Re: C PATCH to use is_global_var

[Marek Polacek <polacek at redhat dot com>]

On Wed, Jun 24, 2015 at 05:16:33PM +0000, Joseph Myers wrote:
> On Wed, 24 Jun 2015, Marek Polacek wrote:
> 
> > diff --git gcc/c/c-decl.c gcc/c/c-decl.c
> > index fc1fdf9..ab54db9 100644
> > --- gcc/c/c-decl.c
> > +++ gcc/c/c-decl.c
> > @@ -2650,9 +2650,8 @@ merge_decls (tree newdecl, tree olddecl, tree newtype, tree oldtype)
> >  		  tree_code_size (TREE_CODE (olddecl)) - sizeof (struct tree_decl_common));
> >  	  olddecl->decl_with_vis.symtab_node = snode;
> >  
> > -	  if ((DECL_EXTERNAL (olddecl)
> > -	       || TREE_PUBLIC (olddecl)
> > -	       || TREE_STATIC (olddecl))
> > +	  if ((is_global_var (olddecl)
> > +	       || TREE_PUBLIC (olddecl))
> >  	      && DECL_SECTION_NAME (newdecl) != NULL)
> >  	    set_decl_section_name (olddecl, DECL_SECTION_NAME (newdecl));
> >  
> 
> At least this case covers both FUNCTION_DECL and VAR_DECL.  If 
> is_global_var is appropriate for functions as well as variables, I think 
> it should be renamed (and have its comment updated to explain what it 
> means for functions).

You raise a good point.  After fair amount of investigating, I don't think
is_global_var is appropriate for functions.  (DECL_EXTERNAL || TREE_STATIC)
for a function is only false for weird cases such as an inline function
definition followed by redeclaring this function with noinline attribute, i.e.:

inline void a (void) {}
void a (void) __attribute__ ((noinline));

void
b ()
{
  a ();
}

is_global_var with a FUNCTION_DECL is only called in tree-ssa-structalias.c
and it seems like a mistake.

So I propose to commit the following patch, which uses is_global_var only
at places where we're dealing with a variable.

Ok for trunk?

2015-06-25  Marek Polacek  <polacek@redhat.com>

	* cilk.c (extract_free_variables): Use is_global_var.

	* c-decl.c: Use is_global_var throughout.
	* c-parser.c: Likewise.
	* c-typeck.c: Likewise.

diff --git gcc/c-family/cilk.c gcc/c-family/cilk.c
index c38e05f..347e4b9 100644
--- gcc/c-family/cilk.c
+++ gcc/c-family/cilk.c
@@ -1063,7 +1063,7 @@ extract_free_variables (tree t, struct wrapper_data *wd,
 	TREE_ADDRESSABLE (t) = 1;
     case VAR_DECL:
     case PARM_DECL:
-      if (!TREE_STATIC (t) && !DECL_EXTERNAL (t))
+      if (!is_global_var (t))
 	add_variable (wd, t, how);
       return;
 
diff --git gcc/c/c-decl.c gcc/c/c-decl.c
index fc1fdf9..ab54db9 100644
--- gcc/c/c-decl.c
+++ gcc/c/c-decl.c
@@ -4395,7 +4394,7 @@ c_decl_attributes (tree *node, tree attributes, int flags)
   /* Add implicit "omp declare target" attribute if requested.  */
   if (current_omp_declare_target_attribute
       && ((TREE_CODE (*node) == VAR_DECL
-	   && (TREE_STATIC (*node) || DECL_EXTERNAL (*node)))
+	   && is_global_var (*node))
 	  || TREE_CODE (*node) == FUNCTION_DECL))
     {
       if (TREE_CODE (*node) == VAR_DECL
@@ -4794,8 +4793,7 @@ finish_decl (tree decl, location_t init_loc, tree init,
 	   TREE_TYPE (decl) = error_mark_node;
 	 }
 
-      if ((DECL_EXTERNAL (decl) || TREE_STATIC (decl))
-	  && DECL_SIZE (decl) != 0)
+      if (is_global_var (decl) && DECL_SIZE (decl) != 0)
 	{
 	  if (TREE_CODE (DECL_SIZE (decl)) == INTEGER_CST)
 	    constant_expression_warning (DECL_SIZE (decl));
@@ -4911,8 +4909,7 @@ finish_decl (tree decl, location_t init_loc, tree init,
 	{
 	  /* Recompute the RTL of a local array now
 	     if it used to be an incomplete type.  */
-	  if (was_incomplete
-	      && !TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
+	  if (was_incomplete && !is_global_var (decl))
 	    {
 	      /* If we used it already as memory, it must stay in memory.  */
 	      TREE_ADDRESSABLE (decl) = TREE_USED (decl);
diff --git gcc/c/c-parser.c gcc/c/c-parser.c
index e0ab0a1..f4d18bd 100644
--- gcc/c/c-parser.c
+++ gcc/c/c-parser.c
@@ -14769,7 +14769,7 @@ c_parser_omp_threadprivate (c_parser *parser)
 	error_at (loc, "%qD is not a variable", v);
       else if (TREE_USED (v) && !C_DECL_THREADPRIVATE_P (v))
 	error_at (loc, "%qE declared %<threadprivate%> after first use", v);
-      else if (! TREE_STATIC (v) && ! DECL_EXTERNAL (v))
+      else if (! is_global_var (v))
 	error_at (loc, "automatic variable %qE cannot be %<threadprivate%>", v);
       else if (TREE_TYPE (v) == error_mark_node)
 	;
diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index aeb1043..3dc1f07 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -4380,7 +4380,7 @@ c_mark_addressable (tree exp)
 	if (C_DECL_REGISTER (x)
 	    && DECL_NONLOCAL (x))
 	  {
-	    if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
+	    if (TREE_PUBLIC (x) || is_global_var (x))
 	      {
 		error
 		  ("global register variable %qD used in nested function", x);
@@ -4390,7 +4390,7 @@ c_mark_addressable (tree exp)
 	  }
 	else if (C_DECL_REGISTER (x))
 	  {
-	    if (TREE_PUBLIC (x) || TREE_STATIC (x) || DECL_EXTERNAL (x))
+	    if (TREE_PUBLIC (x) || is_global_var (x))
 	      error ("address of global register variable %qD requested", x);
 	    else
 	      error ("address of register variable %qD requested", x);