DirectXShaderCompiler/lib/HLSL/ComputeViewIdState.cpp

///////////////////////////////////////////////////////////////////////////////
//                                                                           //
// ViewIdAnalysis.cpp                                                        //
// Copyright (C) Microsoft Corporation. All rights reserved.                 //
// This file is distributed under the University of Illinois Open Source     //
// License. See LICENSE.TXT for details.                                     //
//                                                                           //
///////////////////////////////////////////////////////////////////////////////

#include "dxc/HLSL/ComputeViewIdState.h"
#include "dxc/Support/Global.h"
#include "dxc/HLSL/DxilModule.h"
#include "dxc/HLSL/DxilOperations.h"
#include "dxc/HLSL/DxilInstructions.h"

#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Operator.h"
#include "llvm/Pass.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/Support/Debug.h"
#include "llvm/IR/CFG.h"
#include "llvm/Analysis/CallGraph.h"

#include <algorithm>

using namespace llvm;
using namespace llvm::legacy;
using namespace hlsl;
using llvm::legacy::PassManager;
using llvm::legacy::FunctionPassManager;
using std::vector;
using std::unordered_set;
using std::unordered_map;

#define DXILVIEWID_DBG   0

#define DEBUG_TYPE "viewid"


DxilViewIdState::DxilViewIdState(DxilModule *pDxilModule) : m_pModule(pDxilModule) {}
unsigned DxilViewIdState::getNumInputSigScalars() const                   { return m_NumInputSigScalars; }
unsigned DxilViewIdState::getNumOutputSigScalars(unsigned StreamId) const { return m_NumOutputSigScalars[StreamId]; }
unsigned DxilViewIdState::getNumPCSigScalars() const                      { return m_NumPCSigScalars; }
const DxilViewIdState::OutputsDependentOnViewIdType   &DxilViewIdState::getOutputsDependentOnViewId(unsigned StreamId) const    { return m_OutputsDependentOnViewId[StreamId]; }
const DxilViewIdState::OutputsDependentOnViewIdType   &DxilViewIdState::getPCOutputsDependentOnViewId() const                   { return m_PCOutputsDependentOnViewId; }
const DxilViewIdState::InputsContributingToOutputType &DxilViewIdState::getInputsContributingToOutputs(unsigned StreamId) const { return m_InputsContributingToOutputs[StreamId]; }
const DxilViewIdState::InputsContributingToOutputType &DxilViewIdState::getInputsContributingToPCOutputs() const                { return m_InputsContributingToPCOutputs; }
const DxilViewIdState::InputsContributingToOutputType &DxilViewIdState::getPCInputsContributingToOutputs() const                { return m_PCInputsContributingToOutputs; }

void DxilViewIdState::Compute() {
  Clear();

  const ShaderModel *pSM = m_pModule->GetShaderModel();
  m_bUsesViewId = m_pModule->m_ShaderFlags.GetViewID();

  // 1. Traverse signature MD to determine max packed location.
  DetermineMaxPackedLocation(m_pModule->GetInputSignature(), &m_NumInputSigScalars, 1);
  DetermineMaxPackedLocation(m_pModule->GetOutputSignature(), &m_NumOutputSigScalars[0], pSM->IsGS() ? kNumStreams : 1);
  DetermineMaxPackedLocation(m_pModule->GetPatchConstantSignature(), &m_NumPCSigScalars, 1);

  // 2. Collect sets of functions reachable from main and pc entries.
  CallGraphAnalysis CGA;
  CallGraph CG = CGA.run(m_pModule->GetModule());
  m_Entry.pEntryFunc = m_pModule->GetEntryFunction();
  m_PCEntry.pEntryFunc = m_pModule->GetPatchConstantFunction();
  ComputeReachableFunctionsRec(CG, CG[m_Entry.pEntryFunc], m_Entry.Functions);
  if (m_PCEntry.pEntryFunc) {
    DXASSERT_NOMSG(pSM->IsHS());
    ComputeReachableFunctionsRec(CG, CG[m_PCEntry.pEntryFunc], m_PCEntry.Functions);
  }

  // 3. Determine shape components that are dynamically accesses and collect all sig outputs.
  AnalyzeFunctions(m_Entry);
  if (m_PCEntry.pEntryFunc) {
    AnalyzeFunctions(m_PCEntry);
  }

  // 4. Collect sets of values contributing to outputs.
  CollectValuesContributingToOutputs(m_Entry);
  if (m_PCEntry.pEntryFunc) {
    CollectValuesContributingToOutputs(m_PCEntry);
  }

  // 5. Construct dependency sets.
  for (unsigned StreamId = 0; StreamId < (pSM->IsGS() ? kNumStreams : 1u); StreamId++) {
    CreateViewIdSets(m_Entry.ContributingInstructions[StreamId],
                     m_OutputsDependentOnViewId[StreamId],
                     m_InputsContributingToOutputs[StreamId], false);
  }
  if (pSM->IsHS()) {
    CreateViewIdSets(m_PCEntry.ContributingInstructions[0],
                     m_PCOutputsDependentOnViewId,
                     m_InputsContributingToPCOutputs, true);
  } else if (pSM->IsDS()) {
    OutputsDependentOnViewIdType OutputsDependentOnViewId;
    CreateViewIdSets(m_Entry.ContributingInstructions[0],
                     OutputsDependentOnViewId,
                     m_PCInputsContributingToOutputs, true);
    DXASSERT_NOMSG(OutputsDependentOnViewId == m_OutputsDependentOnViewId[0]);
  }

  // 6. Update dynamically indexed input/output component masks.
  UpdateDynamicIndexUsageState();

