Re: [PATCH] lra: A multiple_sets is not a simple_move_p (PR73650)

[Jeff Law <law at redhat dot com>]

On 08/12/2016 12:38 PM, Segher Boessenkool wrote:
> Hi!
>
> In the PR we have a PARALLEL of a move and a compare (a "mr." instruction).
> The compare is dead, so single_set on it returns just the move.  Then,
> simple_move_p returns true; but the instruction does need reloads in this
> case.  This patch solves this by making simple_move_p return false for
> every multiple_sets instruction.
>
> Bootstrapped and regression checked on powerpc64-linux (-m64,-m32).
> Is this okay for trunk?
>
>
> Segher
>
>
> 2016-08-12  Segher Boessenkool  <segher@kernel.crashing.org>
>
> 	PR rtl-optimization/73650
> 	* lra-constraints.c (simple_move_p): If the insn is multiple_sets
> 	it is not a simple move.
OK.

Though I do wonder if it would be advantageous to try and rewrite such 
insns.

jeff