Subject: Re: egcs update: PE linker problem work-around
From: [email-masked] (Mikey)

29 Oct 1997 17:59:20 -0800
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To: Mumit Khan <[email-masked]>, [email-masked], [email-masked]

You are correct, ld (actually the ld/bfd interface) does not properly handle comdat sections
the Communal; sym=XXX is not recognized (I guess there was no
way to fit it into bfd?), nor is the associated section attribute recognized.
(at least I couldn't find them looking through the code, and objdump
dosen't seem to know about them)

There are quite a few binary incompatibilities like this left between cygwin32
and MS pei that need to be corrected, but it has been so long since the last
release, that I hesitate to spend time on fixes that will have to be completely
rewritten when the next version comes out.

Also since what we are waiting for right now (I assume ;^) is a rewrite of 
the bfd backend for pei to accommodate section relative symbols, Ian may 
already be fixing some of them.

Following is a list of the ones I have spotted, in trying to rewrite the
mingw32 startup files to be more MS compatible, this is not exhaustive,
just the ones I have spotted ;^)

2. The pick associative section attribute isn't implemented at all
	in cygwin32 ld? (dosen't necessarily need to be in 
		gcc, but to link MS lib's it is a must)

3. Import stubs in Import libraries need to be named 
	to the name of the exporting dll/exe CAPITOLIZED, 
	as that is the only way to distinguish a regular .obj 
	or .o file from a stub. (maybe Communal sym?)
	(this is completely undoc, but I could find no other differences)

4. The SEC_LINK_ONCE flag handling needs to be rewritten for Import stubs,
	except for SEC_LINK_ONCE_DISCARD, (idata 4&6) 
	since abfd will be the same for all

5 idata$7 dosen't exist, and needs to be eliminated, import dll 
	belongs in idata$6 of head.

6 DATA keyword for .def files needs to be added (does not 
	create a thunk or unprefixed symbol only the _imp__),
	The CONSTANT	 keyword need to be changed 
	so as not to create a thunk (.text) section.

7 CC1 needs to be fixed to allow __attribute__ ((_stdcall)) 
	between * and funcname

8 -freg-struct-return is the default for CL.EXE, and should be
	changed to the default for gcc.exe

9 One of the main reasons for problems linking with .lib files,
	is that microsoft uses _imp__ instead of __imp_ in their
	stub libraries, how could this have gone unnoticed?
	lines 1587, 1588, 1843, 1844, 1854, and 1962 of dlltool.c 
	in .../cdk/binutils need to be corrected.

10. dllimport & dllexport attributes need to be copied from .../cdk/gcc/config/arm/pe.[ch]
	to the appropriate places in .../cdk/gcc/config/i386/*

On Wed, 29 Oct 1997 00:40:31 -0600, you wrote:

>After what seems like days of suffering, I've given up on figuring what
>the problem is with egcs+gas+PE linker. Here's the problem in a nut-shell:
>egcs back-end generates named sections that are marked ".linkonce
>discard", and if you have lots of templates, you get the same benefit as
>on an ELF system. the PE linker gathers up all the named sections and
>picks one for you. Unfortunately, it looks as if there is a nasty bug 
>where the linker is not doing it's job, and you get multiply-defined
>symbols. I first thought it was the code generator, then it was gas, and 
>now I believe the problem lies in ld.
>
>To avoid this hassle, I've reverted the code generation to the old days;
>the pro is that it works, and the con is that you can't deal with
>templates like you can on an ELF system. For all currently working code
>under gcc, this shouldn't be a problem. Most of my old code that works
>with gcc-2.7.2 also works, and so does octave-2.0.9 (modified to support
>new template syntax changes in CD2).
>
>Hopefully those more familiar with BFD/gas/ld can shed some light on
>this.
>
>The new updated binary snapshot should be up shortly (URL after sig).
>
>Regards,
>Mumit -- [email-masked]
>http://www.xraylith.wisc.edu/~khan/
>http://www.xraylith.wisc.edu/~khan/software/gnu-win32
>
>-
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([email-masked])
delete REMOVETHIS from the above to reply
         Mikey
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