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arch-arm.h
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1 /*-------------------------------------------------------------------------
2  *
3  * arch-arm.h
4  * Atomic operations considerations specific to ARM
5  *
6  * Portions Copyright (c) 2013-2024, PostgreSQL Global Development Group
7  *
8  * NOTES:
9  *
10  * src/include/port/atomics/arch-arm.h
11  *
12  *-------------------------------------------------------------------------
13  */
14 
15 /* intentionally no include guards, should only be included by atomics.h */
16 #ifndef INSIDE_ATOMICS_H
17 #error "should be included via atomics.h"
18 #endif
19 
20 /*
21  * 64 bit atomics on ARM32 are implemented using kernel fallbacks and thus
22  * might be slow, so disable entirely. On ARM64 that problem doesn't exist.
23  */
24 #if !defined(__aarch64__)
25 #define PG_DISABLE_64_BIT_ATOMICS
26 #else
27 /*
28  * Architecture Reference Manual for ARMv8 states aligned read/write to/from
29  * general purpose register is atomic.
30  */
31 #define PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY
32 #endif /* __aarch64__ */