[PATCH] Fix sparc prologue skipping

[Andrew Burgess]

* Tom Tromey <tromey@adacore.com> [2020-09-18 14:39:14 -0600]:

> sparc can fail at inline prologue skipping.  Andrew Burgess tracked
> this down to sparc32_skip_prologue, which should use
> skip_prologue_using_sal rather than its hand-rolled variant.
> 
> I don't have a good way to test this with the gdb test suite (is there
> a board file for using qemu?  That would help), but it fixes a
> regression in the internal AdaCore test suite.  We've had this patch
> internally at AdaCore for a while, but I just now finally got around
> to making sure that backing it out reintroduces the problem.
> 
> gdb/ChangeLog
> 2020-09-18  Tom Tromey  <tromey@adacore.com>
> 
> 	* sparc-tdep.c (sparc32_skip_prologue): Use
> 	skip_prologue_using_sal.

LGTM.

Thanks,
Andrew

> ---
>  gdb/ChangeLog    |  5 +++++
>  gdb/sparc-tdep.c | 13 +++++++------
>  2 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/gdb/sparc-tdep.c b/gdb/sparc-tdep.c
> index e9636cd8a74..8417a47855f 100644
> --- a/gdb/sparc-tdep.c
> +++ b/gdb/sparc-tdep.c
> @@ -1127,18 +1127,19 @@ static CORE_ADDR
>  sparc32_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
>  {
>    struct symtab_and_line sal;
> -  CORE_ADDR func_start, func_end;
> +  CORE_ADDR func_addr;
>    struct sparc_frame_cache cache;
>  
>    /* This is the preferred method, find the end of the prologue by
>       using the debugging information.  */
> -  if (find_pc_partial_function (start_pc, NULL, &func_start, &func_end))
> +
> +  if (find_pc_partial_function (start_pc, NULL, &func_addr, NULL))
>      {
> -      sal = find_pc_line (func_start, 0);
> +      CORE_ADDR post_prologue_pc
> +	= skip_prologue_using_sal (gdbarch, func_addr);
>  
> -      if (sal.end < func_end
> -	  && start_pc <= sal.end)
> -	return sal.end;
> +      if (post_prologue_pc != 0)
> +	return std::max (start_pc, post_prologue_pc);
>      }
>  
>    start_pc = sparc_analyze_prologue (gdbarch, start_pc, 0xffffffffUL, &cache);
> -- 
> 2.26.2
>