[clang][WebAssembly] Implement support for table types and builtins

[pmatos]

Summary

This commit implements support for WebAssembly table types and
respective builtins. Table tables are WebAssembly objects to store
reference types. They have a large amount of semantic restrictions
including, but not limited to, only being allowed to be declared
at the top-level as static arrays of zero-length. Not being arguments
or result of functions, not being stored ot memory, etc.

This commit introduces the attribute((wasm_table)) to attach to
arrays of WebAssembly reference types. And the following builtins to
manage tables:

• ref __builtin_wasm_table_get(table, idx)
• void __builtin_wasm_table_set(table, idx, ref)
• uint __builtin_wasm_table_size(table)
• uint __builtin_wasm_table_grow(table, ref, uint)
• void __builtin_wasm_table_fill(table, idx, ref, uint)
• void __builtin_wasm_table_copy(table, table, uint, uint, uint)

This commit also enables reference-types feature at bleeding-edge.

This is joint work with Alex Bradbury (@asb).

[aaron.ballman]

clang/include/clang/Basic/DiagnosticSemaKinds.td

11758

This is untested. I'll stop commenting on those at this point, please ensure you're testing all diagnostics you've added.

clang/lib/AST/Type.cpp

2333–2338

[pmatos]

Updating tests after some changes to previous diagnostics.

[pmatos]

clang/include/clang/Basic/DiagnosticSemaKinds.td

2171–2177

Right - this is no longer needed.

3035–3041

Sigh - again. Apologies. This was an initial patch that used matrix subscript to create a table subscript patch but was dropped and therefore is unused.

[pmatos]

Remove some unnecessary diagnostics.

[pmatos]

clang/include/clang/Basic/DiagnosticSemaKinds.td

11761

Yes, the next phase of this work is to implement this together with element section to initialize tables.

[asb]

clang/include/clang/Basic/DiagnosticSemaKinds.td

11791

The whack-a-mole aspect of disallowing table uses is something I'm not fond of either....but I'm not sure I see a better approach. Do you have any alternatives in mind?

[pmatos]

Address more comments.

[pmatos]

Fix some tests whose diagnostics changed

[pmatos]

Finish fixing tests after dianostic message changes

[pmatos]

Further tests for use of tables in conditional branches.

[pmatos]

Simplify and add tests for remaining diagnostics

[pmatos]

clang/include/clang/Basic/DiagnosticSemaKinds.td

11791

A couple concrete answers in addition to what @asb already said.

• I don't think we can use tables at the moment in conditional explicit clause. Indeed it doesn't make sense since there's no what, at the moment, to statically initialize the table.
• Tables are thread local. Indeed, threads in WebAssembly share only linear memory so anything that's not in linear memory is thread local. This is true for tables but also for all reference types.

[pmatos]

Add missing newline at end of file.

[pmatos]

@aaron.ballman Thanks for all the comments, I have now finished addressing those. What do you think of the current patch?

[pmatos]

Rebase on main and fix a test diagnostic expectation.

[pmatos]

Rebased on current HEAD.

[aaron.ballman]

clang/include/clang/AST/Stmt.h

455

I am not certain what AMT stands for -- you might need some comments to explain what this stands for.

clang/include/clang/Basic/DiagnosticSemaKinds.td

11791

The whack-a-mole aspect of disallowing table uses is something I'm not fond of either....but I'm not sure I see a better approach. Do you have any alternatives in mind?

I don't have good ideas off the top of my head, but this is a lot of overhead for the feature so my default idea is "don't add this type to the compiler" which may not help all that much. Do you have evidence that this type is necessary, will have enough uses in the wild to justify adding it, and is not possible to make it more regular?

[pmatos]

Address the comments.

[pmatos]

clang/include/clang/AST/Stmt.h

455

Ah yes, somehow I missed this. I renamed this at some point with an application in mind and then didn't use it. So renamed back.

AMT was supposed to be Array / Matrix / Table.

clang/include/clang/Basic/DiagnosticSemaKinds.td

11791

The whack-a-mole aspect of disallowing table uses is something I'm not fond of either....but I'm not sure I see a better approach. Do you have any alternatives in mind?

I don't have good ideas off the top of my head, but this is a lot of overhead for the feature so my default idea is "don't add this type to the compiler" which may not help all that much. Do you have evidence that this type is necessary, will have enough uses in the wild to justify adding it, and is not possible to make it more regular?

A table is a container for reference types - i.e. externref, funcref and others in the future and an essential part of WebAssembly. I don't see how we can compile down to tables unless we enforce these constraints at this level. I wish there was a way of providing the same functionality without needing to add all these extra checks (and would welcome alternate suggestions!), but this is the only path forwards we've been able to find..

[aaron.ballman]

Roping in @jfb because I know he's been heavily involve in WebAssembly in the past and he may have ideas/opinions.

High-level question: are externref, funcref, and table types all part of the WebAssembly standard, or are these extensions? (I wasn't aware that WebAssembly was a W3C standard or I'd have been asking this question much earlier -- sorry for that! I'm asking in regards to #4 in https://clang.llvm.org/get_involved.html#criteria)

[pmatos]

Address comments regarding tables and remove some unused code.

[tlively]

In D139010#4158540, @aaron.ballman wrote:

Roping in @jfb because I know he's been heavily involve in WebAssembly in the past and he may have ideas/opinions.

High-level question: are externref, funcref, and table types all part of the WebAssembly standard, or are these extensions? (I wasn't aware that WebAssembly was a W3C standard or I'd have been asking this question much earlier -- sorry for that! I'm asking in regards to #4 in https://clang.llvm.org/get_involved.html#criteria)

Yes, these features are all present in the WebAssembly standard: https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/syntax/types.html#table-types

[aaron.ballman]

In D139010#4159307, @tlively wrote:

In D139010#4158540, @aaron.ballman wrote:

Roping in @jfb because I know he's been heavily involve in WebAssembly in the past and he may have ideas/opinions.

High-level question: are externref, funcref, and table types all part of the WebAssembly standard, or are these extensions? (I wasn't aware that WebAssembly was a W3C standard or I'd have been asking this question much earlier -- sorry for that! I'm asking in regards to #4 in https://clang.llvm.org/get_involved.html#criteria)

Yes, these features are all present in the WebAssembly standard: https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/syntax/types.html#table-types

Thank you, that resolves any concerns I had about whether this met our usual extension criteria. I'm still uncomfortable with the type though because... it doesn't behave like anything else in the type system. I asked some questions on the test cases, and maybe knowing those answers will help me wrap my head around the design of the type.

clang/test/SemaCXX/wasm-refs-and-tables.cpp

17–18

This seems really... confused. We can't form a pointer to the type, but we can form an array of the type (which decays into a pointer when you sneeze near it, and it's not clear whether that should be allowed or not) so long as it's a zero-length array (which is an extension in C and C++, so do we need to silence pedantic warnings in WASM for this?).

89

96

103

This involves array to pointer decay, so we're forming a pointer to the table here. Why is this pointer fine but others are not?

[pmatos]

Rebase on main.

[pmatos]

Remove references to table subscript. Simplify patch.

[pmatos]

Address concerns about table subscripting. Add warnings for that.

Address a few other smaller comments like testing for table comparisons.

clang/test/SemaCXX/wasm-refs-and-tables.cpp

17–18

As it stands, tables are declared as static arrays of size zero. Then to access them we need to use builtins. No subscripting, no comparison, no pointer decay, etc. No passing into functions, returning from functions, etc. Nothing besides using them as arguments to wasm_table... builtins.

89

No comparisons are allowed - I have added a few tests to that effect.

96

(void)table; is allowed.

103

I have disallowed this to avoid the problems you mention. Table set happens only through the builtin wasm_table_set.

[pmatos]

@aaron.ballman Any further comments on this?

[aaron.ballman]

This will also need someone from the LLVM side to look at the LLVM-specific changes. Most of my comments were focused on the behavior of test cases, but there may be more comments coming for the code changes once I've got a better handle on the test behavior.

clang/include/clang/Basic/BuiltinsWebAssembly.def

205–210

All of these should be documented in docs/LanguageExtensions.rst (you can make a Web Assembly section if one doesn't already exist; we've historically been bad about documenting our builtins).

clang/test/Sema/builtins-wasm.c

13–14

Instead of relying on assignment diagnostics to test the return type of the call, why not use the language? (Same can be used for the other, similar tests.)

#define EXPR_HAS_TYPE(expr, type) _Generic((expr), type : 1, default : 0)

_Static_assert(EXPR_HAS_TYPE(__builtin_wasm_table_size(table), int), "");

22

I can't make sense of this diagnostic -- what is the element type of the web assembly table in the 1st argument? Why is the second argument needed at all if it needs to be derived from the type of the first argument and these things don't represent values (due to being zero-sized)?

33

Similar question here about the third argument.

clang/test/Sema/wasm-refs-and-tables.c

17

So why is extern __externref_t r2; allowed? Is it because it's not an array declaration?

21–23

For completeness (should just work)

48

How about:

void foo(__externref_t table[0]);

I'd expect this to also not be allowed (that's just a fancy spelling for a weird pointer).

81

Shouldn't this be in builtins-wasm.c instead?

83–84

This needs some further test cases for situations where the declaration isn't at the top level of the function. e.g.,

void foo() {
  static __externref_t t[0]; // error
  {
    static __externref_t t2[0]; // error
    for (;;) {
      static __externref_t t3[0]; // error
    }
  }
  int i = ({ static __externref_t t4[0]; /* error, I presume? */ 1;});
}

and also a C++ test involving lambdas (we should probably also cover blocks in C, I suppose).

104

Please don't hate me, but... what about:

int i = 0;
__externref_t oh_no_vlas[i];

clang/test/SemaCXX/wasm-refs-and-tables.cpp

7–8

Much of this file is the same test coverage as in the C case; I'd recommend combining the .c and .cpp files into one test with two RUN lines, and use -verify=whatever to distinguish between C vs C++ vs both diagnostic behaviors. The C++ specific code can then be split into a much smaller .cpp-specific file.

15

Anywhere you'd testing pointer behavior for C++, you should have a test with an lvalue reference as well. I presume those will behave the same as pointers? It'd probably be wise to have tests for rvalue references as well.

17–18

Okay, that's less confused now, thank you! What should the -pedantic behavior be for this:

static __externref_t table[0];

I presume you don't want the usual "zero size arrays are an extension" warning?

119

We should probably have a test for co_return behavior as well?

[pmatos]

clang/test/Sema/builtins-wasm.c

13–14

OK - I will apply those changes. I hadn't seen this way of doing this before. Thanks.

22

The element type needs to be a reference type. Either an externref or a funcref. So, if we have a table of externref, the second element needs to have that type because it's the element we are growing the table with. The element is needed because it's what we'll use to fill the table with.

Well... they do represent values, just not values that exist on webassembly module. They are host values. They are for example javascript strings, or numbers, or objects of any kind. They are just opaque in the webassembly module but if retrieved by the javascript side they are just normal sized objects.

33

Exactly the same story as above.

[pmatos]

Fix Wasm table tests.

[pmatos]

Thanks for the comments - I am working on addressing these at the moment.
The LLVM part of the patch is just some refactoring and therefore should be pretty trivial, pinging @tlively in case he has some time.

clang/test/Sema/wasm-refs-and-tables.c

17

I am not sure I understand the question. The externref value can be declared in another module and here we just define that. Array declarations of externref just define tables of externref values.

48

That's correct, that's not allowed. Added the test case.

104

:) Test added.

[pmatos]

Complete fixing tests.

[aaron.ballman]

clang/test/Sema/wasm-refs-and-tables.c

17

Thanks, that helps explain my confusion (boy, I *really* do not like these types; they are quite unintuitive). What was confusing me here is that __externref_t t7[0]; fails because the declaration doesn't declare a static identifier (yet, in C, it doesn't declare *anything at all* because it an array of zero elements of a sizeless type) while extern __externref_t r2; is fine despite not declaring a static identifier (yet, in C, it also doesn't declare *anything at all* because it's a sizeless type). I don't think there's anything to be done about this, the design is what it is in the WebAssembly standard, but all of my discomfort stems around how deeply weird this design is (and it shows with just how much effort we have to go to in order to restrict all the various ways you can use these identifiers).

[pmatos]

clang/include/clang/Basic/BuiltinsWebAssembly.def

205–210

Working on this - thanks for the reminder.

clang/test/SemaCXX/wasm-refs-and-tables.cpp

7–8

I have don't this know. I was not aware we could pass an argument to verify - thanks.

15

Here I guess you're talking about testing __externref_t &. However, this might be outside the scope of the patch which deals only with tables.

I could add further lvalue and rvalue reference tests to externref and funcref in another patch. What do you think?

17–18

I have fixed this but unsure how to best merge it with the remainder of the tests, so created a new test file.

[pmatos]

Update a few more tests.

[pmatos]

clang/test/Sema/wasm-refs-and-tables.c

17

Yes, I understand.

[pmatos]

Quick fixup of test.

