[PATCH v6 04/15] vla: enable sizeof operator to work with variable length arrays

[Sanimir Agovic <sanimir.agovic@intel.com>]

In C99 the sizeof operator computes the size of a variable length array
at runtime (6.5.3.4 The sizeof operator). This patch reflects the semantic
change in the debugger.

We now are able to get the size of a vla:

1| void foo (size_t n) {
2|   int vla[n];
3| }

(gdb) p sizeof(vla)

yields N * sizeof(int).

2013-10-18  Sanimir Agovic  <sanimir.agovic@intel.com>
            Keven Boell  <keven.boell@intel.com>

	* eval.c (evaluate_subexp_for_sizeof) <OP_VAR_VALUE>: If the type
	passed to sizeof is dynamic evaluate the argument to compute the length.


Signed-off-by: Sanimir Agovic <sanimir.agovic@intel.com>
---
 gdb/eval.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gdb/eval.c b/gdb/eval.c
index 9d81a92..a81e789 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -3041,8 +3041,14 @@ evaluate_subexp_for_sizeof (struct expression *exp, int *pos)
       return value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
 
     case OP_VAR_VALUE:
-      (*pos) += 4;
       type = check_typedef (SYMBOL_TYPE (exp->elts[pc + 2].symbol));
+      if (is_dynamic_type (type))
+	{
+	  val = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_NORMAL);
+	  type = value_type (val);
+	}
+      else
+	(*pos) += 4;
       return
 	value_from_longest (size_type, (LONGEST) TYPE_LENGTH (type));
 
-- 
1.8.4.2