[PATCH][gdb/testsuite] Fix gdb.fortran/array-slices.exp with -m32

[PATCH][gdb/testsuite] Fix gdb.fortran/array-slices.exp with -m32

[Tom de Vries]

Hi,

When running test-case gdb.fortran/array-slices.exp with target board
unix/-m32, we run into:
...
(gdb) print /x &array4d^M
$69 = 0xffffb620^M
(gdb) print /x (&array4d) + sizeof (array4d)^M
$70 = 0x95c620^M
(gdb) FAIL: gdb.fortran/array-slices.exp: repack=on: test 9: check sizes match
...
The expressions calculate the start and end of an array, but the calculation
of the end expression has an unexpected result (given that it lies before the
start of the array).  By printing "sizeof (array4d)" as a separate
expression:
...
(gdb) print /x sizeof (array4d)
$1 = 0xc40
...
it becomes clear we expected to get 0xffffb620 + 0xc40 == 0xffffc260 instead.

The problem is that using the '&' returns a pointer type:
...
(gdb) p &array4d
$5 = (PTR TO -> ( integer(kind=4) (-3:3,7:10,-3:3,-10:-7) )) 0xffffbe00
...
which has the consequence that the addition is done as pointer arithmetic.

Fix this by using the result of "print /x &array4d" instead of &array4d in the
addition.

Tested on x86_64-linux.

Any comments?

Thanks,
- Tom

[gdb/testsuite] Fix gdb.fortran/array-slices.exp with -m32

gdb/testsuite/ChangeLog:

2021-01-15  Tom de Vries  <tdevries@suse.de>

	PR testsuite/26997
	* gdb.fortran/array-slices.exp (run_test): Avoid pointer arithmetic
	when adding sizeof.

---
 gdb/testsuite/gdb.fortran/array-slices.exp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.fortran/array-slices.exp b/gdb/testsuite/gdb.fortran/array-slices.exp
index f45a299b268..45753d9baea 100644
--- a/gdb/testsuite/gdb.fortran/array-slices.exp
+++ b/gdb/testsuite/gdb.fortran/array-slices.exp
@@ -208,7 +208,7 @@ proc run_test { repack } {
 	    set start_addr [get_hexadecimal_valueof "&${full_var_name}" \
 				"start unknown"]
 	    set end_addr [get_hexadecimal_valueof \
-			      "(&${full_var_name}) + sizeof (${full_var_name})" \
+			      "$start_addr + sizeof (${full_var_name})" \
 			      "end unknown"]
 
 	    # The Fortran compiler can choose to either send a descriptor that

Re: [PATCH][gdb/testsuite] Fix gdb.fortran/array-slices.exp with -m32

[Andrew Burgess]

* Tom de Vries <tdevries@suse.de> [2021-01-15 11:03:23 +0100]:

> Hi,
> 
> When running test-case gdb.fortran/array-slices.exp with target board
> unix/-m32, we run into:
> ...
> (gdb) print /x &array4d^M
> $69 = 0xffffb620^M
> (gdb) print /x (&array4d) + sizeof (array4d)^M
> $70 = 0x95c620^M
> (gdb) FAIL: gdb.fortran/array-slices.exp: repack=on: test 9: check sizes match
> ...
> The expressions calculate the start and end of an array, but the calculation
> of the end expression has an unexpected result (given that it lies before the
> start of the array).  By printing "sizeof (array4d)" as a separate
> expression:
> ...
> (gdb) print /x sizeof (array4d)
> $1 = 0xc40
> ...
> it becomes clear we expected to get 0xffffb620 + 0xc40 == 0xffffc260 instead.
> 
> The problem is that using the '&' returns a pointer type:
> ...
> (gdb) p &array4d
> $5 = (PTR TO -> ( integer(kind=4) (-3:3,7:10,-3:3,-10:-7) )) 0xffffbe00
> ...
> which has the consequence that the addition is done as pointer arithmetic.
> 
> Fix this by using the result of "print /x &array4d" instead of &array4d in the
> addition.
> 
> Tested on x86_64-linux.
> 
> Any comments?
> 
> Thanks,
> - Tom
> 
> [gdb/testsuite] Fix gdb.fortran/array-slices.exp with -m32
> 
> gdb/testsuite/ChangeLog:
> 
> 2021-01-15  Tom de Vries  <tdevries@suse.de>
> 
> 	PR testsuite/26997
> 	* gdb.fortran/array-slices.exp (run_test): Avoid pointer arithmetic
> 	when adding sizeof.

LGTM.

Thanks,
Andrew

> 
> ---
>  gdb/testsuite/gdb.fortran/array-slices.exp | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/gdb/testsuite/gdb.fortran/array-slices.exp b/gdb/testsuite/gdb.fortran/array-slices.exp
> index f45a299b268..45753d9baea 100644
> --- a/gdb/testsuite/gdb.fortran/array-slices.exp
> +++ b/gdb/testsuite/gdb.fortran/array-slices.exp
> @@ -208,7 +208,7 @@ proc run_test { repack } {
>  	    set start_addr [get_hexadecimal_valueof "&${full_var_name}" \
>  				"start unknown"]
>  	    set end_addr [get_hexadecimal_valueof \
> -			      "(&${full_var_name}) + sizeof (${full_var_name})" \
> +			      "$start_addr + sizeof (${full_var_name})" \
>  			      "end unknown"]
>  
>  	    # The Fortran compiler can choose to either send a descriptor that