path: root/src/jit/lowerarmarch.cpp

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

/*XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XX                                                                           XX
XX             Lowering for ARM and ARM64 common code                        XX
XX                                                                           XX
XX  This encapsulates common logic for lowering trees for the ARM and ARM64  XX
XX  architectures.  For a more detailed view of what is lowering, please     XX
XX  take a look at Lower.cpp                                                 XX
XX                                                                           XX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
*/

#include "jitpch.h"
#ifdef _MSC_VER
#pragma hdrstop
#endif

#ifndef LEGACY_BACKEND // This file is ONLY used for the RyuJIT backend that uses the linear scan register allocator

#ifdef _TARGET_ARMARCH_ // This file is ONLY used for ARM and ARM64 architectures

#include "jit.h"
#include "sideeffects.h"
#include "lower.h"
#include "lsra.h"

//------------------------------------------------------------------------
// LowerStoreLoc: Lower a store of a lclVar
//
// Arguments:
//    storeLoc - the local store (GT_STORE_LCL_FLD or GT_STORE_LCL_VAR)
//
// Notes:
//    This involves:
//    - Widening operations of unsigneds.
//
void Lowering::LowerStoreLoc(GenTreeLclVarCommon* storeLoc)
{
    // Try to widen the ops if they are going into a local var.
    GenTree* op1 = storeLoc->gtGetOp1();
    if ((storeLoc->gtOper == GT_STORE_LCL_VAR) && (op1->gtOper == GT_CNS_INT))
    {
        GenTreeIntCon* con    = op1->AsIntCon();
        ssize_t        ival   = con->gtIconVal;
        unsigned       varNum = storeLoc->gtLclNum;
        LclVarDsc*     varDsc = comp->lvaTable + varNum;

        if (varDsc->lvIsSIMDType())
        {
            noway_assert(storeLoc->gtType != TYP_STRUCT);
        }
        unsigned size = genTypeSize(storeLoc);
        // If we are storing a constant into a local variable
        // we extend the size of the store here
        if ((size < 4) && !varTypeIsStruct(varDsc))
        {
            if (!varTypeIsUnsigned(varDsc))
            {
                if (genTypeSize(storeLoc) == 1)
                {
                    if ((ival & 0x7f) != ival)
                    {
                        ival = ival | 0xffffff00;
                    }
                }
                else
                {
                    assert(genTypeSize(storeLoc) == 2);
                    if ((ival & 0x7fff) != ival)
                    {
                        ival = ival | 0xffff0000;
                    }
                }
            }

            // A local stack slot is at least 4 bytes in size, regardless of
            // what the local var is typed as, so auto-promote it here
            // unless it is a field of a promoted struct
            // TODO-CQ: if the field is promoted shouldn't we also be able to do this?
            if (!varDsc->lvIsStructField)
            {
                storeLoc->gtType = TYP_INT;
                con->SetIconValue(ival);
            }
        }
    }
}

//------------------------------------------------------------------------
// LowerBlockStore: Set block store type
//
// Arguments:
//    blkNode       - The block store node of interest
//
// Return Value:
//    None.
//
void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
{
    GenTree*  dstAddr  = blkNode->Addr();
    unsigned  size     = blkNode->gtBlkSize;
    GenTree*  source   = blkNode->Data();
    Compiler* compiler = comp;

    // Sources are dest address and initVal or source.
    GenTreePtr srcAddrOrFill = nullptr;
    bool       isInitBlk     = blkNode->OperIsInitBlkOp();

    if (!isInitBlk)
    {
        // CopyObj or CopyBlk
        if ((blkNode->OperGet() == GT_STORE_OBJ) && ((blkNode->AsObj()->gtGcPtrCount == 0) || blkNode->gtBlkOpGcUnsafe))
        {
            blkNode->SetOper(GT_STORE_BLK);
        }
        if (source->gtOper == GT_IND)
        {
            srcAddrOrFill = blkNode->Data()->gtGetOp1();
        }
    }

    if (isInitBlk)
    {
        GenTreePtr initVal = source;
        if (initVal->OperIsInitVal())
        {
            initVal = initVal->gtGetOp1();
        }
        srcAddrOrFill = initVal;

