On Aug 25, 2011, at 11:23 PM, Jeroen Frijters wrote:
> I was surprised by this as well (from an implementers point of view), because
> the use of asType is an implementation detail. Normally when you call a
> method taking a boolean/byte/short/char you also load an int onto the stack,
> so why would this case be any different?
When you call a function of type, say, (B), you are promising that the 32-bit
int you loaded onto the stack fits into the declared subrange, say, -128..127.
(This is a little-known invariant of the verifier. Although all primitive
arguments and return values are passed in 32 and 64 bit containers, some of the
32-bit values are required/guaranteed to be constrained to a subrange of
values.)
So if you start with an arbitrary int value (as an ldc produces) you need an
extra dynamic operation to force the value into the required subrange.
-- John
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