Exception handling for single instructions with multiple data

• US 6,944,745 B2
• Filed: 08/26/2002
• Issued: 09/13/2005
• Est. Priority Date: 08/26/2002
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Parthasarathy, Rajesh S.
• Primary Examiner(s): Pan, Daniel H.
• Application Number:
  US10/229,317
• Publication Number:
  US 20040039902A1
• Time in Patent Office: 1,114 Days
• Field of Search: 712/22, 712/244
• US Class Current: 712/22
• CPC Class Codes: G06F 9/30036 Instructions to perform operations on packed data, e.g. vector, tile or matrix operations
• CPC Class Codes: G06F 9/30094 Condition code generation, e.g. Carry, Zero flag
• CPC Class Codes: G06F 9/3861 Recovery, e.g. branch miss-prediction, exception handling error detection or correction G06F11/00

Abstract

Processing a micro-operation may include providing information to an event handler indicating which of multiple sets of data caused events during processing of a single instruction on multiple sets of data in parallel. The event handler may access the provided information to simplify handling of data sets that did not cause an event. Handling the data sets may include the event handler determining a result for data sets that caused events, accessing results determined outside of the event handler for data sets that did not cause an event, and accumulating all of the results.

Claims

1. A method comprising:

determining a result for a non-eventing set of data, the non-eventing set of data being one of multiple sets of data, while processing a single micro-operation on the multiple sets of data in parallel;

storing the result for the non-eventing set of data;

detecting an event while processing the single micro-operation on an other of the multiple sets of data, wherein the other set is referred to as an eventing set;

providing information to an event handler about which of the multiple sets of data caused the event;

accessing, by the event handler, the provided information;

determining by the event handler a result for the eventing set of data, and

accumulating by the event handler the two results into an overall result of the single micro-operation for the multiple sets of data.

2. The method of claim 1 wherein:

determining the result for the non-eventing set of data, storing the result, and detecting the event are performed by an execution unit of a processor while processing the micro-operation, and

providing information to the event handler is performed by a retirement unit of the processor, and

the event handler comprises microcode.

3. The method of claim 2 wherein providing information to the event handler comprises routing the information from the execution unit to the retirement unit, and from the retirement unit to the event handler.

4. The method of claim 1 further comprising:

detecting a second event while processing the single micro-operation on a third of the multiple sets of data;

providing information to the event handler about which of the multiple sets of data caused the second event;

accessing by the event handler the information indicating which data set caused the second event; and

determining by the event handler a result for the third set of data, wherein accumulating comprises accumulating the three results.

5. The method of claim 1 further comprising:

providing information to the event handler indicating the type of the event; and

accessing, by the event handler, the provided event-type information.

6. The method of claim 5 wherein:

providing information indicating the type of the event comprises providing an indication that the event is a single-instruction/multiple data (“

SIMD”

) event, and

the method further comprises providing information to the event handler indicating a specific type of the SIMD event.

7. The method of claim 6 wherein providing information indicating the specific type of the SIMD event comprises providing an indication that the event is a denormal event, an invalid event, a precision event, an exponent underflow event, an exponent overflow event, or a divide by zero event.

8. The method of claim 6 wherein providing information indicating the specific type of the SIMD event comprises providing an indication that the event is a pre-assist event.

9. The method of claim 6 wherein providing information indicating the specific type of the SIMD event comprises providing an indication that the event is a post-assist event.

10. The method of claim 1 further comprising:

providing information about a source of the micro-operation to the event handler; and

accessing by the event handler the source information.

11. The method of claim 10 wherein the source information indicates that the source is from memory.

12. The method of claim 10 further comprising:

determining, by the event handler and based on the source information, a non-memory location storing data that is also referenced by the source operand; and

processing the micro-operation, by the event handler, using the non-memory location.

13. The method of claim 1 further comprising:

providing information to the event handler indicating a class of the micro-operation, the class being determinable prior to any determination that the micro-operation produces an event on a data set; and

accessing by the event handler the information indicating the class of the micro-operation.

14. The method of claim 13 wherein providing the information indicating the class comprises returning a result from an other micro-operation, the other micro-operation being part of microcode of the event handler and the other micro-operation accepting an opcode as a source operand and returning the class as the result.

15. The method of claim 13 wherein the class includes one or more of arithmetic and conversion.

16. The method of claim 13 further comprising selecting, by the event handler, a routine within the event handler based on the information indicating the class of the micro-operation.

17. The method of claim 1 wherein the provided information does not uniquely identify a particular set of data, from the multiple sets of data, as the set of data that caused the event but identifies a group of sets of data as possible sets of data that may have caused the event.

18. The method of claim 1 further comprising processing, by the event handler, each of the multiple sets of data, wherein the processing is simplified for any of the multiple sets of data that did not cause an event, compared to the processing for a set of data that did cause an event.

