__sync_bool_compare_and_swap汇编实现https://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html#Atomic-Builtins带有C/C++表达式的内联汇编格式为:__asm__ __volatile__("Instruction List" : Output : Input : Clobber/Modify);其中每项的概念及功能⽤法描述如下:1、 __asm___...
You can use the Machine Interface's (MI) Compare and Swap (CMPSWP) instruction to access data in a multithreaded program.
A new compare and swap instruction provides for effectively simultaneously swapping 2 values which is useful for safely adding and deleting items from linked lists. Prior to the instruction the status of the two value are read at the locations to be swapped. During the instruction these locations...
If thecntloperand is not specified, the instruction proceeds as if the default value had been specified. The machine does not enforce that only the values enumerated above are used for thecntloperand. When specified, use of any value other than those enumerated above may result in unpredictable...
Prior to the instruction the status of the two value are read at the locations to be swapped. During the instruction these locations are checked again to ensure that no change has occurred at these locations before the instruction performs the swap of the two new values. The instruction then ...
In Linux, the `cmpxchg` instruction is used to implement CAS operations. This instruction takes three operands: a memory location (specified by a memory address), an expected value, and a new value. The `cmpxchg` instruction compares the current value in the specified memory location with the...
This instruction can be used with a LOCK prefix to allow the instruction to be executed atomi-cally. To simplify the interface to the processor’s bus, the destination operand receives a write cycle without regard to the result of the comparison. The destination operand is written back if the...
// Adding a lock prefix to an instruction on MP machine // VC++ doesn't like the lock prefix to be on a single line // so we can't insert a label after the lock prefix. // By emitting a lock prefix, we can define a label after it. ...
// Adding a lock prefix to an instruction on MP machine// VC++ doesn't like the lock prefix to be on a single line// so we can't insert a label after the lock prefix.// By emitting a lock prefix, we can define a label after it.#define LOCK_IF_MP(mp) __asm cmp mp, 0 \...
In some realizations, memory locations addressed by a sequentially performed nCAS or DCAS instruction are reserved (e.g., locked) in a predefined order in accordance with a fixed total order of memory locations. In this way, deadlock between concurrently executed instances of sequentially ...