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To: "'Stanislav Malyshev'" <smalyshev@gmail.com>,
	"'Zeev Suraski'" <zeev@zend.com>
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Date: Sun, 22 Feb 2015 23:28:13 +0100
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Subject: RE: [PHP-DEV] Coercive Scalar Type Hints RFC
From: francois@php.net (=?utf-8?Q?Fran=C3=A7ois_Laupretre?=)

Hi Stas,

It seems the actual problem is that we have too many compiler / code =
analysis experts in the community ;)

(don't get me wrong, I am not saying that for you, I just admire your =
patience explaining the same again and again to people who never read =
one line from PHP core source).

Regards

Fran=C3=A7ois

> -----Message d'origine-----
> De : Stanislav Malyshev [mailto:smalyshev@gmail.com]
> Envoy=C3=A9 : dimanche 22 f=C3=A9vrier 2015 21:39
> =C3=80 : Jefferson Gonzalez; Etienne Kneuss; Anthony Ferrara; Zeev =
Suraski
> Cc : PHP internals
> Objet : Re: [PHP-DEV] Coercive Scalar Type Hints RFC
>=20
> Hi!
>=20
> > A JIT or AOT machine code generator IMHO will never have a decent =
use of
> > system resources without some sort of strong/strict typed rules,
> > somebody explain if thats not the case.
>=20
> Yes, that's not the case, at least nobody ever showed that to be the
> case. In general, as JS example (among many others) shows, it is
> completely possible to have JIT without strict typing. In particular,
> coercive typing provides as much information as strict typing about
> variable type after passing the function boundary - the only =
difference
> is what happens _at_ the boundary and how the engine behaves when the
> types do not match, but I do not see where big performance difference
> would come from - the only possibility for different behavior would be
> if your app requires constant type juggling (checks are needed in =
strict
> mode anyway, since variables are not typed) - but in this case in =
strict
> mode you'd have to do manual type conversions, which aren't in any way
> faster than engine type conversions.
> So the case for JIT being somehow better with strict typing so far
> remains a myth without any substantiation.
>=20
> > while on strict mode the generated code could be:
> >
> > int calc(int val1, int val2) {
> >     return val1 + val2;
> > }
>=20
> No, it can't be (at least it can't be the _entire_ code of this
> function), since the user still can pass non-int into this function -
> nothing introducing strict typing in functions, as it is proposed now,
> prevents it. What strict typing does is to ensure the error in this
> case, but to generate the error you still need the checks!
> BTW, your weak mode code is wrong too - there's no need to generate
> Variants if you typed the variables as int. You know once coercion is
> done they are ints. At least in the model that was now proposed.
>=20
> > If my example is right it means strict would be better to achieve =
good
>=20
> Unfortunately, your example is not right.
>=20
> > to another level of integration with PHP and performance. IMHO is =
harder
> > and more resource hungry to implement a JIT/AOT using weak mode. =
With
>=20
> Please provide a substantiation for this opinion. So far what was
> provided was not correct.
>=20
> > Thats all that comes to mind now, and while many people doesn't care =
for
> > performance, IMHO a programming language mainly targeted for the web
> > should have some caring on this department.
>=20
> Please do not strawman. A lot of people here care about performance, =
and
> you have not yet made case that strict typing has any benefit on
> performance, so implying that opponents of strict typing somehow don't
> care about performance while you champion it does not match the real
> situation.
> --
> Stas Malyshev
> smalyshev@gmail.com
>=20
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