[clang] Improve Serialization/Imporing of APValues

[Tyker]

Summary

Changes:

• initializer expressions of constexpr variable are now wraped in a ConstantExpr. this is mainly used for testing purposes. the old caching system has not yet been removed.
• Add all the missing Serialization and Importing for APValue.
• Cleanup leftover from last patch.
• Add Tests for Import and serialization.

[Tyker]

Change:

• Add support for LValue, MemberPointer and AddrDiffExpr.
• Add tests for importing.

i wasn't able to test for some APValueKinds: FixePoint, ComplexInt, ComplexFloat, AddrLabelDiff.
LValue could need more tests. i am not sure all edges cases are covered.

[martong]

clang/include/clang/AST/ASTImporter.h

510

typo: Constext -> Context
Also, we return with the APValue in the "to" context, not the one in the "from" context.

clang/lib/AST/ASTImporter.cpp

8936

Looks okay, but could we have unit tests for this in ASTImporterTest.cpp?

[Tyker]

fixed comment typo.

clang/lib/AST/ASTImporter.cpp

8936

I tested importing using the same test file as serialization clang/test/PCH/APValue.cpp with -ast-merge which uses importing. this prevent duplicating the test code for importing and serializing. is the unit-test in ASTImporterTest.cpp necessary anyway ?

[martong]

clang/include/clang/AST/ASTImporter.h

510

The typo is still there: Constext has an extra s.

clang/lib/AST/ASTImporter.cpp

8936

Okay, that's fine I missed that previously, so there is no need for the unit-tests in this case.
Though maybe the -ast-merge part of the test should reside in the clang/test/ASTMerge directory, because that is where all the other -ast-merge tests are.
I am not sure how to solve that nicely, because i see you use the same file for both the serialization and for the import.
Perhaps there should be a common header file which is included both in test/PCH/APValue.cpp and in test/ASTMerge/apvalue/test.cpp?

[Tyker]

fixed the comment for good, sorry for that.

[Tyker]

clang/lib/AST/ASTImporter.cpp

8936

we can have a common header, but i don't know where to put it. having a in PCH that includes a header form ASTMerge seems weird and vice versa.

[martong]

clang/lib/AST/ASTImporter.cpp

8936

Yes, that is indeed not so good.

The point is that, we should execute the APValue tests as well when we invoke ninja check-clang-astmerge. (Some people do not execute the whole check-clang verification when they change only the ASTImporter, this way the edit-test cycle can be faster)

Can we have a symbolic link from test/PCH/APValue.cpp to test/ASTMerge/APValue.cpp? Probably that would work on *nix, but not on Windows (https://stackoverflow.com/questions/5917249/git-symlinks-in-windows).
If the symlink is really not an option then I am just fine with a real copy of the file.
If we have a link or a copy then the tests will run twice, that seems ok for me, but may disturb other devs.
Actually, this is an inconvenient problem, perhaps someone had this before, so maybe a mail to cfe-dev could help us out.

[Tyker]

Sorry for the long wait.

Changes:

• Rebased on current master
• Duplicated test file so that it runs for both importing

[martong]

In D63640#1648700, @Tyker wrote:

Sorry for the long wait.

Changes:

• Rebased on current master
• Duplicated test file so that it runs for both importing

Thanks for addressing the issues. The ASTImporter related changes look good to me now.

[aaron.ballman]

clang/include/clang/AST/APValue.h

573

reserveVector per naming conventions

clang/include/clang/AST/ASTContext.h

293

Why are you getting rid of this? It seems like we would still want these cleaned up.

clang/include/clang/AST/Expr.h

957 ↗

(On Diff #217600)

Enumerator -> Enumerators
there -> their

clang/include/clang/AST/TextNodeDumper.h

149 ↗

(On Diff #217600)

Good catch -- this pointed out a bug in the class that I've fixed in r372323, so you'll need to rebase.

clang/lib/AST/APValue.cpp

211

Why is this no longer a pointer to const?

874

Can this function be marked const?

clang/lib/AST/ASTImporter.cpp

8936

Conflict markers?

9164

Please don't use auto as the type is not spelled out in the initialization.

9169

Please don't use auto as the type is not spelled out in the initialization.

(Same elsewhere, I'll stop commenting on them.)

clang/lib/AST/TextNodeDumper.cpp

691–695 ↗

(On Diff #217600)

You'll have to rebase this too -- these changes shouldn't be needed any longer.

clang/lib/Sema/SemaDecl.cpp

11315 ↗

(On Diff #217600)

Can elide braces.

clang/lib/Serialization/ASTReader.cpp

9024

auto *

9030–9031

auto *

9037

auto *

9048–9054

These names don't match the current coding conventions.

9057

You should add parens here to avoid diagnostics.

clang/lib/Serialization/ASTWriter.cpp

5205

Name doesn't match coding conventions.

5216

const auto *

5238

const auto *

5242

const auto *

5260

Unrelated change?

clang/lib/Serialization/ASTWriterStmt.cpp

42 ↗

(On Diff #217600)

It seems like there's a lot of unrelated formatting changes in this file that should not be part of the patch.

[Tyker]

Fixed most changes requested by @aaron.ballman
test are currently no valid anymore see comments for why.

clang/include/clang/AST/ASTContext.h

293

when i added APValueCleanups i wasn't aware that there were a generic system to handle this. but with this patch APValue a cleaned up using the generic ASTContext::addDestruction.

clang/include/clang/AST/TextNodeDumper.h

149 ↗

(On Diff #217600)

i took a look at the revision. there is a big difference is the quality of output between APValue::dump and APValue::printPretty. i think it is possible to come quite close to printPretty's output even without the ASTContext. this would require having a default PrintingPolicy and improving dump

in this patch i was relying on the -ast-dump output for testing. i would need to find an other testing strategy or make the improvement to APValue::dump first.

clang/lib/AST/APValue.cpp

211

when imporing or deserializing, we reserve the space for elements and then import/deserialize element directly in place. so the buffer storing them is not const. that said i saw that the normal construction cast away the const.

874

this function gives access to non-const internal data. this function is private so the impact is quite limited.

[Tyker]

clang/lib/AST/APValue.cpp

211

never mind this change wasn't needed.

[aaron.ballman]

clang/include/clang/AST/APValue.h

573

This was marked as done but is still an issue.

593–596

Rather than add this private bit in the middle of the public interface, you can move this to the existing private parts.

659

We're horribly inconsistent in this class, but because the other private member functions go with it, this should probably be GetMemberPointerPathPtr(). Maybe rename the get/setLValue methods from above as well?

clang/include/clang/AST/ASTContext.h

293

I don't see any new calls to addDestruction() though. Have I missed something?

clang/include/clang/AST/TextNodeDumper.h

149 ↗

(On Diff #217600)

there is a big difference is the quality of output between APValue::dump and APValue::printPretty.

Yes, there is.

i think it is possible to come quite close to printPretty's output even without the ASTContext. this would require having a default PrintingPolicy and improving dump

That would be much-appreciated! When I looked at it, it seemed like it may not be plausible because Stmt does not track which ASTContext it is associated with the same way that Decl does, and changing that seemed likely to cause a huge amount of interface churn.

in this patch i was relying on the -ast-dump output for testing. i would need to find an other testing strategy or make the improvement to APValue::dump first.

The issue resolved by r372323 was that we would crash on certain kinds of AST dumps. Specifically, the default AST dumper is often used during a debugging session to dump AST node information within the debugger. It was trivial to get that to crash before r372323, but with that revision, we no longer crash but get slightly uglier output (which is acceptable because it's still human-readable output).

I'm sorry for causing extra pain for you here, but I didn't want the fix from this review to accidentally become an enshrined part of the API because it's very easy to forget about this use case when working on AST dumping functionality.

clang/lib/AST/APValue.cpp

874

That makes it harder to call this helper from a constant context. I think there should be overloads (one const, one not) to handle this.

clang/test/ASTMerge/APValue/APValue.cpp

2

Can remove the spurious newline. Also, it seems this file was added with svn properties, was that intentional (we don't usually do that, FWIW)?

3–4

no need for -x c++ is there? This is already a C++ compilation unit.

29

Are you planning to address this in this patch? Also, I think it's FixedPoint and not FixePoint.

clang/test/PCH/APValue.cpp

1 ↗

(On Diff #221169)

Spurious newline.

2 ↗

(On Diff #221169)

-x c++ ?

It's really unfortunate that these test files are identical copies in different directories.

28 ↗

(On Diff #221169)

Same comment here.

[Tyker]

fixed some changes.
see comments for others.

clang/include/clang/AST/APValue.h

573

sorry

clang/test/PCH/APValue.cpp

2 ↗

(On Diff #221169)

they are almost the same. the second run line is slightly different. i had a version with both run line in the same file. but martong was worried that people running partial test would only not get all test relevant for what they were testing.

after through. ASTMerge requires both serialization and importing so it would probably be sufficient ?

[Tyker]

clang/include/clang/AST/APValue.h

659

We're horribly inconsistent in this class

this class has many flaws. but is far too broadly used to fix.

clang/include/clang/AST/ASTContext.h

293

the modification to use addDestruction() was made in a previous revision (https://reviews.llvm.org/D63376).
the use is currently on master in ConstantExpr::MoveIntoResult in the RSK_APValue case of the switch.
this is just a removing an unused member.

clang/include/clang/AST/TextNodeDumper.h

149 ↗

(On Diff #217600)

no worries, i wrote the original bug. i added APValue::dumpPretty which has almost the same output as APValue::printPretty but doesn't need an ASTContext. and is used for TextNodeDumper.

clang/lib/AST/APValue.cpp

874

this helper is not intended to be used outside of importing and serialization. it is logically part of initialization.
normal users are intended to use ArrayRef<APValue::LValuePathEntry> APValue::getLValuePath() const

clang/test/ASTMerge/APValue/APValue.cpp

2

it wasn't intentional, i added via git add i don't think i did anything weird. is it a problem ?

