Re: [PATCH] gdb: Fix false match issue in skip_prologue_using_linetable

[Keith Seitz <keiths@redhat.com>]

On 4/17/23 09:24, WANG Rui wrote:
> We should exclude matches to the ending PC to prevent false matches with the
> next function, as prologue_end is located at the end PC.
> 
>    <fun1>:
>      0x00: ... <-- start_pc
>      0x04: ...
>      0x08: ... <-- breakpoint
>      0x0c: ret
>    <fun2>:
>      0x10: ret <-- end_pc | prologue_end of fun2

Thank you for the patch. Indeed, my recollection is that we always
record/search for pc's in [start, end). find_pc_partial_function seems to
concur.

> ---
>   gdb/symtab.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/gdb/symtab.c b/gdb/symtab.c
> index f2b1a14e006..a662d7d1869 100644
> --- a/gdb/symtab.c
> +++ b/gdb/symtab.c
> @@ -3735,7 +3735,7 @@ skip_prologue_using_linetable (CORE_ADDR func_addr)
>   	 });
>   
>         for (;
> -	   it < linetable->item + linetable->nitems && it->pc <= end_pc;
> +	   it < linetable->item + linetable->nitems && it->pc < end_pc;
>   	   it++)
>   	if (it->prologue_end)
>   	  return {it->pc};

This appears to be against gdb 13 and will need to be rebased.

I have regression tested this on x86_64 and found nothing of concern.
[The patch which introduced this function contained a test case,
gdb.dwarf2/dw2-prologue-end.exp, and that test also shows no regressions.]

I have to ask, though, is there a way to write a test case for this? Maybe
by using dw2-prologue-end.exp as an example?

Keith