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From: Tom H. <th...@cy...> - 2004-08-26 09:19:43
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In message <Pin...@he...>
Nicholas Nethercote <nj...@ca...> wrote:
> On Thu, 26 Aug 2004, Tom Hughes wrote:
>
>>> Hmm? I would have expected that the simulated environment created by
>>> Valgrind (CPU and parts of Linux/libc) behaves the same as the environment
>>> being simulated. Any deviation may (and hence one day will) make the
>>> program being tested behave differently when run with or without Valgrind,
>>> reducing its effectiveness.
>>
>> The problem is that there is not a one-one (or even a one-many) mapping
>> from instructions in the original program to JITed instructions
>
> Hmm, that's not really true; there is a one-many mapping from
> original-->JITted instructions. The INCEIP UCode instruction marks
> the boundaries.
You are quite right of course. I thought there was some mingling
at the boundaries when we translated back from UCode to x86 but
presumably if there is it doesn't across an INCEIP instruction.
Tom
--
Tom Hughes (th...@cy...)
Software Engineer, Cyberscience Corporation
http://www.cyberscience.com/
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