Abstract: A computer readable storage medium is provided having executable instructions stored thereon for executing a method of operating a computing system, in which an inner virtual machine translates first instructions, which are supported by the inner virtual machine, into second instructions, which are supported by an outer virtual machine. The method includes encoding, in the inner virtual machine, third instructions into the second instructions into which the first instructions are translated, the third instructions including hints for facilitating an execution of the second instructions, and, in an event the hints are supported by the outer virtual machine, initiating the execution of the second instructions while utilizing the hints by the outer virtual machine to achieve an increased efficiency of the execution of the second instructions.

Abstract: A method of utilizing registers in a processor device is provided. The method includes: determining a first operand based on an operand notation indicating a subset of high-order bits of a first register, the first register having a total of sixty-four bits; determining a second operand based on an operand notation indicating at least one of a subset of high-order bits of a second register and a subset of low-order bits of the second register, the second register having a total of sixty-four bits; performing an operation based on the first operand and the second operand; and updating at least one of the first register and the second register based on a result of the operation, and wherein the high-order bits include bits that are greater than thirty-two, and wherein the low-order bits include bits that are less than or equal to thirty-two.

Abstract: A handle for a trace is provided that is memory indifferent. The handle is created using contents of the trace rather than memory location of the trace. This enables the trace to be easily identified in subsequent runs of an application associated with the trace.

Abstract: A handle for a trace is provided that is memory indifferent. The handle is created using contents of the trace rather than memory location of the trace. This enables the trace to be easily identified in subsequent runs of an application associated with the trace.

Abstract: Nested virtual machines cooperate with one another to improve system performance. In particular, an outer virtual machine performs tasks on behalf of an inner virtual machine to improve system performance. One such task includes translation of instructions for the inner virtual machine.

Abstract: Illustrative embodiments provide a computer implemented method, an apparatus in the form of a data processing system and a computer program product for cache line reservations. In one embodiment, the computer implemented method comprises, dividing a memory into an unreserved section and a set of reserved sections. The method performs selected allocations of the memory only from the set of reserved sections, and performing un-selected allocations of the memory from the unreserved section. The method further mapping a specified selected allocation of the memory to a same corresponding line of cache memory each time the mapping for the specified selected allocation of the memory occurs, thereby maintaining locality.

Abstract: Prior art attempts to provide 32-bit addressing within a 64-bit computing environment lead to other complications. Hardware solutions result in more complicated hardware which, in turn, increases costs and may reduce the functionality of 64-bit computing and significant changes to commercially available 64-bit processors. Alternatively, previous software solutions are computationally expensive, requiring add and subtract routines convert between 32-bit addresses and 64-bit addresses. An additional problem, specific to IBM™ zSeries hardware, is that the only way to provide a heap size larger than 2 GB, even if less than 4 GB, is to employ the 64-bit addressing in combination with a computationally expensive software patch to emulate 32-bit addressing. By contrast, provided by aspects of the present invention there are systems, methods and computer program products for implementing low-cost pointer compression and decompression.

Abstract: Systems, methods, and computer products for evaluating robustness of a list scheduling framework. Exemplary embodiments include a method for evaluating the robustness of a list scheduling framework, the method including identifying a set of compiler benchmarks known to be sensitive to an instruction scheduler, running the set of benchmarks against a heuristic under test, H and collect an execution time Exec(H[G]), where G is a directed a-cyclical graph, running the set of benchmarks against a plurality of random heuristics Hrand[G]i, and collect a plurality of respective execution times Exec(Hrand[G])i, computing a robustness of the list scheduling framework, and checking robustness check it against a pre-determined threshold.

Abstract: Assigning each of a plurality of memory fetch units to any of a plurality of candidate variables to reduce load-hit-store delays, wherein a total number of required memory fetch units is minimized. A plurality of store/load pairs are identified. A dependency graph is generated by creating a node Nx for each store to variable X and a node Ny for each load of variable Y and, unless X=Y, for each store/load pair, creating an edge between a respective node Nx and a corresponding node Ny; for each created edge, labeling the edge with a heuristic weight; labeling each node Nx with a node weight Wx that combines a plurality of respective edge weights of a plurality of corresponding nodes Nx such that Wx=??xj; and determining a color for each of the graph nodes using k distinct colors wherein k is minimized such that no adjacent nodes joined by an edge between a respective node Nx and a corresponding node Ny have an identical color; and assigning a memory fetch unit to each of the k distinct colors.

