C++ BaseClass::fillVtbl方法代码示例

unsigned ClassDeclaration::baseVtblOffset(BaseClass *bc)
{
    unsigned csymoffset;

    //printf("ClassDeclaration::baseVtblOffset('%s', bc = %p)\n", toChars(), bc);
    csymoffset = global.params.isLP64 ? CLASSINFO_SIZE_64 : CLASSINFO_SIZE;    // must be ClassInfo.size
    csymoffset += vtblInterfaces->dim * (4 * Target::ptrsize);

    for (size_t i = 0; i < vtblInterfaces->dim; i++)
    {
        BaseClass *b = (*vtblInterfaces)[i];

        if (b == bc)
            return csymoffset;
        csymoffset += b->base->vtbl.dim * Target::ptrsize;
    }

    // Put out the overriding interface vtbl[]s.
    // This must be mirrored with ClassDeclaration::baseVtblOffset()
    //printf("putting out overriding interface vtbl[]s for '%s' at offset x%x\n", toChars(), offset);
    ClassDeclaration *cd;
    FuncDeclarations bvtbl;

    for (cd = this->baseClass; cd; cd = cd->baseClass)
    {
        for (size_t k = 0; k < cd->vtblInterfaces->dim; k++)
        {   BaseClass *bs = (*cd->vtblInterfaces)[k];

            if (bs->fillVtbl(this, NULL, 0))
            {
                if (bc == bs)
                {   //printf("\tcsymoffset = x%x\n", csymoffset);
                    return csymoffset;
                }
                csymoffset += bs->base->vtbl.dim * Target::ptrsize;
            }
        }
    }

    return ~0;
}

unsigned baseVtblOffset(ClassDeclaration *cd, BaseClass *bc)
{
    //printf("ClassDeclaration::baseVtblOffset('%s', bc = %p)\n", cd->toChars(), bc);
    unsigned csymoffset = Target::classinfosize;    // must be ClassInfo.size
    csymoffset += cd->vtblInterfaces->dim * (4 * Target::ptrsize);

    for (size_t i = 0; i < cd->vtblInterfaces->dim; i++)
    {
        BaseClass *b = (*cd->vtblInterfaces)[i];

        if (b == bc)
            return csymoffset;
        csymoffset += b->sym->vtbl.dim * Target::ptrsize;
    }

    // Put out the overriding interface vtbl[]s.
    // This must be mirrored with ClassDeclaration::baseVtblOffset()
    //printf("putting out overriding interface vtbl[]s for '%s' at offset x%x\n", toChars(), offset);
    ClassDeclaration *cd2;

    for (cd2 = cd->baseClass; cd2; cd2 = cd2->baseClass)
    {
        for (size_t k = 0; k < cd2->vtblInterfaces->dim; k++)
        {
            BaseClass *bs = (*cd2->vtblInterfaces)[k];
            if (bs->fillVtbl(cd, NULL, 0))
            {
                if (bc == bs)
                {
                    //printf("\tcsymoffset = x%x\n", csymoffset);
                    return csymoffset;
                }
                csymoffset += bs->sym->vtbl.dim * Target::ptrsize;
            }
        }
    }

    return ~0;
}

//.........这里部分代码省略.........
                dtsize_t(&dt, 0);

            // xgetRTInfo
            if (cd->getRTInfo)
                Expression_toDt(cd->getRTInfo, &dt);
            else if (flags & ClassFlags::noPointers)
                dtsize_t(&dt, 0);
            else
                dtsize_t(&dt, 1);

            //dtxoff(&dt, toSymbol(type->vtinfo), 0, TYnptr); // typeinfo

            //////////////////////////////////////////////

            // Put out (*vtblInterfaces)[]. Must immediately follow csym, because
            // of the fixup (*)

            offset += cd->vtblInterfaces->dim * (4 * Target::ptrsize);
            for (size_t i = 0; i < cd->vtblInterfaces->dim; i++)
            {
                BaseClass *b = (*cd->vtblInterfaces)[i];
                ClassDeclaration *id = b->sym;

                /* The layout is:
                 *  struct Interface
                 *  {
                 *      ClassInfo *interface;
                 *      void *[] vtbl;
                 *      size_t offset;
                 *  }
                 */

