Re: [Caml-list] Another great advantage for OCaml language due to Markus Mottl

["Mike Lin" <mikelin@mit.edu>]

Now that it exists, I strongly second incorporating it (as a compiler
switch) into the official release. ASAP. IMHO untraceable exceptions
have been one of the worst things about native code OCaml for a very
long time.

On 3/21/06, Andries Hekstra <andries.hekstra@philips.com> wrote:
>
> Dear Member of the OCaml mailing list,
>
> The problem about which I reported on this reflector around two weeks ago
> (array index violation after around 4 days) has in the mean time been solved
> thanks to the great native function call backtrace for the ocamlopt compiler
> due to Markus Mottl. Given that my program crashed after 3.7 days, and my
> program ran around 30x slower in byte code, debugging using byte code was
> not an option (this slowdown had been similar if I had used _DEBUG mode of a
> C++ program instead of _RELEASE version). Also, as reported earlier, putting
> "try ... with " around all attempts to index an array is not feasbile in
> standard OCaml for array elements in the left hand sides of assignments. A
> static unhandled exception checker provided on a web page, ran into dead
> HTML links.
>
> Hence, the native function call, which comes at minimal runtime overhead
> cost, mainly the cost of -inline 0, is a great new feature that would give
> OCaml another advantage over C++ when added to the OCaml language in a next
> release. Below I give a toy example :
>
> --- nlv13512/TestProgram ---> ls
> attempt.ml*
> --- nlv13512/TestProgram ---> cat att*
> let a = Array.make 2 0;;
> let f i = i*i;;
> let g i = a.(i);;
> let b = f 2;;
> let c = g 2;;
> --- nlv13512/TestProgram ---> ocamlopt -inline 0 -gb attempt.ml
> --- nlv13512/TestProgram ---> a.out
> Fatal error: exception Invalid_argument("index out of bounds")
> Native function backtrace:
>
>   camlAttempt__g_60
>   camlAttempt__f_58
> --- nlv13512/TestProgram --->
>
> =Andries
>
> PS The attached patch was provided to me by Markus Mottl for the 3.09.1.
> release.
>
>
>
>
> ------------------------------------------------------------------------
>  Dr. Ir. Andries P. Hekstra
>  Philips Research
>  High Tech Campus 27  (WL-1-4.15)
>  5656 AG Eindhoven
>  Tel./Fax/Secr. +31 40 27 42048/42566/44051
>    *  Good open source anti-RSI software : http://www.workrave.org
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