[Python-checkins] bpo-39465: Add pycore_atomic_funcs.h header (GH-20766)
vstinner
webhook-mailer at python.org
Tue Dec 22 21:41:12 EST 2020
https://github.com/python/cpython/commit/52a327c1cbb86c7f2f5c460645889b23615261bf
commit: 52a327c1cbb86c7f2f5c460645889b23615261bf
branch: master
author: Victor Stinner <vstinner at python.org>
committer: vstinner <vstinner at python.org>
date: 2020-12-23T03:41:08+01:00
summary:
bpo-39465: Add pycore_atomic_funcs.h header (GH-20766)
Add pycore_atomic_funcs.h internal header file: similar to
pycore_atomic.h but don't require to declare variables as atomic.
Add _Py_atomic_size_get() and _Py_atomic_size_set() functions.
files:
A Include/internal/pycore_atomic_funcs.h
M Include/internal/pycore_atomic.h
M Makefile.pre.in
M Modules/_testinternalcapi.c
M PCbuild/pythoncore.vcxproj
M PCbuild/pythoncore.vcxproj.filters
M configure
M configure.ac
M pyconfig.h.in
diff --git a/Include/internal/pycore_atomic.h b/Include/internal/pycore_atomic.h
index 1d5c5621677eb..3d42e54464c4c 100644
--- a/Include/internal/pycore_atomic.h
+++ b/Include/internal/pycore_atomic.h
@@ -11,8 +11,8 @@ extern "C" {
#include "dynamic_annotations.h" /* _Py_ANNOTATE_MEMORY_ORDER */
#include "pyconfig.h"
-#if defined(HAVE_STD_ATOMIC)
-#include <stdatomic.h>
+#ifdef HAVE_STD_ATOMIC
+# include <stdatomic.h>
#endif
@@ -62,7 +62,7 @@ typedef struct _Py_atomic_int {
#define _Py_atomic_load_explicit(ATOMIC_VAL, ORDER) \
atomic_load_explicit(&((ATOMIC_VAL)->_value), ORDER)
-/* Use builtin atomic operations in GCC >= 4.7 */
+// Use builtin atomic operations in GCC >= 4.7 and clang
#elif defined(HAVE_BUILTIN_ATOMIC)
typedef enum _Py_memory_order {
diff --git a/Include/internal/pycore_atomic_funcs.h b/Include/internal/pycore_atomic_funcs.h
new file mode 100644
index 0000000000000..a708789cea733
--- /dev/null
+++ b/Include/internal/pycore_atomic_funcs.h
@@ -0,0 +1,94 @@
+/* Atomic functions: similar to pycore_atomic.h, but don't need
+ to declare variables as atomic.
+
+ Py_ssize_t type:
+
+ * value = _Py_atomic_size_get(&var)
+ * _Py_atomic_size_set(&var, value)
+
+ Use sequentially-consistent ordering (__ATOMIC_SEQ_CST memory order):
+ enforce total ordering with all other atomic functions.
+*/
+#ifndef Py_ATOMIC_FUNC_H
+#define Py_ATOMIC_FUNC_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef Py_BUILD_CORE
+# 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
+
+static inline Py_ssize_t _Py_atomic_size_get(Py_ssize_t *var)
+{
+ return __atomic_load_n(var, __ATOMIC_SEQ_CST);
+}
+
+static inline void _Py_atomic_size_set(Py_ssize_t *var, Py_ssize_t value)
+{
+ __atomic_store_n(var, value, __ATOMIC_SEQ_CST);
+}
+
+#elif defined(_MSC_VER)
+
+static inline Py_ssize_t _Py_atomic_size_get(Py_ssize_t *var)
+{
+#if SIZEOF_VOID_P == 8
+ Py_BUILD_ASSERT(sizeof(__int64) == sizeof(*var));
+ volatile __int64 *volatile_var = (volatile __int64 *)var;
+ __int64 old;
+ do {
+ old = *volatile_var;
+ } while(_InterlockedCompareExchange64(volatile_var, old, old) != old);
+#else
+ Py_BUILD_ASSERT(sizeof(long) == sizeof(*var));
+ volatile long *volatile_var = (volatile long *)var;
+ long old;
+ do {
+ 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(__int64) == sizeof(*var));
+ volatile __int64 *volatile_var = (volatile __int64 *)var;
+ _InterlockedExchange64(volatile_var, value);
