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Re^6: perllVm: A start.

by BrowserUk (Pope)
on Sep 05, 2012 at 13:42 UTC ( #991856=note: print w/ replies, xml ) Need Help??


in reply to Re^5: perllVm: A start.
in thread perllVm: A start.

For whom, mister anonymous?

A simple example. A bug (exception fault) that arises from the interaction of LLVM, MSVC and a 40,000-line post preprocessed C-source. Compile the source to bitcode, feed it to one of their tools and it does a binary chop on the code, excluding bits of it -- in a code-aware manner -- until the trap doesn't occur. Put the bit back that contains the bug and remove other bits. Rinse and repeat until you've excluded everything that doesn't contribute to the trap.

In less than 2 minutes, it reduces 40,000 lines of C, to 680 bytes of bitcode, that converted back amounts to about 12 lines of C. A simple, standalone testcase for further examination.


With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

RIP Neil Armstrong


Comment on Re^6: perllVm: A start.
Re^7: perllVm: A start.
by Will_the_Chill (Pilgrim) on Sep 05, 2012 at 20:58 UTC
    That's pretty awesome. I've wanted something like that for Inline::C code for a while.
Re^7: perllVm: A start.
by Anonymous Monk on Sep 05, 2012 at 21:16 UTC

    For whom, mister anonymous?

    For all the world :) I figured that asking for a proper how-to use one of those tools, was asking a bit much to ask

    But a peek at peek at your screen as you're doing what you do?

    Might be a nice demonstration, inspire other to try it...

    :)

      I have neither the means nor inclination to produce a video, but see http://llvm.org/docs/Bugpoint.html


      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.

      RIP Neil Armstrong

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