Re: linking application with a library

Re: linking application with a library

[Kai Ruottu]

Mohammad Saleem wrote:
> 
> Hi all,
> 
> I am using h8300-hitachi-hms-gcc cross-complier for building my application.
> I have a lib mylib.a (20 kb) which I want to link with my application.
> My application gets 20 kb bigger as soon as I link it with mylib.a
> without any function being called from mylib.a.

 The linker shouldn't take anything from the lib if it doesn't need anything
from it.

> It seems to me that I have built mylib.a so that the whole lib is linked
> during linking process even if no one method is being called.

 Is the library produced using C++ or ObjC or from where the name 'method'
comes?

> Now my question is which flag should I use to build mylib.a so that only
> those functions are linked which are being called.

 Compiling each function into its own '.o' module is the normal practice,
the linker takes only the needed '.o' files from the archive.
 
> If no function is called then linking mylib.a shouldn't affect the size
> of my application.

 Yes, this should be the case...

 BTW, the H8/300 is a architecture which requires tricks like using
the '__attribute__((eightbit_data))' for the SFRs (I/O-registers) in
order to produce any effective code...  For instance:

-------------------- clip --------------------------------
#define SFR       __attribute__((eightbit_data))

extern volatile unsigned char SFR SCI_SSR0;
extern volatile unsigned char SFR SCI_TDR0;

/*
#define SCI_TDR0 (*(volatile unsigned char *) (0xffffdb))
#define SCI_SSR0 (*(volatile unsigned char *) (0xffffdc))
*/

/* Single char out to the serial port */

void put_ser(unsigned char c)
{
        while ((SCI_SSR0 & 0x80) != 0x80)
                ;
        SCI_TDR0 = c;
        SCI_SSR0 &= 0x7F;
}
-------------------- clip --------------------------------
;       GCC For the Hitachi H8/300
;       By Hitachi America Ltd and Cygnus Support
;       release F-1
; -O2

        .h8300s
        .file   "put_ser.c"
        .section .text
        .align 1
        .global _put_ser
_put_ser:
.L5:
        mov.b   @_SCI_SSR0:8,r2l
        and     #128,r2l
        beq     .L5
        mov.b   r0l,@_SCI_TDR0:8
        bclr    #7,@_SCI_SSR0:8
        rts
        .end
-------------------- clip --------------------------------

 Getting a RISC-like 'load/and/store' operation instead of the
'bclr #7,@_SCI_SSR0:8' is not rare if not using any of these
'tricks'... And if the I/O-ports are used much, much 'code
bloat' will be the result...

Cheers, Kai



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Re: linking application with a library

[Mohammad Saleem]

Hi Kai,

Thanks for answer.
regards

/Mohammad

Kai Ruottu wrote:

>Mohammad Saleem wrote:
>
>>Hi all,
>>
>>I am using h8300-hitachi-hms-gcc cross-complier for building my application.
>>I have a lib mylib.a (20 kb) which I want to link with my application.
>>My application gets 20 kb bigger as soon as I link it with mylib.a
>>without any function being called from mylib.a.
>>
>
> The linker shouldn't take anything from the lib if it doesn't need anything
>from it.
>
>>It seems to me that I have built mylib.a so that the whole lib is linked
>>during linking process even if no one method is being called.
>>
>
> Is the library produced using C++ or ObjC or from where the name 'method'
>comes?
>
>>Now my question is which flag should I use to build mylib.a so that only
>>those functions are linked which are being called.
>>
>
> Compiling each function into its own '.o' module is the normal practice,
>the linker takes only the needed '.o' files from the archive.
> 
>
>>If no function is called then linking mylib.a shouldn't affect the size
>>of my application.
>>
>
> Yes, this should be the case...
>
> BTW, the H8/300 is a architecture which requires tricks like using
>the '__attribute__((eightbit_data))' for the SFRs (I/O-registers) in
>order to produce any effective code...  For instance:
>
>-------------------- clip --------------------------------
>#define SFR       __attribute__((eightbit_data))
>
>extern volatile unsigned char SFR SCI_SSR0;
>extern volatile unsigned char SFR SCI_TDR0;
>
>/*
>#define SCI_TDR0 (*(volatile unsigned char *) (0xffffdb))
>#define SCI_SSR0 (*(volatile unsigned char *) (0xffffdc))
>*/
>
>/* Single char out to the serial port */
>
>void put_ser(unsigned char c)
>{
>        while ((SCI_SSR0 & 0x80) != 0x80)
>                ;
>        SCI_TDR0 = c;
>        SCI_SSR0 &= 0x7F;
>}
>-------------------- clip --------------------------------
>;       GCC For the Hitachi H8/300
>;       By Hitachi America Ltd and Cygnus Support
>;       release F-1
>; -O2
>
>        .h8300s
>        .file   "put_ser.c"
>        .section .text
>        .align 1
>        .global _put_ser
>_put_ser:
>.L5:
>        mov.b   @_SCI_SSR0:8,r2l
>        and     #128,r2l
>        beq     .L5
>        mov.b   r0l,@_SCI_TDR0:8
>        bclr    #7,@_SCI_SSR0:8
>        rts
>        .end
>-------------------- clip --------------------------------
>
> Getting a RISC-like 'load/and/store' operation instead of the
>'bclr #7,@_SCI_SSR0:8' is not rare if not using any of these
>'tricks'... And if the I/O-ports are used much, much 'code
>bloat' will be the result...
>
>Cheers, Kai
>
>
>



