On Tue, Nov 16, 2010 at 4:21 PM, Levente Uzonyi
<leves@elte.hu> wrote:
On Tue, 16 Nov 2010, Eliot Miranda wrote:
Um, on Cog it sends a message if the method containing the #= has been
jitted. But the issue is /not/ whether there is a send or not. The issue
But it couldn't before. You could only use it if the classes and ranges were just right. For example, #= isn't "atomic" for large integers, and the #= primitive will fail for large integers > 64 bits. In assuming #= is "atomic" for SmallInteger x Float you're relying on an optimization in the Interpreter. Look at the Blue book and you won't see this behaviour. Read the ANSI spec and you won't see this behaviour specified. So you're juts getting away with it on one particular implementation. (IMO)
Again IMO, you /can/ assume that SmallInteger>#= and Float>#= won't fail if their argument is of the same class as the receiver, but you can't assume that there won't be a send.
best
Eliot
Levente
is what the behaviour of the primitive code is. In the interpreter #= will
short-circuit (avoid the send) if both the receiver and the argument are
either a SmallInteger or a Float. In the JIT the primitive will not fail if
the receiver and argument are both SmallIntegers or Floats or if the
receiver is a Float and the argument is an Integer, but will fail if the
receiver is a SmallInteger and the argument is a Float.
snip