* Two debug entries for one local variables, is it a bug in GCC or GDB
@ 2010-07-09 2:35 asmwarrior
2010-07-09 5:58 ` Nenad Vukicevic
0 siblings, 1 reply; 4+ messages in thread
From: asmwarrior @ 2010-07-09 2:35 UTC (permalink / raw)
To: gdb, gcc
I have post this message to both GCC and GDB, because I'm not sure it
is a bug in GDB or GCC.
Hi, I have just find two dwarf debug entries for one local variables.
For example, the sample code is just like:
-----------------------------------------
wxString ParserThread::ReadAncestorList()
{
wxString ccc;
wxString templateArgument;
wxString aaa;
aaa = m_Tokenizer.GetToken(); // eat ":"
templateArgument = aaa;
while (!TestDestroy())
{
//Peek the next token
wxString next = m_Tokenizer.PeekToken();
if (next.IsEmpty()
|| next==ParserConsts::opbrace
|| next==ParserConsts::semicolon ) // here, we are at the end of ancestor list
{
break;
}
else if (next==ParserConsts::lt) // class AAA : BBB< int, float>
{
wxString arg = SkipAngleBraces();
if(!arg.IsEmpty()) // find a matching<>
{
templateArgument<<arg;
}
else
{
TRACE(_T("Not Matching<> find. Error!!!") );
}
}
...
-------------------------------------------
But I found that GDG can show the wxString aaa correctly, but wxString templateArgument incorrectly.
I have just check the debug information in the object file.
and found that there are two entries for local variable "argumentTemplate", but only one entry for "aaa".
--------------------------------------------
<2><40a9f>: Abbrev Number: 182 (DW_TAG_variable)
<40aa1> DW_AT_name : (indirect string, offset: 0x1095): templateArgument
<40aa5> DW_AT_decl_file : 19
<40aa6> DW_AT_decl_line : 2593
<40aa8> DW_AT_type :<0xd168>
<40aac> DW_AT_accessibility: 3 (private)
<40aad> DW_AT_location : 2 byte block: 53 6 (DW_OP_reg3; DW_OP_deref)
<2><40ab0>: Abbrev Number: 164 (DW_TAG_lexical_block)
<40ab2> DW_AT_ranges : 0x168
<3><40ab6>: Abbrev Number: 165 (DW_TAG_variable)
<40ab8> DW_AT_name : ccc
<40abc> DW_AT_decl_file : 19
<40abd> DW_AT_decl_line : 2592
<40abf> DW_AT_type :<0xd168>
<40ac3> DW_AT_location : 2 byte block: 91 50 (DW_OP_fbreg: -48)
<3><40ac6>: Abbrev Number: 179 (DW_TAG_variable)
<40ac8> DW_AT_name : (indirect string, offset: 0x1095): templateArgument
<40acc> DW_AT_decl_file : 19
<40acd> DW_AT_decl_line : 2593
<40acf> DW_AT_type :<0xd168>
<40ad3> DW_AT_location : 2 byte block: 91 4c (DW_OP_fbreg: -52)
<3><40ad6>: Abbrev Number: 165 (DW_TAG_variable)
<40ad8> DW_AT_name : aaa
<40adc> DW_AT_decl_file : 19
<40add> DW_AT_decl_line : 2594
<40adf> DW_AT_type :<0xd168>
<40ae3> DW_AT_location : 2 byte block: 91 48 (DW_OP_fbreg: -56)
<3><40ae6>: Abbrev Number: 170 (DW_TAG_lexical_block)
------------------------------------------------------------------------------
Also, you can see the screen shot in my Codeblocks forums' post:
http://forums.codeblocks.org/index.php/topic,12873.msg86906.html#msg86906
So, my question is:
Is this a bug in GCC or GDB? ( I have just test the MinGW GCC 4.5 and MinGW 4.4.4, they get the same result)
Thanks
Asmwarrior (ollydbg from codeblocks' forum)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Two debug entries for one local variables, is it a bug in GCC or GDB
2010-07-09 2:35 Two debug entries for one local variables, is it a bug in GCC or GDB asmwarrior
@ 2010-07-09 5:58 ` Nenad Vukicevic
2010-07-09 6:04 ` asmwarrior
2010-07-10 4:09 ` Daniel Berlin
0 siblings, 2 replies; 4+ messages in thread
From: Nenad Vukicevic @ 2010-07-09 5:58 UTC (permalink / raw)
To: asmwarrior; +Cc: gdb, gcc
I reported something similar back in January:
http://gcc.gnu.org/ml/gcc/2010-01/msg00054.html
As I recall, GCC creates duplicates.
Nenad
On 7/8/10 7:33 PM, asmwarrior wrote:
> I have post this message to both GCC and GDB, because I'm not sure it
> is a bug in GDB or GCC.
> Hi, I have just find two dwarf debug entries for one local variables.
>
> For example, the sample code is just like:
>
> -----------------------------------------
>
> wxString ParserThread::ReadAncestorList()
> {
>
> wxString ccc;
> wxString templateArgument;
> wxString aaa;
> aaa = m_Tokenizer.GetToken(); // eat ":"
> templateArgument = aaa;
> while (!TestDestroy())
> {
>
> //Peek the next token
> wxString next = m_Tokenizer.PeekToken();
>
> if (next.IsEmpty()
> || next==ParserConsts::opbrace
> || next==ParserConsts::semicolon ) // here, we are at the
> end of ancestor list
> {
> break;
> }
> else if (next==ParserConsts::lt) // class AAA : BBB<
> int, float>
> {
> wxString arg = SkipAngleBraces();
> if(!arg.IsEmpty()) // find a matching<>
> {
> templateArgument<<arg;
> }
> else
> {
> TRACE(_T("Not Matching<> find. Error!!!") );
> }
> }
> ...
> -------------------------------------------
>
> But I found that GDG can show the wxString aaa correctly, but wxString
> templateArgument incorrectly.
>
> I have just check the debug information in the object file.
> and found that there are two entries for local variable
> "argumentTemplate", but only one entry for "aaa".
>
> --------------------------------------------
> <2><40a9f>: Abbrev Number: 182 (DW_TAG_variable)
> <40aa1> DW_AT_name : (indirect string, offset: 0x1095):
> templateArgument
> <40aa5> DW_AT_decl_file : 19
> <40aa6> DW_AT_decl_line : 2593
> <40aa8> DW_AT_type :<0xd168>
> <40aac> DW_AT_accessibility: 3 (private)
> <40aad> DW_AT_location : 2 byte block: 53 6 (DW_OP_reg3;
> DW_OP_deref)
> <2><40ab0>: Abbrev Number: 164 (DW_TAG_lexical_block)
> <40ab2> DW_AT_ranges : 0x168
> <3><40ab6>: Abbrev Number: 165 (DW_TAG_variable)
> <40ab8> DW_AT_name : ccc
> <40abc> DW_AT_decl_file : 19
> <40abd> DW_AT_decl_line : 2592
> <40abf> DW_AT_type :<0xd168>
> <40ac3> DW_AT_location : 2 byte block: 91 50 (DW_OP_fbreg: -48)
> <3><40ac6>: Abbrev Number: 179 (DW_TAG_variable)
> <40ac8> DW_AT_name : (indirect string, offset: 0x1095):
> templateArgument
> <40acc> DW_AT_decl_file : 19
> <40acd> DW_AT_decl_line : 2593
> <40acf> DW_AT_type :<0xd168>
> <40ad3> DW_AT_location : 2 byte block: 91 4c (DW_OP_fbreg: -52)
> <3><40ad6>: Abbrev Number: 165 (DW_TAG_variable)
> <40ad8> DW_AT_name : aaa
> <40adc> DW_AT_decl_file : 19
> <40add> DW_AT_decl_line : 2594
> <40adf> DW_AT_type :<0xd168>
> <40ae3> DW_AT_location : 2 byte block: 91 48 (DW_OP_fbreg: -56)
> <3><40ae6>: Abbrev Number: 170 (DW_TAG_lexical_block)
>
> ------------------------------------------------------------------------------
>
> Also, you can see the screen shot in my Codeblocks forums' post:
