Re: [PATCH 3/6] microblaze: Fixes for RTL checking

[Michael Eager <eager@eagerm.com>]

On 02/21/2017 06:48 AM, Segher Boessenkool wrote:
> REGNO can only be called on REGs, not SUBREGs; and INTVAL does not work
> on REGs.
>
> 2017-02-21  Segher Boessenkool  <segher@kernel.crashing.org>
>
> 	* config/microblaze/microblaze.c (microblaze_expand_shift): Do not
> 	test for register moves to themselves.
> 	* config/microblaze/microblaze.md (*ashlsi3_byone, *ashrsi3_byone,
> 	*lshrsi3_byone): Test for const1_rtx instead of calling INTVAL on
> 	something that isn't necessarily a CONST_INT.
>
> ---
>   gcc/config/microblaze/microblaze.c  | 5 ++---
>   gcc/config/microblaze/microblaze.md | 6 +++---
>   2 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/config/microblaze/microblaze.c b/gcc/config/microblaze/microblaze.c
> index 746bef1..4850e85 100644
> --- a/gcc/config/microblaze/microblaze.c
> +++ b/gcc/config/microblaze/microblaze.c
> @@ -3322,11 +3322,10 @@ microblaze_expand_shift (rtx operands[])
>   	      || (GET_CODE (operands[1]) == REG)
>   	      || (GET_CODE (operands[1]) == SUBREG));
>
> -  /* Shift by zero -- copy regs if necessary.  */
> +  /* Shift by zero -- copy regs.  */
>     if ((GET_CODE (operands[2]) == CONST_INT) && (INTVAL (operands[2]) == 0))
>       {
> -      if (REGNO (operands[0]) != REGNO (operands[1]))
> -	emit_insn (gen_movsi (operands[0], operands[1]));
> +      emit_insn (gen_movsi (operands[0], operands[1]));
>         return 1;
>       }


Why generate an unnecessary NOP?


-- 
Michael Eager	 eager@eagercon.com
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