malloc: Avoid optimizer warning with GCC 7 and -O3
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@ -1,3 +1,8 @@
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2017-08-10 Florian Weimer <fweimer@redhat.com>
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* malloc/malloc.c (get_max_fast): Reimplement as an inline
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function which calls __builtin_unreachable.
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2017-08-10 Mike FABIAN <mfabian@redhat.com>
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* stdlib/tst-strfmon_l.c: Fix test cases to agree with the changes in
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@ -1658,6 +1658,9 @@ typedef struct malloc_chunk *mfastbinptr;
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#define arena_is_corrupt(A) (((A)->flags & ARENA_CORRUPTION_BIT))
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#define set_arena_corrupt(A) ((A)->flags |= ARENA_CORRUPTION_BIT)
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/* Maximum size of memory handled in fastbins. */
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static INTERNAL_SIZE_T global_max_fast;
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/*
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Set value of max_fast.
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Use impossibly small value if 0.
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@ -1668,8 +1671,20 @@ typedef struct malloc_chunk *mfastbinptr;
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#define set_max_fast(s) \
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global_max_fast = (((s) == 0) \
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? SMALLBIN_WIDTH : ((s + SIZE_SZ) & ~MALLOC_ALIGN_MASK))
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#define get_max_fast() global_max_fast
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static inline INTERNAL_SIZE_T
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get_max_fast (void)
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{
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/* Tell the GCC optimizers that global_max_fast is never larger
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than MAX_FAST_SIZE. This avoids out-of-bounds array accesses in
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_int_malloc after constant propagation of the size parameter.
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(The code never executes because malloc preserves the
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global_max_fast invariant, but the optimizers may not recognize
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this.) */
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if (global_max_fast > MAX_FAST_SIZE)
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__builtin_unreachable ();
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return global_max_fast;
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}
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/*
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----------- Internal state representation and initialization -----------
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@ -1797,9 +1812,6 @@ static struct malloc_par mp_ =
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#endif
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};
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/* Maximum size of memory handled in fastbins. */
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static INTERNAL_SIZE_T global_max_fast;
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/*
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Initialize a malloc_state struct.
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