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Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
- From: Paul Eggert <eggert at CS dot UCLA dot EDU>
- To: gcc at gcc dot gnu dot org, autoconf-patches at gnu dot org, bug-gnulib at gnu dot org
- Date: Sun, 31 Dec 2006 17:32:40 -0800
- Subject: Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
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Robert Dewar <email@example.com> writes:
> We have not seen ONE imaginary example, let
> alone a real example, where the optimziation of loop invariants
> (by far the most important optimization in the class we are
> discussing) would break existing code.
But didn't this thread get started by a real program that was broken
by an optimization of loop invariants? Certainly I got a real bug
report of a real problem, which you can see here:
Here is a bit more discussion:
If this doesn't count as "optimization of loop invariants"
then what would count?
This particular example was just a test program run by "configure", so
the penalty for getting it wrong wasn't that severe -- the application
compiled its own version of mktime rather than using the system
mktime. But I daresay I can find an example of real-world production
code that does something similar.