[cfe-dev] Driver support for AST features (UI Proposal)

[Fariborz Jahanian]

On Aug 31, 2009, at 10:51 PM, Daniel Dunbar wrote:

> Hi all,
>
> This is a UI design proposal for the clang driver for providing user /
> tool access to clang AST based features.
>
> 1. Support '-emit-ast'; this will be an option like '-S' in that it
> stops compilation at the AST production phase, and will generate files
> with a '.ast' suffix.
>
> 2. Recognize '.ast' files as source inputs which can be compiled.
> Obviously this will start at the compilation phase, in the same way
> that '.i' etc inputs bypass the preprocessing phase.
>    a. clang will call clang with an explicit argument telling it to
clang will call clang-cc ?
>
> compile from .ast (-compile-ast) instead of -S.
>
>
>    b. The compile-ast action will skip passing preprocessing specific
> options to clang (but still pass options used by the code generator).

Shouldn't the option for back-end be stored in the AST node during - 
emit-ast
phase? This helps, among other things with language specific issues,  
and maybe
for debug info. (if we chose to putout additional ASTs for such  
purpose).
Also, the compiler rev number would be a plus to prevent nasty bugs.

- fariborz


>
>
> Eventually we will probably also want a feature '-write-ast' (or so)
> which will output an AST while doing other things (like compiling),
> but that is not part of this proposal.
>
> One salient design point is that the default suffix for AST files is
> '.ast', which does not indicate the source language. This means the
> driver won't be able to make decisions about things like code
> generator options based on its language. I'm not sure yet if this
> matters. If it did we would either (a) have to poke the .ast to figure
> out its language, or (b) use -x with new options like c++-ast etc
> (like for preprocessed inputs) and optionally use suffixes like
> '.c-ast', '.cpp-ast', etc.
>
> Comments?
>
> A patch following this design is attached. The compile-ast option is
> not implemented in clang, and I don't know exactly what model we want
> for compile options passed to an ast -> .s compile step (most of them
> are backed in the .ast, but not all of them).
>
> - Daniel
> <0001-Initial-emit-ast- 
> support.patch>_______________________________________________
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