Paul Schlie wrote:
From: Robert Dewar <[EMAIL PROTECTED]>
You keep saying this over and over, but it does not make it true. Once
again, the whole idea of making certain constructs undefined, is to
ensure that efficient code can be generated for well defined constructs.
- Can you give an example of an operation which may yield an undefined
non-deterministic result which is reliably useful for anything?
The simplest example is a shift operation, x << n, where the compiler
may assume that the shift count is smaller than the width of the type.
All sane machines agree on shift behaviour for 0 <= n < width, but there
are differences between machines for n >= width. Since this case is
undefined by the language, it is ensured that shifts take only a single
instruction on essentially all machines.
Bernd
