On Friday, 31 October 2014 at 11:42:05 UTC, Steven Schveighoffer
wrote:
On 10/31/14 4:40 AM, "Marc =?UTF-8?B?U2Now7x0eiI=?=
<[email protected]>" wrote:
On Thursday, 30 October 2014 at 20:15:36 UTC, Steven
Schveighoffer wrote:
I think the above result is deceptive, and the test isn't
very useful.
The RuntimeString toString isn't a very interesting data
point -- it's
simply a single string. Not many cases are like that. Most
types have
multiple members, and it's the need to *construct* a string
from that
data which is usually the issue.
But I would caution, the whole point of my query was about
data on the
platforms of which Manu speaks. That is, platforms that have
issues
dealing with virtual calls. x86 doesn't seem to be one of
them.
OTOH, ArrayOfStrings shows that allocating is worse by several
orders of
magnitudes. This will not change on any architecture. And the
simple
sink variant is still faster than the rest by almost an order
of
magnitude, this may also be unlikely to be much different on
these
architectures.
I find it hard to believe that the delegate version is going to
be slower than the memory version on any architecture also. But
I must defer to Manu as the expert in those architectures. This
is why I asked for a test. The presented data is useful, but
not for the purpose of my query. I need to know if it performs
bad on these platforms, not how it performs on x86. We should
be willing to entertain other proposals for how toString should
work, but not if it's proven that what we have will suffice.
It should be possible to perform such a test without D support.
In any case, I think there is still room for improvement inside
the implementations of toString as has been mentioned.
-Steve
I wrote a Windows CE app to run on our printers here at HP to
test what the Microsoft ARM compiler does with virtual function
calls. I had to do an operation with a global volatile variable
to prevent the compiler from inlining the non-virtual function
call but I finally got it to work.
Calling the function 100 million times yielded the following
times:
Windows Compiler on ARM (Release)
-------------------------------------------
NonVirtual: 0.537000 seconds
Virtual : 1.281000 seconds
Windows Compiler on x86 (Release)
-------------------------------------------
NonVirtual: 0.226000 seconds
Virtual : 0.226000 seconds
Windows Compiler on x86 (Debug)
-------------------------------------------
NonVirtual: 2.940000 seconds
Virtual : 3.204000 seconds
Here's the link to the code:
http://marler.info/virtualtest.c
