Abstract: A reach matrix scheduler circuit for scheduling instructions to be executed in a processor is disclosed. The scheduler circuit includes an N×R matrix wake-up circuit, where ‘N’ is the instruction window size of the scheduler circuit, and ‘R’ is the “reach” within the instruction window of the matrix wake-up circuit, with ‘R’ being less than ‘N’. A grant line associated with each instruction request entry in the N×R matrix wake-up circuit is coupled to ‘R’ other instruction entries among the ‘N’ instruction entries. When a producer instruction in an instruction request entry is ready for issuance, the grant line associated with the instruction request entry is activated so that any other instruction entries coupled to the grant line (i.e., within the “reach” of the instruction request entry) that consume the produced value generated by the producer instruction are “woken-up” and subsequently indicated as ready to be issued.

Abstract: Processors employing memory bypassing in memory data dependent instructions as a store data forwarding mechanism, and related methods. To reduce stalls of memory data dependent, load-based instructions, a memory data dependency detection circuit is configured to detect a memory hazard between a store-based instruction and a load-based instruction based on their opcodes and designation/source operands. Some store-based and load-based instructions have opcodes identifying these instructions as having respective store and load address operand types that can be compared without resolution of their respective store and load addresses. For these detected types of instructions, the memory data dependency detection circuit is configured to determine if a source operand of a load-based instruction matches a target operand of a store-based instruction to detect a memory hazard earlier in the instruction pipeline.

Abstract: Performing flush recovery using parallel walks of sliced reorder buffers (SROBs) is disclosed herein. In one exemplary embodiment, a register mapping circuit provides a rename mapping table (RMT) comprising RMT entries representing logical register number (LRN) to physical register number (PRN) mappings. The register mapping circuit also provides an SROB comprising multiple SROB slices that each corresponds to a respective LRN. Each SROB slice tracks uncommitted instructions that write to the LRN corresponding to that SROB slice, and maintains those instructions in program order with respect to each other. Upon detecting an uncommitted instruction writing to an LRN, the register mapping circuit allocates an SROB slice entry in the SROB slice corresponding to the LRN. When an pipeline flush from a target instruction occurs, the register mapping circuit restores RMT entries of the RMT to their prior mapping states based on parallel walks of the SROB slices of the SROB.

Abstract: A reach matrix scheduler circuit for scheduling instructions to be executed in a processor is disclosed. The scheduler circuit includes an N×R matrix wake-up circuit, where ‘N’ is the instruction window size of the scheduler circuit, and ‘R’ is the “reach” with the instruction window of matrix wake-up circuit, with ‘R’ being less than ‘N’. A grant line associated with each instruction request entry in the N×R matrix wake-up circuit is coupled to ‘R’ other instruction entries among the ‘N’ instruction entries. When a producer instruction in an instruction request entry is ready for issuance, the grant line associated with the instruction request entry is activated so that any other instruction entries coupled to the grant line (i.e., within the “reach” of the instruction request entry) that consume the produced value generated by the producer instruction are “woken-up” and subsequently indicated as ready to be issued.

Abstract: A register mapping circuit for recovering a register mapping state associated with a flushed instruction by traversing ROB entries from a snapshot of another register mapping state. The register mapping circuit includes a ROB control circuit, a snapshot circuit, and a register rename recovery circuit (RRRC). The ROB control circuit allocates ROB entries to instructions entering a processor pipeline, including a target ROB entry allocated to a target instruction and other ROB entries allocated to other instructions. The snapshot circuit captures snapshots of logical register-to-physical register mapping states in the rename map table in association with a subset of instructions that could be flushed. If the target instruction is flushed, the RRRC restores the rename map table register mapping state corresponding to the target instruction based on a snapshot in a ROB entry allocated to another instruction, and traverses register mapping updates in the intervening ROB entries.

Abstract: Minimizing traversal of a processor reorder buffer (ROB) for register rename map table (RMT) state recovery for interrupted instruction recovery in a processor. Instructions may execute out of order in a processor. Information about the logical register-to-physical register mapping resulting from each instruction is stored in entries in program order in the ROB. When the pipeline is interrupted by an instruction that fails to execute, changing program flow, all instructions following the interrupting instruction may be flushed from the processor pipeline. It is important to return the state of the RMT to the state that existed when the interrupting instruction entered the pipeline. To recover the RMT state in response to an interrupting instruction, register mapping information in the ROB entries is traversed to either undo the younger instructions that entered the pipeline after the interrupting instruction or replay the older instructions that entered the pipeline before the interrupting instruction.

Abstract: A load instruction, for loading a register among a set of registers, is scheduled. Associated with scheduling the load instruction, a register dependency vector, corresponding to the register, is set to a state identifying the load instruction. A consumer instruction is scheduled, having a set of operand register and a target register, the register being in the set of operand registers. A target register dependency vector, corresponding to the target register is set in the memory. Based at least in part on the register being in the set of operand registers, a value of the target register dependency vector identifies the load instruction. Optionally, upon receiving a cache miss notice associated with the load instruction, the target register dependency vector is retrieved.

Abstract: Systems and methods of handling a register file include, in a first instruction set architecture (ISA) mode assigning a first subset of tracking resources to logical registers of a first logical register subset for tracking mappings to full granularity and first lower granularity physical registers of a first physical register subset, and assigning a second subset of tracking resources to logical registers of a second logical register subset for tracking mappings to second lower granularity physical registers of the first physical register subset. The second subset of tracking resources are configured for tracking at least the logical registers of the second logical register subset mappings to physical registers of a second physical register subset in a second ISA mode, wherein the second physical register subset is available to the second ISA mode but not the first ISA mode.

Abstract: A method of processing a plurality of instructions in multiple pipeline stages within a pipeline processor is disclosed. The method partially or wholly executes a stalled instruction in a pipeline stage that has a function other than instruction execution prior to the execution stage within the processor. Partially or wholly executing the instruction prior to the execution stage in the pipeline speeds up the execution of the instruction and allows the processor to more effectively utilize its resources, thus increasing the processor's efficiency.

Abstract: A method of processing a plurality of instructions in multiple pipeline stages within a pipeline processor is disclosed. The method partially or wholly executes a stalled instruction in a pipeline stage that has a function other than instruction execution prior to the execution stage within the processor. Partially or wholly executing the instruction prior to the execution stage in the pipeline speeds up the execution of the instruction and allows the processor to more effectively utilize its resources, thus increasing the processor's efficiency.