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Re: [PATCH] Fix gdb crash when trying to print the address of a synthetic pointer.
- From: Martin Galvan <martin dot galvan at tallertechnologies dot com>
- To: Pedro Alves <palves at redhat dot com>
- Cc: gdb-patches <gdb-patches at sourceware dot org>
- Date: Tue, 7 Apr 2015 11:40:49 -0300
- Subject: Re: [PATCH] Fix gdb crash when trying to print the address of a synthetic pointer.
- Authentication-results: sourceware.org; auth=none
- References: <1428415783-15199-1-git-send-email-martin dot galvan at tallertechnologies dot com> <5523EACF dot 2070108 at redhat dot com>
On Tue, Apr 7, 2015 at 11:33 AM, Pedro Alves <palves@redhat.com> wrote:
> Hi Martin,
>
> On 04/07/2015 03:09 PM, Martin Galvan wrote:
>> Trying to print the address of a synthetic pointer (such as a C++ reference after O3 optimization) will cause gdb to crash with the following message:
>>
>> ../gdb/dwarf2loc.c:1625: internal-error: Should not be able to create a lazy value with an enclosing type
>>
>> This patch fixes that by doing a check for synthetic pointers in value_addr and printing an error message.
>>
>> I have a company-wide copyright assignment. I don't have commit access, though, so it would be great if anyone could commit this for me.
>>
>
> Does this pass the testsuite? I seem to recall that the
> TYPE_CODE_REF path below is used by synthetic pointers, but
> I could well be wrong.
For some reason this problem doesn't happen with some synthetic
pointers, such as the "this" pointer in C++ (I assume those are
handled by the TYPE_CODE_REF path). However, I can confirm this
happens with C++ references if optimizing with gcc -O3.
> Could you add some test to cover this? We have some <synthetic
> pointer> tests in gdb.dwarf2/implptr.exp. Maybe add something there?
Ok, will do it.
>> gdb/
>> 2015-04-07 Martin Galvan <martin.galvan@tallertechnologies.com>
>
> Two spaces before and after name.
>
>>
>> * valops.c (value_addr): Don't try to get the address of a synthetic pointer.
>
> Please wrap this at 80 cols.
>
>>
>> ---
>> gdb/valops.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/gdb/valops.c b/gdb/valops.c
>> index 66c63c1..66e2c9d 100644
>> --- a/gdb/valops.c
>> +++ b/gdb/valops.c
>> @@ -1474,6 +1474,13 @@ value_addr (struct value *arg1)
>> struct value *arg2;
>> struct type *type = check_typedef (value_type (arg1));
>>
>> + if (value_bits_synthetic_pointer(arg1, value_embedded_offset (arg1),
>
> Missing space before parens.
>
>> + TARGET_CHAR_BIT * TYPE_LENGTH (type)))
>> + {
>> + error (_("Attempt to take address of a synthetic pointer."));
>> + return NULL;
>
> This "return" is never reached, as "error" throws. Please remove it,
> and then remove the then unnecessary braces.
Will do. Thanks a lot!
--
Martin Galvan
Software Engineer
Taller Technologies Argentina
San Lorenzo 47, 3rd Floor, Office 5
CÃrdoba, Argentina
Phone: 54 351 4217888 / +54 351 4218211