Scheduling program instructions with a runner-up execution position

Apparatus for processing data comprising:

• a plurality of means for executing a common program as a respective plurality of threads of program execution;
• and
• means for determining a next scheduled execution position within said common program corresponding to a next program instruction to be executed by at least one of said plurality of means for executing while any of said plurality of means for executing at a current execution position in an execution path through said common program not followed by said next scheduled position do not execute said next program instruction;
• wherein
• said means for determining is configured to also calculate a runner up execution position that would have been determined as said next scheduled execution position if said next program instruction was excluded from serving as said next scheduled execution position;
• and wherein said means for determining is configured to:
• determine said next scheduled execution position so as to follow an execution path corresponding to consecutive instructions in program counter order unless a point of full determination is detected by said means for determining whereupon said means for determining is configured to perform a full determination of said next scheduled execution position that provides for one or more possible execution paths not corresponding to consecutive instructions in program counter order;
• calculate said runner up execution position upon said detection of a current point of full determination;
• and
• detect a further point of full determination if said execution path reaches said runner up execution position.

A method of processing data comprising the steps of:

• executing a common program as a respective plurality of threads of program execution with a plurality of execution circuits;
• and
• scheduling including determining a next scheduled execution position within said common program corresponding to a next program instruction to be executed by at least one of said plurality of execution circuits while any of said plurality of execution circuits at a current execution position in an execution path through said common program not followed by said next scheduled position do not execute said next program instruction;
• wherein said step of scheduling includes:
• calculating a runner up execution position that would have been determined as said next scheduled execution position if said next program instruction was excluded from serving as said next scheduled execution position;
• determining said next scheduled execution position so as to follow an execution path corresponding to consecutive instructions in program counter order unless a point of full determination is detected by said scheduling circuitry whereupon said a full determination of said next scheduled execution position is performed that provides for one or more possible execution paths not corresponding to consecutive instructions in program counter order;
• calculating said runner up execution position upon said detection of a current point of full determination;
• and
• detecting a further point of full determination if said execution path reaches said runner up execution position.