Abstract: Techniques are disclosed for performing issue queue snooping for an asynchronous flush and restore of a history buffer (HB) in a processing unit. One technique includes identifying an entry of the HB to restore to a register file in the processing unit. A restore ITAG of the HB entry is sent to the register file via a first restore bus, and restore data of the HB entry and the restore ITAG is sent to the register file via a second restore bus. After the restore ITAG and restore data are sent, an instruction is dispatched before the register file obtains the restore data. After it is determined that the restore data is still available via the second restore bus, a snooping operation is performed to obtain the restore data from the second restore bus for the dispatched instruction.

Abstract: A method and system of verifying proper execution of a secure mode entry sequence. At least some of the exemplary embodiments may be a method comprising delivering an instruction from a memory to a processor across an instruction bus (the instruction at least partially configures the processor for secure mode of operation different that privilege modes of the processor), verifying delivery of the instruction across the instruction bus, and checking for proper execution of the instruction using a trace port of the processor.

Abstract: Examples include a computing system having an input/output (I/O) device including a plurality of counters, each counter operating as one of a completion counter and a trigger counter, a processing device; and a memory device. The memory device stores instructions that, in response to execution by the processing device, cause the processing device to represent a plurality of triggered operations of collective communication for high-performance computing executable by the I/O device as a directed acyclic graph stored in the memory device, with triggered operations represented as vertices of the directed acyclic graph and dependencies between triggered operations represented as edges of the directed acyclic graph; traverse the directed acyclic graph using a first process to identify and mark vertices that can share a completion counter; and traverse the directed acyclic graph using a second process to assign a completion counter and a trigger counter for each vertex.

Abstract: A branch predictor is provided with a branch state buffer, branch prediction save circuitry responsive to a branch prediction save event associated with a given execution context to save at least a portion of the active branch prediction state associated with the given execution context to a branch state buffer; and branch prediction restore circuitry responsive to a branch prediction restore event associated with the given execution context to restore active branch prediction state based on previously saved branch prediction state stored in the branch state buffer for the given execution context. This is useful for reducing the performance impact of mitigating against speculative side-channel attacks.

Abstract: An apparatus and method are provided for performing branch prediction. The apparatus has processing circuitry for executing instructions, and branch prediction circuitry for making branch outcome predictions in respect of branch instructions. The branch prediction circuitry includes loop prediction circuitry having a plurality of entries, where each entry is used to maintain branch outcome prediction information for a loop controlling branch instruction that controls repeated execution of a loop comprising a number of instructions. The branch prediction circuitry is arranged to analyse blocks of instructions and to produce a prediction result for each block that is dependent on branch outcome predictions made for any branch instructions appearing in the associated block. A prediction queue then stores the prediction results produced by the branch prediction circuitry in order to determine the instructions to be executed by the processing circuitry.

Abstract: A data processing apparatus comprises branch prediction circuitry adapted to store at least one branch prediction state entry in relation to a stream of instructions, input circuitry to receive at least one input to generate a new branch prediction state entry, wherein the at least one input comprises a plurality of bits; and coding circuitry adapted to perform an encoding operation to encode at least some of the plurality of bits based on a value associated with a current execution environment in which the stream of instructions is being executed. This guards against potential attacks which exploit the ability for branch prediction entries trained by one execution environment to be used by another execution environment as a basis for branch predictions.

Abstract: An apparatus comprises a branch target buffer (BTB) to store predicted target addresses of branch instructions. In response to a fetch block address identifying a fetch block comprising two or more program instructions, the BTB performs a lookup to identify whether it stores one or more predicted target addresses for one or more branch instructions in the fetch block. When the BTB is identified in the lookup as storing predicted target addresses for more than one branch instruction in said fetch block, branch target selecting circuitry selects a next fetch block address from among the multiple predicted target addresses returned in the lookup. A shortcut path bypassing the branch target selecting circuitry is provided to forward a predicted target address identified in the lookup as the next fetch block address when a predetermined condition is satisfied.