#if DXILVIEWID_DBG
  PrintSets(dbgs());
#endif
}

void DxilViewIdState::PrintSets(llvm::raw_ostream &OS) {
  const ShaderModel *pSM = m_pModule->GetShaderModel();
  OS << "ViewId state: \n";

  if (!pSM->IsGS()) {
    OS << "Number of inputs: " << m_NumInputSigScalars     << 
                 ", outputs: " << m_NumOutputSigScalars[0] << 
              ", patchconst: " << m_NumPCSigScalars        << "\n";
  } else {
    OS << "Number of inputs: "   << m_NumInputSigScalars     << 
                 ", outputs: { " << m_NumOutputSigScalars[0] << ", " << m_NumOutputSigScalars[1] << ", " <<
                                    m_NumOutputSigScalars[2] << ", " << m_NumOutputSigScalars[3] << " }" <<
              ", patchconst: "   << m_NumPCSigScalars        << "\n";
  }

  if (!pSM->IsGS()) {
    PrintOutputsDependentOnViewId(OS, "Outputs", m_NumOutputSigScalars[0], m_OutputsDependentOnViewId[0]);
  } else {
    PrintOutputsDependentOnViewId(OS, "Outputs for Stream0", m_NumOutputSigScalars[0], m_OutputsDependentOnViewId[0]);
    PrintOutputsDependentOnViewId(OS, "Outputs for Stream1", m_NumOutputSigScalars[1], m_OutputsDependentOnViewId[1]);
    PrintOutputsDependentOnViewId(OS, "Outputs for Stream2", m_NumOutputSigScalars[2], m_OutputsDependentOnViewId[2]);
    PrintOutputsDependentOnViewId(OS, "Outputs for Stream3", m_NumOutputSigScalars[3], m_OutputsDependentOnViewId[3]);
  }
  if (pSM->IsHS()) {
    PrintOutputsDependentOnViewId(OS, "PCOutputs", m_NumPCSigScalars, m_PCOutputsDependentOnViewId);
  }

  if (!pSM->IsGS()) {
    PrintInputsContributingToOutputs(OS, "Inputs", "Outputs", m_InputsContributingToOutputs[0]);
  } else {
    PrintInputsContributingToOutputs(OS, "Inputs", "Outputs for Stream0", m_InputsContributingToOutputs[0]);
    PrintInputsContributingToOutputs(OS, "Inputs", "Outputs for Stream1", m_InputsContributingToOutputs[1]);
    PrintInputsContributingToOutputs(OS, "Inputs", "Outputs for Stream2", m_InputsContributingToOutputs[2]);
    PrintInputsContributingToOutputs(OS, "Inputs", "Outputs for Stream3", m_InputsContributingToOutputs[3]);
  }
  if (pSM->IsHS()) {
    PrintInputsContributingToOutputs(OS, "Inputs", "PCOutputs", m_InputsContributingToPCOutputs);
  } else if (pSM->IsDS()) {
    PrintInputsContributingToOutputs(OS, "PCInputs", "Outputs", m_PCInputsContributingToOutputs);
  }
  OS << "\n";
}

void DxilViewIdState::PrintOutputsDependentOnViewId(llvm::raw_ostream &OS,
                                                    llvm::StringRef SetName,
                                                    unsigned NumOutputs,
                                                    const OutputsDependentOnViewIdType &OutputsDependentOnViewId) {
  OS << SetName << " dependent on ViewId: { ";
  bool bFirst = true;
  for (unsigned i = 0; i < NumOutputs; i++) {
    if (OutputsDependentOnViewId[i]) {
      if (!bFirst) OS << ", ";
      OS << i;
      bFirst = false;
    }
  }
  OS << " }\n";
}

void DxilViewIdState::PrintInputsContributingToOutputs(llvm::raw_ostream &OS,
                                                       llvm::StringRef InputSetName,
                                                       llvm::StringRef OutputSetName,
                                                       const InputsContributingToOutputType &InputsContributingToOutputs) {
  OS << InputSetName << " contributing to computation of " << OutputSetName << ":\n";
  for (auto &it : InputsContributingToOutputs) {
    unsigned outIdx = it.first;
    auto &Inputs = it.second;
    OS << "output " << outIdx << " depends on inputs: { ";
    bool bFirst = true;
    for (unsigned i : Inputs) {
      if (!bFirst) OS << ", ";
      OS << i;
      bFirst = false;
    }
    OS << " }\n";
  }
}

void DxilViewIdState::Clear() {
  m_bUsesViewId = false;
  m_NumInputSigScalars  = 0;
  for (unsigned i = 0; i < kNumStreams; i++) {
    m_NumOutputSigScalars[i] = 0;
    m_OutputsDependentOnViewId[i].reset();
    m_InputsContributingToOutputs[i].clear();
  }
  m_NumPCSigScalars     = 0;
  m_InpSigDynIdxElems.clear();
  m_OutSigDynIdxElems.clear();
  m_PCSigDynIdxElems.clear();
  m_PCOutputsDependentOnViewId.reset();
  m_InputsContributingToPCOutputs.clear();
  m_PCInputsContributingToOutputs.clear();
  m_Entry.Clear();
  m_PCEntry.Clear();
  m_FuncInfo.clear();
  m_ReachingDeclsCache.clear();
  m_SerializedState.clear();
}

void DxilViewIdState::EntryInfo::Clear() {
  pEntryFunc = nullptr;
  Functions.clear();
  Outputs.clear();
  for (unsigned i = 0; i < kNumStreams; i++)
    ContributingInstructions[i].clear();
}

void DxilViewIdState::FuncInfo::Clear() {
  Returns.clear();
  CtrlDep.Clear();
  pDomTree.reset();
}

void DxilViewIdState::DetermineMaxPackedLocation(DxilSignature &DxilSig,
                                                 unsigned *pMaxSigLoc,
                                                 unsigned NumStreams) {
  if (&DxilSig == nullptr) return;
  DXASSERT_NOMSG(NumStreams == 1 || NumStreams == kNumStreams);

  for (unsigned i = 0; i < NumStreams; i++) {
    pMaxSigLoc[i] = 0;
  }

  for (auto &E : DxilSig.GetElements()) {
    if (E->GetStartRow() == Semantic::kUndefinedRow) continue;

    unsigned StreamId = E->GetOutputStream();
    unsigned endLoc = GetLinearIndex(*E, E->GetRows() - 1, E->GetCols() - 1);
    pMaxSigLoc[StreamId] = std::max(pMaxSigLoc[StreamId], endLoc + 1);
    E->GetCols();
  }
}

void DxilViewIdState::ComputeReachableFunctionsRec(CallGraph &CG, CallGraphNode *pNode, FunctionSetType &FuncSet) {
  Function *F = pNode->getFunction();
  // Accumulate only functions with bodies.
  if (F->empty()) return;
  auto itIns = FuncSet.emplace(F);
  DXASSERT_NOMSG(itIns.second);
  for (auto it = pNode->begin(), itEnd = pNode->end(); it != itEnd; ++it) {
    CallGraphNode *pSuccNode = it->second;
    ComputeReachableFunctionsRec(CG, pSuccNode, FuncSet);
  }
}