[pmatos]

clang/test/SemaCXX/wasm-refs-and-tables.cpp

36

@aaron.ballman I tried and failed to create a good testcase for co_return. However creating coroutines seems to be an stdlib thing which I am not sure how to test here. Do you have any suggestions here?

[pmatos]

Add documentation for table builtins.

[pmatos]

I think we are almost there. @aaron.ballman what do you think?

clang/test/Sema/wasm-refs-and-tables.c

81

Moved.

[pmatos]

@tlively @aaron.ballman pinging both to get final reviews on the LLVM and Clang parts respectively. It would be great to have this merged soon.

[tlively]

Thanks for the ping, will take a look.

[tlively]

It looks like the LLVM-side changes are generally moving Wasm type classification functions to a more global location. Since no other backend should care about these things, it would be better if we could get away without these changes.

llvm/include/llvm/IR/Type.h

23

I don't know if things in IR are supposed to depend on things in CodeGen. Is there precedent here?

199–211

Do these need to be in Type.h? If not, it would be good to keep them in a more Wasm-specific location.

[pmatos]

Remove modifications from Type.h and move them to WebAssembly files.

[pmatos]

In D139010#4350869, @tlively wrote:

It looks like the LLVM-side changes are generally moving Wasm type classification functions to a more global location. Since no other backend should care about these things, it would be better if we could get away without these changes.

@tlively Fortunately, this is not needed anymore. Thanks for pointing it out. At some point it was due to dependencies from Clang code which used the predicates from LLVM and we couldn't include the WebAssembly backend there so it was easier to have them in llvm Type.h. But that code was refactored and I could move the LLVM predicates back to the backend files. How does it look like now?

[aaron.ballman]

clang/docs/LanguageExtensions.rst

2288 ↗

(On Diff #523741)

This sounds like any reference type will work, e.g.,

static __externref_t table[0];
void func(int i) {
  int &ref = i;
  __builtin_wasm_table_set(table, i, ref);
}

so might want to say "value of `_externref_t` type" instead?

2291–2292 ↗

(On Diff #523741)

Sphinx will bark otherwise.

2303 ↗

(On Diff #523741)

2309–2310 ↗

(On Diff #523741)

Sphinx will bark otherwise.

2321 ↗

(On Diff #523741)

Returns an int? size_t? Something else?

2324–2325 ↗

(On Diff #523741)

2340 ↗

(On Diff #523741)

Same suggestion here as above regarding arbitrary reference types.

2345–2346 ↗

(On Diff #523741)

2360–2361 ↗

(On Diff #523741)

Same suggestion here as above regarding arbitrary reference types.

2364–2365 ↗

(On Diff #523741)

What happens if the range is invalid for the table size? e.g., the user never called __builtin_wasm_table_grow before calling __builtin_wasm_table_fill?

2367–2368 ↗

(On Diff #523741)

2385 ↗

(On Diff #523741)

Similar question here as above -- what happens when the range given is invalid for either one or both of the table arguments?

clang/test/SemaCXX/wasm-refs-and-tables.cpp

36

#include "Inputs/std-coroutine.h"

using std::suspend_always;

struct promise_table {
  __externref_t[] get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend() noexcept;
  void return_value(__externref_t[]);
  void unhandled_exception();
};

template <typename... T>
struct std::coroutine_traits<__externref_t[], T...> { using promise_type = promise_table; };

static __externref_t table[0];
__externref_t[] func() {
  co_return table; // Cannot return a WebAssembly table?
}

Perhaps something along these lines?

llvm/include/llvm/CodeGen/WasmAddressSpaces.h

44

Still need to add this newline back, btw.

[pmatos]

Address remaining comments.

Make table.size builtin return size_t.
Still remaining to be address is co_return on tables.

[pmatos]

clang/docs/LanguageExtensions.rst

2288 ↗

(On Diff #523741)

Any reference type will work, i.e. externref or funcref. You can also store funcrefs in a wasm table. But of course, it needs to be well-typed. You cannot store a funcref value in an externref table and vice-versa.

2321 ↗

(On Diff #523741)

Good point, should actually be size_t. Will change that and clarify in the documentation.

2340 ↗

(On Diff #523741)

Same situation as above. These builtins can get any reference type, as long as they match the table element type.

2360–2361 ↗

(On Diff #523741)

Same as above.

2364–2365 ↗

(On Diff #523741)

The host executing the WebAssembly instance will trap. This is part of the WebAssembly spec.

2385 ↗

(On Diff #523741)

Trap on the host.

clang/test/SemaCXX/wasm-refs-and-tables.cpp

36

But you cannot write promise_table because a table cannot be an argument in return_value. Also, you cannot return a table in get_return_object. Doesn't this invalidate straight away the use of a table with co-routines?

[aaron.ballman]

clang/docs/LanguageExtensions.rst

2288 ↗

(On Diff #523741)

My point is more that "any reference type" suggests you can use an arbitrary C++ reference type like int & and I think we mean something more specific than that, right?

2364–2365 ↗

(On Diff #523741)

Hmmm, do you think we should mention that here? Alternatively, should we have a link to other WebAssembly documentation so we can say "see <blah> for more details?" to avoid replicating docs too much?

clang/test/SemaCXX/wasm-refs-and-tables.cpp

36

Ah! Yeah, I think that does. Okay, let's punt on coroutines, that's turning out to be a slog.

[pmatos]

clang/docs/LanguageExtensions.rst

2288 ↗

(On Diff #523741)

Yes, of course, I always mean a WebAssembly reference type in this context.

2364–2365 ↗

(On Diff #523741)

Good idea. I will handle that.

clang/test/SemaCXX/wasm-refs-and-tables.cpp

36

OK - thanks.

[pmatos]

Address the comments wrt the documentation. Added link to Wasm spec.

@aaron.ballman What do you think? I added the reference to the top level of the WebAssembly section, rather than to the documentation in each builtin since it makes more sense imo.

[pmatos]

Remove test portion attempting to test coroutines.

[pmatos]

Apply clang-format.

[aaron.ballman]

Spotted a typo in the docs, but otherwise LGTM (thanks for your patience while I was out last week).

clang/docs/LanguageExtensions.rst

2310 ↗

(On Diff #526578)

2288 ↗

(On Diff #523741)

Thanks for the clarifying note!

[pmatos]

In D139010#4400303, @aaron.ballman wrote:

Spotted a typo in the docs, but otherwise LGTM (thanks for your patience while I was out last week).

Thanks for your time one this.

clang/include/clang/AST/ASTContext.h

public:
   /// vector of the specified element type.
   ///
   /// FIXME: We will need these to be uniqued, or at least comparable, at some
   /// point.
   QualType getDependentSizedExtVectorType(QualType VectorType,
                                           Expr *SizeExpr,
                                           SourceLocation AttrLoc) const;
 
+  /// Return the unique reference to the Wasm table type of the specified 
+  /// element type
+  QualType getWasmTableType(QualType EltTy) const;
+
   /// Return the unique reference to the matrix type of the specified element
   /// type and size
   ///
   /// \pre \p ElementType must be a valid matrix element type (see
   /// MatrixType::isValidElementType).
   QualType getConstantMatrixType(QualType ElementType, unsigned NumRows,
                                  unsigned NumColumns) const;
 

clang/include/clang/AST/Expr.h

class ArraySubscriptExpr : public Expr {
   bool lhsIsBase() const { return getRHS()->getType()->isIntegerType(); }
 
 public:
   ArraySubscriptExpr(Expr *lhs, Expr *rhs, QualType t, ExprValueKind VK,
                      ExprObjectKind OK, SourceLocation rbracketloc)
       : Expr(ArraySubscriptExprClass, t, VK, OK) {
     SubExprs[LHS] = lhs;
     SubExprs[RHS] = rhs;
-    ArrayOrMatrixSubscriptExprBits.RBracketLoc = rbracketloc;
+    AMTSubscriptExprBits.RBracketLoc = rbracketloc;
     setDependence(computeDependence(this));
   }
 
   /// Create an empty array subscript expression.
   explicit ArraySubscriptExpr(EmptyShell Shell)
     : Expr(ArraySubscriptExprClass, Shell) { }
 
   /// An array access can be written A[4] or 4[A] (both are equivalent).
public:
   const Expr *getIdx() const { return lhsIsBase() ? getRHS() : getLHS(); }
 
   SourceLocation getBeginLoc() const LLVM_READONLY {
     return getLHS()->getBeginLoc();
   }
   SourceLocation getEndLoc() const { return getRBracketLoc(); }
 
   SourceLocation getRBracketLoc() const {
-    return ArrayOrMatrixSubscriptExprBits.RBracketLoc;
+    return AMTSubscriptExprBits.RBracketLoc;
   }
   void setRBracketLoc(SourceLocation L) {
-    ArrayOrMatrixSubscriptExprBits.RBracketLoc = L;
+    AMTSubscriptExprBits.RBracketLoc = L;
   }
 
   SourceLocation getExprLoc() const LLVM_READONLY {
     return getBase()->getExprLoc();
   }
 
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == ArraySubscriptExprClass;

 public:
   MatrixSubscriptExpr(Expr *Base, Expr *RowIdx, Expr *ColumnIdx, QualType T,
                       SourceLocation RBracketLoc)
       : Expr(MatrixSubscriptExprClass, T, Base->getValueKind(),
              OK_MatrixComponent) {
     SubExprs[BASE] = Base;
     SubExprs[ROW_IDX] = RowIdx;
     SubExprs[COLUMN_IDX] = ColumnIdx;
-    ArrayOrMatrixSubscriptExprBits.RBracketLoc = RBracketLoc;
+    AMTSubscriptExprBits.RBracketLoc = RBracketLoc;
     setDependence(computeDependence(this));
   }
 
   /// Create an empty matrix subscript expression.
   explicit MatrixSubscriptExpr(EmptyShell Shell)
       : Expr(MatrixSubscriptExprClass, Shell) {}
 
   bool isIncomplete() const {
public:
 
   SourceLocation getEndLoc() const { return getRBracketLoc(); }
 
   SourceLocation getExprLoc() const LLVM_READONLY {
     return getBase()->getExprLoc();
   }
 
   SourceLocation getRBracketLoc() const {
-    return ArrayOrMatrixSubscriptExprBits.RBracketLoc;
+    return AMTSubscriptExprBits.RBracketLoc;
   }
   void setRBracketLoc(SourceLocation L) {
-    ArrayOrMatrixSubscriptExprBits.RBracketLoc = L;
+    AMTSubscriptExprBits.RBracketLoc = L;
   }
 
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == MatrixSubscriptExprClass;
   }
 
   // Iterators
   child_range children() {

clang/include/clang/AST/Stmt.h

class UnaryExprOrTypeTraitExprBitfields {
     friend class UnaryExprOrTypeTraitExpr;
 
     unsigned : NumExprBits;
 
     unsigned Kind : 3;
     unsigned IsType : 1; // true if operand is a type, false if an expression.
   };
 
-  class ArrayOrMatrixSubscriptExprBitfields {
+  class AMTSubscriptExprBitfields {
     friend class ArraySubscriptExpr;
     friend class MatrixSubscriptExpr;
 
     unsigned : NumExprBits;
 
     SourceLocation RBracketLoc;
   };
 
union {
     ConstantExprBitfields ConstantExprBits;
     PredefinedExprBitfields PredefinedExprBits;
     DeclRefExprBitfields DeclRefExprBits;
     FloatingLiteralBitfields FloatingLiteralBits;
     StringLiteralBitfields StringLiteralBits;
     CharacterLiteralBitfields CharacterLiteralBits;
     UnaryOperatorBitfields UnaryOperatorBits;
     UnaryExprOrTypeTraitExprBitfields UnaryExprOrTypeTraitExprBits;
-    ArrayOrMatrixSubscriptExprBitfields ArrayOrMatrixSubscriptExprBits;
+    AMTSubscriptExprBitfields AMTSubscriptExprBits;
     CallExprBitfields CallExprBits;
     MemberExprBitfields MemberExprBits;
     CastExprBitfields CastExprBits;
     BinaryOperatorBitfields BinaryOperatorBits;
     InitListExprBitfields InitListExprBits;
     ParenListExprBitfields ParenListExprBits;
     GenericSelectionExprBitfields GenericSelectionExprBits;
     PseudoObjectExprBitfields PseudoObjectExprBits;

clang/include/clang/AST/Type.h

public:
   bool isTriviallyRelocatableType(const ASTContext &Context) const;
 
   /// Returns true if it is a class and it might be dynamic.
   bool mayBeDynamicClass() const;
 
   /// Returns true if it is not a class or if the class might not be dynamic.
   bool mayBeNotDynamicClass() const;
 
+  /// Returns true if it is a WebAssembly Reference Type.
+  bool isWebAssemblyReferenceType() const;
+
+  /// Returns true if it is a WebAssembly Externref Type.
+  bool isWebAssemblyExternrefType() const;
+
+  /// Returns true if it is a WebAssembly Funcref Type.
+  bool isWebAssemblyFuncrefType() const;
+
   // Don't promise in the API that anything besides 'const' can be
   // easily added.
 
