Re: [PATCH] Like the fix for PR 86045 but for modulo

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

Mark,

Thanks for taking an interesting in improving gfortran.  At
the moment, I no longer contribute to gfortran development.

-- 
steve


On Thu, Aug 09, 2018 at 03:11:58PM +0100, Mark Eggleston wrote:
> Steven,
> 
> I'm sending this patch to you as it was found when a change to 
> gfc_simplify_mod caused the test for PR 86045 to fail.
> 
> Immediately after gfc_simplify_mod is gfc_simplify_modulo and is 
> similar. Substituting mod with modulo in the test file caused an 
> internal compiler error just like PR 86045.
> 
> Here is the back trace:
> 
> f951: internal compiler error: Segmentation fault
> 0xb7dedf crash_signal
>      ../../gcc/gcc/toplev.c:325
> 0x6546e8 reduce_binary_ac
>      ../../gcc/gcc/fortran/arith.c:1308
> 0x654682 reduce_binary_ac
>      ../../gcc/gcc/fortran/arith.c:1295
> 0x6548cc reduce_binary
>      ../../gcc/gcc/fortran/arith.c:1421
> 0x654b1b eval_intrinsic
>      ../../gcc/gcc/fortran/arith.c:1596
> 0x6552be eval_intrinsic_f3
>      ../../gcc/gcc/fortran/arith.c:1733
> 0x68bb75 simplify_intrinsic_op
>      ../../gcc/gcc/fortran/expr.c:1158
> 0x68bb75 gfc_simplify_expr(gfc_expr*, int)
>      ../../gcc/gcc/fortran/expr.c:1984
> 0x68af17 gfc_reduce_init_expr(gfc_expr*)
>      ../../gcc/gcc/fortran/expr.c:2775
> 0x68db31 gfc_match_init_expr(gfc_expr**)
>      ../../gcc/gcc/fortran/expr.c:2821
> 0x67b5b1 variable_decl
>      ../../gcc/gcc/fortran/decl.c:2678
> 0x67b5b1 gfc_match_data_decl()
>      ../../gcc/gcc/fortran/decl.c:5888
> 0x6d6429 match_word_omp_simd
>      ../../gcc/gcc/fortran/parse.c:93
> 0x6d9b1e match_word
>      ../../gcc/gcc/fortran/parse.c:376
> 0x6d9b1e decode_statement
>      ../../gcc/gcc/fortran/parse.c:376
> 0x6dba44 next_free
>      ../../gcc/gcc/fortran/parse.c:1234
> 0x6dba44 next_statement
>      ../../gcc/gcc/fortran/parse.c:1466
> 0x6dd83c parse_spec
>      ../../gcc/gcc/fortran/parse.c:3674
> 0x6df803 parse_progunit
>      ../../gcc/gcc/fortran/parse.c:5671
> 0x6e0de4 gfc_parse_file()
>      ../../gcc/gcc/fortran/parse.c:6211
> 
> Please find attached the patch to fix the problem.
> 
> regards,
> 
> Mark Eggleston
> 
> -- 
> https://www.codethink.co.uk/privacy.html
> 

