hello! I used to have a bit unusual task: writing pure binary code (without runtime/os dependency, just native x86 and x64 code). Quite similar to the OS kernel development I may say, if it makes the problem clearer for you. I usually wrote such code in C++ with GCC (using '-nostdlib', '-fno-exceptions', '-fno-rtti' and etc), but now I need a good metaprogramming features and complex metaprogramming in C++ makes a brain explode. D metaprogramming and the language in general looks awesome, so I decided to give it a try.

I looked at the XOMB and a few other projects, but it seems they reimplemented quite big part of druntime to make their project work, in fact a lot of stuff reimplemented by them I would consider being actually useless. So my question is: how much of the runtime features I could disable?

for testing purposes I made a little programm (I'm building it with '-nophoboslib', '-nostdlib', '-fno-exceptions', '-emain'):

module main;

extern (C) void* _Dmodule_ref = null;
extern (C) void puts(const char*);
extern (C) void exit(int);

extern (C) void main() {
	scope(exit) {
		puts("Exiting!");
		exit(0);
	}
	
	puts("Hello World!");
}

I had to include '_Dmodule_ref' in the source, it seems that it is used for calling module constructors, I'm not going to use them, can I disable it somehow?

when I added 'scope(exit)' part I got links to exception handling code in object files, I'm not going to use exceptions, so I added '-fno-exceptions' flag, and it seems to work pretty fine. but when I try to add some primitive classese I got a lot of links to the code that seems to be connected with runtime type information, I don't need it so I tried to add '-fno-rtti' flag, but it doesn't work. Is there a way to get rid of runtime type information?

Am 11.05.2013 17:51, schrieb Rel:
> hello! I used to have a bit unusual task: writing pure binary code
> (without runtime/os dependency, just native x86 and x64 code). Quite
> similar to the OS kernel development I may say, if it makes the problem
> clearer for you. I usually wrote such code in C++ with GCC (using
> '-nostdlib', '-fno-exceptions', '-fno-rtti' and etc), but now I need a
> good metaprogramming features and complex metaprogramming in C++ makes a
> brain explode. D metaprogramming and the language in general looks
> awesome, so I decided to give it a try.
>
> I looked at the XOMB and a few other projects, but it seems they
> reimplemented quite big part of druntime to make their project work, in
> fact a lot of stuff reimplemented by them I would consider being
> actually useless. So my question is: how much of the runtime features I
> could disable?
>
> for testing purposes I made a little programm (I'm building it with
> '-nophoboslib', '-nostdlib', '-fno-exceptions', '-emain'):
>
> module main;
>
> extern (C) void* _Dmodule_ref = null;
> extern (C) void puts(const char*);
> extern (C) void exit(int);
>
> extern (C) void main() {
>      scope(exit) {
>          puts("Exiting!");
>          exit(0);
>      }
>
>      puts("Hello World!");
> }
>
> I had to include '_Dmodule_ref' in the source, it seems that it is used
> for calling module constructors, I'm not going to use them, can I
> disable it somehow?
>
> when I added 'scope(exit)' part I got links to exception handling code
> in object files, I'm not going to use exceptions, so I added
> '-fno-exceptions' flag, and it seems to work pretty fine. but when I try
> to add some primitive classese I got a lot of links to the code that
> seems to be connected with runtime type information, I don't need it so
> I tried to add '-fno-rtti' flag, but it doesn't work. Is there a way to
> get rid of runtime type information?

GDC has -nodefaultlib flag which will disable linking against the standard library. This is as bare metal as it gets, just start writing all functions you will get linker errors for. Be warned a lot of language features will break that way, eg:

- Everything that relies on the GC (closures, array literals, etc)
- Module Constructors / Destructors
- Thread local storage

I've also seen that there is a minmal druntime somewhere on the web, but I can't find it right now.

