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

Copyright (c) 2017 Intel Corporation

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

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

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


======================= end_copyright_notice ==================================*/
#include "TypesLegalizationPass.hpp"
#include "../Compiler/IGCPassSupport.h"
using namespace llvm;

// Register pass to igc-opt
#define PASS_FLAG "types-legalization-pass"
#define PASS_DESCRIPTION "Types Legalization pass"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false

IGC_INITIALIZE_PASS_BEGIN( TypesLegalizationPass,PASS_FLAG,PASS_DESCRIPTION,PASS_CFG_ONLY,PASS_ANALYSIS )
IGC_INITIALIZE_PASS_END( TypesLegalizationPass,PASS_FLAG,PASS_DESCRIPTION,PASS_CFG_ONLY,PASS_ANALYSIS )
char TypesLegalizationPass::ID = 0;

TypesLegalizationPass::TypesLegalizationPass()
  : FunctionPass( TypesLegalizationPass::ID ) {
  initializeTypesLegalizationPassPass( *PassRegistry::getPassRegistry() );
}

TypesLegalizationPass::TypesLegalizationPass(bool legalizePhi, bool legalizeExtractValue, bool legalizeStore)
  : FunctionPass( TypesLegalizationPass::ID ), 
    m_LegalizePhi(legalizePhi), 
    m_LegalizeExtractValue(legalizeExtractValue),
    m_LegalizeStore(legalizeStore) {
  initializeTypesLegalizationPassPass( *PassRegistry::getPassRegistry() );
}

void TypesLegalizationPass::visitExtractValueInst( ExtractValueInst &ev ) {
  if(m_LegalizeExtractValue)
  {
    m_ExtractValueInst.push_back(&ev);
  }
}

void TypesLegalizationPass::visitStoreInst( StoreInst &storeInst ) {
  if(m_LegalizeStore)
  {
    Value *arg = storeInst.getOperand( 0 );
    if(arg != NULL)
    {
      Type *type = arg->getType();

      if((type != NULL) && type->isAggregateType()) {
        m_StoreInst.push_back( &storeInst );
      }
    }
  }
}

void TypesLegalizationPass::visitPHINode( PHINode &phi ) {
  if(m_LegalizePhi)
  {
    Type *type = phi.getType();
    
    if((type != NULL) && type->isAggregateType()) {
      m_PhiNodes.push_back( &phi );
    }
  }
}

///////////////////////////////////////////////////////////////////////
/// @brief Creates an alloca instruction at the beginning of current
/// function
/// @param phi instruction to create the alloca for
AllocaInst* TypesLegalizationPass::CreateAlloca( Instruction *inst ) {
  PHINode *phi = dyn_cast<PHINode>(inst);
  if( phi != NULL)
  {
    IRBuilder<> builder( phi );
    Function *curFunc = builder.GetInsertBlock()->getParent();
    BasicBlock &firstBB = curFunc->getEntryBlock();
    BasicBlock::iterator firstInsertPoint = firstBB.getFirstInsertionPt();

    builder.SetInsertPoint( &(*firstInsertPoint) );
    Type *allocaType = phi->getType();
    return builder.CreateAlloca( allocaType );
  }
  else
  {
    return NULL;
  }
}

///////////////////////////////////////////////////////////////////////
/// @brief Creates GEP instruction.
/// @param  builder llvm IR builder to use
/// @param  ptr memory pointer to
/// @param  indices set of constant indices to use in GEP
/// @return Value* - GetElementPtrInst* instruction.
Value* TypesLegalizationPass::CreateGEP( IRBuilder<> &builder,Value *ptr,SmallVector<unsigned,8> &indices ) {
  SmallVector<   Value *,8> gepIndices;
  gepIndices.reserve( indices.size() + 1 );
  gepIndices.push_back( builder.getInt32( 0 ) );
  for(unsigned idx : indices) {
    gepIndices.push_back( builder.getInt32( idx ) );
  }
  return builder.CreateGEP( ptr,gepIndices );
}

