Abstract: An electronic device includes a memory, a processor coupled to the memory, and one or more policies stored in the memory. The policies include a resource availability policy determining whether the processor should continue evaluating the software, and a job availability policy determining whether new jobs will be created for unexplored branches. The processor is configured to receive a job to be executed, evaluate the software, select a branch to explore and store an initialization sequence of one or more unexplored branches if a branch in the software is encountered, evaluate the job availability policy, decide whether to create a job for each of the unexplored branches based on the job availability policy, evaluate the resource availability policy, and decide whether to continue evaluating the software at the branch selected to explore based on the resource availability policy. The job indicates of a portion of software to be evaluated.

Abstract: A microprogrammable electronic device comprises a code memory storing a plurality of instructions. At least one instruction, when executed by the device, causes the device to enter into a wait state associated with a plurality of predefined wait state exit conditions. The device is configured to load into an electronic table each condition together with a corresponding code memory address of an instruction to be executed when the condition occurs; to execute, when is in the wait state, a wait instruction stored in the code memory and which, when executed, is such as to cause the device to check simultaneously the conditions loaded into said electronic table to detect if condition occurs; and, if a condition occurs, to exit from said wait state and to execute the instruction stored in the code memory at the code memory address loaded into the electronic table together with the condition that occurred.

Abstract: A method for conditionally performing a SIMD operation causing a predetermined number of result objects to be held in a combination of different ones of a plurality of destination stores, the method comprising receiving and decoding instruction fields to determine at least one source store, a plurality of destination stores and at least one control store, said source and destination stores being capable of holding one or a plurality of objects, each object defining a SIMD lane. Conditional execution of the operation on a per SIMD lane basis is controlled using a plurality of pre-set indicators of the at least one control store designated in the instruction, wherein each said pre-set indicator i controls a predetermined number of result lanes p, where p takes a value greater than or equal to two. A predetermined number of result objects are sent to the destination stores such that the predetermined number of result objects are held by a combination of different ones of the plurality of destination stores.

Abstract: A microprocessor includes a pipeline of stages for processing instructions and first and second types of conditional branch instruction includable by a program. The microprocessor makes a prediction of conditional branch instructions of the first type and flushes the pipeline of instructions if the prediction is subsequently determined to be incorrect, thereby incurring a branch misprediction penalty related to processing of conditional branch instructions of the first type. The microprocessor always correctly resolves conditional branch instructions of the second type without making a prediction of conditional branch instructions of the second type, thereby avoiding ever incurring a branch misprediction penalty related to processing of conditional branch instructions of the second type.

Abstract: A method comprising receiving a branch instruction, decoding a branch address and the branch instruction, executing a branch action associated with the branch address, determining whether a branch associated with the branch action was taken, and saving an identifier of the branch instruction and in indicator that the branch action was taken in a prefetch history table responsive to determining that the branch associated with the branch action was taken.

Abstract: A test code generation technique that replaces instructions having a machine state dependent result with special redirection instructions provides generation of test code in which state dependent execution choices are made without a state model. Redirection instructions cause execution of a handler than examines the machine state and replaces the redirection instruction with a replacement instruction having a desired result resolved in accordance with the current machine state. The instructions that are replaced may be conditional branch instructions and the result a desired execution path. The examination of the machine state permits determination of a branch condition for the replacement instruction so that the next pass of the test code executes along the desired path. Alternatively, the handler can execute a jump to the branch instruction, causing immediate execution of the desired branch path.

Abstract: One embodiment of the present disclosure sets forth an optimized way to execute pre-scheduled replay operations for divergent operations in a parallel processing subsystem. Specifically, a streaming multiprocessor (SM) includes a multi-stage pipeline configured to insert pre-scheduled replay operations into a multi-stage pipeline. A pre-scheduled replay unit detects whether the operation associated with the current instruction is accessing a common resource. If the threads are accessing data which are distributed across multiple cache lines, then the pre-scheduled replay unit inserts pre-scheduled replay operations behind the current instruction. The multi-stage pipeline executes the instruction and the associated pre-scheduled replay operations sequentially. If additional threads remain unserviced after execution of the instruction and the pre-scheduled replay operations, then additional replay operations are inserted via the replay loop, until all threads are serviced.

