Re: double val to long val conversion issue

On 09/02/13 15:47, Pierre Joye wrote:

hi Remi On Sat, Feb 9, 2013 at 4:10 PM, Remi Collet <remi@fedoraproject.org> wrote:

About http://git.php.net/?p=php-src.git;a=commitdiff;h=79956330fe17cfd5f60de456497541b21a89bddf (For now, I have reverted this fix) Here some explanations. LONG_MAX is 9223372036854775807 (0x7fffffffffffffff) double representation of LONG_MAX is 9223372036854775808 (d > LONG_MAX) is evaluated in double space. So is false for double which have the same value than (double)LONG_MAX. So, for (double)LONG_MAX the cast used is

         (long)d

9223372036854775807 on ppc64 9223372036854775808 on x86_64 (gcc without optimization) 9223372036854775807 on x86_64 (gcc -O2) PHP expected value is 9223372036854775808 (Btw, I don't understand why PHP, build on x86_64, with -O2, gives the good result, some environment mystery) Obviously, we could have different result on different platform, compiler, architecture. I will be very interested by result on other platform (mac, windows), compiler (Visual C), architecture. If we switch to the unsigned cast:

         (long)(unsigned long)d;

Any comments ?

IIRC, on windows/visualC, no matter if it is x86 or x64, long is always 32bits, so it won't change the size of long. See http://en.wikipedia.org/wiki/LLP64#64-bit_data_models for a good description of this mess. AFAIK many packages that target both 32 and 64 bit environments MS and *nix, define explicitly adopt XXX_int32, XXX_uint32, XXX_int64, XXX_uint64, ... datatypes and use wrappers to map these onto the appropriate visualC / gcc types. As far as I can see, PHP doesn't and seems to use long and int almost interchangeably which causes problems as LP64/I32LP64 and LLP64/IL32P64 are very different. This is one reason for 64-bit support on Windows being problematic.

It would be good for PHP to have a road map to removed data model-specific potholes, say by 5.6 or 5.7. //Terry