摘要:
Optimizations are programmatically applied by a compiler (preferably, a just-in-time or “JIT” compiler), and enable achieving improved performance while a variable acts as a global constant, yet also allow code to execute correctly if the global constant's run-time value changes from the value on which the optimization was originally based. Code snippets that dynamically patch executable code are described, where these code snippets take corrective actions to enable correct program execution following a run-time change to the value of a glacial constant. A backup recovery path may also be maintained, where this path provides code that is executed in the event of a change to a glacial constant and that treats the glacial constant as a variable. Recompilation may also be used after a change to a glacial constant, where the originally-compiled code has made an assumption about the glacial constant's value that is no longer accurate. Combinations of these approaches may be used.
摘要:
Under the present invention, a locking primitive associated with a shared data object is automatically transformed to allow multiple read-only locks if certain conditions are met. To this extent, when a read-only lock on a shared data object is desired, a thread identifier of an object header lock word (hereinafter “lock word”) associated with the shared data object is examined to determine if a read-write lock on the shared data object already exists. If not, then the thread identifier is set to a predetermined value indicative of read-only locks, and a thread count in the lock word is incremented. If another thread attempts a read-only lock, the thread identifier will be examined for the predetermined value. If it is present, the thread count will be incremented again, and a second read-only lock will be simultaneously established.
摘要:
An aspect includes enabling and disabling execution of a run-time instrumentation facility. An instruction for execution by the processor in a lesser privileged state is fetched by the processor. The instruction is executed based on determining, by the processor, that the run-time instrumentation facility permits execution of the instruction in the lesser-privileged state and that controls associated with the run-time instrumentation facility are valid. The run-time instrumentation facility is disabled based on the instruction being a run-time instrumentation facility off (RIOFF) instruction. The disabling includes updating a bit in a program status word (PSW) of the processor to indicate that run-time instrumentation data should not be captured by the processor. The run-time instrumentation facility is enabled based on the instruction being a run-time instrumentation facility on (RION) instruction. The enabling includes updating the bit in the PSW to indicate that run-time instrumentation data should be captured by the processor.
摘要:
A mechanism is provided for 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 mechanism encodes, 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.
摘要:
Optimizing a program having a plurality of functions. The program is optimized using an optimization technique that requires breaking a calling convention. The first function of the plurality of functions is modified as a result of optimizing. A name of the first function is mangled to form a unique first mangled name. Mangling comprises changing the name. The unique first mangled name includes, as a result of mangling, first information conveying at least in part how the first function was modified. A second function of the plurality of functions, being a caller of the first function, is also modified to correctly invoke first function using the unique first mangled name to apply the optimization technique. A compilation tool can, after optimizing, use the first information to take a first action with respect to the first procedure, wherein the compilation tool otherwise would require the calling convention to remain unbroken in order to take the first action.
摘要:
In the field of mixed 16-bit and 32-bit code, a method and mechanism are provided to implement alterations in the dynamic portion of memory containing the data objects used by code in the 16-bit environment so that such data is accessible to code from the 32-bit environment. The code necessary to implement the method is generated automatically by an enhanced compiler on identifying 16-bit linkage in the 32-bit code. Once the data objects in the stack are accesible to the 32-bit code, a function in the 16-bit code can successfully call a function in 32-bit code.
摘要:
Embodiments of the invention relate to enabling and disabling execution of a run-time instrumentation facility. An instruction for execution by the processor in a lesser privileged state is fetched by the processor. It is determined, by the processor, that the run-time instrumentation facility permits execution of the instruction in the lesser-privileged state and that controls associated with the run-time instrumentation facility are valid. The run-time instrumentation facility is disabled based on the instruction being a run-time instrumentation facility off (RIOFF) instruction. The disabling includes updating a bit in a program status word (PSW) of the processor to indicate that run-time instrumentation data should not be captured by the processor. The run-time instrumentation facility is enabled based on the instruction being a run-time instrumentation facility on (RION) instruction. The enabling includes updating the bit in the PSW to indicate that run-time instrumentation data should be captured by the processor.
摘要:
Embodiments of the present invention address deficiencies of the art in respect to pattern matcher generation and provide a method, system and computer program product for automatic pattern matching and generation of intermediate language patterns. In one embodiment of the invention, a pattern matcher generation method can be provided. The method can include identifying input elements from intermediate language code, reducing the identified input elements from the intermediate language code to inputs of common and unique use, creating a unifiable form for each of the input elements of common and unique use, and generating a pattern matcher for each of the input elements of common and unique use in the intermediate language code using a corresponding unifiable form in place of each of the input elements of common and unique use. In particular, the generated pattern matcher can be EMTF conformant.
摘要:
Aspects of the invention relate to executing a run-time-instrumentation EMIT (RIEMIT) instruction. A processor is configured to capture the run-time-instrumentation information of a stream of instructions. The RIEMIT instruction is fetched and executed. It is determined if the current run-time-instrumentation controls are configured to permit capturing and storing of run-time-instrumentation information in a run-time-instrumentation program buffer. If the controls are configured to store run-time-instrumentation instructions, then a RIEMIT instruction specified value is stored as an emit record of a reporting group in the run-time-instrumentation program buffer.
摘要:
Optimizing a program having a plurality of functions using an optimization technique that requires breaking a calling convention. A first function of the plurality of functions is modified as a result of optimizing. A name of the first function is mangled to form a unique first mangled name changing the name of the first function to include, as a result of mangling, first information conveying at least in part how the first function was modified. A second function of the plurality of functions, being a caller of the first function, is also modified to correctly invoke the first function using the unique first mangled name to apply the optimization technique. A compilation tool can, after optimizing, use the first information to take a first action with respect to the first procedure, wherein the compilation tool otherwise would require the calling convention to remain unbroken to take the first action.