tbegin.

Transaction Begin

tbegin. R

Initiates a hardware transaction. If the transaction fails, execution rolls back to this point. Sets CR0 based on success/failure.

Details

The tbegin instruction initiates a transactional memory operation. In synthetic TM mode, every transaction following this instruction fails immediately, and the failure handler is invoked. This behavior ensures minimal disruption during the removal of transactional memory from the architecture.

Pseudocode Operation

StartTransaction(); CR0 <- Status

Programming Note

In synthetic TM mode, transactions initiated by tbegin will fail immediately, invoking the failure handler. Ensure that your application logic correctly handles transaction failures to maintain data integrity.

Example

tbegin. 0

Encoding

Binary Layout
31
0
/
6
R
11
/
16
654
21
1
31
 
Format X-form
Opcode 0x7C00051D
Extension Transactional Memory
Registers Altered CR0

Operands

  • R
    Rollback Handler (0=External, 1=Internal)