TITLE: REP STRING IDENTIFICATION

ISSUE_NAME:  REP_STRING

DESCRIPTION:

REP strings are the common name given to instructions that contain the rep prefix.  The most typical usage is a “rep mov” to inline a memcpy or a “rep sto” in inline a memset.
RELEVANCE:

REP strings are relevant for all architectures on all OS’s.  REP strings are often the most efficient way to accomplish a memcpy or memset operation.  The Atom architecture on cores codenamed Bonnell, Silverthorne or Saltwell are an exception where there are usually more efficient ways to accomplish a memcpy or memset.

EXAMPLE:

SOLUTION:

On Atom architecture (codenamed Bonnell, Silverthorne or Saltwell), the best methodology is to utilize a more efficient implementation for memcpy/memset.  The Intel compiler comes with optimized implementations and the libraries used in glibc 2.12.1 (and on) are optimized.

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