3–4

i don't know if it is normal. but i am getting an error hen i am not using -x c++
error: invalid argument '-std=gnu++2a' not allowed with 'C'

29

i don't intend to add them in this patch or subsequent patches. i don't know how to use the features that have these representations, i don't even know if they can be stored stored in that AST. so this is untested code.
that said theses representations aren't complex. the imporing for FixePoint, ComplexInt, ComplexFloat is a no-op and for AddrLabelDiff it is trivial. for serialization, I can put an llvm_unreachable to mark them as untested if you want ?

[aaron.ballman]

clang/include/clang/AST/APValue.h

659

Agreed -- I wasn't suggesting to fix the whole class, but just the new APIs that we add to the class. It looks like the private functions most consistently use a capital letter in this class, unfortunately. Best to stick with the local convention when in conflict.

clang/include/clang/AST/ASTContext.h

293

Ahhh, thank you for the explanation, I was missing that context.

clang/include/clang/AST/PrettyPrinter.h

203 ↗

(On Diff #221384)

Wether -> Whether

clang/lib/AST/APValue.cpp

649

Since you're touching the code anyway, this can be const auto *.

720

Are you sure this doesn't change behavior? See the implementation of ASTContext::getAsArrayType(). Same question applies below.

735

const auto * and same question about behavior changes.

874

Nothing about this API suggests that. The name looks like a generic getter. Perhaps a more descriptive name and some comments would help?

clang/test/ASTMerge/APValue/APValue.cpp

2

No idea; I'm on a platform where file modes are ignored. You should probably drop the svn property.

3–4

There's no %s on that line for the source file, which is why you get that diagnostic. I'm not certain what that RUN line does, actually -- it does an AST merge with... nothing... and then prints it out?

If that's intended, then you only need the -x c++ on that one RUN line.

29

I don't think llvm_unreachable makes a whole lot of sense unless the code is truly unreachable because there's no way to get an AST with that representation. By code inspection, the code looks reasonable but it does make me a bit uncomfortable to adopt it without tests. I suppose the FIXME is a reasonable compromise in this case, but if you have some spare cycles to investigate ways to get those representations, it would be appreciated.

[Tyker]

fixed most comments

clang/lib/AST/APValue.cpp

720

i ran the test suite after the change it there wasn't any test failures. but the test on dumping APValue are probably not as thorough as we would like them to be.
from analysis of ASTContext::getAsArrayType() the only effect i see on the element type is de-sugaring and canonicalization which shouldn't affect correctness of the output. de-sugaring requires the ASTContext but canonicalization doesn't.

i think the best way the have higher confidence is to ask rsmith what he thinks.

clang/test/ASTMerge/APValue/APValue.cpp

29

the reason i proposed llvm_unreachable was because it passes the tests and prevents future developer from depending on the code that depend on it assuming it works.

[aaron.ballman]

clang/include/clang/AST/APValue.h

663

ReserveVector

670

SetLValueEmptyPath

clang/lib/AST/APValue.cpp

720

Yeah, I doubt we have good test coverage for all the various behaviors here. I was wondering if the qualifiers bit was handled properly with a simple cast. @rsmith is a good person to weigh in.

clang/test/ASTMerge/APValue/APValue.cpp

29

We typically only use llvm_unreachable for situations where we believe the code path is impossible to reach, which is why I think that's the wrong approach. We could use an assertion to test the theory, however.

[Tyker]

made renamings

[rsmith]

clang/lib/AST/Expr.cpp

333

Can you use llvm_unreachable here? (Are there cases where we use RSK_None and then later find we actually have a value to store into the ConstantExpr?)

clang/lib/Serialization/ASTReader.cpp

9061

This is problematic.

ReadExpr will read a new copy of the expression, creating a distinct object. But in the case where we reach this when deserializing (for a MaterializeTemporaryExpr), we need to refer to the existing MaterializeTemporaryExpr in the initializer of its lifetime-extending declaration. We will also need to serialize the ASTContext's MaterializedTemporaryValues collection so that the temporaries lifetime-extended in a constant initializer get properly handled.

That all sounds very messy, so I think we should reconsider the model that we use for lifetime-extended materialized temporaries. As a half-baked idea:

• When we lifetime-extend a temporary, create a MaterializedTemporaryDecl to hold its value, and modify MaterializeTemporaryExpr to refer to the MaterializedTemporaryDecl rather than to just hold the subexpression for the temporary.
• Change the LValueBase representation to denote the declaration rather than the expression.
• Store the constant evaluated value for a materialized temporary on the MaterializedTemporaryDecl rather than on a side-table in the ASTContext.

With that done, we should verify that all remaining Expr*s used as LValueBases are either only transiently used during evaluation or don't have these kinds of identity problems.

[Tyker]

update done tasks.

clang/lib/AST/APValue.cpp

720

the original question we had is whether it is correct to replace Ctx.ASTContext::getAsArrayType(ElemTy) by cast<ArrayType>(ElemTy.getCanonicalType()) in this context and the other comment below.

clang/lib/AST/Expr.cpp

333

we can put llvm_unreachable in the switch because of if (!Value.hasValue()) above the switch but we can't remove if (!Value.hasValue()).
all cases i have seen where if (!Value.hasValue()) is taken occur after a semantic error occured.

clang/lib/Serialization/ASTReader.cpp

9061

Would it be possible to adapt serialization/deserialization so that they make sure that MaterializeTemporaryExpr are unique.
by:

• When serializing MaterializeTemporaryExpr serialize a key obtained from the pointer to the expression as it is unique.
• When deserializing MaterializeTemporaryExpr deserializing the key, and than have a cache for previously deserialized expression that need to be unique.

This would make easier adding new Expr that require uniqueness and seem less complicated.
What do you think ?

[Tyker]

ping @rsmith

[Tyker]

clang/lib/Serialization/ASTReader.cpp

9061

i added a review that does the refactoring https://reviews.llvm.org/D69360.

[Tyker]

now that the issue with uniqueness of expressions is solved. we should be able to keep going on that review @rsmith.
https://reviews.llvm.org/D63960 should be i think close to completion. so maybe for testing i could use immediate invocation as a source for ConstantExpr instead of the code i added to make constexpr variables emit ConstantExpr ?

[Tyker]

rebased

[rsmith]

Are we at a point where we can test this now? Perhaps by adding an assert in codegen that we always have an evaluated value for any constexpr variable that we emit?

clang/lib/Sema/SemaDecl.cpp

11883–11885 ↗

(On Diff #236707)

This may create additional AST nodes outside the ConstantExpr, which VarDecl::evaluateValue is not expecting to see (in particular, if we have cleanups for the initializer). Should the ConstantExpr go outside those nodes rather than inside?

clang/lib/Serialization/ASTReader.cpp

9061

What are the cases for which we still encounter expressions as lvalue bases during serialization? I think all the other ones should be OK, but maybe there's another interesting one we've overlooked.

[Tyker]

Sorry for the delay

In D63640#2151016, @rsmith wrote:

Are we at a point where we can test this now?

Yes we can use consteval to test it. so i removed changes to constexpr AST modling.

i split this path into 2 this path deal with serialization and importing, the other (D85144) improves the dumping of APValues to properly test this patch

[Tyker]

clang/lib/Sema/SemaDecl.cpp

11883–11885 ↗

(On Diff #236707)

i removed the changes to the storage of constexpr values since it was only used for testing purposes and we can now use consteval for that purpose.

clang/lib/Serialization/ASTReader.cpp

9061

the 2 example that come to mind are string literals and type_info there are probably more.

[Tyker]

rebased

[rsmith]

clang/include/clang/AST/APValue.h

660–662

Maybe something like this?

663

This function changes the size of the vector, so Reserve doesn't seem right to me. How about setVectorUninit? (Generally including Uninit in the names of the setters that leave things uninitialized would be useful.)

Also, instead of exposing GetInternal functions, how about adding functions that return a MutableArrayRef holding the array:

MutableArrayRef<APValue> setVectorUninit(unsigned N);
MutableArrayRef<LValuePathEntry> setLValueUninit(LValueBase B, const CharUnits &O, unsigned Size, bool OnePastTheEnd, bool IsNullPtr);
MutableArrayRef<const CXXRecordDecl*> MakeMemberPointerUninit(const ValueDecl *Member, bool IsDerivedMember, unsigned Size);

(It would be nice if MakeMemberPointer weren't so inconsistent with everything else this class does. But this whole interface is a mess.)

clang/lib/AST/APValue.cpp

941–947

Similarly maybe mentioning Uninit here would be useful.

clang/lib/AST/ASTImporter.cpp

6699–6701

Delete this commented-out code, please.

9038

We want the path in an APValue to be canonical, but importing a canonical decl might result in a non-canonical decl.

9058–9059

If you're intentionally not handling DynamicAllocLValue here (because those should always be transient), a comment to that effect would be useful.

9099

clang/lib/Serialization/ASTReader.cpp

8988–9106

You can assume here (and assert in the writer) that both floats in a ComplexFloat have the same fltSemantics.

9040

[Tyker]

addressed comments

[Tyker]

clang/lib/AST/ASTImporter.cpp

9038

but importing a canonical decl might result in a non-canonical decl.

this is a quite surprising behavior.

9058–9059

i added an asserts with a message.

[rsmith]

Looks great, thanks!

[martong]

Sorry for the late review, I just noticed something which is not a logical error, but we could make the ASTImporter code much cleaner.

clang/lib/AST/ASTImporter.cpp

9078–9089

A series of importChecked would result in a much cleaner code by omitting the second check. Also, instead of breaking out from the switch we can immediately return with the error.

This applies for the other cases where there are more import calls after each other (e.g. AddrLabelDiff, Union, ...).

