[AVR] inferior call of subprogram with pointer as argument

On AVR, the gdb view of an address is different from the machine view of the
same address.  We need to use special machinery implemented by value_pointer
to take the pointer of a value.

For instance, considering the following function...

  procedure Trace (Unit    : T; Message : String);

... where T is an access Integer (a pointer to an integer), call to this
function currently triggers the following warnings:

    (gdb) call debug.trace (me, "You")
    warning: Value does not fit in 16 bits.
    warning: Value does not fit in 16 bits.
    Tracing message: You

It could have been worse if Trace actually tried to dereference the Unit
argument...

gdb/ChangeLog (from Tristan Gingold):

	* ada-lang.c (value_pointer): New function.
	(make_array_descriptor): Call value_pointer to convert addresses to
	pointers.

Tested on avr and x86_64-linux.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e56a6a1..f220340 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2010-04-20  Joel Brobecker  <brobecker@adacore.com>
 
+       * ada-lang.c (value_pointer): New function.
+       (make_array_descriptor): Call value_pointer to convert addresses to
+       pointers.
+
+2010-04-20  Joel Brobecker  <brobecker@adacore.com>
+
        * rs6000-aix-tdep.c: #include exceptions.h.
        (rs6000_convert_from_func_ptr_addr): If an exception is thrown
        while reading the memory at ADDR, then ADDR cannot be a function

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index a598c6d..abc9c9f 100644 (file)
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -3863,6 +3863,25 @@ ada_convert_actual (struct value *actual, struct type *formal_type0,
   return actual;
 }
 
+/* Convert VALUE (which must be an address) to a CORE_ADDR that is a pointer of
+   type TYPE.  This is usually an inefficient no-op except on some targets
+   (such as AVR) where the representation of a pointer and an address
+   differs.  */
+
+static CORE_ADDR
+value_pointer (struct value *value, struct type *type)
+{
+  struct gdbarch *gdbarch = get_type_arch (type);
+  unsigned len = TYPE_LENGTH (type);
+  gdb_byte *buf = alloca (len);
+  CORE_ADDR addr;
+
+  addr = value_address (value);
+  gdbarch_address_to_pointer (gdbarch, type, buf, addr);
+  addr = extract_unsigned_integer (buf, len, gdbarch_byte_order (gdbarch));
+  return addr;
+}
+
 
 /* Push a descriptor of type TYPE for array value ARR on the stack at
    *SP, updating *SP to reflect the new descriptor.  Return either
@@ -3898,13 +3917,15 @@ make_array_descriptor (struct type *type, struct value *arr,
 
   modify_general_field (value_type (descriptor),
                        value_contents_writeable (descriptor),
-                        value_address (ensure_lval (arr, gdbarch, sp)),
+                        value_pointer (ensure_lval (arr, gdbarch, sp),
+                                       TYPE_FIELD_TYPE (desc_type, 0)),
                         fat_pntr_data_bitpos (desc_type),
                         fat_pntr_data_bitsize (desc_type));
 
   modify_general_field (value_type (descriptor),
                        value_contents_writeable (descriptor),
-                        value_address (bounds),
+                        value_pointer (bounds,
+                                       TYPE_FIELD_TYPE (desc_type, 1)),
                         fat_pntr_bounds_bitpos (desc_type),
                         fat_pntr_bounds_bitsize (desc_type));