[CodeGen] Enable Windows exception handling for basic block sections

[TaoPan]

Summary

Windows x64 exception handling is quite different with Exception
Handling of Itanium C++ ABI for IA-64, no need to do EH pad operation.

Reference:
https://docs.microsoft.com/en-us/cpp/build/exception-handling-x64?view=msvc-160
https://github.com/itanium-cxx-abi/cxx-abi/blob/master/exceptions.pdf

[TaoPan]

git rebase

[TaoPan]

Remove content of parent D99487 for applying this patch

[TaoPan]

Remove content of parent D99487 for applying this patch

[TaoPan]

git rebase

[modimo]

Is there currently a difference in the output when built with -basic-block-sections=all -unique-basic-block-section-names vs. without? If so, should CHECK for both cases to highlight the difference and add some explanatory comments on why a particular transformation took place. What are considered landing pads for avoidZeroOffsetLandingPad under MSVC? I can double-check to make sure they're truly not needed.

Otherwise this looks good and works well as a first step.

[TaoPan]

In D100735#2832069, @modimo wrote:

Is there currently a difference in the output when built with -basic-block-sections=all -unique-basic-block-section-names vs. without? If so, should CHECK for both cases to highlight the difference and add some explanatory comments on why a particular transformation took place. What are considered landing pads for avoidZeroOffsetLandingPad under MSVC? I can double-check to make sure they're truly not needed.

Otherwise this looks good and works well as a first step.

Thanks for your comment!
No big difference. There are 12 more sections in Sections table, I checked asm file, there are 12 BB sections, so all added sections are BB sections. And as the test file CHECK, one relocation of .xdata section changed from ".text" to "?TestCPPEX@@YAXH@Z.__part.3". Is this difference need to add without -basic-block-sections=all -unique-basic-block-section-names case for highlight the difference?
FYI, about avoidZeroOffsetLandingPad under MSVC, isFuncletEHPersonality(Pers) check and return of SelectionDAGISel::PrepareEHLandingPad() prevent later addLandingPad(MBB) and adding TargetOpcode::EH_LABEL MachineInstr in the case of MSVC. while (!MI->isEHLabel()) ++MI; of avoidZeroOffsetLandingPad is dead loop as no EHLabel MI in the case of MSVC.

[modimo]

In D100735#2832513, @TaoPan wrote:

No big difference. There are 12 more sections in Sections table, I checked asm file, there are 12 BB sections, so all added sections are BB sections. And as the test file CHECK, one relocation of .xdata section changed from ".text" to "?TestCPPEX@@YAXH@Z.__part.3". Is this difference need to add without -basic-block-sections=all -unique-basic-block-section-names case for highlight the difference?

Yeah, check that the .xdata relocation changed and the size of the Sections table (CHECK-COUNT or looking at the last entry for each configuration). Also does the above test case run correctly when built with Clang if you define it as "main" and add something interesting to the __except clause (with and without BBS)?

FYI, about avoidZeroOffsetLandingPad under MSVC, isFuncletEHPersonality(Pers) check and return of SelectionDAGISel::PrepareEHLandingPad() prevent later addLandingPad(MBB) and adding TargetOpcode::EH_LABEL MachineInstr in the case of MSVC. while (!MI->isEHLabel()) ++MI; of avoidZeroOffsetLandingPad is dead loop as no EHLabel MI in the case of MSVC.

I'm not sure what you mean by dead loop for while (!MI->isEHLabel()) Can you elaborate?

[TaoPan]

Add baseline case and check size of the Sections table

[TaoPan]

In D100735#2834985, @modimo wrote:

In D100735#2832513, @TaoPan wrote:

No big difference. There are 12 more sections in Sections table, I checked asm file, there are 12 BB sections, so all added sections are BB sections. And as the test file CHECK, one relocation of .xdata section changed from ".text" to "?TestCPPEX@@YAXH@Z.__part.3". Is this difference need to add without -basic-block-sections=all -unique-basic-block-section-names case for highlight the difference?

Yeah, check that the .xdata relocation changed and the size of the Sections table (CHECK-COUNT or looking at the last entry for each configuration). Also does the above test case run correctly when built with Clang if you define it as "main" and add something interesting to the __except clause (with and without BBS)?

I added baseline (without BBS) case and check the size of the Sections table.
I tried to build with clang, define it as "main" and add printf to the __except clause

without BBS, the exception can be captured, printf log in __except clause was printed.
with BBS,  build fail with "error: Cannot represent this expression", I'm investigating this error.

