptr), m_isSimd32Profitable(true),
    m_isSimd16Profitable(true) {
    initializeSimd32ProfitabilityAnalysisPass(*PassRegistry::getPassRegistry());
}

static std::tuple<Value* /*INIT*/, Value* /*CURR*/, Value* /*STEP*/, Value* /*NEXT*/>
getInductionVariable(Loop* L) {
    BasicBlock* H = L->getHeader();

    BasicBlock* Incoming = 0, *Backedge = 0;
    pred_iterator PI = pred_begin(H);
    IGC_ASSERT_MESSAGE(PI != pred_end(H), "Loop must have at least one backedge!");
    Backedge = *PI++;
    if (PI == pred_end(H)) // dead loop
        return std::make_tuple(nullptr, nullptr, nullptr, nullptr);
    Incoming = *PI++;
    if (PI != pred_end(H)) // multiple backedges?
        return std::make_tuple(nullptr, nullptr, nullptr, nullptr);

    if (L->contains(Incoming)) {
        if (L->contains(Backedge))
            return std::make_tuple(nullptr, nullptr, nullptr, nullptr);
        std::swap(Incoming, Backedge);
    }
    else if (!L->contains(Backedge))
        return std::make_tuple(nullptr, nullptr, nullptr, nullptr);

    // Loop over all of the PHI nodes, looking for an indvar.
    for (auto I = H->begin(); isa<PHINode>(I); ++I) {
        PHINode* PN = cast<PHINode>(I);
        if (auto Inc = dyn_cast<Instruction>(PN->getIncomingValueForBlock(Backedge))) {
            if (Inc->getOpcode() == Instruction::Add && Inc->getOperand(0) == PN) {
                return
                    std::make_tuple(PN->getIncomingValueForBlock(Incoming), PN,
                        Inc->getOperand(1), Inc);
            }
        }
    }

    return std::make_tuple(nullptr, nullptr, nullptr, nullptr);
}

enum {
    LOOPCOUNT_LIKELY_SMALL,
    LOOPCOUNT_LIKELY_LARGE,
    LOOPCOUNT_UNKNOWN
};

static bool isSignedPredicate(CmpInst::Predicate Pred) {
    switch (Pred) {
    default: break;
    case CmpInst::ICMP_EQ:
    case CmpInst::ICMP_NE:
    case CmpInst::ICMP_SGT:
    case CmpInst::ICMP_SLT:
    case CmpInst::ICMP_SGE:
    case CmpInst::ICMP_SLE:
        return true;
    }
    return false;
}

static bool isUnsignedPredicate(CmpInst::Predicate Pred) {
    switch (Pred) {
    default: break;
    case CmpInst::ICMP_EQ:
    case CmpInst::ICMP_NE:
    case CmpInst::ICMP_UGT:
    case CmpInst::ICMP_ULT:
    case CmpInst::ICMP_UGE:
    case CmpInst::ICMP_ULE:
        return true;
    }
    return false;
}

static bool hasSameSignedness(CmpInst::Predicate LHS, CmpInst::Predicate RHS) {
    if (isSignedPredicate(LHS) && isSignedPredicate(RHS))
        return true;
    if (isUnsignedPredicate(LHS) && isUnsignedPredicate(RHS))
        return true;
    return false;
}

static std::tuple<Value*, Value*, Value*, bool>
isOutOfRangeComparison(Value* Cond) {
    BinaryOperator* BO = dyn_cast<BinaryOperator>(Cond);
    if (!BO || BO->getOpcode() != Instruction::Or)
        return std::make_tuple(nullptr, nullptr, nullptr, false);

    ICmpInst* LHS = dyn_cast<ICmpInst>(BO->getOperand(0));
    ICmpInst* RHS = dyn_cast<ICmpInst>(BO->getOperand(1));

    if (!LHS || !RHS)
        return std::make_tuple(nullptr, nullptr, nullptr, false);

    CmpInst::Predicate P0 = LHS->getPredicate();
    CmpInst::Predicate P1 = RHS->getPredicate();

    if (!hasSameSignedness(P0, P1))
        return std::make_tuple(nullptr, nullptr, nullptr, false);

    // Simplify the checking since they have the same signedness.
    P0 = ICmpInst::getSignedPredicate(P0);
    P1 = ICmpInst::getSignedPredicate(P1);

    if (!(P0 == CmpInst::ICMP_SLT || P0 == CmpInst::ICMP_SLE)) {
        std::swap(LHS, RHS);
        std::swap(P0, P1);
    }
    if (!(P0 == CmpInst::ICMP_SLT || P0 == CmpInst::ICMP_SLE) ||
        !(P1 == CmpInst::ICMP_SGT || P1 == CmpInst::ICMP_SGE))
        return std::make_tuple(nullptr, nullptr, nullptr, false);

    if (LHS->getOperand(0) != RHS->getOperand(0))
        return std::make_tuple(nullptr, nullptr, nullptr, false);

    return std::make_tuple(LHS->getOperand(0),
        LHS->getOperand(1), RHS->getOperand(1),
        isSignedPredicate(LHS->getPredicate()));
}

static Value* getLoopCounter(Loop* L, Value* X) {
    BasicBlock* H = L->getHeader();

