Re: question on MIPS: addiu


"Harold Aptroot" <harold.aptroot@xxxxxxxxx> wrote in message
news:11451$48b85b21$53558f0b$19693@xxxxxxxxxxxxxxxxxxxxxxxxxx
"Keep Asking" <ask8y@xxxxxxxxx> wrote:
On Aug 29, 2:32 am, Herbert Kleebauer <k...@xxxxxxxxx> wrote:

<snip>


I eman
addiu v1, v1, 0
I know what it means "addiu", I just do not understand what is purpose
to do? it does not seems to do anything.

It takes some time at least

yes.

think of it this way:
i=i+0;


now, it seems functionally equivalent to a nop, much like how in x86 'xchg
eax, eax' serves this same purpose (in fact, it IS the official nop, with
the nop opcode name simply being an alias, except of course for the
multi-byte nop forms).


now, this does lead to another issue:
on x86 at least, there is not a 1:1 conversion between input code and
opcodes, leading to the result that disassemblers may in many cases give
different (if still functionally equivalent) results for disassembly than
were used during assembly...

it is also further possible that reassembly not lead to exactly the same
sequence of bytes either, which could in some cases make the code no longer
functionally equivalent (or at least in principle).

or such...



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