Abstract: Table of Contents (TOC)-setting instructions are replaced in code with TOC predicting instructions. A determination is made as to whether code includes an instruction sequence to compute a value of a pointer to a reference data structure, such as a TOC. Based on determining the code includes the instruction sequence, the instruction sequence in the code is replaced with a set instruction. The set instruction predicts the value of the pointer to the reference data structure.

Abstract: Operation of a multi-slice processor implementing a tagged geometric history length prediction unit and an effective address table aligned with an update table, where the multi-slice processor includes a plurality of execution slices. Operation of such a multi-slice processor includes: receiving, at an effective address table and at a TAGE update table, information for a branch instruction dispatched to an execution slice, wherein the effective address table and the TAGE update table are in alignment; responsive to the branch instruction being taken, updating the effective address table and the TAGE update table to indicate the branch instruction being taken; and updating, in dependence upon the alignment between the effective address table and the TAGE update table, the TAGE branch prediction unit with update information from both the effective address table and the TAGE update table.

Abstract: Methods and apparatuses relating to dynamic asymmetric scaling of branch predictor tables are described. Branch predictor circuits to perform dynamic asymmetric scaling of branch predictor tables are also described.

Abstract: An apparatus and method are provided for controlling branch prediction. The apparatus has processing circuitry for executing instructions, and branch prediction circuitry that comprises a plurality of branch prediction mechanisms used to predict target addresses for branch instructions to be executed by the processing circuitry. The branch instructions comprise a plurality of branch types, where one branch type is a return instruction. The branch prediction mechanisms include a return prediction mechanism used by default to predict a target address when a return instruction is detected by the branch prediction circuitry. However, the branch prediction circuitry is responsive to a trigger condition indicative of misprediction of the target address when using the return prediction mechanism to predict the target address for a given return instruction, to switch to using an alternative branch prediction mechanism for predicting the target address for the given return instruction.

Abstract: In various embodiments, a branch prediction redirection system may include a first branch prediction circuit configured to predict a first target of a branch instruction and a second branch prediction circuit configured to predict a second target of the branch instruction. A redirection circuit may send a pipeline redirection indication in response to the first target differing from the second target. A suppression circuit may prevent the pipeline redirection indication from being sent in response to identifying that data corresponding to the branch instruction indicates a potential multi-hit.

Abstract: A predicted branch result is determined based on at least a portion of branch prediction information, which is updated based on an actual branch result, which is provided based on an executed branch instruction. For a first execution of a first branch instruction, the updating includes: computing a randomized value and storing the randomized value in association with an identified subset of one or more contexts that includes a context associated with the first branch instruction, obfuscating the actual branch result based at least in part on the randomized value, and storing a resulting obfuscated value in the branch prediction information. Providing a predicted branch result for a second execution of the first branch instruction includes: retrieving the obfuscated value from the branch prediction information, retrieving the randomized value, and de-obfuscating the obfuscated value using the randomized value to recover the actual branch result as the predicted branch result.

Abstract: Embodiments of apparatuses, methods, and systems for misprediction-triggered local history-based branch prediction are described. In one embodiments, an apparatus includes a current pattern table and a local pattern table. The current pattern table has a plurality of entries, each entry in which to store a plurality of pattern lengths of a current pattern of one of a plurality of branch instructions. The local pattern table is to provide a first branch prediction based on the current pattern.

Abstract: Instructions are executed in a pipeline of a processor, where each instruction is associated with a particular context. A first storage stores branch prediction information characterizing results of branch instructions previously executed. The first storage is dynamically partitioned into partitions of one or more entries. Dynamically partitioning includes updating a partition to include an additional entry by associating the additional entry with a particular subset of one or more contexts. A predicted branch result is determined based on at least a portion of the branch prediction information. An actual branch result provided based on an executed branch instruction is used to update the branch prediction information. Providing a predicted branch result for a first branch instruction includes retrieving a first entry from a first partition based at least in part on an identified first subset of one or more contexts associated with the first branch instruction.

