Abstract: Systems, apparatuses, and methods related to a block-based processor core topology register are disclosed. In one example of the disclosed technology, a processor can include a plurality of block-based processor cores for executing a program including a plurality of instruction blocks. A respective block-based processor core can include a sharable resource and a programmable composition topology register. The programmable composition topology register can be used to assign a group of the physical processor cores that share the sharable resource.

Abstract: Apparatus and methods are disclosed for decoding targets from an instruction and transmitting data to those targets in accordance with a current instruction. Multimodal target hardware is used in conjunction with one or more of the routers so as to route data to an appropriate target. The data can be one or more operands or a predicate and the targets can include operand buffers, broadcast channels, and general registers. In this way, operands, for example, can be directed for use with multiple subsequent instructions, and there are multiple modes for distributing the operands to the multiple instructions.

Abstract: Apparatus and methods are disclosed for example computer processors that are based on a hybrid dataflow execution model. In particular embodiments, a processor core in a block-based processor comprises: one or more functional units configured to perform functions using one or more operands; an instruction window comprising buffers configured to store individual instructions for execution by the processor core, the instruction window including one or more operand buffers for an individual instruction configured to store operand values; a control unit configured to execute the instructions in the instruction window and control operation of the one or more functional units; and a broadcast value store comprising a plurality of buffers dedicated to storing broadcast values, each buffer of the broadcast value store being associated with a respective broadcast channel from among a plurality of available broadcast channels.

Abstract: Apparatus and methods are disclosed for example computer processors that are based on a hybrid dataflow execution model. Embodiments of the disclosed technology use read instructions to retrieve a value from a specified register in the register file of the processor architecture and send the value for use by one or more targets (e.g., other instructions in the instruction block). The read instruction may be predicated such that the instruction is only executed when a predicate condition is satisfied. In some examples of the disclosed technology, a compiler for such processors performs an analysis of the source and/or object code being compiled in order to determine whether operation(s) along conditional paths can be executed before or concurrently with determination of a condition on which the conditional operation(s) depend, thus improving processor efficiency.

Abstract: Apparatus and methods are disclosed for nullifying memory store instructions and one or more registers identified in a target field of a nullification instruction. In some examples of the disclosed technology, an apparatus can include memory and one or more block-based processor cores configured to fetch and execute a plurality of instruction blocks. One of the cores can include a control unit configured, based at least in part on receiving a nullification instruction, to obtain an instruction identification for a memory access instruction of a plurality of memory access instructions and a register identification of at least one of a plurality of registers, based on a first and second target fields of the nullification instruction. The at least one register and the memory access instruction associated with the instruction identification are nullified. Based on the nullified memory access instruction, a subsequent memory access instruction is executed.

Abstract: Apparatus and methods are disclosed for controlling execution of memory access instructions in a block-based processor architecture using a hardware structure that generates a relative ordering of memory access instruction in an instruction block. In one example of the disclosed technology, a method of executing an instruction block having a plurality of memory load and/or memory store instructions includes decoding an instruction block encoding a plurality of memory access instructions and generating data indicating a relative order for executing the memory access instructions in the instruction block and scheduling operation of a portion of the instruction block based at least in part on the relative order data. In some examples, a store vector data register can store the generated relative ordering data for use in subsequent instances of the instruction block.

Abstract: Apparatus and methods are disclosed for nullifying one or more registers identified in a target field of a nullification instruction. In some examples of the disclosed technology, an apparatus can include memory and one or more block-based processor cores configured to fetch and execute a plurality of instruction blocks. One of the cores can include a control unit configured, based at least in part on receiving a nullification instruction, to obtain a register identification of at least one of a plurality of registers, based on a target field of the nullification instruction. A write to the at least one register associated with the register identification is nullified. The nullification instruction is in a first instruction block of the plurality of instruction blocks. Based on the nullified write to the at least one register, a subsequent instruction is executed from a second, different instruction block.

Abstract: Systems and methods are disclosed for supporting debugging of programs in block-based processor architectures. In one example of the disclosed technology, a processor includes a block-based processor core for executing an instruction block comprising an instruction header and a plurality of instructions. The block-based processor core includes execution control logic and core state access logic. The execution control logic can be configured to schedule respective instructions of the plurality of instructions for execution in a dynamic order during a default execution mode and to schedule the respective instructions for execution in a static order during a debug mode. The core state access logic can be configured to read intermediate states of the block-based processor core and to provide the intermediate states outside of the block-based processor core during the debug mode.

Abstract: Distinct system registers for logical processors are disclosed. In one example of the disclosed technology, a processor includes a plurality of block-based physical processor cores for executing a program comprising a plurality of instruction blocks. The processor also includes a thread scheduler configured to schedule a thread of the program for execution, the thread using the one or more instruction blocks. The processor further includes at least one system register. The at least one system register stores data indicating a number and placement of the plurality of physical processor cores to form a logical processor. The logical processor executes the scheduled thread. The logical processor is configured to execute the thread in a continuous instruction window.

Abstract: Apparatus and methods are disclosed for initiating instruction block execution using a register access instruction (e.g., a register Read instruction). In some examples of the disclosed technology, a block-based computing system can include a plurality of processor cores configured to execute at least one instruction block. The at least one instruction block encodes a data-flow instruction set architecture (ISA). The ISA includes a first plurality of instructions and a second plurality of instructions. One or more of the first plurality of instructions specify at least a first target instruction without specifying a data source operand. One or more of the second plurality of instructions specify at least a second target instruction and a data source operand that specifies a register.

Abstract: Apparatus and methods are disclosed for generating and using block branch metadata in block-based processor architectures. In one example of the disclosed technology, a block-based processor is configured to dynamically generate metadata representing control flow, exit points, and control flow probabilities for an instruction block while decoding and executing the block. The metadata can be used with subsequent invocations of the instruction block for branch and memory dependence predictions. In some examples, an incomplete portion of a control flow representation is generated for a number of predicated instructions and stored in a memory or storage device for enhancing prediction and prefetch for subsequent invocations of an instruction block.

Abstract: Apparatus and methods are disclosed for controlling execution of memory access instructions in a block-based processor architecture using an instruction decoder that decodes instructions having variable numbers of target operands. In one example of the disclosed technology, a block-based processor core includes an instruction decoder configured to decode target operands for an instruction in an instruction block, the instruction being encoded to allow for a variable number of target operands and a control unit configured to send data for at least one of the decoded target operands for an operation performed by the at least one of the cores. In some examples, the instruction indicates target instructions with a vector encoding. In other examples, a variable length format allows for the indication of one or more targets.

Abstract: Apparatus and methods are disclosed for controlling instruction flow in block-based processor architectures. In one example of the disclosed technology, an instruction block address register stores an index address to a memory storing a plurality of instructions for an instruction block, the indexed address being inaccessible when the processor is in one or more unprivileged operational modes, one or more execution units configured to execute instructions for the instruction block, and a control unit configured to fetch and decode two or more of the plurality of instructions from the memory based on the indexed address.

Abstract: Systems and methods are disclosed for fetching and decoding instructions in block-based processor architectures. In one example of the disclosed technology, a block-based processor core can be used for executing an instruction block. The instruction block can include an instruction header and one or more instructions. The block-based processor core can include header decode logic and fetch logic that are in communication with each other. The header decode logic can be configured to decode the instruction block header to determine starting positions of a plurality of sub-blocks within the instruction block. The fetch logic can be configured to initiate parallel fetch and decode operations for the plurality of sub-blocks.

Abstract: Apparatus and methods are disclosed for performing memory operations instructions in a block-based processor architecture. In certain examples of the disclosed technology, a block-based processor core coupled to memory includes a control unit configured to issue one or more memory operations encoded in an instruction block allocated to the core and to commit the core when execution of the instruction block is complete, a memory store queue configured to cache one or more operands for the one or more memory operations, where a result of performing the memory operations is not architecturally visible unless the instruction block is committed by the control unit, and a memory interface configured to store the cached operands in the memory responsive to the instruction block committing. In some examples, the block-based processor core supports memory synchronization using load linked and store conditional instructions.

Abstract: Apparatus and methods are disclosed for configuring, operating, and compiling code for, block-based processor architectures. In one example of the disclosed technology, a block-based processor includes processor cores configured to decode an instruction block header for a block-based processor instruction block including one or more fields and configure at least one of the cores to execute instructions in the instruction block according to a mode of operation specified by at least one of the fields, the modes including one or more of the following: core fusion operation, vector mode operation, memory dependence prediction operation, and/or deterministic order of execution.

Abstract: Technology related to prefetching data associated with predicated stores of programs in block-based processor architectures is disclosed. In one example of the disclosed technology, a processor includes a block-based processor core for executing an instruction block comprising a plurality of instructions. The block-based processor core includes decode logic and prefetch logic. The decode logic is configured to detect a predicated store instruction of the instruction block. The prefetch logic is configured to calculate a target address of the predicated store instruction and initiate a memory operation associated with the calculated target address before a predicate of the predicated store instruction is calculated.

Abstract: Systems, apparatuses, and methods related to a block-based processor core composition register are disclosed. In one example of the disclosed technology, a processor can include a plurality of block-based processor cores for executing a program including a plurality of instruction blocks. A respective block-based processor core can include one or more sharable resources and a programmable composition control register. The programmable composition control register can be used to configure which resources of the one or more sharable resources are shared with other processor cores of the plurality of processor cores.

Abstract: Apparatus and methods are disclosed for dynamic nullification of memory access instructions, such as memory store instructions. In some examples of the disclosed technology, an apparatus can include memory and one or more block-based processor cores. One of the cores can include an execution unit configured to execute memory access instructions comprising a plurality of memory load and/or memory store instructions contained in an instruction block. The core can also include a hardware structure storing data for at least one predicate instruction in the instruction block, the data identifying whether one or more of the memory store instructions will issue if a condition of the predicate instruction is satisfied. The core may further include a control unit configured to control issuing of the memory access instructions to the execution unit based at least in a part on the hardware structure data.

Abstract: A processor is described herein that is configured to switch between a first instruction issue mode of the processor and a second instruction issue mode of the processor based at least in part on a characteristic associated with a plurality of instructions. The first instruction issue mode and the second instruction issue mode are associated with different energy consumption characteristics. Also, the first instruction issue mode may be an out-of-order instruction issue mode and the second instruction issue mode may be an in-order instruction issue mode.