>
> http://forums.codeblocks.org/index.php/topic,12873.msg86906.html#msg86906
>
>
> So, my question is:
>
> Is this a bug in GCC or GDB? ( I have just test the MinGW GCC 4.5 and
> MinGW 4.4.4, they get the same result)
>
>
> Thanks
>
> Asmwarrior (ollydbg from codeblocks' forum)
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Two debug entries for one local variables, is it a bug in GCC or GDB
2010-07-09 5:58 ` Nenad Vukicevic
@ 2010-07-09 6:04 ` asmwarrior
2010-07-10 4:09 ` Daniel Berlin
1 sibling, 0 replies; 4+ messages in thread
From: asmwarrior @ 2010-07-09 6:04 UTC (permalink / raw)
To: Nenad Vukicevic; +Cc: gdb, gcc
On 2010-7-9 13:58, Nenad Vukicevic wrote:
> I reported something similar back in January:
>
> http://gcc.gnu.org/ml/gcc/2010-01/msg00054.html
>
> As I recall, GCC creates duplicates.
>
> Nenad
Thanks for the reply. I also found your message,
This bug has been fixed,see:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39563
You bug report is related to global variables.
My problem is related to a auto variables. Especially the variable will
be returned.
Something like:
T foo()
{
T a;
T b;
T c;
...
return b;
}
then, the unreturned variable "a" and "c" works well.
But the returned variable "b" will have two debug information entries.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Two debug entries for one local variables, is it a bug in GCC or GDB
2010-07-09 5:58 ` Nenad Vukicevic
2010-07-09 6:04 ` asmwarrior
@ 2010-07-10 4:09 ` Daniel Berlin
1 sibling, 0 replies; 4+ messages in thread
From: Daniel Berlin @ 2010-07-10 4:09 UTC (permalink / raw)
To: Nenad Vukicevic; +Cc: asmwarrior, gdb, gcc
Your bug was not a real bug, AFAICT.
At least the debug info you have shown in
http://gcc.gnu.org/ml/gcc/2010-01/msg00054.html is not wrong.
Certainly, two DIES were unnecessary, but the way it did it was not broken.
Note that one of them is marked as DW_AT_declaration, specifying that
is where the declaration of that variable occurred.
The other is a definition.
They happen to be at the same line, so it's pointless to create two
DIE's, but it's not broken.
In this case, the debug information asmwarrior is showing is clearly broken.
I suspect GCC is splitting the variable somehow, because if you
notice, templateArgument is given different memory locations in both
blocks.
On Fri, Jul 9, 2010 at 1:58 AM, Nenad Vukicevic <nenad@intrepid.com> wrote:
> I reported something similar back in January:
>
> http://gcc.gnu.org/ml/gcc/2010-01/msg00054.html
>
> As I recall, GCC creates duplicates.
>
> Nenad
>
> On 7/8/10 7:33 PM, asmwarrior wrote:
>>
>> I have post this message to both GCC and GDB, because I'm not sure it is
>> a bug in GDB or GCC.
>> Hi, I have just find two dwarf debug entries for one local variables.
