optimization for function call without paremters

I think this optimization could be done by two approach:

1. Add another FCALL op, which init a function call and call that function
   directly for functions without parameters.

2. Let the original INIT_FCALL support "call function when the number of
   parameter == 0"

Hi Dmitry,

I found that INIT_FCALL doesn't use opline->result.var and DO_ICALL
doesn't use op1 or op2. The original purpose of separating these two op was
for sending parameters.

However, if a function doesn't need parameters and it's an internal
function, I think the operation could be merged into INIT_FCALL.

So I guess we can do this below to reduce one bytecode for each function
call without parameters:

if (opline->extended_value == 0) {
     // call the function directly and store the value in the result.
}

Your thoughts?

Best Regards,

Yo-An Lin

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Best Regards,

Yo-An Lin