int4 data type (#364)

* Introduce int4 data type.

* Add unit-tests for int4

* Compile int4 UT only when int4 enabled.

* clang-format
Co-authored-by: Adam Osewski <aosewski@amd.com>

CMakeLists.txt

@@ -21,6 +21,14 @@ rocm_setup_version(VERSION 0.2.0)
 include(TargetFlags)
 list(APPEND CMAKE_PREFIX_PATH ${CMAKE_INSTALL_PREFIX} ${CMAKE_INSTALL_PREFIX}/llvm ${CMAKE_INSTALL_PREFIX}/hip /opt/rocm /opt/rocm/llvm /opt/rocm/hip)
 
+option(USE_BITINT_EXTENSION_INT4, "Whether to enable clang's BitInt extension to provide int4 data type." OFF)
+
+if(USE_BITINT_EXTENSION_INT4)
+    add_compile_definitions(CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4)
+    add_compile_options(-Wno-bit-int-extension)
+    message("CK compiled with USE_BITINT_EXTENSION_INT4 set to ${USE_BITINT_EXTENSION_INT4}")
+endif()
+
 ## C++
 enable_language(CXX)
 set(CMAKE_CXX_STANDARD 17)

cmake/googletest.cmake

@@ -42,3 +42,8 @@ target_compile_options(gtest PRIVATE ${GTEST_CMAKE_CXX_FLAGS})
 target_compile_options(gtest_main PRIVATE ${GTEST_CMAKE_CXX_FLAGS})
 target_compile_options(gmock PRIVATE ${GTEST_CMAKE_CXX_FLAGS})
 target_compile_options(gmock_main PRIVATE ${GTEST_CMAKE_CXX_FLAGS})
+
+set_target_properties(gtest PROPERTIES POSITION_INDEPENDENT_CODE ON)
+set_target_properties(gtest_main PROPERTIES POSITION_INDEPENDENT_CODE ON)
+set_target_properties(gmock PROPERTIES POSITION_INDEPENDENT_CODE ON)
+set_target_properties(gmock_main PROPERTIES POSITION_INDEPENDENT_CODE ON)

include/ck/tensor_operation/gpu/element/unary_element_wise_operation.hpp

@@ -62,6 +62,14 @@ struct PassThrough
     {
         y = type_convert<int8_t>(x);
     }
+
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+    template <>
+    __host__ __device__ void operator()<int4_t, int4_t>(int4_t& y, const int4_t& x) const
+    {
+        y = x;
+    }
+#endif
 };
 
 struct UnaryConvert
@@ -111,9 +119,13 @@ struct UnarySquare
     template <typename T>
     __host__ __device__ void operator()(T& y, const T& x) const
     {
-        static_assert(is_same<T, float>::value || is_same<T, double>::value,
+        static_assert(is_same_v<T, float> || is_same_v<T, double> || is_same_v<T, int32_t> ||
+                          is_same_v<T, int8_t>
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+                          || is_same_v<T, int4_t>
+#endif
+                      ,
                       "Data type is not supported by this operation!");
-
         y = x * x;
     };
 };

include/ck/utility/data_type.hpp

@@ -9,6 +9,9 @@ namespace ck {
 
 using bhalf_t = ushort;
 using half_t  = _Float16;
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+using int4_t = _BitInt(4);
+#endif
 
 // vector_type
 template <typename T, index_t N>
@@ -130,6 +133,15 @@ struct scalar_type<int8_t>
     static constexpr index_t vector_size = 1;
 };
 
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+template <>
+struct scalar_type<int4_t>
+{
+    using type                           = int4_t;
+    static constexpr index_t vector_size = 1;
+};
+#endif
+
 //
 template <typename T>
 struct vector_type<T, 1>
@@ -1030,4 +1042,16 @@ struct NumericLimits<half_t>
     __host__ __device__ static constexpr half_t QuietNaN() { return bit_cast<half_t>(binary_qnan); }
 };
 
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+template <>
+struct NumericLimits<int4_t>
+{
+    __host__ __device__ static constexpr int4_t Min() { return int4_t(-7); }
+
+    __host__ __device__ static constexpr int4_t Max() { return int4_t(7); }
+
+    __host__ __device__ static constexpr int4_t Lowest() { return int4_t(-7); }
+};
+#endif // CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+
 } // namespace ck

include/ck/utility/math_v2.hpp

@@ -42,6 +42,14 @@ static inline __host__ half_t abs(half_t x)
     return abs_x;
 };
 