static bool GetUnsignedVal(Value *V, uint32_t *pValue) {
  ConstantInt *CI = dyn_cast<ConstantInt>(V);
  if (!CI) return false;
  uint64_t u = CI->getZExtValue();
  if (u > UINT32_MAX) return false;
  *pValue = (uint32_t)u;
  return true;
}

void DxilViewIdState::AnalyzeFunctions(EntryInfo &Entry) {
  for (auto *F : Entry.Functions) {
    DXASSERT_NOMSG(!F->empty());

    auto itFI = m_FuncInfo.find(F);
    FuncInfo *pFuncInfo = nullptr;
    if (itFI != m_FuncInfo.end()) {
      pFuncInfo = itFI->second.get();
    } else {
      m_FuncInfo[F] = make_unique<FuncInfo>();
      pFuncInfo = m_FuncInfo[F].get();
    }

    for (auto itBB = F->begin(), endBB = F->end(); itBB != endBB; ++itBB) {
      BasicBlock *BB = itBB;

      for (auto itInst = BB->begin(), endInst = BB->end(); itInst != endInst; ++itInst) {
        if (ReturnInst *RI = dyn_cast<ReturnInst>(itInst)) {
          pFuncInfo->Returns.emplace(RI);
          continue;
        }

        CallInst *CI = dyn_cast<CallInst>(itInst);
        if (!CI) continue;

        DynamicallyIndexedElemsType *pDynIdxElems = nullptr;
        int row = Semantic::kUndefinedRow;
        unsigned id, col;
        if (DxilInst_LoadInput LI = DxilInst_LoadInput(CI)) {
          pDynIdxElems = &m_InpSigDynIdxElems;
          IFTBOOL(GetUnsignedVal(LI.get_inputSigId(), &id), DXC_E_GENERAL_INTERNAL_ERROR);
          GetUnsignedVal(LI.get_rowIndex(), (uint32_t*)&row);
          IFTBOOL(GetUnsignedVal(LI.get_colIndex(), &col), DXC_E_GENERAL_INTERNAL_ERROR);
        } else if (DxilInst_StoreOutput SO = DxilInst_StoreOutput(CI)) {
          pDynIdxElems = &m_OutSigDynIdxElems;
          IFTBOOL(GetUnsignedVal(SO.get_outputSigId(), &id), DXC_E_GENERAL_INTERNAL_ERROR);
          GetUnsignedVal(SO.get_rowIndex(), (uint32_t*)&row);
          IFTBOOL(GetUnsignedVal(SO.get_colIndex(), &col), DXC_E_GENERAL_INTERNAL_ERROR);
          Entry.Outputs.emplace(CI);
        } else if (DxilInst_LoadPatchConstant LPC = DxilInst_LoadPatchConstant(CI)) {
          if (m_pModule->GetShaderModel()->IsDS()) {
            pDynIdxElems = &m_PCSigDynIdxElems;
            IFTBOOL(GetUnsignedVal(LPC.get_inputSigId(), &id), DXC_E_GENERAL_INTERNAL_ERROR);
            GetUnsignedVal(LPC.get_row(), (uint32_t*)&row);
            IFTBOOL(GetUnsignedVal(LPC.get_col(), &col), DXC_E_GENERAL_INTERNAL_ERROR);
          } else {
            // Do nothing. This is an internal helper function for DXBC-2-DXIL converter.
            DXASSERT_NOMSG(m_pModule->GetShaderModel()->IsHS());
          }
        } else if (DxilInst_StorePatchConstant SPC = DxilInst_StorePatchConstant(CI)) {
          pDynIdxElems = &m_PCSigDynIdxElems;
          IFTBOOL(GetUnsignedVal(SPC.get_outputSigID(), &id), DXC_E_GENERAL_INTERNAL_ERROR);
          GetUnsignedVal(SPC.get_row(), (uint32_t*)&row);
          IFTBOOL(GetUnsignedVal(SPC.get_col(), &col), DXC_E_GENERAL_INTERNAL_ERROR);
          Entry.Outputs.emplace(CI);
        } else if (DxilInst_LoadOutputControlPoint LOCP = DxilInst_LoadOutputControlPoint(CI)) {
          if (m_pModule->GetShaderModel()->IsDS()) {
            pDynIdxElems = &m_InpSigDynIdxElems;
            IFTBOOL(GetUnsignedVal(LOCP.get_inputSigId(), &id), DXC_E_GENERAL_INTERNAL_ERROR);
            GetUnsignedVal(LOCP.get_row(), (uint32_t*)&row);
            IFTBOOL(GetUnsignedVal(LOCP.get_col(), &col), DXC_E_GENERAL_INTERNAL_ERROR);
          } else if (m_pModule->GetShaderModel()->IsHS()) {
            // Do nothings, as the information has been captured by the output signature of CP entry.
          } else {
            DXASSERT_NOMSG(false);
          }
        } else {
          continue;
        }

        // Record dynamic index usage.
        if (pDynIdxElems && row == Semantic::kUndefinedRow) {
          (*pDynIdxElems)[id] |= (1 << col);
        }
      }
    }

    // Compute dominator relation.
    pFuncInfo->pDomTree = make_unique<DominatorTreeBase<BasicBlock> >(false);
    pFuncInfo->pDomTree->recalculate(*F);
#if DXILVIEWID_DBG
    pFuncInfo->pDomTree->print(dbgs());
#endif

