Abstract: Explicit software control is used for data speculations. The explicit software control is applied at selected locations in a computer program to provide the benefit of data speculation while eliminating the need for hardware to perform data speculation. A computer-based method first determines, via explicit software control, whether data speculation for an item, a variable, a pointer, an address, etc., is needed. Upon determining that data speculation for the item is needed, the data speculation is performed under explicit software control. Conversely, if the explicit software control determines that data speculation is not needed, e.g., the value of the item typically obtained by execution of a long latency instruction, is available, an original code segment is executed using an actual value of the item.

Abstract: Software instructions in a single thread code sequence with a helper subthread are executed on a processor of a computer system. The execution causes the computer system, for example, to (i) determine whether information associated with a long latency instruction is available, and when the data is unavailable, to (ii) snapshot a state of the computer system and maintain a capability to roll back to that snapshot state, (iii) execute the helper instruction in the helper subthread, and (iv) roll back to the snapshot state upon completion of execution of the helper instructions in the helper subthread and continue execution. The helper subthread, for example prefetches data while waiting for the long latency instruction to complete.