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Diffstat (limited to 'absl/base/internal/prefetch.h')
| -rw-r--r-- | absl/base/internal/prefetch.h | 137 |
1 files changed, 0 insertions, 137 deletions
diff --git a/absl/base/internal/prefetch.h b/absl/base/internal/prefetch.h deleted file mode 100644 index aecfd877..00000000 --- a/absl/base/internal/prefetch.h +++ /dev/null @@ -1,137 +0,0 @@ -// Copyright 2022 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// TODO(b/265984188): remove all uses and delete this header. - -#ifndef ABSL_BASE_INTERNAL_PREFETCH_H_ -#define ABSL_BASE_INTERNAL_PREFETCH_H_ - -#include "absl/base/attributes.h" -#include "absl/base/config.h" -#include "absl/base/prefetch.h" - -#ifdef __SSE__ -#include <xmmintrin.h> -#endif - -#if defined(_MSC_VER) && defined(ABSL_INTERNAL_HAVE_SSE) -#include <intrin.h> -#pragma intrinsic(_mm_prefetch) -#endif - -// Compatibility wrappers around __builtin_prefetch, to prefetch data -// for read if supported by the toolchain. - -// Move data into the cache before it is read, or "prefetch" it. -// -// The value of `addr` is the address of the memory to prefetch. If -// the target and compiler support it, data prefetch instructions are -// generated. If the prefetch is done some time before the memory is -// read, it may be in the cache by the time the read occurs. -// -// The function names specify the temporal locality heuristic applied, -// using the names of Intel prefetch instructions: -// -// T0 - high degree of temporal locality; data should be left in as -// many levels of the cache possible -// T1 - moderate degree of temporal locality -// T2 - low degree of temporal locality -// Nta - no temporal locality, data need not be left in the cache -// after the read -// -// Incorrect or gratuitous use of these functions can degrade -// performance, so use them only when representative benchmarks show -// an improvement. -// -// Example usage: -// -// absl::base_internal::PrefetchT0(addr); -// -// Currently, the different prefetch calls behave on some Intel -// architectures as follows: -// -// SNB..SKL SKX -// PrefetchT0() L1/L2/L3 L1/L2 -// PrefetchT1() L2/L3 L2 -// PrefetchT2() L2/L3 L2 -// PrefetchNta() L1/--/L3 L1* -// -// * On SKX PrefetchNta() will bring the line into L1 but will evict -// from L3 cache. This might result in surprising behavior. -// -// SNB = Sandy Bridge, SKL = Skylake, SKX = Skylake Xeon. -// -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace base_internal { - -ABSL_DEPRECATED("Use absl::PrefetchToLocalCache() instead") -inline void PrefetchT0(const void* address) { - absl::PrefetchToLocalCache(address); -} - -ABSL_DEPRECATED("Use absl::PrefetchToLocalCache() instead") -inline void PrefetchNta(const void* address) { - absl::PrefetchToLocalCacheNta(address); -} - -ABSL_DEPRECATED("Use __builtin_prefetch() for advanced prefetch logic instead") -void PrefetchT1(const void* addr); - -ABSL_DEPRECATED("Use __builtin_prefetch() for advanced prefetch logic instead") -void PrefetchT2(const void* addr); - -// Implementation details follow. - -#if ABSL_HAVE_BUILTIN(__builtin_prefetch) || defined(__GNUC__) - -#define ABSL_INTERNAL_HAVE_PREFETCH 1 - -// See __builtin_prefetch: -// https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html. -// -// These functions speculatively load for read only. This is -// safe for all currently supported platforms. However, prefetch for -// store may have problems depending on the target platform. -// -inline void PrefetchT1(const void* addr) { - // Note: this uses prefetcht1 on Intel. - __builtin_prefetch(addr, 0, 2); -} -inline void PrefetchT2(const void* addr) { - // Note: this uses prefetcht2 on Intel. - __builtin_prefetch(addr, 0, 1); -} - -#elif defined(ABSL_INTERNAL_HAVE_SSE) - -#define ABSL_INTERNAL_HAVE_PREFETCH 1 - -inline void PrefetchT1(const void* addr) { - _mm_prefetch(reinterpret_cast<const char*>(addr), _MM_HINT_T1); -} -inline void PrefetchT2(const void* addr) { - _mm_prefetch(reinterpret_cast<const char*>(addr), _MM_HINT_T2); -} - -#else -inline void PrefetchT1(const void*) {} -inline void PrefetchT2(const void*) {} -#endif - -} // namespace base_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_BASE_INTERNAL_PREFETCH_H_ |