    // Compute postdominator relation.
    DominatorTreeBase<BasicBlock> PDR(true);
    PDR.recalculate(*F);
#if DXILVIEWID_DBG
    PDR.print(dbgs());
#endif
    // Compute control dependence.
    pFuncInfo->CtrlDep.Compute(F, PDR);
#if DXILVIEWID_DBG
    pFuncInfo->CtrlDep.print(dbgs());
#endif
  }
}

void DxilViewIdState::CollectValuesContributingToOutputs(EntryInfo &Entry) {
  for (auto *CI : Entry.Outputs) {  // CI = call instruction
    DxilSignature *pDxilSig = nullptr;
    Value *pContributingValue = nullptr;
    unsigned id = (unsigned)-1;
    int startRow = Semantic::kUndefinedRow, endRow = Semantic::kUndefinedRow;
    unsigned col = (unsigned)-1;
    if (DxilInst_StoreOutput SO = DxilInst_StoreOutput(CI)) {
      pDxilSig = &m_pModule->GetOutputSignature();
      pContributingValue = SO.get_value();
      GetUnsignedVal(SO.get_outputSigId(), &id);
      GetUnsignedVal(SO.get_colIndex(), &col);
      GetUnsignedVal(SO.get_rowIndex(), (uint32_t*)&startRow);
    } else if (DxilInst_StorePatchConstant SPC = DxilInst_StorePatchConstant(CI)) {
      pDxilSig = &m_pModule->GetPatchConstantSignature();
      pContributingValue = SPC.get_value();
      GetUnsignedVal(SPC.get_outputSigID(), &id);
      GetUnsignedVal(SPC.get_row(), (uint32_t*)&startRow);
      GetUnsignedVal(SPC.get_col(), &col);
    } else {
      IFT(DXC_E_GENERAL_INTERNAL_ERROR);
    }

    DxilSignatureElement &SigElem = pDxilSig->GetElement(id);
    if (!SigElem.IsAllocated())
      continue;

    unsigned StreamId = SigElem.GetOutputStream();

    if (startRow != Semantic::kUndefinedRow) {
      endRow = startRow;
    } else {
      // The entire column is affected by value.
      DXASSERT_NOMSG(SigElem.GetID() == id && SigElem.GetStartRow() != Semantic::kUndefinedRow);
      startRow = 0;
      endRow = SigElem.GetRows() - 1;
    }

    InstructionSetType ContributingInstructionsAllRows;
    InstructionSetType *pContributingInstructions = &ContributingInstructionsAllRows;
    if (startRow == endRow) {
      // Scalar or indexable with known index.
      unsigned index = GetLinearIndex(SigElem, startRow, col);
      pContributingInstructions = &Entry.ContributingInstructions[StreamId][index];
    }

    CollectValuesContributingToOutputRec(Entry, pContributingValue, *pContributingInstructions);

    // Handle control dependence of this instruction BB.
    BasicBlock *pBB = CI->getParent();
    Function *F = pBB->getParent();
    FuncInfo *pFuncInfo = m_FuncInfo[F].get();
    const BasicBlockSet &CtrlDepSet = pFuncInfo->CtrlDep.GetCDBlocks(pBB);
    for (BasicBlock *B : CtrlDepSet) {
      CollectValuesContributingToOutputRec(Entry, B->getTerminator(), *pContributingInstructions);
    }

    if (pContributingInstructions == &ContributingInstructionsAllRows) {
      // Write dynamically indexed output contributions to all rows.
      for (int row = startRow; row <= endRow; row++) {
        unsigned index = GetLinearIndex(SigElem, row, col);
        Entry.ContributingInstructions[StreamId][index].insert(ContributingInstructionsAllRows.begin(), ContributingInstructionsAllRows.end());
      }
    }
  }
}

void DxilViewIdState::CollectValuesContributingToOutputRec(EntryInfo &Entry,
                                                           Value *pContributingValue,
                                                           InstructionSetType &ContributingInstructions) {
  if (Argument *pArg = dyn_cast<Argument>(pContributingValue)) {
    // This must be a leftover signature argument of an entry function.
    DXASSERT_NOMSG(Entry.pEntryFunc == m_pModule->GetEntryFunction() ||
                   Entry.pEntryFunc == m_pModule->GetPatchConstantFunction());
    return;
  }

  Instruction *pContributingInst = dyn_cast<Instruction>(pContributingValue);
  if (pContributingInst == nullptr) {
    // Can be literal constant, global decl, branch target.
    DXASSERT_NOMSG(isa<Constant>(pContributingValue) || isa<BasicBlock>(pContributingValue));
    return;
  }

  auto itInst = ContributingInstructions.emplace(pContributingInst);
  // Already visited instruction.
  if (!itInst.second) return;

  // Handle special cases.
  if (PHINode *phi = dyn_cast<PHINode>(pContributingInst)) {
    CollectPhiCFValuesContributingToOutputRec(phi, Entry, ContributingInstructions);
  } else if (isa<LoadInst>(pContributingInst) || 
             isa<AtomicCmpXchgInst>(pContributingInst) ||
             isa<AtomicRMWInst>(pContributingInst)) {
    Value *pPtrValue = pContributingInst->getOperand(0);
    DXASSERT_NOMSG(pPtrValue->getType()->isPointerTy());
    const ValueSetType &ReachingDecls = CollectReachingDecls(pPtrValue);
    DXASSERT_NOMSG(ReachingDecls.size() > 0);
    for (Value *pDeclValue : ReachingDecls) {
      const ValueSetType &Stores = CollectStores(pDeclValue);
      for (Value *V : Stores) {
        CollectValuesContributingToOutputRec(Entry, V, ContributingInstructions);
      }
    }
  } else if (CallInst *CI = dyn_cast<CallInst>(pContributingInst)) {
    if (!hlsl::OP::IsDxilOpFuncCallInst(CI)) {
      Function *F = CI->getCalledFunction();
      if (!F->empty()) {
        // Return value of a user function.
        if (Entry.Functions.find(F) != Entry.Functions.end()) {
          const FuncInfo &FI = *m_FuncInfo[F];
          for (ReturnInst *pRetInst : FI.Returns) {
            CollectValuesContributingToOutputRec(Entry, pRetInst, ContributingInstructions);
          }
        }
      }
    }
  }

  // Handle instruction inputs.
  unsigned NumOps = pContributingInst->getNumOperands();
  for (unsigned i = 0; i < NumOps; i++) {
    Value *O = pContributingInst->getOperand(i);
    CollectValuesContributingToOutputRec(Entry, O, ContributingInstructions);
  }

  // Handle control dependence of this instruction BB.
  BasicBlock *pBB = pContributingInst->getParent();
  Function *F = pBB->getParent();
  FuncInfo *pFuncInfo = m_FuncInfo[F].get();
  const BasicBlockSet &CtrlDepSet = pFuncInfo->CtrlDep.GetCDBlocks(pBB);
  for (BasicBlock *B : CtrlDepSet) {
    CollectValuesContributingToOutputRec(Entry, B->getTerminator(), ContributingInstructions);
  }
}

// Only process control-dependent basic blocks for constant operands of the phi-function.
// An obvious "definition" point for a constant operand is the predecessor along corresponding edge.
// However, this may be too conservative and, as such, pick up extra control dependent BBs.
// A better "definition" point is the highest dominator where it is still legal to "insert" constant assignment.
// In this context, "legal" means that only one value "leaves" the dominator and reaches Phi.
void DxilViewIdState::CollectPhiCFValuesContributingToOutputRec(PHINode *pPhi,
                                                                EntryInfo &Entry,
                                                                InstructionSetType &ContributingInstructions) {
  Function *F = pPhi->getParent()->getParent();
  FuncInfo *pFuncInfo = m_FuncInfo[F].get();
  unordered_map<DomTreeNodeBase<BasicBlock> *, Value *> DomTreeMarkers;

  // Mark predecessors of each value, so that there is a legal "definition" point.
  for (unsigned i = 0; i < pPhi->getNumOperands(); i++) {
    Value *pValue = pPhi->getIncomingValue(i);
    BasicBlock *pBB = pPhi->getIncomingBlock(i);
    DomTreeNodeBase<BasicBlock> *pDomNode = pFuncInfo->pDomTree->getNode(pBB);
    auto it = DomTreeMarkers.emplace(pDomNode, pValue);
    DXASSERT_NOMSG(it.second || it.first->second == pValue); it;
  }
  // Mark the dominator tree with "definition" values, walking up to the parent.
  for (unsigned i = 0; i < pPhi->getNumOperands(); i++) {
    Value *pValue = pPhi->getIncomingValue(i);
    BasicBlock *pDefBB = &F->getEntryBlock();
    if (Instruction *pDefInst = dyn_cast<Instruction>(pValue)) {
      pDefBB = pDefInst->getParent();
    }

    BasicBlock *pBB = pPhi->getIncomingBlock(i);
    if (pBB == pDefBB) {
      continue; // we already handled the predecessor.
    }
    DomTreeNodeBase<BasicBlock> *pDomNode = pFuncInfo->pDomTree->getNode(pBB);
    pDomNode = pDomNode->getIDom();
    while (pDomNode) {
      auto it = DomTreeMarkers.emplace(pDomNode, pValue);
      if (!it.second) {
        if (it.first->second != pValue && it.first->second != nullptr) {
          if (!isa<Constant>(it.first->second) || !isa<Constant>(pValue)) {
            // Unless both are different constants, mark the "definition" point as illegal.
            it.first->second = nullptr;
            // If both are constants, leave the marker of the first one.
          }
        }
        break;
      }

      // Do not go higher than a legal definition point.
      pBB = pDomNode->getBlock();
      if (pBB == pDefBB)
        break;

      pDomNode = pDomNode->getIDom();
    }
  }

  // Handle control dependence for Constant arguments of Phi.
  for (unsigned i = 0; i < pPhi->getNumOperands(); i++) {
    Value *pValue = pPhi->getIncomingValue(i);
    if (!isa<Constant>(pValue))
      continue;

    // Determine the higher legal "definition" point.
    BasicBlock *pBB = pPhi->getIncomingBlock(i);
    DomTreeNodeBase<BasicBlock> *pDomNode = pFuncInfo->pDomTree->getNode(pBB);
    DomTreeNodeBase<BasicBlock> *pDefDomNode = pDomNode;
    while (pDomNode) {
      auto it = DomTreeMarkers.find(pDomNode);
      DXASSERT_NOMSG(it != DomTreeMarkers.end());
      if (it->second != pValue) {
        DXASSERT_NOMSG(it->second == nullptr || isa<Constant>(it->second));
        break;
      }

      pDefDomNode = pDomNode;
      pDomNode = pDomNode->getIDom();
    }

    // Handle control dependence of this constant argument highest legal "definition" point.
    pBB = pDefDomNode->getBlock();
    const BasicBlockSet &CtrlDepSet = pFuncInfo->CtrlDep.GetCDBlocks(pBB);
    for (BasicBlock *B : CtrlDepSet) {
      CollectValuesContributingToOutputRec(Entry, B->getTerminator(), ContributingInstructions);
    }
  }
}

const DxilViewIdState::ValueSetType &DxilViewIdState::CollectReachingDecls(Value *pValue) {
  auto it = m_ReachingDeclsCache.emplace(pValue, ValueSetType());
  if (it.second) {
    // We have not seen this value before.
    ValueSetType Visited;
    CollectReachingDeclsRec(pValue, it.first->second, Visited);
  }
  return it.first->second;
}

void DxilViewIdState::CollectReachingDeclsRec(Value *pValue, ValueSetType &ReachingDecls, ValueSetType &Visited) {
  if (Visited.find(pValue) != Visited.end())
    return;

  bool bInitialValue = Visited.size() == 0;
  Visited.emplace(pValue);

  if (!bInitialValue) {
    auto it = m_ReachingDeclsCache.find(pValue);
    if (it != m_ReachingDeclsCache.end()) {
      ReachingDecls.insert(it->second.begin(), it->second.end());
      return;
    }
  }

  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(pValue)) {
    ReachingDecls.emplace(pValue);
    return;
  }

  if (GetElementPtrInst *pGepInst = dyn_cast<GetElementPtrInst>(pValue)) {
    Value *pPtrValue = pGepInst->getPointerOperand();
    CollectReachingDeclsRec(pPtrValue, ReachingDecls, Visited);
  } else if (GEPOperator *pGepOp = dyn_cast<GEPOperator>(pValue)) {
    Value *pPtrValue = pGepOp->getPointerOperand();
    CollectReachingDeclsRec(pPtrValue, ReachingDecls, Visited);
  } else if (AllocaInst *AI = dyn_cast<AllocaInst>(pValue)) {
    ReachingDecls.emplace(pValue);
  } else if (PHINode *phi = dyn_cast<PHINode>(pValue)) {
    for (Value *pPtrValue : phi->operands()) {
      CollectReachingDeclsRec(pPtrValue, ReachingDecls, Visited);
    }
  } else if (SelectInst *SelI = dyn_cast<SelectInst>(pValue)) {
    CollectReachingDeclsRec(SelI->getTrueValue(), ReachingDecls, Visited);
    CollectReachingDeclsRec(SelI->getFalseValue(), ReachingDecls, Visited);
  } else if (Argument *pArg = dyn_cast<Argument>(pValue)) {
    ReachingDecls.emplace(pValue);
  } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(pValue)) {
    CollectReachingDeclsRec(BCI->getOperand(0), ReachingDecls, Visited);
  } else {
    IFT(DXC_E_GENERAL_INTERNAL_ERROR);
  }
}