    BasicBlock* Incoming = 0, *Backedge = 0;
    pred_iterator PI = pred_begin(H);
    IGC_ASSERT_MESSAGE(PI != pred_end(H), "Loop must have at least one backedge!");
    Backedge = *PI++;
    if (PI == pred_end(H)) // dead loop
        return nullptr;
    Incoming = *PI++;
    if (PI != pred_end(H)) // multiple backedges?
        return nullptr;

    if (L->contains(Incoming)) {
        if (L->contains(Backedge))
            return nullptr;
        std::swap(Incoming, Backedge);
    }
    else if (!L->contains(Backedge))
        return nullptr;

    for (auto I = H->begin(); isa<PHINode>(I); ++I) {
        PHINode* PN = cast<PHINode>(I);
        if (X == PN->getIncomingValueForBlock(Backedge))
            return PN;
    }

    return nullptr;
}

static std::tuple<int, int>
countOperands(Value* V, Value* LHS, Value* RHS) {
    if (V == LHS || V == RHS)
        return std::make_tuple((V == LHS), (V == RHS));

    // Count LHS, RHS in an expression like m*L + n*R +/- C, where C is
    // constant.
    BinaryOperator* BO = dyn_cast<BinaryOperator>(V);
    if (!BO ||
        (BO->getOpcode() != Instruction::Add &&
            BO->getOpcode() != Instruction::Sub &&
            BO->getOpcode() != Instruction::Shl &&
            BO->getOpcode() != Instruction::Xor))
        return std::make_tuple(0, 0);

    if (BO->getOpcode() == Instruction::Shl) {
        ConstantInt* CI = dyn_cast<ConstantInt>(BO->getOperand(1));
        if (!CI)
            return std::make_tuple(0, 0);
        auto [L, R] = countOperands(BO->getOperand(0), LHS, RHS);
        uint64_t ShAmt = CI->getZExtValue();
        return std::make_tuple((L << ShAmt), (R << ShAmt));
    }

    if (BO->getOpcode() == Instruction::Xor) {
        ConstantInt* CI = dyn_cast<ConstantInt>(BO->getOperand(1));
        if (!CI || CI->getSExtValue() != -1)
            return std::make_tuple(0, 0);
        auto [L, R] = countOperands(BO->getOperand(0), LHS, RHS);
        return std::make_tuple(-L, -R);
    }


    IGC_ASSERT((BO->getOpcode() == Instruction::Add) || (BO->getOpcode() == Instruction::Sub));

    if (isa<Constant>(BO->getOperand(1)))
        return countOperands(BO->getOperand(0), LHS, RHS);
    auto [L0, L1] = countOperands(BO->getOperand(0), LHS, RHS);
    auto [R0, R1] = countOperands(BO->getOperand(1), LHS, RHS);
    if (BO->getOpcode() == Instruction::Add)
        return std::make_tuple(L0 + R0, L1 + R1);

    IGC_ASSERT(BO->getOpcode() == Instruction::Sub);
    return std::make_tuple(L0 - R0, L1 - R1);
}

static bool isNegatedByLB(Value* V, Value* X, Value* LB) {
    // Check if `V` is calculated as LB - X +/- C, where C is constant.
    auto [L, R] = countOperands(V, LB, X);
    return (L == 1) && (R == -1);
}

static bool isNegatedBy2UB(Value* V, Value* X, Value* UB) {
    // Check if `V` is calculated as 2UB - X +/- C, where C is constant.
    auto [L, R] = countOperands(V, UB, X);
    return (L == 2) && (R == -1);
}

unsigned Simd32ProfitabilityAnalysis::estimateLoopCount_CASE1(Loop* L) {
    BasicBlock* Exit = L->getExitingBlock();
    if (!Exit)
        return LOOPCOUNT_UNKNOWN;

    BranchInst* Br = dyn_cast<BranchInst>(Exit->getTerminator());
    if (!Br || !Br->isConditional())
        return LOOPCOUNT_UNKNOWN;
    if (!L->contains(Br->getSuccessor(0)))
        return LOOPCOUNT_UNKNOWN;

    auto [X, LB, UB, Signed] = isOutOfRangeComparison(Br->getCondition());
    if (!X) {
        ICmpInst* Cmp = dyn_cast<ICmpInst>(Br->getCondition());
        if (!Cmp)
            return LOOPCOUNT_UNKNOWN;
        switch (Cmp->getPredicate()) {
        default:
            return LOOPCOUNT_UNKNOWN;
        case CmpInst::ICMP_UGT:
        case CmpInst::ICMP_UGE:
            // A smart use of unsigned comparison on signed values to perform a
            // out-of-range change of (0, N).
            break;
        }
        X = Cmp->getOperand(0);
        LB = Constant::getNullValue(X->getType());
        UB = Cmp->getOperand(1);
        Signed = true;
    }