   /// Add the `const` type qualifier to this QualType.
   void addConst() {
     addFastQualifiers(Qualifiers::Const);
   }
   QualType withConst() const {
public:
   /// every type is one or the other.  Standard types are all sized;
   /// sizeless types are purely an extension.
   ///
   /// Sizeless types contain data with no specified size, alignment,
   /// or layout.
   bool isSizelessType() const;
   bool isSizelessBuiltinType() const;
 
-  /// Check if this is a WebAssembly Reference Type.
-  bool isWebAssemblyReferenceType() const;
+  /// Check if this is a WebAssembly Externref Type.
   bool isWebAssemblyExternrefType() const;
 
+  /// Returns true if this is a WebAssembly table type: either an array of
+  /// reference types, or a pointer to a reference type (which can only be
+  /// created by array to pointer decay).
+  bool isWebAssemblyTableType() const;
+
   /// Determines if this is a sizeless type supported by the
   /// 'arm_sve_vector_bits' type attribute, which can be applied to a single
   /// SVE vector or predicate, excluding tuple types such as svint32x4_t.
   bool isVLSTBuiltinType() const;
 
   /// Returns the representative type for the element of an SVE builtin type.
   /// This is used to represent fixed-length SVE vectors created with the
   /// 'arm_sve_vector_bits' type attribute as VectorType.

clang/include/clang/Basic/Attr.td

def FunctionReturnThunks : InheritableAttr,
   let Documentation = [FunctionReturnThunksDocs];
 }
 
 def WebAssemblyFuncref : TypeAttr, TargetSpecificAttr<TargetWebAssembly> {
   let Spellings = [Keyword<"__funcref">];
   let Documentation = [WebAssemblyExportNameDocs];
   let Subjects = SubjectList<[TypedefName], ErrorDiag>;
 }
+
+def WasmTableType : TypeAttr {
+  let Spellings = [Clang<"wasm_table">];
+  let Subjects = SubjectList<[TypedefName], ErrorDiag>;
+  let Documentation = [Undocumented];
+  let ASTNode = 0;
+  let PragmaAttributeSupport = 0;
+}
 No newline at end of file

clang/include/clang/Basic/BuiltinsWebAssembly.def

 
 TARGET_BUILTIN(__builtin_wasm_ref_null_extern, "i", "nct", "reference-types")
 
 // A funcref represented as a function pointer with the funcref attribute
 // attached to the type, therefore SemaChecking will check for the right
 // return type.
 TARGET_BUILTIN(__builtin_wasm_ref_null_func, "i", "nct", "reference-types")
 
+// Table builtins
+TARGET_BUILTIN(__builtin_wasm_table_set,  "viii", "t", "reference-types")
+TARGET_BUILTIN(__builtin_wasm_table_get,  "iii", "t", "reference-types")
+TARGET_BUILTIN(__builtin_wasm_table_size, "ii", "nt", "reference-types")
+TARGET_BUILTIN(__builtin_wasm_table_grow, "iiii", "nt", "reference-types")
+TARGET_BUILTIN(__builtin_wasm_table_fill, "viiii", "t", "reference-types")
+TARGET_BUILTIN(__builtin_wasm_table_copy, "viiiii", "t", "reference-types")
+
 #undef BUILTIN
 #undef TARGET_BUILTIN

clang/include/clang/Basic/DiagnosticSemaKinds.td

def err_init_list_bad_dest_type : Error<
   "list">;
 def warn_cxx20_compat_aggregate_init_with_ctors : Warning<
   "aggregate initialization of type %0 with user-declared constructors "
   "is incompatible with C++20">, DefaultIgnore, InGroup<CXX20Compat>;
 
 def err_reference_bind_to_bitfield : Error<
   "%select{non-const|volatile}0 reference cannot bind to "
   "bit-field%select{| %1}2">;
 def err_reference_bind_to_vector_element : Error<
   "%select{non-const|volatile}0 reference cannot bind to vector element">;
 def err_reference_bind_to_matrix_element : Error<
   "%select{non-const|volatile}0 reference cannot bind to matrix element">;
+def err_reference_bind_to_table_element : Error<
+  "%select{non-const|volatile}0 reference cannot bind to table element">;
 def err_reference_var_requires_init : Error<
   "declaration of reference variable %0 requires an initializer">;
 def err_reference_without_init : Error<
   "reference to type %0 requires an initializer">;
 def note_value_initialization_here : Note<
   "in value-initialization of type %0 here">;
 def err_reference_has_multiple_inits : Error<
   "reference cannot be initialized with multiple values">;
 def err_init_non_aggr_init_list : Error<

 def err_attribute_parameter_types : Error<
   "%0 attribute parameter types do not match: parameter %1 of function %2 has type %3, "
   "but parameter %4 of function %5 has type %6">;
 
 def err_attribute_too_many_arguments : Error<
   "%0 attribute takes no more than %1 argument%s1">;
 def err_attribute_too_few_arguments : Error<
   "%0 attribute takes at least %1 argument%s1">;
 def err_attribute_invalid_vector_type : Error<"invalid vector element type %0">;
 def err_attribute_invalid_bitint_vector_type : Error<
   "'_BitInt' vector element width must be %select{a power of 2|"
   "at least as wide as 'CHAR_BIT'}0">;
 def err_attribute_invalid_matrix_type : Error<"invalid matrix element type %0">;
+def err_attribute_invalid_wasm_table_type : Error<"invalid table element type %0">;
 def err_attribute_bad_neon_vector_size : Error<
   "Neon vector size must be 64 or 128 bits">;
 def err_attribute_invalid_sve_type : Error<
   "%0 attribute applied to non-SVE type %1">;
 def err_attribute_bad_sve_vector_size : Error<
   "invalid SVE vector size '%0', must match value set by "
   "'-msve-vector-bits' ('%1')">;
 def err_attribute_arm_feature_sve_bits_unsupported : Error<
   "%0 is only supported when '-msve-vector-bits=<bits>' is specified with a "
def ext_standalone_specifier : ExtWarn<"'%0' is not permitted on a declaration "
   "of a type">, InGroup<MissingDeclarations>;
 def err_standalone_class_nested_name_specifier : Error<
   "forward declaration of %select{class|struct|interface|union|enum}0 cannot "
   "have a nested name specifier">;
 def err_typecheck_sclass_func : Error<"illegal storage class on function">;
 def err_static_block_func : Error<
   "function declared in block scope cannot have 'static' storage class">;
 def err_typecheck_address_of : Error<"address of %select{bit-field"
-  "|vector element|property expression|register variable|matrix element}0 requested">;
+  "|vector element|property expression|register variable|matrix element|table element}0 requested">;
 def ext_typecheck_addrof_void : Extension<
   "ISO C forbids taking the address of an expression of type 'void'">;
 def err_unqualified_pointer_member_function : Error<
   "must explicitly qualify name of member function when taking its address">;
 def err_invalid_form_pointer_member_function : Error<
   "cannot create a non-constant pointer to member function">;
 def err_address_of_function_with_pass_object_size_params: Error<
   "cannot take address of function %0 because parameter %1 has "

 def err_builtin_invalid_arg_type: Error <
   "%ordinal0 argument must be a "
   "%select{vector, integer or floating point type|matrix|"
   "pointer to a valid matrix element type|"
   "signed integer or floating point type|vector type|"
   "floating point type|"
   "vector of integers}1 (was %2)">;
 
+def err_wasm_table_disabled: Error<
+  "WebAssembly table support is disabled. Pass -mreference-types to enable it">;
 def err_builtin_matrix_disabled: Error<
   "matrix types extension is disabled. Pass -fenable-matrix to enable it">;
+def err_table_index_not_integer: Error<
+  "table index must be an integer">;
 def err_matrix_index_not_integer: Error<
   "matrix %select{row|column}0 index is not an integer">;
 def err_matrix_index_outside_range: Error<
   "matrix %select{row|column}0 index is outside the allowed range [0, %1)">;
 def err_matrix_incomplete_index: Error<
   "single subscript expressions are not allowed for matrix values">;
 def err_matrix_separate_incomplete_index: Error<
   "matrix row and column subscripts cannot be separated by any expression">;

 def err_loongarch_builtin_requires_la64 : Error<
   "this builtin requires target: loongarch64">;
 
 // WebAssembly reference type and table diagnostics.
 def err_wasm_reference_pr : Error<
   "%select{pointers|references}0 to WebAssembly reference types are illegal">;
 def err_wasm_ca_reference : Error<
   "cannot %select{capture|take address of}0 WebAssembly reference">;
+def err_wasm_addrof_table : Error<
+  "cannot take address of WebAssembly table">;
+def err_wasm_table_pointer : Error<
+  "pointers to WebAssembly tables are illegal">;
+def err_wasm_table_reference : Error<
+  "references to WebAssembly tables are illegal">;
+def err_typecheck_wasm_table_must_have_zero_length : Error<
+  "only zero-length WebAssembly tables are currently supported">;
+def err_wasm_table_in_function : Error<
+  "WebAssembly table cannot be declared within a function">;
+def err_wasm_table_as_function_argument : Error<
+  "cannot use WebAssembly table as a function argument">;
+def err_wasm_table_invalid_uett_operand : Error<
+  "invalid application of '%0' to WebAssembly table">;
+def err_wasm_cast_table : Error<
+  "cannot cast WebAssembly table">;
+def err_wasm_table_conditional_expression : Error<
+  "cannot use WebAssembly tables as the 2nd or 3rd operands of a conditional expression">;
+def err_wasm_table_assignment : Error<
+  "cannot assign WebAssembly table to a variable">;
+def err_wasm_table_return : Error<
+  "cannot return a WebAssembly table">;
+def err_wasm_table_throw : Error<
+  "cannot throw a WebAssembly table">;
+def err_wasm_table_catch : Error<
+  "cannot catch WebAssembly table">;
+def err_wasm_table_exception_spec : Error<
+  "WebAssembly table not allowed in exception sepcification">;
+def err_wasm_table_must_be_static : Error<
+  "WebAssembly table must be static">;
+def err_wasm_multidimensional_ref_array : Error<
+  "multi-dimensional arrays of WebAssembly references are illegal">;
+def err_wasm_builtin_arg_must_be_table_type : Error <
+  "%ordinal0 argument must be a WebAssembly table">;
+def err_wasm_builtin_arg_must_match_table_element_type : Error <
+  "%ordinal0 argument must match the element type of the WebAssembly table in the %ordinal1 argument">;
+def err_wasm_builtin_arg_must_be_integer_type : Error <
+  "%ordinal0 argument must be an integer">;
 } // end of sema component.

clang/include/clang/Basic/Specifiers.h

enum ExprObjectKind {
     OK_ObjCProperty,
 
     /// An Objective-C array/dictionary subscripting which reads an
     /// object or writes at the subscripted array/dictionary element via
     /// Objective-C method calls.
     OK_ObjCSubscript,
 
     /// A matrix component is a single element of a matrix.
-    OK_MatrixComponent
+    OK_MatrixComponent,
+
+    /// A table component is a single element of a WebAssembly table.
+    OK_TableComponent,
   };
 
   /// The reason why a DeclRefExpr does not constitute an odr-use.
   enum NonOdrUseReason {
     /// This is an odr-use.
     NOUR_None = 0,
     /// This name appears in an unevaluated operand.
     NOUR_Unevaluated,

clang/include/clang/Sema/Sema.h

private:
   ExprResult SemaBuiltinMatrixColumnMajorLoad(CallExpr *TheCall,
                                               ExprResult CallResult);
   ExprResult SemaBuiltinMatrixColumnMajorStore(CallExpr *TheCall,
                                                ExprResult CallResult);
 