FYI, about avoidZeroOffsetLandingPad under MSVC, isFuncletEHPersonality(Pers) check and return of SelectionDAGISel::PrepareEHLandingPad() prevent later addLandingPad(MBB) and adding TargetOpcode::EH_LABEL MachineInstr in the case of MSVC. while (!MI->isEHLabel()) ++MI; of avoidZeroOffsetLandingPad is dead loop as no EHLabel MI in the case of MSVC.

I'm not sure what you mean by dead loop for while (!MI->isEHLabel()) Can you elaborate?

The dead loop occurs if "MBB->setIsEHPad() but all MIs of the MBB are not isEHLabel()", as condition !MI->isEHLabel() of while loop is always true.
Adding "&& MI != MBB.end()" to while (!MI->isEHLabel()) will resolve this dead loop.
The iterator is rolling loop, begin() is next to end(), the '++' operation change the iterator in loop turn, e.g. if size() is 2, the turn of '++' operation is:

begin() (1st node) -> 2nd node -> end() -> begin() (1st node) -> 2nd node -> ....

I don't know the reason MBB->setIsEHPad() without any MI of the MBB setIsEHLabel() in the case of Windows COFF.

[modimo]

In D100735#2838154, @TaoPan wrote:

I added baseline (without BBS) case and check the size of the Sections table.

Nice thanks. One comment on the format.

I tried to build with clang, define it as "main" and add printf to the __except clause

without BBS, the exception can be captured, printf log in __except clause was printed.
with BBS,  build fail with "error: Cannot represent this expression", I'm investigating this error.

Cool, feel free to file a bug and link it here to track progress.

The iterator is rolling loop, begin() is next to end(), the '++' operation change the iterator in loop turn, e.g. if size() is 2, the turn of '++' operation is:

begin() (1st node) -> 2nd node -> end() -> begin() (1st node) -> 2nd node -> ....

Ah it becomes infinite, thanks for clarifying.

I don't know the reason MBB->setIsEHPad() without any MI of the MBB setIsEHLabel() in the case of Windows COFF.

My cursory understanding is that Windows COFF in LLVM uses a different set of intrinsics to represent EH which probably don't fall under EHLabel. There's probably a good reason for that. If this is the case then probably better to guard it like you're currently doing from scanning wastefully. I would guard with if (!<triple for windows>) rather specifically checking for ELF. Also, put the check inside avoidZeroOffsetLandingPad rather than the call to it so the call site doesn't have to be aware of this.

llvm/test/MC/COFF/seh-bbs.ll

89

I would interleave these with the baseline so its easy to see how exactly the codegen differs, for this example:

FileCheck --check-prefix=COMMON,BASELINE %s
FileCheck --check-prefix=COMMON,BBS %s
...
; COMMON:          Relocations [
; COMMON-NEXT:       0xC IMAGE_REL_AMD64_ADDR32NB __C_specific_handler
; COMMON-NEXT:       0x14 IMAGE_REL_AMD64_ADDR32NB .text
; COMMON-NEXT:       0x18 IMAGE_REL_AMD64_ADDR32NB .text
; BASELINE:       0x20 IMAGE_REL_AMD64_ADDR32NB .text
; BBS:            0x20 IMAGE_REL_AMD64_ADDR32NB ?TestCPPEX@@YAXH@Z.__part.3

It's also good to add short comments for these diff spots on why this is expected behavior.

[TaoPan]

Change CHECK format of test to COMMON, BASELINE, BBS for highlighting difference of BASELINE and BBS.
Change triple condition from COFF to Windows.
Move check of Windows inside avoidZeroOffsetLandingPad.
Add iterator end check for avoiding infinite loop.

[TaoPan]

Add comment for difference of section number of BASELINE and BBS

[TaoPan]

In D100735#2842162, @modimo wrote:

In D100735#2838154, @TaoPan wrote:

I tried to build with clang, define it as "main" and add printf to the __except clause

without BBS, the exception can be captured, printf log in __except clause was printed.
with BBS,  build fail with "error: Cannot represent this expression", I'm investigating this error.

Cool, feel free to file a bug and link it here to track progress.

This bug depends on #D99487 and this commit, can't be reproduced without these two commits. Is it ok file the bug after landing these two commits?

I don't know the reason MBB->setIsEHPad() without any MI of the MBB setIsEHLabel() in the case of Windows COFF.

My cursory understanding is that Windows COFF in LLVM uses a different set of intrinsics to represent EH which probably don't fall under EHLabel. There's probably a good reason for that. If this is the case then probably better to guard it like you're currently doing from scanning wastefully. I would guard with if (!<triple for windows>) rather specifically checking for ELF. Also, put the check inside avoidZeroOffsetLandingPad rather than the call to it so the call site doesn't have to be aware of this.

Thanks for your analysis! I changed code according to your guidance.

llvm/test/MC/COFF/seh-bbs.ll

89

Good idea! I changed check format as you guided.

