Multi-way select instructions using accumulated condition codes

• US 20030191928A1
• Filed: 03/28/2002
• Published: 10/09/2003
• Est. Priority Date: 03/28/2002
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Sheaffer, Gad
• Granted Patent: US 7,028,171 B2
• Time in Patent Office: Days
• US Class Current: 712/236
• CPC Class Codes: G06F 9/30061 Multi-way branch instructions, e.g. CASE
• CPC Class Codes: G06F 9/30094 Condition code generation, e.g. Carry, Zero flag
• CPC Class Codes: G06F 9/30181 Instruction operation extension or modification
• CPC Class Codes: G06F 9/3842 Speculative instruction execution

Abstract

The present invention relates to a method and system for providing an N-way select instruction in a processor. Specifically, a method for providing an N-way select instruction includes decoding an instruction as an N-way select instruction. The method also includes selecting at least one pair of source operands from a plurality of instruction operands using information from a plurality of parallel control registers. The method, further includes selecting a final source operand from each of the selected at least one pair of source operands, and outputting each of the selected final source operands. In general, any N-way select instruction will have M=log₂N stages of operation.

Claims

1. A method for providing a multi-way select instruction in a processor, the method comprising:

decoding an instruction as a multi-way select instruction;

selecting at least one pair of source operands from a plurality of instruction operands using information from a plurality of parallel control registers;

selecting a final source operand from each of said selected at least one pair of source operands; and

outputting each of said selected final source operands.

2. The method as defined in claim 1 wherein said decoding operation comprises:

decoding a four-way select instruction, said four-way select instruction having said plurality of instruction operands.

3. The method as defined in claim 2 wherein said selecting at least one pair of source operands operation comprises:

selecting a predetermined source operand from each of said plurality of instruction operands.

4. The method as defined in claim 3 wherein said selecting said predetermined source operand operation comprises:

selecting a first predetermined source operand from a first of said plurality of instruction operands; and

selecting a second predetermined source operand from a second of said plurality of instruction operands.

5. The method as defined in claim 4 wherein said first instruction operand includes a first source operand having a plurality of low bits from said first instruction operand and a second source operand having a plurality of high bits from said first instruction operand, said second instruction operand includes a third source operand having a plurality of low bits from said second instruction operand and a fourth source operand having a plurality of high bits from said second instruction operands.

6. The method as defined in claim 5 wherein said selecting said first predetermined source operand operation comprises:

selecting said first predetermined source operand based on a predetermined relationship between said first source operand and said second source operand.

7. The method as defined in claim 6 wherein said predetermined relationship is defined by a preset bit value in a control register.

8. The method as defined in claim 7 wherein said preset bit value is set by a prior instruction execution.

9. The method as defined in claim 5 wherein said selecting said second predetermined source operand operation comprises:

selecting said second predetermined source operand based on a predetermined relationship between said third source operand and said fourth source operand.

10. The method as defined in claim 9 wherein said predetermined relationship is defined by a preset bit value in a control register.

11. The method as defined in claim 10 wherein said preset bit value is set by a prior instruction execution.

12. The method as defined in claim 4 wherein said storing each of said selected, predetermined source operands operation comprises:

storing said first predetermined source operand; and

storing said second predetermined source operand.

13. The method as defined in claim 2 further comprising:

shifting a control register by two bits to the right, if requested by said four-way select instruction.

14. The method as defined in claim 2 wherein said selecting said final source operand operation comprises:

selecting said final source operand based on a predetermined relationship between a first predetermined source operand and a second predetermined source operand from said at least two source operands.

15. The method as defined in claim 2 wherein said outputting operation comprises:

storing said selected final source operand in a plurality of low bits in a destination register.

16. The method as defined in claim 15 wherein said predetermined relationship is defined by a preset bit value in a control register.

17. The method as defined in claim 16 wherein said preset bit value is set by a prior instruction execution.

18. The method as defined in claim 2 further comprising:

shifting a control register by one bit to the right, if requested by said four-way select instruction.