Giving it more thought, you could use importChecked instead of Import everywhere in this function (for consistency).

[martong]

clang/lib/AST/ASTImporter.cpp

9038

but importing a canonical decl might result in a non-canonical decl.

this is a quite surprising behavior.

If you already have an existing redecl chain in the destination ASTContext (let's say A->B->C, A is the canonical decl), then importing a canonical decl (let's say D) would result an A->B->C->D' chain. Where D' is the imported version of D.

[rsmith]

Reverse ping: I have a patch implementing class type non-type template parameters that's blocked on this landing. If you won't have time to address @martong's comments soon, do you mind if I take this over and land it?

[martong]

In D63640#2331410, @rsmith wrote:

Reverse ping: I have a patch implementing class type non-type template parameters that's blocked on this landing. If you won't have time to address @martong's comments soon, do you mind if I take this over and land it?

It is okay for me to commit this patch in its current state. The changes I suggested could result in a cleaner code, but I can do those changes after we land this.

[Tyker]

try to apply martongs's suggestions.

[Tyker]

In D63640#2331734, @martong wrote:

In D63640#2331410, @rsmith wrote:

Reverse ping: I have a patch implementing class type non-type template parameters

that's blocked on this landing. If you won't have time to address @martong's comments soon, do you mind if I take this over and land it?

nice to see this coming.

It is okay for me to commit this patch in its current state. The changes I suggested could result in a cleaner code, but I can do those changes after we land this.

i couldn't apply martong's suggestion completely because importChecked is part of ASTNodeImporter not ASTImporter, but cleaned up some code.
but the "real" blocker is that the testing depends on D85144 for testing.
we could land it marking the tests XFAIL and correct it when dumping improvements arrive.

[martong]

In D63640#2331779, @Tyker wrote:

In D63640#2331734, @martong wrote:

In D63640#2331410, @rsmith wrote:

Reverse ping: I have a patch implementing class type non-type template parameters

that's blocked on this landing. If you won't have time to address @martong's comments soon, do you mind if I take this over and land it?

nice to see this coming.

It is okay for me to commit this patch in its current state. The changes I suggested could result in a cleaner code, but I can do those changes after we land this.

i couldn't apply martong's suggestion completely because importChecked is part of ASTNodeImporter not ASTImporter, but cleaned up some code.

This indicates that the newly added Import(APValue *) function should be part of the ASTNodeImporter. I came up with a draft patch on top of your patch:
https://github.com/llvm/llvm-project/commit/ac738cf854bdafa83a23c400bd5b2a90520566f9
You can see, this way we can eliminate some redundant ifs and casts.

[rsmith]

In D63640#2331779, @Tyker wrote:

but the "real" blocker is that the testing depends on D85144 for testing.
we could land it marking the tests XFAIL and correct it when dumping improvements arrive.

I'd be OK with that. We'll have coverage for this in various forms landing pretty soon.

[Tyker]

In D63640#2339917, @rsmith wrote:

In D63640#2331779, @Tyker wrote:

but the "real" blocker is that the testing depends on D85144 for testing.
we could land it marking the tests XFAIL and correct it when dumping improvements arrive.

I'd be OK with that. We'll have coverage for this in various forms landing pretty soon.

i appiled martong's patch and landed it marking the test as XFAIL.

clang/include/clang/AST/APValue.h

public:
     friend llvm::hash_code hash_value(LValuePathEntry A) {
       return llvm::hash_value(A.Value);
     }
   };
   struct NoLValuePath {};
   struct UninitArray {};
   struct UninitStruct {};
 
-  friend class ASTReader;
+  friend class ASTRecordReader;
   friend class ASTWriter;
+  friend class ASTImporter;
+  friend class ASTNodeImporter;
 
 private:
   ValueKind Kind;
 
   struct ComplexAPSInt {
     APSInt Real, Imag;
     ComplexAPSInt() : Real(1), Imag(1) {}
   };
public:
   void setFloat(APFloat F) {
     assert(isFloat() && "Invalid accessor");
     *(APFloat *)(char *)Data.buffer = std::move(F);
   }
   void setFixedPoint(APFixedPoint FX) {
     assert(isFixedPoint() && "Invalid accessor");
     *(APFixedPoint *)(char *)Data.buffer = std::move(FX);
   }
   void setVector(const APValue *E, unsigned N) {
-    assert(isVector() && "Invalid accessor");
-    ((Vec*)(char*)Data.buffer)->Elts = new APValue[N];
-    ((Vec*)(char*)Data.buffer)->NumElts = N;
+    MutableArrayRef<APValue> InternalElts = setVectorUninit(N);
     for (unsigned i = 0; i != N; ++i)
-      ((Vec*)(char*)Data.buffer)->Elts[i] = E[i];
+      InternalElts[i] = E[i];
   }
   void setComplexInt(APSInt R, APSInt I) {
     assert(R.getBitWidth() == I.getBitWidth() &&
            "Invalid complex int (type mismatch).");
     assert(isComplexInt() && "Invalid accessor");
     ((ComplexAPSInt *)(char *)Data.buffer)->Real = std::move(R);
     ((ComplexAPSInt *)(char *)Data.buffer)->Imag = std::move(I);
   }
   void setComplexFloat(APFloat R, APFloat I) {
     assert(&R.getSemantics() == &I.getSemantics() &&
            "Invalid complex float (type mismatch).");
     assert(isComplexFloat() && "Invalid accessor");
     ((ComplexAPFloat *)(char *)Data.buffer)->Real = std::move(R);
     ((ComplexAPFloat *)(char *)Data.buffer)->Imag = std::move(I);
   }
   void setLValue(LValueBase B, const CharUnits &O, NoLValuePath,
                  bool IsNullPtr);
   void setLValue(LValueBase B, const CharUnits &O,
                  ArrayRef<LValuePathEntry> Path, bool OnePastTheEnd,
                  bool IsNullPtr);
   void setUnion(const FieldDecl *Field, const APValue &Value) {
     assert(isUnion() && "Invalid accessor");
     ((UnionData*)(char*)Data.buffer)->Field = Field;
     *((UnionData*)(char*)Data.buffer)->Value = Value;
   }
   void setAddrLabelDiff(const AddrLabelExpr* LHSExpr,
                         const AddrLabelExpr* RHSExpr) {
     ((AddrLabelDiffData*)(char*)Data.buffer)->LHSExpr = LHSExpr;
private:
   }
   void MakeMemberPointer(const ValueDecl *Member, bool IsDerivedMember,
                          ArrayRef<const CXXRecordDecl*> Path);
   void MakeAddrLabelDiff() {
     assert(isAbsent() && "Bad state change");
     new ((void*)(char*)Data.buffer) AddrLabelDiffData();
     Kind = AddrLabelDiff;
   }
+
+private:
+  /// The following functions are used as part of initialization, during
+  /// deserialization and importing. Reserve the space so that it can be
+  /// filled in by those steps.
+  MutableArrayRef<APValue> setVectorUninit(unsigned N) {
+    assert(isVector() && "Invalid accessor");
+    Vec *V = ((Vec *)(char *)Data.buffer);
+    V->Elts = new APValue[N];
+    V->NumElts = N;
+    return {V->Elts, V->NumElts};
+  }
+  MutableArrayRef<LValuePathEntry>
+  setLValueUninit(LValueBase B, const CharUnits &O, unsigned Size,
+                  bool OnePastTheEnd, bool IsNullPtr);
+  MutableArrayRef<const CXXRecordDecl *>
+  setMemberPointerUninit(const ValueDecl *Member, bool IsDerivedMember,
+                         unsigned Size);
 };
 
 } // end namespace clang.
 
 namespace llvm {
 template<> struct DenseMapInfo<clang::APValue::LValueBase> {
   static clang::APValue::LValueBase getEmptyKey();
   static clang::APValue::LValueBase getTombstoneKey();
   static unsigned getHashValue(const clang::APValue::LValueBase &Base);
   static bool isEqual(const clang::APValue::LValueBase &LHS,
                       const clang::APValue::LValueBase &RHS);
 };
 }
 
 #endif

clang/include/clang/AST/ASTContext.h

class ASTContext : public RefCountedBase<ASTContext> {
   llvm::DenseMap<const ObjCMethodDecl*,const ObjCMethodDecl*> ObjCMethodRedecls;
 
   /// Mapping from __block VarDecls to BlockVarCopyInit.
   llvm::DenseMap<const VarDecl *, BlockVarCopyInit> BlockVarCopyInits;
 
   /// Mapping from GUIDs to the corresponding MSGuidDecl.
   mutable llvm::FoldingSet<MSGuidDecl> MSGuidDecls;
 
-  /// Used to cleanups APValues stored in the AST.
-  mutable llvm::SmallVector<APValue *, 0> APValueCleanups;
-
   /// A cache mapping a string value to a StringLiteral object with the same
   /// value.
   ///
   /// This is lazily created.  This is intentionally not serialized.
   mutable llvm::StringMap<StringLiteral *> StringLiteralCache;
 
   /// Representation of a "canonical" template template parameter that
   /// is used in canonical template names.

clang/include/clang/AST/ASTImporter.h

 //===- ASTImporter.h - Importing ASTs from other Contexts -------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file defines the ASTImporter class which imports AST nodes from one
 //  context into another context.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_AST_ASTIMPORTER_H
 #define LLVM_CLANG_AST_ASTIMPORTER_H
 
+#include "clang/AST/APValue.h"
 #include "clang/AST/DeclBase.h"
 #include "clang/AST/DeclarationName.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/NestedNameSpecifier.h"
 #include "clang/AST/TemplateName.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/IdentifierTable.h"
public:
 
