36 results about "Delay slot" patented technology

A system and method are presented for saving and restoring the state of a diagnostic module in a microprocessor. The diagnostic module contains a complex break state machine, capable of halting the microprocessor at specified breakpoints. These breakpoints are based on combinations of instruction locations and/or data values, along with previous machine states. A problem occurs with prior art diagnostic modules when the processor returns from an exception occurring during a fix-up cycle inserted to handle a data load miss associated with an instruction located in a branch delay slot (the location immediately following a conditional branch instruction). Under these circumstances, the exception handler restores the program counter to the location of the branch instruction, causing the branch to be re-executed. The prior art state machine erroneously updates its internal state a second time when the branch is re-executed. According to the system and method disclosed herein, at each state change the previous machine state saved. Thus, when a branch instruction is re-executed, the complex break state machine of the present invention is restored to its previous state, thereby correcting the error.

The invention discloses a system and a method for processing a jump instruction of a microprocessor in a branch prediction way. The system comprises a coding module and a transmission module, wherein the coding module comprises a branch predictor used for predicting by adopting a static prediction method when the jump instruction to be processed is in the jump execution type or adopting a dynamicprediction method when the jump instruction to be processed is not in the jump execution type after the coding module judges that an instruction to be processed is the jump instruction and judges thetype of the jump instruction through precoding, and directly writing the jump instruction to be processed and a delay slot instruction thereof in an operational queue in a sequence of the instructions in a program; and the transmission module comprises a prediction result processor used for canceling the instruction executed by error and continue fetching in a correct jump direction when the branch predictor predicts the jump instruction by error after the jump instruction is executed and written back to the transmission module. The system cancels operation by adopting different cancellation methods on the basis that whether the instruction is the jump execution instruction or not when the instruction is cancelled.

The invention discloses an instruction branch prediction method and system. After a current instruction is executed, instructions of a preset number to be executed in a sequential executing direction are obtained and cached, whether the first cached instruction is of a jump instruction type or not is judged, and if yes, a jump target address is calculated, and a target jump instruction is cached; when a jump condition is met, cache of the target jump instruction is directly read, the jump instruction can be executed, and if the jump condition cannot be met, the second cached instruction in the sequential executing direction is directly read; when the jump instruction is executed, due to the fact that the subsequent instructions to be executed are all obtained and can be directly read, cached and executed no matter whether the jump condition is met or not, bidirectional instruction branch prediction is achieved in a jump instruction prejudgment, instruction pre-taking, instruction cache and direct reading and caching mode, processor assembly line pauses caused by the jump instruction are eliminated, and the situation that the executing efficiency of a processor is reduced due to the fact that the processor is inserted into a branch delay clearance is avoided.

The invention discloses a method and a system for scheduling a delay slot in a very-long instruction word structure. The method comprises the steps of locally scheduling instructions in a current basic block; after the local scheduling is finished, judging whether a residual instruction delay slot exists, if not, ending the scheduling, otherwise, putting an instruction which can be filled into the instruction delay slot and is high in spending into a local standby instruction cache; globally scheduling instructions in a basic block of a branch target, selecting an instruction which can be filled into the instruction delay slot and placing the instruction in a global standby instruction cache; and selecting an instruction from the local standby instruction cache and/or the global standby instruction cache and filling the instruction into the residual instruction delay slot. The system comprises a local scheduling unit, a global scheduling unit and a balanced scheduling unit. According to the method and the system for scheduling the delay slot in the very-long instruction word structure disclosed by the invention, through balance between scheduling of the delay slot and program parallelism, as well as balance between local scheduling and global scheduling, high execution efficiency of programs can be implemented.

In correspondence with an address of a branch instruction, a branch target address Apb, a valid bit V as branch history information, and delay slot information POS on the last position of delay slot instructions are stored in a branch target buffer 241. A branch prediction circuit 23 outputs hit information H/M as to whether or not an input address Ao is coincident with the branch instruction address, the valid bit which is also a branch prediction bit, the information POS, and the branch target address Apb. When a prediction error signal ERR is inactive, the address selection circuit 22 selectively outputs the output of an incrementer 21 and the branch target address Apb, based on the hit information H/M, the delay slot information POS, and the valid bit V.

A first tag is assigned to a branch instruction. Dependent on the type of branch instruction, a second tag is assigned to an instruction in the branch delay slot of the branch instruction. If the branch is mispredicted, the first tag is broadcast to pipeline stages that may have speculative instructions, and the first tag is compared to tags in the pipeline stages to determine which instructions to cancel. The assignment of tags for a fetch group of concurrently fetched instructions may be performed in parallel. A plurality of branch sequence numbers may be generated, and one of the plurality may be selected for each instruction responsive to the cumulative number of branch instructions preceding that instruction within the fetch group. The selection may be further responsive to whether or not the instruction is in a conditional delay slot.

The invention provides a jump source list processing method, a jump source list processing device and a compiler. The jump source list processing method includes that identify of a jump target which corresponds to n jump instructions is acquired, wherein the n is a positive integer larger than or equal to 2; the identify is taken as a pointer pointing to a delay slot behind each jump instruction in the n jump instructions, and the corresponding jump instructions are stored in address information in a code buffer area when the pointer points to the delay slots. The jump instruction address information in a jump source list is stored in the delay slots, so that memory overhead caused by the fact that a special space is arranged in a memory to store the jump instruction address information of the jump source list in a list structure mode can be avoided; after the address of the jump target is determined, modification of the target address of the n jump instructions can be completed in the code buffer area through one-time traversal; compared with the prior art, the jump source list processing method has the advantages that the number of times of traversal in modifying the n jump instructions according to the address of the jump target can be reduced, and execution efficiency in improving the n instructions can be improved.

The invention discloses a processing method for calling a subprogram of a microprocessor, and a device for the same. The method comprises the following steps of: obtaining a subprogram calling instruction which carries an unsigned immediate; extracting the unsigned immediate from the subprogram calling instruction; obtaining the total number of the instructions in a delay slot according to the unsigned immediate; and obtaining the return address of the subprogram calling instruction according to the total number of the instructions in the delay slot. The device comprises the following units: an obtaining unit for obtaining the subprogram calling instruction, an extraction unit for extracting the unsigned immediate from the subprogram calling instruction, and a calculation unit for obtaining the total number of the instructions in the delay slot according to the unsigned immediate and calculating the return address of the subprogram calling instruction according to the total number of the instructions in the delay slot. According to the method and the device for the same, performance of the processor in the aspect of processing the subprogram calling instruction is greatly improved.

A first storage unit stores an address of a branching instruction and a branched address. A first detector detects whether or not an instruction of the present address has previously been branched from an output of the first storage unit. When the first detector detects previous branching of the instruction of the present address, the second storage unit stores the branched address corresponding to the address of the instruction to be executed following the branching instruction. When a second detector detects an output of a program counter as the address of the instruction to be executed following the branching instruction, the second storage unit outputs the branched address.

The invention belongs to the technical field of reconfigurable computing, particularly relates to an array processor under a dual-mode instruction set architecture, which can avoid loaduse adventure pause, and aims at solving the problem that when an existing traditional instruction set architecture faces loaduse-use adventure, the problem must be solved by a method of pausing an assembly line, and provides the following scheme that the array processor comprises an array processor body, the array processor body comprises a global controller, a processing element array, an instruction memory and a data memory, the instruction memory is connected with the global controller, the global controller is connected with the processing element array, and the processing element array is connected with the data memory. According to the array processor, a traditional branch delay slot design is not adopted, and assembly line pause or assembly line scouring cannot be generated for any existing risk, so that the design of a hardware circuit is greatly simplified, area resources are saved, the power consumption of the array processor is reduced, and the performance of the array processor is improved.

A method of managing the configuration, design parameters, and functionality of an integrated circuit (IC) design using a hardware description language (HDL). Instructions can be added, subtracted, or generated by the designer interactively during the design process, and customized HDL descriptions of the IC design are generated through the use of scripts based on the user-edited instruction set and inputs. The customized HDL description can then be used as the basis for generating 'makefiles' for purposes of simulation and/or logic level synthesis. The method further affords the ability to generate an HDL model of a complete device, such as a microprocessor or DSP. A computer program implementing the aforementioned method and a hardware system for running the computer program are also disclosed.