    Value* LC = getLoopCounter(L, X);
    if (!LC)
        return LOOPCOUNT_UNKNOWN;

    if (PHINode * PN = dyn_cast<PHINode>(X)) {
        if (PN->getNumIncomingValues() != 2)
            return LOOPCOUNT_UNKNOWN;
        BasicBlock* BB0 = PN->getIncomingBlock(0);
        BasicBlock* IfBB = BB0->getSinglePredecessor();
        if (!IfBB)
            return LOOPCOUNT_UNKNOWN;
        Br = dyn_cast<BranchInst>(IfBB->getTerminator());
        if (!Br || !Br->isConditional())
            return LOOPCOUNT_UNKNOWN;
        ICmpInst* Cmp = dyn_cast<ICmpInst>(Br->getCondition());
        if (!Cmp)
            return LOOPCOUNT_UNKNOWN;
        CmpInst::Predicate Pred = Cmp->getPredicate();
        Value* LHS = Cmp->getOperand(0);
        Value* RHS = Cmp->getOperand(1);
        if (LHS != LC) {
            std::swap(LHS, RHS);
            Pred = CmpInst::getSwappedPredicate(Pred);
        }
        if (LHS != LC)
            return LOOPCOUNT_UNKNOWN;
        if (!Signed)
            Pred = ICmpInst::getSignedPredicate(Pred);
        if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_SLE)
            return LOOPCOUNT_UNKNOWN;
        if (RHS != LB)
            return LOOPCOUNT_UNKNOWN;

        Value* X0 = PN->getIncomingValue(0);
        Value* X1 = PN->getIncomingValue(1);
        if (!isNegatedByLB(X0, LC, LB))
            return LOOPCOUNT_UNKNOWN;
        if (!isNegatedBy2UB(X1, LC, UB))
            return LOOPCOUNT_UNKNOWN;
    }
    else if (BinaryOperator * BO = dyn_cast<BinaryOperator>(X)) {
        if (BO->getOpcode() != Instruction::Sub)
            return LOOPCOUNT_UNKNOWN;
        if (BO->getOperand(1) != LC)
            return LOOPCOUNT_UNKNOWN;
        SelectInst* SI = dyn_cast<SelectInst>(BO->getOperand(0));
        if (!SI)
            return LOOPCOUNT_UNKNOWN;
        ICmpInst* Cmp = dyn_cast<ICmpInst>(SI->getCondition());
        if (!Cmp)
            return LOOPCOUNT_UNKNOWN;
        CmpInst::Predicate Pred = Cmp->getPredicate();
        Value* LHS = Cmp->getOperand(0);
        Value* RHS = Cmp->getOperand(1);
        if (LHS != LC) {
            std::swap(LHS, RHS);
            Pred = CmpInst::getSwappedPredicate(Pred);
        }
        if (LHS != LC)
            return LOOPCOUNT_UNKNOWN;
        if (!Signed)
            Pred = ICmpInst::getSignedPredicate(Pred);
        Value* X0 = SI->getTrueValue();
        Value* X1 = SI->getFalseValue();
        if (Pred == CmpInst::ICMP_SGT || Pred == CmpInst::ICMP_SGE) {
            std::swap(X0, X1);
            Pred = CmpInst::getInversePredicate(Pred);
        }
        if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_SLE)
            return LOOPCOUNT_UNKNOWN;
        if (RHS != LB)
            return LOOPCOUNT_UNKNOWN;
        auto [L0, R0] = countOperands(X0, LB, nullptr);
        auto [L1, R1] = countOperands(X1, UB, nullptr);
        if (L0 != 1 || L1 != 2)
            return LOOPCOUNT_UNKNOWN;
    }
    else
        return LOOPCOUNT_UNKNOWN;

    // Ok, we found a loop of the following pattern:
    //
    // do {
    //   if (x < 0) {
    //      x = 0 - x +/- c0;
    //   } else {
    //      x = 2 * UB - x +/- c1;
    //   }
    // } while (x < LB || x > UB);
    //
    // such loop will run only once or twice when non-arbitary large `x`. If a
    // non-uniform loop only runs several iterations, divergence cost due to
    // SIMD32 could be ignored.
    return LOOPCOUNT_LIKELY_SMALL;
}

unsigned Simd32ProfitabilityAnalysis::estimateLoopCount_CASE2(Loop* L) {
    SmallVector<BasicBlock*, 8> ExitingBBs;
    L->getExitingBlocks(ExitingBBs);

    auto [Init, Curr, Step, Next] = getInductionVariable(L);
    if (!Init || !Curr || !Step || !Next)
        return LOOPCOUNT_UNKNOWN;
    ConstantInt* I0 = dyn_cast<ConstantInt>(Init);
    ConstantInt* S0 = dyn_cast<ConstantInt>(Step);
    if (!I0 || !S0)
        return LOOPCOUNT_UNKNOWN;

    for (auto BB : ExitingBBs) {
        BranchInst* Br = dyn_cast<BranchInst>(BB->getTerminator());
        if (!Br || !Br->isConditional())
            continue;
        if (!L->contains(Br->getSuccessor(0))) // Not condition of `continue`.
            continue;
        ICmpInst* Cmp = dyn_cast<ICmpInst>(Br->getCondition());
        if (!WI->isUniform(Br)) {
            BinaryOperator* BO = dyn_cast<BinaryOperator>(Br->getCondition());
            if (!BO)
                continue;
            if (BO->getOpcode() != Instruction::And)
                continue;
            ICmpInst* Cond = nullptr;
            ICmpInst* Op0 = dyn_cast<ICmpInst>(BO->getOperand(0));
            if (Op0 && WI->isUniform(Op0))
                Cond = Op0;
            if (!Cond) {
                ICmpInst* Op1 = dyn_cast<ICmpInst>(BO->getOperand(1));
                if (Op1 && WI->isUniform(Op1))
                    Cond = Op1;
            }
            if (!Cond)
                continue;
            Cmp = Cond;
        }
        if (!Cmp)
            continue;
        CmpInst::Predicate Pred = Cmp->getPredicate();
        switch (Pred) {
        default:
            // TODO: Handle more predicates.
            continue;
        case ICmpInst::ICMP_SLT:
        case ICmpInst::ICMP_ULT:
            break;
        }
        Value* Op0 = Cmp->getOperand(0);
        Value* Op1 = Cmp->getOperand(1);
        if (Op0 != Next)
            continue;
        ConstantInt* E0 = dyn_cast<ConstantInt>(Op1);
        if (!E0)
            continue;
        unsigned OpCode = Pred == ICmpInst::ICMP_SLT ? Instruction::SDiv
                                                     : Instruction::UDiv;
        ConstantInt* N = dyn_cast<ConstantInt>(
            IGCLLVM::ConstantFoldBinaryInstruction(
                OpCode, ConstantExpr::getSub(E0, I0), S0));
        if (!N)
            continue;
        if (N->getValue().slt(0))
            continue;
        if (N->getValue().slt(100))
            return LOOPCOUNT_LIKELY_SMALL;
    }

    // Ok, we found a non-uniform loop with multiple exiting conditions.
    // However, one of them is uniform one and has small loop count.
    return LOOPCOUNT_UNKNOWN;
}

unsigned Simd32ProfitabilityAnalysis::estimateLoopCount(Loop* L) {
    unsigned Ret;

    Ret = estimateLoopCount_CASE1(L);
    if (Ret != LOOPCOUNT_UNKNOWN)
        return Ret;

    Ret = estimateLoopCount_CASE2(L);
    if (Ret != LOOPCOUNT_UNKNOWN)
        return Ret;

    return Ret;
}

static Value* getLoopCount(Value* Start, Value* End) {
    // Poorman's loop count checking as we need to check that result with WIA.
    ConstantInt* CStart = dyn_cast<ConstantInt>(Start);
    ConstantInt* CEnd = dyn_cast<ConstantInt>(End);
    if (CStart && CEnd)
        return ConstantExpr::getSub(CEnd, CStart);

    if (CStart && CStart->isNullValue())
        return End;

    BinaryOperator* BO = dyn_cast<BinaryOperator>(End);
    if (!BO || BO->getOpcode() != Instruction::Add)
        return nullptr;

    Value* Op0 = BO->getOperand(0);
    Value* Op1 = BO->getOperand(1);
    if (Op0 != Start)
        std::swap(Op0, Op1);
    if (Op0 == Start)
        return Op1;

    return nullptr;
}

/// hasIEEESqrtOrDivFunc - Check whether IEEE correctly-rounded SQRT or DIV is
/// used in the given function.
static bool hasIEEESqrtOrDivFunc(const Function& F) {
    for (auto& BB : F)
        for (auto& I : BB) {
            const GenIntrinsicInst* GII = dyn_cast<GenIntrinsicInst>(&I);
            if (!GII)
                continue;
            switch (GII->getIntrinsicID()) {
            case GenISAIntrinsic::GenISA_IEEE_Sqrt:
            case GenISAIntrinsic::GenISA_IEEE_Divide:
                return true;
            default: break;
            }
        }
    return false;
}

/// hasSubGroupFunc - Check whether subgroup functions are used in the given
/// function.
static bool hasSubGroupFunc(const Function& F)
{
    for (auto& BB : F)
    {
        for (auto& I : BB)
        {
            if (isSubGroupIntrinsic(&I))
            {
                return true;
            }
        }
    }

    return false;
}

bool Simd32ProfitabilityAnalysis::runOnFunction(Function& F)
{
    this->F = &F;
    CodeGenContext* context = nullptr;
    context = getAnalysis<CodeGenContextWrapper>().getCodeGenContext();
    if (context->type == ShaderType::OPENCL_SHADER)
    {
        PDT = &getAnalysis<PostDominatorTreeWrapperPass>().getPostDomTree();
        LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
        WI = &getAnalysis<WIAnalysis>();
        pMdUtils = getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();
        m_isSimd16Profitable = checkSimd16Profitable(context);
        m_isSimd32Profitable = m_isSimd16Profitable && checkSimd32Profitable(context);
    }
    else if (context->type == ShaderType::PIXEL_SHADER)
    {
        LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
        m_isSimd32Profitable = checkPSSimd32Profitable();
    }

    if (enableProfitabilityPrint)
      print(IGC::Debug::ods());