     /// Import the given CXXBaseSpecifier from the "from" context into
     /// the "to" context.
     ///
     /// \returns The equivalent CXXBaseSpecifier in the source manager of the
     /// "to" context, or the import error.
     llvm::Expected<CXXBaseSpecifier *> Import(const CXXBaseSpecifier *FromSpec);
 
+    /// Import the given APValue from the "from" context into
+    /// the "to" context.
+    ///
+    /// \return the equivalent APValue in the "to" context or the import
+    /// error.
+    llvm::Expected<APValue> Import(const APValue &FromValue);
+
     /// Import the definition of the given declaration, including all of
     /// the declarations it contains.
     LLVM_NODISCARD llvm::Error ImportDefinition(Decl *From);
 
     /// Cope with a name conflict when importing a declaration into the
     /// given context.
     ///
     /// This routine is invoked whenever there is a name conflict while

clang/lib/AST/APValue.cpp

struct MemberPointerBase {
     unsigned PathLength;
   };
 }
 
 struct APValue::MemberPointerData : MemberPointerBase {
   static const unsigned InlinePathSpace =
       (DataSize - sizeof(MemberPointerBase)) / sizeof(const CXXRecordDecl*);
   typedef const CXXRecordDecl *PathElem;
   union {
     PathElem Path[InlinePathSpace];
     PathElem *PathPtr;
   };
 
   MemberPointerData() { PathLength = 0; }
   ~MemberPointerData() { resizePath(0); }
 
   void resizePath(unsigned Length) {
if (!hasLValuePath()) {
           Out << "(char*)";
           S = CharUnits::One();
         }
         Out << '&';
       } else if (!IsReference) {
         Out << '&';
       }
 
       if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
         Out << *VD;
       else if (TypeInfoLValue TI = Base.dyn_cast<TypeInfoLValue>()) {
         TI.print(Out, Ctx.getPrintingPolicy());
       } else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
         Out << "{*new "
             << Base.getDynamicAllocType().stream(Ctx.getPrintingPolicy()) << "#"
             << DA.getIndex() << "}";
       } else {
for (unsigned I = 0, N = Path.size(); I != N; ++I) {
           if (CastToBase)
             Out << *CastToBase << "::";
           Out << *VD;
           ElemTy = VD->getType();
         }
       } else {
         // The lvalue must refer to an array.
         Out << '[' << Path[I].getAsArrayIndex() << ']';
         ElemTy = Ctx.getAsArrayType(ElemTy)->getElementType();
       }
     }
 
     // Handle formatting of one-past-the-end lvalues.
     if (isLValueOnePastTheEnd()) {
       // FIXME: If CastToBase is non-0, we should prefix the output with
       // "(CastToBase*)".
       Out << " + 1";
       if (IsReference)
         Out << ')';
     }
     return;
   }
   case APValue::Array: {
     const ArrayType *AT = Ctx.getAsArrayType(Ty);
     QualType ElemTy = AT->getElementType();
     Out << '{';
     if (unsigned N = getArrayInitializedElts()) {
       getArrayInitializedElt(0).printPretty(Out, Ctx, ElemTy);
       for (unsigned I = 1; I != N; ++I) {
         Out << ", ";
         if (I == 10) {
           // Avoid printing out the entire contents of large arrays.
unsigned APValue::getLValueVersion() const {
   return ((const LV*)(const char*)Data.buffer)->Base.getVersion();
 }
 
 bool APValue::isNullPointer() const {
   assert(isLValue() && "Invalid usage");
   return ((const LV*)(const char*)Data.buffer)->IsNullPtr;
 }
 
 void APValue::setLValue(LValueBase B, const CharUnits &O, NoLValuePath,
                         bool IsNullPtr) {
   assert(isLValue() && "Invalid accessor");
   LV &LVal = *((LV*)(char*)Data.buffer);
   LVal.Base = B;
   LVal.IsOnePastTheEnd = false;
   LVal.Offset = O;
   LVal.resizePath((unsigned)-1);
   LVal.IsNullPtr = IsNullPtr;
 }
 
-void APValue::setLValue(LValueBase B, const CharUnits &O,
-                        ArrayRef<LValuePathEntry> Path, bool IsOnePastTheEnd,
-                        bool IsNullPtr) {
+MutableArrayRef<APValue::LValuePathEntry>
+APValue::setLValueUninit(LValueBase B, const CharUnits &O, unsigned Size,
+                         bool IsOnePastTheEnd, bool IsNullPtr) {
   assert(isLValue() && "Invalid accessor");
-  LV &LVal = *((LV*)(char*)Data.buffer);
+  LV &LVal = *((LV *)(char *)Data.buffer);
   LVal.Base = B;
   LVal.IsOnePastTheEnd = IsOnePastTheEnd;
   LVal.Offset = O;
-  LVal.resizePath(Path.size());
-  memcpy(LVal.getPath(), Path.data(), Path.size() * sizeof(LValuePathEntry));
   LVal.IsNullPtr = IsNullPtr;
+  LVal.resizePath(Size);
+  return {LVal.getPath(), Size};
+}
+
+void APValue::setLValue(LValueBase B, const CharUnits &O,
+                        ArrayRef<LValuePathEntry> Path, bool IsOnePastTheEnd,
+                        bool IsNullPtr) {
+  MutableArrayRef<APValue::LValuePathEntry> InternalPath =
+      setLValueUninit(B, O, Path.size(), IsOnePastTheEnd, IsNullPtr);
+  memcpy(InternalPath.data(), Path.data(),
+         Path.size() * sizeof(LValuePathEntry));
 }
 
 const ValueDecl *APValue::getMemberPointerDecl() const {
   assert(isMemberPointer() && "Invalid accessor");
   const MemberPointerData &MPD =
       *((const MemberPointerData *)(const char *)Data.buffer);
   return MPD.MemberAndIsDerivedMember.getPointer();
 }

 }
 
 void APValue::MakeArray(unsigned InitElts, unsigned Size) {
   assert(isAbsent() && "Bad state change");
   new ((void*)(char*)Data.buffer) Arr(InitElts, Size);
   Kind = Array;
 }
 
-void APValue::MakeMemberPointer(const ValueDecl *Member, bool IsDerivedMember,
-                                ArrayRef<const CXXRecordDecl*> Path) {
+MutableArrayRef<APValue::LValuePathEntry>
+setLValueUninit(APValue::LValueBase B, const CharUnits &O, unsigned Size,
+                bool OnePastTheEnd, bool IsNullPtr);
+
+MutableArrayRef<const CXXRecordDecl *>
+APValue::setMemberPointerUninit(const ValueDecl *Member, bool IsDerivedMember,
+                                unsigned Size) {
   assert(isAbsent() && "Bad state change");
-  MemberPointerData *MPD = new ((void*)(char*)Data.buffer) MemberPointerData;
+  MemberPointerData *MPD = new ((void *)(char *)Data.buffer) MemberPointerData;
   Kind = MemberPointer;
   MPD->MemberAndIsDerivedMember.setPointer(
       Member ? cast<ValueDecl>(Member->getCanonicalDecl()) : nullptr);
   MPD->MemberAndIsDerivedMember.setInt(IsDerivedMember);
-  MPD->resizePath(Path.size());
+  MPD->resizePath(Size);
+  return {MPD->getPath(), MPD->PathLength};
+}
+
+void APValue::MakeMemberPointer(const ValueDecl *Member, bool IsDerivedMember,
+                                ArrayRef<const CXXRecordDecl *> Path) {
+  MutableArrayRef<const CXXRecordDecl *> InternalPath =
+      setMemberPointerUninit(Member, IsDerivedMember, Path.size());
   for (unsigned I = 0; I != Path.size(); ++I)
-    MPD->getPath()[I] = Path[I]->getCanonicalDecl();
+    InternalPath[I] = Path[I]->getCanonicalDecl();
 }

clang/lib/AST/ASTContext.cpp

ASTContext::~ASTContext() {
 
   for (llvm::DenseMap<const Decl*, AttrVec*>::iterator A = DeclAttrs.begin(),
                                                     AEnd = DeclAttrs.end();
        A != AEnd; ++A)
     A->second->~AttrVec();
 
   for (const auto &Value : ModuleInitializers)
     Value.second->~PerModuleInitializers();
-
-  for (APValue *Value : APValueCleanups)
-    Value->~APValue();
 }
 
 void ASTContext::setTraversalScope(const std::vector<Decl *> &TopLevelDecls) {
   TraversalScope = TopLevelDecls;
   getParentMapContext().clear();
 }
 
 void ASTContext::AddDeallocation(void (*Callback)(void *), void *Data) const {

clang/lib/AST/ASTImporter.cpp

public:
     Error ImportDeclarationNameLoc(
         const DeclarationNameInfo &From, DeclarationNameInfo &To);
     Error ImportDeclContext(DeclContext *FromDC, bool ForceImport = false);
     Error ImportDeclContext(
         Decl *From, DeclContext *&ToDC, DeclContext *&ToLexicalDC);
     Error ImportImplicitMethods(const CXXRecordDecl *From, CXXRecordDecl *To);
 
     Expected<CXXCastPath> ImportCastPath(CastExpr *E);
+    Expected<APValue> ImportAPValue(const APValue &FromValue);
 
     using Designator = DesignatedInitExpr::Designator;
 
     /// What we should import from the definition.
     enum ImportDefinitionKind {
       /// Import the default subset of the definition, which might be
       /// nothing (if minimal import is set) or might be everything (if minimal
       /// import is not set).
if (Err)
     return std::move(Err);
 
   return new (Importer.getToContext()) AddrLabelExpr(
       ToAmpAmpLoc, ToLabelLoc, ToLabel, ToType);
 }
 ExpectedStmt ASTNodeImporter::VisitConstantExpr(ConstantExpr *E) {
   Error Err = Error::success();
   auto ToSubExpr = importChecked(Err, E->getSubExpr());
+  auto ToResult = importChecked(Err, E->getAPValueResult());
   if (Err)
     return std::move(Err);
 
