摘要:
An apparatus and method is described herein for providing speculation control instructions. An xAcquire and xRelease instruction are provided to define a critical section. In one embodiment, the xAcquire instruction includes a lock instruction with an elision prefix and the xRelease instruction includes a lock release instruction with an elision prefix. As a result, a processor is able to elide locks and transactionally execute a critical section defined in software by xAcquire and xRelease. But by adding only prefix hints, legacy processor are able to execute the same code by just ignoring the hints and executing the critical section traditionally with locks to guarantee mutual exclusion. Moreover, xBegin and xEnd are similarly provided for in an Instruction Set Architecture (ISA) to define a transactional code region. In addition, other control speculation instructions, such as xAbort to enable explicit abort of a critical or transactional code section and xTest to test a state of speculative execution is also provided in the ISA.
摘要:
Novel instructions, logic, methods and apparatus are disclosed to test transactional execution status. Embodiments include decoding a first instruction to start a transactional region. Responsive to the first instruction, a checkpoint for a set of architecture state registers is generated and memory accesses from a processing element in the transactional region associated with the first instruction are tracked. A second instruction to detect transactional execution of the transactional region is then decoded. An operation is executed, responsive to decoding the second instruction, to determine if an execution context of the second instruction is within the transactional region. Then responsive to the second instruction, a first flag is updated. In some embodiments, a register may optionally be updated and/or a second flag may optionally be updated responsive to the second instruction.
摘要:
Novel instructions, logic, methods and apparatus are disclosed to test transactional execution status. Embodiments include decoding a first instruction to start a transactional region. Responsive to the first instruction, a checkpoint for a set of architecture state registers is generated and memory accesses from a processing element in the transactional region associated with the first instruction are tracked. A second instruction to detect transactional execution of the transactional region is then decoded. An operation is executed, responsive to decoding the second instruction, to determine if an execution context of the second instruction is within the transactional region. Then responsive to the second instruction, a first flag is updated. In some embodiments, a register may optionally be updated and/or a second flag may optionally be updated responsive to the second instruction.
摘要:
A secondary jump execution unit (JEU) is incorporated in a micro-processor to operate concurrently with a primary JEU, enabling the execution of simultaneous branch operations with possible detection of multiple branch mispredicts. When branch operations are executed on both JEUs in a same instruction cycle, mispredict processing for the secondary JEU is skidded into the primary JEU's dispatch pipeline such that the branch processing for the secondary JEU occurs after processing of the branch for the primary JEU and while the primary JEU is not processing a branch. Moreover, in cases when a nuke command is also received from a reorder buffer of the processor, the branch processing for the secondary JEU is further delayed to accommodate processing of the nuke on the primary JEU. Further embodiments support the promotion of the secondary JEU to have access to the mispredict mechanisms of the primary JEU in certain circumstances.
摘要:
An enhanced loop streaming detection mechanism is provided in a processor to reduce power consumption. The processor includes a decoder to decode instructions in a loop into micro-operations, and a loop streaming detector to detect the presence of the loop in the micro-operations. The processor also includes a loop characteristic tracker unit to identify hardware components downstream from the decoder that are not to be used by the micro-operations in the loop, and to disable the identified hardware components. The processor also includes execution circuitry to execute the micro-operations in the loop with the identified hardware components disabled.
摘要:
An enhanced loop streaming detection mechanism is provided in a processor to reduce power consumption. The processor includes a decoder to decode instructions in a loop into micro-operations, and a loop streaming detector to detect the presence of the loop in the micro-operations. The processor also includes a loop characteristic tracker unit to identify hardware components downstream from the decoder that are not to be used by the micro-operations in the loop, and to disable the identified hardware components. The processor also includes execution circuitry to execute the micro-operations in the loop with the identified hardware components disabled.
摘要:
Apparatuses and methods for dead instruction identification are disclosed. In one embodiment, an apparatus includes an instruction buffer and a dead instruction identifier. The instruction buffer is to store an instruction stream having a single entry point and a single exit point. The dead instruction identifier is to identify dead instructions based on a forward pass through the instruction stream.
摘要:
A technique for using memory attributes to relay information to a program or other agent. More particularly, embodiments of the invention relate to using memory attribute bits to check various memory properties in an efficient manner.
摘要:
In one embodiment, the present invention includes a predictor to predict contention of an operation to be executed in a program. The operation may be processed based on a result of the prediction, which may be based on multiple independent predictions. In one embodiment, the operation may be optimized if no contention is predicted. Other embodiments are described and claimed.
摘要:
A technique for using memory attributes to relay information to a program or other agent. More particularly, embodiments of the invention relate to using memory attribute bits to check various memory properties in an efficient manner.