Add atomic fetch-and-op and compare-exchange functions #4552
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This commit adds a new set of compare-and-exchange functions. These functions have a signature similar to the functions found in C11. The old cmpset functions are now deprecated and defined in terms of the new compare-and-exchange functions. All asm backends have been updated. Signed-off-by: Nathan Hjelm <[email protected]>
Signed-off-by: Nathan Hjelm <[email protected]>
This commit eliminates the old opal_atomic_bool_cmpset functions. They have been replaced by the opal_atomic_compare_exchange_strong functions. Signed-off-by: Nathan Hjelm <[email protected]>
This commit renames the arithmetic atomic operations in opal to indicate that they return the new value not the old value. This naming differentiates these routines from new functions that return the old value. Signed-off-by: Nathan Hjelm <[email protected]>
This commit adds support for fetch-and-op atomics. This is needed because and and or are irreversible operations so there needs to be a way to get the old value atomically. These are also the only semantics supported by C11 (there is not atomic_op_fetch, just atomic_fetch_op). The old op-and-fetch atomics have been defined in terms of fetch-and-op. Signed-off-by: Nathan Hjelm <[email protected]>
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bosilca
approved these changes
Dec 1, 2017
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This PR contains the following updates to atomics in opal:
Remove opal_atomic_cmpset_* operations.
Add new compare-exchange functions with signature that matches C11. These functions still return a boolean but take a pointer to the compare value. The old value is stored over the compare value.
Add atomic fetch-and-op functions. These replace the old op-and-fetch functions in the underlying atomic implementations. The old atomic arithmetic operations have been renamed from opal_atomic_op_* to opal_atomic_op_fetch_*.