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Re: Draft "Unsafe fp optimizations" project description.
- To: gcc at gcc dot gnu dot org, ross dot s at ihug dot co dot nz
- Subject: Re: Draft "Unsafe fp optimizations" project description.
- From: dewar at gnat dot com
- Date: Sun, 5 Aug 2001 08:32:50 -0400 (EDT)
<<I think what Toon meant was something like: if you throw all the
possible distinct values for a given FP representation into a sack, and
pick the operands at random from the sack, there's roughly a 50/50
chance that B*C will overflow or underflow.
I agree that's what he meant, but that is entirely wrong, the proportion
of numbers that overflow is far far smaller. Remember we are talking about
floating-point values here, not real values. There are as many fpt
numbers with an exponent of 1 as there are with an exponent of 100 :-)