Abstract: Branch instructions are managed in an emulation environment that is executing a program. A plurality of slots in a Polymorphic Inline Cache is populated. A plurality of entries is populated in a branch target buffer residing within an emulated environment in which the program is executing. When an indirect branch instruction associated with the program is encountered, a target address associated with the instruction is identified from the indirect branch instruction. At least one address in each of the slots of the Polymorphic Inline Cache is compared to the target address associated with the indirect branch instruction. If none of the addresses in the slots of the Polymorphic Inline Cache matches the target address associated with the indirect branch instruction, the branch target buffer is searched to identify one of the entries in the branch target buffer that is associated with the target address of the indirect branch instruction.

Abstract: Technologies for control flow validation a computing device having a processor with real-time instruction tracing support. The processor generates trace data indicative of control flow of a protected application. The computing device identifies an indirect branch target based on the trace data and determines whether the indirect branch target is included in the same module as a previous indirect branch target. If the indirect branch target and the previous indirect branch target are not included in the same module, the computing device determines whether an inter-module transfer policy is satisfied. If satisfied, the indirect branch target is stored as the previous indirect branch target and the protected application continues to execute. If the policy is not satisfied, the computing device generates an exception. The policy may be satisfied, for example, if the indirect branch target is an exported function. Other embodiments are described and claimed.

Abstract: Methods and apparatus for preventing premature reads from a general purpose register (GPR) including receiving an instruction comprising a source operand identifying a source GPR entry; setting a read-enabled flag based on a value in a particular entry of a source ready vector; if the read-enabled flag indicates data in the source GPR entry is ready for reading, dispatching the received instruction, including performing a read operation of the data in the source GPR entry; and if the read-enabled flag indicates data in the source GPR entry is not ready for reading, dispatching the received instruction without performing a read operation of the data in the source GPR entry.

Abstract: Aspects of the present invention provide a memory system comprising a plurality of stacked memory layers, each memory layer divided into memory sections, wherein each memory section connects to a neighboring memory section in an adjacent memory layer, and a logic layer stacked among the plurality of memory layers, the logic layer divided into logic sections, each logic section including a memory processing core, wherein each logic section connects to a neighboring memory section in an adjacent memory layer to form a memory vault of connected logic and memory sections, and wherein each logic section is configured to communicate directly or indirectly with a host processor. Accordingly, each memory processing core may be configured to respond to a procedure call from the host processor by processing data stored in its respective memory vault and providing a result to the host processor. As a result, increased performance may be provided.

Abstract: Methods and indirect branch predictor logic units to predict the target addresses of indirect branch instructions. The method comprises storing in a table predicted target addresses for indirect branch instructions indexed by a combination of the indirect path history for previous indirect branch instructions and the taken/not-taken history for previous conditional branch instructions. When a new indirect branch instruction is received for prediction, the indirect path history and the taken/not-taken history are combined to generate an index for the indirect branch instruction. The generated index is then used to identify a predicted target address in the table. If the identified predicted target address is valid, then the target address of the indirect branch instruction is predicted to be the predicted target address.

Abstract: At a cache manager of a directed acyclic graph-based data analytic platform, memory usage statistics are obtained from each of a plurality of monitor components on a plurality of worker nodes. The worker nodes have a plurality of tasks executing thereon, and each of the tasks has at least one distributed dataset associated therewith. Each of the worker nodes has a distributed dataset cache. At least one of the following is carried out: increasing a size of a given one of the distributed dataset caches if the memory usage statistics indicate that corresponding ones of the tasks are using too little memory; and decreasing a size of another given one of the distributed dataset caches if the memory usage statistics indicate contention between corresponding ones of the tasks and a corresponding one of the distributed datasets.

