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Reid Kleckner via llvm-dev

2018-Jan-17 17:29 UTC

[llvm-dev] Dumping debug information from BC files

The debug information is actually still in a different format in the .bc
file, it is LLVM metadata. I think the best reference for it is here:
https://llvm.org/docs/SourceLevelDebugging.html#ccxx-frontend

You can dump it just by disassembling the .bc file to textual IR using
llvm-dis and examining the !DI* metadata nodes. You will have to run the
file through llc to generate an object file to generate actual CodeView or
DWARF.

On Wed, Jan 17, 2018 at 5:09 AM, 陳韋任 via llvm-dev <llvm-dev at
lists.llvm.org>
wrote:
> 3.) Then I used clang-cl to generate a .bc file - but now I'm not able
to
>> use "llvm-readobj" anymore. Is there any tool available which
can dump this
>> debug information too?
>>
>
> .bc is LLVM bitcode [1], not the usual object file. `llvm-readobj` should
> works only on the latter.
>
> [1] https://llvm.org/docs/BitCodeFormat.html
>
> --
> Wei-Ren Chen (陳韋任)
> Homepage: https://people.cs.nctu.edu.tw/~chenwj
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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via llvm-dev

2018-Jan-18 08:04 UTC

head link

[llvm-dev] Dumping debug information from BC files

Thank you for your reply.

When I'm running "llvm-readobj" on an .obj file I get a result
like shown
in my attachment. This is very easy to read. I don't know if this is the 
codeview format. I would like to get this kind of debug information form a 
.bc file too, because I JIT them and wanted to try to build a debugger. 
With the file from "llvm-readobj" I see no problem - but when using
the
metadata I have no clue how to find variables on the stack - there are 
only this intrinsics, but I don't know how to handle them. 
Maybe I asked the wrong question :/



From:   Reid Kleckner <rnk at google.com>
To:     陳韋任 <chenwj.cs97g at g2.nctu.edu.tw>
Cc:     bjoern.gaier at horiba.com, LLVM Developers Mailing List 
<llvm-dev at lists.llvm.org>
Date:   17.01.2018 18:29
Subject:        Re: [llvm-dev] Dumping debug information from BC files



The debug information is actually still in a different format in the .bc 
file, it is LLVM metadata. I think the best reference for it is here: 
https://llvm.org/docs/SourceLevelDebugging.html#ccxx-frontend

You can dump it just by disassembling the .bc file to textual IR using 
llvm-dis and examining the !DI* metadata nodes. You will have to run the 
file through llc to generate an object file to generate actual CodeView or 
DWARF.

On Wed, Jan 17, 2018 at 5:09 AM, 陳韋任 via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
3.) Then I used clang-cl to generate a .bc file - but now I'm not able to 
use "llvm-readobj" anymore. Is there any tool available which can dump
this debug information too? 

.bc is LLVM bitcode [1], not the usual object file. `llvm-readobj` 
should works only on the latter.

[1] https://llvm.org/docs/BitCodeFormat.html

-- 
Wei-Ren Chen (陳韋任)
Homepage: https://people.cs.nctu.edu.tw/~chenwj

_______________________________________________
LLVM Developers mailing list
llvm-dev at lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev




Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816, 
USt.ID-Nr. DE 114 165 789
Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert Plank, Markus Bode, 
Heiko Lampert, Hiroshi Kawamura, Takashi Nagano, Takeshi Fukushima.


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Robinson, Paul via llvm-dev

2018-Jan-18 19:39 UTC

head link

[llvm-dev] Dumping debug information from BC files

A .bc file contains a form of LLVM IR (internal representation), it does not
contain machine code.  You cannot use debug information in IR to find variables
on the stack, because variables have not been assigned stack locations or
registers until after you finish compiling or JIT the IR.
The JIT will translate IR instructions to machine instructions, assigning stack
locations and so forth as it does so.  I don't know whether the JIT also
translates the IR debug info into DWARF or CodeView, but that would be the kind
of translation you need in order to debug the code produced by the JIT.
--paulr

From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of via
llvm-dev
Sent: Thursday, January 18, 2018 12:04 AM
To: Reid Kleckner
Cc: LLVM Developers Mailing List
Subject: Re: [llvm-dev] Dumping debug information from BC files

Thank you for your reply.

When I'm running "llvm-readobj" on an .obj file I get a result
like shown in my attachment. This is very easy to read. I don't know if this
is the codeview format. I would like to get this kind of debug information form
a .bc file too, because I JIT them and wanted to try to build a debugger. With
the file from "llvm-readobj" I see no problem - but when using the
metadata I have no clue how to find variables on the stack - there are only this
intrinsics, but I don't know how to handle them.
Maybe I asked the wrong question :/



From:        Reid Kleckner <rnk at google.com<mailto:rnk at
google.com>>
To:        陳韋任 <chenwj.cs97g at g2.nctu.edu.tw<mailto:chenwj.cs97g at
g2.nctu.edu.tw>>
Cc:        bjoern.gaier at horiba.com<mailto:bjoern.gaier at horiba.com>,
LLVM Developers Mailing List <llvm-dev at lists.llvm.org<mailto:llvm-dev
at lists.llvm.org>>
Date:        17.01.2018 18:29
Subject:        Re: [llvm-dev] Dumping debug information from BC files
________________________________



The debug information is actually still in a different format in the .bc file,
it is LLVM metadata. I think the best reference for it is here:
https://llvm.org/docs/SourceLevelDebugging.html#ccxx-frontend

You can dump it just by disassembling the .bc file to textual IR using llvm-dis
and examining the !DI* metadata nodes. You will have to run the file through llc
to generate an object file to generate actual CodeView or DWARF.

On Wed, Jan 17, 2018 at 5:09 AM, 陳韋任 via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:
3.) Then I used clang-cl to generate a .bc file - but now I'm not able to
use "llvm-readobj" anymore. Is there any tool available which can dump
this debug information too?

.bc is LLVM bitcode [1], not the usual object file. `llvm-readobj` should works
only on the latter.

[1] https://llvm.org/docs/BitCodeFormat.html

--
Wei-Ren Chen (陳韋任)
Homepage: https://people.cs.nctu.edu.tw/~chenwj

_______________________________________________
LLVM Developers mailing list
llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev




Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816, USt.ID-Nr.
DE 114 165 789
Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert Plank, Markus Bode, Heiko
Lampert, Hiroshi Kawamura, Takashi Nagano, Takeshi Fukushima.
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