[Zlib-devel] TR: result of compression test

[Cosmin Truta]

On Mon, Jul 26, 2010 at 1:22 PM, Gilles Vollant wrote:
> If possible, I'm curious of other people on this list test and compare all
> the dll
> both for compatibility (which must be perfect) and performance
> the VS2010 DLL seem faster

You mean, test the VC++ build to make sure it's compatible with the
MinGW build, and not the other way around, yes?

I'm not being sarcastic here. Since VC7, up until the present-day
version, Microsoft constantly broke the binary compatibility, by
supplying a slightly different, slightly incompatible C runtime, every
time. On the other hand, MinGW has been in the business of supplying
VC6-compatible, MSVCRT-compatible builds, and that project is still
going on, quite well. I expect the MinGW build to be compatible with
the old ZLIB1.DLL, more than I expect the same from the VC build.

The good news, as pointed out by John Bowler in an old message on this
list, is that C run-time intermixing might work in zlib, because files
are opened and closed outside zlib, and the memory allocated by zlib
is also freed by zlib. So we might be lucky, and be able to remove the
restriction to link to MSVCRT.DLL.

This benefit will go away when zlib will no longer feature this design.

I would like to see us getting rid of the MSVCRT.DLL dependency at one
point in the future. It's good to at least have the choice between the
latest and greatest MinGW, versus the latest and greatest VC++. As
Gilles points out, today's VC++ ASM build is slightly faster than
today's MinGW ASM build. And what about the DLL for Win64?
But that has to be analyzed carefully, and the specification (i.e.
DLL_FAQ) must be updated accordingly. I can't include the VC++ build
right now, because it's neither built according to the specification,
nor is it sure to be fully backwards compatible to the old ZLIB1.DLL.
We obviously can't update the DLL_FAQ that was published with 1.2.5.

IMO, getting rid of the MSVCRT dependency is something that's worth
discussing (and testing) for 1.2.6.

Best regards,
Cosmin