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//===-- gpuintrin.h - Generic GPU intrinsic functions ---------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Provides wrappers around the clang builtins for accessing GPU hardware
// features. The interface is intended to be portable between architectures, but
// some targets may provide different implementations. This header can be
// included for all the common GPU programming languages, namely OpenMP, HIP,
// CUDA, and OpenCL.
//
//===----------------------------------------------------------------------===//
#ifndef __GPUINTRIN_H
#define __GPUINTRIN_H
#if !defined(_DEFAULT_FN_ATTRS)
#if defined(__HIP__) || defined(__CUDA__)
#define _DEFAULT_FN_ATTRS __attribute__((device))
#else
#define _DEFAULT_FN_ATTRS
#endif
#endif
#include <stdint.h>
#if !defined(__cplusplus)
_Pragma("push_macro(\"bool\")");
#define bool _Bool
#endif
_Pragma("omp begin declare target device_type(nohost)");
_Pragma("omp begin declare variant match(device = {kind(gpu)})");
// Forward declare a few functions for the implementation header.
// Returns a bitmask marking all lanes that have the same value of __x.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_match_any_u32_impl(uint64_t __lane_mask, uint32_t __x);
// Returns a bitmask marking all lanes that have the same value of __x.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_match_any_u64_impl(uint64_t __lane_mask, uint64_t __x);
// Returns the current lane mask if every lane contains __x.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_match_all_u32_impl(uint64_t __lane_mask, uint32_t __x);
// Returns the current lane mask if every lane contains __x.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_match_all_u64_impl(uint64_t __lane_mask, uint64_t __x);
_Pragma("omp end declare variant");
_Pragma("omp end declare target");
#if defined(__NVPTX__)
#include <nvptxintrin.h>
#elif defined(__AMDGPU__)
#include <amdgpuintrin.h>
#elif !defined(_OPENMP)
#error "This header is only meant to be used on GPU architectures."
#endif
_Pragma("omp begin declare target device_type(nohost)");
_Pragma("omp begin declare variant match(device = {kind(gpu)})");
#define __GPU_X_DIM 0
#define __GPU_Y_DIM 1
#define __GPU_Z_DIM 2
// Returns the number of blocks in the requested dimension.
_DEFAULT_FN_ATTRS static __inline__ uint32_t __gpu_num_blocks(int __dim) {
switch (__dim) {
case 0:
return __gpu_num_blocks_x();
case 1:
return __gpu_num_blocks_y();
case 2:
return __gpu_num_blocks_z();
default:
__builtin_unreachable();
}
}
// Returns the number of block id in the requested dimension.
_DEFAULT_FN_ATTRS static __inline__ uint32_t __gpu_block_id(int __dim) {
switch (__dim) {
case 0:
return __gpu_block_id_x();
case 1:
return __gpu_block_id_y();
case 2:
return __gpu_block_id_z();
default:
__builtin_unreachable();
}
}
// Returns the number of threads in the requested dimension.
_DEFAULT_FN_ATTRS static __inline__ uint32_t __gpu_num_threads(int __dim) {
switch (__dim) {
case 0:
return __gpu_num_threads_x();
case 1:
return __gpu_num_threads_y();
case 2:
return __gpu_num_threads_z();
default:
__builtin_unreachable();
}
}
// Returns the thread id in the requested dimension.
_DEFAULT_FN_ATTRS static __inline__ uint32_t __gpu_thread_id(int __dim) {
switch (__dim) {
case 0:
return __gpu_thread_id_x();
case 1:
return __gpu_thread_id_y();
case 2:
return __gpu_thread_id_z();
default:
__builtin_unreachable();
}
}
// Get the first active thread inside the lane.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_first_lane_id(uint64_t __lane_mask) {
return __builtin_ffsll(__lane_mask) - 1;
}
// Conditional that is only true for a single thread in a lane.