   // WebAssembly builtin handling.
   bool BuiltinWasmRefNullExtern(CallExpr *TheCall);
   bool BuiltinWasmRefNullFunc(CallExpr *TheCall);
+  bool BuiltinWasmTableGet(CallExpr *TheCall);
+  bool BuiltinWasmTableSet(CallExpr *TheCall);
+  bool BuiltinWasmTableSize(CallExpr *TheCall);
+  bool BuiltinWasmTableGrow(CallExpr *TheCall);
+  bool BuiltinWasmTableFill(CallExpr *TheCall);
+  bool BuiltinWasmTableCopy(CallExpr *TheCall);
 
 public:
   enum FormatStringType {
     FST_Scanf,
     FST_Printf,
     FST_NSString,
     FST_Strftime,
     FST_Strfmon,

clang/include/clang/Serialization/ASTBitCodes.h

enum StmtCode {
   /// A SizefAlignOfExpr record.
   EXPR_SIZEOF_ALIGN_OF,
 
   /// An ArraySubscriptExpr record.
   EXPR_ARRAY_SUBSCRIPT,
 
   /// An MatrixSubscriptExpr record.
   EXPR_MATRIX_SUBSCRIPT,
   
   /// A CallExpr record.
   EXPR_CALL,
 
   /// A MemberExpr record.
   EXPR_MEMBER,
 
   /// A BinaryOperator record.
   EXPR_BINARY_OPERATOR,

clang/include/clang/Serialization/TypeBitCodes.def

 TYPE_BIT_CODE(DependentVector, DEPENDENT_SIZED_VECTOR, 48)
 TYPE_BIT_CODE(MacroQualified, MACRO_QUALIFIED, 49)
 TYPE_BIT_CODE(BitInt, BIT_INT, 50)
 TYPE_BIT_CODE(DependentBitInt, DEPENDENT_BIT_INT, 51)
 TYPE_BIT_CODE(ConstantMatrix, CONSTANT_MATRIX, 52)
 TYPE_BIT_CODE(DependentSizedMatrix, DEPENDENT_SIZE_MATRIX, 53)
 TYPE_BIT_CODE(Using, USING, 54)
 TYPE_BIT_CODE(BTFTagAttributed, BTFTAG_ATTRIBUTED, 55)
-
 #undef TYPE_BIT_CODE

clang/lib/AST/TextNodeDumper.cpp

if (E->containsErrors()) {
         OS << " objcsubscript";
         break;
       case OK_VectorComponent:
         OS << " vectorcomponent";
         break;
       case OK_MatrixComponent:
         OS << " matrixcomponent";
         break;
+      case OK_TableComponent:
+        OS << " tablecomponent";
+        break;
       }
     }
   }
 
   ConstStmtVisitor<TextNodeDumper>::Visit(Node);
 }
 
 void TextNodeDumper::Visit(const Type *T) {

clang/lib/AST/Type.cpp

#include "clang/Basic/WebAssemblyReferenceTypes.def"
       return true;
     default:
       return false;
     }
   }
   return false;
 }
 
-bool Type::isWebAssemblyReferenceType() const {
-  return isWebAssemblyExternrefType();
-}
-
 bool Type::isWebAssemblyExternrefType() const {
   if (const auto *BT = getAs<BuiltinType>())
     return BT->getKind() == BuiltinType::WasmExternRef;
   return false;
 }
 
+bool Type::isWebAssemblyTableType() const {
+  if (const auto *ATy = dyn_cast<ArrayType>(this)) {
+    return ATy->getElementType().isWebAssemblyReferenceType();
+  }
+  if (const auto *PTy = dyn_cast<PointerType>(this)) {
+    return PTy->getPointeeType().isWebAssemblyReferenceType();
+  }
+  return false;
+}
+
 bool Type::isSizelessType() const { return isSizelessBuiltinType(); }
 
 bool Type::isVLSTBuiltinType() const {
   if (const BuiltinType *BT = getAs<BuiltinType>()) {
     switch (BT->getKind()) {
     case BuiltinType::SveInt8:
     case BuiltinType::SveInt16:
     case BuiltinType::SveInt32:

 bool QualType::hasNonTrivialToPrimitiveDestructCUnion(const RecordDecl *RD) {
   return RD->hasNonTrivialToPrimitiveDestructCUnion();
 }
 
 bool QualType::hasNonTrivialToPrimitiveCopyCUnion(const RecordDecl *RD) {
   return RD->hasNonTrivialToPrimitiveCopyCUnion();
 }
 
+bool QualType::isWebAssemblyReferenceType() const {
+  return isWebAssemblyExternrefType() || isWebAssemblyFuncrefType();
+}
+
+bool QualType::isWebAssemblyExternrefType() const {
+  return getTypePtr()->isWebAssemblyExternrefType();
+}
+
+bool QualType::isWebAssemblyFuncrefType() const {
+  return getTypePtr()->isFunctionPointerType() && getAddressSpace() == LangAS::wasm_funcref;
+}
+
 QualType::PrimitiveDefaultInitializeKind
 QualType::isNonTrivialToPrimitiveDefaultInitialize() const {
   if (const auto *RT =
           getTypePtr()->getBaseElementTypeUnsafe()->getAs<RecordType>())
     if (RT->getDecl()->isNonTrivialToPrimitiveDefaultInitialize())
       return PDIK_Struct;
 
   switch (getQualifiers().getObjCLifetime()) {

clang/lib/Basic/Targets/WebAssembly.cpp

bool WebAssemblyTargetInfo::initFeatureMap(
     const std::vector<std::string> &FeaturesVec) const {
   if (CPU == "bleeding-edge") {
     Features["nontrapping-fptoint"] = true;
     Features["sign-ext"] = true;
     Features["bulk-memory"] = true;
     Features["atomics"] = true;
     Features["mutable-globals"] = true;
     Features["tail-call"] = true;
+    Features["reference-types"] = true;
     setSIMDLevel(Features, SIMD128, true);
   } else if (CPU == "generic") {
     Features["sign-ext"] = true;
     Features["mutable-globals"] = true;
   }
 
   return TargetInfo::initFeatureMap(Features, Diags, CPU, FeaturesVec);
 }

clang/lib/CodeGen/CGBuiltin.cpp

Value *CodeGenFunction::EmitWebAssemblyBuiltinExpr(unsigned BuiltinID,
   case WebAssembly::BI__builtin_wasm_relaxed_dot_bf16x8_add_f32_f32x4: {
     Value *LHS = EmitScalarExpr(E->getArg(0));
     Value *RHS = EmitScalarExpr(E->getArg(1));
     Value *Acc = EmitScalarExpr(E->getArg(2));
     Function *Callee =
         CGM.getIntrinsic(Intrinsic::wasm_relaxed_dot_bf16x8_add_f32);
     return Builder.CreateCall(Callee, {LHS, RHS, Acc});
   }
+  case WebAssembly::BI__builtin_wasm_table_get: {
+    assert(E->getArg(0)->getType()->isArrayType());
+    Value *Table =
+        EmitCastToVoidPtr(EmitArrayToPointerDecay(E->getArg(0)).getPointer());
+    Value *Index = EmitScalarExpr(E->getArg(1));
+    Function *Callee;
+    if (E->getType().isWebAssemblyExternrefType())
+      Callee = CGM.getIntrinsic(Intrinsic::wasm_table_get_externref);
+    else if (E->getType().isWebAssemblyFuncrefType())
+      Callee = CGM.getIntrinsic(Intrinsic::wasm_table_get_funcref);
+    else
+      llvm_unreachable(
+          "Unexpected reference type for __builtin_wasm_table_get");
+    return Builder.CreateCall(Callee, {Table, Index});
+  }
+  case WebAssembly::BI__builtin_wasm_table_set: {
+    assert(E->getArg(0)->getType()->isArrayType());
+    Value *Table =
+        EmitCastToVoidPtr(EmitArrayToPointerDecay(E->getArg(0)).getPointer());
+    Value *Index = EmitScalarExpr(E->getArg(1));
+    Value *Val = EmitScalarExpr(E->getArg(2));
+    Function *Callee;
+    if (E->getArg(2)->getType().isWebAssemblyExternrefType())
+      Callee = CGM.getIntrinsic(Intrinsic::wasm_table_set_externref);
+    else if (E->getArg(2)->getType().isWebAssemblyFuncrefType())
+      Callee = CGM.getIntrinsic(Intrinsic::wasm_table_set_funcref);
+    else
+      llvm_unreachable(
+          "Unexpected reference type for __builtin_wasm_table_set");
+    return Builder.CreateCall(Callee, {Table, Index, Val});
+  }
+  case WebAssembly::BI__builtin_wasm_table_size: {
+    assert(E->getArg(0)->getType()->isArrayType());
+    Value *Value =
+        EmitCastToVoidPtr(EmitArrayToPointerDecay(E->getArg(0)).getPointer());
+    Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_table_size);
+    return Builder.CreateCall(Callee, Value);
+  }
+  case WebAssembly::BI__builtin_wasm_table_grow: {
+    assert(E->getArg(0)->getType()->isArrayType());
+    Value *Table =
+        EmitCastToVoidPtr(EmitArrayToPointerDecay(E->getArg(0)).getPointer());
+    Value *Val = EmitScalarExpr(E->getArg(1));
+    Value *NElems = EmitScalarExpr(E->getArg(2));
+
+    Function *Callee;
+    if (E->getArg(1)->getType().isWebAssemblyExternrefType())
+      Callee = CGM.getIntrinsic(Intrinsic::wasm_table_grow_externref);
+    else if (E->getArg(2)->getType().isWebAssemblyFuncrefType())
+      Callee = CGM.getIntrinsic(Intrinsic::wasm_table_fill_funcref);
+    else
+      llvm_unreachable(
+          "Unexpected reference type for __builtin_wasm_table_grow");
+
+    return Builder.CreateCall(Callee, {Table, Val, NElems});
+  }
+  case WebAssembly::BI__builtin_wasm_table_fill: {
+    assert(E->getArg(0)->getType()->isArrayType());
+    Value *Table =
+        EmitCastToVoidPtr(EmitArrayToPointerDecay(E->getArg(0)).getPointer());
+    Value *Index = EmitScalarExpr(E->getArg(1));
+    Value *Val = EmitScalarExpr(E->getArg(2));
+    Value *NElems = EmitScalarExpr(E->getArg(3));
+
+    Function *Callee;
+    if (E->getArg(2)->getType().isWebAssemblyExternrefType())
+      Callee = CGM.getIntrinsic(Intrinsic::wasm_table_fill_externref);
+    else if (E->getArg(2)->getType().isWebAssemblyFuncrefType())
+      Callee = CGM.getIntrinsic(Intrinsic::wasm_table_fill_funcref);
+    else
+      llvm_unreachable(
+          "Unexpected reference type for __builtin_wasm_table_fill");
+
+    return Builder.CreateCall(Callee, {Table, Index, Val, NElems});
+  }
+  case WebAssembly::BI__builtin_wasm_table_copy: {
+    assert(E->getArg(0)->getType()->isArrayType());
+    Value *TableX =
+        EmitCastToVoidPtr(EmitArrayToPointerDecay(E->getArg(0)).getPointer());
+    Value *TableY =
+        EmitCastToVoidPtr(EmitArrayToPointerDecay(E->getArg(1)).getPointer());
+    Value *DstIdx = EmitScalarExpr(E->getArg(2));
+    Value *SrcIdx = EmitScalarExpr(E->getArg(3));
+    Value *NElems = EmitScalarExpr(E->getArg(4));
+
+    Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_table_copy);
+
+    return Builder.CreateCall(Callee, {TableX, TableY, SrcIdx, DstIdx, NElems});
+  }
   default:
     return nullptr;
   }
 }
 
 static std::pair<Intrinsic::ID, unsigned>
 getIntrinsicForHexagonNonClangBuiltin(unsigned BuiltinID) {
   struct Info {

clang/lib/CodeGen/CGExpr.cpp

 #include "clang/AST/NSAPI.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/CodeGenOptions.h"
 #include "clang/Basic/SourceManager.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/IntrinsicsWebAssembly.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/MatrixBuilder.h"
+#include "llvm/Passes/OptimizationLevel.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/SaveAndRestore.h"
 #include "llvm/Transforms/Utils/SanitizerStats.h"
 
 #include <string>
 
if (Ty->isConstantMatrixType()) {
     auto *ArrayTy = cast<llvm::ArrayType>(Result.getElementType());
     auto *VectorTy = llvm::FixedVectorType::get(ArrayTy->getElementType(),
                                                 ArrayTy->getNumElements());
 
     Result = Address(
         Builder.CreateBitCast(Result.getPointer(), VectorTy->getPointerTo()),
         VectorTy, Result.getAlignment());
   }
+  
   return Result;
 }
 
 Address CodeGenFunction::CreateMemTempWithoutCast(QualType Ty, CharUnits Align,
                                                   const Twine &Name) {
   return CreateTempAllocaWithoutCast(ConvertTypeForMem(Ty), Align, Name);
 }
 
if (LV.getQuals().getObjCLifetime() == Qualifiers::OCL_Weak) {
     return RValue::get(Object);
   }
 
   if (LV.isSimple()) {
     assert(!LV.getType()->isFunctionType());
 
     if (LV.getType()->isConstantMatrixType())
       return EmitLoadOfMatrixLValue(LV, Loc, *this);
     