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+static inline __host__ int4_t abs(int4_t x)
+{
+    int4_t sgn = x >> (4 - 1);
+    return (x ^ sgn) - sgn;
+}
+#endif
+
 static inline __host__ bool isnan(float x) { return std::isnan(x); };
 
 static inline __host__ bool isnan(double x) { return std::isnan(x); };
@@ -65,6 +73,14 @@ static inline __host__ bool isnan(half_t x)
     return (xx & 0x7FFF) > 0x7C00;
 };
 
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+static inline __host__ bool isnan(int4_t x)
+{
+    (void)x;
+    return false;
+};
+#endif
+
 static inline __host__ float sqrt(float x) { return std::sqrt(x); };
 
 static inline __host__ double sqrt(double x) { return std::sqrt(x); };
@@ -89,6 +105,15 @@ static inline __device__ int32_t abs(int32_t x)
     return (x ^ sgn) - sgn;
 };
 
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+static inline __device__ int4_t abs(int4_t x)
+{
+    int4_t sgn = x >> (4 - 1);
+
+    return (x ^ sgn) - sgn;
+};
+#endif
+
 static inline __device__ half_t abs(half_t x) { return ::__habs(x); };
 
 static inline __device__ bool isnan(float x) { return ::isnan(x); };
@@ -107,6 +132,14 @@ static inline __device__ bool isnan(int32_t x)
     return false;
 };
 
+#ifdef CK_EXPERIMENTAL_BIT_INT_EXTENSION_INT4
+static inline __device__ bool isnan(int4_t x)
+{
+    (void)x;
+    return false;
+};
+#endif
+
 static inline __device__ bool isnan(half_t x) { return ::__hisnan(x); };
 
 static inline __device__ float sqrt(float x) { return ::sqrtf(x); };

test/CMakeLists.txt

@@ -51,3 +51,4 @@ add_subdirectory(grouped_convnd_fwd)
 add_subdirectory(block_to_ctile_map)
 add_subdirectory(softmax)
 add_subdirectory(layernorm)
+add_subdirectory(data_type)

test/data_type/CMakeLists.txt

+if (USE_BITINT_EXTENSION_INT4)
+  add_gtest_executable(test_int4 int4.cpp)
+  target_link_libraries(test_int4 PRIVATE utility)
+endif()

test/data_type/int4.cpp

+// SPDX-License-Identifier: MIT
+// Copyright (c) 2018-2022, Advanced Micro Devices, Inc. All rights reserved.
+
+#include "gtest/gtest.h"
+
+#include "ck/utility/data_type.hpp"
+#include "ck/utility/math_v2.hpp"
+
+using ck::int4_t;
+
+TEST(Int4, BaseArithmetic)
+{
+    int4_t a{1};
+    int4_t b{-2};
+    EXPECT_EQ(a + a, int4_t{2});
+    EXPECT_EQ(a - a, int4_t{0});
+    EXPECT_EQ(a + b, int4_t{-1});
+    EXPECT_EQ(a - b, int4_t{3});
+    EXPECT_EQ(a * a, int4_t{1});
+    EXPECT_EQ(a * b, int4_t{-2});
+    EXPECT_EQ(b * b, int4_t{4});
+    EXPECT_EQ(a / b, int4_t{0});
+    a = int4_t{4};
+    EXPECT_EQ(a / b, int4_t{-2});
+    b = int4_t{2};
+    EXPECT_EQ(a % b, int4_t{0});
+}
+
+TEST(Int4, NumericLimits)
+{
+    EXPECT_EQ(ck::NumericLimits<int4_t>::Min(), int4_t{-7});
+    EXPECT_EQ(ck::NumericLimits<int4_t>::Max(), int4_t{7});
+    EXPECT_EQ(ck::NumericLimits<int4_t>::Lowest(), int4_t{-7});
+}
+
+TEST(Int4, MathOpsV2)
+{
+    int4_t a{4};
+    int4_t b{-5};
+
+    EXPECT_EQ(ck::math::abs(a), int4_t{4});
+    EXPECT_EQ(ck::math::abs(b), int4_t{5});
+    EXPECT_FALSE(ck::math::isnan(b));
+}