hg: valhalla/valhalla/langtools: Add support for tracking 'any'-related opcodes

Remi Forax forax at univ-mlv.fr
Tue Jul 29 00:30:03 UTC 2014


On 07/29/2014 01:26 AM, John Rose wrote:
> On Jul 28, 2014, at 4:09 PM, Remi Forax <forax at univ-mlv.fr 
> <mailto:forax at univ-mlv.fr>> wrote:
>
>> yes, if you do local var slot renaming for value type when parsing 
>> the bytecode,
>> you can use the same mechanism for double.
>
> Here is a concrete suggestion, to get rid of double slots completely 
> in the setting of value types:
>
> Deprecate and remove [ld][a]?load* and [ld][a]?store* opcodes.
>
> In generated bytecodes, replace them by the corresponding v* opcodes 
> (which would apply to long and double primitive values, as well as 
> non-primitive, non-reference values).
>
> A few other opcodes (d2i, etc.) are kept as-is, but the slot-pair 
> semantics are removed for them also.
>
> Later, repurpose those opcode points for other things.  (This will 
> free the d* or l* series of instructions for later use.)
>
> For compatibility, old class file versions would continue to use 
> slot-pairs (and will not recognize v* bytecodes).
> New class file versions would refuse (at least some of) the [dl]* 
> bytecodes.
>
> — John

I like this, it will make the specialization far easier :)

Rémi



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