> --- a/gcc/doc/md.texi
> +++ b/gcc/doc/md.texi
> @@ -4720,6 +4720,17 @@ Add operand 2 and operand 1, storing the result in
> operand 0. All operands must have mode @var{m}. This can be used even on
> two-address machines, by means of constraints requiring operands 1 and 0 to
> be the same location.
>
> +@cindex @code{addptr@var{m}3} instruction pattern
> +@item @samp{addptr@var{m}3}
> +Like @code{addptr@var{m}3} but does never clobber the condition code.
> +It only needs to be defined if @code{add@var{m}3} either sets the
> +condition code or address calculations cannot be performed with the
> +normal add instructions due to other reasons. If adds used for
> +address calculations and normal adds are not compatible it is required
> +to expand a distinct pattern (e.g. using an unspec). The pattern is
> +used by LRA to emit address calculations. @code{add@var{m}3} is used
> +if @code{addptr@var{m}3} is not defined.
I'm a bit skeptical of the "address calculations cannot be performed with the
normal add instructions due to other reasons" part". Surely they can be
performed on all architectures supported by GCC as of this writing, otherwise
how would the compiler even work? And if it's really like @code{add@var{m}3},
why restricting it to addresses, i.e. why calling it @code{addptr@var{m}3}?
Does that come from an implementation constraint on s390 that supports it only
for a subset of the cases supported by @code{add@var{m}3}?
> diff --git a/gcc/lra.c b/gcc/lra.c
> index 77074e2..e5e81474 100644
> --- a/gcc/lra.c
> +++ b/gcc/lra.c
> @@ -254,6 +254,19 @@ emit_add3_insn (rtx x, rtx y, rtx z)
> rtx insn, last;
>
> last = get_last_insn ();
> +
> + if (have_addptr3_insn (x, y, z))
> + {
> + insn = gen_addptr3_insn (x, y, z);
> +
> + /* If the target provides an "addptr" pattern it hopefully does
> + for a reason. So falling back to the normal add would be
> + a bug. */
> + lra_assert (insn != NULL_RTX);
> + emit_insn (insn);
> + return insn;
> + }
> +
> insn = emit_insn (gen_rtx_SET (VOIDmode, x,
> gen_rtx_PLUS (GET_MODE (y), y, z)));
> if (recog_memoized (insn) < 0)
Same ambiguity here, emit_add3_insn is not documented as being restricted to
addresses:
/* Emit insn x = y + z. Return NULL if we failed to do it.
Otherwise, return the insn. We don't use gen_add3_insn as it might
clobber CC. */
static rtx
emit_add3_insn (rtx x, rtx y, rtx z)
--
Eric Botcazou
