* [PATCH] Fix gdb crash when trying to print the address of a synthetic pointer.
@ 2015-04-07 14:09 Martin Galvan
2015-04-07 14:33 ` Pedro Alves
0 siblings, 1 reply; 3+ messages in thread
From: Martin Galvan @ 2015-04-07 14:09 UTC (permalink / raw)
To: gdb-patches
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.
gdb/
2015-04-07 Martin Galvan <martin.galvan@tallertechnologies.com>
* valops.c (value_addr): Don't try to get the address of a synthetic pointer.
---
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),
+ TARGET_CHAR_BIT * TYPE_LENGTH (type)))
+ {
+ error (_("Attempt to take address of a synthetic pointer."));
+ return NULL;
+ }
+
if (TYPE_CODE (type) == TYPE_CODE_REF)
{
/* Copy the value, but change the type from (T&) to (T*). We
--
2.3.5
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Fix gdb crash when trying to print the address of a synthetic pointer.
2015-04-07 14:09 [PATCH] Fix gdb crash when trying to print the address of a synthetic pointer Martin Galvan
@ 2015-04-07 14:33 ` Pedro Alves
2015-04-07 14:41 ` Martin Galvan
0 siblings, 1 reply; 3+ messages in thread
From: Pedro Alves @ 2015-04-07 14:33 UTC (permalink / raw)
To: Martin Galvan, gdb-patches
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.
Could you add some test to cover this? We have some <synthetic
pointer> tests in gdb.dwarf2/implptr.exp. Maybe add something there?
> 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.
Thanks,
Pedro Alves
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Fix gdb crash when trying to print the address of a synthetic pointer.
2015-04-07 14:33 ` Pedro Alves
@ 2015-04-07 14:41 ` Martin Galvan
0 siblings, 0 replies; 3+ messages in thread
From: Martin Galvan @ 2015-04-07 14:41 UTC (permalink / raw)
To: Pedro Alves; +Cc: gdb-patches
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
Córdoba, Argentina
Phone: 54 351 4217888 / +54 351 4218211
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-04-07 14:09 [PATCH] Fix gdb crash when trying to print the address of a synthetic pointer Martin Galvan
2015-04-07 14:33 ` Pedro Alves
2015-04-07 14:41 ` Martin Galvan
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