[modimo]

In D100735#2843362, @TaoPan wrote:

In D100735#2842162, @modimo wrote:

Cool, feel free to file a bug and link it here to track progress.

This bug depends on #D99487 and this commit, can't be reproduced without these two commits. Is it ok file the bug after landing these two commits?

In that case it would make sense to fix this in D99487. I pulled this down locally and noticed that baseline testing with BBS hits:

llc: /home/modimo/llvm-project/llvm/lib/MC/MCStreamer.cpp:1207: virtual void llvm::MCStreamer::SwitchSection(llvm::MCSection *, const llvm::MCExpr *): Assertion Section && "Cannot switch to a null section!"' failed.`

If you plan on checking this test in early (which I would recommend) before all the other pieces are in place you can replace RUN for BBS with a TODO D99487.

llvm/test/MC/COFF/seh-bbs.ll

51

";" for comment lines

[TaoPan]

Fix comment format of test

[TaoPan]

In D100735#2845073, @modimo wrote:

In D100735#2843362, @TaoPan wrote:

In D100735#2842162, @modimo wrote:

Cool, feel free to file a bug and link it here to track progress.

This bug depends on #D99487 and this commit, can't be reproduced without these two commits. Is it ok file the bug after landing these two commits?

In that case it would make sense to fix this in D99487. I pulled this down locally and noticed that baseline testing with BBS hits:

llc: /home/modimo/llvm-project/llvm/lib/MC/MCStreamer.cpp:1207: virtual void llvm::MCStreamer::SwitchSection(llvm::MCSection *, const llvm::MCExpr *): Assertion Section && "Cannot switch to a null section!"' failed.`

If you plan on checking this test in early (which I would recommend) before all the other pieces are in place you can replace RUN for BBS with a TODO D99487.

I set D99487 as this patch's parent according to @tmsriram 's comment, it's the reason why the auto test passed but you pull only this down locally and run this test crash. The section of SwitchSection() is created by D99487.
I submitted BBS patches according to purpose:

D99487 (parent of the below two patches): BBS basic function on Windows
D100735 (this patch):  BBS exception handling on Windows
D101421: BBS DebugInfo on Windows

So the upper mentioned bug "with BBS, build fail with "error: Cannot represent this expression", I'm investigating this error" belongs to this patch.

llvm/test/MC/COFF/seh-bbs.ll

51

Thanks! I changed to ";"

[TaoPan]

Update test for reproducing build error of "<unknown>:0: error: Cannot represent this expression" and fix the error

[modimo]

In D100735#2846280, @TaoPan wrote:

D99487 (parent of the below two patches): BBS basic function on Windows
D100735 (this patch):  BBS exception handling on Windows
D101421: BBS DebugInfo on Windows

Is the plan to commit all of this at once?

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

3202 ↗

(On Diff #356080)

How does this change interact with the ELF beginFunclet/endFunclet?

[TaoPan]

In D100735#2860997, @modimo wrote:

In D100735#2846280, @TaoPan wrote:

D99487 (parent of the below two patches): BBS basic function on Windows
D100735 (this patch):  BBS exception handling on Windows
D101421: BBS DebugInfo on Windows

Is the plan to commit all of this at once?

Yes.
Could you please review this commit further?

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

3202 ↗

(On Diff #356080)

No impact.
The ELF child classes of class EHStream don't override beginFunclet/endFunclet, refer to llvm/lib/CodeGen/AsmPrinter/DwarfException.h, class DwarfCFIExceptionBase, DwarfCFIException, ARMException.
Only class WinException override beginFunclet/endFunclet of class EHStream, refer to llvm/lib/CodeGen/AsmPrinter/WinException.h, class WinException.

[TaoPan]

git rebase

[modimo]

LGTM

[TaoPan]

Thanks @modimo for big help!
Any other review comment?

[modimo]

In D100735#2872811, @TaoPan wrote:

Thanks @modimo for big help!
Any other review comment?

