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Re: Compile option to disable taint mode: speedup

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From:
Steffen Mueller
Date:
October 9, 2012 22:28
Subject:
Re: Compile option to disable taint mode: speedup
Message ID:
50750771.6090302@cpan.org
On 10/10/2012 12:04 AM, Greg Lindahl wrote:
> On Tue, Oct 09, 2012 at 11:29:45PM +0200, Leon Timmermans wrote:
>> On Tue, Oct 9, 2012 at 10:42 PM, Vincent Pit <perl@profvince.com> wrote:
>>> Note that disabling taint mode would make it very difficult to install many
>>> modules from the CPAN, as a lot of tests are run in taint mode (it was
>>> considered "good practice" some time ago).
>>
>> You could conditionally ignore that on a TAP::Harness level.
>
> If we're going to say that disabling taint works, someone should
> figure out a way to smoke it, and then smoke every release with taint
> disabled. Friends don't encourage friends to use unsmoked features!
>
> This is the cost of turning this from an experiment into something
> people will regularly use.
>
> We'd be willing to help out, but I'm not sure if we're up to smoking
> CPAN on a regular basis.

This "CPAN modules use it in tests" business is the main reason why for 
work, I'd probably build it to ignore -t/-T. It's just that I'd rather 
not be on public record saying that *others* should do the same. :)

On a side note, the 10% figure was on a particular micro-benchmark. 
Nicholas ran mktables as a benchmark on his Mac using the 
avoid-alignment-noise options. He found an improvement of about 1%. 
Callgrind on my machine seems to agree about losing roughly 1-2% of 
instructions.

Big question is what -t/-T should do by default. Maybe have two 
Configure options. NO_TAINT_SUPPORT (exception on -t/-T) and 
SILENT_NO_TAINT_SUPPORT (ignore -t/-T).

Still, some tests would fail if they explicitly test taint mode. Making 
those pass would require exposing "do I have taint mode" to perl.

If you want to help out, there's an explicit list of things that need 
addressing in my email to the list and in the commit message. I'll hack 
on it some more now.

Best regards,
Steffen

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