llvm dev - Oct 2016 - RuntimeDyLdCOFF and RTTI on Windows

HI Stefan,

CC'ing Reid Kleckner, who might have some insight here, and llvm-dev as
this may be of interest to other windows JIT users.

I am facing the issue that C++ dynamic_cast doesn't work for
types
> loaded from object files with RuntimeDyLd.

<snip>

Do you think it is possible that RuntimeDyLd misses type info data
in
> the COFF file or doesn't wire it up correctly?
> I set ProcessAllSections = true, but I didn't recognize any change. I
> found that RuntimeDyLdCOFF does not override finalizeLoad like the ELF
> and MachO versions. The function call's comment reads "Give the
> subclasses a chance to tie-up any loose ends" -- possibly missing
> functionality?
>
Unfortunately I don't have a windows machine to test on, so it's
difficult
to know for sure. From a quick look at the IR, it seems like the Window's
C++ ABI implementation of dynamic_cast works similarly to Darwin's: The
type info pointers for the reference type and cast type are passed in to
the function, so as long as memory has been allocated for the type info I
would have expected this to "just work". My best guess for why it
wouldn't
is that RuntimeDyldCOFF is a missing relocation somewhere. What happens
when you run this code on a debug build? Do you hit the llvm_unreachable at
the bottom of the resolveRelocation switch?

Just to rule out one other possibility, Reid: does Windows require any
special calls to register C++ RTTI?

Finally, regarding the ProcessAllSections flag: it tells RuntimeDyld to
call the memory manager interface for every section, not just the sections
that RuntimeDyld thinks are necessary for execution. This was a hack to
make debug info sections visible to clients who are interested in them. It
can be important if your object file contains metadata sections that are
required, but not referenced in the file. I don't think it should affect
this case though.

- Lang.


On Thu, Oct 6, 2016 at 4:37 AM, Stefan Gränitz <stefan.granitz at
roli.com>
wrote:
> Hi Lang
>
> You are not only the maintainer for ORC but also for RuntimeDyLd right?
> May I ask if you know about problems reading RTTI data from COFF object
> files on Windows?
>
> I am facing the issue that C++ dynamic_cast doesn't work for types
> loaded from object files with RuntimeDyLd. I inspected my object files
> compiled with Clang-3.9 (pure, not cl2) and they seem to include all the
> necessary info. When I link (with MS link) and run the static build I
> get the expected behavior. Correspondingly I'd consider the RTTI
> emission in Clang to work correctly.
>
> When I load the object files with RuntimeDyLd at runtime, I face the
> following troubles in vcruntime140.dll:
> * invoking dynamic_cast: the RTTI Complete Object Locator queried in
> __RTDynamicCast (rtti.cpp) has incomplete data, which tricks the runtime
> to always belief the number of base classes is zero, that's why
> dynamic_cast never succeeds
> * invoking typeid(variable).name(): the runtime's __std_type_info_name