19. The method of claim 1 further comprising processing, by the event handler, each of the multiple sets of data serially.

20. The method of claim 1 further comprising processing, by the event handler, multiple sets of data in parallel.

21. The method of claim 1 wherein providing information to the event handler comprises returning a result from an other micro-operation, the other micro-operation being part of microcode of the event handler and returning the information about which of the multiple sets of data caused the event.

22. The method of claim 1 wherein providing information to the event handler comprises routing the information to the event handler.

23. The method of claim 1 further comprising copying the result of the non-eventing set of data to a location that can be accessed by the event handler.

24. The method of claim 1 wherein the multiple sets of data comprise four sets of data.

25. The method of claim 24, further comprising detecting events for each of the multiple sets of data while processing the multiple sets of data in parallel.

26. The method of claim 1 wherein accumulating comprising accumulating results for each of the multiple sets of data.

27. The method of claim 1 wherein:

the result for the non-eventing set of data is an arithmetic result, and

the result for the eventing set of data is an arithmetic result.

28. The method of claim 27 wherein accumulating the two arithmetic results comprises concatenating the two results into a single data location.

29. The method of claim 1 wherein:

the result for the non-eventing set of data is a flag result,

determining the flag result for the non-eventing set of data comprises determining that no flag needs to be set for the non-eventing set of data,

the result for the eventing set of data is a flag result, and

determining the flag result for the eventing set of data comprises determining that a flag needs to be set.

30. The method of claim 29 wherein accumulating the two flag results comprises bitwise ORing the two flag results.

31. The method of claim 1 wherein the overall result comprises a destination value produced by the single micro-operation after successful completion of the single micro-operation on the multiple sets of data.

32. The method of claim 31 wherein the event handler comprises a microcode portion that performs the accumulating.

33. A processor comprising:

an execution unit operable (i) to determine a result for a non-eventing set of data, the non-eventing set of data being one of multiple sets of data, while processing by a processor a single micro-operation on the multiple sets of data in parallel, (ii) to store the result for the non-eventing set of data, and (iii) to detect an event while processing the single micro-operation on another of the multiple sets of data, wherein the other set is referred to as an eventing set;

a retirement unit, in communication with the execution unit, operable to provide information to an event handler about which of the multiple sets of data caused the event; and

an event handler implemented in microcode and, when executed, able (i) to access the provided information, (ii) to determine a result for the eventing set of data, and (iii) to accumulate the two results into an overall result of the single micro-operation for the multiple sets of data.

34. The apparatus of claim 33 wherein the retirement unit is operable to provide the information to the event handler by routing a data element containing the information to the event handler.

35. The apparatus of claim 33 wherein:

the execution unit provides the event handler access to the result for the non-eventing set of data by copying the result for the non-eventing set of data to a location accessible by the event handler, and provides event type information to the retirement unit indicating that a SIMD event occurred, and

the retirement unit decodes the provided event type information to determine that a SIMD event occurred, halts execution of a program containing the micro-operation, and redirects control to the event handler that handles SIMD events.

36. A computer comprising a processor coupled to a memory wherein:

the processor includes an execution cluster, a retirement unit, and a microcode event handler,

one or more of the execution cluster and the retirement unit are operable, either collectively or individually, (i) to determine a result for a non-eventing set of data, the non-eventing set of data being one of multiple sets of data, while processing by a processor a single micro-operation on the multiple sets of data in parallel, (ii) to store the result for the non-eventing set of data, (iii) to detect an event while processing the single micro-operation on another of the multiple sets of data, wherein the other set is referred to as an eventing set, and (iv) to provide information to the event handler about which of the multiple sets of data caused the event, a type of the event, a class of the micro-operation, and a source of the micro-operation, and

the event handler, when executed by the processor, is able (i) to access the provided information, (ii) to determine a result for the eventing set of data, and (iii) to accumulate the two results into an overall result of the single micro-operation for the multiple sets of data.

37. A method of processing a micro-operation, the method comprising:

determining a result for a non-eventing set of data, the non eventing set of data being one of multiple sets of data, while processing by a processor a single micro-operation on the multiple sets of data in parallel;

storing the result for the non-eventing set of data;

detecting an event while processing the single micro-operation on another an other of the multiple sets of data, wherein the other set is referred to as an eventing set;

providing information to an event handler about which of the multiple sets of data caused the event, wherein the provided information does not uniquely identify a particular set of data, from the multiple sets of data, as the set of data that caused the event but identifies a group of sets of data as possible sets of data that caused the event;

accessing, by the event handler, the provided information;

determining by the event handler a result for the eventing set of data; and

accumulating by the event handler the two results into an overall result of the single micro-operation for the multiple sets of data.