cutlass/include/cutlass/subbyte_reference.h
2022-04-23 15:02:38 -04:00

601 lines
16 KiB
C++

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*
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* list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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/*! \file
\brief Provides a mechanism for packing and unpacking elements smaller than one byte
*/
#pragma once
#include "cutlass/numeric_types.h"
namespace cutlass {
/////////////////////////////////////////////////////////////////////////////////////////////////
/// This class provides a mechanism for packing and unpacking elements smaller than one byte. It
/// assumes these sub-byte elements are packed in a traditional C++ numeric type.
///
/// The intended application is to provide a mechanism to indirectly reference elements in
/// memory or Array<> objects whose addresses cannot otherwise be taken since they are smaller
/// than one byte.
///
/// Supports basic pointer arithmetic:
///
/// Example:
///
/// int4b_t *ptr = ...;
///
/// SubbyteReference<int4b_t> ref = ptr;
/// ref += 15;
///
/// int4b_t x = ref; // load an int4b_t
/// ref = x + 2_s4; // perform arithmetic on int4b_t and then store
///
template <
typename Element_, /// CUTLASS numeric element type.
typename Storage_ = uint8_t /// Underlying storage type. Must be able to hold an integer
/// number of objects of type Element.
>
class ConstSubbyteReference {
public:
using Element = Element_;
using Storage = Storage_;
using StoragePointer = Storage const *;
static_assert(sizeof_bits<Element>::value <= sizeof_bits<Storage>::value,
"Size of Element must not be greater than Storage.");
static_assert(!(sizeof_bits<Storage>::value % sizeof_bits<Element>::value),
"Storage must be divisible by Element");
private:
///! Number of elements per storage vector
int const kElementsPerVector = sizeof_bits<Storage>::value / sizeof_bits<Element>::value;
///! Bit mask
Storage const kMask =
((sizeof_bits<Element>::value < sizeof_bits<Storage>::value) ?
(Storage(1) << sizeof_bits<Element>::value) - Storage(1) :
~Storage(0));
private:
/// Pointer to array containing element
StoragePointer ptr_;
/// Offset (in units of elements) from pointer.
///
/// Invariant: must always be in range [0, kElementsPerVector)
int offset_;
public:
CUTLASS_HOST_DEVICE
ConstSubbyteReference(): ptr_(nullptr), offset_(0) { }
/// Constructor
CUTLASS_HOST_DEVICE
ConstSubbyteReference(
Element const *ptr, /// pointer to memory
int64_t offset /// logical offset in units of Element
):
ptr_(reinterpret_cast<StoragePointer>(ptr)),
offset_(0) {
int64_t offset_in_vectors = offset / kElementsPerVector;
int64_t offset_in_elements = offset % kElementsPerVector;
ptr_ += offset_in_vectors;
offset_ = int(offset_in_elements);
}
/// Constructor
CUTLASS_HOST_DEVICE
ConstSubbyteReference(
Element *ptr = nullptr
): ConstSubbyteReference(ptr, 0) { }
/// Gets storage pointer
CUTLASS_HOST_DEVICE
StoragePointer storage_pointer() const {
return ptr_;
}
/// Gets element offset within storage vector
CUTLASS_HOST_DEVICE
int element_offset() const {
return offset_;
}
/// Unpacks an element from memory
CUTLASS_HOST_DEVICE
Element get() const {
Storage item = Storage((*ptr_ >> (offset_ * sizeof_bits<Element>::value)) & kMask);
return reinterpret_cast<Element const &>(item);
}
/// Unpacks an element from memory
CUTLASS_HOST_DEVICE
operator Element() const {
return get();
}
/// Adds an offset in units of elements to the reference
CUTLASS_HOST_DEVICE
ConstSubbyteReference &operator+=(int offset) {
offset += offset_;
int offset_in_vectors = offset / kElementsPerVector;
int offset_in_elements = offset % kElementsPerVector;
ptr_ += offset_in_vectors;
offset_ = offset_in_elements;
return *this;
}
/// Adds an offset in units of elements to the reference
CUTLASS_HOST_DEVICE
ConstSubbyteReference &operator+=(long long offset) {
offset += offset_;
long long offset_in_vectors = offset / kElementsPerVector;
int offset_in_elements = int(offset % kElementsPerVector);
ptr_ += offset_in_vectors;
offset_ = offset_in_elements;
return *this;
}
/// Adds an offset in units of elements to the reference
CUTLASS_HOST_DEVICE
ConstSubbyteReference &operator-=(int offset) {
int offset_in_vectors = offset / kElementsPerVector;
int offset_in_elements = offset % kElementsPerVector;
ptr_ -= offset_in_vectors;
offset_ -= offset_in_elements;
if (offset_ < 0) {
offset_ += kElementsPerVector;
--ptr_;
}
return *this;
}
/// Adds an offset in units of elements to the reference
CUTLASS_HOST_DEVICE
