Enhance debug info for fixed-point types

The Ada language supports fixed-point types as first-class citizens so
they need to be described as-is in the debug info.  We devised the
langhook get_fixed_point_type_info for this purpose a few years ago,
but it comes with a limitation for the representation of the scale
factor that we would need to lift in order to be able to represent
more fixed-point types.

gcc/ChangeLog:
	* dwarf2out.h (struct fixed_point_type_info) <scale_factor>: Turn
	numerator and denominator into a tree.
	* dwarf2out.c (base_type_die): In the case of a fixed-point type
	with arbitrary scale factor, call add_scalar_info on numerator and
	denominator to emit the appropriate attributes.

gcc/ada/ChangeLog:
	* exp_dbug.adb (Is_Handled_Scale_Factor): Delete.
	(Get_Encoded_Name): Do not call it.
	* gcc-interface/decl.c (gnat_to_gnu_entity) <Fixed_Point_Type>:
	Tidy up and always use a meaningful description for arbitrary
	scale factors.
	* gcc-interface/misc.c (gnat_get_fixed_point_type_info): Remove
	obsolete block and adjust the description of the scale factor.

1 files changed, 6 insertions, 11 deletions

diff --git a/gcc/dwarf2out.h b/gcc/dwarf2out.h
index 9571f8b..0b06cff 100644
--- a/gcc/dwarf2out.h
+++ b/gcc/dwarf2out.h
@@ -362,23 +362,18 @@ enum fixed_point_scale_factor
 
 struct fixed_point_type_info
 {
-  /* A scale factor is the value one has to multiply with physical data in
-     order to get the fixed point logical data.  The DWARF standard enables one
-     to encode it in three ways.  */
+  /* The scale factor is the value one has to multiply the actual data with
+     to get the fixed point value.  We support three ways to encode it.  */
   enum fixed_point_scale_factor scale_factor_kind;
   union
     {
-      /* For binary scale factor, the scale factor is: 2 ** binary.  */
+      /* For a binary scale factor, the scale factor is 2 ** binary.  */
       int binary;
-      /* For decimal scale factor, the scale factor is: 10 ** binary.  */
+      /* For a decimal scale factor, the scale factor is 10 ** decimal.  */
       int decimal;
-      /* For arbitrary scale factor, the scale factor is:
+      /* For an arbitrary scale factor, the scale factor is the ratio
 	 numerator / denominator.  */
-      struct
-	{
-	  unsigned HOST_WIDE_INT numerator;
-	  HOST_WIDE_INT denominator;
-	} arbitrary;
+      struct { tree numerator; tree denominator; } arbitrary;
     } scale_factor;
 };