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authorGravatar Abseil Team <absl-team@google.com>2019-04-16 12:11:35 -0700
committerGravatar Alex Strelnikov <strel@google.com>2019-04-16 15:40:40 -0400
commitd902eb869bcfacc1bad14933ed9af4bed006d481 (patch)
tree2c6b4c121bb5a696657d63db03a166404b3592b8 /absl/base/internal/unaligned_access.h
parenta02f62f456f2c4a7ecf2be3104fe0c6e16fbad9a (diff)
Export of internal Abseil changes.
-- babbb6421068af3831870fd5995444437ace6769 by Derek Mauro <dmauro@google.com>: Rollback of: Make raw_hash_set_test less flaky. Split the timing loop into chunks so that we are less suceptible to antogantistic processes. PiperOrigin-RevId: 243854490 -- a2711f17a712f6d09799bf32363d67526737b486 by CJ Johnson <johnsoncj@google.com>: Relocates IsAtLeastForwardIterator to internal/inlined_vector.h PiperOrigin-RevId: 243846090 -- 6c14cdbeb9a61022c27f8957654f930d8abf2fc1 by Matt Kulukundis <kfm@google.com>: Make raw_hash_set_test less flaky. Split the timing loop into chunks so that we are less suceptible to antogantistic processes. PiperOrigin-RevId: 243824289 -- ee6072a6b6e0ac653622524ceb09db3b9e870f96 by Samuel Benzaquen <sbenza@google.com>: Improve format parser performance. Replace the main switch with a lookup in the existing tag table. Improve the ABI of ConsumeUnboundConversion a little. PiperOrigin-RevId: 243824112 -- 24b9e6476dfa4be8d644359eab8ac6816492f187 by Abseil Team <absl-team@google.com>: Fix DR numbers: 3800 ? 3080, 3801 ? 3081. PiperOrigin-RevId: 243804213 -- 0660404074707e197684f07cc0bffe4a9c35cd2f by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 243757359 -- ba0f5bb9b8584d75c4ffc44ff3cb8c691796ffc6 by Xiaoyi Zhang <zhangxy@google.com>: Consolidate ABSL_INTERNAL_UNALIGNED_* implementation into memcpy. The compiler should be good enough to optimize these operations. See https://github.com/abseil/abseil-cpp/issues/269 for background. PiperOrigin-RevId: 243323941 -- 00853a8756548df7217513c562d604b4ee5c6ab9 by Eric Fiselier <ericwf@google.com>: Reexport memory.h from optional.h for compatibility between libc++ and libstdc++. PiperOrigin-RevId: 243313425 GitOrigin-RevId: babbb6421068af3831870fd5995444437ace6769 Change-Id: Ic53c127ad857a431ad60c98b27cc585fed50a3e3
Diffstat (limited to 'absl/base/internal/unaligned_access.h')
-rw-r--r--absl/base/internal/unaligned_access.h165
1 files changed, 0 insertions, 165 deletions
diff --git a/absl/base/internal/unaligned_access.h b/absl/base/internal/unaligned_access.h
index 2d667377..2cf7c1d4 100644
--- a/absl/base/internal/unaligned_access.h
+++ b/absl/base/internal/unaligned_access.h
@@ -25,15 +25,6 @@
// unaligned APIs
// Portable handling of unaligned loads, stores, and copies.
-// On some platforms, like ARM, the copy functions can be more efficient
-// then a load and a store.
-//
-// It is possible to implement all of these these using constant-length memcpy
-// calls, which is portable and will usually be inlined into simple loads and
-// stores if the architecture supports it. However, such inlining usually
-// happens in a pass that's quite late in compilation, which means the resulting
-// loads and stores cannot participate in many other optimizations, leading to
-// overall worse code.
// The unaligned API is C++ only. The declarations use C++ features
// (namespaces, inline) which are absent or incompatible in C.
@@ -108,164 +99,8 @@ inline void UnalignedStore64(void *p, uint64_t v) {
#define ABSL_INTERNAL_UNALIGNED_STORE64(_p, _val) \
(absl::base_internal::UnalignedStore64(_p, _val))
-#elif defined(UNDEFINED_BEHAVIOR_SANITIZER)
-
-namespace absl {
-namespace base_internal {
-
-inline uint16_t UnalignedLoad16(const void *p) {
- uint16_t t;
- memcpy(&t, p, sizeof t);
- return t;
-}
-
-inline uint32_t UnalignedLoad32(const void *p) {
- uint32_t t;
- memcpy(&t, p, sizeof t);
- return t;
-}
-
-inline uint64_t UnalignedLoad64(const void *p) {
- uint64_t t;
- memcpy(&t, p, sizeof t);
- return t;
-}
-
-inline void UnalignedStore16(void *p, uint16_t v) { memcpy(p, &v, sizeof v); }
-
-inline void UnalignedStore32(void *p, uint32_t v) { memcpy(p, &v, sizeof v); }
-
-inline void UnalignedStore64(void *p, uint64_t v) { memcpy(p, &v, sizeof v); }
-
-} // namespace base_internal
-} // namespace absl
-
-#define ABSL_INTERNAL_UNALIGNED_LOAD16(_p) \
- (absl::base_internal::UnalignedLoad16(_p))
-#define ABSL_INTERNAL_UNALIGNED_LOAD32(_p) \
- (absl::base_internal::UnalignedLoad32(_p))
-#define ABSL_INTERNAL_UNALIGNED_LOAD64(_p) \
- (absl::base_internal::UnalignedLoad64(_p))
-
-#define ABSL_INTERNAL_UNALIGNED_STORE16(_p, _val) \
- (absl::base_internal::UnalignedStore16(_p, _val))
-#define ABSL_INTERNAL_UNALIGNED_STORE32(_p, _val) \
- (absl::base_internal::UnalignedStore32(_p, _val))
-#define ABSL_INTERNAL_UNALIGNED_STORE64(_p, _val) \
- (absl::base_internal::UnalignedStore64(_p, _val))
-
-#elif defined(__x86_64__) || defined(_M_X64) || defined(__i386) || \
- defined(_M_IX86) || defined(__ppc__) || defined(__PPC__) || \
- defined(__ppc64__) || defined(__PPC64__)
-
-// x86 and x86-64 can perform unaligned loads/stores directly;
-// modern PowerPC hardware can also do unaligned integer loads and stores;
-// but note: the FPU still sends unaligned loads and stores to a trap handler!