     // Everything needs a load.
     return RValue::get(EmitLoadOfScalar(LV, Loc));
   }
 
   if (LV.isVectorElt()) {
     llvm::LoadInst *Load = Builder.CreateLoad(LV.getVectorAddress(),
                                               LV.isVolatileQualified());
     return RValue::get(Builder.CreateExtractElement(Load, LV.getVectorIdx(),
RValue CodeGenFunction::EmitLoadOfLValue(LValue LV, SourceLocation Loc) {
 
   if (LV.isMatrixElt()) {
     llvm::Value *Idx = LV.getMatrixIdx();
     if (CGM.getCodeGenOpts().OptimizationLevel > 0) {
       const auto *const MatTy = LV.getType()->castAs<ConstantMatrixType>();
       llvm::MatrixBuilder MB(Builder);
       MB.CreateIndexAssumption(Idx, MatTy->getNumElementsFlattened());
     }
+
     llvm::LoadInst *Load =
         Builder.CreateLoad(LV.getMatrixAddress(), LV.isVolatileQualified());
     return RValue::get(Builder.CreateExtractElement(Load, Idx, "matrixext"));
   }
 
   assert(LV.isBitField() && "Unknown LValue type!");
   return EmitLoadOfBitfieldLValue(LV, Loc);
 }

clang/lib/CodeGen/CGValue.h

 /// bitrange.
 class LValue {
   enum {
     Simple,       // This is a normal l-value, use getAddress().
     VectorElt,    // This is a vector element l-value (V[i]), use getVector*
     BitField,     // This is a bitfield l-value, use getBitfield*.
     ExtVectorElt, // This is an extended vector subset, use getExtVectorComp
     GlobalReg,    // This is a register l-value, use getGlobalReg()
-    MatrixElt     // This is a matrix element, use getVector*
+    MatrixElt,    // This is a matrix element, use getVector*
+    TableElt,     // This is a table element, use getTable*
   } LVType;
 
   llvm::Value *V;
   llvm::Type *ElementType;
 
   union {
     // Index into a vector subscript: V[i]
     llvm::Value *VectorIdx;

 
 public:
   bool isSimple() const { return LVType == Simple; }
   bool isVectorElt() const { return LVType == VectorElt; }
   bool isBitField() const { return LVType == BitField; }
   bool isExtVectorElt() const { return LVType == ExtVectorElt; }
   bool isGlobalReg() const { return LVType == GlobalReg; }
   bool isMatrixElt() const { return LVType == MatrixElt; }
+  bool isTableElt() const { return LVType == TableElt; }
 
   bool isVolatileQualified() const { return Quals.hasVolatile(); }
   bool isRestrictQualified() const { return Quals.hasRestrict(); }
   unsigned getVRQualifiers() const {
     return Quals.getCVRQualifiers() & ~Qualifiers::Const;
   }
 
   QualType getType() const { return Type; }
llvm::Value *getMatrixPointer() const {
     assert(isMatrixElt());
     return V;
   }
   llvm::Value *getMatrixIdx() const {
     assert(isMatrixElt());
     return VectorIdx;
   }
 
+  Address getTableAddress() const {
+    // FIXME: maybe this should not be possible.
+    return Address(getTablePointer(), ElementType, getAlignment());
+  }
+  llvm::Value *getTablePointer() const {
+    assert(isTableElt());
+    return V;
+  }
+  llvm::Value *getTableIdx() const {
+    assert(isTableElt());
+    return VectorIdx;
+  }
+
   // extended vector elements.
   Address getExtVectorAddress() const {
     return Address(getExtVectorPointer(), ElementType, getAlignment());
   }
   llvm::Value *getExtVectorPointer() const {
     assert(isExtVectorElt());
     return V;
   }
static LValue MakeMatrixElt(Address matAddress, llvm::Value *Idx,
     R.V = matAddress.getPointer();
     R.ElementType = matAddress.getElementType();
     R.VectorIdx = Idx;
     R.Initialize(type, type.getQualifiers(), matAddress.getAlignment(),
                  BaseInfo, TBAAInfo);
     return R;
   }
 
+  static LValue MakeTableElt(Address tabAddress, llvm::Value *Idx,
+                             QualType type, LValueBaseInfo BaseInfo,
+                             TBAAAccessInfo TBAAInfo) {
+    LValue R;
+    R.LVType = TableElt;
+    R.V = tabAddress.getPointer();
+    R.ElementType = tabAddress.getElementType();
+    R.VectorIdx = Idx;
+    R.Initialize(type, type.getQualifiers(), tabAddress.getAlignment(),
+                 BaseInfo, TBAAInfo);
+    return R;
+  }
+
   RValue asAggregateRValue(CodeGenFunction &CGF) const {
     return RValue::getAggregate(getAddress(CGF), isVolatileQualified());
   }
 };
 
 /// An aggregate value slot.
 class AggValueSlot {
   /// The address.

clang/lib/Sema/SemaCast.cpp

if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
     case OK_BitField:
       msg = diag::err_bad_cxx_cast_bitfield;
       return TC_NotApplicable;
       // FIXME: Use a specific diagnostic for the rest of these cases.
     case OK_VectorComponent: inappropriate = "vector element";      break;
     case OK_MatrixComponent:
       inappropriate = "matrix element";
       break;
+    case OK_TableComponent:
+      inappropriate = "table element";
+      break;
     case OK_ObjCProperty:    inappropriate = "property expression"; break;
     case OK_ObjCSubscript:   inappropriate = "container subscripting expression";
                              break;
     }
     if (inappropriate) {
       Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference)
           << inappropriate << DestType
           << OpRange << SrcExpr.get()->getSourceRange();
if (Self.ShouldSplatAltivecScalarInCast(vecTy) &&
         (SrcExpr.get()->getType()->isIntegerType() ||
          SrcExpr.get()->getType()->isFloatingType())) {
       Kind = CK_VectorSplat;
       SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get());
       return;
     }
   }
 
+  // WebAssembly tables cannot be cast.
+  QualType SrcType = SrcExpr.get()->getType();
+  if (SrcType->isWebAssemblyTableType()) {
+    Self.Diag(OpRange.getBegin(), diag::err_wasm_cast_table)
+        << SrcExpr.get()->getSourceRange();
+    SrcExpr = ExprError();
+    return;
+  }
+
   // C++ [expr.cast]p5: The conversions performed by
   //   - a const_cast,
   //   - a static_cast,
   //   - a static_cast followed by a const_cast,
   //   - a reinterpret_cast, or
   //   - a reinterpret_cast followed by a const_cast,
   //   can be performed using the cast notation of explicit type conversion.
   //   [...] If a conversion can be interpreted in more than one of the ways
else
       return;
     assert(SrcExpr.isUsable());
   }
   SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
   if (SrcExpr.isInvalid())
     return;
   QualType SrcType = SrcExpr.get()->getType();
 
+  if (SrcType->isWebAssemblyTableType()) {
+    Self.Diag(OpRange.getBegin(), diag::err_wasm_cast_table)
+        << SrcExpr.get()->getSourceRange();
+    SrcExpr = ExprError();
+    return;
+  }
+
   assert(!SrcType->isPlaceholderType());
 
   checkAddressSpaceCast(SrcType, DestType);
   if (SrcExpr.isInvalid())
     return;
 
   if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
                                diag::err_typecheck_cast_to_incomplete)) {

clang/lib/Sema/SemaChecking.cpp

 bool Sema::CheckWebAssemblyBuiltinFunctionCall(const TargetInfo &TI,
                                                unsigned BuiltinID,
                                                CallExpr *TheCall) {
   switch (BuiltinID) {
   case WebAssembly::BI__builtin_wasm_ref_null_extern:
     return BuiltinWasmRefNullExtern(TheCall);
   case WebAssembly::BI__builtin_wasm_ref_null_func:
     return BuiltinWasmRefNullFunc(TheCall);
+  case WebAssembly::BI__builtin_wasm_table_get:
+    return BuiltinWasmTableGet(TheCall);
+  case WebAssembly::BI__builtin_wasm_table_set:
+    return BuiltinWasmTableSet(TheCall);
+  case WebAssembly::BI__builtin_wasm_table_size:
+    return BuiltinWasmTableSize(TheCall);
+  case WebAssembly::BI__builtin_wasm_table_grow:
+    return BuiltinWasmTableGrow(TheCall);
+  case WebAssembly::BI__builtin_wasm_table_fill:
+    return BuiltinWasmTableFill(TheCall);
+  case WebAssembly::BI__builtin_wasm_table_copy:
+    return BuiltinWasmTableCopy(TheCall);
   }
 
   return false;
 }
 
 /// SemaBuiltinCpuSupports - Handle __builtin_cpu_supports(char *).
 /// This checks that the target supports __builtin_cpu_supports and
 /// that the string argument is constant and valid.
if (Op == OO_New || Op == OO_Array_New) {
         = FD->getType()->castAs<FunctionProtoType>();
       if (!Proto->isNothrow(/*ResultIfDependent*/true) &&
           CheckNonNullExpr(*this, RetValExp))
         Diag(ReturnLoc, diag::warn_operator_new_returns_null)
           << FD << getLangOpts().CPlusPlus11;
     }
   }
 
+  if (RetValExp && RetValExp->getType()->isWebAssemblyTableType()) {
+    Diag(ReturnLoc, diag::err_wasm_table_return);
+  }
+
   // PPC MMA non-pointer types are not allowed as return type. Checking the type
   // here prevent the user from using a PPC MMA type as trailing return type.
   if (Context.getTargetInfo().getTriple().isPPC64())
     CheckPPCMMAType(RetValExp->getType(), ReturnLoc);
 }
 
 /// Check for comparisons of floating-point values using == and !=. Issue a
 /// warning if the comparison is not likely to do what the programmer intended.
if (LangOpts.CPlusPlus && !Param->isInvalidDecl()) {
       // want to see if this function's declaration context is a record.
       DeclContext *DC = Param->getDeclContext();
       if (DC && DC->isFunctionOrMethod()) {
         if (auto *RD = dyn_cast<CXXRecordDecl>(DC->getParent()))
           CheckShadowInheritedFields(Param->getLocation(), Param->getDeclName(),
                                      RD, /*DeclIsField*/ false);
       }
     }
+
+    if (!Param->isInvalidDecl() &&
+        Param->getOriginalType()->isWebAssemblyTableType()) {
+      Param->setInvalidDecl();
+      HasInvalidParm = true;
+      Diag(Param->getLocation(), diag::err_wasm_table_as_function_argument);
+    }
   }
 
   return HasInvalidParm;
 }
 
 Optional<std::pair<CharUnits, CharUnits>>
 static getBaseAlignmentAndOffsetFromPtr(const Expr *E, ASTContext &Ctx);
 
ExprResult Sema::SemaBuiltinMatrixColumnMajorStore(CallExpr *TheCall,
   }
 
   if (ArgError)
     return ExprError();
 
