Method and system for selective early release of physical registers based on a release field value in a scheduler

A computer system, comprising:

• a processor;
• and
• a memory coupled to the processor and storing instructions which, when executed by the processor, cause the processor to perform a method, the method comprising:
• determining a consumer instruction associated with a logical register identifier and one or more operands with values output by one or more prior producer instructions;
• allocating, in a register alias table entry, a physical register identifier for the logical register identifier;
• creating, in a scheduler data structure, a first entry for the consumer instruction, wherein the first entry includes:
• a scheduler entry identifier for the consumer instruction;
• the allocated physical register identifier;
• a checkpoint identifier;
• one or more scheduler entry identifiers for the one or more prior producer instructions;
• and a release field which indicates whether to early release a physical register corresponding to the allocated physical register identifier;
• updating the register alias table entry to include the scheduler entry identifier for the consumer instruction and the checkpoint identifier associated with the consumer instruction;
• receiving, by the scheduler from the register alias table, a respective scheduler entry identifier for a respective prior producer instruction and a checkpoint identifier associated with the respective prior producer instruction;
• and
• responsive to determining that the received checkpoint identifier associated with the respective prior producer instruction does not match the checkpoint identifier associated with the consumer instruction, setting, in a second entry in the scheduler data structure for the respective prior producer instruction, a release field to indicate that a physical register associated with the respective prior producer instruction is to remain allocated.

A non-transitory computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method, the method comprising:

• determining a consumer instruction associated with a logical register identifier and one or more operands with values output by one or more prior producer instructions;
• allocating, in a register alias table entry, a physical register identifier for the logical register identifier;
• creating, in a scheduler data structure, a first entry for the consumer instruction, wherein the first entry includes:
• a scheduler entry identifier for the consumer instruction;
• the allocated physical register identifier;
• a checkpoint identifier;
• one or more scheduler entry identifiers for the one or more prior producer instructions;
• and a release field which indicates whether to early release a physical register corresponding to the allocated physical register identifier;
• updating the register alias table entry to include the scheduler entry identifier for the consumer instruction and the checkpoint identifier associated with the consumer instruction;
• receiving, by the scheduler from the register alias table, a respective scheduler entry identifier for a respective prior producer instruction and a checkpoint identifier associated with the respective prior producer instruction;
• and
• responsive to determining that the received checkpoint identifier associated with the respective prior producer instruction does not match the checkpoint identifier associated with the consumer instruction, setting, in a second entry in the scheduler data structure for the respective prior producer instruction, a release field to indicate that a physical register associated with the respective prior producer instruction is to remain allocated.