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Re: [PR lto/41528] Add internal documentation in doc/lto.texi
- From: Richard Guenther <rguenther at suse dot de>
- To: Ralf Wildenhues <Ralf dot Wildenhues at gmx dot de>
- Cc: Diego Novillo <dnovillo at google dot com>, gcc-patches at gcc dot gnu dot org, jh at suse dot cz, David Li <davidxl at google dot com>
- Date: Wed, 17 Nov 2010 10:59:04 +0100 (CET)
- Subject: Re: [PR lto/41528] Add internal documentation in doc/lto.texi
- References: <20101115062311.GA26274@google.com> <20101116183433.GC2266@gmx.de>
On Tue, 16 Nov 2010, Ralf Wildenhues wrote:
> Hello,
>
> * Diego Novillo wrote on Mon, Nov 15, 2010 at 07:23:15AM CET:
> > +optimized builds. A, perhaps surprising, side effect of this feature
> > +is that any mistake in the toolchain that leads to LTO information not
> > +being used (e.g. an older @code{libtool} calling @code{ld} directly).
> > +This is both an advantage, as the system is more robust, and a
> > +disadvantage, as the user is not informed that the optimization has
> > +been disabled.
>
> Well, such a disadvantage could be ameliorated with a warning, no?
>
> Rainer just mentioned other instances where LTO would silently not do
> TRT (nm in PATH with different format, etc), so it would seem generally
> useful to at least optionally warn.
I can't see how this is possible, or if it is, then how it is possible
to detect the legitimate case of using the fat binary w/o link time
optimization.
Richard.