On Mon, May 17, 2010 at 2:27 PM, Diego Novillo <dnovi...@google.com> wrote: > On 5/16/10 23:18 , Jack Howarth wrote: >> What is the current LTO design with regards to the >> retention of compiler flags during the actual link >> time optimization compilation steps. For example, if > > Some options are embedded, but not all (see lto-opts.c). You will need > to pass the same flags to the compile and link commands. The options > that are saved are reapplied at link-time, but no merging is done (the > options taken from the first file in the link command are used).
That's not really true - they are sort-of merged. But also only literally passed options do count, so option pre-/post-processing done by the frontends are disregarded if not replicated by the lto frontend. Instead of trying to record switches that way we should instead save the final settings of relevant flag_* values somewhere and simply complain on mismatches. Richard.
