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

[Andrew Burgess <andrew.burgess@embecosm.com>]

* 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