                // Fill in vtbl[]
                b->fillVtbl(cd, &b->vtbl, 1);

                dtxoff(&dt, toSymbol(id), 0, TYnptr);         // ClassInfo

                // vtbl[]
                dtsize_t(&dt, id->vtbl.dim);
                dtxoff(&dt, cd->csym, offset, TYnptr);

                dtsize_t(&dt, b->offset);                        // this offset

                offset += id->vtbl.dim * Target::ptrsize;
            }

            // Put out the (*vtblInterfaces)[].vtbl[]
            // This must be mirrored with ClassDeclaration::baseVtblOffset()
            //printf("putting out %d interface vtbl[]s for '%s'\n", vtblInterfaces->dim, toChars());
            for (size_t i = 0; i < cd->vtblInterfaces->dim; i++)
            {
                BaseClass *b = (*cd->vtblInterfaces)[i];
                ClassDeclaration *id = b->sym;

                //printf("    interface[%d] is '%s'\n", i, id->toChars());
                size_t j = 0;
                if (id->vtblOffset())
                {
                    // First entry is ClassInfo reference
                    //dtxoff(&dt, toSymbol(id), 0, TYnptr);

                    // First entry is struct Interface reference
                    dtxoff(&dt, cd->csym, Target::classinfosize + i * (4 * Target::ptrsize), TYnptr);
                    j = 1;
                }
                assert(id->vtbl.dim == b->vtbl.dim);

//.........这里部分代码省略.........
                if (v_begin >= f_end || v_end <= f_begin)
                    continue;

                overlaps = true;
                break;
            }
        }

        // if no overlap was found, add the default initializer
        if (!overlaps)
        {
            IF_LOG Logger::println("adding default initializer for struct field %s",
                field_it->toChars());
            data[field_it.index] = *field_it;
        }
    }

    // ok. now we can build a list of llvm types. and make sure zeros are inserted if necessary.

    // first we sort the list by offset
    std::sort(data.begin(), data.end(), var_offset_sort_cb);

    // add types to list
    for (size_t i = 0; i < n; i++)
    {
        VarDeclaration* vd = data[i];

        if (vd == NULL)
            continue;

        assert(vd->offset >= offset && "it's a bug... most likely DMD bug 2481");

        // add to default field list
        if (cd == base)
            default_fields.push_back(vd);

        // get next aligned offset for this type
        size_t alignedoffset = realignOffset(offset, vd->type);

        // insert explicit padding?
        if (alignedoffset < vd->offset)
        {
            field_index += add_zeros(defaultTypes, vd->offset - alignedoffset);
        }

        // add default type
        defaultTypes.push_back(DtoType(vd->type));

        // advance offset to right past this field
        offset = vd->offset + vd->type->size();

        // create ir field
        vd->aggrIndex = (unsigned)field_index;
        ++field_index;
    }

    // any interface implementations?
    if (base->vtblInterfaces && base->vtblInterfaces->dim > 0)
    {
        bool new_instances = (base == cd);

        ArrayIter<BaseClass> it2(*base->vtblInterfaces);

        VarDeclarationIter interfaces_idx(ClassDeclaration::classinfo->fields, 3);
	Type* first = interfaces_idx->type->nextOf()->pointerTo();

        // align offset
        offset = (offset + PTRSIZE - 1) & ~(PTRSIZE - 1);

        for (; !it2.done(); it2.next())
        {
            BaseClass* b = it2.get();
            IF_LOG Logger::println("Adding interface vtbl for %s", b->base->toPrettyChars());

            FuncDeclarations arr;
            b->fillVtbl(cd, &arr, new_instances);

            llvm::Type* ivtbl_type = llvm::StructType::get(gIR->context(), buildVtblType(first, &arr));
            defaultTypes.push_back(llvm::PointerType::get(ivtbl_type, 0));

            offset += PTRSIZE;

            // add to the interface map
            addInterfaceToMap(b->base, field_index);
            field_index++;

            // inc count
            num_interface_vtbls++;
        }
    }

#if 0
    // tail padding?
    if (offset < base->structsize)
    {
        field_index += add_zeros(defaultTypes, base->structsize - offset);
        offset = base->structsize;
    }
#endif
}