摘要:
A mechanism is provided for issuing instructions. An instruction dispatch unit receives an instruction for dispatch to one of a plurality of execution units. The instruction dispatch unit analyzes a tag register to determine whether a previous tag associated with a previous instruction has been stored in the tag register. Responsive to the previous tag associated with the previous instruction failing to be stored in the tag register, the instruction dispatch unit storing a tag corresponding to the instruction in the tag register. The instruction dispatch unit dispatches the instruction to an issue queue for issue to the one of the plurality of execution units.
摘要:
A mechanism is provided for issuing instructions. An instruction dispatch unit receives an instruction for dispatch to one of a plurality of execution units. The instruction dispatch unit analyzes a tag register to determine whether a previous tag associated with a previous instruction has been stored in the tag register. Responsive to the previous tag associated with the previous instruction failing to be stored in the tag register, the instruction dispatch unit storing a tag corresponding to the instruction in the tag register. The instruction dispatch unit dispatches the instruction to an issue queue for issue to the one of the plurality of execution units.
摘要:
A processor having a dependency matrix comprises a first array comprising a plurality of cells arranged in a plurality of columns and a plurality of rows. Each row represents an instruction in a processor execution queue and each cell represents a dependency relationship between two instructions in the processor execution queue. A first latch couples to the first array and comprises a first bit, the first bit indicating a first status. A second latch couples to the first array and comprises a second bit, the second bit indicating a second status. A first read port couples to the first array, comprising a first read wordline and a first read bitline. The first read wordline couples to the first latch and a first column and asserts a first available signal based on the first bit. The first read bitline couples to a first row and generates a first ready signal based on the first available signal and a first cell. A second read port couples to the first array and comprises a second read wordline and a second read bitline. The second read wordline couples to the second latch and the first column and asserts a second available signal based on the second bit. The second read bitline couples to the first row and generates a second ready signal based on the second read wordline and the first cell.
摘要:
A processor having a dependency matrix comprises a first array comprising a plurality of cells arranged in a plurality of columns and a plurality of rows. Each row represents an instruction in a processor execution queue and each cell in the first array represents a dependency relationship between two instructions in the processor execution queue. A clear port couples to the first array and clears a column of the first array. A producer status module couples to the clear port and the first array and determines an execution status of a producer instruction, wherein the producer instruction is an instruction in the processor execution queue. An available-status port couples to the first array and the producer status module and sets a read wordline column corresponding to the producer instruction based on the execution status of the producer instruction. The available-status port deasserts the read wordline column in response to a selection of the producer for execution. The available-status port reasserts the read wordline column in the event the producer status module determines the producer instruction has been rejected. The clear port clears the column of the first array corresponding to the producer instruction in the event the producer status module determines the producer instruction has been executed.
摘要:
A method for double-issue complex instructions receives a complex instruction comprising a first portion and a second portion. The method sets a single issue queue slot and allocates an execution unit for the complex instruction, and identifies dependencies in the first and second portions. The method sets a dependency matrix slot and a consumers table slot for the first and section portion. In the event the first portion dependencies have been satisfied, the method issues the first portion and then issues the second portion from the single issue queue slot. In the event the second portion dependencies have not been satisfied, the method cancels the second portion issue.
摘要:
A method receives a complex instruction comprising a first portion and a second portion. The method sets a single issue queue slot and allocates an execution unit for the complex instruction, and identifies dependencies in the first and second portions. The method sets a dependency matrix slot and a consumers table slot for the first and section portion. In the event the first portion dependencies have been satisfied, the method issues the first portion and then issues the second portion from the single issue queue slot. In the event the second portion dependencies have not been satisfied, the method places the second portion into a side issue queue. The method issues the second portion when the side issue queue indicates that the second portion is eligible for issue.
摘要:
A system and method for issuing load-dependent instructions in an issue queue in a processing unit. A load miss queue is provided. The load miss queue comprises a physical address field, an issue queue position field, a valid identifier field, a source identifier field, and a data type field. A load instruction that misses a first level cache is dispatched, and both the physical address field and the data type field are set. A load-dependent instruction is identified. In response to identifying the load-dependent instruction, each of the issue queue position field, valid identifier field, and source identifier field are set. If the issue queue position field refers to a flushed instruction, the valid identifier field is cleared. The load instruction is recycled, and a value of the valid identifier field is determined. The load-dependent instruction is then selected for issue on a next processing cycle independent of an age of the load-dependent instruction.
摘要:
A mechanism is provided for tracking deallocated load instructions. A processor detects whether a load instruction in a set of instructions in an issue queue has missed. Responsive to a miss of the load instruction, an instruction scheduler allocates the load instruction to a load miss queue and deallocates the load instruction from the issue queue. The instruction scheduler determines whether there is a dependence entry for the load instruction in an issue queue portion of a dependence matrix. Responsive to the existence of the dependence entry for the load instruction in the issue queue portion of the dependence matrix, the instruction scheduler reads data from the dependence entry of the issue queue portion of the dependence matrix that specifies a set of dependent instructions that are dependent on the load instruction and writes the data into a new entry in a load miss queue portion of the dependence matrix.
摘要:
A system and method for issuing load-dependent instructions from an issue queue in a processing unit in a data processing system. In response to a LSU determining that a load request from a load instruction missed a first level in a memory hierarchy, a LMQ allocates a load-miss queue entry corresponding to the load instruction. The LMQ associates at least one instruction dependent on the load request with the load-miss queue entry. Once data associated with the load request is retrieved, the LMQ selects at least one instruction dependent on the load request for execution on the next cycle. At least one instruction dependent on the load request is executed and a result is outputted.
摘要:
A method for double-issue complex instructions receives a complex instruction comprising a first portion and a second portion. The method sets a single issue queue slot and allocates an execution unit for the complex instruction, and identifies dependencies in the first and second portions. The method sets a dependency matrix slot and a consumers table slot for the first and section portion. In the event the first portion dependencies have been satisfied, the method issues the first portion and then issues the second portion from the single issue queue slot. In the event the second portion dependencies have not been satisfied, the method cancels the second portion issue.