-  // TODO : Handle APValue::ValueKind that require importing.
-
-  APValue::ValueKind Kind = E->getResultAPValueKind();
-  if (Kind == APValue::Int || Kind == APValue::Float ||
-      Kind == APValue::FixedPoint || Kind == APValue::ComplexFloat ||
-      Kind == APValue::ComplexInt)
-    return ConstantExpr::Create(Importer.getToContext(), ToSubExpr,
-                                E->getAPValueResult());
-  return ConstantExpr::Create(Importer.getToContext(), ToSubExpr);
+  return ConstantExpr::Create(Importer.getToContext(), ToSubExpr, ToResult);
 }
 ExpectedStmt ASTNodeImporter::VisitParenExpr(ParenExpr *E) {
   Error Err = Error::success();
   auto ToLParen = importChecked(Err, E->getLParen());
   auto ToRParen = importChecked(Err, E->getRParen());
   auto ToSubExpr = importChecked(Err, E->getSubExpr());
   if (Err)
     return std::move(Err);
 
if (!ToEllipsisLoc)
     return ToEllipsisLoc.takeError();
   CXXBaseSpecifier *Imported = new (ToContext) CXXBaseSpecifier(
       *ToSourceRange, BaseSpec->isVirtual(), BaseSpec->isBaseOfClass(),
       BaseSpec->getAccessSpecifierAsWritten(), *ToTSI, *ToEllipsisLoc);
   ImportedCXXBaseSpecifiers[BaseSpec] = Imported;
   return Imported;
 }
 
+llvm::Expected<APValue> ASTImporter::Import(const APValue &FromValue) {
+  ASTNodeImporter Importer(*this);
+  return Importer.ImportAPValue(FromValue);
+}
+
 Error ASTImporter::ImportDefinition(Decl *From) {
   ExpectedDecl ToOrErr = Import(From);
   if (!ToOrErr)
     return ToOrErr.takeError();
   Decl *To = *ToOrErr;
 
   auto *FromDC = cast<DeclContext>(From);
   ASTNodeImporter Importer(*this);
Expected<Selector> ASTImporter::Import(Selector FromSel) {
 
   SmallVector<IdentifierInfo *, 4> Idents;
   Idents.push_back(Import(FromSel.getIdentifierInfoForSlot(0)));
   for (unsigned I = 1, N = FromSel.getNumArgs(); I < N; ++I)
     Idents.push_back(Import(FromSel.getIdentifierInfoForSlot(I)));
   return ToContext.Selectors.getSelector(FromSel.getNumArgs(), Idents.data());
 }
 
+llvm::Expected<APValue>
+ASTNodeImporter::ImportAPValue(const APValue &FromValue) {
+  APValue Result;
+  llvm::Error Err = llvm::Error::success();
+  auto ImportLoop = [&](const APValue *From, APValue *To, unsigned Size) {
+    for (unsigned Idx = 0; Idx < Size; Idx++) {
+      APValue Tmp = importChecked(Err, From[Idx]);
+      To[Idx] = Tmp;
+    }
+  };
+  switch (FromValue.getKind()) {
+  case APValue::None:
+  case APValue::Indeterminate:
+  case APValue::Int:
+  case APValue::Float:
+  case APValue::FixedPoint:
+  case APValue::ComplexInt:
+  case APValue::ComplexFloat:
+    Result = FromValue;
+    break;
+  case APValue::Vector: {
+    Result.MakeVector();
+    MutableArrayRef<APValue> Elts =
+        Result.setVectorUninit(FromValue.getVectorLength());
+    ImportLoop(
+        ((const APValue::Vec *)(const char *)FromValue.Data.buffer)->Elts,
+        Elts.data(), FromValue.getVectorLength());
+    break;
+  }
+  case APValue::Array:
+    Result.MakeArray(FromValue.getArrayInitializedElts(),
+                     FromValue.getArraySize());
+    ImportLoop(
+        ((const APValue::Arr *)(const char *)FromValue.Data.buffer)->Elts,
+        ((const APValue::Arr *)(const char *)Result.Data.buffer)->Elts,
+        FromValue.getArrayInitializedElts());
+    break;
+  case APValue::Struct:
+    Result.MakeStruct(FromValue.getStructNumBases(),
+                      FromValue.getStructNumFields());
+    ImportLoop(
+        ((const APValue::StructData *)(const char *)FromValue.Data.buffer)
+            ->Elts,
+        ((const APValue::StructData *)(const char *)Result.Data.buffer)->Elts,
+        FromValue.getStructNumBases() + FromValue.getStructNumFields());
+    break;
+  case APValue::Union: {
+    Result.MakeUnion();
+    const Decl *ImpFDecl = importChecked(Err, FromValue.getUnionField());
+    APValue ImpValue = importChecked(Err, FromValue.getUnionValue());
+    if (Err)
+      return std::move(Err);
+    Result.setUnion(cast<FieldDecl>(ImpFDecl), ImpValue);
+    break;
+  }
+  case APValue::AddrLabelDiff: {
+    Result.MakeAddrLabelDiff();
+    const Expr *ImpLHS = importChecked(Err, FromValue.getAddrLabelDiffLHS());
+    const Expr *ImpRHS = importChecked(Err, FromValue.getAddrLabelDiffRHS());
+    if (Err)
+      return std::move(Err);
+    Result.setAddrLabelDiff(cast<AddrLabelExpr>(ImpLHS),
+                            cast<AddrLabelExpr>(ImpRHS));
+    break;
+  }
+  case APValue::MemberPointer: {
+    const Decl *ImpMemPtrDecl =
+        importChecked(Err, FromValue.getMemberPointerDecl());
+    if (Err)
+      return std::move(Err);
+    MutableArrayRef<const CXXRecordDecl *> ToPath =
+        Result.setMemberPointerUninit(
+            cast<const ValueDecl>(ImpMemPtrDecl),
+            FromValue.isMemberPointerToDerivedMember(),
+            FromValue.getMemberPointerPath().size());
+    llvm::ArrayRef<const CXXRecordDecl *> FromPath =
+        Result.getMemberPointerPath();
+    for (unsigned Idx = 0; Idx < FromValue.getMemberPointerPath().size();
+         Idx++) {
+      const Decl *ImpDecl = importChecked(Err, FromPath[Idx]);
+      if (Err)
+        return std::move(Err);
+      ToPath[Idx] = cast<const CXXRecordDecl>(ImpDecl->getCanonicalDecl());
+    }
+    break;
+  }
+  case APValue::LValue:
+    APValue::LValueBase Base;
+    QualType FromElemTy;
+    if (FromValue.getLValueBase()) {
+      assert(!FromValue.getLValueBase().is<DynamicAllocLValue>() &&
+             "in C++20 dynamic allocation are transient so they shouldn't "
+             "appear in the AST");
+      if (!FromValue.getLValueBase().is<TypeInfoLValue>()) {
+        if (const auto *E =
+                FromValue.getLValueBase().dyn_cast<const Expr *>()) {
+          FromElemTy = E->getType();
+          const Expr *ImpExpr = importChecked(Err, E);
+          if (Err)
+            return std::move(Err);
+          Base = APValue::LValueBase(ImpExpr,
+                                     FromValue.getLValueBase().getCallIndex(),
+                                     FromValue.getLValueBase().getVersion());
+        } else {
+          FromElemTy =
+              FromValue.getLValueBase().get<const ValueDecl *>()->getType();
+          const Decl *ImpDecl = importChecked(
+              Err, FromValue.getLValueBase().get<const ValueDecl *>());
+          if (Err)
+            return std::move(Err);
+          Base = APValue::LValueBase(cast<ValueDecl>(ImpDecl),
+                                     FromValue.getLValueBase().getCallIndex(),
+                                     FromValue.getLValueBase().getVersion());
+        }
+      } else {
+        FromElemTy = FromValue.getLValueBase().getTypeInfoType();
+        QualType ImpTypeInfo = importChecked(
+            Err,
+            QualType(FromValue.getLValueBase().get<TypeInfoLValue>().getType(),
+                     0));
+        QualType ImpType =
+            importChecked(Err, FromValue.getLValueBase().getTypeInfoType());
+        if (Err)
+          return std::move(Err);
+        Base = APValue::LValueBase::getTypeInfo(
+            TypeInfoLValue(ImpTypeInfo.getTypePtr()), ImpType);
+      }
+    }
+    CharUnits Offset = FromValue.getLValueOffset();
+    unsigned PathLength = FromValue.getLValuePath().size();
+    Result.MakeLValue();
+    if (FromValue.hasLValuePath()) {
+      MutableArrayRef<APValue::LValuePathEntry> ToPath = Result.setLValueUninit(
+          Base, Offset, PathLength, FromValue.isLValueOnePastTheEnd(),
+          FromValue.isNullPointer());
+      llvm::ArrayRef<APValue::LValuePathEntry> FromPath =
+          FromValue.getLValuePath();
+      for (unsigned LoopIdx = 0; LoopIdx < PathLength; LoopIdx++) {
+        if (FromElemTy->isRecordType()) {
+          const Decl *FromDecl =
+              FromPath[LoopIdx].getAsBaseOrMember().getPointer();
+          const Decl *ImpDecl = importChecked(Err, FromDecl);
+          if (Err)
+            return std::move(Err);
+          if (auto *RD = dyn_cast<CXXRecordDecl>(FromDecl))
+            FromElemTy = Importer.FromContext.getRecordType(RD);
+          else
+            FromElemTy = cast<ValueDecl>(FromDecl)->getType();
+          ToPath[LoopIdx] = APValue::LValuePathEntry(APValue::BaseOrMemberType(
+              ImpDecl, FromPath[LoopIdx].getAsBaseOrMember().getInt()));
+        } else {
+          FromElemTy =
+              Importer.FromContext.getAsArrayType(FromElemTy)->getElementType();
+          ToPath[LoopIdx] = APValue::LValuePathEntry::ArrayIndex(
+              FromPath[LoopIdx].getAsArrayIndex());
+        }
+      }
+    } else
+      Result.setLValue(Base, Offset, APValue::NoLValuePath{},
+                       FromValue.isNullPointer());
+  }
+  if (Err)
+    return std::move(Err);
+  return Result;
+}
+
 Expected<DeclarationName> ASTImporter::HandleNameConflict(DeclarationName Name,
                                                           DeclContext *DC,
                                                           unsigned IDNS,
                                                           NamedDecl **Decls,
                                                           unsigned NumDecls) {
   if (ODRHandling == ODRHandlingType::Conservative)
     // Report error at any name conflict.
     return make_error<ImportError>(ImportError::NameConflict);
if (Pos != ImportedDecls.end())
     return Pos->second;
   ImportedDecls[From] = To;
   // This mapping should be maintained only in this function. Therefore do not
   // check for additional consistency.
   ImportedFromDecls[To] = From;
   AddToLookupTable(To);
   return To;
 }
 