Not on this change no.

llvm/lib/CodeGen/BasicBlockSections.cpp

auto Comparator = [&](const MachineBasicBlock &X,
     // their position within the section.
     if (XSectionID.Type == MBBSectionID::SectionType::Default)
       return FuncBBClusterInfo[X.getNumber()]->PositionInCluster <
              FuncBBClusterInfo[Y.getNumber()]->PositionInCluster;
     return X.getNumber() < Y.getNumber();
   };
 
   sortBasicBlocksAndUpdateBranches(MF, Comparator);
+  if (MF.getTarget().getTargetTriple().isOSBinFormatELF())
     avoidZeroOffsetLandingPad(MF);
   return true;
 }
 
 // Basic Block Sections can be enabled for a subset of machine basic blocks.
 // This is done by passing a file containing names of functions for which basic
 // block sections are desired.  Additionally, machine basic block ids of the
 // functions can also be specified for a finer granularity. Moreover, a cluster
 // of basic blocks could be assigned to the same section.

llvm/test/MC/COFF/seh-bbs.ll

+; RUN: llc -simplifycfg-require-and-preserve-domtree=1 < %s -mtriple=x86_64-windows-msvc  -function-sections -basic-block-sections=all -unique-basic-block-section-names | llvm-mc -triple=x86_64-windows-msvc -filetype=obj - | llvm-readobj -S --sd --sr -u - | FileCheck %s
+
+; CHECK:      Sections [
+; CHECK:        Section {
+; CHECK:          Name: .xdata
+; CHECK:          RawDataSize: 36
+; CHECK:          RelocationCount: 4
+; CHECK:          Characteristics [
+; CHECK-NEXT:       IMAGE_SCN_ALIGN_4BYTES
+; CHECK-NEXT:       IMAGE_SCN_CNT_INITIALIZED_DATA
+; CHECK-NEXT:       IMAGE_SCN_LNK_COMDAT
+; CHECK-NEXT:       IMAGE_SCN_MEM_READ
+; CHECK-NEXT:     ]
+; CHECK:          Relocations [
+; CHECK-NEXT:       0xC IMAGE_REL_AMD64_ADDR32NB __C_specific_handler
+; CHECK-NEXT:       0x14 IMAGE_REL_AMD64_ADDR32NB .text
+; CHECK-NEXT:       0x18 IMAGE_REL_AMD64_ADDR32NB .text
+; CHECK-NEXT:       0x20 IMAGE_REL_AMD64_ADDR32NB ?TestCPPEX@@YAXH@Z.__part.3
+; CHECK-NEXT:     ]
+; CHECK:          SectionData (
+; CHECK-NEXT:       0000: 190A0345 0A030572 01500000 00000000
+; CHECK-NEXT:       0010: 01000000 01000000 11000000 01000000
+; CHECK-NEXT:       0020: 00000000
+; CHECK-NEXT:     )
+; CHECK-NEXT:   }
+; CHECK:        Section {
+; CHECK:          Name: .pdata
+; CHECK:          RawDataSize: 12
+; CHECK:          RelocationCount: 3
+; CHECK:          Characteristics [ (0x40301040)
+; CHECK-NEXT:       IMAGE_SCN_ALIGN_4BYTES (0x300000)
+; CHECK-NEXT:       IMAGE_SCN_CNT_INITIALIZED_DATA (0x40)
+; CHECK-NEXT:       IMAGE_SCN_LNK_COMDAT (0x1000)
+; CHECK-NEXT:       IMAGE_SCN_MEM_READ (0x40000000)
+; CHECK-NEXT:     ]
+; CHECK:          Relocations [
+; CHECK-NEXT:       0x0 IMAGE_REL_AMD64_ADDR32NB ?TestCPPEX@@YAXH@Z
+; CHECK-NEXT:       0x4 IMAGE_REL_AMD64_ADDR32NB ?TestCPPEX@@YAXH@Z
+; CHECK-NEXT:       0x8 IMAGE_REL_AMD64_ADDR32NB .xdata
+; CHECK-NEXT:     ]
+; CHECK:          SectionData (
+; CHECK-NEXT:       0000: 00000000 1C000000 00000000
+; CHECK-NEXT:     )
+; CHECK-NEXT:   }
+; CHECK:      ]
+; CHECK:      UnwindInformation [
+; CHECK:        RuntimeFunction {
+; CHECK-NEXT:     StartAddress: ?TestCPPEX@@YAXH@Z (0x0)
+; CHECK-NEXT:     EndAddress: ?TestCPPEX@@YAXH@Z +0x1C (0x4)
+; CHECK-NEXT:     UnwindInfoAddress: .xdata (0x8)
+; CHECK-NEXT:     UnwindInfo {
+; CHECK-NEXT:       Version: 1
+; CHECK-NEXT:       Flags [ (0x3)
+; CHECK-NEXT:         ExceptionHandler (0x1)
+; CHECK-NEXT:         TerminateHandler (0x2)
+; CHECK-NEXT:       ]
+; CHECK-NEXT:       PrologSize: 10
+; CHECK-NEXT:       FrameRegister: RBP (0x5)
+; CHECK-NEXT:       FrameOffset: 0x4
+; CHECK-NEXT:       UnwindCodeCount: 3
+; CHECK-NEXT:       UnwindCodes [
+; CHECK-NEXT:         0x0A: SET_FPREG reg=RBP, offset=0x40
+; CHECK-NEXT:         0x05: ALLOC_SMALL size=64
+; CHECK-NEXT:         0x01: PUSH_NONVOL reg=RBP
+; CHECK-NEXT:       ]
