[patch] Add support for FP bit fields in varasm.c

[Eric Botcazou]

Hi,

another kind of bit fields supported in Ada are floating-point bit fields.
They work fine, except that varasm.c rejects static constants (CONSTRUCTORs)
containing them.  The attached patch plugs this hole.

Tested on x86_64-suse-linux, OK for mainline?


2012-03-28  Eric Botcazou  <ebotca...@adacore.com>

        * varasm.c (initializer_constant_valid_for_bitfield_p): Return true
        for REAL_CST as well.
        (output_constructor): Use RECORD_OR_UNION_TYPE_P predicate.
        In the bitfield case, if the value is a REAL_CST, convert it first to
        an INTEGER_CST.


2012-03-28  Eric Botcazou  <ebotca...@adacore.com>

        * gnat.dg/specs/aggr5.ads: New test.


-- 
Eric Botcazou

Index: varasm.c
===================================================================
--- varasm.c	(revision 185857)
+++ varasm.c	(working copy)
@@ -4420,6 +4420,7 @@ initializer_constant_valid_for_bitfield_
       }
 
     case INTEGER_CST:
+    case REAL_CST:
       return true;
 
     case VIEW_CONVERT_EXPR:
@@ -5075,10 +5076,7 @@ output_constructor (tree exp, unsigned H
 
       /* The element in a union constructor specifies the proper field
 	 or index.  */
-      if ((TREE_CODE (local.type) == RECORD_TYPE
-	   || TREE_CODE (local.type) == UNION_TYPE
-	   || TREE_CODE (local.type) == QUAL_UNION_TYPE)
-	  && ce->index != NULL_TREE)
+      if (RECORD_OR_UNION_TYPE_P (local.type) && ce->index != NULL_TREE)
 	local.field = ce->index;
 
       else if (TREE_CODE (local.type) == ARRAY_TYPE)
@@ -5110,9 +5108,17 @@ output_constructor (tree exp, unsigned H
 		   || !CONSTRUCTOR_BITFIELD_P (local.field)))
 	output_constructor_regular_field (&local);
 
-      /* For a true bitfield or part of an outer one.  */
+      /* For a true bitfield or part of an outer one.  Only INTEGER_CSTs are
+	 supported for scalar fields, so we may need to convert first.  */
       else
-	output_constructor_bitfield (&local, outer);
+        {
+	  if (TREE_CODE (local.val) == REAL_CST)
+	    local.val = fold_build1 (VIEW_CONVERT_EXPR,
+				     make_signed_type
+				     (TYPE_PRECISION (TREE_TYPE (local.val))),
+				     local.val);
+	  output_constructor_bitfield (&local, outer);
+	}
     }
 
   /* If we are not at toplevel, save the pending data for our caller.

-- { dg-do compile }

pragma Restrictions (No_Elaboration_Code);

package Aggr5 is

  type R is record
    C : Character;
    F : Float;
  end record;

  for R use record
    C at 0 range 0 .. 7;
    F at 1 range 0 .. 31;
  end record;

  My_R : R := (C => 'A', F => 1.0);

end Aggr5;