 llvm::Optional<ImportError>
 ASTImporter::getImportDeclErrorIfAny(Decl *FromD) const {
   auto Pos = ImportDeclErrors.find(FromD);
   if (Pos != ImportDeclErrors.end())
     return Pos->second;
   else
     return Optional<ImportError>();
 }
 
 void ASTImporter::setImportDeclError(Decl *From, ImportError Error) {
   auto InsertRes = ImportDeclErrors.insert({From, Error});
   (void)InsertRes;
   // Either we set the error for the first time, or we already had set one and

clang/lib/AST/Expr.cpp

 }
 
 void ConstantExpr::MoveIntoResult(APValue &Value, const ASTContext &Context) {
   assert((unsigned)getStorageKind(Value) <= ConstantExprBits.ResultKind &&
          "Invalid storage for this value kind");
   ConstantExprBits.APValueKind = Value.getKind();
   switch (ConstantExprBits.ResultKind) {
   case RSK_None:
     return;
   case RSK_Int64:
     Int64Result() = *Value.getInt().getRawData();
     ConstantExprBits.BitWidth = Value.getInt().getBitWidth();
     ConstantExprBits.IsUnsigned = Value.getInt().isUnsigned();
     return;
   case RSK_APValue:
     if (!ConstantExprBits.HasCleanup && Value.needsCleanup()) {
       ConstantExprBits.HasCleanup = true;
case ConstantExpr::RSK_Int64:
     return llvm::APSInt(llvm::APInt(ConstantExprBits.BitWidth, Int64Result()),
                         ConstantExprBits.IsUnsigned);
   default:
     llvm_unreachable("invalid Accessor");
   }
 }
 
 APValue ConstantExpr::getAPValueResult() const {
-  assert(hasAPValueResult());
 
   switch (ConstantExprBits.ResultKind) {
   case ConstantExpr::RSK_APValue:
     return APValueResult();
   case ConstantExpr::RSK_Int64:
     return APValue(
         llvm::APSInt(llvm::APInt(ConstantExprBits.BitWidth, Int64Result()),
                      ConstantExprBits.IsUnsigned));
   case ConstantExpr::RSK_None:
+    if (ConstantExprBits.APValueKind == APValue::Indeterminate)
+      return APValue::IndeterminateValue();
     return APValue();
   }
   llvm_unreachable("invalid ResultKind");
 }
 
 DeclRefExpr::DeclRefExpr(const ASTContext &Ctx, ValueDecl *D,
                          bool RefersToEnclosingVariableOrCapture, QualType T,
                          ExprValueKind VK, SourceLocation L,

clang/lib/Serialization/ASTReader.cpp

ReadFixedPointSemantics(const SmallVectorImpl<uint64_t> &Record,
   uint64_t Tmp = Record[Idx++];
   bool IsSigned = Tmp & 0x1;
   bool IsSaturated = Tmp & 0x2;
   bool HasUnsignedPadding = Tmp & 0x4;
   return llvm::FixedPointSemantics(Width, Scale, IsSigned, IsSaturated,
                                    HasUnsignedPadding);
 }
 
-static const llvm::fltSemantics &
-readAPFloatSemantics(ASTRecordReader &reader) {
-  return llvm::APFloatBase::EnumToSemantics(
-    static_cast<llvm::APFloatBase::Semantics>(reader.readInt()));
-}
-
 APValue ASTRecordReader::readAPValue() {
-  unsigned Kind = readInt();
-  switch ((APValue::ValueKind) Kind) {
+  auto Kind = static_cast<APValue::ValueKind>(asImpl().readUInt32());
+  switch (Kind) {
   case APValue::None:
     return APValue();
   case APValue::Indeterminate:
     return APValue::IndeterminateValue();
   case APValue::Int:
-    return APValue(readAPSInt());
+    return APValue(asImpl().readAPSInt());
   case APValue::Float: {
-    const llvm::fltSemantics &FloatSema = readAPFloatSemantics(*this);
-    return APValue(readAPFloat(FloatSema));
+    const llvm::fltSemantics &FloatSema = llvm::APFloatBase::EnumToSemantics(
+        static_cast<llvm::APFloatBase::Semantics>(asImpl().readUInt32()));
+    return APValue(asImpl().readAPFloat(FloatSema));
   }
   case APValue::FixedPoint: {
     llvm::FixedPointSemantics FPSema = ReadFixedPointSemantics(Record, Idx);
     return APValue(llvm::APFixedPoint(readAPInt(), FPSema));
   }
   case APValue::ComplexInt: {
-    llvm::APSInt First = readAPSInt();
-    return APValue(std::move(First), readAPSInt());
+    llvm::APSInt First = asImpl().readAPSInt();
+    return APValue(std::move(First), asImpl().readAPSInt());
   }
   case APValue::ComplexFloat: {
-    const llvm::fltSemantics &FloatSema1 = readAPFloatSemantics(*this);
-    llvm::APFloat First = readAPFloat(FloatSema1);
-    const llvm::fltSemantics &FloatSema2 = readAPFloatSemantics(*this);
-    return APValue(std::move(First), readAPFloat(FloatSema2));
-  }
-  case APValue::LValue:
-  case APValue::Vector:
-  case APValue::Array:
-  case APValue::Struct:
-  case APValue::Union:
-  case APValue::MemberPointer:
-  case APValue::AddrLabelDiff:
-    // TODO : Handle all these APValue::ValueKind.
-    return APValue();
+    const llvm::fltSemantics &FloatSema = llvm::APFloatBase::EnumToSemantics(
+        static_cast<llvm::APFloatBase::Semantics>(asImpl().readUInt32()));
+    llvm::APFloat First = readAPFloat(FloatSema);
+    return APValue(std::move(First), asImpl().readAPFloat(FloatSema));
+  }
+  case APValue::Vector: {
+    APValue Result;
+    Result.MakeVector();
+    unsigned Length = asImpl().readUInt32();
+    (void)Result.setVectorUninit(Length);
+    for (unsigned LoopIdx = 0; LoopIdx < Length; LoopIdx++)
+      Result.getVectorElt(LoopIdx) = asImpl().readAPValue();
+    return Result;
+  }
+  case APValue::Array: {
+    APValue Result;
+    unsigned InitLength = asImpl().readUInt32();
+    unsigned TotalLength = asImpl().readUInt32();
+    Result.MakeArray(InitLength, TotalLength);
+    for (unsigned LoopIdx = 0; LoopIdx < InitLength; LoopIdx++)
+      Result.getArrayInitializedElt(LoopIdx) = asImpl().readAPValue();
+    return Result;
+  }
+  case APValue::Struct: {
+    APValue Result;
+    unsigned BasesLength = asImpl().readUInt32();
+    unsigned FieldsLength = asImpl().readUInt32();
+    Result.MakeStruct(BasesLength, FieldsLength);
+    for (unsigned LoopIdx = 0; LoopIdx < BasesLength; LoopIdx++)
+      Result.getStructBase(LoopIdx) = asImpl().readAPValue();
+    for (unsigned LoopIdx = 0; LoopIdx < FieldsLength; LoopIdx++)
+      Result.getStructField(LoopIdx) = asImpl().readAPValue();
+    return Result;
+  }
+  case APValue::Union: {
+    auto *FDecl = asImpl().readDeclAs<FieldDecl>();
+    APValue Value = asImpl().readAPValue();
+    return APValue(FDecl, std::move(Value));
+  }
+  case APValue::AddrLabelDiff: {
+    auto *LHS = cast<AddrLabelExpr>(asImpl().readExpr());
+    auto *RHS = cast<AddrLabelExpr>(asImpl().readExpr());
+    return APValue(LHS, RHS);
+  }
+  case APValue::MemberPointer: {
+    APValue Result;
+    bool IsDerived = asImpl().readUInt32();
+    auto *Member = asImpl().readDeclAs<ValueDecl>();
+    unsigned PathSize = asImpl().readUInt32();
+    const CXXRecordDecl **PathArray =
+        Result.setMemberPointerUninit(Member, IsDerived, PathSize).data();
+    for (unsigned LoopIdx = 0; LoopIdx < PathSize; LoopIdx++)
+      PathArray[LoopIdx] =
+          asImpl().readDeclAs<const CXXRecordDecl>()->getCanonicalDecl();
+    return Result;
+  }
+  case APValue::LValue: {
+    uint64_t Bits = asImpl().readUInt32();
+    bool HasLValuePath = Bits & 0x1;
+    bool IsLValueOnePastTheEnd = Bits & 0x2;
+    bool IsExpr = Bits & 0x4;
+    bool IsTypeInfo = Bits & 0x8;
+    bool IsNullPtr = Bits & 0x10;
+    bool HasBase = Bits & 0x20;
+    APValue::LValueBase Base;
+    QualType ElemTy;
+    assert((!IsExpr || !IsTypeInfo) && "LValueBase cannot be both");
+    if (HasBase) {
+      if (!IsTypeInfo) {
+        unsigned CallIndex = asImpl().readUInt32();
+        unsigned Version = asImpl().readUInt32();
+        if (IsExpr) {
+          Base = APValue::LValueBase(asImpl().readExpr(), CallIndex, Version);
+          ElemTy = Base.get<const Expr *>()->getType();
+        } else {
+          Base = APValue::LValueBase(asImpl().readDeclAs<const ValueDecl>(),
+                                     CallIndex, Version);
+          ElemTy = Base.get<const ValueDecl *>()->getType();
+        }
+      } else {
+        QualType TypeInfo = asImpl().readType();
+        QualType Type = asImpl().readType();
+        Base = APValue::LValueBase::getTypeInfo(
+            TypeInfoLValue(TypeInfo.getTypePtr()), Type);
+        Base.getTypeInfoType();
+      }
+    }
+    CharUnits Offset = CharUnits::fromQuantity(asImpl().readUInt32());
+    unsigned PathLength = asImpl().readUInt32();
+    APValue Result;
+    Result.MakeLValue();
+    if (HasLValuePath) {
+      APValue::LValuePathEntry *Path =
+          Result
+              .setLValueUninit(Base, Offset, PathLength, IsLValueOnePastTheEnd,
+                               IsNullPtr)
+              .data();
+      for (unsigned LoopIdx = 0; LoopIdx < PathLength; LoopIdx++) {
+        if (ElemTy->getAs<RecordType>()) {
+          unsigned Int = asImpl().readUInt32();
+          Decl *D = asImpl().readDeclAs<Decl>();
+          if (auto *RD = dyn_cast<CXXRecordDecl>(D))
+            ElemTy = getASTContext().getRecordType(RD);
+          else
+            ElemTy = cast<ValueDecl>(D)->getType();
+          Path[LoopIdx] =
+              APValue::LValuePathEntry(APValue::BaseOrMemberType(D, Int));
+        } else {
+          ElemTy = getASTContext().getAsArrayType(ElemTy)->getElementType();
+          Path[LoopIdx] =
+              APValue::LValuePathEntry::ArrayIndex(asImpl().readUInt32());
+        }
+      }
+    } else
+      Result.setLValue(Base, Offset, APValue::NoLValuePath{}, IsNullPtr);
+    return Result;
+  }
   }
   llvm_unreachable("Invalid APValue::ValueKind");
 }
 