Abstract: Embodiments related to conducting and constructing a secure start-up process are disclosed, One embodiment provides, on a computing device, a method of conducting a secure start-up process. The method comprises recognizing the branch instruction, and, in response, calculating an integrity datum of a data segment. The method further comprises obtaining an adjustment datum, and computing a branch target address based on the integrity datum and the adjustment datum.

Abstract: A method, program, and apparatus for optimizing compiled code using a dynamic compiler. The method includes the steps of: generating intermediate code from a trace, which is an instruction sequence described in machine language; computing an offset between an address value, which is a base point of an indirect branch instruction, and a start address of a memory page, which includes a virtual address referred to by the information processing apparatus immediately after processing a first instruction; determining whether an indirect branch instruction that is subsequent to the first instruction causes processing to jump to another memory page, by using a value obtained from adding the offset to a displacement made by the indirect branch instruction; and optimizing the intermediate code by using the result of the determining step.

Abstract: The present disclosure relates to a method for executing, by a processor, a program read in a program memory, comprising steps of: detecting a program memory read address jump; providing prior to a jump address instruction for jumping a program memory read address, an instruction for storing the presence of the jump address instruction; and activating an error signal if an address jump has been detected and if the presence of a jump address instruction has not been stored. The present disclosure also relates to securing integrated circuits.

Abstract: Declarations from an input source code are serialized into a stream of tokens produced by following each branch of a preprocessor conditional directive statement that interrupts a declaration. Tokens are labeled with a parsing path indicator corresponding to a parsing path induced by branches of a preprocessor conditional directive. The declarations that are formed along the different parsing paths are serialized by fetching the tokens that belong to the first parsing path in a first pass, and passing the tokens on to a next phase of a compiler. The pointer that marks the next token is repositioned to return to the start of the declaration. The declaration may be serialized again through the second parsing path in a second pass. The operation may be repeated until each of the parsing paths induced by the presence of branches of the preprocessor conditional directives in the source code is exhausted.

Abstract: A method, data processing system, and computer program product for managing a branch trace environment. In response to a branch being taken for a first branch instruction that is conditional and direct in the branch instructions, a performance monitoring unit stores an effective address of the first branch instruction into a first entry in a set of entries in a memory. The performance monitoring unit counts each branch not taken in processing the branch instructions occurring after the first branch instruction to form a branch count. In response to a branch being taken during processing of subsequent branch instructions in the branch instructions after the first branch instruction, the performance monitoring unit determines whether to create a second entry in the set of entries in the memory using the branch count with a set of rules identifying when the second entry is to be made.

Abstract: In one embodiment, a processor includes an execution unit and at least one last branch record (LBR) register to store address information of a branch taken during program execution. This register may further store a transaction indicator to indicate whether the branch was taken during a transactional memory (TM) transaction. This register may further store an abort indicator to indicate whether the branch was caused by a transaction abort. Other embodiments are described and claimed.

Abstract: A system, processor and method are provided for digital signal processing. A processor may initiate processing a sequence of instructions followed by an interrupt. Each instruction may be processed in respective sequential pipeline slots. A branch detector may detect or determine if an instruction is a branch instruction, for example, in turn, for each sequential instruction. In one embodiment, the branch detector may detect if an instruction is a branch instruction until at least a first branch instruction is detected. A processor may annul instructions which are determined to be branch instructions when the interrupt occupies a delay slot associated with the branch instruction. An execution unit may execute at least the sequence of instructions to run a program. The branch detector and/or execution unit may be integral or separate from each other and from the processor.

Abstract: A method and circuit arrangement for selectively predicating an instruction in an instruction stream based upon a value corresponding to a predication register address indicated by a portion of an operand associated with the instruction. A first compare instruction in an instruction stream stores a compare result in at a register address of a predication register. The register address of the predication register is stored in a portion of an operand associated with a second instruction, and during decoding the second instruction, the predication register is accessed to determine a value stored at the register address of the predication register, and the second instruction is selectively predicated based on the value stored at the register address of the predication register.

Abstract: Mechanisms, in a data processing system having a processor, for generating enqueued data for performing computations of a conditional branch of code are provided. Mask generation logic of the processor operates to generate a mask representing a subset of iterations of a loop of the code that results in a condition of the conditional branch being satisfied. The mask is used to select data elements from an input data element vector register corresponding to the subset of iterations of the loop of the code that result in the condition of the conditional branch being satisfied. Furthermore, the selected data elements are used to perform computations of the conditional branch of code. Iterations of the loop of the code that do not result in the condition of the conditional branch being satisfied are not used as a basis for performing computations of the conditional branch of code.

