Fix aliasing violations

Fix aliasing violations

[Andreas Schwab]

The macro GROW_VECT in ada-lang.h violates the C aliasing rules.

Andreas.

2004-10-23  Andreas Schwab  <schwab@suse.de>

	* ada-lang.c (grow_vect): Return the new array instead of
	expecting pointer to pointer to avoid violation of aliasing rules.
	* ada-lang.h (GROW_VECT): Adapt call to grow_vect.

--- gdb/ada-lang.c	20 Oct 2004 01:01:25 +0200	1.59
+++ gdb/ada-lang.c	23 Oct 2004 20:12:45 +0200	
@@ -319,20 +319,21 @@ extract_string (CORE_ADDR addr, char *bu
   while (buf[char_index - 1] != '\000');
 }
 
-/* Assuming *OLD_VECT points to an array of *SIZE objects of size
+/* Assuming VECT points to an array of *SIZE objects of size
    ELEMENT_SIZE, grow it to contain at least MIN_SIZE objects,
-   updating *OLD_VECT and *SIZE as necessary.  */
+   updating *SIZE as necessary and returning the (new) array.  */
 
-void
-grow_vect (void **old_vect, size_t * size, size_t min_size, int element_size)
+void *
+grow_vect (void *vect, size_t *size, size_t min_size, int element_size)
 {
   if (*size < min_size)
     {
       *size *= 2;
       if (*size < min_size)
         *size = min_size;
-      *old_vect = xrealloc (*old_vect, *size * element_size);
+      vect = xrealloc (vect, *size * element_size);
     }
+  return vect;
 }
 
 /* True (non-zero) iff TARGET matches FIELD_NAME up to any trailing
--- gdb/ada-lang.h	20 Oct 2004 01:01:25 +0200	1.13
+++ gdb/ada-lang.h	23 Oct 2004 20:13:27 +0200	
@@ -171,9 +171,9 @@ extern struct task_entry *task_list;
    least M objects, updating V and S as necessary. */
 
 #define GROW_VECT(v, s, m)                                              \
-   if ((s) < (m)) grow_vect ((void**) &(v), &(s), (m), sizeof(*(v)));
+   if ((s) < (m)) (v) = grow_vect (v, &(s), m, sizeof *(v));
 
-extern void grow_vect (void **, size_t *, size_t, int);
+extern void *grow_vect (void *, size_t *, size_t, int);
 
 extern int ada_get_field_index (const struct type *type,
                                 const char *field_name,

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: Fix aliasing violations

[Daniel Jacobowitz]

On Sat, Oct 23, 2004 at 08:26:28PM +0200, Andreas Schwab wrote:
> The macro GROW_VECT in ada-lang.h violates the C aliasing rules.
> 
> Andreas.
> 
> 2004-10-23  Andreas Schwab  <schwab@suse.de>
> 
> 	* ada-lang.c (grow_vect): Return the new array instead of
> 	expecting pointer to pointer to avoid violation of aliasing rules.
> 	* ada-lang.h (GROW_VECT): Adapt call to grow_vect.

I assume newer versions of GCC warn about this?  This patch is OK.

-- 
Daniel Jacobowitz

Re: Fix aliasing violations

[Andreas Schwab]

Daniel Jacobowitz <drow@false.org> writes:

> On Sat, Oct 23, 2004 at 08:26:28PM +0200, Andreas Schwab wrote:
>> The macro GROW_VECT in ada-lang.h violates the C aliasing rules.
>> 
>> Andreas.
>> 
>> 2004-10-23  Andreas Schwab  <schwab@suse.de>
>> 
>> 	* ada-lang.c (grow_vect): Return the new array instead of
>> 	expecting pointer to pointer to avoid violation of aliasing rules.
>> 	* ada-lang.h (GROW_VECT): Adapt call to grow_vect.
>
> I assume newer versions of GCC warn about this?

Yes, that's -Wstrict-aliasing, part of -Wall.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."