include/cg/memlayout.h

/*
 * Copyright (c) 2023 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef MAPLEBE_INCLUDE_CG_MEMLAYOUT_H
#define MAPLEBE_INCLUDE_CG_MEMLAYOUT_H

/* C++ headers. */
#include <utility>
#include "becommon.h"
#include "mir_function.h"
#include "mir_nodes.h" /* StmtNode */

namespace maplebe {
using regno_t = uint32;
enum MemSegmentKind : uint8 {
    kMsUnknown,
    /*
     * Function arguments that are not passed through registers
     * are passed to the callee through stack.
     */
    kMsArgsStkPassed,
    /*
     * In between MS_args_stackpassed and kMsArgsRegpassed,
     * we store call-saved registers if any.
     */
    /*
     * Args passed via registers according to the architecture-specific ABI
     * may need be stored in stack.
     * 1) In the unoptimized version, we implement a model (similar to GCC -O0)
     *    where all the values are initially stored in the memory and
     *    loaded into registers when needed, and stored back to the memory when
     *    their uses are done.
     * 2) In an optimized version, some register-passed values may need to be
     *    spilled into memory. We allocate the space in this Memory segment.
     *    (or we may allocate them in caller-saved; may be this is better...)
     */
    kMsArgsRegPassed,
    /*
     * GR/VR Save areas for unnamed arguments under vararg functions
     */
    kMsGrSaveArea,
    kMsVrSaveArea,
    /* local (auto) variables */
    kMsRefLocals,
    kMsLocals,
    // segment which is accessed rarely
    kMsCold,
    kMsSpillReg,
    /*
     * In between kMsLocals and MS_args_to_stackpass, we allocate
     * a register-spill area and space for caller-saved registers
     */
    /*
     * When a function calls another which takes some arguments
     * that cannot be passed through registers, it is the caller's
     * responsibility to allocate space for those arguments in memory.
     */
    kMsArgsToStkPass,
    /* The red zone stack area will not be modified by the exception signal. */
    kMsRedZone,
};

enum StackProtectKind : uint8 {
    kNone = 0,
    kAddrofStack = 0x1,
    /* if a callee has return agg type which size over 16bytes */
    kRetureStackSlot = 0x2,
};

class CGFunc;

/* keeps track of the allocation of a memory segment */
class MemSegment {
public:
    explicit MemSegment(MemSegmentKind memSegKind) : kind(memSegKind), size(0) {}

    ~MemSegment() = default;

    uint32 GetSize() const
    {
        return size;
    }

    void SetSize(uint32 memSize)
    {
        size = memSize;
    }

    MemSegmentKind GetMemSegmentKind() const
    {
        return kind;
    }

private:
    MemSegmentKind kind;
    uint32 size; /* size is negative if allocated offsets are negative */
};               /* class MemSegment */

/* describes where a symbol is allocated */
class SymbolAlloc {
public:
    SymbolAlloc() = default;

    ~SymbolAlloc() = default;

    const MemSegment *GetMemSegment() const
    {
        return memSegment;
    }

    void SetMemSegment(const MemSegment &memSeg)
    {
        memSegment = &memSeg;
    }

    int64 GetOffset() const
    {
        return offset;
    }

    void SetOffset(int64 off)
    {
        offset = off;
    }

protected:
    const MemSegment *memSegment = nullptr;
    int64 offset = 0;
}; /* class SymbolAlloc */

class MemLayout {
public:
    MemLayout(BECommon &beCommon, MIRFunction &mirFunc, MapleAllocator &mallocator, uint32 kStackPtrAlignment)
        : be(beCommon),
          mirFunction(&mirFunc),
          segArgsStkPassed(kMsArgsStkPassed),
          segArgsRegPassed(kMsArgsRegPassed),
          segArgsToStkPass(kMsArgsToStkPass),
          symAllocTable(mallocator.Adapter()),
          spillLocTable(mallocator.Adapter()),
          spillRegLocMap(mallocator.Adapter()),
          localRefLocMap(std::less<StIdx>(), mallocator.Adapter()),
          memAllocator(&mallocator),
          stackPtrAlignment(kStackPtrAlignment)
    {
        symAllocTable.resize(mirFunc.GetSymTab()->GetSymbolTableSize());
    }

    virtual ~MemLayout() = default;

    void SetCurrFunction(CGFunc &func)
    {
        cgFunc = &func;
    }

    /*
     * Returns stack space required for a call
     * which is used to pass arguments that cannot be
     * passed through registers
     */
    virtual uint32 ComputeStackSpaceRequirementForCall(StmtNode &stmtNode, int32 &aggCopySize, bool isIcall) = 0;

    /*
     * Go over all outgoing calls in the function body and get the maximum space
     * needed for storing the actuals based on the actual parameters and the ABI.
     * These are usually those arguments that cannot be passed
     * through registers because a call passes more than 8 arguments, or
     * they cannot be fit in a pair of registers.
     */
    uint32 FindLargestActualArea(int32 &aggCopySize);

    virtual void LayoutStackFrame(int32 &structCopySize, int32 &maxParmStackSize) = 0;

