[Interest] Qt 5 LTO build on OS X 10.9 (and earlier)

Thiago Macieira thiago.macieira at intel.com
Fri Sep 11 23:49:39 CEST 2015

On Friday 11 September 2015 20:48:39 René J. V. Bertin wrote:
> Thiago Macieira wrote:
> > If it produces "thin" objects (LLVM bitcode only), then you must use
> > llvm-ar to create the .a so that the symbol table is updated with the
> > symbols that would have been there if the .o were "fat".
> Hmmm, I actually don't know about static libraries, I hardly use them.

libQt5Bootstrap.a, libqtharfbuzzng.a, libQt5PlatformSupport.a. If you're 
trying to compile qtbase, you're building at least three of them.

> Of
> course if they end up linked into shared libraries their debug info will
> get lost with the rest. I don't suppose llvm-ar works on shared libraries,
> does it?

I have no clue what issues with debugging there might be. I haven't 
experienced that problem with GCC's LTO.

> > Actually, that has nothing to do with debugging.
> > 
> > That's just linking.
> Well, yes, it's something to do with the linker, but the end result is that
> symbolic or source-level (or whatever you wish to call it) is possible or
> not ...

I don't see any reason why the compiler would get lost.

Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center

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