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Re: [m68k]: convert mode 5 addressing w/zero offset into mode2
Andreas Schwab <schwab@suse.de> writes:
> Ian Lance Taylor <ian@wasabisystems.com> writes:
>
> > Peter Barada <peter@the-baradas.com> writes:
> >
> >> This following patch converts:
> >>
> >> <op> 0(%Ay),%Rx
> >> <op> %Ry,0(%Ax)
> >> <op> 0(%Ay),0(%Ax)
> >>
> >> into:
> >>
> >> <op> (%Ay),%Rx
> >> <op> %Ry,(%Ax)
> >> <op> (%Ay),(%Ax)
> >>
> >> To reduce the size of the instruction by the word used to hold the
> >> offset.
> >
> > This kind of patch makes me nervous. Sometimes people write assembler
> > code with the full intention of generating a specific addressing mode,
> > even if it is apparently less efficient. I'm not sure it is
> > appropriate for the assembler to second-guess the programmer in a case
> > like this.
>
> I had the same concern, but you can disable this optimization by writing
> 0:w instead of 0. This is in par with other kinds of optimizations that
> only happen when using unspecified size operands.
OK, I withdraw my objection.
Ian