llvm dev - Jun 2007 - [LLVMdev] LLVM binaries for Windows and more

> -----Ursprüngliche Nachricht-----
> Von: asl at math.spbu.ru, LLVM Developers Mailing List <llvmdev at
cs.uiuc.edu>
> Gesendet: 13.06.07 23:13:08
> An: LLVM Developers Mailing List <llvmdev at cs.uiuc.edu>
> Betreff: Re: [LLVMdev] LLVM binaries for Windows and more
> 
> Hello, Andreas.
> 
> > It seems that the generated ASM code cannot be assembled with GCC
(wrong output format I guess).
> Yes, it seems, that intel-style assembler is emitted.
> 
> >  Maybe this fails because it calls the MingW gcc.exe and not
llvm-gcc.exe?
> No. LLVM autodetects platform you're running tools on. So, the problem
> actually is that you're trying to "mix" binaries built with
microsoft
> tools with gcc. The first will force LLVM tools to emit intel-style
> assembler (in fact, masm-dialect), but second will assume, that you're
> providing AT&T style assembler on input.
> 
> Possible solutions:
> 1. Either build LLVM with gcc on mingw32 platform
> 2. Select assembler flavour "by hands" (look into llc --help to
find,
> how to do this)
I tried solution 2 and it works! Thank you!

> 3. Implement necessary functionality in llvm-ld (calling microsoft
> tools, if intel-style assembler is emitted).
> 
> >  However, is the name "a.out.s" a bug?
> No.
> 
Ok, but it remains strange :-).
> > Is it planed to include binary writers?
> Maybe. Patches are welcome :) In fact, there are MachO and ELF writers.
> Both misses many important things.
> 
> > (So that the step to go through an external assembler wouldn't be
necessary.)
> This isn't totally right: consider you have the source with inline
> assembler.
> 
Hm, either the assembler parser could be integrated (GCC seems to be doing this
with cryptic ways to specify which registers get changed :-) or only those files
could be assembled by an external assembler. Am I the only one who thinks
emitting huge ASM files is a bad idea for compile-time performance?
Targetting LLVM as a backend currently seems to imply the following
"pipeline":

Programming language (needs to be parsed) --> LLVM code (textual; needs to be
parsed) --> Assembler (textual; needs to be parsed) --> Executable

I don't want to be offensive here; just curious how you see it. (Yes, I know
one could output LLVM's bitcode directly. However, I wouldn't dare;
probably for the same reasons LLVM does output textual assembly.)

Thanks again,
Andreas

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On 14 jun 2007, at 00:58, Andreas Rumpf wrote:
> Am I the only one who thinks emitting huge ASM files is a bad idea  
> for compile-time performance?
Most open source compilers work that way. The advantage is that you  
don't have to spend time on integrating and maintaining an assembler  
yourself, and instead can spend your time on optimizations and other  
interesting stuff.


Jonas

>I don't want to be offensive here; just curious how you see it. (Yes, I 
>know one could >output LLVM's bitcode directly. However, I
wouldn't dare;
>probably for the same >reasons LLVM does output textual assembly.)
I believe there are libraries to do this for you.

Aaron