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[SYCL] Infer IdT in GroupBroadcast from group type #2115

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Merged
merged 2 commits into from
Jul 16, 2020
Merged

[SYCL] Infer IdT in GroupBroadcast from group type #2115

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8e04e65
[SYCL] Infer IdT in GroupBroadcast from group type
Pennycook Jun 10, 2020
8e76a3c
[SYCL] Fix warnings: sub_group is struct not class
Pennycook Jul 14, 2020
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16 changes: 15 additions & 1 deletion sycl/include/CL/sycl/detail/spirv.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -42,15 +42,29 @@ template <typename Group> bool GroupAny(bool pred) {
}

// Broadcast with scalar local index
// Work-group supports any integral type
// Sub-group currently supports only uint32_t
template <typename Group, typename T, typename IdT>
detail::enable_if_t<std::is_integral<IdT>::value, T>
detail::enable_if_t<is_group<Group>::value && std::is_integral<IdT>::value, T>
GroupBroadcast(T x, IdT local_id) {
using OCLT = detail::ConvertToOpenCLType_t<T>;
using OCLIdT = detail::ConvertToOpenCLType_t<IdT>;
OCLT ocl_x = detail::convertDataToType<T, OCLT>(x);
OCLIdT ocl_id = detail::convertDataToType<IdT, OCLIdT>(local_id);
return __spirv_GroupBroadcast(group_scope<Group>::value, ocl_x, ocl_id);
}
template <typename Group, typename T, typename IdT>
detail::enable_if_t<is_sub_group<Group>::value && std::is_integral<IdT>::value,
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@v-klochkov v-klochkov Jul 14, 2020 •
edited
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If IdT is uint64_t, then it will silently truncated to uint32_t, right?
Would it be useful here to assert that local_id fits into 32-bits, or throw an exception if local_id does not fit into 32-bit?

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Truncation is the desired behavior here.

A sub-group's local ID is represented by an id<1> (which is a size_t) but the CPU runtime only accepts a SPIR-V OpGroupBroadcast instruction with Subgroup scope if the LocalId parameter is a uint32_t.

This version of GroupBroadcast can only be called if the Group is a sub-group, so truncating into 32 bits should always be safe.

T>
GroupBroadcast(T x, IdT local_id) {
using SGIdT = uint32_t;
SGIdT sg_local_id = static_cast<SGIdT>(local_id);
using OCLT = detail::ConvertToOpenCLType_t<T>;
using OCLIdT = detail::ConvertToOpenCLType_t<SGIdT>;
OCLT ocl_x = detail::convertDataToType<T, OCLT>(x);
OCLIdT ocl_id = detail::convertDataToType<SGIdT, OCLIdT>(sg_local_id);
return __spirv_GroupBroadcast(group_scope<Group>::value, ocl_x, ocl_id);
}

// Broadcast with vector local index
template <typename Group, typename T, int Dimensions>
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18 changes: 18 additions & 0 deletions sycl/include/CL/sycl/detail/type_traits.hpp
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Expand Up @@ -17,6 +17,10 @@

__SYCL_INLINE_NAMESPACE(cl) {
namespace sycl {
template <int Dimensions> class group;
namespace intel {
struct sub_group;
} // namespace intel
namespace detail {
namespace half_impl {
class half;
Expand Down Expand Up @@ -302,6 +306,20 @@ template <access::address_space AS, class DataT>
using const_if_const_AS = DataT;
#endif

template <typename T> struct is_group : std::false_type {};

template <int Dimensions>
struct is_group<group<Dimensions>> : std::true_type {};

template <typename T> struct is_sub_group : std::false_type {};

template <> struct is_sub_group<intel::sub_group> : std::true_type {};

template <typename T>
struct is_generic_group
: std::integral_constant<bool,
is_group<T>::value || is_sub_group<T>::value> {};

} // namespace detail
} // namespace sycl
} // __SYCL_INLINE_NAMESPACE(cl)
14 changes: 0 additions & 14 deletions sycl/include/CL/sycl/intel/group_algorithm.hpp
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Expand Up @@ -77,20 +77,6 @@ template <> inline id<3> linear_id_to_id(range<3> r, size_t linear_id) {
return result;
}

template <typename T> struct is_group : std::false_type {};

template <int Dimensions>
struct is_group<group<Dimensions>> : std::true_type {};

template <typename T> struct is_sub_group : std::false_type {};

template <> struct is_sub_group<intel::sub_group> : std::true_type {};

template <typename T>
struct is_generic_group
: std::integral_constant<bool,
is_group<T>::value || is_sub_group<T>::value> {};

template <typename T, class BinaryOperation> struct identity {};

template <typename T, typename V> struct identity<T, intel::plus<V>> {
Expand Down