+; CHECK-NEXT:       Handler: __C_specific_handler (0xC)
+; CHECK-NEXT:     }
+; CHECK-NEXT:   }
+; CHECK:      ]
+
+; Generated with this C++ source:
+; #include <stdio.h>
+; #include <Windows.h>
+; #include <exception>
+; __declspec(noinline) void TestCPPEX(int index)
+; {
+;    __try
+;    {
+;      if (index > 10) {
+;        throw std::exception("");
+;      }
+;    }
+;    __except (EXCEPTION_EXECUTE_HANDLER)
+;    {
+;    }
+; }
+
+; ModuleID = 'wineh.cpp'
+source_filename = "wineh.cpp"
+target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc19.0.24245"
+
+%rtti.TypeDescriptor19 = type { i8**, i8*, [20 x i8] }
+%eh.CatchableType = type { i32, i32, i32, i32, i32, i32, i32 }
+%eh.CatchableTypeArray.1 = type { i32, [1 x i32] }
+%eh.ThrowInfo = type { i32, i32, i32, i32 }
+%rtti.CompleteObjectLocator = type { i32, i32, i32, i32, i32, i32 }
+%rtti.ClassHierarchyDescriptor = type { i32, i32, i32, i32 }
+%rtti.BaseClassDescriptor = type { i32, i32, i32, i32, i32, i32, i32 }
+%"class.std::exception" = type { i32 (...)**, %struct.__std_exception_data }
+%struct.__std_exception_data = type { i8*, i8 }
+
+$"??0exception@std@@QEAA@QEBD@Z" = comdat any
+
+$"??0exception@std@@QEAA@AEBV01@@Z" = comdat any
+
+$"??1exception@std@@UEAA@XZ" = comdat any
+
+$"??_Gexception@std@@UEAAPEAXI@Z" = comdat any
+
+$"?what@exception@std@@UEBAPEBDXZ" = comdat any
+
+$"??_C@_00CNPNBAHC@?$AA@" = comdat any
+
+$"??_R0?AVexception@std@@@8" = comdat any
+
+$"_CT??_R0?AVexception@std@@@824" = comdat any
+
+$"_CTA1?AVexception@std@@" = comdat any
+
+$"_TI1?AVexception@std@@" = comdat any
+
+$"??_7exception@std@@6B@" = comdat largest
+
+$"??_R4exception@std@@6B@" = comdat any
+
+$"??_R3exception@std@@8" = comdat any
+
+$"??_R2exception@std@@8" = comdat any
+
+$"??_R1A@?0A@EA@exception@std@@8" = comdat any
+
+$"??_C@_0BC@EOODALEL@Unknown?5exception?$AA@" = comdat any
+
+@"??_C@_00CNPNBAHC@?$AA@" = linkonce_odr dso_local unnamed_addr constant [1 x i8] zeroinitializer, comdat, align 1
+@"??_7type_info@@6B@" = external constant i8*
+@"??_R0?AVexception@std@@@8" = linkonce_odr global %rtti.TypeDescriptor19 { i8** @"??_7type_info@@6B@", i8* null, [20 x i8] c".?AVexception@std@@\00" }, comdat
+@__ImageBase = external dso_local constant i8
+@"_CT??_R0?AVexception@std@@@824" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 0, i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%rtti.TypeDescriptor19* @"??_R0?AVexception@std@@@8" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32), i32 0, i32 -1, i32 0, i32 24, i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%"class.std::exception"* (%"class.std::exception"*, %"class.std::exception"*)* @"??0exception@std@@QEAA@AEBV01@@Z" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32) }, section ".xdata", comdat
+@"_CTA1?AVexception@std@@" = linkonce_odr unnamed_addr constant %eh.CatchableTypeArray.1 { i32 1, [1 x i32] [i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%eh.CatchableType* @"_CT??_R0?AVexception@std@@@824" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32)] }, section ".xdata", comdat
+@"_TI1?AVexception@std@@" = linkonce_odr unnamed_addr constant %eh.ThrowInfo { i32 0, i32 trunc (i64 sub nuw nsw (i64 ptrtoint (void (%"class.std::exception"*)* @"??1exception@std@@UEAA@XZ" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32), i32 0, i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%eh.CatchableTypeArray.1* @"_CTA1?AVexception@std@@" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32) }, section ".xdata", comdat
+@0 = private unnamed_addr constant { [3 x i8*] } { [3 x i8*] [i8* bitcast (%rtti.CompleteObjectLocator* @"??_R4exception@std@@6B@" to i8*), i8* bitcast (i8* (%"class.std::exception"*, i32)* @"??_Gexception@std@@UEAAPEAXI@Z" to i8*), i8* bitcast (i8* (%"class.std::exception"*)* @"?what@exception@std@@UEBAPEBDXZ" to i8*)] }, comdat($"??_7exception@std@@6B@")
