Suspicous code in kdelibs-3.5.2

[Stefan Teleman]

On Wednesday 05 April 2006 13:57, Aaron J. Seigo wrote:
> > The C++ standard does not say anything about arrays of arrays
> > being in contiguous memory, so this is not a false positive.
>
> what platforms/compilers do we support where this isn't the case?

If the Standard does not require multidimensional arrays to be in 
contiguous memory [1], an optimizing compiler on NUMA platforms can 
do whatever it wants when allocating multidimensional arrays. 

--Stefan

[1] ISO/IEC:14882:2003:8.3.4.9 states:

"[ Note: it follows from all this that arrays in C++ are stored 
row-wise (last subscript varies fastest) and that the first subscript 
in the declaration helps determine the amount of storage consumed by 
an array but plays no other part in subscript calculations. ]"

The implication of this paragraph seems to be that, for a 
multidimensional array declared as

T X[x][y]

an expression of type

X[x+n][y+n]

may point to an invalid address, given that the compiler is not 
required to calculate this address as an offset of the first 
subscript.

-- 
Stefan Teleman          'Nobody Expects the Spanish Inquisition'
steleman at nyc.rr.com                          -Monty Python