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

Copyright (c) 2017 Intel Corporation

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"Software"), to deal in the Software without restriction, including
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======================= end_copyright_notice ==================================*/

#include "Compiler/GenTTI.h"
#include "GenISAIntrinsics/GenIntrinsics.h"
#include "GenISAIntrinsics/GenIntrinsicInst.h"
#include "Compiler/CodeGenPublic.h"
#include "Compiler/IGCPassSupport.h"
#include "Compiler/WaveIntrinsicWAPass.h"
#include "Compiler/CISACodeGen/ShaderCodeGen.hpp"

#include "common/LLVMWarningsPush.hpp"

#include "WrapperLLVM/Utils.h"

#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Support/raw_ostream.h"
#include "common/LLVMWarningsPop.hpp"

using namespace llvm;
using namespace IGC;


namespace llvm {

char DummyPass::ID = 0;
void initializeDummyPassPass(PassRegistry &Registry);
DummyPass::DummyPass() : ImmutablePass(ID) {
    initializeDummyPassPass(*PassRegistry::getPassRegistry());
}

bool GenIntrinsicsTTIImpl::isLoweredToCall(const Function *F)
{
    if (GenISAIntrinsic::isIntrinsic(F))
        return false;
    return BaseT::isLoweredToCall(F);
}

// CFG simplification may produce illegal integer types while simplifying switch
// instructions. Set this to false unless IGC legalization can fix them.
bool GenIntrinsicsTTIImpl::shouldBuildLookupTables()
{
    return false;
}

void *GenIntrinsicsTTIImpl::getAdjustedAnalysisPointer(const void *ID)
{
    if (ID == &TargetTransformInfoWrapperPass::ID)
        return (TargetTransformInfo*)this;
    return this;
}


bool isSendMessage(GenIntrinsicInst *inst)
{
    if (isa<SamplerLoadIntrinsic>(inst) || 
        isa<SampleIntrinsic>(inst) || 
        isa<LdRawIntrinsic>(inst) || 
        isa<InfoIntrinsic>(inst) || 
        isa<SamplerGatherIntrinsic>(inst))
    {
        return true;
    }

    GenISAIntrinsic::ID ID = inst->getIntrinsicID();
    if (/*ID == llvm::GenISAIntrinsic::GenISA_typedwrite ||
        ID == llvm::GenISAIntrinsic::GenISA_typedread ||*/
        ID == llvm::GenISAIntrinsic::GenISA_URBRead ||
        isURBWriteIntrinsic(inst) ||
        ID == llvm::GenISAIntrinsic::GenISA_ldstructured)
    {
        return true;
    }

    return false;
}

unsigned countTotalInstructions(const Function *F, bool CheckSendMsg = true) {
    unsigned EstimatedInstCnt = 0;
    for (auto BBI = F->getBasicBlockList().begin(); BBI != F->getBasicBlockList().end(); BBI++)
    {
        llvm::BasicBlock *BB = const_cast<llvm::BasicBlock*>(&*BBI);
        for (auto II = BB->begin(); II != BB->end(); II++)
        {
            if (llvm::GenIntrinsicInst* pIntrinsic = llvm::dyn_cast<llvm::GenIntrinsicInst>(II))
            {
                if (CheckSendMsg && isSendMessage(pIntrinsic))
                {
                    EstimatedInstCnt += 4;
                }
            }
            EstimatedInstCnt++;
        }
    }
    return EstimatedInstCnt;
}

void GenIntrinsicsTTIImpl::getUnrollingPreferences(Loop *L, 
#if LLVM_VERSION_MAJOR >= 7
	ScalarEvolution &SE, 
#endif
	TTI::UnrollingPreferences &UP)
{
    unsigned LoopUnrollThreshold = ctx->m_DriverInfo.GetLoopUnrollThreshold();

    // override the LoopUnrollThreshold if the registry key is set
    if (IGC_GET_FLAG_VALUE(SetLoopUnrollThreshold) != 0)
    {
        LoopUnrollThreshold = IGC_GET_FLAG_VALUE(SetLoopUnrollThreshold);
    }
    unsigned totalInstCountInShader = countTotalInstructions(L->getBlocks()[0]->getParent());
    bool lowPressure = (this->ctx->m_tempCount < 64) && (totalInstCountInShader<LoopUnrollThreshold);
    // For OCL shaders, do a two-step loop unrolling. The first
    // unrolling is simple and full, and the second runs after
    // LICM, which allows partial unrolling. Same for other APIs?
    if (lowPressure || (ctx->type == ShaderType::OPENCL_SHADER))
    {
        UP.Threshold = LoopUnrollThreshold;
        UP.PartialThreshold = LoopUnrollThreshold;
        UP.Partial = true;
    }
    else  // for high registry pressure shaders, limit the unrolling to small loops and only fully unroll
    {
        UP.Threshold = 200;
    }

