Digital Equipment Corporation

William B Noyce

Kevin W Harris

Simon C Steely, Jr

David J Sager

Steven O Hobbs

Daniel L Murphy

Curt K Burmeister

A jacketing system automatically interfaces dissimilar program units during program execution on a computer system. Means are provided for detecting a call for execution of a second program unit having a second call standard form a first program unit having a first call standard during execution of the first program unit on the computer system. A procedure descriptor is used in the code for the first program unit and it includes a signature that defines the call standard for each incoming call to the first program unit. A bound procedure descriptor is also used in the code for each outgoing call from the first program unit and it includes a signature that defines the call standard for the target program unit. Jacketing routines are driven by the descriptors in jacketing calls between the two program units.

System and method for automatically interfacing call conventions between

A pipelined processor includes an instruction box including a register mapper, to map register operand fields of a set of instructions and an instruction scheduler, fed by said set of instructions, to reorder the issuance of said set of instructions from said instruction processor. The mapped register operand fields are associated with the corresponding instructions of said reordered set of instructions prior to issuance of the instructions. The processor further includes a branch prediction table which maps a stored pattern of past histories associated with a branch instruction to a more likely prediction direction of the branch instruction. The processor further includes a memory reference tagging store associated with the instruction scheduler so that the scheduler can reorder memory reference instructions without knowing the actual memory location addressed by the memory reference instruction.

Past-history filtered branch prediction

A system and method for controlling execution of nested loops in parallel in a computer including multiple processors, and a compiler for generating code therefor. The code enables the computer to operate in the following manner. Each processor processes an iteration of an outer loop in a set of nested loops. If the outer loop contains more iterations than processors in the system, the processors are initially assigned early iterations, and the later iterations are assigned to the processors as they finish their earlier iterations, until the processors have processed all of the iterations. Each processor, during processing of an outer loop iteration runs the iterations comprising the inner loop serially. In order to enforce dependencies between the loops, each processor reports its progress in its iterations of the inner loop to the processor executing the succeeding outer loop iteration. In addition, each processor, before processing the inner loop iterations of an assigned outer loop iteration, determines whether the processor computing the preceding outer loop is ahead or behind in processing its inner loop iteration by an amount which guarantees that dependencies will be enforced.

System and method for controlling execution of nested loops in parallel

A compiler includes a register allocation method making use of the concept of assigning temporary items to lifetime holes if such holes exist that are suitable. The compiler includes a front end for converting the input code to an intermediate representation, then this input representation is traversed to identify all of the temporary items, and to find all of the holes in the temporary items. Lists are maintained of the identified temporaries and holes. Register allocation then includes assigning temporaries to registers so long as there are free registers, and if holes are available in already-assigned temporaries then these holes are used in assigning registers. After all the available registers and holes are used, remaining temporaries are unallocated and thus represent memory references.

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Hollis, NH, United States of America

William B Noyce