Nontransactional store instruction

Abstract

A NONTRANSACTIONAL STORE instruction, executed in transactional execution mode, performs stores that are retained, even if a transaction associated with the instruction aborts. The stores include user-specified information that may facilitate debugging of an aborted transaction.

1 . A computer program product for executing an instruction within a computing environment, said computer program product comprising:
 a computer readable storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising:
 obtaining, by a processor, a machine instruction for execution, the machine instruction being defined for computer execution according to a computer architecture, the machine instruction comprising:
 an operation code to specify a nontransactional store operation; 
 a first operand; and 
 a second operand to designate a location for the first operand; and 
 
 executing, by the processor, the machine instruction, the executing comprising:
 nontransactionally placing the first operand at the location specified by the second operand, wherein information stored at the second operand is retained despite an abort of a transaction associated with the machine instruction, and wherein the nontransactionally placing is delayed until an end of transactional execution mode of the processor. 
 
   
     
     
         2 . The computer program product of  claim 1 , wherein the end of transactional execution mode results from an end of an outermost transaction associated with the machine instruction or an abort condition. 
     
     
         3 . The computer program product of  claim 1 , wherein multiple nontransactional stores appear as concurrent stores to other processors. 
     
     
         4 . The computer program product of  claim 1 , wherein the method further comprises:
 determining whether the processor is in transactional execution mode;   based on the processor being in the transactional execution mode, determining whether the transaction is a constrained transaction or a nonconstrained transaction; and   based on the transaction being a nonconstrained transaction, continuing execution of the machine instruction.   
     
     
         5 . The computer program product of  claim 4 , wherein based on the transaction being a constrained transaction, providing a program exception and terminating execution of the machine instruction. 
     
     
         6 . The computer program product of  claim 4 , wherein based on the processor not being in transactional execution mode, executing the machine instruction as a store instruction. 
     
     
         7 . The computer program product of  claim 1 , wherein the second operand is formed from a combination of contents of a register specified by an index field of the machine instruction, contents of a register specified by a base field of the machine instruction, and contents of at least one displacement field. 
     
     
         8 . The computer program product of  claim 1 , wherein the machine instruction comprises a nontransactional store instruction, and wherein the method further comprises:
 initiating the transaction based on execution of a transaction begin instruction, the transaction effectively delaying committing transactional stores to main memory until completion of a selected transaction;   committing the transactional stores to main memory based on executing a transaction end instruction that completes execution of the selected transaction;   discarding the transactional stores based on an abort that ends execution of the selected transaction; and   wherein the nontransactionally placing is performed independent of the committing or the discarding.   
     
     
         9 . The computer program product of  claim 1 , wherein the first operand comprises contents of a register specified by the machine instruction, the contents being user-specified. 
     
     
         10 . The computer program product of  claim 1 , wherein the transaction is a nonconstrained transaction in a nesting of nonconstrained transactions. 
     
     
         11 . A computer system for executing an instruction within a computing environment, said computer system comprising:
 a memory; and   a processor in communications with the memory, wherein the computer system is configured to perform a method, said method comprising:
 obtaining, by a processor, a machine instruction for execution, the machine instruction being defined for computer execution according to a computer architecture, the machine instruction comprising:
 an operation code to specify a nontransactional store operation; 
 a first operand; and 
 a second operand to designate a location for the first operand; and 
 
 executing, by the processor, the machine instruction, the executing comprising:
 nontransactionally placing the first operand at the location specified by the second operand, wherein information stored at the second operand is retained despite an abort of a transaction associated with the machine instruction, and wherein the nontransactionally placing is delayed until an end of transactional execution mode of the processor. 
 
   
     
     
         12 . The computer system of  claim 11 , wherein multiple nontransactional stores appear as concurrent stores to other processors. 
     
     
         13 . The computer system of  claim 11 , wherein the method further comprises:
 determining whether the processor is in transactional execution mode;   based on the processor being in the transactional execution mode, determining whether the transaction is a constrained transaction or a nonconstrained transaction; and   based on the transaction being a nonconstrained transaction, continuing execution of the machine instruction.   
     
     
         14 . The computer system of  claim 13 , wherein based on the transaction being a constrained transaction, providing a program exception and terminating execution of the machine instruction. 
     
     
         15 . The computer system of  claim 13 , wherein based on the processor not being in transactional execution mode, executing the machine instruction as a store instruction. 
     
     
         16 . The computer system of  claim 11 , wherein the first operand comprises contents of a register specified by the machine instruction, the contents being user-specified, and wherein the second operand is formed from a combination of contents of a register specified by an index field of the machine instruction, contents of a register specified by a base field of the machine instruction, and contents of at least one displacement field. 
     
     
         17 . The computer system of  claim 11 , wherein the transaction is a nonconstrained transaction in a nesting of nonconstrained transactions. 
     
     
         18 - 20 . (canceled)