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Take <atomic> for granted in port/atomic_pointer.h.

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C++11 requires <atomic>. This lets us remove the header detection
(LEVELDB_ATOMIC_PRESENT) and simplify port/atomic_pointer.h.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189919098
This commit is contained in:
costan 2018-03-21 09:26:49 -07:00 committed by Victor Costan
parent 74f032ff6f
commit 04f39105c5
3 changed files with 5 additions and 85 deletions
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3
CMakeLists.txt
View File

@ -25,9 +25,6 @@ test_big_endian(LEVELDB_IS_BIG_ENDIAN)
include(CheckIncludeFile)
check_include_file("unistd.h" HAVE_UNISTD_H)
include(CheckIncludeFileCXX)
check_include_file_cxx("atomic" LEVELDB_ATOMIC_PRESENT)
include(CheckLibraryExists)
check_library_exists(crc32c crc32c_value "" HAVE_CRC32C)
check_library_exists(snappy snappy_compress "" HAVE_SNAPPY)

80
port/atomic_pointer.h
View File

@ -19,11 +19,9 @@
#define PORT_ATOMIC_POINTER_H_
#include <stdint.h>
#ifdef LEVELDB_ATOMIC_PRESENT
#include <atomic>
#elif defined(__APPLE__)
#include <libkern/OSAtomic.h>
#endif
#ifdef OS_WIN
#include <windows.h>
#endif
@ -55,11 +53,7 @@ namespace port {
// Mac OS
#elif defined(__APPLE__)
inline void MemoryBarrier() {
#if defined(LEVELDB_ATOMIC_PRESENT)
std::atomic_thread_fence(std::memory_order_seq_cst);
#else
OSMemoryBarrier();
#endif // defined(LEVELDB_ATOMIC_PRESENT)
}
#define LEVELDB_HAVE_MEMORY_BARRIER
@ -124,7 +118,7 @@ inline void MemoryBarrier() {
#endif
// AtomicPointer built using platform-specific MemoryBarrier()
// AtomicPointer built using platform-specific MemoryBarrier().
#if defined(LEVELDB_HAVE_MEMORY_BARRIER)
class AtomicPointer {
private:
@ -145,8 +139,8 @@ class AtomicPointer {
}
};
// AtomicPointer based on <cstdatomic>
#elif defined(LEVELDB_ATOMIC_PRESENT)
// AtomicPointer based on C++11 <atomic>.
#else
class AtomicPointer {
private:
std::atomic<void*> rep_;
@ -167,70 +161,6 @@ class AtomicPointer {
}
};
// Atomic pointer based on sparc memory barriers
#elif defined(__sparcv9) && defined(__GNUC__)
class AtomicPointer {
private:
void* rep_;
public:
AtomicPointer() { }
explicit AtomicPointer(void* v) : rep_(v) { }
inline void* Acquire_Load() const {
void* val;
__asm__ __volatile__ (
"ldx [%[rep_]], %[val] \n\t"
"membar #LoadLoad|#LoadStore \n\t"
: [val] "=r" (val)
: [rep_] "r" (&rep_)
: "memory");
return val;
}
inline void Release_Store(void* v) {
__asm__ __volatile__ (
"membar #LoadStore|#StoreStore \n\t"
"stx %[v], [%[rep_]] \n\t"
:
: [rep_] "r" (&rep_), [v] "r" (v)
: "memory");
}
inline void* NoBarrier_Load() const { return rep_; }
inline void NoBarrier_Store(void* v) { rep_ = v; }
};
// Atomic pointer based on ia64 acq/rel
#elif defined(__ia64) && defined(__GNUC__)
class AtomicPointer {
private:
void* rep_;
public:
AtomicPointer() { }
explicit AtomicPointer(void* v) : rep_(v) { }
inline void* Acquire_Load() const {
void* val ;
__asm__ __volatile__ (
"ld8.acq %[val] = [%[rep_]] \n\t"
: [val] "=r" (val)
: [rep_] "r" (&rep_)
: "memory"
);
return val;
}
inline void Release_Store(void* v) {
__asm__ __volatile__ (
"st8.rel [%[rep_]] = %[v] \n\t"
:
: [rep_] "r" (&rep_), [v] "r" (v)
: "memory"
);
}
inline void* NoBarrier_Load() const { return rep_; }
inline void NoBarrier_Store(void* v) { rep_ = v; }
};
// We have neither MemoryBarrier(), nor <atomic>
#else
#error Please implement AtomicPointer for this platform.
#endif
#undef LEVELDB_HAVE_MEMORY_BARRIER

7
port/port_config.h.in
View File

@ -26,11 +26,4 @@
#cmakedefine01 LEVELDB_IS_BIG_ENDIAN
#endif // !defined(LEVELDB_IS_BIG_ENDIAN)
// Define to 1 if you have the <atomic> header.
// NOTE: <atomic> was standardized in C++11, which will be required to build
// LevelDB soon.
#if !defined(LEVELDB_ATOMIC_PRESENT)
#cmakedefine01 LEVELDB_ATOMIC_PRESENT
#endif // !defined(LEVELDB_ATOMIC_PRESENT)
#endif // STORAGE_LEVELDB_PORT_PORT_CONFIG_H_