    return false;
}

void Simd32ProfitabilityAnalysis::print(llvm::raw_ostream& OS) const
{
    OS << "\nisSimd16Profitable: " << m_isSimd16Profitable;
    OS << "\nisSimd32Profitable: " << m_isSimd32Profitable << "\n\n";
}

bool Simd32ProfitabilityAnalysis::checkSimd32Profitable(CodeGenContext* ctx)
{
    // If a kernel is too big, it would probably have enough work for EUs
    // even without simd32; and simd32 would have more visa variables than
    // 64K limit (ocl c99 64 bit PrintHalf/half8.c for example); thus make
    // sense to skip simd32.
    size_t programSizeLimit = 8000;
    size_t programSize = 0;
    for (Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI)
    {
        BasicBlock* BB = &*FI;
        programSize += BB->size();
    }
    ctx->metrics.CollectInstructionCnt(F, programSize, programSizeLimit);
    if (programSize > programSizeLimit)
    {
        return false;
    }

    // If we have workgroup size (or workgroup size hint) metadata, check whether the X dimension
    // is expected to be of size 16 or below. If it is, no point in using SIMD32, we'll just
    // get empty lanes.
    auto funcInfoMD = pMdUtils->findFunctionsInfoItem(F);
    if (funcInfoMD != pMdUtils->end_FunctionsInfo())
    {
        ThreadGroupSizeMetaDataHandle tgSize = funcInfoMD->second->getThreadGroupSize();
        ThreadGroupSizeMetaDataHandle tgSizeHint = funcInfoMD->second->getThreadGroupSizeHint();
        const int tgSizeLimit = 16;
        int tgSizeCal = tgSize->getXDim() * tgSize->getYDim() * tgSize->getZDim();
        int tgSizeHintCal = tgSizeHint->getXDim() * tgSizeHint->getYDim() * tgSizeHint->getZDim();

        ctx->metrics.CollectThreadGroupSize(F, tgSizeCal, tgSizeLimit);
        ctx->metrics.CollectThreadGroupSizeHint(F, tgSizeHintCal, tgSizeLimit);

        if (ctx->getModuleMetaData()->csInfo.maxWorkGroupSize && ctx->getModuleMetaData()->csInfo.maxWorkGroupSize <= tgSizeLimit)
            return false;

        if ((tgSize->hasValue() && tgSizeCal <= tgSizeLimit) ||
            (tgSizeHint->hasValue() && tgSizeHintCal <= tgSizeLimit)) {
            return false;
        }
    }

    // WORKAROUND - Skip SIMD32 if subgroup functions are present.
    bool hasSubGrFunc = hasSubGroupFunc(*F);
    ctx->metrics.CollectIsSubGroupFuncIn(F, hasSubGrFunc);
    if (hasSubGrFunc) {
        return false;
    }

    const CPlatform* platform = &ctx->platform;
    switch (platform->GetPlatformFamily()) {
    case IGFX_GEN9_CORE:
        /* TODO: Try to apply for platform->getPlatformInfo().eProductFamily ==
         * IGFX_BROXTON only. */
         // FALL THROUGH
    case IGFX_GEN10_CORE:
        if (hasIEEESqrtOrDivFunc(*F)) {
            ctx->metrics.CollectGen9Gen10WithIEEESqrtDivFunc(F, true);
            return false;
        }
        break;
    default:
        break;
    }
    ctx->metrics.CollectGen9Gen10WithIEEESqrtDivFunc(F, false);
    // END OF WORKAROUND

    // Ok, that's not the case.
    // Now, check whether we have any non-uniform loops.
    // The idea is that if there are divergenet loops, then SIMD32 will be harmful,
    // because we'll waste time running loops with very few full lanes.
    // If there are no divergent loops, SIMD32 is worth a shot. It still may not
    // be selected, due to spills.
    for (LoopInfo::iterator li = LI->begin(), le = LI->end(); li != le; ++li) {
        llvm::Loop* loop = *li;

        SmallVector<BasicBlock*, 8> exitingBlocks;
        loop->getExitingBlocks(exitingBlocks);

        bool AllUniform = true;
        for (auto BBI = exitingBlocks.begin(), BBE = exitingBlocks.end(); BBI != BBE; ++BBI) {
            BasicBlock* block = *BBI;

