[LLVMdev] Static code generation - is it gone from LLVM 2.7?

[Chris Lattner]

On Mar 27, 2010, at 1:50 PM, Peter Shugalev wrote:

> Chris Lattner wrote:
>> On Mar 27, 2010, at 12:49 PM, Peter Shugalev wrote:
>> 
>>>>> New method of emitting object code is ok for me. But it is still
>>>>> experimental, isn't it?
>>>> Yes.
>>> Thank you for answers!
>>> 
>>> Now there is a way to implement what I'd like to. But it would be MUCH
>>> better if LLVMTargetMachine::addPassesToEmitFile could take arbitrary
>>> MCStreamer as input. Without such a feature when compiling bytecode
>>> (i.e. emulating llc -filetype=obj behaviour) I have to emit .s file
>>> first, disassemble it and feed to custom MCStreamer. That'll hopely work
>>> but it's ugly.
>> 
>> What are you trying to do?  I don't see why you'd have to do that.
> 
> Ok, I'm trying to compile LLVM bytecode into some native object code
> format. The thing very close to
>> llc -filetype=obj foo.bc
> 
> To do so I mimic llc behaviour: create TargetMachine, create
> FunctionPassManager, call TargetMachine::addPassesToEmitFile(), add my
> own MyObjectCodeWriter pass and run passes.
> 
> But since LLVM 2.7 TargetMachine::addPassesToEmitFile (as implemented in
> LLVMTargetMachine child class) adds its own final pass (AsmPrinter)
> paired with either AsmStreamer, MachOStreamer or NullStreamer. I cannot
> pass my own descendant of MCStreamer class. Now we've got predefined set
> of final passes instead of free choice.

LLVM 2.7 doesn't have final support for this.  The idea is that we'd add ELF and PECOFFStreamers as well, or parameterize it a different way.

> AFAIK to get object code file I have to feed emitted code through my own
> MyMCStreamer class. The only sane option I see is to take assembly
> output from AsmStreamer (.s file) then feed it to AsmParser passing
> MyMCStreamer in AsmParser's constructor.

You're going to have to hack up the code generator to do this in 2.7

-Chris