[Bug middle-end/36902] Array bound warning with dead code after optimization

[manu at gcc dot gnu dot org]

------- Comment #21 from manu at gcc dot gnu dot org  2008-08-22 17:54 -------
(In reply to comment #19)
> (In reply to comment #18)
> > I think that if the compiler knows that the code is never executed then, we
> > shouldn't warn. 
> 
> It does but only later on in the optimization it knows that the code is dead.

My point is that if I understand the vrp code correctly, we can detect that the
code is dead before warning. In this case, the code is detected dead within
VRP, not in a later pass. Maybe I am wrong. Let's see what Mueller and Guenther
have to say. In any case, we should consider whether warning in conditional BBs
is a good idea at all. I think that saying 

"array subscript *is* above array bounds"

in a BB that is executed conditionally is not a good idea in general.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36902