[gdb/tdep] Fix nr array elements in ppc64_aggregate_candidate
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Commit Message
On AlmaLinux 9.2 powerpc64le I run into:
...
(gdb) PASS: gdb.ada/array_return.exp: continuing to Create_Small_Float_Vector
finish^M
Run till exit from #0 pck.create_small_float_vector () at pck.adb:30^M
0x00000000100022d4 in p () at p.adb:25^M
25 Vector := Create_Small_Float_Vector;^M
Value returned is $3 = (2.80259693e-45, 2.80259693e-45)^M
(gdb) FAIL: gdb.ada/array_return.exp: value printed by finish of Create_Small_Float_Vector
...
while this is expected:
...
Value returned is $3 = (4.25, 4.25)^M
...
The problem is here in ppc64_aggregate_candidate:
...
if (!get_array_bounds (type, &low_bound, &high_bound))
return -1;
count *= high_bound - low_bound
...
The array type (containing 2 elements) is:
...
type Small_Float_Vector is array (1 .. 2) of Float;
...
so we have:
...
(gdb) p low_bound
$1 = 1
(gdb) p high_bound
$2 = 2
...
but we calculate the number of elements in the array using
"high_bound - low_bound", which is 1.
Consequently, gdb fails to correctly classify the type as a ELFv2 homogeneous
aggregate.
Fix this by calculating the number of elements in the array by using
"high_bound - low_bound + 1" instead.
Furthermore, high_bound can (in general, though perhaps not here) be also be
smaller than low_bound, so to be safe take that into account as well:
...
LONGEST nr_array_elements = (low_bound > high_bound
? 0
: (high_bound - low_bound + 1));
count *= nr_array_elements;
...
Tested on powerpc64le-linux.
PR tdep/31015
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31015
---
gdb/ppc-sysv-tdep.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
base-commit: f514e6e48061661cacfc980cd5272fd99887d38b
Comments
Tom de Vries <tdevries@suse.de> wrote:
>Fix this by calculating the number of elements in the array by using
>"high_bound - low_bound + 1" instead.
>
>Furthermore, high_bound can (in general, though perhaps not here) be also be
>smaller than low_bound, so to be safe take that into account as well:
>...
> LONGEST nr_array_elements = (low_bound > high_bound
> ? 0
> : (high_bound - low_bound + 1));
> count *= nr_array_elements;
>...
I see. This does appear to be a bug, indeed.
The patch looks good to me.
Bye,
Ulrich
@@ -1127,7 +1127,11 @@ ppc64_aggregate_candidate (struct type *type,
if (!get_array_bounds (type, &low_bound, &high_bound))
return -1;
- count *= high_bound - low_bound;
+
+ LONGEST nr_array_elements = (low_bound > high_bound
+ ? 0
+ : (high_bound - low_bound + 1));
+ count *= nr_array_elements;
/* There must be no padding. */
if (count == 0)