#ifdef _TARGET_ARM64_
        if ((size != 0) && (size <= INITBLK_UNROLL_LIMIT) && initVal->IsCnsIntOrI())
        {
            // TODO-ARM-CQ: Currently we generate a helper call for every
            // initblk we encounter.  Later on we should implement loop unrolling
            // code sequences to improve CQ.
            // For reference see the code in LowerXArch.cpp.
            NYI_ARM("initblk loop unrolling is currently not implemented.");

            // The fill value of an initblk is interpreted to hold a
            // value of (unsigned int8) however a constant of any size
            // may practically reside on the evaluation stack. So extract
            // the lower byte out of the initVal constant and replicate
            // it to a larger constant whose size is sufficient to support
            // the largest width store of the desired inline expansion.

            ssize_t fill = initVal->gtIntCon.gtIconVal & 0xFF;
            if (size < REGSIZE_BYTES)
            {
                initVal->gtIntCon.gtIconVal = 0x01010101 * fill;
            }
            else
            {
                initVal->gtIntCon.gtIconVal = 0x0101010101010101LL * fill;
                initVal->gtType             = TYP_LONG;
            }
            blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;
        }
        else
#endif // _TARGET_ARM64_
        {
            blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindHelper;
        }
    }
    else
    {
        // CopyObj or CopyBlk
        // Sources are src and dest and size if not constant.

        if (blkNode->OperGet() == GT_STORE_OBJ)
        {
            // CopyObj

            NYI_ARM("Lowering for GT_STORE_OBJ isn't implemented");

#ifdef _TARGET_ARM64_

            GenTreeObj* objNode = blkNode->AsObj();

            unsigned slots = objNode->gtSlots;

#ifdef DEBUG
            // CpObj must always have at least one GC-Pointer as a member.
            assert(objNode->gtGcPtrCount > 0);

            assert(dstAddr->gtType == TYP_BYREF || dstAddr->gtType == TYP_I_IMPL);

            CORINFO_CLASS_HANDLE clsHnd    = objNode->gtClass;
            size_t               classSize = compiler->info.compCompHnd->getClassSize(clsHnd);
            size_t               blkSize   = roundUp(classSize, TARGET_POINTER_SIZE);

            // Currently, the EE always round up a class data structure so
            // we are not handling the case where we have a non multiple of pointer sized
            // struct. This behavior may change in the future so in order to keeps things correct
            // let's assert it just to be safe. Going forward we should simply
            // handle this case.
            assert(classSize == blkSize);
            assert((blkSize / TARGET_POINTER_SIZE) == slots);
            assert(objNode->HasGCPtr());
#endif

            blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;

#endif // _TARGET_ARM64_
        }
        else
        {
            // CopyBlk
            short     internalIntCount      = 0;
            regMaskTP internalIntCandidates = RBM_NONE;

#ifdef _TARGET_ARM64_
            // In case of a CpBlk with a constant size and less than CPBLK_UNROLL_LIMIT size
            // we should unroll the loop to improve CQ.
            // For reference see the code in lowerxarch.cpp.
            // TODO-ARM-CQ: cpblk loop unrolling is currently not implemented.

            if ((size != 0) && (size <= INITBLK_UNROLL_LIMIT))
            {
                blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;
            }
            else
#endif // _TARGET_ARM64_
            {
                // In case we have a constant integer this means we went beyond
                // CPBLK_UNROLL_LIMIT bytes of size, still we should never have the case of
                // any GC-Pointers in the src struct.
                blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindHelper;
            }
        }
    }
}