19. The method as defined in claim 2 wherein said selecting at least two source operands operation is controlled by a plurality of preset bit values stored in a first control register, said storing at least one source operand operation is controlled by a preset bit value stored in a second control register, and said first and second control registers are arranged in parallel.

20. The method as defined in claim 1 wherein said selecting at least two source operands operation occurs during a first cycle, and said selecting said one source operand and said storing each of said selected final source operands operations occur during a second cycle.

21. The method as defined in claim 1 wherein said decoding operation comprises:

decoding a four-way SIMD parallel select instruction, said four-way SIMD parallel select instruction having said plurality of instruction operands.

22. The method as defined in claim 21 wherein said selecting at least one pair of source operands operation comprises:

selecting a plurality of predetermined source operands from said plurality of instruction operands.

23. The method as defined in claim 22 wherein said selecting said plurality of predetermined source operands operation comprises:

selecting a first predetermined source operand from one of a low-bit source operand from a first of said plurality of instruction operands and a low-bit source operand from a second of said plurality of instruction operands;

selecting a second predetermined source operand from one of a high-bit source operand from said first of said plurality of instruction operands and a high-bit source operand from said second of said plurality of instruction operands;

selecting a third predetermined source operand from one of a low-bit source operand from a third of said plurality of instruction operands and a low-bit source operand from a fourth of said plurality of instruction operands; and

selecting a fourth predetermined source operand from one of a high-bit source operand from said third of said plurality of instruction operands and a high-bit source operand from said fourth of said plurality of instruction operands.

24. The method as defined in claim 23 wherein said selecting operation comprises:

selecting a first final source operand based on a predetermined relationship between a first predetermined source operand from said at least one pair of source operands and a third predetermined source operand from said at least one pair of source operands; and

selecting a second final source operand based on a predetermined relationship between a second predetermined source operand from said at least one pair of source operands and a fourth predetermined source operand from said at least one pair of source operands.

25. The method as defined in claim 21 further comprising shifting a control register by four bits to the right, if requested by said four-way SIMD parallel select instruction having a plurality of operands.

26. The method as defined in claim 21 wherein said outputting operation comprises:

storing a first of said selected final source operands in a plurality of low bits in a destination register; and

storing a second of said selected final source operands in a plurality of high bits in said destination register.

27. The method as defined in claim 21 further comprising:

shifting a control register by two bits to the right, if requested by said four-way SIMD parallel select instruction.

28. The method as defined in claim 1 wherein said decoding operation comprises:

decoding a quad 4-way select instruction, said quad 4-way select instruction having said plurality of instruction operands.

29. The method as defined in claim 28 wherein said selecting at least one pair of source operands operation comprises:

selecting two pairs of predetermined source operands from said plurality of instruction operands.

30. The method as defined in claim 29 wherein said selecting said plurality of predetermined source operands operation comprises:

selecting a first predetermined source operand from one of a low, low-bit source operand from a first of said plurality of instruction operands and a low, low-bit source operand from a second of said plurality of instruction operands;

selecting a second predetermined source operand from one of a low, high-bit source operand from said first of said plurality of instruction operands and a low, high-bit source operand from said second of said plurality of instruction operands;

selecting a third predetermined source operand from one of a high, low-bit source operand from said first of said plurality of instruction operands and a high, low-bit source operand from said second of said plurality of instruction operands;

selecting a fourth predetermined source operand from one of a high, high-bit source operand from said first of said plurality of instruction operands and a high, high-bit source operand from said second of said plurality of instruction operands;

selecting a fifth predetermined source operand from one of a low, low-bit source operand from a third of said plurality of instruction operands and a low, low-bit source operand from a fourth of said plurality of instruction operands;

selecting a sixth predetermined source operand from one of a low, high-bit source operand from said third of said plurality of instruction operands and a low, high-bit source operand from said fourth of said plurality of instruction operands;

selecting a seventh predetermined source operand from one of a high, low-bit source operand from said third of said plurality of instruction operands and a high, low-bit source operand from said fourth of said plurality of instruction operands; and

selecting an eighth predetermined source operand from one of a high, high-bit source operand from said third of said plurality of instruction operands and a high, high-bit source operand from said fourth of said plurality of instruction operands.

