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[Bug lto/52178] [4.7 regression] Ada bootstrap failure in LTO mode
- From: "ebotcazou at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 13 Feb 2012 11:53:38 +0000
- Subject: [Bug lto/52178] [4.7 regression] Ada bootstrap failure in LTO mode
- Auto-submitted: auto-generated
- References: <bug-52178-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52178
--- Comment #4 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-02-13 11:53:38 UTC ---
> Merging happens at WPA time, it happens again at LTRANS but that is an
> implementation artifact (it should not be necessary to merge again).
OK.
> Ok, this sounds like it is a real bug, especially if the existing machinery
> to plug these holes does not trigger (and issue the warning).
Something I remarked while trying to debug this: "regular" type merging has a
sophisticated machinery taking into account SCCs (gtc_visit) while "canonical"
type merging doesn't have it. The hypothesis I came up with is that the former
was able to merge the various instances of the type whereas the latter wasn't.
Since the middle-end type system is based on canonical types, it chokes.
> So - do you by chance happen to have a (small) testcase? ;)
No, but I can try to distill one