Re: Lua 5.2 OP_LOADNIL instruction

[liam mail <liam.list@...>]

On 20 October 2011 21:51, liam mail <liam.list@googlemail.com> wrote:
> I was wondering why Lua 5.2 does not preform the same optimisation for
> bytecode which 5.1 did when a there is not an operation before an
> OP_LOADNIL, for 5.1 the generator would remove the load nil
> instructions. For example a simple file which just contains a local
> which will be set to nil:
> $ cat ./op_loadnil.lua
> local a
>
> For 5.1 produces the following:
> $ luac -l ./op_loadnil.lua
> main <./op_loadnil.lua:0,0> (1 instruction, 4 bytes at 0x100101050)
> 0+ params, 2 slots, 0 upvalues, 1 local, 0 constants, 0 functions
>        1       [1]     RETURN          0 1
>
> Yet for 5.2 it leaves in the instruction:
> $ ./luac -l ./op_loadnil.lua
> main <./op_loadnil.lua:0,0> (2 instructions at 0x100100ee0)
> 0+ params, 2 slots, 1 upvalue, 1 local, 0 constants, 0 functions
>        1       [1]     LOADNIL         0 0
>        2       [1]     RETURN          0 1
>
> Would someone please shine some light on this and any implications
> that may follow it.
>
> Thanks.
> Liam
>

Bump