   return CallResult;
 }
 
+/// Checks the argument at the given index is a WebAssembly table and if it
+/// is, sets ElTy to the element type.
+static bool CheckWasmBuiltinArgIsTable(Sema &S, CallExpr *E, unsigned ArgIndex,
+                                       QualType &ElTy) {
+  Expr *ArgExpr = E->getArg(ArgIndex);
+  const auto *ATy = dyn_cast<ArrayType>(ArgExpr->getType());
+  if (!ATy || !ATy->getElementType().isWebAssemblyReferenceType()) {
+    return S.Diag(ArgExpr->getBeginLoc(),
+                  diag::err_wasm_builtin_arg_must_be_table_type)
+           << ArgIndex + 1 << ArgExpr->getSourceRange();
+  }
+  ElTy = ATy->getElementType();
+  return false;
+}
+
+/// Checks the argument at the given index is an integer.
+static bool CheckWasmBuiltinArgIsInteger(Sema &S, CallExpr *E,
+                                         unsigned ArgIndex) {
+  Expr *ArgExpr = E->getArg(ArgIndex);
+  if (!ArgExpr->getType()->isIntegerType()) {
+    return S.Diag(ArgExpr->getBeginLoc(),
+                  diag::err_wasm_builtin_arg_must_be_integer_type)
+           << ArgIndex + 1 << ArgExpr->getSourceRange();
+  }
+  return false;
+}
+
+/// Check that the first argument is a WebAssembly table, and the second
+/// is an index to use as index into the table. 
+bool Sema::BuiltinWasmTableGet(CallExpr *TheCall) {
+  if (checkArgCount(*this, TheCall, 2))
+    return true;
+
+  QualType ElTy;
+  if (CheckWasmBuiltinArgIsTable(*this, TheCall, 0, ElTy))
+    return true;
+
+  if (CheckWasmBuiltinArgIsInteger(*this, TheCall, 1))
+    return true;
+
+  // If all is well, we set the type of TheCall to be the type of the
+  // element of the table.
+  // i.e. a table.get on an externref table has type externref,
+  // or whatever the type of the table element is.
+  TheCall->setType(ElTy);
+  
+  return false;
+}
+
+/// Check that the first argumnet is a WebAssembly table, the second is
+/// an index to use as index into the table and the third is the reference
+/// type to set into the table.
+bool Sema::BuiltinWasmTableSet(CallExpr *TheCall) {
+  if (checkArgCount(*this, TheCall, 3))
+    return true;
+
+  QualType ElTy;
+  if (CheckWasmBuiltinArgIsTable(*this, TheCall, 0, ElTy))
+    return true;
+
+  if (CheckWasmBuiltinArgIsInteger(*this, TheCall, 1))
+    return true;
+
+  if (!Context.hasSameType(ElTy, TheCall->getArg(2)->getType()))
+    return true;
+
+  return false;
+}
+
+/// Check that the argument is a WebAssembly table.
+bool Sema::BuiltinWasmTableSize(CallExpr *TheCall) {
+  if (checkArgCount(*this, TheCall, 1))
+    return true;
+
+  QualType ElTy;
+  if (CheckWasmBuiltinArgIsTable(*this, TheCall, 0, ElTy))
+    return true;
+
+  return false;
+}
+
+/// Check that the first argument is a WebAssembly table, the second is the
+/// value to use for new elements (of a type matching the table type), the
+/// third value is an integer.
+bool Sema::BuiltinWasmTableGrow(CallExpr *TheCall) {
+  if (checkArgCount(*this, TheCall, 3))
+    return true;
+
+  QualType ElTy;
+  if (CheckWasmBuiltinArgIsTable(*this, TheCall, 0, ElTy))
+    return true;
+
+  Expr *NewElemArg = TheCall->getArg(1);
+  if (!Context.hasSameType(ElTy, NewElemArg->getType())) {
+    return Diag(NewElemArg->getBeginLoc(),
+                diag::err_wasm_builtin_arg_must_match_table_element_type)
+           << 2 << 1 << NewElemArg->getSourceRange();
+  }
+
+  if (CheckWasmBuiltinArgIsInteger(*this, TheCall, 2))
+    return true;
+
+  return false;
+}
+
+/// Check that the first argument is a WebAssembly table, the second is an
+/// integer, the third is the value to use to fill the table (of a type
+/// matching the table type), and the fourth is an integer.
+bool Sema::BuiltinWasmTableFill(CallExpr *TheCall) {
+  if (checkArgCount(*this, TheCall, 4))
+    return true;
+
+  QualType ElTy;
+  if (CheckWasmBuiltinArgIsTable(*this, TheCall, 0, ElTy))
+    return true;
+
+  if (CheckWasmBuiltinArgIsInteger(*this, TheCall, 1))
+    return true;
+
+  Expr *NewElemArg = TheCall->getArg(2);
+  if (!Context.hasSameType(ElTy, NewElemArg->getType())) {
+    return Diag(NewElemArg->getBeginLoc(),
+                diag::err_wasm_builtin_arg_must_match_table_element_type)
+           << 3 << 1 << NewElemArg->getSourceRange();
+  }
+
+  if (CheckWasmBuiltinArgIsInteger(*this, TheCall, 3))
+    return true;
+
+  return false;
+}
+
+/// Check that the first argument is a WebAssembly table, the second is also a
+/// WebAssembly table (of the same element type), and the third to fifth
+/// arguments are integers.
+bool Sema::BuiltinWasmTableCopy(CallExpr *TheCall) {
+  if (checkArgCount(*this, TheCall, 5))
+    return true;
+
+  QualType XElTy;
+  if (CheckWasmBuiltinArgIsTable(*this, TheCall, 0, XElTy))
+    return true;
+
+  QualType YElTy;
+  if (CheckWasmBuiltinArgIsTable(*this, TheCall, 1, YElTy))
+    return true;
+
+  Expr *TableYArg = TheCall->getArg(1);
+  if (!Context.hasSameType(XElTy, YElTy)) {
+    return Diag(TableYArg->getBeginLoc(),
+                diag::err_wasm_builtin_arg_must_match_table_element_type)
+           << 2 << 1 << TableYArg->getSourceRange();
+  }
+
+  for (int I = 2; I <= 4; I++) {
+    if (CheckWasmBuiltinArgIsInteger(*this, TheCall, I))
+      return true;
+  }
+
+  return false;
+}
+
 /// \brief Enforce the bounds of a TCB
 /// CheckTCBEnforcement - Enforces that every function in a named TCB only
 /// directly calls other functions in the same TCB as marked by the enforce_tcb
 /// and enforce_tcb_leaf attributes.
 void Sema::CheckTCBEnforcement(const SourceLocation CallExprLoc,
                                const NamedDecl *Callee) {
   const NamedDecl *Caller = getCurFunctionOrMethodDecl();
 

clang/lib/Sema/SemaDecl.cpp

if (TSC != TSCS_unspecified) {
       Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
            diag::err_opencl_unknown_type_specifier)
           << getLangOpts().getOpenCLVersionString()
           << DeclSpec::getSpecifierName(TSC) << 1;
       NewVD->setInvalidDecl();
     }
   }
 
+  // WebAssembly tables are always in address space 1 (wasm_var). Don't apply
+  // address space if the table has local storage (semantic checks elsewhere
+  // will produce an error anyway).
+  if (const auto *ATy = dyn_cast<ArrayType>(NewVD->getType())) {
+    if (ATy && ATy->getElementType().isWebAssemblyReferenceType() &&
+        !NewVD->hasLocalStorage()) {
+      QualType Type = Context.getAddrSpaceQualType(
+          NewVD->getType(), Context.getLangASForBuiltinAddressSpace(1));
+      NewVD->setType(Type);
+    }
+  }
+
   // Handle attributes prior to checking for duplicates in MergeVarDecl
   ProcessDeclAttributes(S, NewVD, D);
 
   // FIXME: This is probably the wrong location to be doing this and we should
   // probably be doing this for more attributes (especially for function
   // pointer attributes such as format, warn_unused_result, etc.). Ideally
   // the code to copy attributes would be generated by TableGen.
   if (R->isFunctionPointerType())
if (!Previous.empty()) {
         << Name << computeDeclContext(D.getCXXScopeSpec(), true)
         << D.getCXXScopeSpec().getRange();
       NewVD->setInvalidDecl();
     }
 
     if (!IsVariableTemplateSpecialization)
       D.setRedeclaration(CheckVariableDeclaration(NewVD, Previous));
 
+    // CheckVariableDeclaration will set NewVD as invalid if something is in
+    // error like WebAssembly tables being declared as arrays with a non-zero
+    // size, but then parsing continues and emits further errors on that line.
+    // To avoid that we check here if it happened and return nullptr.
+    if (NewVD->getType()->isWebAssemblyTableType() && NewVD->isInvalidDecl())
+      return nullptr;
+
     if (NewTemplate) {
       VarTemplateDecl *PrevVarTemplate =
           NewVD->getPreviousDecl()
               ? NewVD->getPreviousDecl()->getDescribedVarTemplate()
               : nullptr;
 
       // Check the template parameter list of this declaration, possibly
       // merging in the template parameter list from the previous variable
if (NewVD->hasLocalStorage() && T.isObjCGCWeak()
     if (getLangOpts().getGC() != LangOptions::NonGC)
       Diag(NewVD->getLocation(), diag::warn_gc_attribute_weak_on_local);
     else {
       assert(!getLangOpts().ObjCAutoRefCount);
       Diag(NewVD->getLocation(), diag::warn_attribute_weak_on_local);
     }
   }
 
+  // WebAssembly tables must be static with a zero length and can't be
+  // declared within functions.
+  if (T->isWebAssemblyTableType()) {
+    if (getCurScope()->isFunctionScope()) {
+      Diag(NewVD->getLocation(), diag::err_wasm_table_in_function);
+      NewVD->setInvalidDecl();
+      return;
+    }
+    if (NewVD->getStorageClass() != SC_Static) {
+      Diag(NewVD->getLocation(), diag::err_wasm_table_must_be_static);
+      NewVD->setInvalidDecl();
+      return;
+    }
+    const auto *ATy = dyn_cast<ConstantArrayType>(T.getTypePtr());
+    if (!ATy || ATy->getSize().getSExtValue() != 0) {
+      Diag(NewVD->getLocation(),
+           diag::err_typecheck_wasm_table_must_have_zero_length);
+      NewVD->setInvalidDecl();
+      return;
+    }
+  }
+
   bool isVM = T->isVariablyModifiedType();
   if (isVM || NewVD->hasAttr<CleanupAttr>() ||
       NewVD->hasAttr<BlocksAttr>())
     setFunctionHasBranchProtectedScope();
 
   if ((isVM && NewVD->hasLinkage()) ||
       (T->isVariableArrayType() && NewVD->hasGlobalStorage())) {
     bool SizeIsNegative;
void Sema::CheckVariableDeclarationType(VarDecl *NewVD) {
 
   if (!NewVD->hasLocalStorage() && NewVD->hasAttr<BlocksAttr>()) {
     Diag(NewVD->getLocation(), diag::err_block_on_nonlocal);
     NewVD->setInvalidDecl();
     return;
   }
 
   if (!NewVD->hasLocalStorage() && T->isSizelessType() &&
-      !T->isWebAssemblyReferenceType()) {
+      !T.isWebAssemblyReferenceType()) {
     Diag(NewVD->getLocation(), diag::err_sizeless_nonlocal) << T;
     NewVD->setInvalidDecl();
     return;
   }
 
   if (isVM && NewVD->hasAttr<BlocksAttr>()) {
     Diag(NewVD->getLocation(), diag::err_block_on_vm);
     NewVD->setInvalidDecl();
if (getLangOpts().getOpenCLCompatibleVersion() >= 200) {
       if(const PipeType *PipeTy = PT->getAs<PipeType>()) {
         QualType ElemTy = PipeTy->getElementType();
           if (ElemTy->isReferenceType() || ElemTy->isPointerType()) {
             Diag(Param->getTypeSpecStartLoc(), diag::err_reference_pipe_type );
             D.setInvalidType();
           }
       }
     }
+    // WebAssembly tables can't be used as function parameters.
+    if (Context.getTargetInfo().getTriple().isWasm()) {
+      if (PT->getUnqualifiedDesugaredType()->isWebAssemblyTableType()) {
+        Diag(Param->getTypeSpecStartLoc(),
+             diag::err_wasm_table_as_function_argument);
+        D.setInvalidType();
+      }
+    }
   }
 
   // Here we have an function template explicit specialization at class scope.
   // The actual specialization will be postponed to template instatiation
   // time via the ClassScopeFunctionSpecializationDecl node.
   if (isDependentClassScopeExplicitSpecialization) {
     ClassScopeFunctionSpecializationDecl *NewSpec =
                          ClassScopeFunctionSpecializationDecl::Create(
void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
   VarDecl *VDecl = dyn_cast<VarDecl>(RealDecl);
   if (!VDecl) {
     assert(!isa<FieldDecl>(RealDecl) && "field init shouldn't get here");
     Diag(RealDecl->getLocation(), diag::err_illegal_initializer);
     RealDecl->setInvalidDecl();
     return;
   }
 
+  // WebAssembly tables can't be used to initialise a variable.
+  if (Init && !Init->getType().isNull() &&
+      Init->getType()->isWebAssemblyTableType()) {
+    Diag(Init->getExprLoc(), diag::err_wasm_table_assignment);
+    VDecl->setInvalidDecl();
+    return;
+  }
+
   // C++11 [decl.spec.auto]p6. Deduce the type which 'auto' stands in for.
   if (VDecl->getType()->isUndeducedType()) {
     // Attempt typo correction early so that the type of the init expression can
     // be deduced based on the chosen correction if the original init contains a
     // TypoExpr.
     ExprResult Res = CorrectDelayedTyposInExpr(Init, VDecl);
     if (!Res.isUsable()) {
       // There are unresolved typos in Init, just drop them.

clang/lib/Sema/SemaDeclCXX.cpp

if (!Invalid && (Mode == 0 || !BaseType->isVoidType()) &&
       !BaseType->isDependentType() && RequireCompleteType(Loc, BaseType, DK))
     Invalid = true;
 
   if (!Invalid && Mode != 1 && BaseType->isSizelessType()) {
     Diag(Loc, diag::err_catch_sizeless) << (Mode == 2 ? 1 : 0) << BaseType;
     Invalid = true;
   }
 
+  if (!Invalid && BaseType.isWebAssemblyReferenceType()) {
+    Diag(Loc, diag::err_wasm_table_catch);
+    Invalid = true;
+  }
+
   if (!Invalid && !ExDeclType->isDependentType() &&
       RequireNonAbstractType(Loc, ExDeclType,
                              diag::err_abstract_type_in_decl,
                              AbstractVariableType))
     Invalid = true;
 
   // Only the non-fragile NeXT runtime currently supports C++ catches
   // of ObjC types, and no runtime supports catching ObjC types by value.

clang/lib/Sema/SemaExceptionSpec.cpp

 
 /// CheckSpecifiedExceptionType - Check if the given type is valid in an
 /// exception specification. Incomplete types, or pointers to incomplete types
 /// other than void are not allowed.
 ///
 /// \param[in,out] T  The exception type. This will be decayed to a pointer type
 ///                   when the input is an array or a function type.
 bool Sema::CheckSpecifiedExceptionType(QualType &T, SourceRange Range) {
+
   // C++11 [except.spec]p2:
   //   A type cv T, "array of T", or "function returning T" denoted
   //   in an exception-specification is adjusted to type T, "pointer to T", or
   //   "pointer to function returning T", respectively.
   //
   // We also apply this rule in C++98.
   if (T->isArrayType())
     T = Context.getArrayDecayedType(T);
bool Sema::CheckSpecifiedExceptionType(QualType &T, SourceRange Range) {
   // The MSVC compatibility mode doesn't extend to sizeless types,
   // so diagnose them separately.
   if (PointeeT->isSizelessType() && Kind != 1) {
     Diag(Range.getBegin(), diag::err_sizeless_in_exception_spec)
         << (Kind == 2 ? 1 : 0) << PointeeT << Range;
     return true;
   }
 
