Re: Why have two RETURN opcode for function

[Scott Morgan <blumf@...>]

On 21/03/16 21:07, René Rebe wrote:
> On Mar 21, 2016, at 17:12, Coda Highland <chighland@gmail.com> wrote:
>> On Mon, Mar 21, 2016 at 9:10 AM, Scott Morgan <blumf@blueyonder.co.uk> wrote:
>>> On 21/03/16 15:59, Dirk Laurie wrote:
>>>> 2016-03-21 16:32 GMT+02:00 Wangbo <wangbo.red@gmail.com>:
>>>>> I have simple Lua code, why have two RETURN opcode for foo function after i
>>>>> check compile code.
>>>>>
>>>>> 6 [4] RETURN   1 2
>>>>> 7 [5] RETURN   0 1
>>>>
>>>> Checking all code paths to make sure that the `end` statement
>>>> cannot be reached would make the compiler more complicated.
>>>
>>> Is this an overhead of supporting gotos?
>>
>> Considering this is bytecode and everything from loops to conditionals
>> are implemented as jumps? You could say that. But it's not
>> specifically tied to the "goto" language feature; it would still be
>> relevant even if you couldn't use "goto" in Lua code.
> 
> IIRC older Lua versions indeed already simply did this too.
> At least I remember seeing this in 5.1 which did not yet had gotos, …

Interesting. In what situations (i.e. what kind of source code) does
this become an issue that the extra return is needed? Error handling?

Scott