Entering protected pipeline mode with clearing

1. A method for executing a plurality of instructions by a processor, the method comprising:

receiving a first instruction for execution on an instruction execution pipeline while the instruction execution pipeline is in an unprotected execution mode;

beginning execution of the first instruction on the instruction execution pipeline in the unprotected execution mode;

during the execution of the first instruction, receiving an execution mode instruction to switch the instruction execution pipeline to a protected execution mode;

switching the instruction execution pipeline to the protected execution mode based on the received execution mode instruction;

annulling the first instruction based on the execution mode instruction;

receiving a second instruction for execution on the instruction execution pipeline, while the instruction execution pipeline is in the protected execution mode ; and

executing the second instruction on the instruction execution pipeline.

2. The method of claim 1 , wherein the first instruction is configured to output a result to a first memory location.

3. The method of claim 2 , wherein annulling the first instruction comprises not outputting the result to the first memory location.

4. The method of claim 1 , wherein annulling the first instruction comprises at least one of stopping execution of the first instruction, or discarding a result of the first instruction.

5. The method of claim 1 , wherein the first instruction comprises an epilog collapsed instruction.

6. The method of claim 1 , wherein the first instruction is configured to utilize a memory location, wherein the second instruction is configured to utilize the memory location, and wherein the instruction execution pipeline is configured to stall the second instruction when the second instruction uses a same memory location as the first instruction, and wherein annulling the first instruction comprises configuring the instruction execution pipeline to not stall the second instruction.

7. The method of claim 1 , wherein the first instruction is associated with a loop and the execution mode instruction is associated with an early exit of the loop.

8. A processor, comprising:

an instruction execution pipeline having a plurality of pipeline stages; and

pipeline circuitry configured to:

receive a first instruction for execution on an instruction execution pipeline while the instruction execution pipeline is in an unprotected execution mode;

begin execution of the first instruction on the instruction execution pipeline in the unprotected execution mode;

during the execution of the first instruction, receive an execution mode instruction to switch the instruction execution pipeline to a protected execution mode;

switch the instruction execution pipeline to the protected execution mode based on the received execution mode instruction;

annul the first instruction based on the execution mode instruction;

receive a second instruction for execution on the instruction execution pipeline, the second instruction; and

execute the second instruction on the instruction execution pipeline.

9. The processor of claim 8 , wherein the first instruction is configured to output a result to a first memory location.

10. The processor of claim 9 , wherein annulling the first instruction comprises not outputting the result to the first memory location.

11. The processor of claim 8 , wherein annulling the first instruction comprises at least one of stopping execution of the first instruction, or discarding a result of the first instruction.

12. The processor of claim 8 , wherein the first instruction comprises an epilog collapsed instruction.

13. The processor of claim 8 , wherein the first instruction is configured to utilize a memory location, wherein the second instruction is configured to utilize the memory location, and wherein the instruction execution pipeline is configured to stall the second instruction when the second instruction uses a same memory location as the first instruction , and wherein annulling the first instruction comprises configuring the instruction execution pipeline to not stall the second instruction.

14. A processing system comprising:

a memory; and

a processor comprising:

an instruction execution pipeline having a plurality of pipeline stages; and

pipeline circuitry configured to:

receive a first instruction for execution on an instruction execution pipeline while the instruction execution pipeline is in a first execution mode;

begin execution of the first instruction on the instruction execution pipeline in the first execution mode;

during the execution of the first instruction, receive an execution mode instruction to switch the instruction execution pipeline to a second execution mode;

switch the instruction execution pipeline to the second execution mode based on the received execution mode instruction;

annul the first instruction based on the execution mode instruction;

receive a second instruction for execution on the instruction execution pipeline, while the instruction execution pipeline is in the second execution mode; and

execute the second instruction on the instruction execution pipeline.

15. The processing system of claim 14 , wherein the first execution mode comprises an unprotected mode and the second execution mode comprises a protected mode.

16. The processing system of claim 14 , wherein the first instruction is configured to output a result to a first memory location.

17. The processing system of claim 16 , wherein annulling the first instruction comprises not outputting the result to the first memory location.

18. The processing system of claim 14 , wherein annulling the first instruction comprises at least one of stopping execution of the first instruction, or discarding a result of the first instruction.

19. The processing system of claim 14 , wherein the first instruction comprises an epilog collapsed instruction.