[LLVMdev] Bug in LEA16r (X86InstrArithmetic.td) ??

[Tim Northover]

Hi Jun,

On 24 June 2014 08:08, Jun Koi <junkoi2004 at gmail.com> wrote:
> def LEA16r   : I<0x8D, MRMSrcMem,
>                  (outs GR16:$dst), (ins i32mem:$src),
>                  "lea{w}\t{$src|$dst}, {$dst|$src}", [], IIC_LEA_16>,
> OpSize16;
>
>
> Please correct me if I am wrong, but I think "ins i32mem" should be "ins
> i16mem" because this is about 16bit register?

I think there's something going on here, but it's probably more
complicated than that. The lea instruction just calculates an address,
so the resulting pointer doesn't really *have* a size.

Binutils seems to handle this reasonably by omitting the "dword
ptr"/"word ptr" part entirely when printing: "lea ax, [eax]" instead
of "mov ax, word ptr [eax]". The assembler accepts all variants, which
may or may not be a good choice.

Cheers.

Tim.