const DxilViewIdState::ValueSetType &DxilViewIdState::CollectStores(llvm::Value *pValue) {
  auto it = m_StoresPerDeclCache.emplace(pValue, ValueSetType());
  if (it.second) {
    // We have not seen this value before.
    ValueSetType Visited;
    CollectStoresRec(pValue, it.first->second, Visited);
  }
  return it.first->second;
}

void DxilViewIdState::CollectStoresRec(llvm::Value *pValue, ValueSetType &Stores, ValueSetType &Visited) {
  if (Visited.find(pValue) != Visited.end())
    return;

  bool bInitialValue = Visited.size() == 0;
  Visited.emplace(pValue);

  if (!bInitialValue) {
    auto it = m_StoresPerDeclCache.find(pValue);
    if (it != m_StoresPerDeclCache.end()) {
      Stores.insert(it->second.begin(), it->second.end());
      return;
    }
  }

  if (isa<LoadInst>(pValue)) {
    return;
  } else if (isa<StoreInst>(pValue) ||
             isa<AtomicCmpXchgInst>(pValue) ||
             isa<AtomicRMWInst>(pValue)) {
    Stores.emplace(pValue);
    return;
  }

  for (auto *U : pValue->users()) {
    CollectStoresRec(U, Stores, Visited);
  }
}

void DxilViewIdState::CreateViewIdSets(const std::unordered_map<unsigned, InstructionSetType> &ContributingInstructions, 
                                       OutputsDependentOnViewIdType &OutputsDependentOnViewId,
                                       InputsContributingToOutputType &InputsContributingToOutputs,
                                       bool bPC) {
  const ShaderModel *pSM = m_pModule->GetShaderModel();

  for (auto &itOut : ContributingInstructions) {
    unsigned outIdx = itOut.first;
    for (Instruction *pInst : itOut.second) {
      // Set output dependence on ViewId.
      if (DxilInst_ViewID VID = DxilInst_ViewID(pInst)) {
        DXASSERT(m_bUsesViewId, "otherwise, DxilModule flag not set properly");
        OutputsDependentOnViewId[outIdx] = true;
        continue;
      }

      // Start setting output dependence on inputs.
      DxilSignatureElement *pSigElem = nullptr;
      bool bLoadOutputCPInHS = false;
      unsigned inpId = (unsigned)-1;
      int startRow = Semantic::kUndefinedRow, endRow = Semantic::kUndefinedRow;
      unsigned col = (unsigned)-1;
      if (DxilInst_LoadInput LI = DxilInst_LoadInput(pInst)) {
        GetUnsignedVal(LI.get_inputSigId(), &inpId);
        GetUnsignedVal(LI.get_colIndex(), &col);
        GetUnsignedVal(LI.get_rowIndex(), (uint32_t*)&startRow);
        pSigElem = &m_pModule->GetInputSignature().GetElement(inpId);
        if (pSM->IsDS() && bPC) {
          pSigElem = nullptr;
        }
      } else if (DxilInst_LoadOutputControlPoint LOCP = DxilInst_LoadOutputControlPoint(pInst)) {
        GetUnsignedVal(LOCP.get_inputSigId(), &inpId);
        GetUnsignedVal(LOCP.get_col(), &col);
        GetUnsignedVal(LOCP.get_row(), (uint32_t*)&startRow);
        if (pSM->IsHS()) {
          pSigElem = &m_pModule->GetOutputSignature().GetElement(inpId);
          bLoadOutputCPInHS = true;
        } else if (pSM->IsDS()) {
          if (!bPC) {
            pSigElem = &m_pModule->GetInputSignature().GetElement(inpId);
          }
        } else {
          DXASSERT_NOMSG(false);
        }
      } else if (DxilInst_LoadPatchConstant LPC = DxilInst_LoadPatchConstant(pInst)) {
        if (pSM->IsDS() && bPC) {
          GetUnsignedVal(LPC.get_inputSigId(), &inpId);
          GetUnsignedVal(LPC.get_col(), &col);
          GetUnsignedVal(LPC.get_row(), (uint32_t*)&startRow);
          pSigElem = &m_pModule->GetPatchConstantSignature().GetElement(inpId);
        }
      } else {
        continue;
      }

      // Finalize setting output dependence on inputs.
      if (pSigElem && pSigElem->IsAllocated()) {
        if (startRow != Semantic::kUndefinedRow) {
          endRow = startRow;
        } else {
          // The entire column contributes to output.
          startRow = 0;
          endRow = pSigElem->GetRows() - 1;
        }

        auto &ContributingInputs = InputsContributingToOutputs[outIdx];
        for (int row = startRow; row <= endRow; row++) {
          unsigned index = GetLinearIndex(*pSigElem, row, col);
          if (!bLoadOutputCPInHS) {
            ContributingInputs.emplace(index);
          } else {
            // This HS patch-constant output depends on an input value of LoadOutputControlPoint
            // that is the output value of the HS main (control-point) function.
            // Transitively update this (patch-constant) output dependence on main (control-point) output.
            DXASSERT_NOMSG(&OutputsDependentOnViewId == &m_PCOutputsDependentOnViewId);
            OutputsDependentOnViewId[outIdx] = OutputsDependentOnViewId[outIdx] || m_OutputsDependentOnViewId[0][index];

            const auto it = m_InputsContributingToOutputs[0].find(index);
            if (it != m_InputsContributingToOutputs[0].end()) {
              const std::set<unsigned> &LoadOutputCPInputsContributingToOutputs = it->second;
              ContributingInputs.insert(LoadOutputCPInputsContributingToOutputs.begin(),
                                        LoadOutputCPInputsContributingToOutputs.end());
            }
          }
        }
      }
    }
  }
}

