Re: [rfc][00/37] Eliminate builtin_type_ macros

[Joel Brobecker <brobecker@adacore.com>]

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Hi Ulrich,

> I still got a few regressions with our testsuite, which I will
> investigate now. Can you hold the patch off a little while longer?

OK, our testsuite found 2 issues:
 
  1. Pointer arithmetics, in particular "PTR + PTR" or "PTR - PTR"
     expressions. For instance:

       (gdb) print b'address - a'address
       Argument to arithmetic operation not a number or boolean.
     
     It's worth mentioning that the problem was already present
     with pointer addition (adding two pointers doesn't necessarily
     make a lot of sense, but anyway...).

     The regression on the substraction is because we replaced the
     call to (rip'ed) value_sub by a call to value_binop, which
     doesn't support pointer differences.

     I think the semantics of pointer differences in Ada are different
     from C. It's just a number substraction.  So I just added support
     for it directly at the caller site, thus calling value_binop
     only for values that it supports. Same for addition.

  2. The second problem is just an oversight. You needed a variable
     to store the int builtin type, and unfortunately you reused
     a variable that was still in use.
     See ada-lang.c (evaluate_subexp) [OP_ATR_SIZE].

     For now, I just used builtin_type_int32. Not ideal, but should
     be large enough for the vast majority of objects we actually
     have to deal with in real life.

Two suggested patches attached...

BTW: I tested on x86-linux (DWARF & STABS) as well as on x86_64-linux
(DWARF only, obviously).

-- 
Joel

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diff -r ef6e8d4d28b4 -r c0202064b824 ada-lang.c
--- a/ada-lang.c	Tue Sep 09 10:27:10 2008 -0700
+++ b/ada-lang.c	Tue Sep 09 12:31:38 2008 -0700
@@ -9909,6 +9909,10 @@ ada_evaluate_subexp (struct type *expect
       arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
       if (noside == EVAL_SKIP)
         goto nosideret;
+      if (TYPE_CODE (value_type (arg1)) == TYPE_CODE_PTR)
+        return (value_from_longest
+                 (value_type (arg1),
+                  value_as_long (arg1) + value_as_long (arg2)));
       if ((ada_is_fixed_point_type (value_type (arg1))
            || ada_is_fixed_point_type (value_type (arg2)))
           && value_type (arg1) != value_type (arg2))
@@ -9927,6 +9931,10 @@ ada_evaluate_subexp (struct type *expect
       arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
       if (noside == EVAL_SKIP)
         goto nosideret;
+      if (TYPE_CODE (value_type (arg1)) == TYPE_CODE_PTR)
+        return (value_from_longest
+                 (value_type (arg1),
+                  value_as_long (arg1) - value_as_long (arg2)));
       if ((ada_is_fixed_point_type (value_type (arg1))
            || ada_is_fixed_point_type (value_type (arg2)))
           && value_type (arg1) != value_type (arg2))

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diff -r c0202064b824 -r 61698126d402 ChangeLog.joel
diff -r c0202064b824 -r 61698126d402 ada-lang.c
--- a/ada-lang.c	Tue Sep 09 12:31:38 2008 -0700
+++ b/ada-lang.c	Tue Sep 09 12:57:26 2008 -0700
@@ -10541,11 +10541,10 @@ ada_evaluate_subexp (struct type *expect
 
       if (noside == EVAL_SKIP)
         goto nosideret;
-      type = builtin_type (exp->gdbarch)->builtin_int;
       if (noside == EVAL_AVOID_SIDE_EFFECTS)
-        return value_zero (type, not_lval);
-      else
-        return value_from_longest (type,
+        return value_zero (builtin_type_int32, not_lval);
+      else
+        return value_from_longest (builtin_type_int32,
                                    TARGET_CHAR_BIT * TYPE_LENGTH (type));
 
     case OP_ATR_VAL: