over-eager verification

Wed Mar 6 06:09:00 GMT 2002

Per Bothner writes:
 > Tom Tromey wrote:
 > >>>>>>"Per" == Per Bothner <per@bothner.com> writes:
 > > 
 > > Per> We should verify a method the first time it is invoked, not when
 > > Per> its class is prepared, since since most methods will never get
 > > Per> called.
 > > 
 > > I don't think we can do this. See JVM Spec Section 4.9.1, Pass 3:
 > > 
 > > Still during linking, the verifier checks the code array of the
 > > Code attribute for each method of the class file by performing
 > > data-flow analysis on each method.
 > > 
 > > So it explicitly requires checking during preparation and not at
 > > invocation.
 > 
 > Who cares? It's just a book. I know the guy who wrote it ...
 > 
 > We have to look at the big picture: Making sure that invalid code
 > does not violate the Virtual Machine constraints is the big picture.
Sure, but a Java program might need to prompt an operator immediately
when an invalid class is loaded rather than a few weeks later in the
middle of the night when the operator is asleep.
Andrew.