[PING^2][RFC] Use gfc_decl_attributes in fortran frontend

Tom de Vries Tom_deVries@mentor.com
Fri May 18 08:07:00 GMT 2018 

On 01/13/2016 05:21 PM, Tom de Vries wrote:
> On 17/12/15 13:08, Tom de Vries wrote:
>> Hi,
>>
>> Consider this patch, which reduces max_len of the oacc function
>> attribute to 0:
>> ...
>> diff --git a/gcc/fortran/f95-lang.c b/gcc/fortran/f95-lang.c
>> index 8556b70..60f4ad3 100644
>> --- a/gcc/fortran/f95-lang.c
>> +++ b/gcc/fortran/f95-lang.c
>> @@ -93,7 +93,7 @@ static const struct attribute_spec
>> gfc_attribute_table[] =
>>          affects_type_identity } */
>>     { "omp declare target", 0, 0, true,  false, false,
>>       gfc_handle_omp_declare_target_attribute, false },
>> -  { "oacc function", 0, -1, true,  false, false,
>> +  { "oacc function", 0, 0, true,  false, false,
>>       gfc_handle_omp_declare_target_attribute, false },
>>     { NULL,                0, 0, false, false, false, NULL, false }
>>   };
>> ...
>>
>> The patch is obviously incorrect, but the idea here is to try to trigger
>> this error in decl_attributes:
>> ...
>>        else if (list_length (args) < spec->min_length
>>                 || (spec->max_length >= 0
>>                     && list_length (args) > spec->max_length))
>>      {
>>            error ("wrong number of arguments specified for %qE"
>>                   " attribute",
>>                   name);
>> ...
>>
>> When running goacc.exp=routine-4.f90, we trigger the error, but then run
>> into an assert.
>>
>> The assert is caused by the fact that %qE is not handled by the fortran
>> format decoder gfc_format_decoder, so this assert triggers in pp_format:
>> ...
>>      ok = pp_format_decoder (pp) (pp, text, p,
>>                   precision, wide, plus, hash);
>>      gcc_assert (ok);
>> ...
>>
>>
>> So, it seems that we call decl_attributes from the fortran frontend
>> without installing a format decoder that can handle any potential errors.
>>
>> This patch attempts to fix that, but having little experience in both
>> diagnostics and fortran frontend, I'm not sure if this is the right way.
>>
>> After applying the patch, the assert is fixed and we can see the actual
>> error without having to start up the debugger:
>> ...
>> src/gcc/testsuite/gfortran.dg/goacc/routine-4.f90:121:0: Error: wrong
>> number of arguments specified for ‘oacc function’ attribute
>> ...
>>
>> Thanks,
>> - Tom
>>
>> 0001-Use-gfc_decl_attributes-in-fortran-frontend.patch
>>
>>
>> Use gfc_decl_attributes in fortran frontend
>>
>> ---
>>   gcc/fortran/error.c      | 18 ++++++++++++++++--
>>   gcc/fortran/gfortran.h   |  2 ++
>>   gcc/fortran/trans-decl.c | 18 ++++++++++++++----
>>   3 files changed, 32 insertions(+), 6 deletions(-)
>>
>> diff --git a/gcc/fortran/error.c b/gcc/fortran/error.c
>> index 8f57aff..fd66d75 100644
>> --- a/gcc/fortran/error.c
>> +++ b/gcc/fortran/error.c
>> @@ -1417,11 +1417,18 @@ gfc_errors_to_warnings (bool f)
>>   }
>>
>>   void
>> -gfc_diagnostics_init (void)
>> +gfc_diagnostics_fortran (void)
>>   {
>>     diagnostic_starter (global_dc) = gfc_diagnostic_starter;
>>     diagnostic_finalizer (global_dc) = gfc_diagnostic_finalizer;
>>     diagnostic_format_decoder (global_dc) = gfc_format_decoder;
>> +}
>> +
>> +void
>> +gfc_diagnostics_init (void)
>> +{
>> +  gfc_diagnostics_fortran ();
>> +
>>     global_dc->caret_chars[0] = '1';
>>     global_dc->caret_chars[1] = '2';
>>     pp_warning_buffer = new (XNEW (output_buffer)) output_buffer ();
>> @@ -1433,13 +1440,20 @@ gfc_diagnostics_init (void)
>>   }
>>
>>   void
>> -gfc_diagnostics_finish (void)
>> +gfc_diagnostics_tree (void)
>>   {
>>     tree_diagnostics_defaults (global_dc);
>>     /* We still want to use the gfc starter and finalizer, not the tree
>>        defaults.  */
>>     diagnostic_starter (global_dc) = gfc_diagnostic_starter;
>>     diagnostic_finalizer (global_dc) = gfc_diagnostic_finalizer;
>> +}
>> +
>> +void
>> +gfc_diagnostics_finish (void)
>> +{
>> +  gfc_diagnostics_tree ();
>> +
>>     global_dc->caret_chars[0] = '^';
>>     global_dc->caret_chars[1] = '^';
>>   }
>> diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
>> index d203c32..1f7cdc2 100644
>> --- a/gcc/fortran/gfortran.h
>> +++ b/gcc/fortran/gfortran.h
>> @@ -2687,6 +2687,8 @@ bool gfc_find_sym_in_expr (gfc_symbol *, 
>> gfc_expr *);
>>   void gfc_error_init_1 (void);
>>   void gfc_diagnostics_init (void);
>>   void gfc_diagnostics_finish (void);
>> +void gfc_diagnostics_fortran (void);
>> +void gfc_diagnostics_tree (void);
>>   void gfc_buffer_error (bool);
>>
>>   const char *gfc_print_wide_char (gfc_char_t);
>> diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
>> index 8c4fa03..9ed1d07 100644
>> --- a/gcc/fortran/trans-decl.c
>> +++ b/gcc/fortran/trans-decl.c
>> @@ -1326,6 +1326,16 @@ add_attributes_to_decl (symbol_attribute 
>> sym_attr, tree list)
>>   }
>>
>>
>> +static tree
>> +gfc_decl_attributes (tree *node, tree attributes, int flags)
>> +{
>> +  tree res;
>> +  gfc_diagnostics_tree ();
>> +  res = decl_attributes (node, attributes, flags);
>> +  gfc_diagnostics_fortran ();
>> +  return res;
>> +}
>> +
>>   static void build_function_decl (gfc_symbol * sym, bool global);
>>
>>
>> @@ -1567,7 +1577,7 @@ gfc_get_symbol_decl (gfc_symbol * sym)
>>
>>     /* Add attributes to variables.  Functions are handled elsewhere.  */
>>     attributes = add_attributes_to_decl (sym->attr, NULL_TREE);
>> -  decl_attributes (&decl, attributes, 0);
>> +  gfc_decl_attributes (&decl, attributes, 0);
>>
>>     /* Symbols from modules should have their assembler names mangled.
>>        This is done here rather than in gfc_finish_var_decl because it
>> @@ -1802,7 +1812,7 @@ get_proc_pointer_decl (gfc_symbol *sym)
>>       set_decl_tls_model (decl, decl_default_tls_model (decl));
>>
>>     attributes = add_attributes_to_decl (sym->attr, NULL_TREE);
>> -  decl_attributes (&decl, attributes, 0);
>> +  gfc_decl_attributes (&decl, attributes, 0);
>>
>>     return decl;
>>   }
>> @@ -1995,7 +2005,7 @@ module_sym:
>>     TREE_PUBLIC (fndecl) = 1;
>>
>>     attributes = add_attributes_to_decl (sym->attr, NULL_TREE);
>> -  decl_attributes (&fndecl, attributes, 0);
>> +  gfc_decl_attributes (&fndecl, attributes, 0);
>>
>>     gfc_set_decl_assembler_name (fndecl, mangled_name);
>>
>> @@ -2097,7 +2107,7 @@ build_function_decl (gfc_symbol * sym, bool global)
>>       TREE_USED (fndecl) = 1;
>>
>>     attributes = add_attributes_to_decl (attr, NULL_TREE);
>> -  decl_attributes (&fndecl, attributes, 0);
>> +  gfc_decl_attributes (&fndecl, attributes, 0);
>>
>>     /* Figure out the return type of the declared function, and build a
>>        RESULT_DECL for it.  If this is a subroutine with alternate
>>
>

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