摘要:
A load store pipeline 18 includes an issue queue 20 and load store circuitry 24. The load store circuitry 24 includes the plurality of access slot circuits 26 to 40. Dependency tracking circuitry 42, 44, 46, 48 serves to track a freeable number of access slot circuits 26 to 42 corresponding to the sum of access slot circuits that are empty and those processing data access instructions which have not bypassed any preceding data access instructions within the program execution order.
摘要:
An apparatus and method includes execution circuitry including a wide operand execution unit configured to allow up to N bits of operand data to be processed during execution of a single instruction. Decoder circuitry decodes and generates, for each instruction, at least one control data block identifying an operation to be performed by the execution circuitry and at least two re-combineable control data blocks for the instruction. Issue queue control circuitry then allocates a slot in the issue queue for each of the at least two data blocks and up to M bits of associated operand data, and marks those allocated slots to identify that they contain re-combineable control data blocks. The issue queue control circuitry issues the combined block to said wide operand execution unit along with the operand data contained in each of the allocated slots for said at least two control data blocks.
摘要:
A data processing apparatus executes call instructions, and after a sequence of instructions executed in response to a call instruction a return instruction causes the program flow to return to a point in the program sequence associated with that call instruction. The data processing apparatus is configured to speculatively execute instructions in dependence on a predicted outcome of earlier instructions and a return address prediction unit is configured to store return addresses associated with unresolved call instructions. The return address prediction unit comprises: a stack portion onto which return addresses associated with unresolved call instructions are pushed, and from which a return address is popped when a return instruction is speculatively executed; and a buffer portion which stores an entry for each unresolved call instruction executed and for each return instruction which is speculatively executed.
摘要:
A data processing apparatus is provided in which a processor unit accesses data values stored in a memory and a cache stores local copies of a subset of the data values. The cache maintains a status value for each local copy stored in the cache. When the processor unit executes a load-exclusive operation, a first data value is loaded from a specified memory location and an exclusive use monitor begins monitoring the specified memory location for accesses. When the processor unit executes a store-exclusive operation, a second data value is stored to the specified memory location if the exclusive use monitor indicates that the first data value has not been modified since the load-exclusive operation was executed. When a local copy of the first data value is stored in the cache and the status value for the local copy of the first data value indicates that the processor unit has exclusive usage of the first data value, the data processing apparatus is configured to prevent modification of the status value for a predetermined time period after the processor unit has executed the load-exclusive operation.
摘要:
A load store pipeline 18 includes an issue queue 20 and load store circuitry 24. The load store circuitry 24 includes the plurality of access slot circuits 26 to 40. Dependency tracking circuitry 42, 44, 46, 48 serves to track a freeable number of access slot circuits 26 to 42 corresponding to the sum of access slot circuits that are empty and those processing data access instructions which have not bypassed any preceding data access instructions within the program execution order.