ConstSubbyteReference &operator-=(long long offset) {
long long offset_in_vectors = offset / kElementsPerVector;
int offset_in_elements = int(offset % kElementsPerVector);
ptr_ -= offset_in_vectors;
offset_ -= offset_in_elements;
if (offset_ < 0) {
offset_ += kElementsPerVector;
--ptr_;
}
return *this;
}
/// Returns a reference to an element with a given offset from the current reference
CUTLASS_HOST_DEVICE
ConstSubbyteReference operator+(int offset) const {
ConstSubbyteReference ref(ptr_, offset_);
ref += offset;
return ref;
}
/// Returns a reference to an element with a given offset from the current reference
CUTLASS_HOST_DEVICE
ConstSubbyteReference operator+(long long offset) const {
ConstSubbyteReference ref(ptr_, offset_);
ref += offset;
return ref;
}
/// Returns a reference to an element with a given offset from the current reference
CUTLASS_HOST_DEVICE
ConstSubbyteReference operator-(int offset) const {
ConstSubbyteReference ref(ptr_, offset_);
ref -= offset;
return ref;
}
/// Returns a reference to an element with a given offset from the current reference
CUTLASS_HOST_DEVICE
ConstSubbyteReference operator-=(long long offset) const {
ConstSubbyteReference ref(ptr_, offset_);
ref -= offset;
return ref;
}
/// Computes the difference in elements between references
CUTLASS_HOST_DEVICE
ptrdiff_t operator-(ConstSubbyteReference ref) const {
return (ptr_ - ref.ptr_) * kElementsPerVector + (offset_ - ref.offset_);
}
/// Explicit cast to int
CUTLASS_HOST_DEVICE
explicit operator int() const {
return int(get());
}
/// Explicit cast to signed 64-bit integer
CUTLASS_HOST_DEVICE
explicit operator int64_t() const {
return int64_t(get());
}
/// Explicit cast to unsigned 64-bit integer
CUTLASS_HOST_DEVICE
explicit operator uint64_t() const {
return uint64_t(get());
}
/// Explicit cast to float
CUTLASS_HOST_DEVICE
explicit operator float() const {
return float(get());
}
/// Explicit cast to double
CUTLASS_HOST_DEVICE
explicit operator double() const {
return double(get());
}
};
template <
typename Element_, /// CUTLASS numeric element type.
typename Storage_ = uint8_t /// Underlying storage type. Must be able to hold an integer
/// number of objects of type Element.
>
class SubbyteReference {
public:
using Element = Element_;
using Storage = Storage_;
using StoragePointer = Storage *;
static_assert(sizeof_bits<Element>::value <= sizeof_bits<Storage>::value,
"Size of Element must not be greater than Storage.");
static_assert(!(sizeof_bits<Storage>::value % sizeof_bits<Element>::value),
"Storage must be divisible by Element");
private:
///! Number of elements per storage vector
int const kElementsPerVector = sizeof_bits<Storage>::value / sizeof_bits<Element>::value;
///! Bit mask
Storage const kMask =
((sizeof_bits<Element>::value < sizeof_bits<Storage>::value) ?
(Storage(1) << sizeof_bits<Element>::value) - Storage(1) :
~Storage(0));
private:
/// Pointer to array containing element
StoragePointer ptr_;
/// Offset (in units of elements) from pointer.
///
/// Invariant: must always be in range [0, kElementsPerVector)
int offset_;
public:
CUTLASS_HOST_DEVICE
SubbyteReference(): ptr_(nullptr), offset_(0) { }
/// Constructor
CUTLASS_HOST_DEVICE
SubbyteReference(
Element *ptr, /// pointer to memory
int64_t offset /// logical offset in units of Element
):
ptr_(reinterpret_cast<StoragePointer>(ptr)),
offset_(0) {
int64_t offset_in_vectors = offset / kElementsPerVector;
int64_t offset_in_elements = offset % kElementsPerVector;
ptr_ += offset_in_vectors;
offset_ = int(offset_in_elements);
}
/// Constructor
CUTLASS_HOST_DEVICE
SubbyteReference(
Element *ptr = nullptr
): SubbyteReference(ptr, 0) { }
/// Gets storage pointer
CUTLASS_HOST_DEVICE
StoragePointer storage_pointer() const {
return ptr_;
}
/// Gets storage pointer
CUTLASS_HOST_DEVICE
Element * operator&() const {
return reinterpret_cast<Element *>(ptr_);
}
/// Gets element offset within storage vector
CUTLASS_HOST_DEVICE
int element_offset() const {
return offset_;
}
/// Unpacks an element from memory
CUTLASS_HOST_DEVICE
Element get() const {
Storage item = Storage((*ptr_ >> (offset_ * sizeof_bits<Element>::value)) & kMask);
return reinterpret_cast<Element const &>(item);
}
/// Stores an element to memory
CUTLASS_HOST_DEVICE
SubbyteReference & set(Element const &x) {
Storage item = (reinterpret_cast<Storage const &>(x) & kMask);
Storage kUpdateMask = Storage(~(kMask << (offset_ * sizeof_bits<Element>::value)));
*ptr_ = Storage((*ptr_ & kUpdateMask) | Storage(item << (offset_ * sizeof_bits<Element>::value)));
