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Martell Malone

2014-Apr-15 18:43 UTC

[LLVMdev] [PATCH] Seh exceptions on Win64

Hi,

I'd like to submit a patch to match the clang patch on the front end.
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140414/103257.html

The front end doesn't need this patch to work but it's still important.
This is mostly based on work done by kai from redstar.de

Could I get some feedback on this?
I'm not sure if the emitting of the register names will effect msvc.

Many Thanks

Martell Malone
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Yaron Keren

2014-Apr-15 20:42 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

Hi,

 if (is64Bit && T.getOS() == Triple::MinGW32 &&
T.getEnvironment() &&
Triple::GNU)

should be

 if (is64Bit && Triple.isWindowsGNUEnvironment())

Yaron






2014-04-15 21:43 GMT+03:00 Martell Malone <martellmalone at gmail.com>:
> Hi,
>
> I'd like to submit a patch to match the clang patch on the front end.
>
>
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140414/103257.html
>
> The front end doesn't need this patch to work but it's still
important.
> This is mostly based on work done by kai from redstar.de
>
> Could I get some feedback on this?
> I'm not sure if the emitting of the register names will effect msvc.
>
> Many Thanks
>
> Martell Malone
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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Martell Malone

2014-Apr-15 20:45 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

Updated patch.

I've reordered seh patch to have includes in the correct location
Was a very sloppy edit before



On Tue, Apr 15, 2014 at 7:43 PM, Martell Malone <martellmalone at
gmail.com>wrote:
> Hi,
>
> I'd like to submit a patch to match the clang patch on the front end.
>
>
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140414/103257.html
>
> The front end doesn't need this patch to work but it's still
important.
> This is mostly based on work done by kai from redstar.de
>
> Could I get some feedback on this?
> I'm not sure if the emitting of the register names will effect msvc.
>
> Many Thanks
>
> Martell Malone
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Martell Malone

2014-Apr-15 20:50 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

Hi yaron,

Good spot :)
missed that in my conversion.

Updated patch attached


On Tue, Apr 15, 2014 at 9:45 PM, Martell Malone <martellmalone at
gmail.com>wrote:
> Updated patch.
>
> I've reordered seh patch to have includes in the correct location
> Was a very sloppy edit before
>
>
>
> On Tue, Apr 15, 2014 at 7:43 PM, Martell Malone <martellmalone at
gmail.com>wrote:
>
>> Hi,
>>
>> I'd like to submit a patch to match the clang patch on the front
end.
>>
>>
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140414/103257.html
>>
>> The front end doesn't need this patch to work but it's still
important.
>> This is mostly based on work done by kai from redstar.de
>>
>> Could I get some feedback on this?
>> I'm not sure if the emitting of the register names will effect
msvc.
>>
>> Many Thanks
>>
>> Martell Malone
>>
>
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Vadim Chugunov

2014-Apr-15 21:44 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

Hi,
I am curious - how does clang deal with epilogue-less functions that result
from _Raise_Exception being marked 'noreturn'?
I've also been playing with Kai's patch, and discovered that this tends
to
greatly confuse Windows stack unwinder in cases when noreturn call is at
the end of a function, so execution appears to flow directly into the
prologue of the next function.
It looks like MSVC solves this problem by inserting 'int 3' after calls
to
noreturns.  This is actually the prime motivation for me wanting to emit
code for
'unreachable'<http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-April/072145.html>...

Vadim

On Tue, Apr 15, 2014 at 11:43 AM, Martell Malone <martellmalone at
gmail.com>wrote:
> Hi,
>
> I'd like to submit a patch to match the clang patch on the front end.
>
>
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140414/103257.html
>
> The front end doesn't need this patch to work but it's still
important.
> This is mostly based on work done by kai from redstar.de
>
> Could I get some feedback on this?
> I'm not sure if the emitting of the register names will effect msvc.
>
> Many Thanks
>
> Martell Malone
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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Vadim Chugunov

2014-Apr-15 21:44 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

Hi,
I am curious - how does clang deal with epilogue-less functions that result
from _Raise_Exception being marked 'noreturn'?
I've also been playing with Kai's patch, and discovered that this tends
to
greatly confuse Windows stack unwinder in cases when noreturn call is at
the end of a function, so execution appears to flow directly into the
prologue of the next function.
It looks like MSVC solves this problem by inserting 'int 3' after calls
to
noreturns.  This is actually the prime motivation for me wanting to emit
code for
'unreachable'<http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-April/072145.html>...

Vadim

On Tue, Apr 15, 2014 at 11:43 AM, Martell Malone <martellmalone at
gmail.com>wrote:
> Hi,
>
> I'd like to submit a patch to match the clang patch on the front end.
>
>
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140414/103257.html
>
> The front end doesn't need this patch to work but it's still
important.
> This is mostly based on work done by kai from redstar.de
>
> Could I get some feedback on this?
> I'm not sure if the emitting of the register names will effect msvc.
>
> Many Thanks
>
> Martell Malone
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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Nico Rieck

2014-Apr-16 03:53 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

On 15.04.2014 20:43, Martell Malone wrote:> Could I get some feedback on this?
> I'm not sure if the emitting of the register names will effect msvc.
Emitting the register names LGTM (in fact GAS doesn't seem to be able to
parse this anyway). Since this is just GAS assembly, this does not
affect MSVC. Some tests would be nice, if possible.

Unwind emission still suffers from the same problems that the old code
did. It doesn't handle realigned stacks, and as I summarized in PR16779,
I believe it's not necessary to change the prologue emission for Win64.
Currently ilist_node::getPrevNode of MachineInstr is unusable because it
segfaults on the first node in a list. I raised this issue before on
llvm-dev and proposed a patch but nobody cared, so you have to do
something like this:

  static const MachineInstr *getPrevNode(const MachineInstr *MI) {
    if (&*MI->getParent()->instr_begin() == MI)
      return nullptr;
    return MI->getPrevNode();
  }

Some small nits:
> +      if (MI->getOperand(1).getImm() != 1 ||
MI->getOperand(2).getImm() != 0 ||
> +          MI->getOperand(4).getImm()  != 0)
Spacing. Also, a comment clarifying that scale/index/segment must be
unused might be helpful here.

+  if (MI->getNextNode()) {
+    const MachineInstr *MI2 = MI->getNextNode();
+    if (!(MI2->getFlag(MachineInstr::FrameSetup) ||
+          (MI2->isCFIInstruction() && MI2->getNextNode()
&&
+           MI2->getNextNode()->getFlag(MachineInstr::FrameSetup)))) {
+      OutStreamer.EmitWin64EHEndProlog();
+    }
+  }

I'd simplify this and just skip over all CFI instructions. If there's
still a node left, and it lacks the FrameSetup flag, end the prolog.
> +; WIN64: callq {{__chkstk|___chkstk_ms}}
This check should really differentiate between MSVC and Mingw. You can
add additional FileCheck prefixes so the rest does not have to be
duplicated.

Overall this needs more tests covering __chkstk, alloca, manual
over-alignment and various combinations.


On 15.04.2014 23:44, Vadim Chugunov wrote:> I am curious - how does clang deal with epilogue-less functions that result
> from _Raise_Exception being marked 'noreturn'?
AFAIK it doesn't emit anything.
> I've also been playing with Kai's patch, and discovered that this
tends to
> greatly confuse Windows stack unwinder in cases when noreturn call is at
> the end of a function, so execution appears to flow directly into the
> prologue of the next function.
> It looks like MSVC solves this problem by inserting 'int 3' after
calls to
> noreturns.
The unwinder starts scanning forward looking for an optional add or lea,
then zero or more register pops, followed by a ret or a few simple jmp
variants. So you can insert anything except these. Though int3 would
probably make the most sense.

-Nico

Kai Nacke

2014-Apr-17 17:10 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

Hi,

On 15.04.2014 23:44, Vadim Chugunov wrote:> Hi,
> I am curious - how does clang deal with epilogue-less functions that
> result from _Raise_Exception being marked 'noreturn'?
> I've also been playing with Kai's patch, and discovered that this
tends
> to greatly confuse Windows stack unwinder in cases when noreturn call is
> at the end of a function, so execution appears to flow directly into the
> prologue of the next function.
Yes, that's true. The patch has a problem if the epilogue is dead code 
and eliminated.
> It looks like MSVC solves this problem by inserting 'int 3' after
calls
> to noreturns.  This is actually the prime motivation for me wanting to
> emit code for 'unreachable'
> <http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-April/072145.html>
...
>
> Vadim
Yaron also pointed out that

int main() { throw 1; }

generates two .seh_endprologue instructions. I still did not fix this bug.

Regards,
Kai

>
>
> On Tue, Apr 15, 2014 at 11:43 AM, Martell Malone
> <martellmalone at gmail.com <mailto:martellmalone at
gmail.com>> wrote:
>
>     Hi,
>
>     I'd like to submit a patch to match the clang patch on the front
end.
>    
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140414/103257.html
>
>     The front end doesn't need this patch to work but it's still
important.
>     This is mostly based on work done by kai from redstar.de
>     <http://redstar.de>
>
>     Could I get some feedback on this?
>     I'm not sure if the emitting of the register names will effect
msvc.
>
>     Many Thanks
>
>     Martell Malone
>
>     _______________________________________________
>     LLVM Developers mailing list
>     LLVMdev at cs.uiuc.edu <mailto:LLVMdev at cs.uiuc.edu>
http://llvm.cs.uiuc.edu
>     http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Chandler Carruth

2014-Apr-18 09:31 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

On Tue, Apr 15, 2014 at 11:43 AM, Martell Malone <martellmalone at
gmail.com>wrote:
> This is mostly based on work done by kai from redstar.de
>
Martell, you really cannot post patches for review or otherwise contribute
them to LLVM unless you authored the patch. If Kai authored the patch, then
Kai needs to contirbute it.
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Yaron Keren

2014-Apr-18 09:47 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

Hi Chandler,

Kai contributed the WIN64 SEH patch some time ago on llvm-commits:


http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20131118/196105.html

it was never completed. Kai also responded in this thread.

I opened a phabricator for the patch

  http://reviews.llvm.org/D3418

Yaron



2014-04-18 12:31 GMT+03:00 Chandler Carruth <chandlerc at google.com>:
>
> On Tue, Apr 15, 2014 at 11:43 AM, Martell Malone <martellmalone at
gmail.com>wrote:
>
>> This is mostly based on work done by kai from redstar.de
>>
>
> Martell, you really cannot post patches for review or otherwise contribute
> them to LLVM unless you authored the patch. If Kai authored the patch, then
> Kai needs to contirbute it.
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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Kai Nacke

2014-Apr-22 07:10 UTC

head link

[LLVMdev] [PATCH] Seh exceptions on Win64

Hi Chandler & all others,

yes, I contribute the patch here. :-)

Regards,
Kai

On 18.04.2014 11:31, Chandler Carruth wrote:>
> On Tue, Apr 15, 2014 at 11:43 AM, Martell Malone
> <martellmalone at gmail.com <mailto:martellmalone at
gmail.com>> wrote:
>
>     This is mostly based on work done by kai from redstar.de
>     <http://redstar.de>
>
>
> Martell, you really cannot post patches for review or otherwise
> contribute them to LLVM unless you authored the patch. If Kai authored
> the patch, then Kai needs to contirbute it.
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

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