From: Andrew Cagney <cagney@redhat.com>
To: Phil Muldoon <pmuldoon@redhat.com>
Cc: Frysk Hackers <frysk@sourceware.org>
Subject: Re: ISA checks for factories
Date: Wed, 03 Oct 2007 19:43:00 -0000 [thread overview]
Message-ID: <4703F084.8050301@redhat.com> (raw)
In-Reply-To: <4703549C.30709@redhat.com>
Phil,
unfortunate timing, we crossed e-mails during the night,
Phil Muldoon wrote:
> I've written several factories to decide what class to instantiate
> depending on the ISA. These usually end up as hacks, probably because
> I do not understand something quite right, or there is no real decent
> "What ISA does this task/proc belong" discovery.
>
> I can instance check an ISA with:
>
> Isa isa = proc.getIsa();
There is now also:
ISA isa = task.getISA()
which returns a frysk.isa.ISA, which looks smells and behaves like an
ENUM. This new ISA just the following attributes:
- family (i386, x8664, PPC)
- word size (4, 8)
- byte order (little, big)
leading to the combinations: IA32, X8664, PPC32LE, PPC32BE, PPC64LE,
PPC64BE.
> if (isa instanceof IsaIA32) ....
It can then be used as either:
if (isa == ISA.IA32)
..
else if (isa = ISA.X8664)
..
or better?:
ISAMap map = new ISAMap("why am I here")
.put(ISA.IA32, new My(IA32))
.put(ISA.X8664, new My(X8664))
;
...
// Throws a RuntimeException if ISA missing
My o = (My) map.get(task.getISA);
which could easily be wrapped up in a factory.
Andrew
>
> and so on, but that will not work for 32 on 64 ISAs. For example, on a
> 32 bit process on a 64 bit system, the instance returned would be
>
> LinuxIa32On64
>
> And those cannot be instance checked as they are package private,
> while the "native" ISAs are public.
>
> So what is the solution here? Open the scope of the xxOnxx ISAs? I get
> the feeling that instanceof checks tell me that we need to work on a
> better solution anyway. Reverting to reflection screams hack to me.
>
> Regards
>
> Phil
next prev parent reply other threads:[~2007-10-03 19:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-03 8:36 Phil Muldoon
2007-10-03 19:43 ` Andrew Cagney [this message]
2007-10-09 7:53 ` Phil Muldoon
2007-10-09 9:16 ` Phil Muldoon
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