Abstract: Embodiments of the invention relate to run-time instrumentation reporting. An instruction stream is executed by a processor. Run-time instrumentation information of the executing instruction stream is captured by the processor. Run-time instrumentation records are created based on the captured run-time instrumentation information. A run-time instrumentation sample point of the executing instruction stream on the processor is detected. A reporting group is stored in a run-time instrumentation program buffer. The storing is based on the detecting and the storing includes: determining a current address of the run-time instrumentation program buffer, the determining based on instruction accessible run-time instrumentation controls; and storing the reporting group into the run-time instrumentation program buffer based on an origin address and the current address of the run-time instrumentation program buffer, the reporting group including the created run-time instrumentation records.

Abstract: A process, a computer program product, and a computer system for efficient code cache management implemented by a just-in-time compiler are provided. Embodiments of the present invention provide a practical approach to compile effectively for methods that are frequently executed over a short time period but are subsequently not executed frequently. The disclosed approach reduces the detrimental effects of compilation of such infrequently executed methods on throughput and garbage collection pause times.

Abstract: One embodiment is a computer-implemented method for safe conditional operation when storage access cannot be proven safe. The method includes receiving a portion of source code for a transaction by an enhanced compiler and. The portion of source code received is analyzed, by the enhanced compiler, to determine whether the portion of source code is a candidate for transformation. Responsive to a determination that the portion of source code analyzed by the enhanced compiler is a candidate for transformation, the portion of the source code analyzed is transformed, by a computer processor, to use a conditional operation in a first portion of the transformed code. The conditional operation uses hardware transaction memory to invoke retry operations within hardware. A branch is added, directed to an original code portion, in a second portion of transformed code, where the branch is a recovery portion containing the original code portion.

Abstract: An aspect includes run-time instrumentation reporting. An instruction stream is executed by a processor. Run-time instrumentation information of the executing instruction stream is captured by the processor. Run-time instrumentation records are created based on the captured run-time instrumentation information. A run-time instrumentation sample point of the executing instruction stream on the processor is detected. A reporting group is stored in a run-time instrumentation program buffer. The storing is based on the detecting and the storing includes: determining a current address of the run-time instrumentation program buffer, the determining based on instruction accessible run-time instrumentation controls; and storing the reporting group into the run-time instrumentation program buffer based on an origin address and the current address of the run-time instrumentation program buffer, the reporting group including the created run-time instrumentation records.

Abstract: 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.

Abstract: Dynamic creation of a spatially aware emulation environment comprising Host cells of Host pages corresponding to Guest cells of Guest pages of Guest instructions. Each Host cell comprises a semantic routine for emulating a corresponding Guest instruction located at the corresponding Guest cell of the guest page.

Abstract: Embodiments relate to branch prediction preloading. An aspect includes a system for branch prediction preloading. The system includes an instruction cache and branch target buffer (BTB) coupled to a processing circuit, the processing circuit configured to perform a method. The method includes fetching a plurality of instructions in an instruction stream from the instruction cache, and decoding a branch prediction preload instruction in the instruction stream. An address of a predicted branch instruction is determined based on the branch prediction preload instruction. A predicted target address is determined based on the branch prediction preload instruction. A mask field is identified in the branch prediction preload instruction, and a branch instruction length is determined based on the mask field.

Abstract: Embodiments relate to branch prediction preloading. A method for branch prediction preloading includes fetching a plurality of instructions in an instruction stream, and decoding a branch prediction preload instruction in the instruction stream. The method also includes determining, by a processing circuit, an address of a predicted branch instruction based on the branch prediction preload instruction, and determining, by the processing circuit, a predicted target address of the predicted branch instruction based on the branch prediction preload instruction. The method further includes identifying a mask field in the branch prediction preload instruction, and determining, by the processing circuit, a branch instruction length of the predicted branch instruction based on the mask field.

Abstract: A delay facility is provided in which program execution may be delayed until a predefined event occurs, such as a comparison of memory locations results in a true condition, a timeout is reached, an interruption is made pending or another condition exists. The delay facility includes one or more compare and delay machine instructions used to delay execution. The one or more compare and delay instructions may include a 32-bit compare and delay (CAD) instruction and a 64-bit compare and delay (CADG) instruction.

Abstract: A Conditional Transaction End (CTEND) instruction is provided that allows a program executing in a nonconstrained transactional execution mode to inspect a storage location that is modified by either another central processing unit or the Input/Output subsystem. Based on the inspected data, transactional execution may be ended or aborted, or the decision to end/abort may be delayed, e.g., until a predefined event occurs. For instance, when the instruction executes, the processor is in a nonconstrained transaction execution mode, and the transaction nesting depth is one at the beginning of the instruction, a second operand of the instruction is inspected, and based on the inspected data, transaction execution may be ended or aborted, or the decision to end/abort may be delayed, e.g., until a predefined event occurs, such as the value of the second operand becomes a prespecified value or a time interval is exceeded.