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RE: linking application with a library

[David Korn]

-----Original Message-----
>From: Mohammad Saleem [mailto:mosa@enea.se]
>Sent: 18 November 2001 11:46

  Hiya Mohammad, I can see a couple of things here:

>Even with link I tried with a flag --gc-sections 

  D'oh, yes, sorry, I should have mentioned that one.

>test.srec: $(OBJ) appcon.o
>    $(LD) --gc-sections $(LDFLAGS)   $^ mylib.a $(LIBS) -o $@

  But you are linking mylib.a as if it were an object file!  I think it
needs to be supplied with a -l flag to be treated as a library, does it
not ?  Try renaming mylib.a to libmylib.a (ld requires the name to be in
the format libXXXX.a and then you use -lXXXX), and then try using the
ld line in the makefile like

>    $(LD) --gc-sections $(LDFLAGS)   $^ -lmylib -L. $(LIBS) -o $@

 - ie we tell it that we want the library mylib, it knows then to look for
'libmylib.a', and the -L. tells it that the lib may be found in the 
current directory.

>********************************************
>compiling appcon.c
>h8300-hitachi-hms-ld: warning: no memory region specified for section `.
>_init'
>h8300-hitachi-hms-ld: warning: no memory region specified for section 
>`.configu'
>h8300-hitachi-hms-ld: warning: no memory region specified for section 
>`.timerIn'
>*************************************************

  This may reflect a problem with the srec format limiting the length of
section name strings, but see if it goes away when you try the new flags.

       DaveK
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linking application with a library

[Mohammad Saleem]

Hi all,

I am using h8300-hitachi-hms-gcc cross-complier for building my application.
I have a lib mylib.a (20 kb) which I want to link with my application.
My application gets 20 kb bigger as soon as I link it with mylib.a 
without any function being called from mylib.a.
It seems to me that I have built mylib.a so that the whole lib is linked 
during linking process even if no one method is being called.
Now my question is which flag should I use to build mylib.a so that only 
those functions are linked which are being called.
If no function is called then linking mylib.a shouldn't affect the size 
of my application.

Thanks for help.

regards
/Mohammad


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Re: linking application with a library

[vipin aravind]

[-- Attachment #1: Type: text/plain, Size: 1236 bytes --]

I  think you  are  static linking  thats  why.  its a  choice  if you  want
to dynamically link  the  library in which case it would  have  stubs  which
does the getprocaddress  internally at runtime  while  the actual code
resides in the dll and hence  your  executeable code  would  become small in
size.
vipin

> Hi all,
>
> I am using h8300-hitachi-hms-gcc cross-complier for building my
application.
> I have a lib mylib.a (20 kb) which I want to link with my application.
> My application gets 20 kb bigger as soon as I link it with mylib.a
> without any function being called from mylib.a.
> It seems to me that I have built mylib.a so that the whole lib is linked
> during linking process even if no one method is being called.
> Now my question is which flag should I use to build mylib.a so that only
> those functions are linked which are being called.
> If no function is called then linking mylib.a shouldn't affect the size
> of my application.
>
> Thanks for help.
>
> regards
> /Mohammad
>
>
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Re: linking application with a library

[Mohammad Saleem]

Hi David,

Thanks for your input.

