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

Copyright (c) 2017 Intel Corporation

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======================= end_copyright_notice ==================================*/
#pragma once

#include "common/LLVMWarningsPush.hpp"
#include <llvm/Pass.h>
#include <llvm/IR/DataLayout.h>
#include <llvm/IR/InstVisitor.h>
#include "common/LLVMWarningsPop.hpp"

namespace IGC
{

    /// @brief  This pass correctly sets the alignment of all loads
    ///         and stores according to OpenCL rules.
    ///         It perform a data-flow analysis to keep track of the highest power
    ///         of 2 that divides a value.
    ///         This tracking is performed for integers and for pointers, and is
    ///         based on the assumption that global variables and kernel arguments
    ///         are always aligned on their data type.
    ///         The result is an underapproximation of the actual alignment, so it
    ///         is always safe.
    class AlignmentAnalysis : public llvm::FunctionPass, public llvm::InstVisitor<AlignmentAnalysis, unsigned int>
    {
    public:
        // Pass identification, replacement for typeid
        static char ID;

        /// @brief  Constructor
        AlignmentAnalysis();

        /// @brief  Destructor
        ~AlignmentAnalysis() {}

        /// @brief  Provides name of pass
        virtual llvm::StringRef getPassName() const override
        {
            return "AlignmentAnalysisPass";
        }

        virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override
        {
            AU.setPreservesCFG();
        }

        /// @brief  Main entry point.
        virtual bool runOnFunction(llvm::Function &F) override;

        // @ brief Instruction visitors
        unsigned int visitInstruction(llvm::Instruction &I);
        unsigned int visitAllocaInst(llvm::AllocaInst &I);
        unsigned int visitIntToPtrInst(llvm::IntToPtrInst &I);
        unsigned int visitPtrToIntInst(llvm::PtrToIntInst &I);
        unsigned int visitSelectInst(llvm::SelectInst &I);
        unsigned int visitGetElementPtrInst(llvm::GetElementPtrInst &I);
        unsigned int visitPHINode(llvm::PHINode &I);
        unsigned int visitBitCastInst(llvm::BitCastInst &I);
        unsigned int visitLoadInst(llvm::LoadInst &I);
        unsigned int visitStoreInst(llvm::StoreInst &I);
        unsigned int visitAdd(llvm::BinaryOperator &I);
        unsigned int visitMul(llvm::BinaryOperator &I);
        unsigned int visitShl(llvm::BinaryOperator &I);
        unsigned int visitAnd(llvm::BinaryOperator &I);
        unsigned int visitTruncInst(llvm::TruncInst &I);
        unsigned int visitZExtInst(llvm::ZExtInst &I);
        unsigned int visitSExtInst(llvm::SExtInst &I);
        unsigned int visitCallInst(llvm::CallInst &I);
        unsigned int visitMemSetInst(llvm::MemSetInst &I);
        unsigned int visitMemCpyInst(llvm::MemCpyInst &I);
        unsigned int visitMemMoveInst(llvm::MemMoveInst &I);

    protected:
        /// @breif Evaluates the alignment of I based on its operands.
        ///        For Load and Store instructions, also sets the alignment
        ///        of the operation itself.
        /// @param I The instruction to process
        bool processInstruction(llvm::Instruction* I);

        /// @brief Returns the alignment for V, if it is known.
        ///        Otherwise, returns the maximum alignment.
        /// @param V the value the alignment of which we're interested in
        unsigned int getAlignValue(llvm::Value *V) const;

        /// @brief Returns the alignment of a constant integer.
        ///        This is normally 1 << ctz(C) (the highest power of 2 that divides C), 
        ///        except when C is 0, when it is the max alignment
        unsigned int getConstantAlignment(uint64_t C) const;

        /// @brief This map stores the known alignment of every value.
        std::map<llvm::Value*, unsigned int> m_alignmentMap;

        static const unsigned int MinimumAlignment = 1;

        const llvm::DataLayout *m_DL;
    };

} // namespace IGC
