[cfe-dev] Embedding Compiler Invocation in Object Files

[Steven Wu via cfe-dev]

There is an alternative which comes partially with -fembed-bitcode=all option is that the compiler invocation (-cc1 commands) are embedded in a special section in the object file). This comes as a side-affect of embedding full bitcode but we can clean up the code to embed command line only without bitcode.

Steven


> On Jun 14, 2016, at 7:15 PM, Saleem Abdulrasool via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
> 
> On Tue, Jun 14, 2016 at 6:40 PM, Sean Silva <chisophugis at gmail.com <mailto:chisophugis at gmail.com>> wrote:
> 
> 
> On Tue, Jun 14, 2016 at 5:42 PM, Saleem Abdulrasool via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
> On Tue, Jun 14, 2016 at 10:07 AM, Keno Fischer via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
> I wanted to revive the idea of adding a feature that would have clang embed its invocation in the created object file (like a compilation database, but internal to the object file). I know this was discussed on the mailing list a few years ago, but as far as I'm aware, there wasn't any progress on this. My use case for this is debugging (rather than reconstruct a clang AST from debug info, just re-parse the correct translation unit and get the complete AST), but I know there are other people interested in this functionality as well. For my use case, I think I'd be happy associating this with the DWARF compilation unit (how to represent this would be something to be discussed, putting it into DW_AT_producer is probably simplest, but there may be other options). Thoughts?
> 
> If you wish to embed it into the DWARF data, then there is a well tested vendor extension that Apple has in LLVM: DW_AT_APPLE_flags.
> 
> That said, I was already looking at adding similar functionality for compatibility with GCC (-frecord-gcc-switches).  The way that this works is that there is a special section embedded which contains an array of C strings which is the command line.  The recorded invocation is the *compiler* invocation, not the driver invocation.
> 
> Neat; I didn't know about this GCC option. Apparently there is also a -grecord-gcc-switches which uses DW_AT_producer:
> 
> """
> This switch causes the command-line options used to invoke the compiler that may affect code generation to be appended to the DW_AT_producer attribute in DWARF debugging information. The options are concatenated with spaces separating them from each other and from the compiler version. It is enabled by default. See also -frecord-gcc-switches for another way of storing compiler options into the object file. 
> """ - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html <https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html>
> 
> Yeah, the -grecord-gcc-switches is slightly different in that it records a subset of them (code generation effecting ones only).
>  
> -- Sean Silva
> 
>  
>  
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
> 
> 
> 
> 
> -- 
> Saleem Abdulrasool
> compnerd (at) compnerd (dot) org
> 
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
> 
> 
> 
> 
> 
> -- 
> Saleem Abdulrasool
> compnerd (at) compnerd (dot) org
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20160615/1875ff16/attachment.html>