///////////////////////////////////////////////////////////////////////
/// @brief Resolves a PHI node to alloca store and load.
/// @param phi instruction to resolve

void TypesLegalizationPass::ResolvePhiNode( PHINode *phi ) {
  AllocaInst *allocaPtr = TypesLegalizationPass::CreateAlloca( phi );
  if(allocaPtr != NULL)
  {
    for(unsigned i = 0; i < phi->getNumOperands(); ++i)
    {
      IRBuilder<> builder( phi->getIncomingBlock( i )->getTerminator() );
      Value* source = phi->getOperand( i );
      StoreInst* newStore = builder.CreateStore( source,allocaPtr );
      m_StoreInst.push_back( newStore );
    }
    IRBuilder<> builder( phi );
    BasicBlock *block = builder.GetInsertBlock();
    builder.SetInsertPoint( &(*block->getFirstInsertionPt()) );
    Value* newLoad = builder.CreateLoad( allocaPtr );
    phi->replaceAllUsesWith( newLoad );
    phi->eraseFromParent();
  }
}

///////////////////////////////////////////////////////////////////////
/// @brief Resolves the use of composite types (i.e. structures or 
/// arrays of vectors) in store and PHI nodes. 
/// PHI node are resolved to alloca store and loads. Store instructions
/// of composite values are resolved to GEP + store of individual 
/// elements of composite type.
bool TypesLegalizationPass::LegalizeTypes() {
  bool modified = false;

  // Handle PHI nodes before store instruction as the code creates
  // new store instructions.
  for(PHINode *phi : m_PhiNodes) {
    TypesLegalizationPass::ResolvePhiNode( phi );
    modified = true;
  }

  for(ExtractValueInst *ev : m_ExtractValueInst) {
    TypesLegalizationPass::ResolveExtractValue( ev );
    modified = true;
  }

  for(StoreInst *st : m_StoreInst) {
    TypesLegalizationPass::ResolveStoreInst( st );
    modified = true;
  }
  return modified;
}

///////////////////////////////////////////////////////////////////////
/// @brief Finds a structure field or array element pointed by indices
/// @param  ip insert point for new instructions
/// @param  val is a structure or array to extract the elements from
/// @param  indices specify array element or structure field to get
/// @return    Value* array element or structure field
Value *
TypesLegalizationPass::ResolveValue( Instruction *ip,Value *val,SmallVector<unsigned,8> &indices ) {

  if(InsertValueInst *civ = dyn_cast<InsertValueInst>(val)) {
    ArrayRef<unsigned> civIndices = civ->getIndices();
    if(indices.size() < civIndices.size()) {
      // We have less indices collected than it is needed to reference scalar value
      // inserted here. We will skip this instruction and anticipate there is further
      // ExtractValue further that will specify missing indices.
      return nullptr;
    }
    unsigned i = 0;
    for(; i < civIndices.size(); ++i) {
      if(civIndices[i] != indices[i]) {
        break;
      }
    }
    if(i == civIndices.size()) {
      if(i == indices.size()) {
        return civ->getInsertedValueOperand();
      }
      SmallVector<unsigned,8> ri( &indices[i],indices.end() );
      return ResolveValue( civ,civ->getInsertedValueOperand(),ri );
    }
    return ResolveValue( civ,civ->getAggregateOperand(),indices );
  }
  else if(InsertElementInst* ie =
    dyn_cast<InsertElementInst>(val))
  {
    IRBuilder<> builder( ie );
    assert( indices.size() == 1 );
    return builder.CreateExtractElement( ie,builder.getInt32( indices[0] ) );
  }
  else if(LoadInst* ld = dyn_cast<LoadInst>(val))
  {
    IRBuilder<> builder( ld );
    Value* gep = CreateGEP( builder,ld->getOperand( 0 ),indices );
    return builder.CreateLoad( gep );
  }
  else if(Constant *c = dyn_cast<Constant>(val)) {
    IRBuilder<> builder( ip );
    // Create ExtractValue - it will be folded.
    return builder.CreateExtractValue( c,indices );
  }
  else if(ExtractValueInst* ev =
    dyn_cast<ExtractValueInst>(val))
  {
    auto evi = ev->getIndices();
    SmallVector<unsigned,8> newIndices( evi.begin(),evi.end() );
    newIndices.append( &indices.front(),&indices.back() );

