[Python-checkins] cpython (merge 3.6 -> default): merge 3.6
benjamin.peterson
python-checkins at python.org
Sun Sep 18 22:19:43 EDT 2016
https://hg.python.org/cpython/rev/05e651a36113
changeset: 103939:05e651a36113
parent: 103937:715cf7db676d
parent: 103938:b3c60363252f
user: Benjamin Peterson <benjamin at python.org>
date: Sun Sep 18 19:19:38 2016 -0700
summary:
merge 3.6
files:
Objects/obmalloc.c | 100 +++++++-------------------------
1 files changed, 23 insertions(+), 77 deletions(-)
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
--- a/Objects/obmalloc.c
+++ b/Objects/obmalloc.c
@@ -1,5 +1,7 @@
#include "Python.h"
+#include <stdbool.h>
+
/* Defined in tracemalloc.c */
extern void _PyMem_DumpTraceback(int fd, const void *ptr);
@@ -37,16 +39,14 @@
#if defined(__has_feature) /* Clang */
#if __has_feature(address_sanitizer) /* is ASAN enabled? */
#define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS \
- __attribute__((no_address_safety_analysis)) \
- __attribute__ ((noinline))
+ __attribute__((no_address_safety_analysis))
#else
#define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
#endif
#else
#if defined(__SANITIZE_ADDRESS__) /* GCC 4.8.x, is ASAN enabled? */
#define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS \
- __attribute__((no_address_safety_analysis)) \
- __attribute__ ((noinline))
+ __attribute__((no_address_safety_analysis))
#else
#define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
#endif
@@ -1124,13 +1124,13 @@
}
/*
-Py_ADDRESS_IN_RANGE(P, POOL)
+address_in_range(P, POOL)
Return true if and only if P is an address that was allocated by pymalloc.
POOL must be the pool address associated with P, i.e., POOL = POOL_ADDR(P)
(the caller is asked to compute this because the macro expands POOL more than
once, and for efficiency it's best for the caller to assign POOL_ADDR(P) to a
-variable and pass the latter to the macro; because Py_ADDRESS_IN_RANGE is
+variable and pass the latter to the macro; because address_in_range is
called on every alloc/realloc/free, micro-efficiency is important here).
Tricky: Let B be the arena base address associated with the pool, B =
@@ -1155,7 +1155,7 @@
stores, etc), POOL is the correct address of P's pool, AO.address is the
correct base address of the pool's arena, and P must be within ARENA_SIZE of
AO.address. In addition, AO.address is not 0 (no arena can start at address 0
-(NULL)). Therefore Py_ADDRESS_IN_RANGE correctly reports that obmalloc
+(NULL)). Therefore address_in_range correctly reports that obmalloc
controls P.
Now suppose obmalloc does not control P (e.g., P was obtained via a direct
@@ -1196,51 +1196,21 @@
obmalloc in a small constant time, independent of the number of arenas
obmalloc controls. Since this test is needed at every entry point, it's
extremely desirable that it be this fast.
+*/
-Since Py_ADDRESS_IN_RANGE may be reading from memory which was not allocated
-by Python, it is important that (POOL)->arenaindex is read only once, as
-another thread may be concurrently modifying the value without holding the
-GIL. To accomplish this, the arenaindex_temp variable is used to store
-(POOL)->arenaindex for the duration of the Py_ADDRESS_IN_RANGE macro's
-execution. The caller of the macro is responsible for declaring this
-variable.
-*/
-#define Py_ADDRESS_IN_RANGE(P, POOL) \
- ((arenaindex_temp = (POOL)->arenaindex) < maxarenas && \
- (uptr)(P) - arenas[arenaindex_temp].address < (uptr)ARENA_SIZE && \
- arenas[arenaindex_temp].address != 0)
-
-
-/* This is only useful when running memory debuggers such as
- * Purify or Valgrind. Uncomment to use.
- *
-#define Py_USING_MEMORY_DEBUGGER
- */
-
-#ifdef Py_USING_MEMORY_DEBUGGER
-
-/* Py_ADDRESS_IN_RANGE may access uninitialized memory by design
- * This leads to thousands of spurious warnings when using
- * Purify or Valgrind. By making a function, we can easily
- * suppress the uninitialized memory reads in this one function.
- * So we won't ignore real errors elsewhere.
- *
- * Disable the macro and use a function.
- */
-
-#undef Py_ADDRESS_IN_RANGE
-
-#if defined(__GNUC__) && ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 1) || \
- (__GNUC__ >= 4))
-#define Py_NO_INLINE __attribute__((__noinline__))
-#else
-#define Py_NO_INLINE
-#endif
-
-/* Don't make static, to try to ensure this isn't inlined. */
-int Py_ADDRESS_IN_RANGE(void *P, poolp pool) Py_NO_INLINE;
-#undef Py_NO_INLINE
-#endif
+static bool ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
+address_in_range(void *p, poolp pool)
+{
+ // Since address_in_range may be reading from memory which was not allocated
+ // by Python, it is important that pool->arenaindex is read only once, as
+ // another thread may be concurrently modifying the value without holding
+ // the GIL. The following dance forces the compiler to read pool->arenaindex
+ // only once.
+ uint arenaindex = *((volatile uint *)&pool->arenaindex);
+ return arenaindex < maxarenas &&
+ (uptr)p - arenas[arenaindex].address < ARENA_SIZE &&
+ arenas[arenaindex].address != 0;
+}
/*==========================================================================*/
@@ -1485,7 +1455,6 @@
/* free */
-ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
static void
_PyObject_Free(void *ctx, void *p)
{
@@ -1493,9 +1462,6 @@
block *lastfree;
poolp next, prev;
uint size;
-#ifndef Py_USING_MEMORY_DEBUGGER
- uint arenaindex_temp;
-#endif
if (p == NULL) /* free(NULL) has no effect */
return;
@@ -1508,7 +1474,7 @@
#endif
pool = POOL_ADDR(p);
- if (Py_ADDRESS_IN_RANGE(p, pool)) {
+ if (address_in_range(p, pool)) {
/* We allocated this address. */
LOCK();
/* Link p to the start of the pool's freeblock list. Since
@@ -1714,16 +1680,12 @@
* return a non-NULL result.
*/
-ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
static void *
_PyObject_Realloc(void *ctx, void *p, size_t nbytes)
{
void *bp;
poolp pool;
size_t size;
-#ifndef Py_USING_MEMORY_DEBUGGER
- uint arenaindex_temp;
-#endif
if (p == NULL)
return _PyObject_Alloc(0, ctx, 1, nbytes);
@@ -1735,7 +1697,7 @@
#endif
pool = POOL_ADDR(p);
- if (Py_ADDRESS_IN_RANGE(p, pool)) {
+ if (address_in_range(p, pool)) {
/* We're in charge of this block */
size = INDEX2SIZE(pool->szidx);
if (nbytes <= size) {
@@ -2432,19 +2394,3 @@
}
#endif /* #ifdef WITH_PYMALLOC */
-
-
-#ifdef Py_USING_MEMORY_DEBUGGER
-/* Make this function last so gcc won't inline it since the definition is
- * after the reference.
- */
-int
-Py_ADDRESS_IN_RANGE(void *P, poolp pool)
-{
- uint arenaindex_temp = pool->arenaindex;
-
- return arenaindex_temp < maxarenas &&
- (uptr)P - arenas[arenaindex_temp].address < (uptr)ARENA_SIZE &&
- arenas[arenaindex_temp].address != 0;
-}
-#endif
--
Repository URL: https://hg.python.org/cpython
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