unsigned DxilViewIdState::GetLinearIndex(DxilSignatureElement &SigElem, int row, unsigned col) const {
  DXASSERT_NOMSG(row >= 0 && col < kNumComps && SigElem.GetStartRow() != Semantic::kUndefinedRow);
  unsigned idx = (((unsigned)row) + SigElem.GetStartRow())*kNumComps + col + SigElem.GetStartCol();
  DXASSERT_NOMSG(idx < kMaxSigScalars);
  return idx;
}

void DxilViewIdState::UpdateDynamicIndexUsageState() const {
  UpdateDynamicIndexUsageStateForSig(m_pModule->GetInputSignature(), m_InpSigDynIdxElems);
  UpdateDynamicIndexUsageStateForSig(m_pModule->GetOutputSignature(), m_OutSigDynIdxElems);
  UpdateDynamicIndexUsageStateForSig(m_pModule->GetPatchConstantSignature(), m_PCSigDynIdxElems);
}

void DxilViewIdState::UpdateDynamicIndexUsageStateForSig(DxilSignature &Sig,
                                                         const DynamicallyIndexedElemsType &DynIdxElems) const {
  for (auto it : DynIdxElems) {
    unsigned id = it.first;
    unsigned mask = it.second;
    DxilSignatureElement &E = Sig.GetElement(id);
    E.SetDynIdxCompMask(mask);
  }
}

static unsigned RoundUpToUINT(unsigned x) {
  return (x + 31)/32;
}

void DxilViewIdState::Serialize() {
  const ShaderModel *pSM = m_pModule->GetShaderModel();
  m_SerializedState.clear();

  // Compute serialized state size in UINTs.
  unsigned NumInputs = getNumInputSigScalars();
  unsigned NumStreams = pSM->IsGS()? kNumStreams : 1;
  unsigned Size = 0;
  Size += 1;  // #Inputs.
  for (unsigned StreamId = 0; StreamId < NumStreams; StreamId++) {
    Size += 1;  // #Outputs for stream StreamId.
    unsigned NumOutputs = getNumOutputSigScalars(StreamId);
    unsigned NumOutUINTs = RoundUpToUINT(NumOutputs);
    if (m_bUsesViewId) {
      Size += NumOutUINTs;  // m_OutputsDependentOnViewId[StreamId]
    }
    Size += NumInputs * NumOutUINTs;  // m_InputsContributingToOutputs[StreamId]
  }
  if (pSM->IsHS() || pSM->IsDS()) {
    Size += 1;  // #PatchConstant.
    unsigned NumPCs = getNumPCSigScalars();
    unsigned NumPCUINTs = RoundUpToUINT(NumPCs);
    if (pSM->IsHS()) {
      if (m_bUsesViewId) {
        Size += NumPCUINTs;  // m_PCOutputsDependentOnViewId
      }
      Size += NumInputs * NumPCUINTs; // m_InputsContributingToPCOutputs
    } else {
      unsigned NumOutputs = getNumOutputSigScalars(0);
      unsigned NumOutUINTs = RoundUpToUINT(NumOutputs);
      Size += NumPCs * NumOutUINTs;   // m_PCInputsContributingToOutputs
    }
  }

  m_SerializedState.resize(Size);
  std::fill(m_SerializedState.begin(), m_SerializedState.end(), 0u);

  // Serialize ViewId state.
  unsigned *pData = &m_SerializedState[0];
  *pData++ = NumInputs;
  for (unsigned StreamId = 0; StreamId < NumStreams; StreamId++) {
    unsigned NumOutputs = getNumOutputSigScalars(StreamId);
    *pData++ = NumOutputs;
    if (m_bUsesViewId) {
      SerializeOutputsDependentOnViewId(NumOutputs, m_OutputsDependentOnViewId[StreamId], pData);
    }
    SerializeInputsContributingToOutput(NumInputs, NumOutputs, m_InputsContributingToOutputs[StreamId], pData);
  }
  if (pSM->IsHS() || pSM->IsDS()) {
    unsigned NumPCs = getNumPCSigScalars();
    *pData++ = NumPCs;
    if (pSM->IsHS()) {
      if (m_bUsesViewId) {
        SerializeOutputsDependentOnViewId(NumPCs, m_PCOutputsDependentOnViewId, pData);
      }
      SerializeInputsContributingToOutput(NumInputs, NumPCs, m_InputsContributingToPCOutputs, pData);
    } else {
      unsigned NumOutputs = getNumOutputSigScalars(0);
      SerializeInputsContributingToOutput(NumPCs, NumOutputs, m_PCInputsContributingToOutputs, pData);
    }
  }
  DXASSERT_NOMSG(pData == (&m_SerializedState[0] + Size));
}

const vector<unsigned> &DxilViewIdState::GetSerialized() {
  if (m_SerializedState.empty())
    Serialize();
  return m_SerializedState;
}

const vector<unsigned> &DxilViewIdState::GetSerialized() const {
  return m_SerializedState;
}

void DxilViewIdState::SerializeOutputsDependentOnViewId(unsigned NumOutputs, 
                                                        const OutputsDependentOnViewIdType &OutputsDependentOnViewId,
                                                        unsigned *&pData) {
  unsigned NumOutUINTs = RoundUpToUINT(NumOutputs);

  // Serialize output dependence on ViewId.
  for (unsigned i = 0; i < NumOutUINTs; i++) {
    unsigned x = 0;
    for (unsigned j = 0; j < std::min(32u, NumOutputs - 32u*i); j++) {
      if (OutputsDependentOnViewId[i*32 + j]) {
        x |= (1u << j);
      }
    }
    *pData++ = x;
  }
}

void DxilViewIdState::SerializeInputsContributingToOutput(unsigned NumInputs, unsigned NumOutputs,
                                                          const InputsContributingToOutputType &InputsContributingToOutputs,
                                                          unsigned *&pData) {
  unsigned NumOutUINTs = RoundUpToUINT(NumOutputs);