Abstract: A method and system for storing branch information is disclosed. First data may be stored in a first entry of a first table in response to a determination that a fetched instruction is a branch instruction. Second data that is dependent upon at least one previously taken branch may be stored in a second entry in a second table in response to a determination that a branch associated with the instruction is predicted to be taken. The first data may be updated to include an index to the second data in response to the determination that the branch is predicted to be taken.

Abstract: The disclosure provides a micro-processing system operable in a hardware decoder mode and in a translation mode. In the hardware decoder mode, the hardware decoder receives and decodes non-native ISA instructions into native instructions for execution in a processing pipeline. In the translation mode, native translations of non-native ISA instructions are executed in the processing pipeline without using the hardware decoder. The system includes a code portion profile stored in hardware that changes dynamically in response to use of the hardware decoder to execute portions of non-native ISA code. The code portion profile is then used to dynamically form new native translations executable in the translation mode.

Abstract: This disclosure includes a method for performing branch prediction by a processor having an instruction pipeline. The processor speculatively updates a global history register having fetch group history and branch history, fetches a fetch group of instructions, and assigns a global history vector to the instructions. The processor predicts any branches in the fetch group using the global history vector and a predictor, and evaluates whether the fetch group contains a predicted taken branch. If the fetch group contains a predicted taken branch, the processor flushes subsequently fetched instructions in the pipeline following the predicted taken branch, repairs the global history register to the global history vector, and updates the global history register based on branch prediction information. If the fetch group does not contain a predicted taken branch, the processor updates the global history register with a branch history value for each branch in the fetch group.

Abstract: Branch prediction is provided by generating a first index from a previous instruction address and from a first branch history vector having a first length. A second index is generated from the previous instruction address and from a second branch history vector that is longer than the first vector. Using the first index, a first branch prediction is retrieved from a first branch prediction table. Using the second index, a second branch prediction is retrieved from a second branch prediction table. Based upon additional branch history data, the first branch history vector and the second branch history vector are updated. A first hash value is generated from a current instruction address and the updated first branch history vector. A second hash value is generated from the current instruction address and the updated second branch history vector. One of the branch predictions are selected based upon the hash values.

Abstract: Branch prediction is provided by generating a first index from a previous instruction address and from a first branch history vector having a first length. A second index is generated from the previous instruction address and from a second branch history vector that is longer than the first vector. Using the first index, a first branch prediction is retrieved from a first branch prediction table. Using the second index, a second branch prediction is retrieved from a second branch prediction table. Based upon additional branch history data, the first branch history vector and the second branch history vector are updated. A first hash value is generated from a current instruction address and the updated first branch history vector. A second hash value is generated from the current instruction address and the updated second branch history vector. One of the branch predictions are selected based upon the hash values.

Abstract: Embodiments relate to selectively blocking branch instruction predictions. An aspect includes computer implemented method for performing selective branch prediction. The method includes detecting, by a processor, a branch-prediction blocking instruction in a stream of instructions and blocking, by the processor, branch prediction of a predetermined number of branch instructions following the branch-prediction blocking instruction based on the detecting the branch-prediction blocking instruction.

Abstract: A method, a non-transitory computer readable medium, and a processor for repacking dynamic wavefronts during program code execution on a processing unit, each dynamic wavefront including multiple threads are presented. If a branch instruction is detected, a determination is made whether all wavefronts following a same control path in the program code have reached a compaction point, which is the branch instruction. If no branch instruction is detected in executing the program code, a determination is made whether all wavefronts following the same control path have reached a reconvergence point, which is a beginning of a program code segment to be executed by both a taken branch and a not taken branch from a previous branch instruction. The dynamic wavefronts are repacked with all threads that follow the same control path, if all wavefronts following the same control path have reached the branch instruction or the reconvergence point.

Abstract: Embodiments relate to selectively blocking branch instruction predictions. An aspect includes a computer system for performing selective branch prediction. The system includes memory and a processor, and the system is configured to perform a method. The method includes detecting a branch-prediction blocking instruction in a stream of instructions and blocking branch prediction of a predetermined number of branch instructions following the branch-prediction blocking instruction based on the detecting the branch-prediction blocking instruction.