+@"??_R4exception@std@@6B@" = linkonce_odr constant %rtti.CompleteObjectLocator { i32 1, i32 0, i32 0, i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%rtti.TypeDescriptor19* @"??_R0?AVexception@std@@@8" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32), i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%rtti.ClassHierarchyDescriptor* @"??_R3exception@std@@8" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32), i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%rtti.CompleteObjectLocator* @"??_R4exception@std@@6B@" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32) }, comdat
+@"??_R3exception@std@@8" = linkonce_odr constant %rtti.ClassHierarchyDescriptor { i32 0, i32 0, i32 1, i32 trunc (i64 sub nuw nsw (i64 ptrtoint ([2 x i32]* @"??_R2exception@std@@8" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32) }, comdat
+@"??_R2exception@std@@8" = linkonce_odr constant [2 x i32] [i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%rtti.BaseClassDescriptor* @"??_R1A@?0A@EA@exception@std@@8" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32), i32 0], comdat
+@"??_R1A@?0A@EA@exception@std@@8" = linkonce_odr constant %rtti.BaseClassDescriptor { i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%rtti.TypeDescriptor19* @"??_R0?AVexception@std@@@8" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32), i32 0, i32 0, i32 -1, i32 0, i32 64, i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%rtti.ClassHierarchyDescriptor* @"??_R3exception@std@@8" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32) }, comdat
+@"??_C@_0BC@EOODALEL@Unknown?5exception?$AA@" = linkonce_odr dso_local unnamed_addr constant [18 x i8] c"Unknown exception\00", comdat, align 1
+
+@"??_7exception@std@@6B@" = unnamed_addr alias i8*, getelementptr inbounds ({ [3 x i8*] }, { [3 x i8*] }* @0, i32 0, i32 0, i32 1)
+
+; Function Attrs: noinline optnone uwtable mustprogress
+define dso_local void @"?TestCPPEX@@YAXH@Z"(i32 %0) #0 personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*) {
+  %2 = alloca i32, align 4
+  %3 = alloca i32, align 4
+  %4 = alloca %"class.std::exception", align 8
+  store i32 %0, i32* %2, align 4
+  %5 = load i32, i32* %2, align 4
+  %6 = icmp sgt i32 %5, 10
+  br i1 %6, label %7, label %18
+
+7:                                                ; preds = %1
+  %8 = invoke %"class.std::exception"* @"??0exception@std@@QEAA@QEBD@Z"(%"class.std::exception"* nonnull dereferenceable(24) %4, i8* getelementptr inbounds ([1 x i8], [1 x i8]* @"??_C@_00CNPNBAHC@?$AA@", i64 0, i64 0)) #7
+          to label %9 unwind label %11
+
+9:                                                ; preds = %7
+  %10 = bitcast %"class.std::exception"* %4 to i8*
+  invoke void @_CxxThrowException(i8* %10, %eh.ThrowInfo* @"_TI1?AVexception@std@@") #8
+          to label %19 unwind label %11
+
+11:                                               ; preds = %9, %7
+  %12 = catchswitch within none [label %13] unwind to caller
+
+13:                                               ; preds = %11
+  %14 = catchpad within %12 [i8* null]
+  catchret from %14 to label %15
+
+15:                                               ; preds = %13
+  %16 = call i32 @llvm.eh.exceptioncode(token %14)
+  store i32 %16, i32* %3, align 4
+  br label %17
+
+17:                                               ; preds = %15, %18
+  ret void
+
+18:                                               ; preds = %1
+  br label %17
+
+19:                                               ; preds = %9
+  unreachable
+}
+
+; Function Attrs: noinline nounwind optnone uwtable
+define linkonce_odr dso_local %"class.std::exception"* @"??0exception@std@@QEAA@QEBD@Z"(%"class.std::exception"* nonnull returned dereferenceable(24) %0, i8* %1) unnamed_addr #1 comdat align 2 {
+  %3 = alloca i8*, align 8
+  %4 = alloca %"class.std::exception"*, align 8
+  %5 = alloca %struct.__std_exception_data, align 8
