A circuit is provided which includes arithmetic computation logic configured to add or subtract operands of variable length to produce a result in a sign-magnitude data format. The circuit also includes an overflow detector to provide an overflow signal indicative of whether the result fits within a specified result length l. The overflow detector operates on the operands prior to the arithmetic computation logic producing the result to determine, independent of the result produced by the arithmetic computation logic, whether the result fits within the specified result length l.

Setting or updating of floating point controls is managed. Floating point controls include controls used for floating point operations, such as rounding mode and/or other controls. Further, floating point controls include status associated with floating point operations, such as floating point exceptions and/or others. The management of the floating point controls includes efficiently updating the controls, while reducing costs associated therewith.

Setting or updating of floating point controls is managed. Floating point controls include controls used for floating point operations, such as rounding mode and/or other controls. Further, floating point controls include status associated with floating point operations, such as floating point exceptions and/or others. The management of the floating point controls includes efficiently updating the controls, while reducing costs associated therewith.

Execution of a machine instruction in a central processing unit. A perform floating-point operation instruction and a test bit are obtained. If the test bit has a first value, a specified floating-point operation function is performed, and a condition code is set to a value determined by the specified function. If the test bit has a second value, a check is made to determine if the specified function is valid and installed on the machine. If the specified function is valid and installed on the machine, the condition code is set to one code value, and if the specified function is either not valid or not installed on the machine, the condition code is set to a second code value.

A processor includes a front end to decode an instruction and an allocator to assign the instruction to an execution unit to execute the instruction to compute a floating point result subject to a cancellation effect. The execution unit includes a threshold to control notification the cancellation effect, a logic to compute the maximum exponent from a source value, a logic to compute the floating point exponent, a logic to compute the detected cancellation value, and a logic to compare the detected cancellation value to the threshold.

A circuit is provided which includes arithmetic computation logic configured to add or subtract operands of variable length to produce a result in a sign-magnitude data format. The circuit also includes an overflow detector to provide an overflow signal indicative of whether the result fits within a specified result length l. The overflow detector operates on the operands prior to the arithmetic computation logic producing the result to determine, independent of the result produced by the arithmetic computation logic, whether the result fits within the specified result length l.

A circuit is provided which includes arithmetic computation logic configured to add or subtract operands of variable length to produce a result in a sign-magnitude data format. The circuit also includes an overflow detector to provide an overflow signal indicative of whether the result fits within a specified result length l. The overflow detector operates on the operands prior to the arithmetic computation logic producing the result to determine, independent of the result produced by the arithmetic computation logic, whether the result fits within the specified result length l.

A method and system are disclosed for executing a machine instruction in a central processing unit. The method comprises the steps of obtaining a perform floating-point operation instruction; obtaining a test bit; and determining a value of the test bit. If the test bit has a first value, (a) a specified floating-point operation function is performed, and (b) a condition code is set to a value determined by said specified function. If the test bit has a second value, (c) a check is made to determine if said specified function is valid and installed on the machine, (d) if said specified function is valid and installed on the machine, the condition code is set to one code value, and (e) if said specified function is either not valid or not installed on the machine, the condition code is set to a second code value.

Embodiments of the present disclosure include a tininess prediction and handler engine for handling numeric underflow while streamlining the data path for handling normal range cases, thereby avoiding flushes, and reducing the complexity of a scheduler with respect to how dependent operations are handled. A preemptive tiny detection logic section can detect a potential tiny result for the function or operation that is being performed, and can produce a pessimistic tiny indicator. The tininess prediction and handler engine can further include a subnormal post-processing pipe, which can denormalize and round one or more subnormal operations while in a post-processing mode. A schedule modification logic section can reschedule in-flight operations. The schedule modification logic section can issue dependent operations optimistically assuming that a producing operation will not produce a tiny result, and so will not incur extra latency associated with fixing the tiny result in the post-processing pipe.

Processing within a computing environment is facilitated. An operand of an instruction is obtained, which includes decimal floating point data encoded in a compressed format. An operation is performed on the operand absent decompressing a source value of a trailing significand of the decimal floating point data in the compressed format.