return *this;
}
/// Unpacks an element from memory
CUTLASS_HOST_DEVICE
operator Element() const {
return get();
}
/// Stores an element to memory
CUTLASS_HOST_DEVICE
SubbyteReference &operator=(Element const & x) {
return set(x);
}
/// Stores an element to memory
CUTLASS_HOST_DEVICE
SubbyteReference &operator=(SubbyteReference const & x) {
return set(x.get());
}
/// Stores an element to memory
CUTLASS_HOST_DEVICE
SubbyteReference &operator=(
ConstSubbyteReference<Element, Storage> const &x) {
return set(x.get());
}
/// Adds an offset in units of elements to the reference
CUTLASS_HOST_DEVICE
SubbyteReference &operator+=(int offset) {
offset += offset_;
int offset_in_vectors = offset / kElementsPerVector;
int offset_in_elements = offset % kElementsPerVector;
ptr_ += offset_in_vectors;
offset_ = offset_in_elements;
return *this;
}
/// Adds an offset in units of elements to the reference
CUTLASS_HOST_DEVICE
SubbyteReference &operator+=(long long offset) {
offset += offset_;
long long offset_in_vectors = offset / kElementsPerVector;
int offset_in_elements = int(offset % kElementsPerVector);
ptr_ += offset_in_vectors;
offset_ = offset_in_elements;
return *this;
}
/// Adds an offset in units of elements to the reference
CUTLASS_HOST_DEVICE
SubbyteReference &operator-=(int offset) {
int offset_in_vectors = offset / kElementsPerVector;
int offset_in_elements = offset % kElementsPerVector;
ptr_ -= offset_in_vectors;
offset_ -= offset_in_elements;
if (offset_ < 0) {
offset_ += kElementsPerVector;
--ptr_;
}
return *this;
}
/// Adds an offset in units of elements to the reference
CUTLASS_HOST_DEVICE
SubbyteReference &operator-=(long long offset) {
long long offset_in_vectors = offset / kElementsPerVector;
int offset_in_elements = int(offset % kElementsPerVector);
ptr_ -= offset_in_vectors;
offset_ -= offset_in_elements;
if (offset_ < 0) {
offset_ += kElementsPerVector;
--ptr_;
}
return *this;
}
/// Returns a reference to an element with a given offset from the current reference
CUTLASS_HOST_DEVICE
SubbyteReference operator+(int offset) const {
SubbyteReference ref(ptr_, offset_);
ref += offset;
return ref;
}
/// Returns a reference to an element with a given offset from the current reference
CUTLASS_HOST_DEVICE
SubbyteReference operator+(long long offset) const {
SubbyteReference ref(ptr_, offset_);
ref += offset;
return ref;
}
/// Returns a reference to an element with a given offset from the current reference
CUTLASS_HOST_DEVICE
SubbyteReference operator-(int offset) const {
SubbyteReference ref(ptr_, offset_);
ref -= offset;
return ref;
}
/// Returns a reference to an element with a given offset from the current reference
CUTLASS_HOST_DEVICE
SubbyteReference operator-=(long long offset) const {
SubbyteReference ref(ptr_, offset_);
ref -= offset;
return ref;
}
/// Computes the difference in elements between references
CUTLASS_HOST_DEVICE
ptrdiff_t operator-(SubbyteReference ref) const {
return (ptr_ - ref.ptr_) * kElementsPerVector + (offset_ - ref.offset_);
}
/// Explicit cast to int
CUTLASS_HOST_DEVICE
explicit operator int() const {
return int(get());
}
/// Explicit cast to signed 64-bit integer
CUTLASS_HOST_DEVICE
explicit operator int64_t() const {
return int64_t(get());
}
/// Explicit cast to unsigned 64-bit integer
CUTLASS_HOST_DEVICE
explicit operator uint64_t() const {
return uint64_t(get());
}
/// Explicit cast to float
CUTLASS_HOST_DEVICE
explicit operator float() const {
return float(get());
}
/// Explicit cast to double
CUTLASS_HOST_DEVICE
explicit operator double() const {
return double(get());
}
};
/////////////////////////////////////////////////////////////////////////////////////////////////
template <typename Element, bool subbyte = (sizeof_bits<Element>::value < 8)>
struct ReferenceFactory;
template <typename Element>
struct ReferenceFactory<Element, false> {
CUTLASS_HOST_DEVICE
static Element &get(Element *ptr, int64_t offset) {
return ptr[offset];
}
CUTLASS_HOST_DEVICE
static Element const &get(Element const *ptr, int64_t offset) {
return ptr[offset];
}
};
template <typename Element>
struct ReferenceFactory<Element, true> {
CUTLASS_HOST_DEVICE
static SubbyteReference<Element> get(Element *ptr, int64_t offset) {
return SubbyteReference<Element>(ptr, offset);
}
CUTLASS_HOST_DEVICE
static ConstSubbyteReference<Element> get(Element const *ptr,
int64_t offset) {
return ConstSubbyteReference<Element>(ptr, offset);
}
};
/////////////////////////////////////////////////////////////////////////////////////////////////
} // namespace cutlass