On Nov 5, 2008, at 6:12 PM, Zhongxing Xu wrote:
On Thu, Nov 6, 2008 at 9:33 AM, Ted Kremenek <[EMAIL PROTECTED]>
wrote:
On Nov 5, 2008, at 5:24 PM, Zhongxing Xu wrote:
Thoughts?
Ted
Sounds reasonable! I remember that there was RegionExtent code.
Maybe we should pick it up.
Right; I scribbled some code for that, but never really implemented
anything real. I think we just need to establish a "taxonomy" of
extents/sizes, and decide if we need a variant like RegionExtent or
can just use SVals.
I think we can use SVals for now and extend to a RegionExtent class
when necessary.
Another thing to discuss: what units shall we choose for
representing extent? In bits, bytes, or element numbers? For array
bounds checking, element numbers are the most direct. What other
clients care about the extents?
Bits, bytes, number of elements... these are each different
abstractions of memory, and different clients will have separate
needs. If we provide a clean interface to go between these units
(which could potentially be provided by a RegionExtent class) then I
think we (a) can serve more clients more easily and (b) have extra
error checking for cases when clients use the wrong units.
Here's one argument for bits. That's what ASTContext::getTypeSize()
and ASTContext::getTypeAlign() return (so there is some consistency
there). Moreover, it is plausible that we have regions over
individual bits (e.g., bit fields, bit-level typing). As long as its
consistent I think we're fine._______________________________________________
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