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- Subject: Re: Debug hook not called on "local" lines in some cases
- From: liam mail <liam.list@...>
- Date: Wed, 30 Jan 2013 22:10:33 +0000
On 30 January 2013 21:33, Paul K <firstname.lastname@example.org> wrote:
> Is this a feature or a bug?
This is a feature. Lets just look at one implementation 5.2 for now.
c = 1
Produces only there instructions one of which is the default return.
The first two being OP_LOADNIL which assigns nil to the first four
stack slots and the OP_LOADK which assigns the constant to slot 2(zero
local b = 1 --<-- added assignment
c = 1
This will have five instructions, OP_LOADNIL to the first slot(a),
OP_LOADK to the second slot(b), OP_LOADNIL to load nil to the third
and four slots (c and d), OP_LOADK loading the constant into slot 2(c)
and the final OP_RETURN.
Now 5.1 bytecode is slightly different in that the OP_LOADK's are
optimised out for locals at the beginning of a scope so the first
snippet I have show will only have two instructions; one to load a
constant and the default return.
So it is a mixture of an optimisations and OP_LOADNIL loading values
to more than one slot.