[dmd-beta] dmd 1.070 and 2.055 beta

[Rainer Schuetze]

On 06.09.2011 23:05, Rainer Schuetze wrote:
> On 06.09.2011 22:51, Rainer Schuetze wrote:
>> On 06.09.2011 22:45, Walter Bright wrote:
>>>
>>>
>>> On 9/6/2011 12:13 PM, Rainer Schuetze wrote:
>>>>
>>>> I can reproduce the issue on Win7 64, but not on XP. I have 
>>>> debugged it a little until I noticed that the generated code for 
>>>> TLS access seems broken:
>>>>
>>>> dmd 2.054 generated this code for the append operation
>>>>
>>>>  push        1
>>>> 1000207D  mov         ecx,dword ptr [__tls_index (1006BF98h)]
>>>> 10002083  mov         edx,dword ptr fs:[2Ch]
>>>> 1000208A  mov         ebx,dword ptr [edx+ecx*4]
>>>> 1000208D  lea         esi,[ebx+4]
>>>> 10002093  push        esi
>>>> 10002094  mov         eax,offset TypeInfo_Ai at __init (1005E9A0h)
>>>> 10002099  push        eax
>>>> 1000209A  call        __d_arrayappendcT (10004D68h)
>>>>
>>>> while the beta generates
>>>>
>>>> push        1
>>>> 10002076  mov         ecx,dword ptr fs:[2Ch]
>>>> 1000207D  mov         edx,dword ptr [ecx]
>>>> 1000207F  lea         ebx,[edx+4]
>>>> 10002085  push        ebx
>>>> 10002086  mov         esi,offset TypeInfo_Ai at __init (10067A90h)
>>>> 1000208B  push        esi
>>>> 1000208C  call        __d_arrayappendcT (10004F9Ch)
>>>>
>>>> so it completely ignores the tls_index. I guess it works on XP 
>>>> because there are less DLLs that use TLS, so the DLLs index ends up 
>>>> as 0.
>>>>
>>>
>>> Very interesting. Can you provide the source code for that?
>>>
>>>
>>> _______________________________________________
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>>> dmd-beta at puremagic.com
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>> it seems to happen with any code:
>>
>> int x;
>>
>> int main()
>> {
>>         return x;
>> }
>>
>> generates
>>
>> __Dmain comdat
>>         assume  CS:__Dmain
>>                 mov     EAX,FS:__tls_array
>>                 mov     ECX,[EAX]
>>                 mov     EAX,_D1m1xi[ECX]
>>                 ret
>> __Dmain ends
>>
>
> Sorry, this is wrong. This is the usual exe-only optimization that 
> assumes tls_index==0. It seems the command line options do not suggest 
> that a DLL is generated. I'll try to reduce it...
>

A simple example is this:

module dllmain;
import std.c.windows.windows;

int test;

extern (Windows)
BOOL DllMain(HINSTANCE hInstance, ULONG ulReason, LPVOID pvReserved)
{
     test = 1;
     return true;
}

to be compiled with
dmd -g -v -oftest.dll dll.def -L/SUBSYSTEM:WINDOWS dllmain.d


The problem is, that backend_init() is called before the files on the 
command line are processed. So, global.params.deffile is always 0 when 
config.wflags is set in out_config_init(), and the code generation 
thinks it is generating an executable.

Though unused by dmd, the deffile looks like this for completeness:
LIBRARY "test.dll"
  EXETYPE NT
  SUBSYSTEM WINDOWS
  CODE SHARED EXECUTE
  DATA WRITE
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