Patent application number | Description | Published |
20150154022 | Soft-Partitioning of a Register File Cache - Soft-partitioning of a register file cache is implemented by renaming registers associated with an instruction based on which thread, in a multi-threaded out-of-order processor, the instruction belongs to. The register renaming may be performed by a register renaming module and in an embodiment, the register renaming module receives an instruction for register renaming which identifies the thread associated with the instruction and one or more architectural registers. Available physical registers are then allocated to each identified architectural register based on the identified thread. In some examples, the physical registers in the multi-threaded out-of order processor are logically divided into groups and physical registers are allocated based on a thread to group mapping. In further examples, the thread to group mapping is not fixed but may be updated based on the activity level of one or more threads in the multi-threaded out-of-order processor. | 06-04-2015 |
20150160981 | Global Register Protection In A Multi-Threaded Processor - Global register protection in a multi-threaded processor is described. In an embodiment, global resources within a multi-threaded processor are protected by performing checks, before allowing a thread to write to a global resource, to determine whether the thread has write access to the particular global resource. The check involves accessing one or more local control registers or a global control field within the multi-threaded processor and in an example, a local register associated with each other thread in the multi-threaded processor is accessed and checked to see whether it contains an identifier for the particular global resource. Only if none of the accessed local resources contain such an identifier, is the instruction issued and the thread allowed to write to the global resource. Otherwise, the instruction is blocked and an exception may be raised to alert the program that issued the instruction that the write failed. | 06-11-2015 |
20150205611 | Stack Pointer Value Prediction - Methods and apparatus for predicting the value of a stack pointer which store data when an instruction is seen which grows the stack. The information which is stored includes a size parameter which indicates by how much the stack is grown and one or both of: the register ID currently holding the stack pointer value or the current stack pointer value. When a subsequent instruction shrinking the stack is seen, the stored data is searched for one or more entries which has a corresponding size parameter. If such an entry is identified, the other information stored in that entry is used to predict the value of the stack pointer instead of using the instruction to calculate the new stack pointer value. Where register renaming is used, the information in the entry is used to remap the stack pointer to a different physical register. | 07-23-2015 |
20150205612 | Stack Saved Variable Pointer Value Prediction - Methods of predicting stack pointer values of variables stored in a stack are described. When an instruction is seen which stores a variable in the stack in a position offset from the stack pointer, an entry is added to a data structure which identifies the physical register which currently stores the stack pointer, the physical register which stores the value of the variable and the offset value. Subsequently when an instruction to load a variable from the stack from a position which is identified by reference to the stack pointer is seen, the data structure is searched to see if there is a corresponding entry which includes the same offset and the same physical register storing the stack pointer as the load instruction. If a corresponding entry is found the architectural register in the load instruction is mapped to the physical register storing the value of the variable from the entry. | 07-23-2015 |
20150220450 | Return Stack Buffer Having Multiple Address Slots Per Stack Entry - A return stack buffer (RSB) is modified such that each entry comprises two or more address slots. When a function is called, the address following the function call is pushed to the RSB and stored in a selected one of the address slots in a top entry in the RSB. One or more pointer bits within the entry are set to indicate which slot the address was stored in. | 08-06-2015 |
20150220451 | Storing Look-Up Table Indexes in a Return Stack Buffer - A return stack buffers (RSB) is modified to store index values instead of addresses. When a function is called, the address following the function call is stored in a look-up table and the index at which the address is stored is pushed to the RSB. When a function returns, an index is popped from the RSB and used to identify an address in the look-up table. In another embodiment, the RSB is modified such that each entry comprises two or more address slots. When a function is called, the address following the function call is pushed to the RSB and stored in a selected one of the address slots in a top entry in the RSB. One or more pointer bits within the entry are set to indicate which slot the address was stored in. | 08-06-2015 |
20150301863 | Allocating Resources to Threads Based on Speculation Metric - Methods, reservation stations and processors for allocating resources to a plurality of threads based on the extent to which the instructions associated with each of the threads are speculative. The method comprises receiving a speculation metric for each thread at a reservation station. Each speculation metric represents the extent to which the instructions associated with a particular thread are speculative. The more speculative an instruction, the more likely the instruction has been incorrectly predicted by a branch predictor. The reservation station then allocates functional unit resources (e.g. pipelines) to the threads based on the speculation metrics and selects a number of instructions from one or more of the threads based on the allocation. The selected instructions are then issued to the functional unit resources. | 10-22-2015 |
20150339123 | Restoring a Register Renaming Map - A technique for restoring a register renaming map is described. In one example, a restore table having a number of storage locations saves a copy of the register renaming map whenever a flow-risk instruction is passed to a re-order buffer. When all storage locations are full, further instructions still pass to the re-order buffer, but a copy of the map is not saved. A storage location subsequently becomes available when its associated flow-risk instruction is executed. A register renaming map state for an unrecorded flow-risk instruction passed to the re-order buffer whilst the storage locations were full is generated and stored in the available location. This is generated using the restore table entry for a previous flow-risk instruction and re-order buffer values for intervening instructions between the previous and unrecorded flow-risk instructions. The restore table can be used to restore the map if an unexpected change in instruction flow occurs. | 11-26-2015 |