Abstract: Mechanisms are provided for optimizing regular memory references in computer code. These mechanisms may parse the computer code to identify memory references in the computer code. These mechanisms may further classify the memory references in the computer code as either regular memory references or irregular memory references. Moreover, the mechanisms may transform the computer code, by a compiler, to generate transformed computer code in which regular memory references access a storage of a software cache of a data processing system through a high locality cache mechanism of the software cache.

Abstract: Target memory hierarchy specification in a multi-core computer processing system is provided including a system for implementing prefetch instructions. The system includes a first core processor, a dedicated cache corresponding to the first core processor, and a second core processor. The second core processor includes instructions for executing a prefetch instruction that specifies a memory location and the dedicated local cache corresponding to the first core processor. Executing the prefetch instruction includes retrieving data from the memory location and storing the retrieved data on the dedicated local cache corresponding to the first core processor.

Abstract: A monitor bit per hardware thread in a memory location may be allocated, in a multiprocessing computer system having a plurality of hardware threads, the plurality of hardware threads sharing the memory location, and each of the allocated monitor bit corresponding to one of the plurality of hardware threads. A condition bit may be allocated for each of the plurality of hardware threads, the condition bit being allocated in each context of the plurality of hardware threads. In response to detecting the memory location being accessed, it is determined whether a monitor bit corresponding to a hardware thread in the memory location is set. In response to determining that the monitor bit corresponding to a hardware thread is set in the memory location, a condition bit corresponding to a thread accessing the memory location is set in the hardware thread's context.

Abstract: This disclosure describes a method and system that may enable fast, hardware-assisted, producer-consumer style communication of values between threads. The method, in one aspect, uses a dedicated hardware buffer as an intermediary storage for transferring values from registers in one thread to registers in another thread. The method may provide a generic, programmable solution that can transfer any subset of register values between threads in any given order, where the source and target registers may or may not be correlated. The method also may allow for determinate access times, since it completely bypasses the memory hierarchy. Also, the method is designed to be lightweight, focusing on communication, and keeping synchronization facilities orthogonal to the communication mechanism. It may be used by a helper thread that performs data prefetching for an application thread, for example, to initialize the upward-exposed reads in the address computation slice of the helper thread code.

Abstract: Prefetching irregular memory references into a software controlled cache is provided. A compiler analyzes source code to identify at least one of a plurality of loops that contain an irregular memory reference. The compiler determines if the irregular memory reference within the at least one loop is a candidate for optimization. Responsive to an indication that the irregular memory reference may be optimized, the compiler determines if the irregular memory reference is valid for prefetching. Responsive to an indication that the irregular memory reference is valid for prefetching, a store statement for an address of the irregular memory reference is inserted into the at least one loop. A runtime library call is inserted into a prefetch runtime library for the irregular memory reference. Data associated with the irregular memory reference is prefetched into the software controlled cache when the runtime library call is invoked.

Abstract: Prefetching irregular memory references into a software controlled cache is provided. A compiler analyzes source code to identify at least one of a plurality of loops that contain an irregular memory reference. The compiler determines if the irregular memory reference within the at least one loop is a candidate for optimization. Responsive to an indication that the irregular memory reference may be optimized, the compiler determines if the irregular memory reference is valid for prefetching. Responsive to an indication that the irregular memory reference is valid for prefetching, a store statement for an address of the irregular memory reference is inserted into the at least one loop. A runtime library call is inserted into a prefetch runtime library for the irregular memory reference. Data associated with the irregular memory reference is prefetched into the software controlled cache when the runtime library call is invoked.

Abstract: A compiler implemented software cache in which non-aliased explicitly fetched data are excluded are provided. With the mechanisms of the illustrative embodiments, a compiler uses a forward data flow analysis to prove that there is no alias between the cached data and explicitly fetched data. Explicitly fetched data that has no alias in the cached data are excluded from the software cache. Explicitly fetched data that has aliases in the cached data are allowed to be stored in the software cache. In this way, there is no runtime overhead to maintain the correctness of the two copies of data. Moreover, the number of lines of the software cache that must be protected from eviction is decreased. This leads to a decrease in the amount of computation cycles required by the cache miss handler when evicting cache lines during cache miss handling.

