igcse.c

CC386 is a general-purpose 32-bit C compiler. It is not an optimizing compiler but given that the co

            list = list->fwd;
        }
    }
}

//-------------------------------------------------------------------------

static void CalculateAvailable(void)
{
    int i, changed, j;
    for (i = 0; i < blocknum; i++)
        memcpy(blockarray[i]->block->p_aout, blockarray[i]->block->p_agen,
            avail_bytes);
    do
    {
        changed = FALSE;
        for (i = 0; i < blocknum; i++)
        {
            BLOCK *t = blockarray[dfst[i]]->block;
            BLOCKLIST *l = t->flowback;
            if (l)
                memset(t->p_ain, 0xff, avail_bytes);
            while (l)
            {
                for (j = 0; j < avail_bytes; j++)t->p_ain[j] &= l->block
                    ->p_aout[j];
                l = l->link;
            }
            for (j = 0; j < avail_bytes; j++)
            {
                int v = t->p_aout[j];
                t->p_aout[j] = t->p_agen[j] | (t->p_ain[j] &~t->p_akill[j]);
                changed |= (v != t->p_aout[j]);
            }
        }
    }
    while (changed)
        ;

}

//-------------------------------------------------------------------------

static void EnterCSE(QUAD *list)
{
    if (cse_count >= cse_max)
    {
        QUAD **newarray = oalloc(sizeof(QUAD*)*(cse_max += 16));
        if (cse_count)
            memcpy(newarray, csearray, sizeof(QUAD*) * cse_count);
        csearray = newarray;
    }
    csearray[cse_count++] = list;
}

//-------------------------------------------------------------------------

static void GatherCSE(BLOCKLIST *l, QUAD *match)
{
    QUAD *list;
    while (l)
    {
        if (!(l->block->flags &BLOCKLIST_VISITED))
        {
            l->block->flags |= BLOCKLIST_VISITED;
            list = l->block->tail;
            while (list != l->block->head)
            {
                if (!memcmp(match, list, sizeof(struct _basic_dag)))
                    break;
                list = list->back;
            }
            if (list == l->block->head)
            {
                GatherCSE(l->block->flowback, match);
                if (csexit)
                    return ;
            } 
            else
            {
                if (csesize !=  - 1000 && list->ans->size != csesize)
                {
                    csexit = TRUE;
                    return ;
                }
                EnterCSE(list);
                csesize = list->ans->size;
            }
        }
        l = l->link;
    }
}

//-------------------------------------------------------------------------

static void unvisit(void)
{
    int i;
    for (i = 0; i < blocknum; i++)
        blockarray[i]->block->flags = 0;
}

//-------------------------------------------------------------------------

static int ScanForGCSE(BLOCK *l, int index)
{
    int rv = FALSE;
    QUAD *list = l->head;
    QUAD *match = availarray[index];
    BLOCKLIST *s;
    IMODE *im,  *ima;
    QUAD *t;
    LIST *l1;
    int i, ptr, j;
    SYM *sp;
    memcpy(temparray4, l->p_pin, sourcebytes *pointer_count);
    while (1)
    {
        while (list && list->back != l->tail && memcmp(match, list, sizeof
            (struct _basic_dag)))
        {
            switch (list->dc.opcode)
            {
                case i_add:
                case i_sub:
                case i_udiv:
                case i_umod:
                case i_sdiv:
                case i_smod:
                case i_umul:
                case i_smul:
                case i_lsl:
                case i_lsr:
                case i_asl:
                case i_asr:
                case i_neg:
                case i_not:
                case i_and:
                case i_or:
                case i_eor:
                case i_setne:
                case i_sete:
                case i_setc:
                case i_seta:
                case i_setnc:
                case i_setbe:
                case i_setl:
                case i_setg:
                case i_setle:
                case i_setge:
                case i_assn:
                    if (list->ans == match->dc.left || list->ans == match
                        ->dc.right)
                        return rv;
                    // take pointers into account for avail & reaching
                    if (list->ans->mode == i_ind)
                    {
                        BYTE *t4;
                        ptr = findPointer(list->ans);
                        if (ptr < pointer_count)
                        {
                            t4 = temparray4 + ptr * sourcebytes;
                            if (isset(t4, 0))
                            {
                                return rv;
                            }
                            else
                            {
                                for (i = 1; i < source_count; i++)
                                {
                                    if (isset(t4, i))
                                    {
                                        sp = varsp(sourcearray[i]->dc.left
                                            ->offset);
                                        if (sp->imvalue == match->dc.left || sp
                                            ->imvalue == match->dc.right)
                                            return rv;
                                        if (sourcearray[i]->dc.right)
                                        {
                                            sp = sourcearray[i]->dc.right
                                                ->offset;
                                            if (sp->imvalue == match->dc.left 
                                                || sp->imvalue == match
                                                ->dc.right)
                                                return rv;
                                        }
                                    }
                                }
                            }
                        }
                    }
                    else
                    {
                        ptr = findPointer(list->ans);
                        if (ptr < pointer_count)
                        {
                            SYM *sp = varsp(list->ans->offset);
                            if (sp)
                            {
                                l1 = findans(availhash, sp->imind);
                                if (l1)
                                    return rv;
                            }
                        }
                    }
                    break;
                case i_parm:
                    sp = varsp(list->dc.left->offset);
                    if (list->dc.left->mode == i_immed)
                    {
                        if (sp)
                        {
                            if (sp->imvalue == match->dc.left || sp->imvalue ==
                                match->dc.right)
                                return rv;
                        }
                    }
                    else
                    {
                        if (list->dc.left->mode == i_direct)
                        {
                            ptr = findPointer(list->dc.left);
                            if (ptr < pointer_count)
                            {
                                BYTE *t4 = temparray4 + ptr * sourcebytes;
                                if (isset(t4, 0))
                                    return rv;
                                else
                                for (i = 1; i < source_count; i++)
                                {
                                    if (isset(t4, i))
                                    {
                                        sp = varsp(sourcearray[i]->dc.left
                                            ->offset);
                                        if (sp->imvalue == match->dc.left || sp
                                            ->imvalue == match->dc.right)
                                            return rv;
                                        sp = varsp(sourcearray[i]->dc.right
                                            ->offset);
                                        if (sp)
                                            if (sp->imvalue == match->dc.left 
                                                || sp->imvalue == match
                                                ->dc.right)
                                                return rv;
                                    }
                                }
                            }
                        }
                    }
                    break;
                case i_gosub:
                    switch (match->dc.left->offset->nodetype)
                    {
                    case en_nacon:
                    case en_napccon:
                    case en_nalabcon:
                    case en_labcon:
                    case en_absacon:
                        return rv;

