Determining maximum number of live registers by recording relevant events of the execution of a computer program

An article of manufacture comprising a program storage medium having computer readable program code embodied therein for determining the maximum number of live registers in a computer system, said computer system having an executing computer program having at least one instruction that accesses said registers, wherein a read instruction is included in said instructions, said live registers being associated with said read instruction, and wherein events in said computer program are associated with said instructions, thereby associating said accessed registers with said events and said partition, comprising:

• computer readable code for identifying a number of accessed registers associated with said event that are live, and representing the number of live registers by a number_of_live_registers variable;
• computer readable code for identifying a number of accessed registers about which information is known, and representing the number of accessed registers about which information is known by a registers_with_known_information variable;
• computer readable code for identifying said partition associated with said event and representing said partition by a partition variable associated with said event;
• computer readable code for recording a register pressure information value associated with said event, said register pressure information value associated with said event including:
• (i) a number_of_live_registers variable that represents a number of said accessed registers associated with said event that are live;
• (ii) a registers_with_known_information value that represents a number of said accessed registers associated with said event about which information is known;
• and
• (iii) a partition variable that represents a partition associated with said event
• when said registers_with_known_information variable represents registers that have not previously been touched with respect to said event;
• computer readable code for retaining a previously recorded register pressure information variable when a registers with_known_information variable associated with said previously recorded register pressure information variable is equivalent to said registers_with_known_information variable included in said pressure information variable associated with said event;
• computer readable code for retaining a register pressure information variable with a largest value of said number_of_live_registers variable when
• (i) said number_of_live_registers variable has a different value than a number_of_live_registers variable included in a retained previously recorded register pressure information variable;
• and
• (ii) said registers_with_known_information variable is equivalent to a registers_with known_information variable of said retained previously recorded register pressure information variable;
• computer readable code for retaining one said register pressure information variable associated with said event when a plurality of said register pressure information variables is associated with said event, and said number_of_live_registers variables and said registers_with_known_information variables included in each of said plurality of said register pressure information variables are equivalent;
• and
• computer readable code for determining a largest value of number_of_live_registers variables included in retained register pressure information variables associated with said events in said computer program and thereby identifying said maximum number of live registers in said computer system.