            Instruction* term = block->getTerminator();
            if (!WI->isUniform(term)) {
                auto Br = dyn_cast<BranchInst>(term);
                // Check special case for non-uniform loop where, except the
                // initial, current, and next values, STEP and COUNT are
                // uniform. In such a case, the loop is only diverged at the
                // termination. It should be still profitable to be compiled
                // into SIMD32 mode.
                if (Br && Br->isConditional()) {
                    auto ICmp = dyn_cast<ICmpInst>(Br->getCondition());
                    if (ICmp) {
                        auto [Init, Curr, Step, Next] = getInductionVariable(loop);
                        if (Init && Curr && Next && Step &&
                            WI->isUniform(Step)) {
                            auto Op0 = ICmp->getOperand(0);
                            auto Op1 = ICmp->getOperand(1);
                            if (SExtInst *SI0 = dyn_cast<SExtInst>(Op0))
                                Op0 = SI0->getOperand(0);
                            if (SExtInst *SI1 = dyn_cast<SExtInst>(Op1))
                                Op1 = SI1->getOperand(0);
                            if (Op0 != Next && Op0 != Curr)
                                std::swap(Op0, Op1);
                            // Skip non-uniform loop which only terminates on
                            // comparison between non-uniform induction variable
                            // and uniform value.
                            if (Op0 == Next || Op0 == Curr) {
                                // TODO: Need to check whether Init is linear to
                                // global/local ID. However, that checking is not
                                // that straightforward before code emitter.
                                if (WI->isUniform(Op1))
                                    continue;
                                // TODO: Eable IndVarSimplify to simlify the
                                // following check.
                                if (Value * Count = getLoopCount(Init, Op1)) {
                                    if (WI->isUniform(Count))
                                        continue;
                                }
                            }
                        }
                    }
                }
                AllUniform = false;
                break;
            }
        }
        if (!AllUniform) {
            unsigned int estLoopCnt = estimateLoopCount(loop);
            switch (estLoopCnt) {
            case LOOPCOUNT_LIKELY_LARGE:
            case LOOPCOUNT_UNKNOWN:
                ctx->metrics.CollectNonUniformLoop(F, estLoopCnt, loop);
                return false;
            case LOOPCOUNT_LIKELY_SMALL:
                break;
            }
        }
    }
    ctx->metrics.CollectNonUniformLoop(F, LOOPCOUNT_LIKELY_SMALL, nullptr);

    return true;
}

/// Cyclomatic complexity measures of the number of linearly independent paths
/// through a region.
///
/// M = a * E - N + 2 where
/// E = the number of edges of the graph
/// N = the number of nodes of the graph
/// a = scalar factor (1 for uniform branches).
///
/// We focus on loops instead of the entire program, since cyclomatic
/// complexity is roughly linear when concatenating two programs, i.e.
/// CC(F # G) = (E1 + E2 + 1) - (N1 + N2) + 2
///           = (E1 - N1 + 2) + (E2 - N2 + 2) - 1
///           = CC(F) + CC(G) - 1.
///
static const unsigned CYCLOMATIC_COMPLEXITY_THRESHOLD = 200;

unsigned Simd32ProfitabilityAnalysis::getLoopCyclomaticComplexity() {
    unsigned MaxCC = 0;
    for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) {
        Loop* L = *I;
        unsigned CC = 2;
        for (auto BI = L->block_begin(), BE = L->block_end(); BI != BE; ++BI) {
            BasicBlock* BB = *BI;
            IGCLLVM::TerminatorInst* TI = BB->getTerminator();
            bool IsUniform = WI->isUniform(TI);
            CC += TI->getNumSuccessors() * (IsUniform ? 1 : 2);
        }
        CC -= L->getNumBlocks();
        MaxCC = std::max(CC, MaxCC);
    }
    return MaxCC;
}

static unsigned getNumOfNonUniformExits(Loop* L, WIAnalysis* WI) {
    SmallVector<BasicBlock*, 8> ExistingBlocks;
    L->getExitingBlocks(ExistingBlocks);
    unsigned Count = 0;
    for (auto BB : ExistingBlocks) {
        IGCLLVM::TerminatorInst* TI = BB->getTerminator();
        bool IsUniform = WI->isUniform(TI);
        Count += !IsUniform;
    }

    return Count;
}

/// Check if a loop or its subloop has multiple non-uniform exists.
static bool hasMultipleExits(Loop* L, WIAnalysis* WI) {
    if (getNumOfNonUniformExits(L, WI) > 1)
        return true;
    for (auto InnerL : L->getSubLoops())
        if (hasMultipleExits(InnerL, WI))
            return true;
    return false;
}

/// Given a loop, return nested (inner) loops with multiple non-uniform exits.
/// E.g. assume L2, L3, L5, L7 are only loops with multiple non-uniform exists
/// L1
///    L2
///       L3
///    L4
///       L5
///          L6
///             L7
/// then it returns {L2, L5}
static void getNestedLoopsWithMultpleExists(Loop* L, WIAnalysis* WI,
    SmallVectorImpl<Loop*>& Result) {
    if (getNumOfNonUniformExits(L, WI) > 1) {
        for (auto InnerL : L->getSubLoops()) {
            if (hasMultipleExits(InnerL, WI)) {
                Result.push_back(L);
                return;
            }
        }
        // Only a single level, do not add into the result.
        return;
    }

    // Outer loop is normal. Check its inner loop structure, recursively.
    for (auto InnerL : L->getSubLoops())
        getNestedLoopsWithMultpleExists(InnerL, WI, Result);
}

static const float NestedLoopsWithMultipleExits_THRESHOLD = 0.7f;

/// Return the ratio between loops with multiple exists to other instructions in function.
static float NestedLoopsWithMultipleExitsRatio(Function* F, LoopInfo* LI,
    WIAnalysis* WI) {
    // Find top level nested loops with multiple non-uniform exists.
    SmallVector<Loop*, 8> Loops;
    for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) {
        Loop* L = *I;
        getNestedLoopsWithMultpleExists(L, WI, Loops);
    }