 /// Read a floating-point value
 llvm::APFloat ASTRecordReader::readAPFloat(const llvm::fltSemantics &Sem) {
   return llvm::APFloat(Sem, readAPInt());
 }
 

clang/lib/Serialization/ASTWriter.cpp

case APValue::FixedPoint: {
     return;
   }
   case APValue::ComplexInt: {
     AddAPSInt(Value.getComplexIntReal());
     AddAPSInt(Value.getComplexIntImag());
     return;
   }
   case APValue::ComplexFloat: {
+    assert(llvm::APFloatBase::SemanticsToEnum(
+               Value.getComplexFloatImag().getSemantics()) ==
+           llvm::APFloatBase::SemanticsToEnum(
+               Value.getComplexFloatReal().getSemantics()));
     push_back(static_cast<uint64_t>(llvm::APFloatBase::SemanticsToEnum(
         Value.getComplexFloatReal().getSemantics())));
     AddAPFloat(Value.getComplexFloatReal());
-    push_back(static_cast<uint64_t>(llvm::APFloatBase::SemanticsToEnum(
-        Value.getComplexFloatImag().getSemantics())));
     AddAPFloat(Value.getComplexFloatImag());
     return;
   }
-  case APValue::LValue:
   case APValue::Vector:
+    push_back(Value.getVectorLength());
+    for (unsigned Idx = 0; Idx < Value.getVectorLength(); Idx++)
+      AddAPValue(Value.getVectorElt(Idx));
+    return;
   case APValue::Array:
+    push_back(Value.getArrayInitializedElts());
+    push_back(Value.getArraySize());
+    for (unsigned Idx = 0; Idx < Value.getArrayInitializedElts(); Idx++)
+      AddAPValue(Value.getArrayInitializedElt(Idx));
+    return;
   case APValue::Struct:
+    push_back(Value.getStructNumBases());
+    push_back(Value.getStructNumFields());
+    for (unsigned Idx = 0; Idx < Value.getStructNumBases(); Idx++)
+      AddAPValue(Value.getStructBase(Idx));
+    for (unsigned Idx = 0; Idx < Value.getStructNumFields(); Idx++)
+      AddAPValue(Value.getStructField(Idx));
+    return;
   case APValue::Union:
-  case APValue::MemberPointer:
+    AddDeclRef(Value.getUnionField());
+    AddAPValue(Value.getUnionValue());
+    return;
   case APValue::AddrLabelDiff:
-    // TODO : Handle all these APValue::ValueKind.
+    AddStmt(const_cast<AddrLabelExpr *>(Value.getAddrLabelDiffLHS()));
+    AddStmt(const_cast<AddrLabelExpr *>(Value.getAddrLabelDiffRHS()));
+    return;
+  case APValue::MemberPointer: {
+    push_back(Value.isMemberPointerToDerivedMember());
+    AddDeclRef(Value.getMemberPointerDecl());
+    ArrayRef<const CXXRecordDecl *> RecordPath = Value.getMemberPointerPath();
+    push_back(RecordPath.size());
+    for (auto Elem : RecordPath)
+      AddDeclRef(Elem);
+    return;
+  }
+  case APValue::LValue: {
+    push_back(Value.hasLValuePath() | Value.isLValueOnePastTheEnd() << 1 |
+              Value.getLValueBase().is<const Expr *>() << 2 |
+              Value.getLValueBase().is<TypeInfoLValue>() << 3 |
+              Value.isNullPointer() << 4 |
+              static_cast<bool>(Value.getLValueBase()) << 5);
+    QualType ElemTy;
+    if (Value.getLValueBase()) {
+      assert(!Value.getLValueBase().is<DynamicAllocLValue>() &&
+             "in C++20 dynamic allocation are transient so they shouldn't "
+             "appear in the AST");
+      if (!Value.getLValueBase().is<TypeInfoLValue>()) {
+        push_back(Value.getLValueBase().getCallIndex());
+        push_back(Value.getLValueBase().getVersion());
+        if (const auto *E = Value.getLValueBase().dyn_cast<const Expr *>()) {
+          AddStmt(const_cast<Expr *>(E));
+          ElemTy = E->getType();
+        } else {
+          AddDeclRef(Value.getLValueBase().get<const ValueDecl *>());
+          ElemTy = Value.getLValueBase().get<const ValueDecl *>()->getType();
+        }
+      } else {
+        AddTypeRef(
+            QualType(Value.getLValueBase().get<TypeInfoLValue>().getType(), 0));
+        AddTypeRef(Value.getLValueBase().getTypeInfoType());
+        ElemTy = Value.getLValueBase().getTypeInfoType();
+      }
+    }
+    push_back(Value.getLValueOffset().getQuantity());
+    push_back(Value.getLValuePath().size());
+    if (Value.hasLValuePath()) {
+      ArrayRef<APValue::LValuePathEntry> Path = Value.getLValuePath();
+      for (auto Elem : Path) {
+        if (ElemTy->getAs<RecordType>()) {
+          push_back(Elem.getAsBaseOrMember().getInt());
+          const Decl *BaseOrMember = Elem.getAsBaseOrMember().getPointer();
+          if (const auto *RD = dyn_cast<CXXRecordDecl>(BaseOrMember)) {
+            AddDeclRef(RD);
+            ElemTy = Writer->Context->getRecordType(RD);
+          } else {
+            const auto *VD = cast<ValueDecl>(BaseOrMember);
+            AddDeclRef(VD);
+            ElemTy = VD->getType();
+          }
+        } else {
+          push_back(Elem.getAsArrayIndex());
+          ElemTy = Writer->Context->getAsArrayType(ElemTy)->getElementType();
+        }
+      }
+    }
+  }
     return;
   }
   llvm_unreachable("Invalid APValue::ValueKind");
 }
 
 void ASTWriter::AddIdentifierRef(const IdentifierInfo *II, RecordDataImpl &Record) {
   Record.push_back(getIdentifierRef(II));
 }
 
 IdentID ASTWriter::getIdentifierRef(const IdentifierInfo *II) {
   if (!II)
     return 0;
 