> (std_type_info.cpp) receives a corrupt type data pointer, which causes
> an access violation when reading from one of its members
>
> Do you think it is possible that RuntimeDyLd misses type info data in
> the COFF file or doesn't wire it up correctly?
> I set ProcessAllSections = true, but I didn't recognize any change. I
> found that RuntimeDyLdCOFF does not override finalizeLoad like the ELF
> and MachO versions. The function call's comment reads "Give the
> subclasses a chance to tie-up any loose ends" -- possibly missing
> functionality?
>
> It would help a lot if you let me know your feeling on this issue and/or
> give me a few pointers what I could check next.
>
> I can reproduce the above symptoms reliably within our project on
> different Windows systems. I think I can also prepare a self-contained
> repro, if you happen to have a Windows machine/VM at hand and you are
> interested in clearing up this issue.
>
> Thanks.
> Stefan
>
> --
> Stefan Gränitz
> Consultant Software Development JUCE
>
>
> --
>
>
> *ROLI* <http://www.roli.com/>* extends the journey of music creation
to
> everyone. The **acclaimed *
<http://www.roli.com/press/reviews>*Seaboard
> GRAND* <http://www.roli.com/products/seaboard-grand>* and **Seaboard
RISE*
> <http://www.roli.com/products/seaboard-rise>* redefine how expressive
and
> versatile an electronic musical instrument can be. Our groundbreaking
> software **Equator* <http://www.roli.com/equator>* opens up new
dimensions
> of sonic expression, and is built with **JUCE*
<http://www.juce.com/>*,
> ROLI’s proprietary coding platform, and the leading C++ framework for audio
> applications globally. **Blend* <http://www.blend.io/>* enables
everyone
> to
> seamlessly collaborate, share, and remix their music. And **NOISE*
> <http://www.roli.com/noise>* is the most expressive app ever made —
see
> for
> yourself: **download it now for free!
> <https://itunes.apple.com/app/noise-5d/id1011132019?ls=1&mt=8>*
>
>
> Office: +44(0)207 254 2155
>
> *ROLI*
>
> 2 Glebe Road, London E8 4BD
>
> www.roli.com
>
>
>
> Discover more about us on Facebook <http://www.facebook.com/roli> -
> Twitter
> <http://www.twitter.com/weareroli> - Youtube
> <http://www.youtube.com/weareroli>
>
> ROLI Ltd. is a registered company in England and Wales, and this e-mail and
> its attachment(s) are intended for the above named only and are
> confidential. If they have come to you in error then you must take no
> action based upon them but contact us immediately. Any disclosure, copying,
> distribution or any action taken or omitted to be taken in reliance on it
> is prohibited and may be unlawful. Although this e-mail and its attachments
> are believed to be free of any virus, it is the responsibility of the
> recipient to ensure that they are virus free. If you contact us by e-mail
> then we will store your name and address to facilitate communications. Any
> statements contained herein are those of the individual and not the
> organisation.
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20161006/19217e1c/attachment.html>