31. The method as defined in claim 30 wherein said selecting operation comprises:

selecting a first final source operand based on a predetermined relationship between a first predetermined source operand from said at least one pair of source operands and a fifth predetermined source operand from said at least one pair of source operands;

selecting a second final source operand based on a predetermined relationship between a second predetermined source operand from said at least one pair of source operands and a sixth predetermined source operand from said at least one pair of source operands;

selecting a third final source operand based on a predetermined relationship between a third predetermined source operand from said at least one pair of source operands and a seventh predetermined source operand from said at least one pair of source operands; and

selecting a fourth final source operand based on a predetermined relationship between a fourth predetermined source operand from said at least one pair of source operands and an eighth predetermined source operand from said at least one pair of source operands.

32. The method as defined in claim 28 further comprising shifting a control register by four bits to the right, if requested by said quad select instruction having a plurality of operands.

33. The method as defined in claim 28 wherein said outputting operation comprises:

storing a first of said selected final source operands in a plurality of low, low bits in a destination register;

storing a second of said selected final source operands in a plurality of low, high bits in said destination register;

storing a third of said selected final source operands in a plurality of high, low-bits in said destination register; and

storing a fourth of said selected final source operands in a plurality of high, high-bits in said destination register.

34. The method as defined in claim 28 further comprising:

shifting a control register by four bits to the right, if requested by said quad select instruction.

35. The method as defined in claim 1 wherein said decoding operation comprises one of:

decoding an N-way select instruction;

said N-way select instruction having said plurality of instruction operands;

decoding a dual N-way select instruction, said dual N-way select instruction having said plurality of instruction operands; and

decoding a quad N-way select instruction, said quad N-way select instruction having said plurality of instruction operands.

36. A processor, said processor comprising:

a decoder to decode an instruction as a multi-way select instruction; and

a circuit coupled to said decoder, said circuit in response to said decoded instruction to,

select at least two source operands from a plurality of instruction operands using information from a plurality of parallel control registers;

select a final source operand from each of said selected at least two source operands; and

output each of said selected final source operands.

37. The processor defined in claim 36 wherein said decoder to decode said instruction as one of:

an N-way select instruction, said N-way select instruction having said plurality of instruction operands;

a dual N-way select instruction, said dual N-way select instruction having said plurality of instruction operands; and

a quad N-way select instruction, said quad N-way select instruction having said plurality of instruction operands.

38. A computer system, said computer system comprising:

a processor; and

a machine-readable medium coupled to the processor in which is stored one or more instructions adapted to be executed by the processor, the instructions which, when executed, configure the processor to

decode an instruction as a multi-way select instruction;

select at least two source operands from a plurality of instruction operands using information from a plurality of parallel control registers;

select a final source operand from each of said selected at least two source operands; and

output each of said selected final source operands.

39. The computer system as defined in claim 38 wherein said decode operation comprises one of:

decode said instruction as an N-way select instruction, said N-way select instruction having said plurality of instruction operands;

decode said instruction as a dual N-way select instruction, said dual N-way select instruction having said plurality of instruction operands; and

decode said instruction as a quad N-way select instruction, said quad N-way select instruction having said plurality of instruction operands.

40. A machine-readable medium, said machine-readable medium having stored thereon one or more instructions adapted to be executed by a processor, the instructions which, when executed, configure the processor to:

decode an instruction as a multi-way select instruction;

select at least two source operands from a plurality of instruction operands using information from a plurality of parallel control registers;

select a final source operand from each of said selected at least two source operands; and

output each of said selected final source operands.

41. The machine-readable medium as defined in claim 40 wherein said decode operation comprises one of:

decode said instruction as an N-way select instruction, said N-way select instruction having said plurality of instruction operands;

decode said instruction as a dual N-way select instruction, said dual N-way select instruction having said plurality of instruction operands; and

decode said instruction as a quad N-way select instruction, said quad N-way select instruction having said plurality of instruction operands.