   IdentID &ID = IdentifierIDs[II];

clang/test/ASTMerge/APValue/APValue.cpp

+// RUN: %clang_cc1 -std=gnu++2a -emit-pch %s -o %t.pch
+// RUN: %clang_cc1 -std=gnu++2a %s -DEMIT -ast-merge %t.pch -ast-dump-all | FileCheck %s
+
+// XFAIL: *
+
+#ifndef EMIT
+#define EMIT
+
+namespace Integer {
+
+consteval int fint() {
+  return 6789;
+}
+
+int Unique_Int = fint();
+//CHECK:      VarDecl {{.*}} Unique_Int
+//CHECK-NEXT: ConstantExpr {{.*}} 'int'
+//CHECK-NEXT: value: Int 6789
+
+consteval __uint128_t fint128() {
+  return ((__uint128_t)0x75f17d6b3588f843 << 64) | 0xb13dea7c9c324e51;
+}
+
+constexpr __uint128_t Unique_Int128 = fint128();
+//CHECK:      VarDecl {{.*}} Unique_Int128
+//CHECK-NEXT: value: Int 156773562844924187900898496343692168785
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: Int 156773562844924187900898496343692168785
+
+} // namespace Integer
+
+namespace FloatingPoint {
+
+consteval double fdouble() {
+  return double(567890.67890);
+}
+
+double Unique_Double = fdouble();
+//CHECK:      VarDecl {{.*}} Unique_Double
+//CHECK-NEXT: ConstantExpr {{.*}}
+//CHECK-NEXT: value: Float 5.678907e+05
+
+} // namespace FloatingPoint
+
+// FIXME: Add test for FixedPoint, ComplexInt, ComplexFloat, AddrLabelDiff.
+
+namespace Struct {
+
+struct B {
+  int i;
+  double d;
+};
+
+consteval B fB() {
+  return B{1, 0.7};
+}
+
+constexpr B Basic_Struct = fB();
+//CHECK:      VarDecl {{.*}} Basic_Struct
+//CHECK-NEXT: value: Struct
+//CHECK-NEXT: fields: Int 1, Float 7.000000e-01
+//CHECK-NEXT: ImplicitCastExpr
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: Struct
+//CHECK-NEXT: fields: Int 1, Float 7.000000e-01
+
+struct C {
+  int i = 9;
+};
+
+struct A : B {
+  constexpr A(B b, int I, double D, C _c) : B(b), i(I), d(D), c(_c) {}
+  int i;
+  double d;
+  C c;
+};
+
+consteval A fA() {
+  return A(Basic_Struct, 1, 79.789, {});
+}
+
+A Advanced_Struct = fA();
+//CHECK:      VarDecl {{.*}} Advanced_Struct
+//CHECK-NEXT: ConstantExpr {{.*}}
+//CHECK-NEXT: value: Struct
+//CHECK-NEXT: base: Struct
+//CHECK-NEXT: fields: Int 1, Float 7.000000e-01
+//CHECK-NEXT: fields: Int 1, Float 7.978900e+01
+//CHECK-NEXT: field: Struct
+//CHECK-NEXT: field: Int 9
+
+} // namespace Struct
+
+namespace Vector {
+
+using v4si = int __attribute__((__vector_size__(16)));
+
+consteval v4si fv4si() {
+  return (v4si){8, 2, 3};
+}
+
+v4si Vector_Int = fv4si();
+//CHECK:      VarDecl {{.*}} Vector_Int
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: Vector length=4
+//CHECK-NEXT: elements: Int 8, Int 2, Int 3, Int 0
+
+} // namespace Vector
+
+namespace Array {
+
+struct B {
+  int arr[6];
+};
+
+consteval B fint() {
+  return B{1, 2, 3, 4, 5, 6};
+}
+
+B Array_Int = fint();
+//CHECK:      VarDecl {{.*}} Array_Int
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: Struct
+//CHECK-NEXT: field: Array size=6
+//CHECK-NEXT: elements: Int 1, Int 2, Int 3, Int 4
+//CHECK-NEXT: elements: Int 5, Int 6
+
+struct A {
+  int i = 789;
+  double d = 67890.09876;
+};
+
+struct C {
+  A arr[3];
+};
+
+consteval C fA() {
+  return {{A{}, A{-45678, 9.8}, A{9}}};
+}
+
+C Array2_Struct = fA();
+//CHECK:      VarDecl {{.*}} Array2_Struct
+//CHECK-NEXT: ConstantExpr {{.*}}
+
+using v4si = int __attribute__((__vector_size__(16)));
+
+struct D {
+  v4si arr[2];
+};
+
+consteval D fv4si() {
+  return {{{1, 2, 3, 4}, {4, 5, 6, 7}}};
+}
+
+D Array_Vector = fv4si();
+//CHECK:      VarDecl {{.*}} Array_Vector
+//CHECK-NEXT: ConstantExpr {{.*}}
+//CHECK-NEXT: value: Struct
+//CHECK-NEXT: field: Array size=2
+//CHECK-NEXT: element: Vector length=4
+//CHECK-NEXT: elements: Int 1, Int 2, Int 3, Int 4
+//CHECK-NEXT: element: Vector length=4
+//CHECK-NEXT: elements: Int 4, Int 5, Int 6, Int 7
+
+} // namespace Array
+
+namespace Union {
+
+struct A {
+  int i = 6789;
+  float f = 987.9876;
+};
+
+union U {
+  int i;
+  A a{567890, 9876.5678f};
+};
+
+consteval U fU1() {
+  return U{0};
+}
+
+U Unique_Union1 = fU1();
+//CHECK:      VarDecl {{.*}} Unique_Union
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: Union .i Int 0
+
+consteval U fU() {
+  return U{};
+}
+
+U Unique_Union2 = fU();
+//CHECK:      VarDecl {{.*}} Unique_Union
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: Union .a
+//CHECK-NEXT: Struct
+//CHECK-NEXT: fields: Int 567890, Float 9.876567e+03
+
+} // namespace Union
+
+namespace MemberPointer {
+
+struct A {
+  struct B {
+    struct C {
+      struct D {
+        struct E {
+          struct F {
+            struct G {
+              int i;
+            };
+          };
+        };
+      };
+    };
+  };
+};
+
+consteval auto fmem_ptr() -> decltype(&A::B::C::D::E::F::G::i) {
+  return &A::B::C::D::E::F::G::i;
+}
+
+auto MemberPointer1 = fmem_ptr();
+//CHECK:      VarDecl {{.*}} MemberPointer1
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: MemberPointer &G::i
+
+struct A1 {
+  struct B1 {
+    int f() const {
+      return 0;
+    }
+  };
+};
+
+consteval auto fmem_ptr2() {
+  return &A1::B1::f;
+}
+
+auto MemberPointer2 = fmem_ptr2();
+//CHECK:      VarDecl {{.*}} MemberPointer2
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: MemberPointer &B1::f
+
+} // namespace MemberPointer
+
+namespace std {
+struct type_info;
+};
+
+namespace LValue {
+
+constexpr int g = 0;
+
+consteval const int &fg_ref() {
+  return g;
+}
+
+const int &g_ref = fg_ref();
+//CHECK:      VarDecl {{.*}} g_ref
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue &g
+
+consteval const int *fint_ptr() {
+  return &g;
+}
+
+const int *g_ptr = fint_ptr();
+//CHECK:      VarDecl {{.*}} g_ptr
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue &g
+
+consteval const int *fnull_ptr() {
+  return nullptr;
+}
+
+const int *ptr2 = fnull_ptr();
+//CHECK:      VarDecl {{.*}} ptr2
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue nullptr
+
+int fconst();
+
+consteval auto ffunc_ptr() {
+  return &fconst;
+}
+
+int (*func_ptr)() = ffunc_ptr();
+//CHECK:      VarDecl {{.*}} func_ptr
+//CHECK-NEXT: ConstantExpr {{.*}}
+//CHECK-NEXT: value: LValue &fconst
+
+struct A {
+  int Arr[6] = {0, 1, 3, 4, 5, 9};
+  int i = 0;
+};
+
+struct D {
+  A arr[6] = {};
+};
+
+consteval D fA() {
+  return {};
+}
+
+constexpr D Arr = fA();
+// CHECK:      VarDecl {{.*}} Arr
+// CHECK-NEXT: value: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: ImplicitCastExpr
+// CHECK-NEXT: ConstantExpr
+// CHECK-NEXT: value: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+// CHECK-NEXT: element: Struct
+// CHECK-NEXT: field: Array size=6
+// CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+// CHECK-NEXT: elements: Int 5, Int 9
+// CHECK-NEXT: field: Int 0
+
+consteval const int &fconstintref() {
+  return Arr.arr[0].i;
+}
+
+const int &ArrayStructRef1 = fconstintref();
+//CHECK:      VarDecl {{.*}} ArrayStructRef1
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue &Arr.arr[0].i
+
+consteval const int &fconstintref2() {
+  return Arr.arr[1].Arr[5];
+}
+
+const int &ArrayStructRef2 = fconstintref2();
+//CHECK:      VarDecl {{.*}} ArrayStructRef2
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue &Arr.arr[1].Arr[5]
+
+consteval const int *fconststar() {
+  return &ArrayStructRef2;
+}
+
+const int *ArrayStructRef3 = fconststar();
+//CHECK:      VarDecl {{.*}} ArrayStructRef3
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue  &Arr.arr[1].Arr[5]
+
+struct B : A {
+};
+
+struct C {
+  B b;
+};
+
+consteval C fC() {
+  return {};
+}
+
+C c = fC();
+//CHECK:      VarDecl {{.*}} c
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: Struct
+//CHECK-NEXT: field: Struct
+//CHECK-NEXT: base: Struct
+//CHECK-NEXT: field: Array size=6
+//CHECK-NEXT: elements: Int 0, Int 1, Int 3, Int 4
+//CHECK-NEXT: elements: Int 5, Int 9
+//CHECK-NEXT: field: Int 0
+
+consteval const int &f2constintref() {
+  return c.b.i;
+}
+
+const int &StructPathRef = f2constintref();
+//CHECK:      VarDecl {{.*}} StructPathRef
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue &c.b.A::i
+
+consteval const std::type_info *ftype_info() {
+  return &typeid(c);
+}
+
+const std::type_info *T1 = ftype_info();
+//CHECK:      VarDecl {{.*}} T1
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT:value: LValue &typeid(LValue::C)
+
+consteval const std::type_info *ftype_info2() {
+  return &typeid(Arr.arr[1].Arr[2]);
+}
+
+const std::type_info *T2 = ftype_info2();
+//CHECK:      VarDecl {{.*}} T2
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue &typeid(int)
+
+consteval const char *fstring() {
+  return "test";
+}
+
+const char *cptr = fstring();
+//CHECK:      VarDecl {{.*}} cptr
+//CHECK-NEXT: ConstantExpr
+//CHECK-NEXT: value: LValue &"test"[0]
+
+} // namespace LValue
+
+#endif