hg: valhalla/valhalla/langtools: Add support for tracking 'any'-related opcodes
forax at univ-mlv.fr
Mon Jul 28 23:09:08 UTC 2014
On 07/29/2014 01:02 AM, John Rose wrote:
> On Jul 28, 2014, at 3:09 PM, Remi Forax <forax at univ-mlv.fr
> <mailto:forax at univ-mlv.fr>> wrote:
>> I suppose that value types will not use several slots, otherwise if
>> you change a value type to add a field,
>> you will need to recompile all codes that use that value type.
>> So either the interpreter will treat value type as objects or it will
>> use a double indirection ?
>> (the stack will contains an index to a stack location inside the
>> current stack frame containing all the values of the value type).
> It would be unworkable to have values occupy a variable amount of
> interpreter (JVM state) space. The only reasonable choice is 1 slot,
> which means (yes) some amount of slop and/or extra indirections.
> It also means that we ought to consider deprecating and removing the
> double-slot pattern in a suitable version of the JVM.
yes, if you do local var slot renaming for value type when parsing the
you can use the same mechanism for double.
> — John
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