-
-#define ABSL_INTERNAL_UNALIGNED_LOAD16(_p) \
- (*reinterpret_cast<const uint16_t *>(_p))
-#define ABSL_INTERNAL_UNALIGNED_LOAD32(_p) \
- (*reinterpret_cast<const uint32_t *>(_p))
-#define ABSL_INTERNAL_UNALIGNED_LOAD64(_p) \
- (*reinterpret_cast<const uint64_t *>(_p))
-
-#define ABSL_INTERNAL_UNALIGNED_STORE16(_p, _val) \
- (*reinterpret_cast<uint16_t *>(_p) = (_val))
-#define ABSL_INTERNAL_UNALIGNED_STORE32(_p, _val) \
- (*reinterpret_cast<uint32_t *>(_p) = (_val))
-#define ABSL_INTERNAL_UNALIGNED_STORE64(_p, _val) \
- (*reinterpret_cast<uint64_t *>(_p) = (_val))
-
-#elif defined(__arm__) && \
- !defined(__ARM_ARCH_5__) && \
- !defined(__ARM_ARCH_5T__) && \
- !defined(__ARM_ARCH_5TE__) && \
- !defined(__ARM_ARCH_5TEJ__) && \
- !defined(__ARM_ARCH_6__) && \
- !defined(__ARM_ARCH_6J__) && \
- !defined(__ARM_ARCH_6K__) && \
- !defined(__ARM_ARCH_6Z__) && \
- !defined(__ARM_ARCH_6ZK__) && \
- !defined(__ARM_ARCH_6T2__)
-
-
-// ARMv7 and newer support native unaligned accesses, but only of 16-bit
-// and 32-bit values (not 64-bit); older versions either raise a fatal signal,
-// do an unaligned read and rotate the words around a bit, or do the reads very
-// slowly (trip through kernel mode). There's no simple #define that says just
-// "ARMv7 or higher", so we have to filter away all ARMv5 and ARMv6
-// sub-architectures. Newer gcc (>= 4.6) set an __ARM_FEATURE_ALIGNED #define,
-// so in time, maybe we can move on to that.
-//
-// This is a mess, but there's not much we can do about it.
-//
-// To further complicate matters, only LDR instructions (single reads) are
-// allowed to be unaligned, not LDRD (two reads) or LDM (many reads). Unless we
-// explicitly tell the compiler that these accesses can be unaligned, it can and
-// will combine accesses. On armcc, the way to signal this is done by accessing
-// through the type (uint32_t __packed *), but GCC has no such attribute
-// (it ignores __attribute__((packed)) on individual variables). However,
-// we can tell it that a _struct_ is unaligned, which has the same effect,
-// so we do that.
-
-namespace absl {
-namespace base_internal {
-
-struct Unaligned16Struct {
- uint16_t value;
- uint8_t dummy; // To make the size non-power-of-two.
-} ABSL_ATTRIBUTE_PACKED;
-
-struct Unaligned32Struct {
- uint32_t value;
- uint8_t dummy; // To make the size non-power-of-two.
-} ABSL_ATTRIBUTE_PACKED;
-
-} // namespace base_internal
-} // namespace absl
-
-#define ABSL_INTERNAL_UNALIGNED_LOAD16(_p) \
- ((reinterpret_cast<const ::absl::base_internal::Unaligned16Struct *>(_p)) \
- ->value)
-#define ABSL_INTERNAL_UNALIGNED_LOAD32(_p) \
- ((reinterpret_cast<const ::absl::base_internal::Unaligned32Struct *>(_p)) \
- ->value)
-
-#define ABSL_INTERNAL_UNALIGNED_STORE16(_p, _val) \
- ((reinterpret_cast< ::absl::base_internal::Unaligned16Struct *>(_p)) \
- ->value = (_val))
-#define ABSL_INTERNAL_UNALIGNED_STORE32(_p, _val) \
- ((reinterpret_cast< ::absl::base_internal::Unaligned32Struct *>(_p)) \
- ->value = (_val))
-
-namespace absl {
-namespace base_internal {
-
-inline uint64_t UnalignedLoad64(const void *p) {
- uint64_t t;
- memcpy(&t, p, sizeof t);
- return t;
-}
-
-inline void UnalignedStore64(void *p, uint64_t v) { memcpy(p, &v, sizeof v); }
-
-} // namespace base_internal
-} // namespace absl
-
-#define ABSL_INTERNAL_UNALIGNED_LOAD64(_p) \
- (absl::base_internal::UnalignedLoad64(_p))
-#define ABSL_INTERNAL_UNALIGNED_STORE64(_p, _val) \
- (absl::base_internal::UnalignedStore64(_p, _val))
-
#else
-// ABSL_INTERNAL_NEED_ALIGNED_LOADS is defined when the underlying platform
-// doesn't support unaligned access.
-#define ABSL_INTERNAL_NEED_ALIGNED_LOADS
-
-// These functions are provided for architectures that don't support
-// unaligned loads and stores.
-
namespace absl {
namespace base_internal {