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author | Florian Weimer <fweimer@redhat.com> | 2017-08-10 15:58:28 +0200 |
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committer | Florian Weimer <fweimer@redhat.com> | 2017-08-10 15:58:28 +0200 |
commit | eac43cbb8d808a40004aa0a4a286f5c5155beccb (patch) | |
tree | b17052f4a48a6fd8da44c12f1fd61b4bce196dcf /malloc | |
parent | bd80111ed9cb93b2d56720dcd1d1f259616c27ae (diff) | |
download | glibc-eac43cbb8d808a40004aa0a4a286f5c5155beccb.zip glibc-eac43cbb8d808a40004aa0a4a286f5c5155beccb.tar.gz glibc-eac43cbb8d808a40004aa0a4a286f5c5155beccb.tar.bz2 |
malloc: Avoid optimizer warning with GCC 7 and -O3
Diffstat (limited to 'malloc')
-rw-r--r-- | malloc/malloc.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c index 54e406b..e3ff778 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -1658,6 +1658,9 @@ typedef struct malloc_chunk *mfastbinptr; #define arena_is_corrupt(A) (((A)->flags & ARENA_CORRUPTION_BIT)) #define set_arena_corrupt(A) ((A)->flags |= ARENA_CORRUPTION_BIT) +/* Maximum size of memory handled in fastbins. */ +static INTERNAL_SIZE_T global_max_fast; + /* Set value of max_fast. Use impossibly small value if 0. @@ -1668,8 +1671,20 @@ typedef struct malloc_chunk *mfastbinptr; #define set_max_fast(s) \ global_max_fast = (((s) == 0) \ ? SMALLBIN_WIDTH : ((s + SIZE_SZ) & ~MALLOC_ALIGN_MASK)) -#define get_max_fast() global_max_fast +static inline INTERNAL_SIZE_T +get_max_fast (void) +{ + /* Tell the GCC optimizers that global_max_fast is never larger + than MAX_FAST_SIZE. This avoids out-of-bounds array accesses in + _int_malloc after constant propagation of the size parameter. + (The code never executes because malloc preserves the + global_max_fast invariant, but the optimizers may not recognize + this.) */ + if (global_max_fast > MAX_FAST_SIZE) + __builtin_unreachable (); + return global_max_fast; +} /* ----------- Internal state representation and initialization ----------- @@ -1797,9 +1812,6 @@ static struct malloc_par mp_ = #endif }; -/* Maximum size of memory handled in fastbins. */ -static INTERNAL_SIZE_T global_max_fast; - /* Initialize a malloc_state struct. |