[LLVMdev] gcc, conceptgcc, and llvm-gcc

[Bill Wendling]

On Sep 29, 2010, at 5:05 AM, Xiaolong Tang wrote:

> 
> Hey all, 
> 
> My previous work was done mainly in the front-end of conceptgcc,
> whereas recently I am doing some code analysis in the middle-end of
> llvm. I am considering to port my previous work to llvm. 
> 
> So, I am very concerned with the difference between gcc and llvm-gcc,
> and of course the difference between gcc and conceptgcc. I have no
> idea of the former difference, though I have some idea of the latter
> difference. 
> 
> Would someone briefly please point out the changes of llvm-gcc
> relative to gcc? Hopefully, with your input, I could evaluate the
> efforts when I patch a normal gcc with the differences between gcc and
> llvm-gcc :)
> 
Hi Xiaolong,

Your question doesn't have a simple answer. :-)

The differences between gcc and llvm-gcc are fairly substantial. There's the obvious point that instead of the gcc optimizers and code generators, llvm-gcc uses llvm's optimizers and code generators. In fact, llvm-gcc tries to use as little of gcc's code as possible (for instance, the code is never converted to RTL). Using only enough to parse the code and then translate it into llvm IR. (See the various llvm-* files in the llvm-gcc source tree.)

If you're wishing to port your work to llvm, might I suggest looking into clang?

	http://clang.llvm.org/

-bw