Apparatus and method for selective control of condition code write back
DCFirst Claim
1. A microprocessor apparatus, for selectively controlling write back of condition codes, comprising:
- translation logic, for translating an extended instruction into corresponding micro instructions, wherein said extended instruction comprises;
an extended prefix, for disabling write back of the condition codes, the condition codes corresponding to a result of a prescribed operation; and
an extended prefix tag, for indicating said extended prefix, wherein said extended prefix tag is an otherwise architecturally specified opcode within an instruction set for a microprocessor; and
extended execution logic, coupled to said translation logic, for receiving said corresponding micro instructions, and for generating said result, and for disabling write back of the condition codes.
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Abstract
A microprocessor apparatus and method are provided, for selectively controlling write back of condition codes. The microprocessor apparatus has translation logic and extended execution logic. The translation logic translates an extended instruction into corresponding micro instructions. The extended instruction includes an extended prefix and an extended prefix tag. The extended prefix disables write back of the condition codes, where the condition codes correspond to a result of a prescribed operation. The extended prefix tag indicates the extended prefix, where the extended prefix tag is an otherwise architecturally specified opcode within an instruction set for a microprocessor. The extended execution logic is coupled to the translation logic. The extended execution logic receives the corresponding micro instructions, and generates the result, and disables write back of the condition codes.
58 Citations
36 Claims
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1. A microprocessor apparatus, for selectively controlling write back of condition codes, comprising:
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translation logic, for translating an extended instruction into corresponding micro instructions, wherein said extended instruction comprises;
an extended prefix, for disabling write back of the condition codes, the condition codes corresponding to a result of a prescribed operation; and
an extended prefix tag, for indicating said extended prefix, wherein said extended prefix tag is an otherwise architecturally specified opcode within an instruction set for a microprocessor; and
extended execution logic, coupled to said translation logic, for receiving said corresponding micro instructions, and for generating said result, and for disabling write back of the condition codes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An extension mechanism, for adding condition flags write back control features to an existing microprocessor instruction set, the extension mechanism comprising:
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an extended instruction, configured to direct a microprocessor to suppress write back of a subset of a plurality of condition flags, said plurality of condition flags reflecting boundary conditions of a result, said result corresponding to execution of a specified operation, wherein said extended instruction comprises a selected opcode in the existing microprocessor instruction set followed by an n-bit extended control prefix, said selected opcode indicating said extended instruction and said n-bit extended control prefix indicating said subset; and
a translator, configured to receive said extended instruction, and configured to generate a micro instruction sequence directing said microprocessor to execute said specified operation, and directing write back control logic to preclude write back of said subset following generation of said result. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. An instruction set extension apparatus, for providing selective condition codes write back capabilities to an existing microprocessor instruction set, the instruction set extension apparatus comprising:
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an escape tag, for reception by translation logic, and for indicating that accompanying parts of a corresponding instruction prescribe an extended operation to be performed by a microprocessor, wherein said escape tag is a first opcode entity within the existing microprocessor instruction set;
a codes write back specifier, coupled to said escape tag and being one of said accompanying parts, for prescribing a plurality of condition codes associated with a result of said extended operation; and
a condition codes write back controller, coupled to said translation logic, for disabling write back of said plurality of said condition codes, and for enabling write back of remaining ones of said condition codes. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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30. A method for extending a microprocessor instruction set to provide for programmable write back of result condition codes, the method comprising:
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providing an extended instruction, the extended instruction including an extended tag along with a condition codes write back prefix, wherein the extended tag is a first opcode in the microprocessor instruction set;
prescribing, via the condition codes write back prefix and remaining parts of the extended instruction, an operation to be executed, wherein write back of selected condition codes associated with a result of the operation is to be inhibited; and
executing the operation to generate the result, and inhibiting write back of the selected condition codes. - View Dependent Claims (31, 32, 33, 34, 35, 36)
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Specification