#if LLVM_VERSION_MAJOR == 4
	ScalarEvolution *SE = &dummyPass->getAnalysisIfAvailable<ScalarEvolutionWrapperPass>()->getSE();
	if (!SE)
		return;
#endif

    unsigned sendMessage = 0;
    unsigned TripCount = 0;
    BasicBlock *ExitingBlock = L->getLoopLatch();
    if (!ExitingBlock || !L->isLoopExiting(ExitingBlock))
        ExitingBlock = L->getExitingBlock();
     if (ExitingBlock)
         TripCount = IGCLLVM::getref(SE).getSmallConstantTripCount(L, ExitingBlock);

    // Do not enable partial unrolling if the loop counter is float. It can cause precision issue.
    if (ExitingBlock) {
        if (UP.Partial) {
            IGCLLVM::TerminatorInst *Term = ExitingBlock->getTerminator();
            if (BranchInst *BI = dyn_cast<BranchInst>(Term))
            {
                if (dyn_cast<FCmpInst>(BI->getCondition()))
                {
                    UP.Partial = false;
                    return;
                }
            }
        }
        // Add heuristic to disable loop unroll for single short BB loop with
        // barrier. Unrolling such a loop won't remove dependency due to that
        // barrier but only add register pressure potentially.
        if (L->getNumBlocks() == 1) {
            BasicBlock *BB = *L->block_begin();

            SmallPtrSet<const Value *, 32> EphValues;
            CodeMetrics Metrics;
            Metrics.analyzeBasicBlock(BB, *this, EphValues);
            if (Metrics.NumInsts < 50) {
                for (auto I = BB->begin(), E = BB->end(); I != E; ++I) {
                    CallInst *Call = dyn_cast<CallInst>(I);
                    if (!Call)
                        continue;
                    Function *F = Call->getCalledFunction();
                    if (!F)
                        continue;
                    // FIXME: Shall we already inline barrier even in two-phase
                    // inlining?
                    if (F->getName() == "_Z7barrierj") {
                        // Disable loop unrolling for short loop with
                        // barrier, where we prefer wider SIMD to mitigate
                        // the barrier overhead.
                        UP.Count = 1;
                        UP.MaxCount = UP.Count;
                        UP.Partial = false;
                        UP.Runtime = false;
                        return;
                    }
                }
            }
        }
    }

    // Skip non-simple loop.
    if (L->getNumBlocks() != 1) {
        if (IGC_IS_FLAG_ENABLED(EnableAdvRuntimeUnroll) && L->empty()) {
          auto countNonPHI = [](BasicBlock *BB) {
            unsigned Total = BB->size();
            unsigned PHIs = 0;
            for (auto BI = BB->begin(), BE = BB->end(); BI != BE; ++BI) {
              if (!isa<PHINode>(&*BI))
                break;
              ++PHIs;
            }
            return Total - PHIs;
          };
          auto hasLoad = [](BasicBlock *BB) {
            for (auto BI = BB->begin(), BE = BB->end(); BI != BE; ++BI)
              if (isa<LoadInst>(&*BI))
                return true;
            return false;
          };
          auto hasStore = [](BasicBlock *BB) {
            for (auto BI = BB->begin(), BE = BB->end(); BI != BE; ++BI)
              if (isa<StoreInst>(&*BI))
                return true;
            return false;
          };
          auto hasCall = [](BasicBlock *BB) {
            for (auto BI = BB->begin(), BE = BB->end(); BI != BE; ++BI)
              if (isa<CallInst>(&*BI) &&
                  !isa<IntrinsicInst>(&*BI) && !isa<GenIntrinsicInst>(&*BI))
                return true;
            return false;
          };
          // For innermost loop, allow certain patterns.
          unsigned Count = 0;
          bool HasCall = false;
          bool HasStore = false;
          bool MayHasLoadInHeaderOnly = true;
          for (auto BI = L->block_begin(), BE = L->block_end(); BI != BE; ++BI) {
            Count += countNonPHI(*BI);
            HasCall |= hasCall(*BI);
            HasStore |= hasStore(*BI);
            if (L->getHeader() != *BI)
              MayHasLoadInHeaderOnly &= !hasLoad(*BI);
          }
          // Runtime unroll it.
          if (!HasCall && !HasStore && MayHasLoadInHeaderOnly && Count < 100) {
            unsigned C = IGC_GET_FLAG_VALUE(AdvRuntimeUnrollCount);
            if (C == 0) C = 4;
            UP.Runtime = true;
            UP.Count = C;
            UP.MaxCount = UP.Count;
            // The following is only available and required from LLVM 3.7+.
            UP.AllowExpensiveTripCount = true;
          }
        }
        return;
    }

    llvm::BasicBlock::InstListType::iterator I;
    llvm::BasicBlock::InstListType &instructionList = L->getBlocks()[0]->getInstList();
    int instCount = instructionList.size();

