[RFA] Fix scm-ports.exp regression

[Pedro Alves]

On 01/03/2018 06:20 PM, Tom Tromey wrote:
> In https://sourceware.org/ml/gdb-patches/2017-12/msg00215.html, Jan
> pointed out that the scalar printing patches caused a regression in
> scm-ports.exp on x86.
> 
> I think the simplest fix is to use "print/u" rather than "print/d" to
> get the value of sp_reg in the test case.

Can you expand a bit on this rationale, please?

There's:

 (parse-and-eval \"*(char*) \$sp\")

in the context of the diff.  Is that related?  I ask because
that "char" in there would look like something that could print
as signed or unsigned depending on target.

It'll probably be obvious with a bit more info.

Thanks,
Pedro Alves

> 
> Tested on x86-64 Fedora 26 using an ordinary build and also a -m32
> build.
> 
> 2018-01-03  Tom Tromey  <tom@tromey.com>
> 
> 	* gdb.guile/scm-ports.exp (test_mem_port_rw): Use get_valueof to
> 	compute sp_reg.
> ---
>  gdb/testsuite/ChangeLog               | 5 +++++
>  gdb/testsuite/gdb.guile/scm-ports.exp | 2 +-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
> index 500dbddf1c..e3903cca6b 100644
> --- a/gdb/testsuite/ChangeLog
> +++ b/gdb/testsuite/ChangeLog
> @@ -1,3 +1,8 @@
> +2018-01-03  Tom Tromey  <tom@tromey.com>
> +
> +	* gdb.guile/scm-ports.exp (test_mem_port_rw): Use get_valueof to
> +	compute sp_reg.
> +
>  2018-01-03  Xavier Roirand  <roirand@adacore.com>
>  
>  	* gdb.ada/excep_handle.exp: New testcase.
> diff --git a/gdb/testsuite/gdb.guile/scm-ports.exp b/gdb/testsuite/gdb.guile/scm-ports.exp
> index 48af5e30e1..04170ef4b8 100644
> --- a/gdb/testsuite/gdb.guile/scm-ports.exp
> +++ b/gdb/testsuite/gdb.guile/scm-ports.exp
> @@ -104,7 +104,7 @@ proc test_mem_port_rw { kind } {
>  	    "get sp reg"
>  	# Note: Only use $sp_reg for gdb_test result matching, don't use it in
>  	# gdb commands.  Otherwise transcript.N becomes unusable.
> -	set sp_reg [get_integer_valueof "\$sp" 0]
> +	set sp_reg [get_valueof /u "\$sp" 0]
>  	gdb_test_no_output "guile (define byte-at-sp (parse-and-eval \"*(char*) \$sp\"))" \
>  	    "save current value at sp"
>  	# Pass the result of parse-and-eval through value-fetch-lazy!,
>