> commit 757d9e0eb9a878ddc2d287fe90cfdd55a8d49c24
> Author: Mark Eggleston <markeggleston@codethink.com>
> Date:   Thu Aug 9 14:33:08 2018 +0100
> 
>     Like fix for PR 86045 but for modulo
> 
> diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
> index 2eb467a1915..1739281d6b7 100644
> --- a/gcc/fortran/simplify.c
> +++ b/gcc/fortran/simplify.c
> @@ -5509,54 +5509,57 @@ gfc_simplify_modulo (gfc_expr *a, gfc_expr *p)
>    gfc_expr *result;
>    int kind;
>  
> -  if (a->expr_type != EXPR_CONSTANT || p->expr_type != EXPR_CONSTANT)
> +  /* First check p.  */
> +  if (p->expr_type != EXPR_CONSTANT)
>      return NULL;
>  
> -  kind = a->ts.kind > p->ts.kind ? a->ts.kind : p->ts.kind;
> -  result = gfc_get_constant_expr (a->ts.type, kind, &a->where);
> -
> -  switch (a->ts.type)
> +  /* p shall not be 0.  */
> +  switch (p->ts.type)
>      {
>        case BT_INTEGER:
>  	if (mpz_cmp_ui (p->value.integer, 0) == 0)
>  	  {
> -	    /* Result is processor-dependent. This processor just opts
> -	      to not handle it at all.  */
> -	    gfc_error ("Second argument of MODULO at %L is zero", &a->where);
> -	    gfc_free_expr (result);
> +	    gfc_error ("Argument %qs of MODULO at %L shall not be zero",
> +			"P", &p->where);
>  	    return &gfc_bad_expr;
>  	  }
> -	mpz_fdiv_r (result->value.integer, a->value.integer, p->value.integer);
> -
>  	break;
> -
>        case BT_REAL:
>  	if (mpfr_cmp_ui (p->value.real, 0) == 0)
>  	  {
> -	    /* Result is processor-dependent.  */
> -	    gfc_error ("Second argument of MODULO at %L is zero", &p->where);
> -	    gfc_free_expr (result);
> +	    gfc_error ("Argument %qs of MODULO at %L shall not be zero",
> +			"P", &p->where);
>  	    return &gfc_bad_expr;
>  	  }
> -
> -	gfc_set_model_kind (kind);
> -	mpfr_fmod (result->value.real, a->value.real, p->value.real,
> -		   GFC_RND_MODE);
> -	if (mpfr_cmp_ui (result->value.real, 0) != 0)
> -	  {
> -	    if (mpfr_signbit (a->value.real) != mpfr_signbit (p->value.real))
> -	      mpfr_add (result->value.real, result->value.real, p->value.real,
> -			GFC_RND_MODE);
> -	  }
> -	else
> -	  mpfr_copysign (result->value.real, result->value.real,
> -			 p->value.real, GFC_RND_MODE);
>  	break;
> -
>        default:
>  	gfc_internal_error ("gfc_simplify_modulo(): Bad arguments");
>      }
>  
> +  if (a->expr_type != EXPR_CONSTANT)
> +    return NULL;
> +
> +  kind = a->ts.kind > p->ts.kind ? a->ts.kind : p->ts.kind;
> +  result = gfc_get_constant_expr (a->ts.type, kind, &a->where);
> +
> +  if (a->ts.type == BT_INTEGER)
> +	mpz_fdiv_r (result->value.integer, a->value.integer, p->value.integer);
> +  else
> +    {
> +      gfc_set_model_kind (kind);
> +      mpfr_fmod (result->value.real, a->value.real, p->value.real,
> +                 GFC_RND_MODE);
> +      if (mpfr_cmp_ui (result->value.real, 0) != 0)
> +        {
> +          if (mpfr_signbit (a->value.real) != mpfr_signbit (p->value.real))
> +            mpfr_add (result->value.real, result->value.real, p->value.real,
> +                      GFC_RND_MODE);
> +	    }
> +	  else
> +        mpfr_copysign (result->value.real, result->value.real,
> +                       p->value.real, GFC_RND_MODE);
> +    }
> +
>    return range_check (result, "MODULO");
>  }
>  
> diff --git a/gcc/testsuite/gfortran.dg/modulo_const_array_p_is_zero.f90 b/gcc/testsuite/gfortran.dg/modulo_const_array_p_is_zero.f90
> new file mode 100644
> index 00000000000..1325d0f2e89
> --- /dev/null
> +++ b/gcc/testsuite/gfortran.dg/modulo_const_array_p_is_zero.f90
> @@ -0,0 +1,6 @@
> +program p
> +   logical :: a(2) = (modulo([2,3],0) == 0)     ! { dg-error "shall not be zero" }
> +   integer :: b = count(modulo([2,3],0) == 0)   ! { dg-error "shall not be zero" }
> +   integer :: c = all(modulo([2,3],0) == 0)     ! { dg-error "shall not be zero" }
> +   integer :: d = any(modulo([2,3],0) == 0)     ! { dg-error "shall not be zero" }
> +end program


-- 
Steve
20170425 https://www.youtube.com/watch?v=VWUpyCsUKR4
20161221 https://www.youtube.com/watch?v=IbCHE-hONow