I tried with the flags you mentioned in your mail like:

# how to compile C source
%.o: %.c
    @echo compiling $<
    $(CC) -ffunction-sections -fdata-sections $(CFLAGS)  $(INCLUDE) $< 
-o    $@
   
Even with link I tried with a flag --gc-sections (found by searching in 
mail archives) like:

test.srec: $(OBJ) appcon.o
    $(LD) --gc-sections $(LDFLAGS)   $^ mylib.a $(LIBS) -o $@
   


But still I get the same size of srec as before, i.e my application is 
increased by the size of mylib.a even without any function call from 
mylib.a, along with a number of warnings like:

********************************************
compiling appcon.c
h8300-hitachi-hms-ld: warning: no memory region specified for section 
`._init'
h8300-hitachi-hms-ld: warning: no memory region specified for section 
`.configu'
h8300-hitachi-hms-ld: warning: no memory region specified for section 
`.timerIn'
*************************************************

What am I doing something wrong?

regards

/Mohammad



David Korn wrote:

>>-----Original Message-----
>>From: Mohammad Saleem [mailto:mosa@enea.se]
>>Sent: 18 November 2001 10:36
>>
>
>
>>I have a lib mylib.a (20 kb) which I want to link with my application.
>>My application gets 20 kb bigger as soon as I link it with mylib.a 
>>without any function being called from mylib.a.
>>It seems to me that I have built mylib.a so that the whole lib 
>>is linked 
>>during linking process even if no one method is being called.
>>Now my question is which flag should I use to build mylib.a so 
>>that only 
>>those functions are linked which are being called.
>>If no function is called then linking mylib.a shouldn't affect 
>>the size 
>>of my application.
>>
>
>  Alas, the linker is fairly dumb, and can only include or exclude parts
>of a lib file on the basis of the section name (.text, .data or .bss).
>
>  Fortunately the compiler is fairly smart, and has an option
>-ffunction-sections that puts every function in a different section.  This
>should supposedly do the job you wish.
>
>      DaveK
>




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Re: linking application with a library

[anitak]

Hi Mohammad,
The --gc-sections remove unwanted section. But I think it is implemented
only for ELF for some targets. For hms it does not work. Try with
h8300-elf-ld.
Regards,
Anita Kulkarni

----- Original Message -----
From: Mohammad Saleem <mosa@enea.se>
To: <cygwin@cygwin.com>; <crossgcc@sources.redhat.com>
Sent: Sunday, November 18, 2001 5:25 PM
Subject: Re: linking application with a library


> Hi David,
>
> Thanks for your input.
>
> I tried with the flags you mentioned in your mail like:
>
> # how to compile C source
> %.o: %.c
>     @echo compiling $<
>     $(CC) -ffunction-sections -fdata-sections $(CFLAGS)  $(INCLUDE) $<
> -o    $@
>
> Even with link I tried with a flag --gc-sections (found by searching in
> mail archives) like:
>
> test.srec: $(OBJ) appcon.o
>     $(LD) --gc-sections $(LDFLAGS)   $^ mylib.a $(LIBS) -o $@
>
>
>
> But still I get the same size of srec as before, i.e my application is
> increased by the size of mylib.a even without any function call from
> mylib.a, along with a number of warnings like:
>
> ********************************************
> compiling appcon.c
> h8300-hitachi-hms-ld: warning: no memory region specified for section
> `._init'
> h8300-hitachi-hms-ld: warning: no memory region specified for section
> `.configu'
> h8300-hitachi-hms-ld: warning: no memory region specified for section
> `.timerIn'
> *************************************************
>
> What am I doing something wrong?
>
> regards
>
> /Mohammad
>
>
>
> David Korn wrote:
>
> >>-----Original Message-----
> >>From: Mohammad Saleem [mailto:mosa@enea.se]
> >>Sent: 18 November 2001 10:36
> >>
> >
> >
> >>I have a lib mylib.a (20 kb) which I want to link with my application.
> >>My application gets 20 kb bigger as soon as I link it with mylib.a
> >>without any function being called from mylib.a.
> >>It seems to me that I have built mylib.a so that the whole lib
> >>is linked
> >>during linking process even if no one method is being called.
> >>Now my question is which flag should I use to build mylib.a so
> >>that only
> >>those functions are linked which are being called.
> >>If no function is called then linking mylib.a shouldn't affect
> >>the size
> >>of my application.
> >>
> >
> >  Alas, the linker is fairly dumb, and can only include or exclude parts
> >of a lib file on the basis of the section name (.text, .data or .bss).
> >
> >  Fortunately the compiler is fairly smart, and has an option
> >-ffunction-sections that puts every function in a different section.
This
> >should supposedly do the job you wish.
> >
> >      DaveK
> >
>
>
>
>
> ------
> Want more information?  See the CrossGCC FAQ,
http://www.objsw.com/CrossGCC/
> Want to unsubscribe? Send a note to
crossgcc-unsubscribe@sourceware.cygnus.com
>