+  store i8* %1, i8** %3, align 8
+  store %"class.std::exception"* %0, %"class.std::exception"** %4, align 8
+  %6 = load %"class.std::exception"*, %"class.std::exception"** %4, align 8
+  %7 = bitcast %"class.std::exception"* %6 to i32 (...)***
+  store i32 (...)** bitcast (i8** @"??_7exception@std@@6B@" to i32 (...)**), i32 (...)*** %7, align 8
+  %8 = getelementptr inbounds %"class.std::exception", %"class.std::exception"* %6, i32 0, i32 1
+  %9 = bitcast %struct.__std_exception_data* %8 to i8*
+  call void @llvm.memset.p0i8.i64(i8* align 8 %9, i8 0, i64 16, i1 false)
+  %10 = getelementptr inbounds %struct.__std_exception_data, %struct.__std_exception_data* %5, i32 0, i32 0
+  %11 = load i8*, i8** %3, align 8
+  store i8* %11, i8** %10, align 8
+  %12 = getelementptr inbounds %struct.__std_exception_data, %struct.__std_exception_data* %5, i32 0, i32 1
+  store i8 1, i8* %12, align 8
+  %13 = getelementptr inbounds %"class.std::exception", %"class.std::exception"* %6, i32 0, i32 1
+  call void @__std_exception_copy(%struct.__std_exception_data* %5, %struct.__std_exception_data* %13)
+  ret %"class.std::exception"* %6
+}
+
+declare dso_local i32 @__C_specific_handler(...)
+
+; Function Attrs: noinline nounwind optnone uwtable
+define linkonce_odr dso_local %"class.std::exception"* @"??0exception@std@@QEAA@AEBV01@@Z"(%"class.std::exception"* nonnull returned dereferenceable(24) %0, %"class.std::exception"* nonnull align 8 dereferenceable(24) %1) unnamed_addr #1 comdat align 2 {
+  %3 = alloca %"class.std::exception"*, align 8
+  %4 = alloca %"class.std::exception"*, align 8
+  store %"class.std::exception"* %1, %"class.std::exception"** %3, align 8
+  store %"class.std::exception"* %0, %"class.std::exception"** %4, align 8
+  %5 = load %"class.std::exception"*, %"class.std::exception"** %4, align 8
+  %6 = bitcast %"class.std::exception"* %5 to i32 (...)***
+  store i32 (...)** bitcast (i8** @"??_7exception@std@@6B@" to i32 (...)**), i32 (...)*** %6, align 8
+  %7 = getelementptr inbounds %"class.std::exception", %"class.std::exception"* %5, i32 0, i32 1
+  %8 = bitcast %struct.__std_exception_data* %7 to i8*
+  call void @llvm.memset.p0i8.i64(i8* align 8 %8, i8 0, i64 16, i1 false)
+  %9 = getelementptr inbounds %"class.std::exception", %"class.std::exception"* %5, i32 0, i32 1
+  %10 = load %"class.std::exception"*, %"class.std::exception"** %3, align 8
+  %11 = getelementptr inbounds %"class.std::exception", %"class.std::exception"* %10, i32 0, i32 1
+  call void @__std_exception_copy(%struct.__std_exception_data* %11, %struct.__std_exception_data* %9)
+  ret %"class.std::exception"* %5
+}
+
+; Function Attrs: noinline nounwind optnone uwtable
+define linkonce_odr dso_local void @"??1exception@std@@UEAA@XZ"(%"class.std::exception"* nonnull dereferenceable(24) %0) unnamed_addr #1 comdat align 2 {
+  %2 = alloca %"class.std::exception"*, align 8
+  store %"class.std::exception"* %0, %"class.std::exception"** %2, align 8
+  %3 = load %"class.std::exception"*, %"class.std::exception"** %2, align 8
+  %4 = bitcast %"class.std::exception"* %3 to i32 (...)***
+  store i32 (...)** bitcast (i8** @"??_7exception@std@@6B@" to i32 (...)**), i32 (...)*** %4, align 8
+  %5 = getelementptr inbounds %"class.std::exception", %"class.std::exception"* %3, i32 0, i32 1
+  call void @__std_exception_destroy(%struct.__std_exception_data* %5)
+  ret void
+}
+
+declare dso_local void @_CxxThrowException(i8*, %eh.ThrowInfo*)
+
+; Function Attrs: nounwind readnone
+declare i32 @llvm.eh.exceptioncode(token) #2
+
+; Function Attrs: argmemonly nofree nosync nounwind willreturn writeonly
+declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg) #3
+
+declare dso_local void @__std_exception_copy(%struct.__std_exception_data*, %struct.__std_exception_data*) #4
+
+; Function Attrs: noinline nounwind optnone uwtable
+define linkonce_odr dso_local i8* @"??_Gexception@std@@UEAAPEAXI@Z"(%"class.std::exception"* nonnull dereferenceable(24) %0, i32 %1) unnamed_addr #1 comdat align 2 {
+  %3 = alloca i8*, align 8
+  %4 = alloca i32, align 4
+  %5 = alloca %"class.std::exception"*, align 8
+  store i32 %1, i32* %4, align 4
+  store %"class.std::exception"* %0, %"class.std::exception"** %5, align 8
+  %6 = load %"class.std::exception"*, %"class.std::exception"** %5, align 8
+  %7 = bitcast %"class.std::exception"* %6 to i8*
+  store i8* %7, i8** %3, align 8
+  %8 = load i32, i32* %4, align 4
+  call void @"??1exception@std@@UEAA@XZ"(%"class.std::exception"* nonnull dereferenceable(24) %6) #9
+  %9 = icmp eq i32 %8, 0
+  br i1 %9, label %12, label %10
+
+10:                                               ; preds = %2
+  %11 = bitcast %"class.std::exception"* %6 to i8*
+  call void @"??3@YAXPEAX@Z"(i8* %11) #10
+  br label %12
+
+12:                                               ; preds = %10, %2
+  %13 = load i8*, i8** %3, align 8
+  ret i8* %13
+}
+
+; Function Attrs: noinline nounwind optnone uwtable mustprogress
+define linkonce_odr dso_local i8* @"?what@exception@std@@UEBAPEBDXZ"(%"class.std::exception"* nonnull dereferenceable(24) %0) unnamed_addr #5 comdat align 2 {
+  %2 = alloca %"class.std::exception"*, align 8
+  store %"class.std::exception"* %0, %"class.std::exception"** %2, align 8
+  %3 = load %"class.std::exception"*, %"class.std::exception"** %2, align 8
+  %4 = getelementptr inbounds %"class.std::exception", %"class.std::exception"* %3, i32 0, i32 1
+  %5 = getelementptr inbounds %struct.__std_exception_data, %struct.__std_exception_data* %4, i32 0, i32 0
+  %6 = load i8*, i8** %5, align 8
+  %7 = icmp ne i8* %6, null
+  br i1 %7, label %8, label %12
+
+8:                                                ; preds = %1
+  %9 = getelementptr inbounds %"class.std::exception", %"class.std::exception"* %3, i32 0, i32 1
+  %10 = getelementptr inbounds %struct.__std_exception_data, %struct.__std_exception_data* %9, i32 0, i32 0
+  %11 = load i8*, i8** %10, align 8
+  br label %13
+
+12:                                               ; preds = %1
+  br label %13
+
+13:                                               ; preds = %12, %8
+  %14 = phi i8* [ %11, %8 ], [ getelementptr inbounds ([18 x i8], [18 x i8]* @"??_C@_0BC@EOODALEL@Unknown?5exception?$AA@", i64 0, i64 0), %12 ]
+  ret i8* %14
+}
+
+; Function Attrs: nobuiltin nounwind
+declare dso_local void @"??3@YAXPEAX@Z"(i8*) #6
+
+declare dso_local void @__std_exception_destroy(%struct.__std_exception_data*) #4
+
+attributes #0 = { noinline optnone uwtable mustprogress "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { noinline nounwind optnone uwtable "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
+attributes #3 = { argmemonly nofree nosync nounwind willreturn writeonly }
+attributes #4 = { "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #5 = { noinline nounwind optnone uwtable mustprogress "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #6 = { nobuiltin nounwind "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #7 = { noinline nounwind }
+attributes #8 = { noreturn }
+attributes #9 = { nounwind }
+attributes #10 = { builtin nounwind }
+
+!llvm.linker.options = !{!0, !1, !1, !2, !3, !4, !5}
+!llvm.module.flags = !{!6, !7}
+!llvm.ident = !{!8}
+
+!0 = !{!"/FAILIFMISMATCH:\22_CRT_STDIO_ISO_WIDE_SPECIFIERS=0\22"}
+!1 = !{!"/DEFAULTLIB:uuid.lib"}
+!2 = !{!"/FAILIFMISMATCH:\22_MSC_VER=1900\22"}
+!3 = !{!"/FAILIFMISMATCH:\22_ITERATOR_DEBUG_LEVEL=0\22"}
+!4 = !{!"/FAILIFMISMATCH:\22RuntimeLibrary=MT_StaticRelease\22"}
+!5 = !{!"/DEFAULTLIB:libcpmt.lib"}
+!6 = !{i32 1, !"wchar_size", i32 2}
+!7 = !{i32 7, !"PIC Level", i32 2}
+!8 = !{!"clang version 12.0.0 (https://github.com/llvm/llvm-project.git 5207f19d103dc3e0ec974fa64d2c031d84d497a8)"}