  // Serialize output dependence on inputs.
  for (unsigned outputIdx = 0; outputIdx < NumOutputs; outputIdx++) {
    auto it = InputsContributingToOutputs.find(outputIdx);
    if (it != InputsContributingToOutputs.end()) {
      for (unsigned inputIdx : it->second) {
        unsigned w = outputIdx / 32;
        unsigned b = outputIdx % 32;
        pData[inputIdx*NumOutUINTs + w] |= (1u << b);
      }
    }
  }

  pData += NumInputs * NumOutUINTs;
}

void DxilViewIdState::Deserialize(const unsigned *pData, unsigned DataSizeInUINTs) {
  Clear();
  m_SerializedState.resize(DataSizeInUINTs);
  memcpy(m_SerializedState.data(), pData, DataSizeInUINTs * sizeof(unsigned));

  const ShaderModel *pSM = m_pModule->GetShaderModel();
  m_bUsesViewId = m_pModule->m_ShaderFlags.GetViewID();
  unsigned ConsumedUINTs = 0;

  IFTBOOL(DataSizeInUINTs-ConsumedUINTs >= 1, DXC_E_GENERAL_INTERNAL_ERROR);
  unsigned NumInputs = pData[ConsumedUINTs++];
  m_NumInputSigScalars = NumInputs;

  unsigned NumStreams = pSM->IsGS()? kNumStreams : 1;
  for (unsigned StreamId = 0; StreamId < NumStreams; StreamId++) {
    IFTBOOL(DataSizeInUINTs-ConsumedUINTs >= 1, DXC_E_GENERAL_INTERNAL_ERROR);
    unsigned NumOutputs = pData[ConsumedUINTs++];
    m_NumOutputSigScalars[StreamId] = NumOutputs;

    if (m_bUsesViewId) {
      ConsumedUINTs += DeserializeOutputsDependentOnViewId(NumOutputs, 
                                                           m_OutputsDependentOnViewId[StreamId],
                                                           &pData[ConsumedUINTs],
                                                           DataSizeInUINTs-ConsumedUINTs);
    }
    ConsumedUINTs += DeserializeInputsContributingToOutput(NumInputs, NumOutputs,
                                                           m_InputsContributingToOutputs[StreamId],
                                                           &pData[ConsumedUINTs],
                                                           DataSizeInUINTs-ConsumedUINTs);
  }

  if (pSM->IsHS() || pSM->IsDS()) {
    IFTBOOL(DataSizeInUINTs-ConsumedUINTs >= 1, DXC_E_GENERAL_INTERNAL_ERROR);
    unsigned NumPCs = pData[ConsumedUINTs++];
    m_NumPCSigScalars = NumPCs;
    if (pSM->IsHS()) {
      if (m_bUsesViewId) {
        ConsumedUINTs += DeserializeOutputsDependentOnViewId(NumPCs, 
                                                             m_PCOutputsDependentOnViewId,
                                                             &pData[ConsumedUINTs],
                                                             DataSizeInUINTs-ConsumedUINTs);
      }
      ConsumedUINTs += DeserializeInputsContributingToOutput(NumInputs, NumPCs,
                                                             m_InputsContributingToPCOutputs,
                                                             &pData[ConsumedUINTs],
                                                             DataSizeInUINTs-ConsumedUINTs);
    } else {
      unsigned NumOutputs = getNumOutputSigScalars(0);
      ConsumedUINTs += DeserializeInputsContributingToOutput(NumPCs, NumOutputs,
                                                             m_PCInputsContributingToOutputs,
                                                             &pData[ConsumedUINTs],
                                                             DataSizeInUINTs-ConsumedUINTs);
    }
  }

  DXASSERT_NOMSG(ConsumedUINTs == DataSizeInUINTs);
}

unsigned DxilViewIdState::DeserializeOutputsDependentOnViewId(unsigned NumOutputs, 
                                                              OutputsDependentOnViewIdType &OutputsDependentOnViewId,
                                                              const unsigned *pData, unsigned DataSize) {
  unsigned NumOutUINTs = RoundUpToUINT(NumOutputs);
  IFTBOOL(NumOutUINTs <= DataSize, DXC_E_GENERAL_INTERNAL_ERROR);

  // Deserialize output dependence on ViewId.
  for (unsigned i = 0; i < NumOutUINTs; i++) {
    unsigned x = *pData++;
    for (unsigned j = 0; j < std::min(32u, NumOutputs - 32u*i); j++) {
      if (x & (1u << j)) {
        OutputsDependentOnViewId[i*32 + j] = true;
      }
    }
  }

  return NumOutUINTs;
}

unsigned DxilViewIdState::DeserializeInputsContributingToOutput(unsigned NumInputs, unsigned NumOutputs,
                                                                InputsContributingToOutputType &InputsContributingToOutputs,
                                                                const unsigned *pData, unsigned DataSize) {
  unsigned NumOutUINTs = RoundUpToUINT(NumOutputs);
  unsigned Size = NumInputs * NumOutUINTs;
  IFTBOOL(Size <= DataSize, DXC_E_GENERAL_INTERNAL_ERROR);

  // Deserialize output dependence on inputs.
  for (unsigned inputIdx = 0; inputIdx < NumInputs; inputIdx++) {
    for (unsigned outputIdx = 0; outputIdx < NumOutputs; outputIdx++) {
      unsigned w = outputIdx / 32;
      unsigned b = outputIdx % 32;
      if (pData[inputIdx*NumOutUINTs + w] & (1u << b)) {
        InputsContributingToOutputs[outputIdx].insert(inputIdx);
      }
    }
  }

  return Size;
}

char ComputeViewIdState::ID = 0;

INITIALIZE_PASS_BEGIN(ComputeViewIdState, "viewid-state",
                "Compute information related to ViewID", true, true)
INITIALIZE_PASS_END(ComputeViewIdState, "viewid-state",
                "Compute information related to ViewID", true, true)

ComputeViewIdState::ComputeViewIdState() : ModulePass(ID) {
}

bool ComputeViewIdState::runOnModule(Module &M) {
  DxilModule &DxilModule = M.GetOrCreateDxilModule();
  const ShaderModel *pSM = DxilModule.GetShaderModel();
  if (!pSM->IsCS() && !pSM->IsLib()) {
    DxilViewIdState &ViewIdState = DxilModule.GetViewIdState();
    ViewIdState.Compute();
    return true;
  }
  return false;
}

void ComputeViewIdState::getAnalysisUsage(AnalysisUsage &AU) const {
  AU.setPreservesAll();
}


namespace llvm {

ModulePass *createComputeViewIdStatePass() {
  return new ComputeViewIdState();
}

} // end of namespace llvm