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bpo-39465: Add pycore_atomic_funcs.h internal header #20766

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Merged
vstinner merged 4 commits into from
Dec 23, 2020
Merged

bpo-39465: Add pycore_atomic_funcs.h internal header #20766

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23cfadf
bpo-39465: Add pycore_atomic_funcs.h header
vstinner Jun 9, 2020
08a37ee
Fix Windows impl
vstinner Dec 23, 2020
afebc16
Fix 32-bit Windows
vstinner Dec 23, 2020
2de9950
Enhance sizeof() assert
vstinner Dec 23, 2020
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Fix Windows impl
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@vstinner
vstinner committed Dec 23, 2020
commit 08a37eef500672bb0fcf29d578e097ae49f5d999
27 changes: 16 additions & 11 deletions Include/internal/pycore_atomic_funcs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,11 @@ extern "C" {
# error "this header requires Py_BUILD_CORE define"
#endif

#if defined(_MSC_VER)
# include <intrin.h> // _InterlockedExchange()
#endif


// Use builtin atomic operations in GCC >= 4.7 and clang
#ifdef HAVE_BUILTIN_ATOMIC

Expand All @@ -38,32 +43,32 @@ static inline Py_ssize_t _Py_atomic_size_get(Py_ssize_t *var)
{
#if SIZEOF_VOID_P == 8
Py_BUILD_ASSERT(sizeof(LONG64) == sizeof(Py_ssize_t));
volatile LONG64 *lvar = (volatile LONG64 *)var;
volatile LONG64 *volatile_var = (volatile LONG64 *)var;
LONG64 old;
do {
old = *lvar;
} while(_InterlockedCompareExchange64(lvar, old, old) != old);
old = *volatile_var;
} while(_InterlockedCompareExchange64(volatile_var, old, old) != old);
#else
Py_BUILD_ASSERT(sizeof(LONG) == sizeof(Py_ssize_t));
volatile LONG *lvar = (volatile LONG *)var;
volatile LONG *volatile_var = (volatile LONG *)var;
LONG old;
do {
old = *lvar;
} while(_InterlockedCompareExchange(lvar, old, old) != old);
old = *volatile_var;
} while(_InterlockedCompareExchange(volatile_var, old, old) != old);
#endif
return old;
}

static inline void _Py_atomic_size_set(Py_ssize_t *var, Py_ssize_t value)
{
#if SIZEOF_VOID_P == 8
Py_BUILD_ASSERT(sizeof(long) == sizeof(Py_ssize_t));
volatile long *lvar = (volatile long *)var;
_InterlockedExchange(lvar, value);
Py_BUILD_ASSERT(sizeof(LONG64) == sizeof(Py_ssize_t));
volatile LONG64 *volatile_var = (volatile LONG64 *)var;
_InterlockedExchange64(volatile_var, value);
#else
Py_BUILD_ASSERT(sizeof(LONG) == sizeof(Py_ssize_t));
volatile LONG *lvar = (volatile LONG *)var;
_InterlockedExchange(lvar, value);
volatile LONG *volatile_var = (volatile LONG *)var;
_InterlockedExchange(volatile_var, value);
#endif
}

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