Thanks Lang for forwarding this to the list
The symptom in a nutshell: I cannot get dynamic_cast to work in JITed
code on Windows

Reid, do you have an idea whether: it's a bug / it's just not
implemented yet / I am missing something?
> Just to rule out one other possibility, Reid: does Windows require any
> special calls to register C++ RTTI?
There's some more details in the original mail.

Thanks
Stefan

Am 07.10.16 um 02:29 schrieb Lang Hames via llvm-dev:
> HI Stefan,
>
> CC'ing Reid Kleckner, who might have some insight here, and llvm-dev
> as this may be of interest to other windows JIT users.
>
>     I am facing the issue that C++ dynamic_cast doesn't work for types
>     loaded from object files with RuntimeDyLd.
>
>  
> <snip>
>
>     Do you think it is possible that RuntimeDyLd misses type info data in
>     the COFF file or doesn't wire it up correctly?
>     I set ProcessAllSections = true, but I didn't recognize any change.
I
>     found that RuntimeDyLdCOFF does not override finalizeLoad like the ELF
>     and MachO versions. The function call's comment reads "Give
the
>     subclasses a chance to tie-up any loose ends" -- possibly missing
>     functionality?
>
>
> Unfortunately I don't have a windows machine to test on, so it's
> difficult to know for sure. From a quick look at the IR, it seems like
> the Window's C++ ABI implementation of dynamic_cast works similarly to
> Darwin's: The type info pointers for the reference type and cast type
> are passed in to the function, so as long as memory has been allocated
> for the type info I would have expected this to "just work". My
best
> guess for why it wouldn't is that RuntimeDyldCOFF is a missing
> relocation somewhere. What happens when you run this code on a debug
> build? Do you hit the llvm_unreachable at the bottom of the
> resolveRelocation switch?
>
> Just to rule out one other possibility, Reid: does Windows require any
> special calls to register C++ RTTI?
>
> Finally, regarding the ProcessAllSections flag: it tells RuntimeDyld
> to call the memory manager interface for every section, not just the
> sections that RuntimeDyld thinks are necessary for execution. This was
> a hack to make debug info sections visible to clients who are
> interested in them. It can be important if your object file contains
> metadata sections that are required, but not referenced in the file. I
> don't think it should affect this case though.
>
> - Lang.
>
>
> On Thu, Oct 6, 2016 at 4:37 AM, Stefan Gränitz
> <stefan.granitz at roli.com <mailto:stefan.granitz at
roli.com>> wrote:
>
>     Hi Lang
>
>     You are not only the maintainer for ORC but also for RuntimeDyLd
>     right?
>     May I ask if you know about problems reading RTTI data from COFF
>     object
>     files on Windows?
>
>     I am facing the issue that C++ dynamic_cast doesn't work for types
>     loaded from object files with RuntimeDyLd. I inspected my object files
>     compiled with Clang-3.9 (pure, not cl2) and they seem to include
>     all the
>     necessary info. When I link (with MS link) and run the static build I
>     get the expected behavior. Correspondingly I'd consider the RTTI
>     emission in Clang to work correctly.
>
>     When I load the object files with RuntimeDyLd at runtime, I face the
>     following troubles in vcruntime140.dll:
>     * invoking dynamic_cast: the RTTI Complete Object Locator queried in
>     __RTDynamicCast (rtti.cpp) has incomplete data, which tricks the
>     runtime
>     to always belief the number of base classes is zero, that's why
>     dynamic_cast never succeeds
>     * invoking typeid(variable).name(): the runtime's
__std_type_info_name
>     (std_type_info.cpp) receives a corrupt type data pointer, which causes
>     an access violation when reading from one of its members
>
>     Do you think it is possible that RuntimeDyLd misses type info data in
>     the COFF file or doesn't wire it up correctly?
>     I set ProcessAllSections = true, but I didn't recognize any change.
I
>     found that RuntimeDyLdCOFF does not override finalizeLoad like the ELF
>     and MachO versions. The function call's comment reads "Give
the
>     subclasses a chance to tie-up any loose ends" -- possibly missing
>     functionality?
>
>     It would help a lot if you let me know your feeling on this issue
>     and/or
>     give me a few pointers what I could check next.
>
>     I can reproduce the above symptoms reliably within our project on
>     different Windows systems. I think I can also prepare a self-contained
>     repro, if you happen to have a Windows machine/VM at hand and you are
>     interested in clearing up this issue.
>
>     Thanks.
>     Stefan
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
-- 
https://about.me/stefan.graenitz

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20161011/1272e4a1/attachment.html>

Hi Lang, hi dev-list (as it may be interesting for others too)

With the cpp file attached, the repro is actually as simple as this:
$ clang -std=c++11 -emit-llvm repro_input.cpp -c -o repro_input.bc
$ lli repro_input.bc

On Mac this prints:
dynamic_cast worked! dummy is 1

On Windows this prints:
dynamic_cast failed

As the issue is reproducible with lli, it's probably unrelated to the
COFF implementation as originally stated.
I built LLVM and Clang from release39 HEAD and used both, clang and lli
from this build. OS versions and CMake flags are:

* OSX 10.10.6 with -DLLVM_ENABLE_RTTI=ON -DLLVM_ENABLE_EH=ON
-DLLVM_TARGETS_TO_BUILD=X86
* Windows 10 64bit OS Build 14393.222 with -DLLVM_ENABLE_RTTI=ON
-DLLVM_ENABLE_EH=ON -DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_USE_CRT_DEBUG=MDd
-DLLVM_USE_CRT_RELEASE=MD

Hope this helps nailing down the issue. Maybe I can help fixing it, if
you can provide a few pointers where to start :) If you need any more
info please let me know.