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Re: linking application with a library

[anitak]

Hi Mohammad,
The --gc-sections remove unwanted section. But I think it is implemented
only for ELF for some targets. For hms it does not work. Try with
h8300-elf-ld.
Regards,
Anita Kulkarni

----- Original Message -----
From: Mohammad Saleem <mosa@enea.se>
To: <cygwin@cygwin.com>; <crossgcc@sources.redhat.com>
Sent: Sunday, November 18, 2001 5:25 PM
Subject: Re: linking application with a library


> Hi David,
>
> Thanks for your input.
>
> I tried with the flags you mentioned in your mail like:
>
> # how to compile C source
> %.o: %.c
>     @echo compiling $<
>     $(CC) -ffunction-sections -fdata-sections $(CFLAGS)  $(INCLUDE) $<
> -o    $@
>
> Even with link I tried with a flag --gc-sections (found by searching in
> mail archives) like:
>
> test.srec: $(OBJ) appcon.o
>     $(LD) --gc-sections $(LDFLAGS)   $^ mylib.a $(LIBS) -o $@
>
>
>
> But still I get the same size of srec as before, i.e my application is
> increased by the size of mylib.a even without any function call from
> mylib.a, along with a number of warnings like:
>
> ********************************************
> compiling appcon.c
> h8300-hitachi-hms-ld: warning: no memory region specified for section
> `._init'
> h8300-hitachi-hms-ld: warning: no memory region specified for section
> `.configu'
> h8300-hitachi-hms-ld: warning: no memory region specified for section
> `.timerIn'
> *************************************************
>
> What am I doing something wrong?
>
> regards
>
> /Mohammad
>
>
>
> David Korn wrote:
>
> >>-----Original Message-----
> >>From: Mohammad Saleem [ mailto:mosa@enea.se ]
> >>Sent: 18 November 2001 10:36
> >>
> >
> >
> >>I have a lib mylib.a (20 kb) which I want to link with my application.
> >>My application gets 20 kb bigger as soon as I link it with mylib.a
> >>without any function being called from mylib.a.
> >>It seems to me that I have built mylib.a so that the whole lib
> >>is linked
> >>during linking process even if no one method is being called.
> >>Now my question is which flag should I use to build mylib.a so
> >>that only
> >>those functions are linked which are being called.
> >>If no function is called then linking mylib.a shouldn't affect
> >>the size
> >>of my application.
> >>
> >
> >  Alas, the linker is fairly dumb, and can only include or exclude parts
> >of a lib file on the basis of the section name (.text, .data or .bss).
> >
> >  Fortunately the compiler is fairly smart, and has an option
> >-ffunction-sections that puts every function in a different section.
This
> >should supposedly do the job you wish.
> >
> >      DaveK
> >
>
>
>
>
> ------
> Want more information?  See the CrossGCC FAQ,
http://www.objsw.com/CrossGCC/
> Want to unsubscribe? Send a note to
crossgcc-unsubscribe@sourceware.cygnus.com
>


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RE: linking application with a library

[David Korn]

>-----Original Message-----
>From: Mohammad Saleem [mailto:mosa@enea.se]
>Sent: 18 November 2001 10:36


>I have a lib mylib.a (20 kb) which I want to link with my application.
>My application gets 20 kb bigger as soon as I link it with mylib.a 
>without any function being called from mylib.a.
>It seems to me that I have built mylib.a so that the whole lib 
>is linked 
>during linking process even if no one method is being called.
>Now my question is which flag should I use to build mylib.a so 
>that only 
>those functions are linked which are being called.
>If no function is called then linking mylib.a shouldn't affect 
>the size 
>of my application.

  Alas, the linker is fairly dumb, and can only include or exclude parts
of a lib file on the basis of the section name (.text, .data or .bss).

  Fortunately the compiler is fairly smart, and has an option
-ffunction-sections that puts every function in a different section.  This
should supposedly do the job you wish.

      DaveK
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