[fooker]

> The compiler may also flatten a loop.

http://c2.com/cgi/wiki?SufficientlySmartCompiler

In practice, C compilers are still notoriously bad at loop optimizations.

Polyhedral optimizations provided some hope, but no compiler managed to adopt it in production.

[uecker]

Maybe, but also irrelevant to the discussion because whether you write mat[b * A + a] by hand or mat[b][a] and let the compiler frontend expand then makes no difference to the optimizer.

[fooker]

You missed the point.

Those two representations are equivalent, yes. But that's not what flattening loops mean.

[uecker]

You are telling me what my point was?