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D - [BUG] dmd segfaults on sdl_syswm.d

reply "Christian Schüler" <leichenzehrer alpenjodel.de> writes:
Hi Walter,

Using the SDL version currently available from the DedicateD page, and DMD
version 0.79, I get a segfault. The module which causes trouble is
sdl_syswm.d. If I comment out this module from beeing imported, no crash
happens. An empty application importing sdl.d is sufficient to reproduce the
bug. More specifically:

import sdl.d --> import sdl_events.d --> import sys_syswm.d --> crash


PS:
Thumbs up for the continuing improvements on D! Templates and operator
overloading hasn't been there the last time I checked D, which must have
been early 2002.

I also tried to write a litte vector3-struct with the new operator
overloading and checked the asm-output of the compiler (it's kind of a thing
I try with every new compiler I get my hands on).

Result 1:
I found out that the current D compiler doens't care much about the -O
switch and inlining option. This is ok, it's not an 1.0 version after all.

Result 2:
I was surprised to see the "movsd" instruction is used to copy values
around. I'm surprised because it's said to be deprecated and this is
probably a general code-generation feature of your backend and not releated
to D alone. Example:


struct vector3
{
   float x, y, z;
   vector3 opPlus( const vector3 &other )
   { vector3 result; result.x = x + other.x; .... ; return result; }
}

vector3 A, B, C;
A = B + C;

The asm of opPlus() with -O is structured like this, correct me if I'm wrong

   prolog
   mov edi, & result
   mov esi, & (default-initializer object ?)
   movsd
   movsd
   movsd
   floating point oprations
   mov edi, &A
   mov esi, &result
   movsd
   movsd
   movsd
   epilog
   ret

Besides there beeing a redundant copy and the whole function not beeing
inlined, the asm makes use of the string instruction "movsd". It is believed
that string instructions and other complex instructions (bit-scans for
instance) don't translate well to modern processor's microcode and are
deprecated in favor of writing more risc-like code. So you should do
instead:

   mov edi, &A
   mov esi, &result
   mov eax, dword ptr [esi]
   mov dword ptr [edi], eax
   mov eax, dword ptr [esi+8]
   mov dword ptr [edi+8], eax
   mov eax, dword ptr [esi+16]
   mov dword ptr [edi+16], eax

Is anybody able to confirm this? (For the record, GCC does produce risc-like
output)

Greetings
Christian
Jan 25 2004
next sibling parent yaneurao <yaneurao_member pathlink.com> writes:
prev sibling  parent reply "Walter" <walter digitalmars.com>  writes:


  parent reply "Christian Schüler" <leichenzehrer alpenjodel.de>  writes:


Hi Walter,
here you are (see attachment)

----------------------------------

import sdl_syswm;

int main()
{
    return 0;
}

----------------------------------

- importing sdl_version doesn't crash
- replicating the code of sdl_syswm into the main file doesn't crash
- renaming sdl_version to sdl_ver doesn't crash

hope this helps



"Walter" <walter digitalmars.com> schrieb im Newsbeitrag
news:bv3n4g$1g6v$1 digitaldaemon.com...


 Can you please cut it down to a minimum example and post it / email it to
 me? Thanks.




begin 666 SDL_syswm.zip

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end



 Jan 27 2004



  parent reply ahiru <ahiru moephp.org>  writes:


  parent reply "Christian Schüler" <leichenzehrer alpenjodel.de>  writes:


Is this going to be fixed in the future?
Or must we assume that struct names equalling module names are not going to
be accepted by the compiler?


"ahiru" <ahiru moephp.org> schrieb im Newsbeitrag
news:bv699a$2nk9$1 digitaldaemon.com...

  parent reply "C" <dont respond.com>  writes:


I never understood why that was , it seems naturall to me to write module
myClass; \n\n class myClass { } ... .  Could we get this ?

C

 next sibling parent  yaneurao <yaneurao_member pathlink.com>  writes:


In article <bv9343$1ch1$1 digitaldaemon.com>, C says...

I never understood why that was , it seems naturall to me to write module
myClass; \n\n class myClass { } ... .  Could we get this ?


of course , you are right.

this may be a bug ,
a pity it doesn't occur in Mr.Walter's environment.

cf.
http://www.digitalmars.com/drn-bin/wwwnews?D/21886

yaneurao.



 Jan 28 2004



prev sibling  parent reply J C Calvarese <jcc7 cox.net>  writes:


C wrote:

 I never understood why that was , it seems naturall to me to write module
 myClass; \n\n class myClass { } ... .  Could we get this ? 


I haven't been following this thread particularly closely, but I think 
we can do this.  Both of the examples I attached work for me.

Does it fail when the example is more complicated (such was with 
importing)?  This sounds like it might be a bug.


-- 
Justin
http://jcc_7.tripod.com/d/



 Jan 28 2004



  parent reply "Christian Schüler" <leichenzehrer alpenjodel.de>  writes:


Hi JC
As I pointed out, the crashed only if the offending instruction was "2
modules deep".

import sdl --> import sdl_syswm --> implort sdl_version

if instead

import sdl_version

no crash happened

-chris


"J C Calvarese" <jcc7 cox.net> schrieb im Newsbeitrag
news:bv9jac$28qb$1 digitaldaemon.com...

 C wrote:

 I never understood why that was , it seems naturall to me to write




module

 myClass; \n\n class myClass { } ... .  Could we get this ?


 I haven't been following this thread particularly closely, but I think
 we can do this.  Both of the examples I attached work for me.

 Does it fail when the example is more complicated (such was with
 importing)?  This sounds like it might be a bug.


 --
 Justin
 http://jcc_7.tripod.com/d/



----------------------------------------------------------------------------
----



 module mod;

 import std.c.stdio;

 struct mod
 {
 int whatever;
 }


 void main()
 {
 mod myMod;

 myMod.whatever = 1692;

 //mod myMod = new mod();
 printf("It works.\n");
 }



----------------------------------------------------------------------------
----



 module mod;

 import std.c.stdio;

 class mod
 {
 int whatever;

 this()
 {
 printf("Ok.  Let's go.\n");
 }
 }


 void main()
 {
 mod myMod = new mod();
 printf("It works.\n");
 }





 Feb 02 2004



  parent  J C Calvarese <jcc7 cox.net>  writes: