[PATCH] dwarf2cfi: Dump row differences before asserting

Kyrill Tkachov kyrylo.tkachov@foss.arm.com
Mon Oct 31 17:20:00 GMT 2016


On 31/10/16 17:15, Segher Boessenkool wrote:
> If maybe_record_trace_start fails because the CFI is inconsistent on two
> paths into a block it currently just ICEs.  This changes it to also dump
> the CFI on those two paths in the dump file; debugging it without that
> information is hopeless.
>
> Tested on powerpc64-linux {-m32,-m64}.  Is this okay for trunk?

+1 from me as a variant of this patch has helped me debug issues
with the CFI.

Kyrill

>
> Segher
>
>
> 2016-10-31  Segher Boessenkool  <segher@kernel.crashing.org>
>
> 	* dwarf2cfi.c (dump_cfi_row): Add forward declaration.
> 	(maybe_record_trace_start): If the CFI is different on the new and
> 	old paths, print out both to the dump file before ICEing.
>
> ---
>   gcc/dwarf2cfi.c | 18 +++++++++++++++++-
>   1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/dwarf2cfi.c b/gcc/dwarf2cfi.c
> index da9da52..19edc28 100644
> --- a/gcc/dwarf2cfi.c
> +++ b/gcc/dwarf2cfi.c
> @@ -2239,6 +2239,8 @@ add_cfis_to_fde (void)
>       }
>   }
>   
> +static void dump_cfi_row (FILE *f, dw_cfi_row *row);
> +
>   /* If LABEL is the start of a trace, then initialize the state of that
>      trace from CUR_TRACE and CUR_ROW.  */
>   
> @@ -2282,7 +2284,21 @@ maybe_record_trace_start (rtx_insn *start, rtx_insn *origin)
>         /* We ought to have the same state incoming to a given trace no
>   	 matter how we arrive at the trace.  Anything else means we've
>   	 got some kind of optimization error.  */
> -      gcc_checking_assert (cfi_row_equal_p (cur_row, ti->beg_row));
> +#if CHECKING_P
> +      if (!cfi_row_equal_p (cur_row, ti->beg_row))
> +	{
> +	  if (dump_file)
> +	    {
> +	      fprintf (dump_file, "Inconsistent CFI state!\n");
> +	      fprintf (dump_file, "SHOULD have:\n");
> +	      dump_cfi_row (dump_file, ti->beg_row);
> +	      fprintf (dump_file, "DO have:\n");
> +	      dump_cfi_row (dump_file, cur_row);
> +	    }
> +
> +	  gcc_unreachable ();
> +	}
> +#endif
>   
>         /* The args_size is allowed to conflict if it isn't actually used.  */
>         if (ti->beg_true_args_size != args_size)



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