Abstract: A conditional instruction end facility is provided that allows completion of an instruction to be delayed. In executing the machine instruction, an operand is obtained, and a determination is made as to whether the operand has a predetermined relationship with respect to a value. Based on determining that the operand does not have the predetermined relationship with respect to the value, the obtaining and the determining are repeated. Based on determining that the operand has the predetermined relationship with respect to the value, execution of the instruction is completed.

Abstract: A delay facility is provided in which program execution may be delayed until a predefined event occurs, such as a comparison of memory locations results in a true condition, a timeout is reached, an interruption is made pending or another condition exists. The delay facility includes one or more compare and delay machine instructions used to delay execution. The one or more compare and delay instructions may include a 32-bit compare and delay (CAD) instruction and a 64-bit compare and delay (CADG) instruction.

Abstract: A Conditional Transaction End (CTEND) instruction is provided that allows a program executing in a nonconstrained transactional execution mode to inspect a storage location that is modified by either another central processing unit or the Input/Output subsystem. Based on the inspected data, transactional execution may be ended or aborted, or the decision to end/abort may be delayed, e.g., until a predefined event occurs. For instance, when the instruction executes, the processor is in a nonconstrained transaction execution mode, and the transaction nesting depth is one at the beginning of the instruction, a second operand of the instruction is inspected, and based on the inspected data, transaction execution may be ended or aborted, or the decision to end/abort may be delayed, e.g., until a predefined event occurs, such as the value of the second operand becomes a prespecified value or a time interval is exceeded.

Abstract: A conditional instruction end facility is provided that allows completion of an instruction to be delayed. In executing the machine instruction, an operand is obtained, and a determination is made as to whether the operand has a predetermined relationship with respect to a value. Based on determining that the operand does not have the predetermined relationship with respect to the value, the obtaining and the determining are repeated. Based on determining that the operand has the predetermined relationship with respect to the value, execution of the instruction is completed.

Abstract: A TRANSACTION BEGIN instruction and a TRANSACTION END instruction are provided. The TRANSACTION BEGIN instruction causes either a constrained or nonconstrained transaction to be initiated, depending on a field of the instruction. A constrained transaction has one or more restrictions associated therewith, while a nonconstrained transaction is not limited in the manner of a constrained transaction. The TRANSACTION END instruction ends the transaction started by the TRANSACTION BEGIN instruction.

Abstract: A Load/Store Disjoint instruction, when executed by a CPU, accesses operands from two disjoint memory locations and sets condition code indicators to indicate whether or not the two operands appeared to be accessed atomically by means of block-concurrent interlocked fetch with no intervening stores to the operands from other CPUs. In a Load Pair Disjoint form of the instruction, the accesses are loads and the disjoint data is stored in general registers.

Abstract: One embodiment is a computer-implemented method for safe conditional operation when storage access cannot be proven safe. The method includes receiving a portion of source code for a transaction by an enhanced compiler and. The portion of source code received is analyzed, by the enhanced compiler, to determine whether the portion of source code is a candidate for transformation. Responsive to a determination that the portion of source code analyzed by the enhanced compiler is a candidate for transformation, the portion of the source code analyzed is transformed, by a computer processor, to use a conditional operation in a first portion of the transformed code. The conditional operation uses hardware transaction memory to invoke retry operations within hardware. A branch is added, directed to an original code portion, in a second portion of transformed code, where the branch is a recovery portion containing the original code portion.

Abstract: Machine instructions, referred to herein as a long Convert from Zoned instruction (CDZT) and extended Convert from Zoned instruction (CXZT), are provided that read EBCDIC or ASCII data from memory, convert it to the appropriate decimal floating point format, and write it to a target floating point register or floating point register pair. Further, machine instructions, referred to herein as a long Convert to Zoned instruction (CZDT) and extended Convert to Zoned instruction (CZXT), are provided that convert a decimal floating point (DFP) operand in a source floating point register or floating point register pair to EBCDIC or ASCII data and store it to a target memory location.

Abstract: Machine instructions, referred to herein as a long Convert from Zoned instruction (CDZT) and extended Convert from Zoned instruction (CXZT), are provided that read EBCDIC or ASCII data from memory, convert it to the appropriate decimal floating point format, and write it to a target floating point register or floating point register pair. Further, machine instructions, referred to herein as a long Convert to Zoned instruction (CZDT) and extended Convert to Zoned instruction (CZXT), are provided that convert a decimal floating point (DFP) operand in a source floating point register or floating point register pair to EBCDIC or ASCII data and store it to a target memory location.

Abstract: A selected group of Guest machine instructions in an emulation environment are translated to a semantic routine of Host machine instructions, wherein Guest cells corresponding to an opcode portion of a Guest instruction are mapped to corresponding Host cells, wherein the semantic routine of Host machine instructions are patched into a Host cell corresponding to the first Guest cell of the group of Guest machine instructions, wherein other Host cells of the corresponding Host cells are patched with semantic routines for emulating single instructions associated with the corresponding Guest cell.