Abstract: Tracing within a processing environment is controlled. Trace directives are automatically included within code being compiled in order to control where one or more traces begin and end within the code. The trace directives provide a framework for mapping traces to well understood boundaries of the code.

Abstract: There is disclosed a method and system for configuring a data dependency graph (DDG) to handle instruction scheduling in computer architectures permitting dynamic by-pass execution, and for performing dynamic by-pass scheduling utilizing such a configured DDG. In accordance with an embodiment of the invention, a heuristic function is used to obtain a ranking of nodes in the DDG after setting delays at all identified by-pass pairs of nodes in the DDG to 0. From among a list of identified by-pass pairs of nodes, a node that is identified as being the least important to schedule early is marked as “bonded” to its successor, and the corresponding delay for that identified node is set to 0. Node rankings are re-computed and the bonded by-pass pair of nodes are scheduled in consecutive execution cycles with a delay of 0 to increase the likelihood that a by-pass can be successfully taken during run-time execution.

Abstract: A handle for a trace is provided that is memory indifferent. The handle is created using contents of the trace rather than memory location of the trace. This enables the trace to be easily identified in subsequent runs of an application associated with the trace.

Abstract: Automatic inspection of compiled code. In response to revising a compiler, the functionality of that compiler is verified. Specific code is compiled using a first version of the compiler, as well as a second version of the compiler. Each compiled code is then applied to machine state to obtain multiple machine states. The machine states are then compared to determine if they are equal.

Abstract: There is disclosed a method and system for configuring a data dependency graph (DDG) to handle instruction scheduling in computer architectures permitting dynamic by-pass execution, and for performing dynamic by-pass scheduling utilizing such a configured DDG. In accordance with an embodiment of the invention, a heuristic function is used to obtain a ranking of nodes in the DDG after setting delays at all identified by-pass pairs of nodes in the DDG to 0. From among a list of identified by-pass pairs of nodes, a node that is identified as being the least important to schedule early is marked as “bonded” to its successor, and the corresponding delay for that identified node is set to 0. Node rankings are re-computed and the bonded by-pass pair of nodes are scheduled in consecutive execution cycles with a delay of 0 to increase the likelihood that a by-pass can be successfully taken during run-time execution.

Abstract: Expressions are selectively retrieved from memory during compilation by scanning code for expressions that can be effectively accessed directly from highly cached memory without needing to be loaded into a register, e.g., expressions that are not modified by the rest of the code. The scanning may include examining the use of the expression. Those expressions may be retrieved directly from the highly cached memory rather than being loaded into registers. This reduces compilation time.

Abstract: A computer implemented method, system, and computer usable program code for selective instruction scheduling. A determination is made whether a region of code exceeds a modification threshold after performing register allocation on the region of code. The region of code is marked as a modified region of code in response to the determination that the region of code exceeds the modification threshold. A determination is made whether the region of code exceeds an execution threshold in response to the determination that the region of code is marked as a modified region of code. Post-register allocation instruction scheduling is performed on the region of code in response to the determination that the region of code is marked as a modified region of code and the determination that the region of code exceeds the execution threshold.

Abstract: There is disclosed a method and system for configuring a data dependency graph (DDG) to handle instruction scheduling in computer architectures permitting dynamic by-pass execution, and for performing dynamic by-pass scheduling utilizing such a configured DDG. In accordance with an embodiment of the invention, a heuristic function is used to obtain a ranking of nodes in the DDG after setting delays at all identified by-pass pairs of nodes in the DDG to 0. From among a list of identified by-pass pairs of nodes, a node that is identified as being the least important to schedule early is marked as “bonded” to its successor, and the corresponding delay for that identified node is set to 0. Node rankings are re-computed and the bonded by-pass pair of nodes are scheduled in consecutive execution cycles with a delay of 0 to increase the likelihood that a by-pass can be successfully taken during run-time execution.