Re: [PATCH v2 1/3] gdb: make frame_unwind_got_optimized return a not_lval value

[Pedro Alves <pedro@palves.net>]

On 8/27/20 9:57 PM, Simon Marchi via Gdb-patches wrote:

>  /* Return a value which indicates that FRAME copied REGNUM into
> diff --git a/gdb/frame-unwind.h b/gdb/frame-unwind.h
> index c80ddc84f291..25a601ccf4bb 100644
> --- a/gdb/frame-unwind.h
> +++ b/gdb/frame-unwind.h
> @@ -133,6 +133,9 @@ typedef void (frame_this_id_ftype) (struct frame_info *this_frame,
>     may be a lazy reference to memory, a lazy reference to the value of
>     a register in THIS frame, or a non-lvalue.
>  
> +   If the previous frame's register was not saved by THIS_FRAME and is
> +   therefore undefined, return a not_lval wholly optimized-out value.

Super nit:

"not_lval wholly optimized-out value" doesn't sound as natural
to me as "wholly optimized-out not_lval value" would.

It's just like "register optimized-out value" doesn't sound as
natural as "optimized-out register value" to me.

English adjective order is fun! 
https://www.theguardian.com/commentisfree/2016/sep/13/sentence-order-adjectives-rule-elements-of-eloquence-dictionary
https://www.grammar-monster.com/lessons/order_of_adjectives.htm

> +
>     THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
>     with the other unwind methods.  Memory for that cache should be
>     allocated using FRAME_OBSTACK_ZALLOC().  */
> diff --git a/gdb/frame.c b/gdb/frame.c
> index 7ab3cdcdad41..ccaf97dc7e91 100644
> --- a/gdb/frame.c
> +++ b/gdb/frame.c
> @@ -1295,7 +1295,7 @@ frame_unwind_register_value (frame_info *next_frame, int regnum)
>        if (value_optimized_out (value))
>  	{
>  	  fprintf_unfiltered (gdb_stdlog, " ");
> -	  val_print_optimized_out (value, gdb_stdlog);
> +	  val_print_not_saved (gdb_stdlog);
>  	}
>        else
>  	{
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-reg-undefined.exp b/gdb/testsuite/gdb.dwarf2/dw2-reg-undefined.exp
> index a3e6f28c54f0..4ab7e2dbfc44 100644
> --- a/gdb/testsuite/gdb.dwarf2/dw2-reg-undefined.exp
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-reg-undefined.exp
> @@ -74,3 +74,15 @@ for {set f 0} {$f < 3} {incr f} {
>  		    "r9\\s+${pattern_r8_r9_info}\\s*"] \
>  	"Check values of rax, rbx, rcx, r8, r9 in frame ${f}"
>  }
> +
> +# Test that the debug log statement in frame_unwind_register_value produces
> +# "not saved" and not# "optimized out".

Spurious # after "not".