Kind Regards
Benjamin Thaut

Benjamin Thaut, yes I know. but here is an example, if I add a class to the code like that:

module main;

extern (C) void* _Dmodule_ref = null;
extern (C) void printf(const char*, ...);
extern (C) void puts(const char*);
extern (C) void exit(int);

class A {
	int a = 100;
	int b = 200;
};

extern (C) void main() {
	scope(exit) {
		puts("Exiting!");
		exit(0);
	}

	A a; printf("%d %d\n", a.a, a.b);
}

I would get a lot of undefined symbols like '_D14TypeInfo_Class6__vtblZ', '_D6object6Object8toStringMFZAya', '_D6object6Object6toHashMFZk' and etc. I don't really need any runtime type information, is there a way to make a compiler not generating typeinfos ('-fno-rtti' doesn't work)?

On 11 May 2013 16:51, Rel <relmail@rambler.ru> wrote:

> hello! I used to have a bit unusual task: writing pure binary code (without runtime/os dependency, just native x86 and x64 code). Quite similar to the OS kernel development I may say, if it makes the problem clearer for you. I usually wrote such code in C++ with GCC (using '-nostdlib', '-fno-exceptions', '-fno-rtti' and etc), but now I need a good metaprogramming features and complex metaprogramming in C++ makes a brain explode. D metaprogramming and the language in general looks awesome, so I decided to give it a try.
>
> I looked at the XOMB and a few other projects, but it seems they reimplemented quite big part of druntime to make their project work, in fact a lot of stuff reimplemented by them I would consider being actually useless. So my question is: how much of the runtime features I could disable?
>
> for testing purposes I made a little programm (I'm building it with '-nophoboslib', '-nostdlib', '-fno-exceptions', '-emain'):
>
> module main;
>
> extern (C) void* _Dmodule_ref = null;
> extern (C) void puts(const char*);
> extern (C) void exit(int);
>
> extern (C) void main() {
>         scope(exit) {
>                 puts("Exiting!");
>                 exit(0);
>         }
>
>         puts("Hello World!");
> }
>
> I had to include '_Dmodule_ref' in the source, it seems that it is used for calling module constructors, I'm not going to use them, can I disable it somehow?
>
> when I added 'scope(exit)' part I got links to exception handling code in object files, I'm not going to use exceptions, so I added '-fno-exceptions' flag, and it seems to work pretty fine. but when I try to add some primitive classese I got a lot of links to the code that seems to be connected with runtime type information, I don't need it so I tried to add '-fno-rtti' flag, but it doesn't work. Is there a way to get rid of runtime type information?
>


-nophoboslib tells the driver not to link to phobos/druntime.

-nostdlib tells the driver not to link to any C libs.

-fno-exceptions only puts in an error if it encounters a 'throw' statement.  Doesn't actually prevent the front-end from generating throw/try/catch statements on the fly, or do anything that causes an exception to be raised, and I don't think it errors about the use of assert contracts either.  Looking at the above, you use scope() statements.  This really is just a nice way of expressing try { }  catch { } finally { } without all the nested blocks.

-fno-rtti is not adhered to, infact I didn't realise that it was even a common compiler switch  (thought it was only in g++).   This could be added in, not should on how good an idea it would be though... :)

_Dmodule_ref should be possible to not define this via a compiler flag, but that has not yet been implemented.


-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';

On 12 May 2013 15:41, Rel <relmail@rambler.ru> wrote:

> Benjamin Thaut, yes I know. but here is an example, if I add a class to the code like that:
>
>
> module main;
>
> extern (C) void* _Dmodule_ref = null;
> extern (C) void printf(const char*, ...);
>
> extern (C) void puts(const char*);
> extern (C) void exit(int);
>
> class A {
>         int a = 100;
>         int b = 200;
>
> };
>
> extern (C) void main() {
>         scope(exit) {
>                 puts("Exiting!");
>                 exit(0);
>         }
>
>         A a; printf("%d %d\n", a.a, a.b);
> }
>
> I would get a lot of undefined symbols like '_D14TypeInfo_Class6__vtblZ', '_**D6object6Object8toStringMFZAya**', '_D6object6Object6toHashMFZk' and etc. I don't really need any runtime type information, is there a way to make a compiler not generating typeinfos ('-fno-rtti' doesn't work)?
>

If you want to use classes, there must *always* be an Object class defined somewhere to link to.  All classes derive from Object.