Cheers
Stefan

Am 19.10.16 um 12:10 schrieb Stefan Gränitz:
> Hi Lang, thanks for getting back to this.
>
>> Did you get a chance to run this on a debug build? Did it trigger an
>> assertions/unreachables? Or did the cast just fail?
> Yes, I use debug builds of Clang and LLVM (both 3.9.1). We have a
> pretty special setup in the Projucer, but with "95% certainty":
> Clang output is correct. Loading the binary objects with RuntimeDyLd
> produces the problem. I spent quite some time debugging this and the
> fact that data is incomplete though it's in the right place feels
> similar to what I experienced with exceptions on Win64 (which turned
> out to be missing registration calls
> https://llvm.org/bugs/show_bug.cgi?id=24233).
>
>> Will you be at the dev meeting? We could take a look at this in one
>> of the labs.
> Sooner or later I will make it to a Bay Area dev meeting, promise!
> Unfortunately not in November as I will be at ADC in London. However,
> I will try to reproduce the issue in a minimal example during our
> Berlin Hackday on Saturday, that's a good challenge! If successful I
> will put it on GitHub and let you know! Maybe you guys then find a
> solution or make a plan at the dev meeting.
>
> Thanks
> Stefan
>
> Am 18.10.16 um 21:35 schrieb Lang Hames:
>> Hi Stefan,
>>
>> Did you get a chance to run this on a debug build? Did it trigger an
>> assertions/unreachables? Or did the cast just fail?
>>
>> Will you be at the dev meeting? We could take a look at this in one
>> of the labs.
>>
>> Cheers,
>> Lang.
>>
>>
>> On Tue, Oct 11, 2016 at 1:52 AM, Stefan Gränitz
>> <stefan.graenitz at gmail.com <mailto:stefan.graenitz at
gmail.com>> wrote:
>>
>>     Thanks Lang for forwarding this to the list
>>     The symptom in a nutshell: I cannot get dynamic_cast to work in
>>     JITed code on Windows
>>
>>     Reid, do you have an idea whether: it's a bug / it's just
not
>>     implemented yet / I am missing something?
>>>     Just to rule out one other possibility, Reid: does Windows
>>>     require any special calls to register C++ RTTI?
>>
>>     There's some more details in the original mail.
>>
>>     Thanks
>>     Stefan
>>
>>     Am 07.10.16 um 02:29 schrieb Lang Hames via llvm-dev:
>>>     HI Stefan,
>>>
>>>     CC'ing Reid Kleckner, who might have some insight here, and
>>>     llvm-dev as this may be of interest to other windows JIT users.
>>>
>>>         I am facing the issue that C++ dynamic_cast doesn't
work for
>>>         types
>>>         loaded from object files with RuntimeDyLd.
>>>
>>>      
>>>     <snip>
>>>
>>>         Do you think it is possible that RuntimeDyLd misses type
>>>         info data in
>>>         the COFF file or doesn't wire it up correctly?
>>>         I set ProcessAllSections = true, but I didn't recognize
any
>>>         change. I
>>>         found that RuntimeDyLdCOFF does not override finalizeLoad
>>>         like the ELF
>>>         and MachO versions. The function call's comment reads
"Give the
>>>         subclasses a chance to tie-up any loose ends" --
possibly
>>>         missing
>>>         functionality?
>>>
>>>
>>>     Unfortunately I don't have a windows machine to test on, so
it's
>>>     difficult to know for sure. From a quick look at the IR, it
>>>     seems like the Window's C++ ABI implementation of
dynamic_cast
>>>     works similarly to Darwin's: The type info pointers for the
>>>     reference type and cast type are passed in to the function, so
>>>     as long as memory has been allocated for the type info I would
>>>     have expected this to "just work". My best guess for
why it
>>>     wouldn't is that RuntimeDyldCOFF is a missing relocation
>>>     somewhere. What happens when you run this code on a debug
build?
>>>     Do you hit the llvm_unreachable at the bottom of the
>>>     resolveRelocation switch?
>>>