Abstract: A microprocessor includes a predicting unit having storage for holding a prediction history of characteristics of instructions previously executed by the microprocessor. The predicting unit accumulates the prediction history and uses the prediction history to make predictions related to subsequent instruction executions. The storage comprises a plurality of portions separately controllable for accumulating the prediction history. The microprocessor also includes a control unit that detects the microprocessor is running an operating system routine and controls the predicting unit to use only a fraction of the plurality of portions of the storage to accumulate the prediction history while the microprocessor is running the operating system routine.

Abstract: A loop predictor trains a branch instruction to determine a trained loop count of a loop. When the loop fits in an instruction buffer, the processor stops fetching from an instruction cache, sends the loop instructions to an execution engine from the buffer without fetching from the cache, maintains a loop pop count of times the branch is sent to the execution engine from the buffer, and predicts the branch instruction is taken when the loop pop count is less than the trained loop count and otherwise predicts not taken.

Abstract: This disclosure includes a method for performing branch prediction by a processor having an instruction pipeline. The processor speculatively updates a global history register having fetch group history and branch history, fetches a fetch group of instructions, and assigns a global history vector to the instructions. The processor predicts any branches in the fetch group using the global history vector and a predictor, and evaluates whether the fetch group contains a predicted taken branch. If the fetch group contains a predicted taken branch, the processor flushes subsequently fetched instructions in the pipeline following the predicted taken branch, repairs the global history register to the global history vector, and updates the global history register based on branch prediction information. If the fetch group does not contain a predicted taken branch, the processor updates the global history register with a branch history value for each branch in the fetch group.

Abstract: A split level history buffer in a central processing unit is provided. A first instruction and a second instruction are fetched, tagged, and the first instruction is stored an entry of a register file. The first instruction is evicted from the entry and the second instruction is stored in the entry. If the first instruction is evicted, then the first instruction is stored in a first portion of a history buffer. If a result for the first instruction is generated, then the first instruction is moved to a second portion of the history buffer and the result is stored with the first instruction in the second portion of the history buffer. If it is determined that a third instruction evicts the second instruction from the entry, then the second instruction is stored in the first portion of the history buffer.

Abstract: Methods and indirect branch predictor logic units to predict the target addresses of indirect branch instructions. The method comprises storing in a table predicted target addresses for indirect branch instructions indexed by a combination of the indirect path history for previous indirect branch instructions and the taken/not-taken history for previous conditional branch instructions. When a new indirect branch instruction is received for prediction, the indirect path history and the taken/not-taken history are combined to generate an index for the indirect branch instruction. The generated index is then used to identify a predicted target address in the table. If the identified predicted target address is valid, then the target address of the indirect branch instruction is predicted to be the predicted target address.

Abstract: A branch history table cache is a write cache that stores values of branch history counters written to a branch history table. An update to a branch history table counter is reflected in both the branch history table cache and the branch history table. Before a branch history table counter is updated, a check is made to see if the branch history table counter is in the cache. If not, the branch history table counter is updated based on a value of the branch history table counter that was saved during fetch of the branch history table counter. If, however, the branch history table counter value is in the cache, the value in the cache is used to update the branch history table counter. All branches that use the branch history table counter update the correct counter value, improving processor performance by providing more accurate predictions of branches taken.

Abstract: A processor system tracks, in at least one counter, a number of cycles in which at least one execution unit of at least one processor core is idle and at least one thread of the at least one processor core is waiting on at least one off-core memory access during run-time of the at least one processor core during an interval comprising multiple cycles. The processor system evaluates an expected performance impact of a frequency change within the at least one processor core based on the current run-time conditions for executing at least one operation tracked in the at least one counter during the interval.

