possible gcse failure: not able to eliminate redundant loads

[Toon Moene]

Richard Henderson wrote:

> On Fri, Dec 13, 2002 at 09:25:54PM +0100, Toon Moene wrote:

>>I cannot imagine a valid Fortran program that contains an access to
>>memory that "might trap".

> Yeah, I guess there's really no concept of a null pointer is there...

Well, certainly not in the language that g77 compiles (a superset of 
Fortran 77), because there is no concept of "pointer" in that language.

However, Fortran 90/95 *do* have pointers, but also there it's not 
legally possible to "dereference" (to use the C-term) pointers that 
point to storage that has not been "defined" (given a value) - to say 
nothing of to point to something that isn't there (i.e., a pointer that 
hasn't been initialised to point to an existing object).

BTW, I wasn't aware it's legal to dereference NULL C pointers.

-- 
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
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