Abstract: A processor and method for maintaining the integrity of an execution return address stack (RAS). The execution RAS is maintained in an accurate state by storing information regarding branch instructions in a branch information table. The first time a branch instruction is executed, an entry is allocated and populated in the table. If the branch instruction is re-executed, a pointer address is retrieved from the corresponding table entry and the execution RAS pointer is repositioned to the retrieved pointer address. The execution RAS can also be used to restore a speculative RAS due to a mis-speculation.

Abstract: One embodiment of the present invention sets forth a technique instruction level and compute thread array granularity execution preemption. Preempting at the instruction level does not require any draining of the processing pipeline. No new instructions are issued and the context state is unloaded from the processing pipeline. When preemption is performed at a compute thread array boundary, the amount of context state to be stored is reduced because execution units within the processing pipeline complete execution of in-flight instructions and become idle. If, the amount of time needed to complete execution of the in-flight instructions exceeds a threshold, then the preemption may dynamically change to be performed at the instruction level instead of at compute thread array granularity.

Abstract: A method includes executing a branch instruction and determining if a branch is taken. The method further includes evaluating a number of instructions associated with the branch instruction. Upon determining that the branch is taken, the method includes selectively writing an entry into a branch target buffer that corresponds to the taken branch responsive to determining that the number of instructions is less than a threshold.

Abstract: Embodiments of a system and method are disclosed that can include a memory unit, and a memory management unit coupled to the memory unit. The memory management unit can include address mapping circuitry and access control circuitry operable to: provide address mappings for at least a frame stack and a link stack in the memory unit for programs being executed by the processing unit, and provide an access permission indicator applicable to any segment of the memory unit. A processing unit can save context information for a program to the frame stack, and execute a savelink instruction subsequent to the execution of a branch and link instruction. If the access permission indicator is set, the savelink instruction saves to the link stack a return address provided by the branch and link instruction.

Abstract: Data operand fetching control includes calculating a summation weight value for each instruction in a pipeline, the summation weight value calculated as a function of branch uncertainty and a pendency in which the instruction resides in the pipeline relative to other instructions in the pipeline. The data operand fetching control also includes mapping the summation weight value of a selected instruction that is attempting to access system memory to a memory access control. Each memory access control specifies a manner of handling data fetching operations. The data operand fetching control further includes performing a memory access operation for the selected instruction based upon the mapping.

Abstract: Techniques are disclosed for generating fast vector masking SIMD code corresponding to source code having a conditional statement, where the SIMD code replaces the conditional statements with vector SIMD operations. One technique includes performing conditional masking using vector operations, bit masking operations, and bitwise logical operations. The need for conditional statements in SIMD code is thereby removed, allowing SIMD hardware to avoid having to use branch prediction. This reduces the number of pipeline stalls and results in increased utilization of the SIMD computational units.

Abstract: This disclosure describes techniques for handling divergent thread conditions in a multi-threaded processing system. In some examples, a control flow unit may obtain a control flow instruction identified by a program counter value stored in a program counter register. The control flow instruction may include a target value indicative of a target program counter value for the control flow instruction. The control flow unit may select one of the target program counter value and a minimum resume counter value as a value to load into the program counter register. The minimum resume counter value may be indicative of a smallest resume counter value from a set of one or more resume counter values associated with one or more inactive threads. Each of the one or more resume counter values may be indicative of a program counter value at which a respective inactive thread should be activated.

Abstract: The computer system of the present invention emulates target instructions. The computer system includes a processing unit for branching to collective emulation coding for emulating plural of target instructions created beforehand collectively, thereby processing those instructions collectively according to the coding when those target instructions are combined so as to be processed collectively and a memory for storing the collective emulation coding.

Abstract: A method for a hybrid code signature including executing, via a processor, an application, the executing comprising executing a root instruction of the application; profiling, via the processor, the executing of the application, the profiling comprising storing a reference signature; determining, via the processor, a working signature of instructions executed subsequent to the executing of the root instruction, the determining comprising implementing a hashing function of the instructions in response to storing the reference signature; tracking the updating of the working signature by storing a value in a counter; and updating continuously, via the processor, the working signature with the hashing function while at least the working signature does not match the reference signature.

Abstract: A method of performing operations in a computer system, computer system, and related method of compilation, are disclosed. In one embodiment, the method of performing includes providing compiled code having at least one thread, where each of the at least one thread includes a respective plurality of blocks and each respective block includes a respective pre-fetch component and a respective execute component. The method also includes performing a first pre-fetch component from a first block of a first thread of the at least one thread, performing a first additional component after the first pre-fetch component has been performed, and performing a first execute component from the first block of the first thread. The first execute component is performed after the first additional component has been performed, and the first additional component is from either a second thread or another block of the first thread that is not the first block.

Abstract: Some embodiments of the present invention provide a system that tests a software program. During operation, the system traces a flow of tainted data through the software program during execution of the software program. Next, the system alters the flow by modifying an instruction within the software program. The system then monitors the behavior of the software program after modifying the instruction. Finally, the system analyzes a correctness of the software program based on the monitored behavior.

Abstract: A data processor includes a branch target buffer (BTB) having a plurality of BTB entries grouped in ways. The BTB entries in one of the ways include a short tag address and the BTB entries in another one of the ways include a full tag address.

Abstract: Methods and systems consistent with the present invention provide a programmable table which allows software to define a plurality of branching functions, each of which maps a vector of condition codes to a branch offset. This technique allows for a flexible multi-way branching functionality, using a conditional branch outcome table that can be specified by a programmer. Any instruction can specify the evaluation of arbitrary conditional expressions to compute the values for the condition codes, and can choose a particular branching function. When the processor executes the instruction, the processor's arithmetic/logical functional units evaluate the conditional expressions and then the processor performs the branch operation, according to the specified branching function.

Abstract: In one embodiment, a processor includes a performance monitor including a last branch record (LBR) stack to store a call stack to an event of interest, where the call stack is collected responsive to a trigger for the event. The processor further includes logic to control the LBR stack to operate in a call stack mode such that an entry to a call instruction for a leaf function is cleared on return from the leaf function. Other embodiments are described and claimed.

Abstract: A processor configured to facilitate transfer and storage of predicted targets for control transfer instructions (CTIs). In certain embodiments, the processor may be multithreaded and support storage of predicted targets for multiple threads. In some embodiments, a CTI branch target may be stored by one element of a processor and a tag may indicate the location of the stored target. The tag may be associated with the CTI rather than associating the complete target address with the CTI. When the CTI reaches an execution stage of the processor, the tag may be used to retrieve the predicted target address. In some embodiments using a tag to retrieve a predicted target, CTI instructions from different processor threads may be interleaved without affecting retrieval of predicted targets.

Abstract: An indirect branch instruction takes an address register as an argument in order to provide indirect function call capability for single-instruction multiple-thread (SIMT) processor architectures. The indirect branch instruction is used to implement indirect function calls, virtual function calls, and switch statements to improve processing performance compared with using sequential chains of tests and branches.

Abstract: A method and apparatus for optimizing a target program including a pattern of instructions to be replaced. The method is performed by execution of program code by a processor of an information processing apparatus that includes an output device and a computer readable storage medium storing the program code. At least one transformation is performed on the target program to generate a transformed target subprogram in which dependencies among the instructions included in the target subprogram are matched with dependencies in the pattern to be replaced. The transformed target subprogram is replaced, with a post-replacement instruction stream determined to correspond to the pattern to be replaced, to generate a replaced target subprogram. An optimized target program that includes the replaced target subprogram is outputted to the output device. The at least one transformation includes a first transformation, a loop transformation, or both the first transformation and the loop transformation.

Abstract: A branch predicting apparatus is disclosed that reduces branch mispredictions in a processor. The branch prediction apparatus includes a base misprediction history register. The branch prediction apparatus includes a meta predictor that receives an index value and a branch prediction to generate a misprediction value in accordance with the base misprediction history register. The branch prediction apparatus also includes a logic gate that receives the branch prediction and the misprediction value to generate a final prediction. The final prediction may be used to predict whether a branch is taken or not taken.

Abstract: In one embodiment the present invention includes a microprocessor that has a pipeline circuit, a branch circuit, and a control circuit. The pipeline circuit pipelines instructions for the microprocessor. The branch circuit is coupled to the pipeline circuit and operates to store branch information. The control circuit is coupled to the pipeline circuit and the branch circuit. The control circuit stores a first branch information from the pipeline circuit to the branch circuit when a first condition is met. The control circuit retrieves a second branch information from the branch stack circuit to the pipeline circuit when a second condition is met. In this manner, the need for dedicated pipeline flush circuitry is avoided.

Abstract: Mechanisms are provided for dynamically rewriting branch instructions in a portion of code. The mechanisms execute a branch instruction in the portion of code. The mechanisms determine if a target instruction of the branch instruction, to which the branch instruction branches, is present in an instruction cache associated with the processor. Moreover, the mechanisms directly branch execution of the portion of code to the target instruction in the instruction cache, without intervention from an instruction cache runtime system, in response to a determination that the target instruction is present in the instruction cache. In addition, the mechanisms redirect execution of the portion of code to the instruction cache runtime system in response to a determination that the target instruction cannot be determined to be present in the instruction cache.

Abstract: An obfuscation device includes a first instruction generating unit, for each of a first process and a second process, which generates an initialization instruction for securing a management area for managing identification information indicating an instruction block that should be executed next so as to proceed with the process. Further, a second instruction generating unit generates a selection instruction (i) to make a first selection selecting a process that should be proceeded out of the first process and the second process, (ii) to make a second selection selecting an instruction block indicated by the identification information managed in the management area as an instruction block that should be executed for proceeding with the process selected by the first selection, and (iii) to cause the execution device to execute the instruction block selected by the second selection, and stores the selection instruction in a storage unit.

Abstract: A method may include distributing ranges of addresses in a memory among a first set of functions in a first pipeline. The first set of the functions in the first pipeline may operate on data using the ranges of addresses. Different ranges of addresses in the memory may be redistributed among a second set of functions in a second pipeline without waiting for the first set of functions to be flushed of data.

Abstract: An embodiment of an instruction pipeline includes first and second sections. The first section is operable to provide first and second ordered instructions, and the second section is operable, in response to the second instruction, to read first data from a data-storage location, is operable, in response to the first instruction, to write second data to the data-storage location after reading the first data, and is operable, in response to the writing the second data after reading the first data, to cause the flushing of a some, but not all, of the pipeline. Such an instruction pipeline may reduce the processing time lost and the energy expended due to a pipeline flush by flushing only a portion of the pipeline instead of flushing the entire pipeline.

Abstract: Hardware and software techniques for interrupt detection and response in a scalable pipelined array processor environment are described. Utilizing these techniques, a sequential program execution model with interrupts can be maintained in a highly parallel scalable pipelined array processing containing multiple processing elements and distributed memories and register files. When an interrupt occurs, interface signals are provided to all PEs to support independent interrupt operations in each PE dependent upon the local PE instruction sequence prior to the interrupt. Processing/element exception interrupts are supported and low latency interrupt processing is also provided for embedded systems where real time signal processing is to required. Further, a hierarchical interrupt structure is used allowing a generalized debug approach using debut interrupts and a dynamic debut monitor mechanism.

Abstract: A method of processing data is disclosed that includes performing a fetch of a plurality of instructions from a memory unit. The method also includes grouping the plurality of instructions into packets of instructions of different types for parallel execution by a plurality of instruction execution units. The packets of instructions include a first instruction and a second instruction. The method includes using a combined scalar and vector condition code register to execute the first instruction for a compare operation and the second instruction for a conditional operation using the combined scalar and vector condition code register. The method also includes when the compare operation is a scalar compare operation, receiving a scalar compare instruction for the scalar compare operation at an instruction executing unit and storing results of the scalar compare operation in the combined scalar and vector condition code register.

Abstract: Processors may be tested according to various implementations. In one general implementation, a process for processor testing may include randomly generating a first plurality of branch instructions for a first portion of an instruction set, each branch instruction in the first portion branching to a respective instruction in a second portion of the instruction set, the branching of the branch instructions to the respective instructions being arranged in a sequential manner. The process may also include randomly generating a second plurality of branch instructions for the second portion of the instruction set, each branch instruction in the second portion branching to a respective instruction in the first portion of the instruction set, the branching of the branch instructions to the respective instructions being arranged in a sequential manner. The process may additionally include generating a plurality of instructions to increment a counter when each branch instruction is encountered during execution.

Abstract: Hardware and software techniques for interrupt detection and response in a scalable pipelined array processor environment are described. Utilizing these techniques, a sequential program execution model with interrupts can be maintained in a highly parallel scalable pipelined array processing containing multiple processing elements and distributed memories and register files. When an interrupt occurs, interface signals are provided to all PEs to support independent interrupt operations in each PE dependent upon the local PE instruction sequence prior to the interrupt. Processing/element exception interrupts are supported and low latency interrupt processing is also provided for embedded systems where real time signal processing is required. Further, a hierarchical interrupt structure is used allowing a generalized debug approach using debut interrupts and a dynamic debut monitor mechanism.

Abstract: When selecting one command within a processor from a plurality of command queues vested with order of priority, the order of priority assigned to the plurality of command queues is dynamically changed so as to select a command, on a priority basis, from a command queue vested with a higher priority from among the plurality of command queues in accordance with the post-change order of priority.

Abstract: When two threads (strands), for example, are executed in parallel in a processor in a simultaneous multi-thread (SMT) system, entries of a branch reservation station of an instruction control device are separately used in a strand 0 group and a strand 1 group. The data of the strand 0 and the data of the strand 1 are allocated to the respective entries by switching a select circuit. When an entry is released from the branch reservation station, the select circuit switches the strands so that a branch instruction in one strand can be released in order, thereby releasing the entry.

Abstract: A systolic data processing apparatus includes a processing element (PE) array and control unit. The PE array comprises a plurality of PEs, each PE executing a thread with respect to different data according to an input instruction and pipelining the instruction at each cycle for executing a program. The control unit inputs a new instruction to a first PE of the PE array at each cycle.

Abstract: A data processor or a data processing system used in compatible modes among which the number of bits of an address specifying a logical address space varies at the time of referring to a branch address table by extension of displacement of a branch instruction. At the time of generating a branch address of a first branch instruction, the data processor or the data processing system optimizes a multiple with which a displacement is multiplied in accordance with the number of bits of an address specifying a logical address space, adds extended address information to the value of a register, and refers to a branch address table with address information obtained by the addition. The referred information is used as a branch address. A multiple with which the displacement is multiplied can be changed in accordance with the mode.

Abstract: A microprocessor includes a memory that stores instructions of a non-user program to implement a user program instruction of the user-visible instruction set of the microprocessor. The non-user program includes a conditional branch instruction. A first fetch unit fetches instructions of the user program that includes the instruction that is implemented by the non-user program. An instruction decoder decodes the user program instructions and saves a state in response to decoding the user program instruction that is implemented by the non-user program. An execution unit executes the user program instructions fetched by the first fetch unit and executes instructions of the non-user program other than the conditional branch instruction. A second fetch unit fetches the non-user program instructions from the memory and resolves the conditional branch instruction based on the saved state without sending the conditional branch instruction to the execution unit to resolve the conditional branch instruction.

Abstract: A processor includes an initiating hardware thread, which initiates a first assist hardware thread to execute a first code segment. Next, the initiating hardware thread sets an assist thread executing indicator in response to initiating the first assist hardware thread. The set assist thread executing indicator indicates whether assist hardware threads are executing. A second assist hardware thread initiates and begins executing a second code segment. In turn, the initiating hardware thread detects a change in the assist thread executing indicator, which signifies that both the first assist hardware thread and the second assist hardware thread terminated. As such, the initiating hardware thread evaluates assist hardware thread results in response to both of the assist hardware threads terminating.

Abstract: A microprocessor includes a control register that stores a control value that affects operation of the microprocessor. An instruction set architecture includes a conditional branch instruction that specifies a branch condition based on the control value stored in the control register, and a serializing instruction that updates the control value in the control register. The microprocessor completes all modifications to flags, registers, and memory by instructions previous to the serializing instruction and to drain all buffered writes to memory before it fetches and executes the next instruction after the serializing instruction. Execution units update the control value in the control register in response to the serializing instruction. A fetch unit fetches, decodes, and unconditionally correctly resolves and retires the conditional branch instruction based on the control value stored in the control register rather than dispatching the conditional branch instruction to the execution units to be resolved.