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

Remi Forax forax at univ-mlv.fr
Tue Jul 29 00:28:12 UTC 2014

On 07/29/2014 02:20 AM, John Rose wrote:
> On Jul 28, 2014, at 4:40 PM, Maurizio Cimadamore 
> <maurizio.cimadamore at oracle.com 
> <mailto:maurizio.cimadamore at oracle.com>> wrote:
>> This looks promising - are you envisioning some kind of 'inference' 
>> in the VM in order to figure out the 'width' of the v* opcodes? That 
>> might be non-trivial as it would probably mean propagate type info 
>> from the local var table attribute? An alternative perhaps could be 
>> to accept an extra operand containing the 'width' (i.e. 1 for int, 2 
>> for double/long, n for value types).
> Which opcode would have an ambiguous input?  Can't you always tell 
> whether it is I, J, or some specific value type?
> ...Or any other type:  Seems to me that, for correctness, we only need 
> v* and none of the [ailfd]*, if we do very simple forward-only 
> inference, like that supported by FrameMaps already.
> — John



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