Abstract: Techniques relate to dynamic branch history pattern adjustment. Past histories of branch instruction results are collected as part of a branch history pattern. A branch prediction structure with a pattern history buffer predicts a direction of a branch instruction using the branch history pattern. The branch prediction structure executes one or more branch history pattern recording adjustment instructions prior to one or more branch instructions. Executing the one or more branch history pattern recording adjustment instructions changes default behaviors of recording and usage of the branch history pattern.

Abstract: An arithmetic processing device includes: first prediction units which output branch prediction information of a fetched conditional branch instruction based on past branch history information of conditional branch instructions; a second prediction unit which stores a branch taken consecutive number of times and a branch not-taken consecutive number of times to a pattern information storage unit, and outputs branch prediction information of a fetched conditional branch instruction based on the past branch taken consecutive number of times or branch not-taken consecutive number of times stored; selecting units which selectively output the branch prediction information output from the first prediction units or the second prediction unit; and a selector which outputs a next instruction address of the conditional branch instruction or a branch target address of the conditional branch instruction to an instruction fetch unit in accordance with the branch prediction information output by the selecting units.

Abstract: A predictor data structure is used for pipelined processing by a pipelined processor. The predictor data structure includes a predicted address to be used in return from execution of a selected instruction, and a predicted operating state associated with the predicted address. Based on determining a selected return instruction is to be executed, the predicted address to which processing is to be returned is obtained from the predictor data structure. Further, based on determining the selected return instruction is to be executed, a transitional operating state to be entered based on the predicted operating state stored in the predictor data structure is predicted, wherein at least one of the predicted address and the predicted transitional operating state are to be used to validate execution of the selected return instruction.

Abstract: A predictor data structure is used for pipelined processing by a pipelined processor. The predictor data structure includes a predicted address to be used in return from execution of a selected instruction, and a predicted operating state associated with the predicted address. Based on determining a selected return instruction is to be executed, the predicted address to which processing is to be returned is obtained from the predictor data structure. Further, based on determining the selected return instruction is to be executed, a transitional operating state to be entered based on the predicted operating state stored in the predictor data structure is predicted, wherein at least one of the predicted address and the predicted transitional operating state are to be used to validate execution of the selected return instruction.

Abstract: A microprocessor includes a predicting unit and a control unit. The control unit controls the predicting unit to accumulate a history of characteristics of executed instructions and makes predictions related to subsequent instructions based on the history while the microprocessor is running a first thread. The control unit also detects a transition from running the first thread to running a second thread and controls the predicting unit to selectively suspend accumulating the history and making the predictions using the history while running the second thread. The predicting unit makes static predictions while running the second thread. The selectivity may be based on the privilege level, identity or length of the second thread, static prediction effectiveness during a previous execution instance of the thread, whether the transition was made due to a system call, and whether the second thread is an interrupt handler.

Abstract: Branch prediction is provided by generating a first index from a previous instruction address and from a first branch history vector having a first length. A second index is generated from the previous instruction address and from a second branch history vector that is longer than the first vector. Using the first index, a first branch prediction is retrieved from a first branch prediction table. Using the second index, a second branch prediction is retrieved from a second branch prediction table. Based upon additional branch history data, the first branch history vector and the second branch history vector are updated. A first hash value is generated from a current instruction address and the updated first branch history vector. A second hash value is generated from the current instruction address and the updated second branch history vector. One of the branch predictions are selected based upon the hash values.

Abstract: A branch prediction unit BPU (500) for prediction of a next taken branch instruction in a processing unit (100). The BPU (500) comprises a pattern history memory (504) comprising branch source addresses and branch indicators; a branch target buffer (506) comprising branch targets; and branch prediction logical circuit (502). By means of a search PC, the circuit finds in the memory a branch indicator indicating a predicted taken branch instruction. The circuit selects a first found branch indicator as an indication of a first predicted taken branch instruction. Using the first found branch indicator, the circuit retrieves from the memory, a branch source address of the first predicted taken branch instruction. When the retrieved branch source address is the branch source address nearest to the search PC, the circuit outputs as next PC a branch target retrieved from the buffer. Then the prediction stops.