Abstract: Dynamically controlling a prefetching range of a software controlled cache is provided. A compiler analyzes source code to identify at least one of a plurality of loops that contain irregular memory references. For each irregular memory reference in the source code, the compiler determines whether the irregular memory reference is a candidate for optimization. Responsive to identifying an irregular memory reference that may be optimized, the complier determines whether the irregular memory reference is valid for prefetching. If the irregular memory reference is valid for prefetching, a store statement for an address of the irregular memory reference is inserted into the at least one loop. A runtime library call is inserted into a prefetch runtime library to dynamically prefetch the irregular memory references. Data associated with the irregular memory references are dynamically prefetched into the software controlled cache when the runtime library call is invoked.

Abstract: A monitor bit per hardware thread in a memory location may be allocated, in a multiprocessing computer system having a plurality of hardware threads, the plurality of hardware threads sharing the memory location, and each of the allocated monitor bit corresponding to one of the plurality of hardware threads. A condition bit may be allocated for each of the plurality of hardware threads, the condition bit being allocated in each context of the plurality of hardware threads. In response to detecting the memory location being accessed, it is determined whether a monitor bit corresponding to a hardware thread in the memory location is set. In response to determining that the monitor bit corresponding to a hardware thread is set in the memory location, a condition bit corresponding to a thread accessing the memory location is set in the hardware thread's context.

Abstract: This disclosure describes a method and system that may enable fast, hardware-assisted, producer-consumer style communication of values between threads. The method, in one aspect, uses a dedicated hardware buffer as an intermediary storage for transferring values from registers in one thread to registers in another thread. The method may provide a generic, programmable solution that can transfer any subset of register values between threads in any given order, where the source and target registers may or may not be correlated. The method also may allow for determinate access times, since it completely bypasses the memory hierarchy. Also, the method is designed to be lightweight, focusing on communication, and keeping synchronization facilities orthogonal to the communication mechanism. It may be used by a helper thread that performs data prefetching for an application thread, for example, to initialize the upward-exposed reads in the address computation slice of the helper thread code.

Abstract: Reducing cache pollution of a software controlled cache is provided. A request is received to prefetch data into the software controlled cache. A first designator is set for a first cache access to a first value. If there is the second cache access to prefetch, a determination is made as to whether data associated with the second cache access exists in the software controlled cache. If the data is in the software controlled cache, a determination is made as to whether a second value of a second designator is greater than the first value of the first cache access. If the second value fails to be greater than the first value, the position of the first cache access and the second cache access in a cache line is swapped. The first value is decremented by a predetermined amount and the second value is replaced to equal the first value.

Abstract: An illustrative embodiment provides a computer-implemented process for managing speculative assist threads for data pre-fetching that analyzes collected source code and cache profiling information to identify a code region containing a delinquent load instruction and generates an assist thread, including a value for a local version number, at a program entry point within the identified code region. Upon activation of the assist thread the local version number of the assist thread is compared to the global unique version number of the main thread for the identified code region and an iteration distance between the assist thread relative to the main thread is compared to a predefined value. The assist thread is executed when the local version number of the assist thread matches the global unique version number of the main thread, and the iteration distance between the assist thread relative to the main thread is within a predefined range of values.

Abstract: A compiler implemented software cache is provided in which non-aliased explicitly fetched data are excluded are provided. With the mechanisms of the illustrative embodiments, a compiler uses a forward data flow analysis to prove that there is no alias between the cached data and explicitly fetched data. Explicitly fetched data that has no alias in the cached data are excluded from the software cache. Explicitly fetched data that has aliases in the cached data are allowed to be stored in the software cache. In this way, there is no runtime overhead to maintain the correctness of the two copies of data. Moreover, the number of lines of the software cache that must be protected from eviction is decreased. This leads to a decrease in the amount of computation cycles required by the cache miss handler when evicting cache lines during cache miss handling.