    // Sum the IR size of these loops.
    unsigned LoopSize = 0;
    for (auto L : Loops)
        for (auto BB : L->getBlocks())
            LoopSize += (unsigned)BB->size();

    // Check the ratio between nested loops with multiple exists and the total
    // number of instructions. A higher ratio means these loops dominate this
    // kernel.
    unsigned FuncSize = 0;
    for (auto& BB : *F)
        FuncSize += (unsigned)BB.size();

    if (FuncSize > 0)
    {
        return float(LoopSize) / FuncSize;
    }
    else
    {
        return 0.0f;
    }
}

static const unsigned LongStridedLdStInLoop_THRESHOLD = 3;

typedef struct _LdStInLoop {
  unsigned LDs = 0;
  unsigned STs = 0;
  llvm::Loop* pProblematicLoop = nullptr;
} LdStInLoop;

static const LdStInLoop LongStridedLdStInLoop(Function* F, LoopInfo* LI, WIAnalysis* WI) {
    LdStInLoop retVal;
    SmallVector<Loop*, 32> Loops;
    // Collect innermost simple loop.
    for (auto I = LI->begin(), E = LI->end(); I != E; ++I) {
        auto L = *I;
        if (!IGCLLVM::isInnermost(L))
            continue;
        if (L->getNumBlocks() != 2)
            continue;
        auto* Latch = L->getLoopLatch();
        if (!Latch || !Latch->front().isTerminator())
            continue;
        Loops.push_back(L);
    }
    unsigned LDs = 0;
    unsigned STs = 0;
    for (auto L : Loops) {
        auto BB = L->getHeader();
        for (auto I = BB->begin(), E = BB->end(); I != E; ++I) {
            if (auto LD = dyn_cast<LoadInst>(&*I)) {
                VectorType* VTy = dyn_cast<VectorType>(LD->getType());
                if (!VTy || IGCLLVM::GetVectorTypeBitWidth(VTy) <= 128)
                    continue;
                if (WI->isUniform(LD))
                    continue;
                ++LDs;
            }
            if (auto ST = dyn_cast<StoreInst>(&*I)) {
                Value* Ptr = ST->getPointerOperand();
                Value* Val = ST->getValueOperand();
                VectorType* VTy = dyn_cast<VectorType>(Val->getType());
                if (!VTy || IGCLLVM::GetVectorTypeBitWidth(VTy) <= 128)
                    continue;
                if (WI->isUniform(Ptr))
                    continue;
                ++STs;
            }
        }
        if (LDs > LongStridedLdStInLoop_THRESHOLD ||
            STs > LongStridedLdStInLoop_THRESHOLD)
        {
            retVal.LDs = LDs;
            retVal.STs = STs;
            retVal.pProblematicLoop = L;
            return retVal;
        }
    }
    return retVal;
}

bool Simd32ProfitabilityAnalysis::checkSimd16Profitable(CodeGenContext* ctx) {
    if ((IGC_GET_FLAG_VALUE(OCLSIMD16SelectionMask) & 0x1))
    {
        int loopCyclomaticComplexity = getLoopCyclomaticComplexity();

        ctx->metrics.CollectLoopCyclomaticComplexity(
            F,
            loopCyclomaticComplexity,
            CYCLOMATIC_COMPLEXITY_THRESHOLD);

        if (loopCyclomaticComplexity >= CYCLOMATIC_COMPLEXITY_THRESHOLD)
        {
            return false;
        }
    }

    if (IGC_GET_FLAG_VALUE(OCLSIMD16SelectionMask) & 0x2)
    {
        float nestedLoopsWithMultipleExits = NestedLoopsWithMultipleExitsRatio(F, LI, WI);

        ctx->metrics.CollectNestedLoopsWithMultipleExits(
            F,
            nestedLoopsWithMultipleExits,
            NestedLoopsWithMultipleExits_THRESHOLD);

        if (nestedLoopsWithMultipleExits >= NestedLoopsWithMultipleExits_THRESHOLD)
        {
            return false;
        }
    }

    // If there's wider vector load/store in a loop, skip SIMD16.
    if (IGC_GET_FLAG_VALUE(OCLSIMD16SelectionMask) & 0x4)
    {
        LdStInLoop ldStInLoop = LongStridedLdStInLoop(F, LI, WI);

        ctx->metrics.CollectLongStridedLdStInLoop(
            F,
            ldStInLoop.pProblematicLoop,
            ldStInLoop.LDs,
            ldStInLoop.STs,
            LongStridedLdStInLoop_THRESHOLD);

        if (ldStInLoop.pProblematicLoop != nullptr)
        {
            return false;
        }
    }

    auto hasDouble = [](Function& F) {
        for (auto& BB : F)
            for (auto& I : BB) {
                if (I.getType()->isDoubleTy())
                    return true;
                for (Value* V : I.operands())
                    if (V->getType()->isDoubleTy())
                        return true;
            }
        return false;
    };

