Abstract: A method and system are disclosed for processing instructions within a data processing system including a processor having a plurality of execution units. According to the method of the present invention, a number of instructions stored within a memory within the data processing system are retrieved from memory. A selected instruction among the number of instructions is decoded to determine if the selected instruction would be noneffective if executed by the processor. In a preferred embodiment of the present invention, noneffective instructions include instructions with invalid opcodes and instructions that would not change the value of any data register within the processor. In response to determining that the selected instruction would be noneffective if executed by the processor, the selected instruction is recoded into a specified instruction format prior to dispatching the selected instruction to one of the number of execution units.

Abstract: A method and apparatus are disclosed for managing the execution of a floating-point store instruction within a data processing system including a memory and a superscalar processor having a number of floating-point registers (FPRs). According to the present invention, multiple instructions are dispatched for execution by the processor, including a floating-point store instruction having as an operand the content of a particular FPR. A determination is made whether the particular FPR is a destination register for results of a second instruction which precedes the store instruction in program order. If so, a determination is made whether the second instruction must complete before subsequent instructions can be successfully dispatched. In response to a determination that the second instruction must be completed prior to successfully dispatching subsequent instructions, the floating-point instruction is cancelled and redispatched after the completion of the second instruction.

Abstract: A method and system within a processor are disclosed for executing selected instructions among a number of instructions stored within a memory, wherein the processor has a maximum of instructions that can dispatched for execution during each processor cycle. A subset of the instructions are fetched from the memory for execution. A determination is then made whether the set of instructions includes an unresolved branch instruction. In response to a determination that the set of instructions includes an unresolved branch instruction, a prediction is made whether a branch indicated by the branch instruction will be taken or will not be taken. In response to a prediction that the branch will be taken, a nonsequential target instruction indicated by the branch instruction is fetched from memory.

Abstract: A method and system are disclosed for processing instructions within a data processing system including a processor having a plurality of execution units. According to the method of the present invention, a number of instructions stored within a memory within the data processing system are retrieved from memory. A selected instruction among the number of instructions is decoded to determine if the selected instruction would be noneffective if executed by the processor. In a preferred embodiment of the present invention, noneffective instructions include instructions with invalid opcodes and instructions that would not change the value of any data register within the processor. In response to determining that the selected instruction would be noneffective if executed by the processor, the selected instruction is recoded into a specified instruction format prior to dispatching the selected instruction to one of the number of execution units.

Abstract: An apparatus for handling special cases outside of normal floating-point arithmetic functions is provided that is used in a floating-point unit used for calculating arithmetic functions. The floating-point unit generates an exponent portion and a mantissa portion and a writeback stage is coupled to the exponent portion and to the mantissa portion and is specifically used to handle the special cases outside the normal float arithmetic functions. A spill stage is also provided and is coupled to the writeback stage to receive a resultant exponent and mantissa. A register file unit is coupled to the writeback stage and the spill stage through a plurality of rename busses, which are used to carry results between the writeback stage and spill stage and the register file. The spill stage is serially coupled to the writeback stage so as to provide a smooth operation in the transition of operating on the results from the writeback stage for the exponent and mantissa.