Ross Ridge wrote:
Robert Dewar write:
Usually there are ways of telling what is going on at a sufficiently
low level, but in any case, code using the conditional jump instruction
(jo/jno) is hugely better than what we do now (and it is often faster
to usea jo than into).
My point is that using INTO or some other processor's overlow mechanism
that requires operating system support wouldn't necessarily be better for
Ada, even it performs better (or uses less space) than the alternatives.
Having the program crash with a vague exception would meet the
requirements of -ftrapv, but not Ada.
But, once again, using the processor specific JO instruction will be
much better for Ada than double length arithmetic, using JO does not
involve a "program crash with a vague exception". Similarly, testing
the sticky overflow flag on Power is also quite reasonable.
Ross Ridge