    const CPlatform* platform = &ctx->platform;
    if (platform->GetPlatformFamily() == IGFX_GEN9_CORE &&
        platform->getPlatformInfo().eProductFamily == IGFX_GEMINILAKE &&
        hasDouble(*F))
    {
        ctx->metrics.CollectIsGeminiLakeWithDoubles(F, false);
        return false;
    }
    else
    {
        ctx->metrics.CollectIsGeminiLakeWithDoubles(F, true);
    }

    return true;
}

bool Simd32ProfitabilityAnalysis::checkPSSimd32Profitable()
{
    unsigned int numberInstructions = 0;
    unsigned int numberOfHalfInstructions = 0;
    unsigned int numberOfCmp = 0;
    unsigned int numberOfSample = 0;
    unsigned int numberOfBB = 0;
    BasicBlock* returnBlock = nullptr;
    bool hasDiscard = F->getParent()->getNamedMetadata("KillPixel") != nullptr;
    for (Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI)
    {
        for (auto II = FI->begin(), IE = FI->end(); II != IE; ++II)
        {
            if (II->getType() == Type::getHalfTy(F->getContext()))
            {
                numberOfHalfInstructions++;
            }
            if (isa<CmpInst>(*II))
            {
                numberOfCmp++;
            }
            if (isSampleLoadGather4InfoInstruction(&(*II)))
            {
                numberOfSample++;
            }
            numberInstructions++;
        }
        if (isa<ReturnInst>(FI->getTerminator()))
        {
            returnBlock = &(*FI);
        }
        numberOfBB++;
    }
    if (numberInstructions > 4000 || numberInstructions == 0)
    {
        return false;
    }

    // Original SIMD32 heurtistic
    // if 1BB, short, has sample, no discard, no cmp, enable SIMD32
    // skip cmp to avoid flag spill
    if (!hasDiscard && numberOfCmp == 0 && numberOfSample > 0 && numberOfBB == 1 && numberInstructions < 80)
    {
        return true;
    }

    // disable SIMD32 for shader with multiple render target as it puts pressure on the render cache
    unsigned int numberRTWrite = 0;
    for (auto it = returnBlock->begin(), ie = returnBlock->end(); it != ie; ++it)
    {
        if (GenIntrinsicInst * intr = dyn_cast<GenIntrinsicInst>(it))
        {
            if (llvm::isa<llvm::RTWriteIntrinsic>(intr))
            {
                numberRTWrite++;
            }
        }
    }
    if (numberRTWrite > 1)
    {
        return false;
    }

    // Case where we expect to be bound by pixel dispatch time. For small shaderd without IO
    // It is better to go with SIMD32
    if (returnBlock == &F->getEntryBlock() && !hasDiscard)
    {
        bool hasIO = false;
        unsigned int numberInstructions = returnBlock->size();
        if (numberInstructions < 10)
        {
            for (auto II = returnBlock->begin(), IE = returnBlock->end(); II != IE; ++II)
            {
                if (II->mayReadOrWriteMemory() && !isa<RTWriteIntrinsic>(II))
                {
                    hasIO = true;
                    break;
                }
                if (isa<SampleIntrinsic>(II) ||
                    isa<SamplerLoadIntrinsic>(II) ||
                    isa<InfoIntrinsic>(II) ||
                    isa<SamplerGatherIntrinsic>(II))
                {
                    hasIO = true;
                    break;
                }
            }
            if (!hasIO)
            {
                // for small program without IO using SIMD32 allows hiding the thread dispatch time
                return true;
            }
        }
    }

    if (IGC_IS_FLAG_ENABLED(PSSIMD32HeuristicFP16))
    {
        // If we have a large ratio of half use SIMD32 to hide latency better
        float ratioHalf = (float)numberOfHalfInstructions / (float)numberInstructions;
        if (ratioHalf >= 0.5f)
        {
            return true;
        }
    }

    if (IGC_IS_FLAG_ENABLED(PSSIMD32HeuristicLoopAndDiscard))
    {
        // If we have a discard and the first block is small we may be bound by PSD so we try to enable SIMD32
        if (hasDiscard)
        {
            BasicBlock& entryBB = F->getEntryBlock();
            if (!isa<ReturnInst>(entryBB.getTerminator()) && entryBB.size() < 50)
            {
                return true;
            }
        }

        // If we have a loop with high latency enable SIMD32 to reduce latency
        unsigned int numberOfInstructions = 0;
        unsigned int numberOfHighLatencyInst = 0;
        for (LoopInfo::iterator li = LI->begin(), le = LI->end(); li != le; ++li)
        {
            llvm::Loop* loop = *li;
            for (auto BI = loop->block_begin(), BE = loop->block_end(); BI != BE; ++BI)
            {
                for (auto II = (*BI)->begin(), IE = (*BI)->end(); II != IE; ++II)
                {
                    if (isa<SampleIntrinsic>(II))
                    {
                        numberOfHighLatencyInst++;
                    }
                    numberOfInstructions++;
                }
            }
        }
        if (numberOfInstructions < 85 && numberOfHighLatencyInst >= 1)
        {
            // high latency small loop
            return true;
        }
    }
    return false;
}
