Coming back to this just in time for it not to be three months later,
sorry...
I still think it would be better to consolidate ifcvt a bit more,
rather than effectively duplicate bits of cond_move_process_if_block
in noce_convert_multiple_sets. But perhaps it was a historical
mistake to have two separate routines in the first place, and I guess
making noce_convert_multiple_sets handle more cases might allow us
to get rid of cond_move_process_if_block at some point. So let's
go ahead with this anyway.
Robin Dapp <rd...@linux.ibm.com> writes:
> This patch checks allows immediate then/else operands for cmovs.
> We rely on,emit_conditional_move returning NULL if something unsupported
> was generated.
>
> Also, minor refactoring is performed.
>
> --
>
> gcc/ChangeLog:
>
> 2018-11-14 Robin Dapp <rd...@linux.ibm.com>
>
> * ifcvt.c (have_const_cmov): New function.
> (noce_convert_multiple_sets): Allow constants if supported.
> (bb_ok_for_noce_convert_multiple_sets): Likewise.
> (check_cond_move_block): Refactor.
> ---
> gcc/ifcvt.c | 21 +++++++++++----------
> 1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
> index 55205cac153..99716e5f63c 100644
> --- a/gcc/ifcvt.c
> +++ b/gcc/ifcvt.c
> @@ -3214,7 +3214,9 @@ noce_convert_multiple_sets (struct noce_if_info
> *if_info)
> we'll end up trying to emit r4:HI = cond ? (r1:SI) : (r3:HI).
> Wrap the two cmove operands into subregs if appropriate to prevent
> that. */
> - if (GET_MODE (new_val) != GET_MODE (temp))
> +
> + if (!CONST_INT_P (new_val)
> + && GET_MODE (new_val) != GET_MODE (temp))
> {
> machine_mode src_mode = GET_MODE (new_val);
> machine_mode dst_mode = GET_MODE (temp);
> @@ -3225,7 +3227,8 @@ noce_convert_multiple_sets (struct noce_if_info
> *if_info)
> }
> new_val = lowpart_subreg (dst_mode, new_val, src_mode);
> }
> - if (GET_MODE (old_val) != GET_MODE (temp))
> + if (!CONST_INT_P (old_val)
> + && GET_MODE (old_val) != GET_MODE (temp))
> {
> machine_mode src_mode = GET_MODE (old_val);
> machine_mode dst_mode = GET_MODE (temp);
> @@ -3362,9 +3365,9 @@ bb_ok_for_noce_convert_multiple_sets (basic_block
> test_bb, unsigned *cost)
> if (!REG_P (dest))
> return false;
>
> - if (!(REG_P (src)
> - || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
> - && subreg_lowpart_p (src))))
> + if (!((REG_P (src) || (CONST_INT_P (src)))
> + || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
> + && subreg_lowpart_p (src))))
> return false;
>
> /* Destination must be appropriate for a conditional write. */
CONSTANT_P (as for check_cond_move_block) would cover more cases than
CONST_INT_P. No need for brackets around CONST_INT_P (...).
I was tempted to say we should use register_operand too, but I guess
that allows unwanted (subreg (mem...))s (as if there's any other kind).
> @@ -3724,7 +3727,7 @@ check_cond_move_block (basic_block bb,
> {
> rtx set, dest, src;
>
> - if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
> + if (!active_insn_p (insn))
> continue;
> set = single_set (insn);
> if (!set)
I assume this is to skip notes, but shouldn't this still include JUMP_P?
It also looks like it should be an independent patch.
> @@ -3740,10 +3743,8 @@ check_cond_move_block (basic_block bb,
> if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
> return FALSE;
>
> - if (side_effects_p (src) || side_effects_p (dest))
> - return FALSE;
> -
> - if (may_trap_p (src) || may_trap_p (dest))
> + /* Check for side effects and trapping. */
> + if (!noce_operand_ok (src) || !noce_operand_ok (dest))
> return FALSE;
>
> /* Don't try to handle this if the source register was
Seems wrong to use something called noce_operand_ok in a routine
that is explicitly handling cases in which conditional execution
is possible.
More importantly, I can't see anywhere that handles the MEM_P case
specially for cond_move_*, so are you sure this is really safe?
Might be better to leave it as-is if this part is just a clean-up.
Thanks,
Richard