    return ResolveValue( ev,ev->getAggregateOperand(),newIndices );
  }
  else if (auto *II = dyn_cast<IntrinsicInst>(val))
  {
	  switch (II->getIntrinsicID())
	  {
	  case Intrinsic::uadd_with_overflow:
	  {
		  // This gets handled in the legalizer.
		  IRBuilder<> builder(ip);
		  return builder.CreateExtractValue(val, indices);
	  }
	  default:
		  break;
	  }
  }
  else if ((isa<Argument>(val) || isa<CallInst>(val)) &&
    val->getType()->isStructTy()) { 
    // Handle struct arguments and structs returned by function calls.
    IRBuilder<> builder(ip);
    return builder.CreateExtractValue(val, indices);
  }
    else if (PHINode* phi = dyn_cast<PHINode>(val))
    {
        IRBuilder<> builder(&(*ip->getParent()->getFirstInsertionPt()));
        PHINode* newPhi = builder.CreatePHI(ip->getType(), phi->getNumIncomingValues());
        for (unsigned i = 0; i < phi->getNumIncomingValues(); i++)
        {
            Value* v = ResolveValue(ip, phi->getIncomingValue(i), indices);
            newPhi->addIncoming(v, phi->getIncomingBlock(i));
        }
        return newPhi;
    }

  // What other kind of instruction can we have here?
  assert( !"Unresolved instruction!" );

  // Fallback by creating an ExtractValueInstr.
  IRBuilder<> builder( ip );
  return builder.CreateExtractValue( val,indices );
}

///////////////////////////////////////////////////////////////////////
/// @brief Resolves extract value instructions of composite types into 
/// sequences of GEP + load
/// @param  evInst instruction being resolved
/// @param  type    Type* type of current strucuter field or array 
/// element being resolved
/// @param  indices leading to current structure filed or array element 
void TypesLegalizationPass::ResolveExtractValue( ExtractValueInst* evInst )
{
  IRBuilder<>  builder( evInst );
  auto evIndices = evInst->getIndices();
  SmallVector<unsigned,8> indices( evIndices.begin(),evIndices.end() );

  Value* val = ResolveValue( evInst,evInst->getOperand( 0 ),indices );
  if(val)
  {
    evInst->replaceAllUsesWith( val );
    evInst->eraseFromParent();
  }
}

///////////////////////////////////////////////////////////////////////
/// @brief Resolves store instructions of composite types into 
/// sequences of GEP + store
/// @param  storeInst instruction to be resolved
/// @param  type    Type* type of current strucuter field or array 
/// element being resolved
/// @param  indices leading to current structure filed or array element 
void TypesLegalizationPass::ResolveStoreInst(
  StoreInst *storeInst,Type *type,
  SmallVector<unsigned,8> &indices ) {

  if(type->isStructTy()) {
    for(unsigned field = 0; field < type->getStructNumElements(); field++) {
      indices.push_back( field );
      ResolveStoreInst( storeInst,type->getStructElementType( field ),indices );
      indices.pop_back();
    }
  }
  else if(type->isArrayTy()) {
    for(unsigned elem = 0; elem < type->getArrayNumElements(); ++elem) {
      indices.push_back( elem );
      ResolveStoreInst( storeInst,type->getArrayElementType(),indices );
      indices.pop_back();
    }
  }
  else {
    Value *val =
      ResolveValue( storeInst,storeInst->getOperand( 0 ),indices );
    IRBuilder<> builder( storeInst );
    Value *pGEP = CreateGEP( builder,storeInst->getOperand( 1 ),indices );
    builder.CreateStore( val,pGEP );
  }
}

///////////////////////////////////////////////////////////////////////
/// @brief Resolves store instructions of composite types into 
/// sequences of GEP + store
/// @param  storeInst instruction to be resolved
void TypesLegalizationPass::ResolveStoreInst( StoreInst *storeInst ) {
  SmallVector<unsigned,8> indices;
  Value *arg = storeInst->getOperand( 0 );
  if(arg != NULL)
  {
    ResolveStoreInst( storeInst,arg->getType(),indices );
    storeInst->eraseFromParent();
  }
}

bool TypesLegalizationPass::runOnFunction( Function &function ) {
  this->visit( function );
  bool shaderModified = LegalizeTypes();
  m_StoreInst.clear();
  m_ExtractValueInst.clear();
  m_PhiNodes.clear();
  return shaderModified;
}