+#else
+ Py_BUILD_ASSERT(sizeof(long) == sizeof(*var));
+ volatile long *volatile_var = (volatile long *)var;
+ _InterlockedExchange(volatile_var, value);
+#endif
+}
+
+#else
+// Fallback implementation using volatile
+
+static inline Py_ssize_t _Py_atomic_size_get(Py_ssize_t *var)
+{
+ volatile Py_ssize_t *volatile_var = (volatile Py_ssize_t *)var;
+ return *volatile_var;
+}
+
+static inline void _Py_atomic_size_set(Py_ssize_t *var, Py_ssize_t value)
+{
+ volatile Py_ssize_t *volatile_var = (volatile Py_ssize_t *)var;
+ *volatile_var = value;
+}
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* Py_ATOMIC_FUNC_H */
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 69ed251936a60..5c93b0b3fa9c6 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1111,6 +1111,7 @@ PYTHON_HEADERS= \
$(srcdir)/Include/internal/pycore_abstract.h \
$(srcdir)/Include/internal/pycore_accu.h \
$(srcdir)/Include/internal/pycore_atomic.h \
+ $(srcdir)/Include/internal/pycore_atomic_funcs.h \
$(srcdir)/Include/internal/pycore_bitutils.h \
$(srcdir)/Include/internal/pycore_bytes_methods.h \
$(srcdir)/Include/internal/pycore_call.h \
diff --git a/Modules/_testinternalcapi.c b/Modules/_testinternalcapi.c
index df4725ea0a1c8..ab6c5965d1661 100644
--- a/Modules/_testinternalcapi.c
+++ b/Modules/_testinternalcapi.c
@@ -12,6 +12,7 @@
#define PY_SSIZE_T_CLEAN
#include "Python.h"
+#include "pycore_atomic_funcs.h" // _Py_atomic_int_get()
#include "pycore_bitutils.h" // _Py_bswap32()
#include "pycore_gc.h" // PyGC_Head
#include "pycore_hashtable.h" // _Py_hashtable_new()
@@ -267,6 +268,17 @@ test_set_config(PyObject *Py_UNUSED(self), PyObject *dict)
}
+static PyObject*
+test_atomic_funcs(PyObject *self, PyObject *Py_UNUSED(args))
+{
+ // Test _Py_atomic_size_get() and _Py_atomic_size_set()
+ Py_ssize_t var = 1;
+ _Py_atomic_size_set(&var, 2);
+ assert(_Py_atomic_size_get(&var) == 2);
+ Py_RETURN_NONE;
+}
+
+
static PyMethodDef TestMethods[] = {
{"get_configs", get_configs, METH_NOARGS},
{"get_recursion_depth", get_recursion_depth, METH_NOARGS},
@@ -276,6 +288,7 @@ static PyMethodDef TestMethods[] = {
{"test_hashtable", test_hashtable, METH_NOARGS},
{"get_config", test_get_config, METH_NOARGS},
{"set_config", test_set_config, METH_O},
+ {"test_atomic_funcs", test_atomic_funcs, METH_NOARGS},
{NULL, NULL} /* sentinel */
};
diff --git a/PCbuild/pythoncore.vcxproj b/PCbuild/pythoncore.vcxproj
index bbceb025c0c22..fd27dea9daec7 100644
--- a/PCbuild/pythoncore.vcxproj
+++ b/PCbuild/pythoncore.vcxproj
@@ -168,6 +168,7 @@
<ClInclude Include="..\Include\internal\pycore_abstract.h" />
<ClInclude Include="..\Include\internal\pycore_accu.h" />
<ClInclude Include="..\Include\internal\pycore_atomic.h" />
+ <ClInclude Include="..\Include\internal\pycore_atomic_funcs.h" />
<ClInclude Include="..\Include\internal\pycore_bitutils.h" />
<ClInclude Include="..\Include\internal\pycore_bytes_methods.h" />
<ClInclude Include="..\Include\internal\pycore_call.h" />
diff --git a/PCbuild/pythoncore.vcxproj.filters b/PCbuild/pythoncore.vcxproj.filters
index ee1aa90bf7688..75a653dcbdab2 100644
--- a/PCbuild/pythoncore.vcxproj.filters
+++ b/PCbuild/pythoncore.vcxproj.filters
@@ -486,6 +486,9 @@
<ClInclude Include="..\Include\internal\pycore_atomic.h">
<Filter>Include\internal</Filter>
</ClInclude>