_DEFAULT_FN_ATTRS static __inline__ bool
__gpu_is_first_in_lane(uint64_t __lane_mask) {
return __gpu_lane_id() == __gpu_first_lane_id(__lane_mask);
}
// Copies the value from the first active thread to the rest.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_read_first_lane_u64(uint64_t __lane_mask, uint64_t __x) {
uint32_t __hi = (uint32_t)(__x >> 32ull);
uint32_t __lo = (uint32_t)(__x & 0xFFFFFFFFull);
return ((uint64_t)__gpu_read_first_lane_u32(__lane_mask, __hi) << 32ull) |
((uint64_t)__gpu_read_first_lane_u32(__lane_mask, __lo) &
0xFFFFFFFFull);
}
// Gets the first floating point value from the active lanes.
_DEFAULT_FN_ATTRS static __inline__ float
__gpu_read_first_lane_f32(uint64_t __lane_mask, float __x) {
return __builtin_bit_cast(
float, __gpu_read_first_lane_u32(__lane_mask,
__builtin_bit_cast(uint32_t, __x)));
}
// Gets the first floating point value from the active lanes.
_DEFAULT_FN_ATTRS static __inline__ double
__gpu_read_first_lane_f64(uint64_t __lane_mask, double __x) {
return __builtin_bit_cast(
double, __gpu_read_first_lane_u64(__lane_mask,
__builtin_bit_cast(uint64_t, __x)));
}
// Shuffles the the lanes according to the given index.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_shuffle_idx_u64(uint64_t __lane_mask, uint32_t __idx, uint64_t __x,
uint32_t __width) {
uint32_t __hi = (uint32_t)(__x >> 32ull);
uint32_t __lo = (uint32_t)(__x & 0xFFFFFFFF);
uint32_t __mask = (uint32_t)__lane_mask;
return ((uint64_t)__gpu_shuffle_idx_u32(__mask, __idx, __hi, __width)
<< 32ull) |
((uint64_t)__gpu_shuffle_idx_u32(__mask, __idx, __lo, __width));
}
// Shuffles the the lanes according to the given index.
_DEFAULT_FN_ATTRS static __inline__ float
__gpu_shuffle_idx_f32(uint64_t __lane_mask, uint32_t __idx, float __x,
uint32_t __width) {
return __builtin_bit_cast(
float, __gpu_shuffle_idx_u32(__lane_mask, __idx,
__builtin_bit_cast(uint32_t, __x), __width));
}
// Shuffles the the lanes according to the given index.
_DEFAULT_FN_ATTRS static __inline__ double
__gpu_shuffle_idx_f64(uint64_t __lane_mask, uint32_t __idx, double __x,
uint32_t __width) {
return __builtin_bit_cast(
double,
__gpu_shuffle_idx_u64(__lane_mask, __idx,
__builtin_bit_cast(uint64_t, __x), __width));
}
// Gets the accumulator scan of the threads in the warp or wavefront.
#define __DO_LANE_SCAN(__type, __bitmask_type, __suffix) \
_DEFAULT_FN_ATTRS static __inline__ uint32_t __gpu_lane_scan_##__suffix( \
uint64_t __lane_mask, uint32_t __x) { \
uint64_t __first = __lane_mask >> __builtin_ctzll(__lane_mask); \
bool __divergent = __gpu_read_first_lane_##__suffix( \
__lane_mask, __first & (__first + 1)); \
if (__divergent) { \
__type __accum = 0; \
for (uint64_t __mask = __lane_mask; __mask; __mask &= __mask - 1) { \
__type __index = __builtin_ctzll(__mask); \
__type __tmp = __gpu_shuffle_idx_##__suffix(__lane_mask, __index, __x, \
__gpu_num_lanes()); \
__x = __gpu_lane_id() == __index ? __accum + __tmp : __x; \
__accum += __tmp; \
} \
} else { \
for (uint32_t __step = 1; __step < __gpu_num_lanes(); __step *= 2) { \
uint32_t __index = __gpu_lane_id() - __step; \
__bitmask_type bitmask = __gpu_lane_id() >= __step; \
__x += __builtin_bit_cast( \
__type, \
-bitmask & __builtin_bit_cast(__bitmask_type, \
__gpu_shuffle_idx_##__suffix( \
__lane_mask, __index, __x, \
__gpu_num_lanes()))); \
} \
} \
return __x; \
}
__DO_LANE_SCAN(uint32_t, uint32_t, u32); // uint32_t __gpu_lane_scan_u32(m, x)
__DO_LANE_SCAN(uint64_t, uint64_t, u64); // uint64_t __gpu_lane_scan_u64(m, x)
__DO_LANE_SCAN(float, uint32_t, f32); // float __gpu_lane_scan_f32(m, x)
__DO_LANE_SCAN(double, uint64_t, f64); // double __gpu_lane_scan_f64(m, x)
#undef __DO_LANE_SCAN
// Gets the sum of all lanes inside the warp or wavefront.
