http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60607
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |x86_64-*-*, i?86-*-*
Status|UNCONFIRMED |NEW
Keywords| |lto
Last reconfirmed| |2014-03-21
Component|lto |target
Ever confirmed|0 |1
Summary|Missing lto command line |-march=native command line
|option handling causes |option handling breaks LTO
|build failures |option machinery
Severity|enhancement |normal
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The issue is that -march=native "explodes" to explicit set options, including
negative ones such as -mno-sse4.1. That's bad, as we now have conflicting
options for bar.o and foo.o which we merge like
/* Do what the old LTO code did - collect exactly one option
setting per OPT code, we pick the first we encounter.
??? This doesn't make too much sense, but when it doesn't
then we should complain. */
I think this option exploding done by -march=native is simply broken.
At least exploding to full positive _and_ negative lists is. Either we
have a separate option for each target feature - then we don't need the
-mno-xxx stuff, or we don't - then we need to fix that.
Note that the plan for the future is to no longer "merge" any target options
for link-time but use target attributes more aggressively. The current code
merely tries to make the link-step succeed somehow, not follow what the
user intended with setting specific target options on specific TUs.
