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Merge pull request #1316 from facebook/coldDict

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Cold dictionary mitigation
This commit is contained in:
Yann Collet
2018-09-14 10:37:46 -07:00
committed by GitHub
parent b287b8f7c6 5512400677
commit 0e5b447aaa
6 changed files with 189 additions and 106 deletions
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lib/common/compiler.h
+22 -5
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@@ -89,20 +89,37 @@
#endif
/* prefetch
* can be disabled, by declaring NO_PREFETCH macro */
* can be disabled, by declaring NO_PREFETCH macro
* All prefetch invocations use a single default locality 2,
* generating instruction prefetcht1,
* which, according to Intel, means "load data into L2 cache".
* This is a good enough "middle ground" for the time being,
* though in theory, it would be better to specialize locality depending on data being prefetched.
* Tests could not determine any sensible difference based on locality value. */
#if defined(NO_PREFETCH)
# define PREFETCH(ptr) /* disabled */
# define PREFETCH(ptr) (void)(ptr) /* disabled */
#else
# if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_I86)) /* _mm_prefetch() is not defined outside of x86/x64 */
# include <mmintrin.h> /* https://msdn.microsoft.com/fr-fr/library/84szxsww(v=vs.90).aspx */
# define PREFETCH(ptr) _mm_prefetch((const char*)ptr, _MM_HINT_T0)
# define PREFETCH(ptr) _mm_prefetch((const char*)(ptr), _MM_HINT_T1)
# elif defined(__GNUC__) && ( (__GNUC__ >= 4) || ( (__GNUC__ == 3) && (__GNUC_MINOR__ >= 1) ) )
# define PREFETCH(ptr) __builtin_prefetch(ptr, 0, 0)
# define PREFETCH(ptr) __builtin_prefetch((ptr), 0 /* rw==read */, 2 /* locality */)
# else
# define PREFETCH(ptr) /* disabled */
# define PREFETCH(ptr) (void)(ptr) /* disabled */
# endif
#endif /* NO_PREFETCH */
#define CACHELINE_SIZE 64
#define PREFETCH_AREA(p, s) { \
const char* const _ptr = (const char*)(p); \
size_t const _size = (size_t)(s); \
size_t _pos; \
for (_pos=0; _pos<_size; _pos+=CACHELINE_SIZE) { \
PREFETCH(_ptr + _pos); \
} \
}
/* disable warnings */
#ifdef _MSC_VER /* Visual Studio */
# include <intrin.h> /* For Visual 2005 */