Abstract: Mechanisms for optimized code generation targeting a high locality software cache are provided. Original computer code is parsed to identify memory references in the original computer code. Memory references are classified as either regular memory references or irregular memory references. Regular memory references are controlled by a high locality cache mechanism. Original computer code is transformed, by a compiler, to generate transformed computer code in which the regular memory references are grouped into one or more memory reference streams, each memory reference stream having a leading memory reference, a trailing memory reference, and one or more middle memory references.

Abstract: Dynamically controlling a prefetching range of a software controlled cache is provided. A compiler analyzes source code to identify at least one of a plurality of loops that contain irregular memory references. For each irregular memory reference in the source code, the compiler determines whether the irregular memory reference is a candidate for optimization. Responsive to identifying an irregular memory reference that may be optimized, the complier determines whether the irregular memory reference is valid for prefetching. If the irregular memory reference is valid for prefetching, a store statement for an address of the irregular memory reference is inserted into the at least one loop. A runtime library call is inserted into a prefetch runtime library to dynamically prefetch the irregular memory references. Data associated with the irregular memory references are dynamically prefetched into the software controlled cache when the runtime library call is invoked.

Abstract: Prefetching irregular memory references into a software controlled cache is provided. A compiler analyzes source code to identify at least one of a plurality of loops that contain an irregular memory reference. The compiler determines if the irregular memory reference within the at least one loop is a candidate for optimization. Responsive to an indication that the irregular memory reference may be optimized, the compiler determines if the irregular memory reference is valid for prefetching. Responsive to an indication that the irregular memory reference is valid for prefetching, a store statement for an address of the irregular memory reference is inserted into the at least one loop. A runtime library call is inserted into a prefetch runtime library for the irregular memory reference. Data associated with the irregular memory reference is prefetched into the software controlled cache when the runtime library call is invoked.

Abstract: Reducing cache pollution of a software controlled cache is provided. A request is received to prefetch data into the software controlled cache. A first designator is set for a first cache access to a first value. If there is the second cache access to prefetch, a determination is made as to whether data associated with the second cache access exists in the software controlled cache. If the data is in the software controlled cache, a determination is made as to whether a second value of a second designator is greater than the first value of the first cache access. If the second value fails to be greater than the first value, the position of the first cache access and the second cache access in a cache line is swapped. The first value is decremented by a predetermined amount and the second value is replaced to equal the first value.

Abstract: Mechanisms are provided for optimizing regular memory references in computer code. These mechanisms may parse the computer code to identify memory references in the computer code. These mechanisms may further classify the memory references in the computer code as either regular memory references or irregular memory references. Moreover, the mechanisms may transform the computer code, by a compiler, to generate transformed computer code in which regular memory references access a storage of a software cache of a data processing system through a high locality cache mechanism of the software cache.

Abstract: Mechanisms are provided for optimizing irregular memory references in computer code. These mechanisms may parse the computer code to identify memory references in the computer code. These mechanisms may further classify the memory references in the computer code as either regular memory references or irregular memory references. Moreover, the mechanisms may transform the computer code, by a compiler, to generate transformed computer code in which irregular memory references access a storage of a software cache of a data processing system through a transactional cache mechanism of the software cache.

Abstract: A compiler implemented software cache apparatus and method in which non-aliased explicitly fetched data are excluded are provided. With the mechanisms of the illustrative embodiments, a compiler uses a forward data flow analysis to prove that there is no alias between the cached data and explicitly fetched data. Explicitly fetched data that has no alias in the cached data are excluded from the software cache. Explicitly fetched data that has aliases in the cached data are allowed to be stored in the software cache. In this way, there is no runtime overhead to maintain the correctness of the two copies of data. Moreover, the number of lines of the software cache that must be protected from eviction is decreased. This leads to a decrease in the amount of computation cycles required by the cache miss handler when evicting cache lines during cache miss handling.