>>>     Just to rule out one other possibility, Reid: does Windows
>>>     require any special calls to register C++ RTTI?
>>>
>>>     Finally, regarding the ProcessAllSections flag: it tells
>>>     RuntimeDyld to call the memory manager interface for every
>>>     section, not just the sections that RuntimeDyld thinks are
>>>     necessary for execution. This was a hack to make debug info
>>>     sections visible to clients who are interested in them. It can
>>>     be important if your object file contains metadata sections
that
>>>     are required, but not referenced in the file. I don't think
it
>>>     should affect this case though.
>>>
>>>     - Lang.
>>>
>>>
>>>     On Thu, Oct 6, 2016 at 4:37 AM, Stefan Gränitz
>>>     <stefan.granitz at roli.com <mailto:stefan.granitz at
roli.com>> wrote:
>>>
>>>         Hi Lang
>>>
>>>         You are not only the maintainer for ORC but also for
>>>         RuntimeDyLd right?
>>>         May I ask if you know about problems reading RTTI data from
>>>         COFF object
>>>         files on Windows?
>>>
>>>         I am facing the issue that C++ dynamic_cast doesn't
work for
>>>         types
>>>         loaded from object files with RuntimeDyLd. I inspected my
>>>         object files
>>>         compiled with Clang-3.9 (pure, not cl2) and they seem to
>>>         include all the
>>>         necessary info. When I link (with MS link) and run the
>>>         static build I
>>>         get the expected behavior. Correspondingly I'd consider
the RTTI
>>>         emission in Clang to work correctly.
>>>
>>>         When I load the object files with RuntimeDyLd at runtime, I
>>>         face the
>>>         following troubles in vcruntime140.dll:
>>>         * invoking dynamic_cast: the RTTI Complete Object Locator
>>>         queried in
>>>         __RTDynamicCast (rtti.cpp) has incomplete data, which
tricks
>>>         the runtime
>>>         to always belief the number of base classes is zero,
that's why
>>>         dynamic_cast never succeeds
>>>         * invoking typeid(variable).name(): the runtime's
>>>         __std_type_info_name
>>>         (std_type_info.cpp) receives a corrupt type data pointer,
>>>         which causes
>>>         an access violation when reading from one of its members
>>>
>>>         Do you think it is possible that RuntimeDyLd misses type
>>>         info data in
>>>         the COFF file or doesn't wire it up correctly?
>>>         I set ProcessAllSections = true, but I didn't recognize
any
>>>         change. I
>>>         found that RuntimeDyLdCOFF does not override finalizeLoad
>>>         like the ELF
>>>         and MachO versions. The function call's comment reads
"Give the
>>>         subclasses a chance to tie-up any loose ends" --
possibly
>>>         missing
>>>         functionality?
>>>
>>>         It would help a lot if you let me know your feeling on this
>>>         issue and/or
>>>         give me a few pointers what I could check next.
>>>
>>>         I can reproduce the above symptoms reliably within our
>>>         project on
>>>         different Windows systems. I think I can also prepare a
>>>         self-contained
>>>         repro, if you happen to have a Windows machine/VM at hand
>>>         and you are
>>>         interested in clearing up this issue.
>>>
>>>         Thanks.
>>>         Stefan
>>>
>>>     _______________________________________________
>>>     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
>>>     <http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
>>
>>     -- 
>>     https://about.me/stefan.graenitz
<https://about.me/stefan.graenitz>
>>
> -- 
> https://about.me/stefan.graenitz
-- 
https://about.me/stefan.graenitz
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20161022/a2adf2f2/attachment.html>
-------------- next part --------------
#include "stdio.h"

class MyBase {
public:
  MyBase(int dummyValue) : dummyMember(dummyValue) {}
  virtual ~MyBase() {}

protected:
  int dummyMember;
};

class MyDerived : public MyBase {
public:
  MyDerived(int dummyValue) : MyBase(dummyValue) {}
  int getDummy() { return dummyMember; }
};

int main(int argc, char** argv) {
  MyBase* myBasePtr;

  if (argc > 0)
    myBasePtr = new MyDerived(1);
  else
    myBasePtr = new MyBase(2); // avoid opt, but actually never happens

  if (auto p = dynamic_cast<MyDerived*>(myBasePtr)) {
    printf ("dynamic_cast worked! dummy is %d\n", p->getDummy());
  }
  else {
    printf ("dynamic_cast failed");
  }

  return 0;  
}

I have a similar build tree to what you describe on Windows, but I get this:

$ clang -c -emit-llvm repro_input.cpp -std=c++11 -o t.bc
$ lli t.bc
LLVM ERROR: Program used external function '??_7type_info@@6B@' which
could
not be resolved!

It looks like people have already reported similar issues. Have you done
anything to get past this kind of problem?

On Sat, Oct 22, 2016 at 7:18 AM, Stefan Gränitz via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi Lang, hi dev-list (as it may be interesting for others too)
>
> With the cpp file attached, the repro is actually as simple as this:
> $ clang -std=c++11 -emit-llvm repro_input.cpp -c -o repro_input.bc
> $ lli repro_input.bc
>
> On Mac this prints:
> dynamic_cast worked! dummy is 1
>
> On Windows this prints:
> dynamic_cast failed
>
> As the issue is reproducible with lli, it's probably unrelated to the
COFF
> implementation as originally stated.
> I built LLVM and Clang from release39 HEAD and used both, clang and lli
> from this build. OS versions and CMake flags are:
>
> * OSX 10.10.6 with -DLLVM_ENABLE_RTTI=ON -DLLVM_ENABLE_EH=ON
> -DLLVM_TARGETS_TO_BUILD=X86
> * Windows 10 64bit OS Build 14393.222 with -DLLVM_ENABLE_RTTI=ON
> -DLLVM_ENABLE_EH=ON -DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_USE_CRT_DEBUG=MDd
> -DLLVM_USE_CRT_RELEASE=MD
>
> Hope this helps nailing down the issue. Maybe I can help fixing it, if you
> can provide a few pointers where to start :) If you need any more info
> please let me know.
>
> Cheers
> Stefan
>
> Am 19.10.16 um 12:10 schrieb Stefan Gränitz:
>
> Hi Lang, thanks for getting back to this.
>
> Did you get a chance to run this on a debug build? Did it trigger an
> assertions/unreachables? Or did the cast just fail?
>
> Yes, I use debug builds of Clang and LLVM (both 3.9.1). We have a pretty
> special setup in the Projucer, but with "95% certainty":
> Clang output is correct. Loading the binary objects with RuntimeDyLd
> produces the problem. I spent quite some time debugging this and the fact
> that data is incomplete though it's in the right place feels similar to
> what I experienced with exceptions on Win64 (which turned out to be missing
> registration calls https://llvm.org/bugs/show_bug.cgi?id=24233).
>
> Will you be at the dev meeting? We could take a look at this in one of the
> labs.
>
> Sooner or later I will make it to a Bay Area dev meeting, promise!
> Unfortunately not in November as I will be at ADC in London. However, I
> will try to reproduce the issue in a minimal example during our Berlin
> Hackday on Saturday, that's a good challenge! If successful I will put
it
> on GitHub and let you know! Maybe you guys then find a solution or make a
> plan at the dev meeting.
>
> Thanks
> Stefan
>
> Am 18.10.16 um 21:35 schrieb Lang Hames:
>
> Hi Stefan,
>
> Did you get a chance to run this on a debug build? Did it trigger an
> assertions/unreachables? Or did the cast just fail?
>
> Will you be at the dev meeting? We could take a look at this in one of the
> labs.
>
> Cheers,
> Lang.
>
>
> On Tue, Oct 11, 2016 at 1:52 AM, Stefan Gränitz <stefan.graenitz at
gmail.com
> > wrote:
>
>> Thanks Lang for forwarding this to the list
>> The symptom in a nutshell: I cannot get dynamic_cast to work in JITed
>> code on Windows
>>
>> Reid, do you have an idea whether: it's a bug / it's just not
implemented
>> yet / I am missing something?
>>
>> Just to rule out one other possibility, Reid: does Windows require any
>> special calls to register C++ RTTI?
>>
>>
>> There's some more details in the original mail.
>>
>> Thanks
>> Stefan
>>
>> Am 07.10.16 um 02:29 schrieb Lang Hames via llvm-dev:
>>
>> HI Stefan,
>>
>> CC'ing Reid Kleckner, who might have some insight here, and
llvm-dev as
