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DTSTART:19700927T020000
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CATEGORIES:ECS Seminars
CONTACT:Stephen Kell (King's College London)
DESCRIPTION:Source-level debugging of compiled code only works when compile
 rs generate the necessary metadata. Currently\, that means it rarely works
  well\, at least in optimising ahead-of-time compilers like LLVM and GCC. 
 I'll give an overview of how compiler-generated metadata enables source-le
 vel debugging\, the challenges of making it work for optimised code\, and 
 our recent work on doing better. Whereas compilers have so far taken a "be
 st-effort" approach\nwith no particular correctness criterion\, I'll outli
 ne a correctness condition for local variable information that seems to ba
 lance the relevant trade-offs. I'll then describe a tool we've built that 
 can use this to mechanically find valid LLVM bugs capturing avoidable loss
 es or corruptions\nof debug info. A theme will be how the textbook framing
  of compiler optimisations as "eliminating" code or variables could be mor
 e constructively thought of as "residualising" them into debug info\; I'll
  finish with some thoughts on what that could mean for how compilers are b
 uilt. All this is joint work with J. Ryan Stinnett.\n\nBio: Stephen Kell d
 oes practical research on programming systems\, with the the goal of makin
 g computers work for human beings and not vice-versa\, and a focus on infr
 astructure software including operating systems and language runtimes. Som
 e past and present research topics include: realistic formal and metaprogr
 ammable specifications of operating systems' linking\, loading and system 
 call interfaces\; reflective run-time services in Unix-like processes\; us
 ing the latter to provide new kinds of dynamic checking in C and other 'un
 safe' languages\; and making debugging of optimized code more \nreliable. 
 Currently he is a Lecturer (Assistant Professor) in Computer Science at Ki
 ng's College London.\nhttps://www.kcl.ac.uk/people/stephen-kell\n\nZoom: h
 ttps://vuw.zoom.us/my/spgroom
DTEND;TZID=Pacific/Auckland:20231113T120000
DTSTAMP:20260502T085116Z
DTSTART;TZID=Pacific/Auckland:20231113T110000
LOCATION:Meeting Room\, MARU 101
ORGANIZER:Stephen Kell (King's College London)
SUMMARY:Stephen Kell (King's College London) - How debuggable is your (comp
 iler-optimised) program?
UID:seminar_ecs1374_20231110132317
URL:https://www.humprog.org/~stephen/
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