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#include "Compiler/Optimizer/OpenCLPasses/BIFTransforms/BIFTransforms.hpp"
#include "Compiler/IGCPassSupport.h"

#include "common/igc_regkeys.hpp"

#include "common/LLVMWarningsPush.hpp"
#include "llvm/IR/Module.h"
#include "llvm/IR/Function.h"
#include "llvm/ADT/StringRef.h"
#include "common/LLVMWarningsPop.hpp"

using namespace llvm;

namespace {

class BIFTransforms : public ModulePass
{
public:
    static char ID;
    virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const
    {
        AU.setPreservesCFG();
    }

    BIFTransforms();

    ~BIFTransforms() {}

    virtual bool runOnModule(Module &M);

    virtual llvm::StringRef getPassName() const
    {
        return "BIFTransforms";
    }

private:
    // Replace some BI Functions with faster versions, such as
    // length --> fast_length, etc.
    bool replaceBIF(Function& F);
};

} // namespace

// Register pass to igc-opt
#define PASS_FLAG "igc-bif-transforms"
#define PASS_DESCRIPTION "Perform BIF-related transformations, such as replacing length with fast_length, etc"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
IGC_INITIALIZE_PASS_BEGIN(BIFTransforms, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_END(BIFTransforms, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)


char BIFTransforms::ID = 0;

BIFTransforms::BIFTransforms() : ModulePass(ID)
{
    initializeBIFTransformsPass(*PassRegistry::getPassRegistry());
}

bool BIFTransforms::replaceBIF(Function& F)
{
    // replace
    //    length --> fast_length
    //    normalize --> fast_normaliez
    //    distance --> fast_distance
    // As the fast version only exists for float/double in BIF, not half,
    // here make sure F is not half before replacing.
    Function::arg_iterator AI = F.arg_begin();
    if (AI == F.arg_end())
    {
        return false;
    }
    Type *Ty = AI->getType();
    if (Ty->isHalfTy() ||
        (Ty->isVectorTy() && Ty->getVectorElementType()->isHalfTy()))
    {
        return false;
    }

    bool changed = false;
    StringRef name = F.getName();
    if (name.startswith("_Z6length"))
    {   // length --> fast_length
        std::string newName("_Z11fast_length");
        newName.append(name.data() + 9);
        F.setName(newName);
        changed = true;
    }
    else if (name.startswith("_Z9normalize"))
    {   // normalize --> fast_normalize
        std::string newName("_Z14fast_normalize");
        newName.append(name.data() + 12);
        F.setName(newName);
        changed = true;
    }
    else if (name.startswith("_Z8distance"))
    {   // distance --> fast_distance
        std::string newName("_Z13fast_distance");
        newName.append(name.data() + 11);
        F.setName(newName);
        changed = true;
    }

    return changed;
}

bool BIFTransforms::runOnModule(Module &M)
{
    // OCL builtin uses SPIR name mangling (Itanium C++ ABI + extension)
    //  mangledName (n) = _Z<lengthof(n)><n><type> 
    bool changed = false;
    for (Function &F : M)
    {
        if (F.isDeclaration())
        {
            if (IGC_IS_FLAG_ENABLED(EnableIntelFast) && replaceBIF(F))
            {
                changed = true;

            }
        }
    }
    return changed;
}
 
// Public interface to this pass
ModulePass *createBIFTransformsPass()
{
    return new BIFTransforms();
}