    // Check if the specific basic block has block read or write.
    auto hasBlockReadWrite = [] (BasicBlock *BB) -> bool {
      for (auto I = BB->begin(), E = BB->end(); I != E; ++I)
        if (auto GII = dyn_cast<GenIntrinsicInst>(I))
          switch (GII->getIntrinsicID()) {
          case GenISAIntrinsic::GenISA_simdBlockRead:
          case GenISAIntrinsic::GenISA_simdBlockWrite:
            return true;
          default:
            break;
          }
      return false;
    };
    // Skip the following logic for OCL. Apparently, it's designed to prevent
    // loops in 3D shaders being aggressively unrolled to increase shader
    // binary size dramatically. So far, OCL doesn't have such concern and, if
    // we need to consider that, more factors need consideration. Just skip
    // that for OCL.
    if (ctx->type == ShaderType::OPENCL_SHADER &&
        // Only try to fully unroll small loop with known but small trip count.
        // This's PURELY heuristics.
        ((TripCount != 0 && TripCount <= 40 && instCount < 40) ||
         hasBlockReadWrite(L->getHeader())) &&
        // FIXME: WA for cases where the compiler is running with a smaller stack size
        // we run into stack overflow in 
        !ctx->m_DriverInfo.HasSmallStack())
    {
        return;
    }

    for (I = instructionList.begin(); I != instructionList.end(); I++)
    {
        if (llvm::GenIntrinsicInst* pIntrinsic = llvm::dyn_cast<llvm::GenIntrinsicInst>(I))
        {
            if (isSendMessage(pIntrinsic))
            {
                sendMessage++;
            }
        }
    }

    int estimateUnrolledInstCount = (instCount + sendMessage * 4) * TripCount;
    int unrollLimitInstCount = MAX(LoopUnrollThreshold - totalInstCountInShader, 0);
    
    // if the loop doesn't have sample, skip the unrolling parameter change
    if (!sendMessage)
    {
        // if the estimated unrolled instruction count is larger than the unrolling threshold, limit unrolling.
        if (estimateUnrolledInstCount > unrollLimitInstCount)
        {
            UP.Count = MIN(unrollLimitInstCount / (instCount + sendMessage * 4), 4);
            if (TripCount != 0)
                while (UP.Count != 0 && TripCount % UP.Count != 0)
                    UP.Count--;
            UP.MaxCount = UP.Count;
        }
        return;
    }

    // if the TripCount is known, and the estimated unrolled count exceed LoopUnrollThreshold, set the unrolling count to 4
    if (estimateUnrolledInstCount > unrollLimitInstCount)
    {
        UP.Count = MIN(TripCount, 4);
        UP.MaxCount = UP.Count;
    }

    // do not enable runtime unrolling if the loop is long or trip count is already known.
    if (instCount>35 || TripCount)
    {
        return;
    }
    
    if (IGC_IS_FLAG_ENABLED(DisableRuntimeLoopUnrolling))
    {
        return;
    }

    UP.Runtime = true;
    UP.Count = 4;
    UP.MaxCount = UP.Count;
    // The following is only available and required from LLVM 3.7+.
    UP.AllowExpensiveTripCount = true;

    if (MDNode *LoopID = L->getLoopID())
    {
        const llvm::StringRef maxIterMetadataNames = "spv.loop.iterations.max";
        const llvm::StringRef peelCountMetadataNames = "spv.loop.peel.count";

        for (unsigned i = 0; i < LoopID->getNumOperands(); ++i)
        {
            if (MDNode *MD = llvm::dyn_cast<MDNode>(LoopID->getOperand(i)))
            {
                if (MDString *S = llvm::dyn_cast<MDString>(MD->getOperand(0)))
                {
                    if (maxIterMetadataNames.equals(S->getString()))
                    {
                        UP.MaxCount = static_cast<unsigned>(
                            mdconst::extract<ConstantInt>(MD->getOperand(1))->getZExtValue());
                    }
                    else if (peelCountMetadataNames.equals(S->getString()))
                    {
                        UP.AllowPeeling = true;
                        UP.PeelCount = static_cast<unsigned>(
                            mdconst::extract<ConstantInt>(MD->getOperand(1))->getZExtValue());
                    }
                }
            }
        }
    }
}


bool GenIntrinsicsTTIImpl::isProfitableToHoist(Instruction *I)
{
    if (auto *CI = dyn_cast<CallInst>(I))
    {
        if (unsafeToHoist(CI))
            return false;
    }
    return BaseT::isProfitableToHoist(I);
}

unsigned GenIntrinsicsTTIImpl::getCallCost(const Function *F, ArrayRef<const Value *> Arguments) {
    IGC::CodeGenContext *CGC = this->ctx;
    if (!CGC->enableFunctionCall() && !GenISAIntrinsic::isIntrinsic(F) &&
        !F->isIntrinsic()) {
        // If subroutine call is not enabled but we have function call. They
        // are not inlined. e.g. due to two-phase inlining. Return function
        // size instead of to avoid under-estimating the cost of function call.
        //
        // FIXME: We need to collect the cost following calling graph. However,
        // as LLVM's ininer only support bottom-up inlining currently. That's
        // not a big issue so far.
        // 
        // FIXME: We also need to consider the case where sub-routine call is
        // enabled.
        unsigned FuncSize = countTotalInstructions(F, false);
        return TargetTransformInfo::TCC_Basic * FuncSize;
    }
    return BaseT::getCallCost(F, Arguments);
}

} // namespace llvm
// Register the basic pass.
INITIALIZE_PASS(DummyPass, "gen-tti-dummy-pass",
    "Dummy Pass for GenTTIImpl", false, true)
