BIB-VERSION:: CS-TR-v2.0
          ID:: STAN//CSL-TR-97-715
       ENTRY:: September 30, 1997
ORGANIZATION:: Stanford University, Computer Systems Laboratory
       TITLE:: Software and Hardware for Exploiting Speculative Parallelism
               with a Multiprocessor
        TYPE:: Technical Report
      AUTHOR:: Oplinger, Jeffrey
      AUTHOR:: Heine, David
      AUTHOR:: Liao, Shih-Wei
      AUTHOR:: Nayfeh, Basem A.
      AUTHOR:: Lam, Monica S.
      AUTHOR:: Olukotun, Kunle
        DATE:: february 1997
       PAGES:: 26
    ABSTRACT:: Thread-level speculation (TLS) makes it possible to
               parallelize general purpose C programs. This paper proposes
               software and hardware mechanisms that support speculative
               thread- level execution on a single-chip multiprocessor. A
               detailed analysis of programs using the TLS execution model
               shows a bound on the performance of a TLS machine that is
               promising. In particular, TLS makes it feasible to find
               speculative do across parallelism in outer loops that can
               greatly improve the performance of general-purpose
               applications. Exploiting speculative thread-level parallelism
               on a multiprocessor requires the compiler to determine where
               to speculate, and to generate SPMD (single program multiple
               data) code.We have developed a fully automatic compiler
               system that uses profile information to determine the best
               loops to execute speculatively, and to generate the
               synchronization code that improves the performance of
               speculative execution. The hardware mechanisms required to
               support speculation are simple extensions to the cache
               hierarchy of a single chip multiprocessor. We show that with
               our proposed mechanisms, thread-level speculation provides
               significant performance benefits.
       NOTES:: [Adminitrivia V1/Prg/19970930]
         END:: STAN//CSL-TR-97-715