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Bug 13689 as further evidence of my point about maintainers
- From: Daniel Berlin <dberlin at dberlin dot org>
- To: gcc at gcc dot gnu dot org list <gcc at gcc dot gnu dot org>
- Date: Wed, 14 Jan 2004 18:24:22 -0500
- Subject: Bug 13689 as further evidence of my point about maintainers
As further evidence of my point that maintainers should be trying to
speed up the code, rather than just fixing regressions, i'd like to
direct your attention to bug 13689.
This bug is interesting because it is a latent bug, with wrong-code
generation potential, that we only caught because of Honza
reimplementing alias sets for speed.
IOW, if Honza hadn't tried and succeeded in speeding up the compiler,
we wouldn't have seen this bug, but it would still be there.
It is *highly* unlikely we would have caught it with the splay tree
implementation (because of the lack of bounds checking/assertions that
values we expect to be in the tree were found in the tree) until it
actually generated wrong code, and it probably would have not been fun
to track down (it took 5 of us collaborating on IRC around someone's
debugger quite a while to figure this one out).
Speeding up the compiler through data structure changes and such
doesn't just make the compiler faster, it usually forces us to fix
latent bugs.
I'll close by also noting that this potential[1] wrong-code bug would
have been in the 3.4 release if we didn't allow this speedup to go in
during stage 3!
--Dan
[1] I only say potential because no wrong-code testcase exists for it,
though i'm sure one could create one through careful use of pch and
types