//------------------------------------------------------------------------
// LowerCast: Lower GT_CAST(srcType, DstType) nodes.
//
// Arguments:
//    tree - GT_CAST node to be lowered
//
// Return Value:
//    None.
//
// Notes:
//    Casts from small int type to float/double are transformed as follows:
//    GT_CAST(byte, float/double)     =   GT_CAST(GT_CAST(byte, int32), float/double)
//    GT_CAST(sbyte, float/double)    =   GT_CAST(GT_CAST(sbyte, int32), float/double)
//    GT_CAST(int16, float/double)    =   GT_CAST(GT_CAST(int16, int32), float/double)
//    GT_CAST(uint16, float/double)   =   GT_CAST(GT_CAST(uint16, int32), float/double)
//
//    Similarly casts from float/double to a smaller int type are transformed as follows:
//    GT_CAST(float/double, byte)     =   GT_CAST(GT_CAST(float/double, int32), byte)
//    GT_CAST(float/double, sbyte)    =   GT_CAST(GT_CAST(float/double, int32), sbyte)
//    GT_CAST(float/double, int16)    =   GT_CAST(GT_CAST(double/double, int32), int16)
//    GT_CAST(float/double, uint16)   =   GT_CAST(GT_CAST(double/double, int32), uint16)
//
//    Note that for the overflow conversions we still depend on helper calls and
//    don't expect to see them here.
//    i) GT_CAST(float/double, int type with overflow detection)
//
void Lowering::LowerCast(GenTree* tree)
{
    assert(tree->OperGet() == GT_CAST);

    JITDUMP("LowerCast for: ");
    DISPNODE(tree);
    JITDUMP("\n");

    GenTreePtr op1     = tree->gtOp.gtOp1;
    var_types  dstType = tree->CastToType();
    var_types  srcType = op1->TypeGet();
    var_types  tmpType = TYP_UNDEF;

    if (varTypeIsFloating(srcType))
    {
        noway_assert(!tree->gtOverflow());
    }

    // Case of src is a small type and dst is a floating point type.
    if (varTypeIsSmall(srcType) && varTypeIsFloating(dstType))
    {
        NYI_ARM("Lowering for cast from small type to float"); // Not tested yet.
        // These conversions can never be overflow detecting ones.
        noway_assert(!tree->gtOverflow());
        tmpType = TYP_INT;
    }
    // case of src is a floating point type and dst is a small type.
    else if (varTypeIsFloating(srcType) && varTypeIsSmall(dstType))
    {
        NYI_ARM("Lowering for cast from float to small type"); // Not tested yet.
        tmpType = TYP_INT;
    }

    if (tmpType != TYP_UNDEF)
    {
        GenTreePtr tmp = comp->gtNewCastNode(tmpType, op1, tmpType);
        tmp->gtFlags |= (tree->gtFlags & (GTF_UNSIGNED | GTF_OVERFLOW | GTF_EXCEPT));

        tree->gtFlags &= ~GTF_UNSIGNED;
        tree->gtOp.gtOp1 = tmp;
        BlockRange().InsertAfter(op1, tmp);
    }
}

//------------------------------------------------------------------------
// LowerRotate: Lower GT_ROL and GT_ROL nodes.
//
// Arguments:
//    tree - the node to lower
//
// Return Value:
//    None.
//
void Lowering::LowerRotate(GenTreePtr tree)
{
    if (tree->OperGet() == GT_ROL)
    {
        // There is no ROL instruction on ARM. Convert ROL into ROR.
        GenTreePtr rotatedValue        = tree->gtOp.gtOp1;
        unsigned   rotatedValueBitSize = genTypeSize(rotatedValue->gtType) * 8;
        GenTreePtr rotateLeftIndexNode = tree->gtOp.gtOp2;

        if (rotateLeftIndexNode->IsCnsIntOrI())
        {
            ssize_t rotateLeftIndex                 = rotateLeftIndexNode->gtIntCon.gtIconVal;
            ssize_t rotateRightIndex                = rotatedValueBitSize - rotateLeftIndex;
            rotateLeftIndexNode->gtIntCon.gtIconVal = rotateRightIndex;
        }
        else
        {
            GenTreePtr tmp =
                comp->gtNewOperNode(GT_NEG, genActualType(rotateLeftIndexNode->gtType), rotateLeftIndexNode);
            BlockRange().InsertAfter(rotateLeftIndexNode, tmp);
            tree->gtOp.gtOp2 = tmp;
        }
        tree->ChangeOper(GT_ROR);
    }
}

#endif // _TARGET_ARMARCH_

#endif // !LEGACY_BACKEND