>> this may be of interest to other windows JIT users.
>>
>> I am facing the issue that C++ dynamic_cast doesn't work for types
>>> loaded from object files with RuntimeDyLd.
>>
>>
>> <snip>
>>
>> Do you think it is possible that RuntimeDyLd misses type info data in
>>> the COFF file or doesn't wire it up correctly?
>>> I set ProcessAllSections = true, but I didn't recognize any
change. I
>>> found that RuntimeDyLdCOFF does not override finalizeLoad like the
ELF
>>> and MachO versions. The function call's comment reads
"Give the
>>> subclasses a chance to tie-up any loose ends" -- possibly
missing
>>> functionality?
>>>
>>
>> Unfortunately I don't have a windows machine to test on, so
it's
>> difficult to know for sure. From a quick look at the IR, it seems like
the
>> Window's C++ ABI implementation of dynamic_cast works similarly to
>> Darwin's: The type info pointers for the reference type and cast
type are
>> passed in to the function, so as long as memory has been allocated for
the
>> type info I would have expected this to "just work". My best
guess for why
>> it wouldn't is that RuntimeDyldCOFF is a missing relocation
somewhere. What
>> happens when you run this code on a debug build? Do you hit the
>> llvm_unreachable at the bottom of the resolveRelocation switch?
>>
>> Just to rule out one other possibility, Reid: does Windows require any
>> special calls to register C++ RTTI?
>>
>> Finally, regarding the ProcessAllSections flag: it tells RuntimeDyld to
>> call the memory manager interface for every section, not just the
sections
>> that RuntimeDyld thinks are necessary for execution. This was a hack to
>> make debug info sections visible to clients who are interested in them.
It
>> can be important if your object file contains metadata sections that
are
>> required, but not referenced in the file. I don't think it should
affect
>> this case though.
>>
>> - Lang.
>>
>>
>> On Thu, Oct 6, 2016 at 4:37 AM, Stefan Gränitz <stefan.granitz at
roli.com>
>> wrote:
>>
>>> Hi Lang
>>>
>>> You are not only the maintainer for ORC but also for RuntimeDyLd
right?
>>> May I ask if you know about problems reading RTTI data from COFF
object
>>> files on Windows?
>>>
>>> I am facing the issue that C++ dynamic_cast doesn't work for
types
>>> loaded from object files with RuntimeDyLd. I inspected my object
files
>>> compiled with Clang-3.9 (pure, not cl2) and they seem to include
all the
>>> necessary info. When I link (with MS link) and run the static build
I
>>> get the expected behavior. Correspondingly I'd consider the
RTTI
>>> emission in Clang to work correctly.
>>>
>>> When I load the object files with RuntimeDyLd at runtime, I face
the
>>> following troubles in vcruntime140.dll:
>>> * invoking dynamic_cast: the RTTI Complete Object Locator queried
in
>>> __RTDynamicCast (rtti.cpp) has incomplete data, which tricks the
runtime
>>> to always belief the number of base classes is zero, that's why
>>> dynamic_cast never succeeds
>>> * invoking typeid(variable).name(): the runtime's
__std_type_info_name
>>> (std_type_info.cpp) receives a corrupt type data pointer, which
causes
>>> an access violation when reading from one of its members
>>>
>>> Do you think it is possible that RuntimeDyLd misses type info data
in
>>> the COFF file or doesn't wire it up correctly?
>>> I set ProcessAllSections = true, but I didn't recognize any
change. I
>>> found that RuntimeDyLdCOFF does not override finalizeLoad like the
ELF
>>> and MachO versions. The function call's comment reads
"Give the
>>> subclasses a chance to tie-up any loose ends" -- possibly
missing
>>> functionality?
>>>
>>> It would help a lot if you let me know your feeling on this issue
and/or
>>> give me a few pointers what I could check next.
>>>
>>> I can reproduce the above symptoms reliably within our project on
>>> different Windows systems. I think I can also prepare a
self-contained
>>> repro, if you happen to have a Windows machine/VM at hand and you
are
>>> interested in clearing up this issue.
>>>
>>> Thanks.
>>> Stefan
>>>
>> _______________________________________________
>> LLVM Developers mailing listllvm-dev at
lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>> -- https://about.me/stefan.graenitz
>>
>> -- https://about.me/stefan.graenitz
>
> -- https://about.me/stefan.graenitz
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20161024/730d9553/attachment.html>