Abstract: In accordance with some embodiments of the present invention, a branch prediction unit for an embedded controller may be placed in association with the instruction fetch unit instead of the decode stage. In addition, the branch prediction unit may include no branch predictor. Also, the return address stack may be associated with the instruction decode stage and is structurally separate from the branch prediction unit. In some cases, this arrangement reduces the area of the branch prediction unit, as well as power consumption.

Abstract: A method of predicting a backward conditional branch instruction used in a vector partitioning loop includes detecting the first conditional branch instruction that occurs after consumption of a dependency index vector by a predicate generating instruction. The dependency index vector includes information indicative of a number of iterations of the vector partitioning loop, and the conditional branch instruction may branch backwards when taken. The conditional branch instruction may then be predicted to be taken a number of times that is determined by the dependency index vector.

Abstract: A machine readable storage medium containing program code is described that when processed by a processor causes a method to be performed. The method includes creating a resultant rolled version of an input vector by forming a first intermediate vector, forming a second intermediate vector and forming a resultant rolled version of an input vector. The first intermediate vector is formed by barrel rolling elements of the input vector along a first of two lanes defined by an upper half and a lower half of the input vector. The second intermediate vector is formed by barrel rolling elements of the input vector along a second of the two lanes. The resultant rolled version of the input vector is formed by incorporating upper portions of one of the intermediate vector's upper and lower halves as upper portions of the resultant's upper and lower halves and incorporating lower portions of the other intermediate vector's upper and lower halves as lower portions of the resultant's upper and lower halves.

Abstract: A processor is operable to process conditional branches. The processor includes instruction fetch logic to fetch a conditional short forward branch. The conditional short forward branch is to include a conditional branch instruction and a set of one or more instructions that are to sequentially follow the conditional branch instruction in program order. The set of the one or more instructions are between the conditional branch instruction and a forward branch target instruction that is to be indicated by the conditional branch instruction. The processor also includes instruction conversion logic coupled with the instruction fetch logic. The instruction conversion logic is to convert the conditional short forward branch to a computationally equivalent set of one or more predicated instructions. Other processors are also disclosed, as are various methods and systems.

Abstract: A processing device implementing an elapsed cycle timer in last branch records (LBRs) is disclosed. A processing device of the disclosure includes a last branch record (LBR) counter to iterate with each cycle of the processing device and an LBR structure communicably coupled to the LBR counter. The LBR structure comprises a plurality of LBR entries. Furthermore, an LBR entry of the plurality of LBR entries comprises an address instruction pointer (IP) of a branch instruction executed by the processing device, an address IP of a target of the branch instruction, and an elapsed time field that stores a value of the LBR counter when the LBR entry is created.

Abstract: A microprocessor processes conditional non-branch instructions that specify a condition and instruct the microprocessor to perform an operation if the condition is satisfied and otherwise to not perform the operation. A predictor provides a prediction about a conditional non-branch instruction. An instruction translator translates the conditional non-branch instruction into a no-operation microinstruction when the prediction predicts the condition will not be satisfied, and into a set of one or more microinstructions to unconditionally perform the operation when the prediction predicts the condition will be satisfied. An execution pipeline executes the no-operation microinstruction or the set of microinstructions. The predictor translates into a second set of one or more microinstructions to conditionally perform the operation when the prediction does not make a prediction.

Abstract: Embodiments relate to branch prediction table install source tracking. An aspect includes a system for branch prediction table install source tracking. The system includes memory configured to store instructions accessible by a processor. The processor includes a branch target buffer, where the processor is configured to perform a method. The method includes receiving at the branch target buffer a request to install a branch target buffer entry corresponding to a branch instruction for branch prediction, and identifying a source of the request as an install source of the branch target buffer entry. The method further includes storing an install source identifier in the branch target buffer based on the install source.