-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';

On 12 May 2013 15:41, Rel <relmail@rambler.ru> wrote:

> Benjamin Thaut, yes I know. but here is an example, if I add a class to the code like that:
>
>
> module main;
>
> extern (C) void* _Dmodule_ref = null;
> extern (C) void printf(const char*, ...);
>
> extern (C) void puts(const char*);
> extern (C) void exit(int);
>
> class A {
>         int a = 100;
>         int b = 200;
>
> };
>
> extern (C) void main() {
>         scope(exit) {
>                 puts("Exiting!");
>                 exit(0);
>         }
>
>         A a; printf("%d %d\n", a.a, a.b);
> }
>

This code won't work.  classes are reference types and need to be
initialised with 'new'.  This requires TypeInfo_Class information to
do...   You could possible use 'scope A a = new A'.  But again your going
into the bounds of needing rtti for the initialiser var to assign it on the
stack.

Structs would be your friend here...

-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';

On Sunday, 12 May 2013 at 15:27:04 UTC, Iain Buclaw wrote:
> On 12 May 2013 15:41, Rel <relmail@rambler.ru> wrote:
>
>> Benjamin Thaut, yes I know. but here is an example, if I add a class to
>> the code like that:
>>
>>
>> module main;
>>
>> extern (C) void* _Dmodule_ref = null;
>> extern (C) void printf(const char*, ...);
>>
>> extern (C) void puts(const char*);
>> extern (C) void exit(int);
>>
>> class A {
>>         int a = 100;
>>         int b = 200;
>>
>> };
>>
>> extern (C) void main() {
>>         scope(exit) {
>>                 puts("Exiting!");
>>                 exit(0);
>>         }
>>
>>         A a; printf("%d %d\n", a.a, a.b);
>> }
>>
>
> This code won't work.  classes are reference types and need to be
> initialised with 'new'.  This requires TypeInfo_Class information to
> do...   You could possible use 'scope A a = new A'.  But again your going
> into the bounds of needing rtti for the initialiser var to assign it on the
> stack.
>
> Structs would be your friend here...

I have used the option -fno-emit-moduleinfo and got rid of _Dmodule_ref

Anything created with 'new' needs memory allocation. I have just published a minimum memory allocation in my repo.

The address of my minimum runtime environment repository is:
bitbucket.org/timosi/minlibd

On 12 May 2013 18:13, Timo Sintonen <t.sintonen@luukku.com> wrote:

> On Sunday, 12 May 2013 at 15:27:04 UTC, Iain Buclaw wrote:
>
>> On 12 May 2013 15:41, Rel <relmail@rambler.ru> wrote:
>>
>>  Benjamin Thaut, yes I know. but here is an example, if I add a class to
>>> the code like that:
>>>
>>>
>>> module main;
>>>
>>> extern (C) void* _Dmodule_ref = null;
>>> extern (C) void printf(const char*, ...);
>>>
>>> extern (C) void puts(const char*);
>>> extern (C) void exit(int);
>>>
>>> class A {
>>>         int a = 100;
>>>         int b = 200;
>>>
>>> };
>>>
>>> extern (C) void main() {
>>>         scope(exit) {
>>>                 puts("Exiting!");
>>>                 exit(0);
>>>         }
>>>
>>>         A a; printf("%d %d\n", a.a, a.b);
>>> }
>>>
>>>
>> This code won't work.  classes are reference types and need to be
>> initialised with 'new'.  This requires TypeInfo_Class information to
>> do...   You could possible use 'scope A a = new A'.  But again your going
>> into the bounds of needing rtti for the initialiser var to assign it on
>> the
>> stack.
>>
>> Structs would be your friend here...
>>
>
> I have used the option -fno-emit-moduleinfo and got rid of _Dmodule_ref
>

I completely forgot that I put that in.  Well done me *pats own back*.

-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';

Last time I tried such stuff there was a TypeInfo emitted for templated structs. Is this still the case?

On 13 May 2013 09:11, Dicebot <m.strashun@gmail.com> wrote:

> Last time I tried such stuff there was a TypeInfo emitted for templated structs. Is this still the case?
>

Why would you use templates in low level (eg: kernel) code?

-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';