    /*
     * "Pseudo-registers can be regarded as local variables of a
     * primitive type whose addresses are never taken"
     */
    virtual void AssignSpillLocationsToPseudoRegisters() = 0;

    virtual int32 GetCalleeSaveBaseLoc() const
    {
        return 0;
    }

    SymbolAlloc *GetSymAllocInfo(uint32 stIdx)
    {
        DEBUG_ASSERT(stIdx < symAllocTable.size(), "out of symAllocTable's range");
        return symAllocTable[stIdx];
    }

    void SetSymAllocInfo(uint32 stIdx, SymbolAlloc &symAlloc)
    {
        DEBUG_ASSERT(stIdx < symAllocTable.size(), "out of symAllocTable's range");
        symAllocTable[stIdx] = &symAlloc;
    }

    const SymbolAlloc *GetSpillLocOfPseduoRegister(PregIdx index) const
    {
        return spillLocTable.at(index);
    }

    SymbolAlloc *AssignLocationToSpillReg(regno_t vrNum, uint32 memByteSize)
    {
        auto *symLoc = CreateSymbolAlloc();
        symLoc->SetMemSegment(segSpillReg);
        segSpillReg.SetSize(static_cast<uint32>(RoundUp(segSpillReg.GetSize(), memByteSize)));
        symLoc->SetOffset(segSpillReg.GetSize());
        segSpillReg.SetSize(segSpillReg.GetSize() + memByteSize);
        SetSpillRegLocInfo(vrNum, *symLoc);
        return symLoc;
    }

    SymbolAlloc *GetLocOfSpillRegister(regno_t vrNum, uint32 memByteSize)
    {
        SymbolAlloc *loc = nullptr;
        auto pos = spillRegLocMap.find(vrNum);
        if (pos == spillRegLocMap.end()) {
            loc = AssignLocationToSpillReg(vrNum, memByteSize);
        } else {
            loc = pos->second;
        }
        return loc;
    }

    uint32 SizeOfArgsToStackPass() const
    {
        return segArgsToStkPass.GetSize();
    }

    uint32 SizeOfArgsRegisterPassed() const
    {
        return segArgsRegPassed.GetSize();
    }

    uint32 GetSizeOfSegCold() const
    {
        return segCold.GetSize();
    }

    BECommon &GetBECommon()
    {
        return be;
    }

    MIRFunction *GetMIRFunction()
    {
        return mirFunction;
    }

    const MemSegment &GetSegArgsStkPassed() const
    {
        return segArgsStkPassed;
    }

    const MemSegment &GetSegArgsRegPassed() const
    {
        return segArgsRegPassed;
    }

    const MemSegment &GetSegArgsToStkPass() const
    {
        return segArgsToStkPass;
    }

    const MapleVector<SymbolAlloc *> &GetSymAllocTable() const
    {
        return symAllocTable;
    }

    void SetSpillRegLocInfo(regno_t regNum, SymbolAlloc &symAlloc)
    {
        spillRegLocMap[regNum] = &symAlloc;
    }

    const MapleMap<StIdx, SymbolAlloc *> &GetLocalRefLocMap() const
    {
        return localRefLocMap;
    }

    void SetLocalRegLocInfo(StIdx idx, SymbolAlloc &symAlloc)
    {
        localRefLocMap[idx] = &symAlloc;
    }

    bool IsLocalRefLoc(const MIRSymbol &symbol) const
    {
        return localRefLocMap.find(symbol.GetStIdx()) != localRefLocMap.end();
    }

    uint32 GetStackPtrAlignment() const
    {
        return stackPtrAlignment;
    }

protected:
    BECommon &be;
    MIRFunction *mirFunction;
    MemSegment segArgsStkPassed;
    MemSegment segArgsRegPassed;
    MemSegment segArgsToStkPass;
    MemSegment segCold = MemSegment(kMsCold);
    MemSegment segSpillReg = MemSegment(kMsSpillReg);
    MapleVector<SymbolAlloc *> symAllocTable; /* index is stindex from StIdx */
    MapleVector<SymbolAlloc *> spillLocTable; /* index is preg idx */
    MapleUnorderedMap<regno_t, SymbolAlloc *> spillRegLocMap;
    MapleMap<StIdx, SymbolAlloc *> localRefLocMap; /* localrefvar formals. real address passed in stack. */
    MapleAllocator *memAllocator;
    CGFunc *cgFunc = nullptr;
    const uint32 stackPtrAlignment;
    virtual SymbolAlloc *CreateSymbolAlloc() const = 0;
};
} /* namespace maplebe */

#endif /* MAPLEBE_INCLUDE_CG_MEMLAYOUT_H */