Abstract: Embodiments related to selecting a runahead poison policy from a plurality of runahead poison policies during microprocessor operation are provided. The example method includes causing the microprocessor to enter runahead upon detection of a runahead event and implementing a first runahead poison policy selected from a plurality of runahead poison policies operative to manage runahead poison injection during runahead. The example method also includes during microprocessor operation, selecting a second runahead poison policy operative to manage runahead poison injection differently from the first runahead poison policy.

Abstract: Embodiments related to selecting a runahead poison policy from a plurality of runahead poison policies during microprocessor operation are provided. The example method includes causing the microprocessor to enter runahead upon detection of a runahead event and implementing a first runahead poison policy selected from a plurality of runahead poison policies operative to manage runahead poison injection during runahead. The example method also includes during microprocessor operation, selecting a second runahead poison policy operative to manage runahead poison injection differently from the first runahead poison policy.

Abstract: Embodiments related to selecting a runahead poison policy from a plurality of runahead poison policies during microprocessor operation are provided. The example method includes causing the microprocessor to enter runahead upon detection of a runahead event and implementing a first runahead poison policy selected from a plurality of runahead poison policies operative to manage runahead poison injection during runahead. The example method also includes during microprocessor operation, selecting a second runahead poison policy operative to manage runahead poison injection differently from the first runahead poison policy.

Abstract: Embodiments related to managing lazy runahead operations at a microprocessor are disclosed. For example, an embodiment of a method for operating a microprocessor described herein includes identifying a primary condition that triggers an unresolved state of the microprocessor. The example method also includes identifying a forcing condition that compels resolution of the unresolved state. The example method also includes, in response to identification of the forcing condition, causing the microprocessor to enter a runahead mode.

Abstract: Embodiments related to re-dispatching an instruction selected for re-execution from a buffer upon a microprocessor re-entering a particular execution location after runahead are provided. In one example, a microprocessor is provided. The example microprocessor includes fetch logic, one or more execution mechanisms for executing a retrieved instruction provided by the fetch logic, and scheduler logic for scheduling the retrieved instruction for execution. The example scheduler logic includes a buffer for storing the retrieved instruction and one or more additional instructions, the scheduler logic being configured, upon the microprocessor re-entering at a particular execution location after runahead, to re-dispatch, from the buffer, an instruction that has been previously dispatched to one of the execution mechanisms.

Abstract: Various embodiments of microprocessors and methods of operating a microprocessor during runahead operation are disclosed herein. One example method of operating a microprocessor includes identifying a runahead-triggering event associated with a runahead-triggering instruction and, responsive to identification of the runahead-triggering event, entering runahead operation and inserting the runahead-triggering instruction along with one or more additional instructions in a queue. The example method also includes resuming non-runahead operation of the microprocessor in response to resolution of the runahead-triggering event and re-dispatching the runahead-triggering instruction along with the one or more additional instructions from the queue to the execution logic.

Abstract: Embodiments related to managing potentially invalid results generated/obtained by a microprocessor during runahead are provided. In one example, a method for operating a microprocessor includes causing the microprocessor to enter runahead upon detection of a runahead event. The example method also includes, during runahead, determining that an operation associated with an instruction referencing a storage location would produce a potentially invalid result based on a value of an architectural poison bit associated with the storage location and performing a different operation in response.

Abstract: Embodiments related to managing lazy runahead operations at a microprocessor are disclosed. For example, an embodiment of a method for operating a microprocessor described herein includes identifying a primary condition that triggers an unresolved state of the microprocessor. The example method also includes identifying a forcing condition that compels resolution of the unresolved state. The example method also includes, in response to identification of the forcing condition, causing the microprocessor to enter a runahead mode.

Abstract: In a processor, a method for speculative permission acquisition for access to a shared memory. The method includes receiving a store from a processor core to modify a shared cache line, and in response to receiving the store, marking the cache line as speculative. The cache line is then modified in accordance with the store. Upon receiving a modification permission, the modified cache line is subsequently committed.

Abstract: Embodiments related to managing lazy runahead operations at a microprocessor are disclosed. For example, an embodiment of a method for operating a microprocessor described herein includes identifying a primary condition that triggers an unresolved state of the microprocessor. The example method also includes identifying a forcing condition that compels resolution of the unresolved state. The example method also includes, in response to identification of the forcing condition, causing the microprocessor to enter a runahead mode.

Abstract: Method and system for supporting speculative modification in a data cache are provided and described. In one embodiment, a speculative cache buffer includes a plurality of cache lines and a plurality of state indicators. At least one of the cache lines is operable to receive an evicted cache line from a cache. The at least one of the cache lines is operable to return the evicted cache line to the cache if the cache requests the evicted cache line. Further, the plurality of state indicators is operable to indicate a state of a corresponding cache line of the cache lines.

Abstract: Various embodiments of microprocessors and methods of operating a microprocessor during runahead operation are disclosed herein. One example method of operating a microprocessor includes identifying a runahead-triggering event associated with a runahead-triggering instruction and, responsive to identification of the runahead-triggering event, entering runahead operation and inserting the runahead-triggering instruction along with one or more additional instructions in a queue. The example method also includes resuming non-runahead operation of the microprocessor in response to resolution of the runahead-triggering event and re-dispatching the runahead-triggering instruction along with the one or more additional instructions from the queue to the execution logic.

Abstract: Embodiments related to managing lazy runahead operations at a microprocessor are disclosed. For example, an embodiment of a method for operating a microprocessor described herein includes identifying a primary condition that triggers an unresolved state of the microprocessor. The example method also includes identifying a forcing condition that compels resolution of the unresolved state. The example method also includes, in response to identification of the forcing condition, causing the microprocessor to enter a runahead mode.

Abstract: Embodiments related to methods and devices operative, in the event that execution of an instruction produces a runahead-triggering event, to cause a microprocessor to enter into and operate in a runahead without reissuing the instruction are provided. In one example, a microprocessor is provided. The example microprocessor includes fetch logic for retrieving an instruction, scheduling logic for issuing the instruction retrieved by the fetch logic for execution, and runahead control logic. The example runahead control logic is operative, in the event that execution of the instruction as scheduled by the scheduling logic produces a runahead-triggering event, to cause the microprocessor to enter into and operate in a runahead mode without reissuing the instruction, and carry out runahead policies while the microprocessor is in the runahead mode that governs operation of the microprocessor and cause the microprocessor to operate differently than when not in the runahead mode.

Abstract: Embodiments related to managing potentially invalid results generated/obtained by a microprocessor during runahead are provided. In one example, a method for operating a microprocessor includes causing the microprocessor to enter runahead upon detection of a runahead event. The example method also includes, during runahead, determining that an operation associated with an instruction referencing a storage location would produce a potentially invalid result based on a value of an architectural poison bit associated with the storage location and performing a different operation in response.

Abstract: Embodiments related to selecting a runahead poison policy from a plurality of runahead poison policies during microprocessor operation are provided. The example method includes causing the microprocessor to enter runahead upon detection of a runahead event and implementing a first runahead poison policy selected from a plurality of runahead poison policies operative to manage runahead poison injection during runahead. The example method also includes during microprocessor operation, selecting a second runahead poison policy operative to manage runahead poison injection differently from the first runahead poison policy.

Abstract: In a processor, a method for speculative permission acquisition for access to a shared memory. The method includes receiving a store from a processor core to modify a shared cache line, and in response to receiving the store, marking the cache line as speculative. The cache line is then modified in accordance with the store. Upon receiving a modification permission, the modified cache line is subsequently committed.

Abstract: Embodiments related to re-dispatching an instruction selected for re-execution from a buffer upon a microprocessor re-entering a particular execution location after runahead are provided. In one example, a microprocessor is provided. The example microprocessor includes fetch logic, one or more execution mechanisms for executing a retrieved instruction provided by the fetch logic, and scheduler logic for scheduling the retrieved instruction for execution. The example scheduler logic includes a buffer for storing the retrieved instruction and one or more additional instructions, the scheduler logic being configured, upon the microprocessor re-entering at a particular execution location after runahead, to re-dispatch, from the buffer, an instruction that has been previously dispatched to one of the execution mechanisms.

Abstract: Instructions asserted in the instruction pipeline of the microprocessor are accompanied by control information, comprising a group of bits, asserted within a control information pipeline of the processor. The control information pipeline is synchronized to the instruction pipeline so that the control information for an instruction progresses in synchronism with the instruction. The control information may identify, directly or indirectly, the type of operation called for by the instruction and, if the operation is to be performed in parts, indicate the part to be performed. Means are included in the processor, such as a number of functional execution units, to interpret that control information and take appropriate action.

Abstract: Instructions asserted in the instruction pipeline of the microprocessor are accompanied by control information, comprising a group of bits, asserted within a control information pipeline of the processor. The control information pipeline is synchronized to the instruction pipeline so that the control information for an instruction progresses in synchronism with the instruction. The control information may identify, directly or indirectly, the type of operation called for by the instruction and, if the operation is to be performed in parts, indicate the part to be performed. Means are included in the processor, such as a number of functional execution units, to interpret that control information and take appropriate action.