International Business Machines Corporation

Liangxiao Hu

Yaoqing Gao

Raul Esteban Silvera

Geoffrey Owen Blandy

Roch Georges Archambault

Ettore Tiotto

James Lawrence McInnes

Guansong Zhang

Peng Zhao

Roland Froese

A compiler method for exploiting data value locality for computation reuse. When a code region having single entry and exit points and in which a potential computation reuse opportunity exists is identified during runtime, a helper thread is created separate from the master thread. One of the helper thread and master thread performs a computation specified in the code region, and the other of the helper thread and master thread looks up a value of the computation previously executed and stored in a lookup table. If the value of the computation previously executed is located in the lookup table, the other thread retrieves the value from the table, and ignores the computation performed by the thread. If the value of the computation is not located, the other thread obtains a result of the computation performed by the thread and stores the result in the lookup table for future computation reuse.

Compiler method of exploiting data value locality for computation reuse

Control flow information and data flow information associated with a program containing a upc_forall loop are built. A shared reference map data structure using the control flow information and the data flow information is created. All local shared accesses are hashed to facilitate a constant access stride after being rewritten. All local shared references in a hash entry having a longest list are privatized. The upc_forall loop is rewritten into a for loop. Responsive to a determination that an unprocessed upc_forall loop does not exist, dead store elimination is run. The control flow information and the data flow information associated with the program containing the for loop is rebuilt.

Unified parallel C work-sharing loop construct transformation

Systems, methods and computer products for compiler support for aggressive safe load speculation. Exemplary embodiments include a method for aggressive safe load speculation for a compiler in a computer system, the method including building a control flow graph, identifying both countable and non-countable loops, gathering a set of candidate loops for load speculation, and for each candidate loop in the set of candidate loops gathered for load speculation, computing an estimate of the iteration count, delay cycles, and code size, performing a profitability analysis and determining an unroll factor based on the delay cycles and the code size, transforming the loop by generating a prologue loop to achieve data alignment and an unrolled main loop with loop directives, indicating which loads can safely be executed speculatively and performing low-level instruction scheduling on the generated unrolled main loop.

Systems, methods, and computer products for compiler support for aggressive safe load speculation

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Liangxiao Hu