Re: PATCH: Remove InvMem from MMX/SSE instructions

["H. J. Lu" <hjl at lucon dot org>]

On Sun, Jul 16, 2006 at 01:23:56PM +0930, Alan Modra wrote:
> On Thu, Jul 13, 2006 at 04:09:03PM -0700, H. J. Lu wrote:
> > http://sourceware.org/ml/binutils/2001-05/msg00065.html
> > http://sourceware.org/ml/binutils/2001-05/msg00187.html
> > 
> > use InvMem on source operand to indicate that it must be register. 
> > I don't believe it is correct since RegYYY won't match memory anyway
> > and InvMem is used to indicate how operand should be encoded. This
> > patch removes it.
> 
> It's true that the way the code is currently written that removing this
> flag will not change the insn encoding.  All InvMem does on *source*
> operands of these reg->reg insns is document that the register is
> encoded in the regmem field of the modrm byte.  So why do you want to
> remove documentation?  There is certainly nothing wrong with InvMem on
> these operands.

Those operands only take registers and are encoded properly. What
additional information does InvMem provide here?

I am trying to clean up the usage of InvMem. The commennt says:

  /* InvMem is for instructions with a modrm byte that only allow a
     general register encoding in the i.tm.mode and i.tm.regmem fields,
     eg. control reg moves.  They really ought to support a memory form,
     but don't, so we add an InvMem flag to the register operand to
     indicate that it should be encoded in the i.tm.regmem field.  */
#define InvMem      0x80000000

However, there are

{"sldt",   1, 0x0f00, 0, Cpu286, wlq_Suf|Modrm,         { WordReg|InvMem, 0, 0} },
{"smsw",   1, 0x0f01, 4, Cpu286, wlq_Suf|Modrm,         { WordReg|InvMem, 0, 0} },
{"str",    1, 0x0f00, 1, Cpu286, wlq_Suf|Modrm,         { WordReg|InvMem, 0, 0} },

Those instructions take memory operand. InvMem seems to be used for something
else.


H.J.