+ <ClInclude Include="..\Include\internal\pycore_atomic_funcs.h">
+ <Filter>Include</Filter>
+ </ClInclude>
<ClInclude Include="..\Include\internal\pycore_bitutils.h">
<Filter>Include\internal</Filter>
</ClInclude>
diff --git a/configure b/configure
index f07edfff266a0..530c04a0edee3 100755
--- a/configure
+++ b/configure
@@ -15429,6 +15429,7 @@ _ACEOF
fi
+
EXT_SUFFIX=.${SOABI}${SHLIB_SUFFIX}
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking LDVERSION" >&5
@@ -17095,16 +17096,17 @@ $as_echo "#define HAVE_STD_ATOMIC 1" >>confdefs.h
fi
-# Check for GCC >= 4.7 __atomic builtins
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GCC >= 4.7 __atomic builtins" >&5
-$as_echo_n "checking for GCC >= 4.7 __atomic builtins... " >&6; }
+# Check for GCC >= 4.7 and clang __atomic builtin functions
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for builtin __atomic_load_n and __atomic_store_n functions" >&5
+$as_echo_n "checking for builtin __atomic_load_n and __atomic_store_n functions... " >&6; }
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
- volatile int val = 1;
+ int val;
int main() {
- __atomic_load_n(&val, __ATOMIC_SEQ_CST);
+ __atomic_store_n(&val, 1, __ATOMIC_SEQ_CST);
+ (void)__atomic_load_n(&val, __ATOMIC_SEQ_CST);
return 0;
}
diff --git a/configure.ac b/configure.ac
index ee5573cf64431..39eadfedfba02 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5586,14 +5586,15 @@ if test "$have_stdatomic_h" = yes; then
[Has stdatomic.h with atomic_int and atomic_uintptr_t])
fi
-# Check for GCC >= 4.7 __atomic builtins
-AC_MSG_CHECKING(for GCC >= 4.7 __atomic builtins)
+# Check for GCC >= 4.7 and clang __atomic builtin functions
+AC_MSG_CHECKING(for builtin __atomic_load_n and __atomic_store_n functions)
AC_LINK_IFELSE(
[
AC_LANG_SOURCE([[
- volatile int val = 1;
+ int val;
int main() {
- __atomic_load_n(&val, __ATOMIC_SEQ_CST);
+ __atomic_store_n(&val, 1, __ATOMIC_SEQ_CST);
+ (void)__atomic_load_n(&val, __ATOMIC_SEQ_CST);
return 0;
}
]])
@@ -5602,7 +5603,7 @@ AC_LINK_IFELSE(
AC_MSG_RESULT($have_builtin_atomic)
if test "$have_builtin_atomic" = yes; then
- AC_DEFINE(HAVE_BUILTIN_ATOMIC, 1, [Has builtin atomics])
+ AC_DEFINE(HAVE_BUILTIN_ATOMIC, 1, [Has builtin __atomic_load_n() and __atomic_store_n() functions])
fi
# ensurepip option
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 6ff5fc968a30c..045cbd53aee59 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -115,7 +115,7 @@
/* Define if `unsetenv` does not return an int. */
#undef HAVE_BROKEN_UNSETENV
-/* Has builtin atomics */
+/* Has builtin __atomic_load_n() and __atomic_store_n() functions */
#undef HAVE_BUILTIN_ATOMIC
/* Define to 1 if you have the 'chflags' function. */
@@ -287,6 +287,9 @@
/* Define to 1 if you have the `dup3' function. */
#undef HAVE_DUP3
+/* Define if you have the '_dyld_shared_cache_contains_path' function. */
+#undef HAVE_DYLD_SHARED_CACHE_CONTAINS_PATH
+
/* Defined when any dynamic module loading is enabled. */
#undef HAVE_DYNAMIC_LOADING
@@ -787,9 +790,6 @@
/* Define if you have the 'prlimit' functions. */
#undef HAVE_PRLIMIT
-/* Define if you have the '_dyld_shared_cache_contains_path' function. */
-#undef HAVE_DYLD_SHARED_CACHE_CONTAINS_PATH
-
/* Define to 1 if you have the <process.h> header file. */
#undef HAVE_PROCESS_H
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