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SUMMARY:Optimizing Dynamically Updateable Programs - Boris Feigin (Univers
 ity of Cambridge)
DTSTART:20090605T141500Z
DTEND:20090605T151500Z
UID:TALK18768@talks.cam.ac.uk
CONTACT:Boris Feigin
DESCRIPTION:A dynamic software update is an update to program code that is
  applied at runtime.  While the mechanics of altering the image of a runni
 ng program are straightforward\, at least on a von Neumann machine\, _what
 _ constitutes a valid update and when it may be applied is up for debate. 
  At the same time\, anecdotal evidence suggests that dynamic updates coexi
 st poorly with program optimization.  This is hardly surprising---a dynami
 c update makes implicit assumptions about the intermediate state of the pr
 ogram at the time it is applied\, which in turn limit the compiler's scope
  for optimization.  The greater the dependence of an update on the origina
 l program\, the more disruptive it is.  I will describe an approach to opt
 imizing dynamically updateable programs that involves restricting the kind
 s of updates that may be applied at each update point.  Restrictions that 
 are too onerous can be relaxed with dynamic deoptimization\, a technique d
 ue to Hölzle et al. for source-level debugging of optimized programs.  Th
 is will be a half-hour talk.
LOCATION:GS15\, Computer Laboratory
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