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Re: [PATCH] The parameter in value_entirely_optimized_out is NULL
- From: Pedro Alves <palves at redhat dot com>
- To: åæ ä <kiki-good at hotmail dot com>, "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Wed, 18 May 2016 12:44:20 +0100
- Subject: Re: [PATCH] The parameter in value_entirely_optimized_out is NULL
- Authentication-results: sourceware.org; auth=none
- References: <BLU181-W693D4F7D046CA8E692959AE1480 at phx dot gbl>
On 05/17/2016 03:45 PM, 建明 乔 wrote:
> Hi:
>
FYI, something is odd with your emails -- lots of seemingly spurious empty lines:
https://sourceware.org/ml/gdb-patches/2016-05/msg00259.html
Also, the follow up reply you sent was quite garbled, and it doesn't look
like it managed to reach the list.
>
>
> The GDB(v7.7 onwards) will crash at value_entirely_optimized_out (value=0x0) in some cases.
>
>
>
> These cases are reported in GDB Database as Bug 20020,17076,17685 in X86 platform
>
>
>
> and other reports that use cross-compiled GDB host(ARM & MIPS) from our side.
I tried a couple tests from those bug reports, and I couldn't reproduce the problem
with current master. Can you reproduce it reliably? It'd be great to have a testcase
in the testsuite for this. Best would probably be to write it using the Dwarf::assemble
mechanism (gdb/testsuite/gdb.dwarf2/).
>
>
>
>
> This bug is introduced when the patch https://sourceware.org/ml/gdb-patches/2013-10/msg00353.html is added.
>
>
>
> The code from this patch that caused the regression is listed below:
>
>
>
>
> diff --git a/gdb/cp-valprint.c b/gdb/cp-valprint.c
> index 1d7147c..4b625d1 100644
> --- a/gdb/cp-valprint.c
> +++ b/gdb/cp-valprint.c
> @@ -333,12 +333,9 @@ cp_print_value_fields (struct type *type, struct type *real_type,
> fprintf_filtered (stream,
> _("<error reading variable: %s>"),
> ex.message);
> - else if (v == NULL)
> - val_print_optimized_out (NULL, stream);
> - else
> - cp_print_static_field (TYPE_FIELD_TYPE (type, i),
> - v, stream, recurse + 1,
> - options);
> + cp_print_static_field (TYPE_FIELD_TYPE (type, i),
> + v, stream, recurse + 1,
> + options);
> }
>
>
>
>
> Therefore, I propose to partly revert the previous patch and apply the change below.
>
>
>
>
> Is it acceptable ?
Can't tell without a more expanded rationale for the change. E.g.,:
- Why is 'v' NULL here?
- Why is it OK for 'v' to be NULL here?
Thanks,
Pedro Alves