>>
>> For example, the sample code is just like:
>>
>> -----------------------------------------
>>
>> wxString ParserThread::ReadAncestorList()
>> {
>>
>> wxString ccc;
>> wxString templateArgument;
>> wxString aaa;
>> aaa = m_Tokenizer.GetToken(); // eat ":"
>> templateArgument = aaa;
>> while (!TestDestroy())
>> {
>>
>> //Peek the next token
>> wxString next = m_Tokenizer.PeekToken();
>>
>> if (next.IsEmpty()
>> || next==ParserConsts::opbrace
>> || next==ParserConsts::semicolon ) // here, we are at the end
>> of ancestor list
>> {
>> break;
>> }
>> else if (next==ParserConsts::lt) // class AAA : BBB< int,
>> float>
>> {
>> wxString arg = SkipAngleBraces();
>> if(!arg.IsEmpty()) // find a matching<>
>> {
>> templateArgument<<arg;
>> }
>> else
>> {
>> TRACE(_T("Not Matching<> find. Error!!!") );
>> }
>> }
>> ...
>> -------------------------------------------
>>
>> But I found that GDG can show the wxString aaa correctly, but wxString
>> templateArgument incorrectly.
>>
>> I have just check the debug information in the object file.
>> and found that there are two entries for local variable
>> "argumentTemplate", but only one entry for "aaa".
>>
>> --------------------------------------------
>> <2><40a9f>: Abbrev Number: 182 (DW_TAG_variable)
>> <40aa1> DW_AT_name : (indirect string, offset: 0x1095):
>> templateArgument
>> <40aa5> DW_AT_decl_file : 19
>> <40aa6> DW_AT_decl_line : 2593
>> <40aa8> DW_AT_type :<0xd168>
>> <40aac> DW_AT_accessibility: 3 (private)
>> <40aad> DW_AT_location : 2 byte block: 53 6 (DW_OP_reg3;
>> DW_OP_deref)
>> <2><40ab0>: Abbrev Number: 164 (DW_TAG_lexical_block)
>> <40ab2> DW_AT_ranges : 0x168
>> <3><40ab6>: Abbrev Number: 165 (DW_TAG_variable)
>> <40ab8> DW_AT_name : ccc
>> <40abc> DW_AT_decl_file : 19
>> <40abd> DW_AT_decl_line : 2592
>> <40abf> DW_AT_type :<0xd168>
>> <40ac3> DW_AT_location : 2 byte block: 91 50 (DW_OP_fbreg: -48)
>> <3><40ac6>: Abbrev Number: 179 (DW_TAG_variable)
>> <40ac8> DW_AT_name : (indirect string, offset: 0x1095):
>> templateArgument
>> <40acc> DW_AT_decl_file : 19
>> <40acd> DW_AT_decl_line : 2593
>> <40acf> DW_AT_type :<0xd168>
>> <40ad3> DW_AT_location : 2 byte block: 91 4c (DW_OP_fbreg: -52)
>> <3><40ad6>: Abbrev Number: 165 (DW_TAG_variable)
>> <40ad8> DW_AT_name : aaa
>> <40adc> DW_AT_decl_file : 19
>> <40add> DW_AT_decl_line : 2594
>> <40adf> DW_AT_type :<0xd168>
>> <40ae3> DW_AT_location : 2 byte block: 91 48 (DW_OP_fbreg: -56)
>> <3><40ae6>: Abbrev Number: 170 (DW_TAG_lexical_block)
>>
>>
>> ------------------------------------------------------------------------------
>> Also, you can see the screen shot in my Codeblocks forums' post:
>>
>> http://forums.codeblocks.org/index.php/topic,12873.msg86906.html#msg86906
>>
>>
>> So, my question is:
>>
>> Is this a bug in GCC or GDB? ( I have just test the MinGW GCC 4.5 and
>> MinGW 4.4.4, they get the same result)
>>
>>
>> Thanks
>>
>> Asmwarrior (ollydbg from codeblocks' forum)
>>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2010-07-10 4:09 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2010-07-09 2:35 Two debug entries for one local variables, is it a bug in GCC or GDB asmwarrior
2010-07-09 5:58 ` Nenad Vukicevic
2010-07-09 6:04 ` asmwarrior
2010-07-10 4:09 ` Daniel Berlin
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox