[cfe-dev] Adding a Command-Line Option to Clang

[Douglas Gregor]

On Jun 24, 2011, at 11:41 AM, John Criswell wrote:

> Dear All,
> 
> I'm trying to add a command line option to Clang/Clang++ that will tell 
> it to run some additional LLVM passes that I've written.  From what I've 
> read from the source code, it looks like I have to add an option to both 
> clang (the frontend driver) and CC1 (the actual compiler that performs 
> optimization on the LLVM IR) and somehow get the frontend driver to 
> propagate the command-line option to CC1.
> 
> Is my above conclusion correct, and if so, how do I most easily 
> propagate the command-line option from the front end to the cc1 compiler?

Yes, your conclusion is correct. The easiest way to figure out how to add a new option is to pick an existing option that gets passed down to the -cc1 level (using -### to show the -cc1 command line associated with a given clang command line), and find the places in the source where that option shows up.

	- Doug