On Sun, Jan 6, 2013 at 8:47 PM, Alexandre Oliva <aol...@redhat.com> wrote: > On Jan 2, 2013, Richard Biener <richard.guent...@gmail.com> wrote: > >> On Sun, Dec 30, 2012 at 1:22 AM, Alexandre Oliva <aol...@redhat.com> wrote: >>> On Dec 21, 2012, Richard Biener <richard.guent...@gmail.com> wrote: >>> >>>> On Fri, Dec 21, 2012 at 6:33 AM, Alexandre Oliva <aol...@redhat.com> wrote: >>>>> libmudflap emits a global initializer that registers memory ranges for >>>>> global data symbols. However, even if IPA decides not to emit a symbol >>>>> because it's unused, we'd still emit registration sequences for them in >>>>> some cases, which, in the PR testcase, would result in TOC references to >>>>> the undefined symbols. >>> >>>> Hmm, I think that at this point of the compilation you are looking for >>>> TREE_ASM_WRITTEN instead. >>> >>> That doesn't work, several mudflap regressions show up because accesses >>> to global library symbols that are accessed by template methods compiled >>> with mudflap (say cout) are then verified but not registered. We have >>> to register symbols that are not emitted but that referenced. > >> Ehm, how can something be not emitted but still referenced? You mean if >> it's external? > > Yeah. > >> if (!TREE_ASM_WRITTEN (obj) || DECL_EXTERNAL (obj)) > >> instead? > > Then we're back to the original bug. > > How does the test above tell whether we're actually referencing the > object? Only when we are do we want to register it with mudflap. If > it's referenced and we don't register it, we get mudflap runtime errors. > If it's not referenced but we register it, we get link-time errors if > the symbol is one we'd have emitted if it was referenced.
Then the bug is that we register something but do not actually tell the middle-end that this is a reference. Hmm. I suppose instead of asking for TREE_ASM_WRITTEN you may want to look at DECL_RTL (which should be set for all referenced decls, whether external or not). Richard. > -- > Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/ > You must be the change you wish to see in the world. -- Gandhi > Be Free! -- http://FSFLA.org/ FSF Latin America board member > Free Software Evangelist Red Hat Brazil Compiler Engineer
