abi_ppc64le.cpp

//===-- abi_ppc64le.cpp - Power v2 ABI description ---------------------*- C++ -*-===//
//
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//===----------------------------------------------------------------------===//
//
// The ABI implementation used for 64 bit little-endian PowerPC targets.
//
// The PowerOpen 64bit ELF v2 ABI can be found here:
// https://members.openpowerfoundation.org/document/dl/576
//===----------------------------------------------------------------------===//


struct ABI_PPC64leLayout : AbiLayout {

// count the homogeneous floating aggregate size (saturating at max count of 8)
unsigned isHFA(jl_datatype_t *ty, jl_datatype_t **ty0, bool *hva) const JL_CANSAFEPOINT
{
    if (jl_datatype_size(ty) > 128 || ty->layout->npointers || !ty->layout->flags.isbitsegal || ty->layout->flags.haspadding)
        return 9;

    size_t i, l = ty->layout->nfields;
    // handle homogeneous float aggregates
    if (l == 0) {
        if (ty != jl_float64_type && ty != jl_float32_type)
            return 9;
        *hva = false;
        if (*ty0 == NULL)
            *ty0 = ty;
        else if (*hva || jl_datatype_size(ty) != jl_datatype_size(*ty0))
            return 9;
        return 1;
    }

    // handle homogeneous vector aggregates
    jl_datatype_t *fld0 = (jl_datatype_t*)jl_field_type(ty, 0);
    if (!jl_is_datatype(fld0) || ty->name == jl_vecelement_typename)
        return 9;
    if (fld0->name == jl_vecelement_typename) {
        if (!jl_is_primitivetype(jl_tparam0(fld0)) || jl_datatype_size(ty) > 16)
            return 9;
        if (l != 1 && l != 2 && l != 4 && l != 8 && l != 16)
            return 9;
        *hva = true;
        if (*ty0 == NULL)
            *ty0 = ty;
        else if (!*hva || jl_datatype_size(ty) != jl_datatype_size(*ty0))
            return 9;
        for (i = 1; i < l; i++) {
            jl_datatype_t *fld = (jl_datatype_t*)jl_field_type(ty, i);
            if (fld != fld0)
                return 9;
        }
        return 1;
    }

    // recurse through other struct types
    int n = 0;
    for (i = 0; i < l; i++) {
        jl_datatype_t *fld = (jl_datatype_t*)jl_field_type(ty, i);
        if (!jl_is_datatype(fld) || ((jl_datatype_t*)fld)->layout == NULL || jl_is_layout_opaque(((jl_datatype_t*)fld)->layout))
            return 9;
        n += isHFA((jl_datatype_t*)fld, ty0, hva);
        if (n > 8)
            return 9;
    }
    return n;
}

bool use_sret(jl_datatype_t *dt, LLVMContext &ctx) override JL_CANSAFEPOINT
{
    jl_datatype_t *ty0 = NULL;
    bool hva = false;
    if (jl_datatype_size(dt) > 16 && isHFA(dt, &ty0, &hva) > 8)
        return true;
    return false;
}

bool needPassByRef(jl_datatype_t *dt, AttrBuilder &ab, LLVMContext &ctx, Type *Ty) override JL_CANSAFEPOINT
{
    jl_datatype_t *ty0 = NULL;
    bool hva = false;
    if (jl_datatype_size(dt) > 64 && isHFA(dt, &ty0, &hva) > 8) {
        ab.addByValAttr(Ty);
        return true;
    }
    return false;
}

Type *preferred_llvm_type(jl_datatype_t *dt, bool isret, LLVMContext &ctx) const override JL_CANSAFEPOINT
{
    // Arguments are either scalar or passed by value

    // LLVM passes Float16 in floating-point registers, but this doesn't match the ABI.
    // No C compiler seems to support _Float16 yet, so in the meantime, pass as i16
    if (dt == jl_float16_type || dt == jl_bfloat16_type)
        return Type::getInt16Ty(ctx);

    // don't need to change bitstypes
    if (!jl_datatype_nfields(dt))
        return NULL;
    // legalize this into [n x f32/f64]
    jl_datatype_t *ty0 = NULL;
    bool hva = false;
    int hfa = isHFA(dt, &ty0, &hva);
    if (hfa <= 8) {
        if (ty0 == jl_float32_type) {
            return ArrayType::get(llvm::Type::getFloatTy(ctx), hfa);
        }
        else if (ty0 == jl_float64_type) {
            return ArrayType::get(llvm::Type::getDoubleTy(ctx), hfa);
        }
        else {
            jl_datatype_t *vecty = (jl_datatype_t*)jl_field_type(ty0, 0);
            assert(jl_is_datatype(vecty) && vecty->name == jl_vecelement_typename);
            Type *ety = bitstype_to_llvm(jl_tparam0(vecty), ctx);
            Type *vty = FixedVectorType::get(ety, jl_datatype_nfields(ty0));
            return ArrayType::get(vty, hfa);
        }
    }
    // rewrite integer-sized (non-HFA) struct to an array
    // the bitsize of the integer gives the desired alignment
    size_t size = jl_datatype_size(dt);
    if (size > 8) {
        if (jl_datatype_align(dt) <= 8) {
            Type  *T_int64 = Type::getInt64Ty(ctx);
            return ArrayType::get(T_int64, (size + 7) / 8);
        }
        else {
            Type *T_int128 = Type::getIntNTy(ctx, 128);
            return ArrayType::get(T_int128, (size + 15) / 16);
        }
    }
    return Type::getIntNTy(ctx, size * 8);
}

};