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Re: Ada front-end depends on signed overflow
Eric Botcazou wrote:
Once again, have you actually examined how awtul the code we
generate now is?
Yes, I have. Indeed not pretty, but suppose that we managed to cut the
overhead in half, would that make -gnato really more attractive?
Yes, it would definitely make the difference, given the figures
we have seen.
From that, we have 2 alternatives: synchronous or asynchronous exceptions.
The current implementation is synchronous, as we explicitly raise exceptions
in the code by calling a routine. I guess you're pushing for asynchronous
exceptions since this is probably the only efficient approach, i.e. we rely
on the hardware to trap and try to recover from that.
Defintiely not, integer overflow generates async traps on very few
architectures. Certainly synchronous traps can be generated (e.g.
with into on the x86).