On Wed, Jul 19, 2023 at 01:36:23PM +0000, Richard Biener wrote:
> > If we have a match between at least one of the comparison operands and
> > op2/op3, I think having equivalency there is perhaps more important than
> > the canonicalization, but it would be nice not to break it even if there
> > is no match. So, perhaps force_reg only if there is a match?
> > force_reg (cmpmode, force_reg (cmpmode, x)) is equivalent to
> > force_reg (cmpmode, x), so perhaps:
> > {
> > if (rtx_equal_p (orig_op0, op2))
> > op2p = XEXP (comparison, 0) = force_reg (cmpmode, orig_op0);
> > if (rtx_equal_p (orig_op0, op3))
> > op3p = XEXP (comparison, 0)
> > = force_reg (cmpmode, XEXP (comparison, 0));
> > }
> > and similarly for the other body?
>
> I don't think we'll have op3 == op2 == orig_op0 because if
> op2 == op3 the
>
> /* If the two source operands are identical, that's just a move. */
>
> if (rtx_equal_p (op2, op3))
> {
> if (!target)
> target = gen_reg_rtx (mode);
>
> emit_move_insn (target, op3);
> return target;
>
> code should have triggered. So we should know we invoke force_reg
> only once for each comparison operand check?
>
> So I'm going to test the following ontop of the patch.
Please use else if instead of the second if then.
Ok with that change.
> --- a/gcc/optabs.cc
> +++ b/gcc/optabs.cc
> @@ -5131,11 +5131,10 @@ emit_conditional_move (rtx target, struct
> rtx_comparison comp,
> > COSTS_N_INSNS (1))
> && can_create_pseudo_p ())
> {
> - XEXP (comparison, 0) = force_reg (cmpmode, orig_op0);
> if (rtx_equal_p (orig_op0, op2))
> - op2p = XEXP (comparison, 0);
> + op2p = XEXP (comparison, 0) = force_reg (cmpmode,
> orig_op0);
> if (rtx_equal_p (orig_op0, op3))
> - op3p = XEXP (comparison, 0);
> + op3p = XEXP (comparison, 0) = force_reg (cmpmode,
> orig_op0);
> }
> if (CONSTANT_P (orig_op1) && optimize
> && (rtx_cost (orig_op1, mode, COMPARE, 0,
> @@ -5143,11 +5142,10 @@ emit_conditional_move (rtx target, struct
> rtx_comparison comp,
> > COSTS_N_INSNS (1))
> && can_create_pseudo_p ())
> {
> - XEXP (comparison, 1) = force_reg (cmpmode, orig_op1);
> if (rtx_equal_p (orig_op1, op2))
> - op2p = XEXP (comparison, 1);
> + op2p = XEXP (comparison, 1) = force_reg (cmpmode,
> orig_op1);
> if (rtx_equal_p (orig_op1, op3))
> - op3p = XEXP (comparison, 1);
> + op3p = XEXP (comparison, 1) = force_reg (cmpmode,
> orig_op1);
> }
> prepare_cmp_insn (XEXP (comparison, 0), XEXP (comparison, 1),
> GET_CODE (comparison), NULL_RTX, unsignedp,
Jakub
