Re: [PATCH] Fix aarch64_simd_reg_or_zero predicate (PR fortran/84565)

[Richard Sandiford <richard.sandiford@linaro.org>]

Jakub Jelinek <jakub@redhat.com> writes:
> Hi!
>
> The following testcase ICEs, because the aarch64_cmeqdf instruction
> starting with r256612 no longer accepts CONST0_RTX (E_DFmode) as
> valid argument, but the expander generates it anyway.
>
> The bug has been introduced during the addition of aarch64_simd_imm_zero
> and aarch64_simd_or_scalar_imm_zero predicates, before the predicate
> used to be:
> (define_predicate "aarch64_simd_reg_or_zero"
>   (and (match_code "reg,subreg,const_int,const_double,const_vector")
>        (ior (match_operand 0 "register_operand")
>            (ior (match_test "op == const0_rtx")
>                 (match_test "aarch64_simd_imm_zero_p (op, mode)")))))
> with
> bool
> aarch64_simd_imm_zero_p (rtx x, machine_mode mode)
> {
>   return x == CONST0_RTX (mode);
> }
> and so matched not just const,const_vector zeros, but also
> const_int zero (that is through op == const0_rtx) and const_double
> zero too.

Thanks for fixing this.

> Bootstrapped/regtested on aarch64-linux (scratch Fedora gcc 8 package build
> with the patch applied), ok for trunk?
>
> 2018-02-27  Jakub Jelinek  <jakub@redhat.com>
>
> 	PR fortran/84565
> 	* config/aarch64/predicates.md (aarch64_simd_reg_or_zero): Use
> 	aarch64_simd_or_scalar_imm_zero rather than aarch64_simd_imm_zero.
>
> 	* gfortran.dg/pr84565.f90: New test.
>
> --- gcc/config/aarch64/predicates.md.jj	2018-02-06 13:13:06.305751221 +0100
> +++ gcc/config/aarch64/predicates.md	2018-02-26 16:30:01.902195208 +0100
> @@ -395,7 +395,7 @@ (define_predicate "aarch64_simd_reg_or_z
>    (and (match_code "reg,subreg,const_int,const_double,const,const_vector")
>         (ior (match_operand 0 "register_operand")
>  	    (match_test "op == const0_rtx")
> -	    (match_operand 0 "aarch64_simd_imm_zero"))))
> +	    (match_operand 0 "aarch64_simd_or_scalar_imm_zero"))))

I think this makes the match_test on the line above redundant.

LGTM otherwise (but I can't approve).  We should probably clean up
the predicates so that the zero checks are more consistent.  genrecog
could probably help by ignoring predicate codes that obviously don't
apply (CONST_INT for vectors, CONST_VECTOR for ints, etc.).  But that's
obviously all stage 1 stuff.

Richard