                    }
                    switch (match->dc.right->offset->nodetype)
                    {
                    case en_nacon:
                    case en_napccon:
                    case en_nalabcon:
                    case en_labcon:
                    case en_absacon:
                        return rv;

                    }
                    for (i = 0; i < pointer_count; i++)
                    switch (pointerarray[i]->offset->nodetype)
                    {
                    case en_nacon:
                    case en_napccon:
                    case en_nalabcon:
                    case en_labcon:
                    case en_absacon:
                        if (isset(temparray4 + i * sourcebytes, 0))
                            return rv;
                        for (j = 1; j < source_count; j++)
                        {
                            if (sourcearray[j]->dc.left == match->dc.left)
                                return rv;
                            if (sourcearray[j]->dc.left == match->dc.right)
                                return rv;
                            if (sourcearray[j]->dc.right == match->dc.left)
                                return rv;
                            if (sourcearray[j]->dc.right == match->dc.right)
                                return rv;
                        }
                        break;
                    }
                    break;

            }
            ptrindex(list, l, temparray4);
            list = list->fwd;
        }
        if (!list || list->back == l->tail)
            return rv;
        unvisit();
        cse_count = 0;
        csesize =  - 1000;
        csexit = FALSE;
        GatherCSE(l->flowback, match);
        if (cse_count && !csexit)
        {
            rv = TRUE;
            im = 0;
            for (i = 0; i < cse_count; i++)
            {
                sp = varsp(csearray[i]->ans->offset);
                if (!sp->iglobal && sp->storage_class == sc_temp)
                {
                    im = sp->imvalue;
                    break;
                }
            }
            if (!im)
                im = tempreg(csesize, FALSE);
            for (i = 0; i < cse_count; i++)
            {
                if (im != csearray[i]->ans)
                {
                    ima = csearray[i]->ans;
                    csearray[i]->ans = im;
                    t = xalloc(sizeof(QUAD));
                    t->ans = ima;
                    t->dc.left = im;
                    t->dc.opcode = i_assn;
                    t->fwd = csearray[i]->fwd;
                    t->fwd->back = t;
                    t->back = csearray[i];
                    t->back->fwd = t;
                }
            }
            list->dc.left = im;
            list->dc.opcode = i_assn;
            list->dc.right = 0;
        }
        else
            list = list->fwd;
    }
}

//-------------------------------------------------------------------------

void gcse(void)
{
    int i, j;
    int done = FALSE;
    availhash = oalloc(sizeof(LIST3*) * AHASH);
    availhash2 = oalloc(sizeof(LIST3*) * AHASH);
    tempindexarray = oalloc(sizeof(SYM*) * tempnum);
    CountAvail();
    CreateAvailBitArrays();
    while (!done)
    {
        done = TRUE;
        CalculateAvailBasics();
        CalculateAvailable();
        #ifdef DUMP_GCSE_INFO
            dump_avail();
        #endif 
        for (i = 0; i < blocknum; i++)
        {
            BLOCK *l = blockarray[dfst[i]]->block;
            for (j = 0; j < avail_count; j++)
                if (isset(l->p_ain, j))
                    if (ScanForGCSE(l, j))
                        done = FALSE;
        }
    }
}

//-------------------------------------------------------------------------

void gcseRundown(void)
{
    cse_max = cse_count = 0;
}