#define __DO_LANE_SUM(__type, __suffix) \
_DEFAULT_FN_ATTRS static __inline__ __type __gpu_lane_sum_##__suffix( \
uint64_t __lane_mask, __type __x) { \
uint64_t __first = __lane_mask >> __builtin_ctzll(__lane_mask); \
bool __divergent = __gpu_read_first_lane_##__suffix( \
__lane_mask, __first & (__first + 1)); \
if (__divergent) { \
return __gpu_shuffle_idx_##__suffix( \
__lane_mask, 63 - __builtin_clzll(__lane_mask), \
__gpu_lane_scan_##__suffix(__lane_mask, __x), __gpu_num_lanes()); \
} else { \
for (uint32_t __step = 1; __step < __gpu_num_lanes(); __step *= 2) { \
uint32_t __index = __step + __gpu_lane_id(); \
__x += __gpu_shuffle_idx_##__suffix(__lane_mask, __index, __x, \
__gpu_num_lanes()); \
} \
return __gpu_read_first_lane_##__suffix(__lane_mask, __x); \
} \
}
__DO_LANE_SUM(uint32_t, u32); // uint32_t __gpu_lane_sum_u32(m, x)
__DO_LANE_SUM(uint64_t, u64); // uint64_t __gpu_lane_sum_u64(m, x)
__DO_LANE_SUM(float, f32); // float __gpu_lane_sum_f32(m, x)
__DO_LANE_SUM(double, f64); // double __gpu_lane_sum_f64(m, x)
#undef __DO_LANE_SUM
// Returns a bitmask marking all lanes that have the same value of __x.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_match_any_u32_impl(uint64_t __lane_mask, uint32_t __x) {
uint64_t __match_mask = 0;
bool __done = 0;
while (__gpu_ballot(__lane_mask, !__done)) {
if (!__done) {
uint32_t __first = __gpu_read_first_lane_u32(__lane_mask, __x);
if (__first == __x) {
__match_mask = __gpu_lane_mask();
__done = 1;
}
}
}
__gpu_sync_lane(__lane_mask);
return __match_mask;
}
// Returns a bitmask marking all lanes that have the same value of __x.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_match_any_u64_impl(uint64_t __lane_mask, uint64_t __x) {
uint64_t __match_mask = 0;
bool __done = 0;
while (__gpu_ballot(__lane_mask, !__done)) {
if (!__done) {
uint64_t __first = __gpu_read_first_lane_u64(__lane_mask, __x);
if (__first == __x) {
__match_mask = __gpu_lane_mask();
__done = 1;
}
}
}
__gpu_sync_lane(__lane_mask);
return __match_mask;
}
// Returns the current lane mask if every lane contains __x.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_match_all_u32_impl(uint64_t __lane_mask, uint32_t __x) {
uint32_t __first = __gpu_read_first_lane_u32(__lane_mask, __x);
uint64_t __ballot = __gpu_ballot(__lane_mask, __x == __first);
__gpu_sync_lane(__lane_mask);
return __ballot == __gpu_lane_mask() ? __gpu_lane_mask() : 0ull;
}
// Returns the current lane mask if every lane contains __x.
_DEFAULT_FN_ATTRS static __inline__ uint64_t
__gpu_match_all_u64_impl(uint64_t __lane_mask, uint64_t __x) {
uint64_t __first = __gpu_read_first_lane_u64(__lane_mask, __x);
uint64_t __ballot = __gpu_ballot(__lane_mask, __x == __first);
__gpu_sync_lane(__lane_mask);
return __ballot == __gpu_lane_mask() ? __gpu_lane_mask() : 0ull;
}
_Pragma("omp end declare variant");
_Pragma("omp end declare target");
#if !defined(__cplusplus)
_Pragma("pop_macro(\"bool\")");
#endif
#undef _DEFAULT_FN_ATTRS
#endif // __GPUINTRIN_H