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Re: Live range splitting in new allocator

On Jan 30, 2001, Joe Buck <> wrote:

> Marc Espie writes:
>> I don't know how hard it would be to do, but I feel that it would make
>> a lot of sense to make *sure* the uninitialized variables are set to
>> something completely different from 0 in -O0 mode. After all, we already
>> know that -O0 code is bad, performance-wise, why not take the plunge and
>> initialize variables to bad defaults so that stuff *will* crash at -O0 as
>> well ?

> For floating point on IEEE platforms, it's easy enough: use a NaN.
> However, for variables that are used as boolean values (whether a C++ bool
> or a C int used as a flag), you'll make things more deterministic than
> before: an uninitialized Boolean auto variable used to be random, under your
> proposal it will always be true.

How about using some bit in the return value of random() instead? :-)

Alexandre Oliva   Enjoy Guarana', see
Red Hat GCC Developer                  aoliva@{,}
CS PhD student at IC-Unicamp        oliva@{,}
Free Software Evangelist    *Please* write to mailing lists, not to me

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