Null pointer check elimination

Mon Nov 14 21:27:00 GMT 2005

Gabriel Dos Reis wrote:
> "Michael N. Moran" <mike@mnmoran.org> writes:
> | Wow. I'm sure there is sound reasoning for this ... but I can't
> | understand what that might be given a client module could intentionally
> | (if ill-adviseadly) simply invoke the function:
>> then it gets what it deserves. Check out GCC manual for null-pointer
> check.

 From info gcc:
`-fdelete-null-pointer-checks'
 Use global dataflow analysis to identify and eliminate useless
 checks for null pointers. The compiler assumes that dereferencing
 a null pointer would have halted the program. If a pointer is
 checked after it has already been dereferenced, it cannot be null.
The second sentence makes me question the difference between an
actual dereferencing operation and the use of a dereferencing
operator used to convert a pointer to a C++ reference. Clearly
(to me anyway ;-) the conversion case does not actually cause
an access to the object.
-- 
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