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bpo-27987: pymalloc: align by 16bytes on 64bit platform (GH-12850) 

(cherry picked from commit f0be4bbb9b)

Co-authored-by: Inada Naoki <songofacandy@gmail.com>
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Miss Islington (bot) 2019-05-25 10:18:34 -07:00 committed by GitHub
parent 2156fec1f7
commit 1b85f4ec45
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3
Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst Normal file
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@ -0,0 +1,3 @@
pymalloc returns memory blocks aligned by 16 bytes, instead of 8 bytes, on
64-bit platforms to conform x86-64 ABI. Recent compilers assume this alignment
more often. Patch by Inada Naoki.

6
Objects/obmalloc.c
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@ -788,8 +788,14 @@ static int running_on_valgrind = -1;
*
* You shouldn't change this unless you know what you are doing.
*/
#if SIZEOF_VOID_P > 4
#define ALIGNMENT 16 /* must be 2^N */
#define ALIGNMENT_SHIFT 4
#else
#define ALIGNMENT 8 /* must be 2^N */
#define ALIGNMENT_SHIFT 3
#endif
/* Return the number of bytes in size class I, as a uint. */
#define INDEX2SIZE(I) (((uint)(I) + 1) << ALIGNMENT_SHIFT)