Re: [PATCH RFA] step-test.exp changes for IA-64

[Kevin Buettner <kevinb at cygnus dot com>]

This patch was applied earlier today.  At Fernando's request, I added
some additional comments describing the reason for the different behavior
on the IA-64.

On Apr 25,  8:42pm, Kevin Buettner wrote:
> Subject: [PATCH RFA] step-test.exp changes for IA-64
> I request approval for committing the changes below.
> 
> On IA-64, when using "finish" to step out of a function, gdb will stop
> on the line containing the call to the function that you've just
> stepped out of.  The reason for this is that immediately after the
> call instruction is an instruction which restores the global pointer. 
> Since this is part of the sequence of instructions forming the call,
> it makes sense that gdb would place you on the line of the call instead
> of the next executable line after the call.
> 
> To further illustrate what's going on, here's a typical call sequence
> which shows the saving of the global pointer, the call itself, and the
> restoration of the global pointer:
> 
>     0x40000000000007d1 <main+113>:              mov r34=r1
>     0x40000000000007d2 <main+114>:
>                     br.call.sptk.many b0=0x4000000000000870 <foo>;;
>     0x40000000000007e0 <main+128>:  [MII]       mov r1=r34
> 
> The general register r1 is the global pointer (which is a base
> register off of which various data may be found for a particular load
> module).  The final instruction moves the saved value in r34 to r1.
> 
> 	* gdb.base/step-test.exp: On IA-64 targets, when stepping out of
> 	a call, do not require that gdb stop on the line after the call. 
> 	Instead, it is permissible for gdb to stop on the line of the
> 	call itself.
> 
> Index: testsuite/gdb.base/step-test.exp
> ===================================================================
> RCS file: /cvs/src/src/gdb/testsuite/gdb.base/step-test.exp,v
> retrieving revision 1.1.1.7
> diff -u -p -r1.1.1.7 step-test.exp
> --- step-test.exp	2000/02/05 07:30:00	1.1.1.7
> +++ step-test.exp	2000/04/26 03:11:43
> @@ -76,7 +76,7 @@ gdb_test "step" ".*${decimal}.*myglob.*"
>  # call?
>  
>  # On PA64 we end up at a different instruction than PA32
> -if { [istarget "hppa2.0w-hp-hpux*"] } {
> +if { [istarget "hppa2.0w-hp-hpux*"] || [istarget "ia64-*-*"]} {
>      send_gdb "finish\n"
>      gdb_expect {
>          -re ".*${decimal}.*a.*5.*= a.*3.*$gdb_prompt $" { pass "step out 1" }
> @@ -172,7 +172,7 @@ gdb_expect {
>    }
>    -re ".*${decimal}.*callee.*STEPI.*$gdb_prompt $" {
>      # On PA64 we end up at a different instruction than PA32
> -    if { [istarget "hppa2.0w-hp-hpux*"] } {
> +    if { [istarget "hppa2.0w-hp-hpux*"] || [istarget "ia64-*-*"] } {
>          pass "stepi: finish call 2"
>      } else {
>  	fail "stepi: finish call 2"
> 
>-- End of excerpt from Kevin Buettner