+  // WebAssembly tables can't be used in exception specifications.
+  if (PointeeT.isWebAssemblyReferenceType()) {
+    Diag(Range.getBegin(), diag::err_wasm_table_exception_spec);
+    return true;
+  }
+
   return false;
 }
 
 /// CheckDistantExceptionSpec - Check if the given type is a pointer or pointer
 /// to member to a function with an exception specification. This means that
 /// it is invalid to add another level of indirection.
 bool Sema::CheckDistantExceptionSpec(QualType T) {
   // C++17 removes this rule in favor of putting exception specifications into

clang/lib/Sema/SemaExpr.cpp

if (Ty->isObjCObjectType())
       return VAK_Invalid;
     return VAK_Valid;
   }
 
   if (Ty.isDestructedType() == QualType::DK_nontrivial_c_struct)
     return VAK_Invalid;
 
   if (Context.getTargetInfo().getTriple().isWasm() &&
-      Ty->isWebAssemblyReferenceType()) {
+      Ty.isWebAssemblyReferenceType()) {
     return VAK_Invalid;
   }
 
   if (Ty.isCXX98PODType(Context))
     return VAK_Valid;
 
   // C++11 [expr.call]p7:
   //   Passing a potentially-evaluated argument of class type (Clause 9)
if (ExprKind == UETT_VecStep)
     return CheckVecStepTraitOperandType(*this, ExprTy, E->getExprLoc(),
                                         E->getSourceRange());
 
   // Explicitly list some types as extensions.
   if (!CheckExtensionTraitOperandType(*this, ExprTy, E->getExprLoc(),
                                       E->getSourceRange(), ExprKind))
     return false;
 
+  // WebAssembly tables are always illegal operands to unary expressions and
+  // type traits.
+  if (Context.getTargetInfo().getTriple().isWasm() &&
+      E->getType()->isWebAssemblyTableType()) {
+    Diag(E->getExprLoc(), diag::err_wasm_table_invalid_uett_operand)
+        << getTraitSpelling(ExprKind);
+    return true;
+  }
+
   // 'alignof' applied to an expression only requires the base element type of
   // the expression to be complete. 'sizeof' requires the expression's type to
   // be complete (and will attempt to complete it if it's an array of unknown
   // bound).
   if (ExprKind == UETT_AlignOf || ExprKind == UETT_PreferredAlignOf) {
     if (RequireCompleteSizedType(
             E->getExprLoc(), Context.getBaseElementType(E->getType()),
             diag::err_sizeof_alignof_incomplete_or_sizeless_type,
if (RequireCompleteSizedType(
     return true;
 
   if (ExprType->isFunctionType()) {
     Diag(OpLoc, diag::err_sizeof_alignof_function_type)
         << getTraitSpelling(ExprKind) << ExprRange;
     return true;
   }
 
+  // WebAssembly tables are always illegal operands to unary expressions and
+  // type traits.
+  if (Context.getTargetInfo().getTriple().isWasm() &&
+      ExprType->isWebAssemblyTableType()) {
+    Diag(OpLoc, diag::err_wasm_table_invalid_uett_operand)
+        << getTraitSpelling(ExprKind);
+    return true;
+  }
+
   if (CheckObjCTraitOperandConstraints(*this, ExprType, OpLoc, ExprRange,
                                        ExprKind))
     return true;
 
   return false;
 }
 
 static bool CheckAlignOfExpr(Sema &S, Expr *E, UnaryExprOrTypeTrait ExprKind) {
if (ResultType->isVoidType() && !getLangOpts().CPlusPlus) {
     Diag(LLoc, diag::ext_gnu_subscript_void_type)
       << BaseExpr->getSourceRange();
 
     // C forbids expressions of unqualified void type from being l-values.
     // See IsCForbiddenLValueType.
     if (!ResultType.hasQualifiers())
       VK = VK_PRValue;
   } else if (!ResultType->isDependentType() &&
+             !ResultType.isWebAssemblyReferenceType() &&
              RequireCompleteSizedType(
                  LLoc, ResultType,
                  diag::err_subscript_incomplete_or_sizeless_type, BaseExpr))
     return ExprError();
 
   assert(VK == VK_PRValue || LangOpts.CPlusPlus ||
          !ResultType.isCForbiddenLValueType());
 
ExprResult Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
   if (CheckCallReturnType(FuncT->getReturnType(), Fn->getBeginLoc(), TheCall,
                           FDecl))
     return ExprError();
 
   // We know the result type of the call, set it.
   TheCall->setType(FuncT->getCallResultType(Context));
   TheCall->setValueKind(Expr::getValueKindForType(FuncT->getReturnType()));
 
+  // WebAssembly tables can't be used as arguments.
+  if (Context.getTargetInfo().getTriple().isWasm()) {
+    for (const Expr *Arg : Args) {
+      if (Arg && Arg->getType()->isWebAssemblyTableType()) {
+        return ExprError(
+            Diag(Arg->getExprLoc(), diag::err_wasm_table_as_function_argument));
+      }
+    }
+  }
+
   if (Proto) {
     if (ConvertArgumentsForCall(TheCall, Fn, FDecl, Proto, Args, RParenLoc,
                                 IsExecConfig))
       return ExprError();
   } else {
     assert(isa<FunctionNoProtoType>(FuncT) && "Unknown FunctionType!");
 
     if (FDecl) {
return CheckVectorOperands(LHS, RHS, QuestionLoc, /*isCompAssign*/ false,
                                /*AllowBooleanOperation*/ false,
                                /*ReportInvalid*/ true);
 
   QualType ResTy =
       UsualArithmeticConversions(LHS, RHS, QuestionLoc, ACK_Conditional);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
 
+  // WebAssembly tables are not allowed as conditional LHS or RHS.
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
+  if (LHSTy->isWebAssemblyTableType() || RHSTy->isWebAssemblyTableType()) {
+    Diag(QuestionLoc, diag::err_wasm_table_conditional_expression)
+        << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
+    return QualType();
+  }
 
   // Diagnose attempts to convert between __ibm128, __float128 and long double
   // where such conversions currently can't be handled.
   if (unsupportedTypeConversion(*this, LHSTy, RHSTy)) {
     Diag(QuestionLoc,
          diag::err_typecheck_cond_incompatible_operands) << LHSTy << RHSTy
       << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
     return QualType();
QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
   diagnoseTautologicalComparison(*this, Loc, LHS.get(), RHS.get(), Opc);
 
   QualType LHSType = LHS.get()->getType();
   QualType RHSType = RHS.get()->getType();
   if ((LHSType->isArithmeticType() || LHSType->isEnumeralType()) &&
       (RHSType->isArithmeticType() || RHSType->isEnumeralType()))
     return checkArithmeticOrEnumeralCompare(*this, LHS, RHS, Loc, Opc);
 
+  if ((LHSType->isPointerType() &&
+       LHSType->getPointeeType().isWebAssemblyReferenceType()) ||
+      (RHSType->isPointerType() &&
+       RHSType->getPointeeType().isWebAssemblyReferenceType()))
+    return InvalidOperands(Loc, LHS, RHS);
+
   const Expr::NullPointerConstantKind LHSNullKind =
       LHS.get()->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull);
   const Expr::NullPointerConstantKind RHSNullKind =
       RHS.get()->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull);
   bool LHSIsNull = LHSNullKind != Expr::NPCK_NotNull;
   bool RHSIsNull = RHSNullKind != Expr::NPCK_NotNull;
 
   auto computeResultTy = [&]() {
if (const auto *DREHS = dyn_cast<DeclRefExpr>(HS.get())) {
       if (ECDHS && ECDHS->getInitVal() != 0 && ECDHS->getInitVal() != 1)
         EnumConstantInBoolContext = true;
     }
   }
 
   if (EnumConstantInBoolContext)
     Diag(Loc, diag::warn_enum_constant_in_bool_context);
 
+  // WebAssembly tables can't be used with logical operators.
+  QualType LHSTy = LHS.get()->getType();
+  QualType RHSTy = RHS.get()->getType();
+  const auto *LHSATy = dyn_cast<ArrayType>(LHSTy);
+  const auto *RHSATy = dyn_cast<ArrayType>(RHSTy);
+  if ((LHSATy && LHSATy->getElementType().isWebAssemblyReferenceType()) ||
+      (RHSATy && RHSATy->getElementType().isWebAssemblyReferenceType())) {
+    return InvalidOperands(Loc, LHS, RHS);
+  }
+
   // Diagnose cases where the user write a logical and/or but probably meant a
   // bitwise one.  We do this when the LHS is a non-bool integer and the RHS
   // is a constant.
   if (!EnumConstantInBoolContext && LHS.get()->getType()->isIntegerType() &&
       !LHS.get()->getType()->isBooleanType() &&
       RHS.get()->getType()->isIntegerType() && !RHS.get()->isValueDependent() &&
       // Don't warn in macros or template instantiations.
       !Loc.isMacroID() && !inTemplateInstantiation()) {
QualType Sema::CheckAssignmentOperands(Expr *LHSExpr, ExprResult &RHS,
   if (getLangOpts().OpenCL &&
       !getOpenCLOptions().isAvailableOption("cl_khr_fp16", getLangOpts()) &&
       LHSType->isHalfType()) {
     Diag(Loc, diag::err_opencl_half_load_store) << 1
         << LHSType.getUnqualifiedType();
     return QualType();
   }
 
+  // WebAssembly tables can't be used on RHS of an assignment expression.
+  if (RHSType->isWebAssemblyTableType()) {
+    Diag(Loc, diag::err_wasm_table_assignment);
+    return QualType();
+  }
+
   AssignConvertType ConvTy;
   if (CompoundType.isNull()) {
     Expr *RHSCheck = RHS.get();
 
     CheckIdentityFieldAssignment(LHSExpr, RHSCheck, Loc, *this);
 
     QualType LHSTy(LHSType);
     ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);

 
 namespace {
 enum {
   AO_Bit_Field = 0,
   AO_Vector_Element = 1,
   AO_Property_Expansion = 2,
   AO_Register_Variable = 3,
   AO_Matrix_Element = 4,
-  AO_No_Error = 5
+  AO_Table_Element = 5,
+  AO_No_Error = 6
 };
 }
 /// Diagnose invalid operand for address of operations.
 ///
 /// \param Type The type of operand which cannot have its address taken.
 static void diagnoseAddressOfInvalidType(Sema &S, SourceLocation Loc,
                                          Expr *E, unsigned Type) {
   S.Diag(Loc, diag::err_typecheck_address_of) << Type << E->getSourceRange();
if (lval == Expr::LV_ClassTemporary || lval == Expr::LV_ArrayTemporary) {
     // The operand cannot be a bit-field
     AddressOfError = AO_Bit_Field;
   } else if (op->getObjectKind() == OK_VectorComponent) {
     // The operand cannot be an element of a vector
     AddressOfError = AO_Vector_Element;
   } else if (op->getObjectKind() == OK_MatrixComponent) {
     // The operand cannot be an element of a matrix.
     AddressOfError = AO_Matrix_Element;
+  } else if (op->getObjectKind() == OK_TableComponent) {
+    // The operand cannot be an element of a table.
+    AddressOfError = AO_Table_Element;
   } else if (dcl) { // C99 6.5.3.2p1
     // We have an lvalue with a decl. Make sure the decl is not declared
     // with the register storage-class specifier.
     if (const VarDecl *vd = dyn_cast<VarDecl>(dcl)) {
       // in C++ it is not error to take address of a register
       // variable (c++03 7.1.1P3)
       if (vd->getStorageClass() == SC_Register &&
           !getLangOpts().CPlusPlus) {
if (lval == Expr::LV_IncompleteVoidType) {
     // Example: "extern void x; void* y = &x;".
     Diag(OpLoc, diag::ext_typecheck_addrof_void) << op->getSourceRange();
   }
 
   // If the operand has type "type", the result has type "pointer to type".
   if (op->getType()->isObjCObjectType())
     return Context.getObjCObjectPointerType(op->getType());
 
-  if (Context.getTargetInfo().getTriple().isWasm() &&
-      op->getType()->isWebAssemblyReferenceType()) {
+  // Cannot take the address of WebAssembly references or tables.
+  if (Context.getTargetInfo().getTriple().isWasm()) {
+    QualType OpTy = op->getType();
+    if (OpTy.isWebAssemblyReferenceType()) {
       Diag(OpLoc, diag::err_wasm_ca_reference)
           << 1 << OrigOp.get()->getSourceRange();
       return QualType();
     }
+    if (OpTy->isWebAssemblyTableType()) {
+      Diag(OpLoc, diag::err_wasm_addrof_table)
+          << OrigOp.get()->getSourceRange();
+      return QualType();
+    }
+  }
 
   CheckAddressOfPackedMember(op);
 
   return Context.getPointerType(op->getType());
 }
 
 static void RecordModifiableNonNullParam(Sema &S, const Expr *Exp) {
   const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Exp);
case UO_LNot: // logical negation
     resultType = Input.get()->getType();
 
     // Though we still have to promote half FP to float...
     if (resultType->isHalfType() && !Context.getLangOpts().NativeHalfType) {
       Input = ImpCastExprToType(Input.get(), Context.FloatTy, CK_FloatingCast).get();
       resultType = Context.FloatTy;
     }
 
+    // WebAsembly tables can't be used in unary expressions.
+    if (resultType->isPointerType() &&
+        resultType->getPointeeType().isWebAssemblyReferenceType()) {
+      return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
+                       << resultType << Input.get()->getSourceRange());
+    }
+
     if (resultType->isDependentType())
       break;
     if (resultType->isScalarType() && !isScopedEnumerationType(resultType)) {
       // C99 6.5.3.3p1: ok, fallthrough;
       if (Context.getLangOpts().CPlusPlus) {
         // C++03 [expr.unary.op]p8, C++0x [expr.unary.op]p9:
         // operand contextually converted to bool.
         Input = ImpCastExprToType(Input.get(), Context.BoolTy,
if (!Invalid && BD && S.LangOpts.OpenMP) {
     if (BuildAndDiagnose) {
       S.Diag(Loc, diag::err_capture_binding_openmp) << Var;
       S.Diag(Var->getLocation(), diag::note_entity_declared_at) << Var;
     }
     Invalid = true;
   }
 
   if (BuildAndDiagnose && S.Context.getTargetInfo().getTriple().isWasm() &&
-      CaptureType.getNonReferenceType()->isWebAssemblyReferenceType()) {
+      CaptureType.getNonReferenceType().isWebAssemblyReferenceType()) {
     S.Diag(Loc, diag::err_wasm_ca_reference) << 0;
     Invalid = true;
   }
 
   // Compute the type of the field that will capture this variable.
   if (ByRef) {
     // C++11 [expr.prim.lambda]p15:
     //   An entity is captured by reference if it is implicitly or

clang/lib/Sema/SemaExprCXX.cpp

if (!isPointer && Ty->isSizelessType()) {
       return true;
     }
 
     if (RequireNonAbstractType(ThrowLoc, ExceptionObjectTy,
                                diag::err_throw_abstract_type, E))
       return true;
   }
 
+  // Cannot throw WebAssembly tables (throwing WebAssembly references is
+  // caught earlier in this function).
+  if (Ty.isWebAssemblyReferenceType()) {
+    Diag(ThrowLoc, diag::err_wasm_table_throw) << E->getSourceRange();
+    return true;
+  }
+
   // If the exception has class type, we need additional handling.
   CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
   if (!RD)
     return false;
 
   // If we are throwing a polymorphic class type or pointer thereof,
   // exception handling will make use of the vtable.
   MarkVTableUsed(ThrowLoc, RD);
QualType Sema::CXXCheckConditionalOperands(ExprResult &Cond, ExprResult &LHS,
 
   // Neither is void.
   if (IsVectorConditional)
     return CheckVectorConditionalTypes(Cond, LHS, RHS, QuestionLoc);
 
   if (IsSizelessVectorConditional)
     return CheckSizelessVectorConditionalTypes(Cond, LHS, RHS, QuestionLoc);
 
+  // WebAssembly tables are not allowed as conditional LHS or RHS.
+  if (LTy->isWebAssemblyTableType() || RTy->isWebAssemblyTableType()) {
+    Diag(QuestionLoc, diag::err_wasm_table_conditional_expression)
+        << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
+    return QualType();
+  }
+  
   // C++11 [expr.cond]p3
   //   Otherwise, if the second and third operand have different types, and
   //   either has (cv) class type [...] an attempt is made to convert each of
   //   those operands to the type of the other.
   if (!Context.hasSameType(LTy, RTy) &&
       (LTy->isRecordType() || RTy->isRecordType())) {
     // These return true if a single direction is already ambiguous.
     QualType L2RType, R2LType;

clang/lib/Sema/SemaOverload.cpp

void OverloadCandidateSet::NoteCandidates(
     PartialDiagnosticAt PD, Sema &S, OverloadCandidateDisplayKind OCD,
     ArrayRef<Expr *> Args, StringRef Opc, SourceLocation OpLoc,
     llvm::function_ref<bool(OverloadCandidate &)> Filter) {
 
   auto Cands = CompleteCandidates(S, OCD, Args, OpLoc, Filter);
 
   S.Diag(PD.first, PD.second, shouldDeferDiags(S, Args, OpLoc));
 
+  // In WebAssembly we don't want to emit further diagnostics if a table is
+  // passed as an argument to a function.
+  bool NoteCands = true;
+  for (const Expr *Arg : Args) {
+    if (Arg->getType()->isWebAssemblyTableType())
+      NoteCands = false;
+  }
+  
+  if (NoteCands)
     NoteCandidates(S, Args, Cands, Opc, OpLoc);
 
   if (OCD == OCD_AmbiguousCandidates)
     MaybeDiagnoseAmbiguousConstraints(S, {begin(), end()});
 }
 
 void OverloadCandidateSet::NoteCandidates(Sema &S, ArrayRef<Expr *> Args,
                                           ArrayRef<OverloadCandidate *> Cands,
                                           StringRef Opc, SourceLocation OpLoc) {

clang/lib/Sema/SemaStmt.cpp

if (MD->hasRelatedResultType() && MD->getClassInterface()) {
       // type used to type-check the validity of return statements within the
       // method body is a pointer to the type of the class being implemented.
       RelatedRetType = Context.getObjCInterfaceType(MD->getClassInterface());
       RelatedRetType = Context.getObjCObjectPointerType(RelatedRetType);
     }
   } else // If we don't have a function/method context, bail.
     return StmtError();
 
+  if (RetValExp) {
+    const auto *ATy = dyn_cast<ArrayType>(RetValExp->getType());
+    if (ATy && ATy->getElementType().isWebAssemblyReferenceType()) {
+      Diag(ReturnLoc, diag::err_wasm_table_return);
+      return StmtError();
+    }
+  }
+
   // C++1z: discarded return statements are not considered when deducing a
   // return type.
   if (ExprEvalContexts.back().isDiscardedStatementContext() &&
       FnRetType->getContainedAutoType()) {
     if (RetValExp) {
       ExprResult ER =
           ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
       if (ER.isInvalid())

clang/lib/Sema/SemaType.cpp

QualType Sema::BuildPointerType(QualType T,
 
   // In ARC, it is forbidden to build pointers to unqualified pointers.
   if (getLangOpts().ObjCAutoRefCount)
     T = inferARCLifetimeForPointee(*this, T, Loc, /*reference*/ false);
 
   if (getLangOpts().OpenCL)
     T = deduceOpenCLPointeeAddrSpace(*this, T);
 
-  // In WebAssembly, pointers to reference types are illegal.
-  if (getASTContext().getTargetInfo().getTriple().isWasm() &&
-      T->isWebAssemblyReferenceType()) {
+  // In WebAssembly, pointers to reference types and pointers to tables are
+  // illegal.
+  if (getASTContext().getTargetInfo().getTriple().isWasm()) {
+    if (T.isWebAssemblyReferenceType()) {
       Diag(Loc, diag::err_wasm_reference_pr) << 0;
       return QualType();
     }
 
+    // We need to desugar the type here in case T is a ParenType.
+    if (T->getUnqualifiedDesugaredType()->isWebAssemblyTableType()) {
+      Diag(Loc, diag::err_wasm_table_pointer);
+      return QualType();
+    }
+  }
+
   // Build the pointer type.
   return Context.getPointerType(T);
 }
 
 /// Build a reference type.
 ///
 /// \param T The type to which we'll be building a reference.
 ///
QualType Sema::BuildReferenceType(QualType T, bool SpelledAsLValue,
 
   // In ARC, it is forbidden to build references to unqualified pointers.
   if (getLangOpts().ObjCAutoRefCount)
     T = inferARCLifetimeForPointee(*this, T, Loc, /*reference*/ true);
 
   if (getLangOpts().OpenCL)
     T = deduceOpenCLPointeeAddrSpace(*this, T);
 
-  // In WebAssembly, references to reference types are illegal.
+  // In WebAssembly, references to reference types and tables are illegal.
   if (getASTContext().getTargetInfo().getTriple().isWasm() &&
-      T->isWebAssemblyReferenceType()) {
+      T.isWebAssemblyReferenceType()) {
     Diag(Loc, diag::err_wasm_reference_pr) << 1;
     return QualType();
-  }
+  } 
+  if (T->isWebAssemblyTableType()) {
+    Diag(Loc, diag::err_wasm_table_reference);
+    return QualType();
+  }
 
   // Handle restrict on references.
   if (LValueRef)
     return Context.getLValueReferenceType(T, SpelledAsLValue);
   return Context.getRValueReferenceType(T);
 }
 
 /// Build a Read-only Pipe type.
if (getLangOpts().CPlusPlus) {
     if (Context.getTargetInfo().getCXXABI().isMicrosoft())
       if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>())
         if (!MPTy->getClass()->isDependentType())
           (void)isCompleteType(Loc, T);
 
   } else {
     // C99 6.7.5.2p1: If the element type is an incomplete or function type,
     // reject it (e.g. void ary[7], struct foo ary[7], void ary[7]())
-    if (RequireCompleteSizedType(Loc, T,
+    if (!T.isWebAssemblyReferenceType() &&
+        RequireCompleteSizedType(Loc, T,
                                  diag::err_array_incomplete_or_sizeless_type))
       return QualType();
   }
 
-  if (T->isSizelessType()) {
+  // Multi-dimensional arrays of WebAssembly references are not allowed.
+  if (Context.getTargetInfo().getTriple().isWasm() && T->isArrayType()) {
+    const auto *ATy = dyn_cast<ArrayType>(T);
+    if (ATy && ATy->getElementType().isWebAssemblyReferenceType()) {
+      Diag(Loc, diag::err_wasm_multidimensional_ref_array);
+      return QualType();
+    }
+  }
+
+  if (T->isSizelessType() && !T.isWebAssemblyReferenceType()) {
     Diag(Loc, diag::err_array_incomplete_or_sizeless_type) << 1 << T;
     return QualType();
   }
 
   if (T->isFunctionType()) {
     Diag(Loc, diag::err_illegal_decl_array_of_functions)
       << getPrintableNameForEntity(Entity) << T;
     return QualType();
if (ParamType->isVoidType()) {
       Diag(Loc, diag::err_param_with_void_type);
       Invalid = true;
     } else if (ParamType->isHalfType() && !getLangOpts().NativeHalfArgsAndReturns &&
                !Context.getTargetInfo().allowHalfArgsAndReturns()) {
       // Disallow half FP arguments.
       Diag(Loc, diag::err_parameters_retval_cannot_have_fp16_type) << 0 <<
         FixItHint::CreateInsertion(Loc, "*");
       Invalid = true;
+    } else if (ParamType->isWebAssemblyTableType()) {
+      Diag(Loc, diag::err_wasm_table_as_function_argument);
+      Invalid = true;
     }
 
     // C++2a [dcl.fct]p4:
     //   A parameter with volatile-qualified type is deprecated
     if (ParamType.isVolatileQualified() && getLangOpts().CPlusPlus20)
       Diag(Loc, diag::warn_deprecated_volatile_param) << ParamType;
 
     ParamTypes[Idx] = ParamType;

clang/test/CodeGen/WebAssembly/builtins-table.c

+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --function-signature
+// RUN: %clang_cc1 -triple wasm32 -target-feature +reference-types -disable-O0-optnone -emit-llvm %s -o - | opt -S -mem2reg | FileCheck %s
+// REQUIRES: webassembly-registered-target
+
+static __externref_t table[0];
+
+// CHECK-LABEL: define {{[^@]+}}@test_builtin_wasm_table_get
+// CHECK-SAME: (i32 noundef [[INDEX:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[TMP0:%.*]] = call ptr addrspace(10) @llvm.wasm.table.get.externref(ptr addrspace(1) @table, i32 [[INDEX]])
+// CHECK-NEXT:    ret ptr addrspace(10) [[TMP0]]
+//
+__externref_t test_builtin_wasm_table_get(int index) {
+  return __builtin_wasm_table_get(table, index);
+}
+
+// CHECK-LABEL: define {{[^@]+}}@test_builtin_wasm_table_set
+// CHECK-SAME: (i32 noundef [[INDEX:%.*]], ptr addrspace(10) [[REF:%.*]]) #[[ATTR0]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    call void @llvm.wasm.table.set.externref(ptr addrspace(1) @table, i32 [[INDEX]], ptr addrspace(10) [[REF]])
+// CHECK-NEXT:    ret void
+//
+void test_builtin_wasm_table_set(int index, __externref_t ref) {
+  return __builtin_wasm_table_set(table, index, ref);
+}
+
+// CHECK-LABEL: define {{[^@]+}}@test_builtin_wasm_table_size
+// CHECK-SAME: () #[[ATTR0]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[TMP0:%.*]] = call i32 @llvm.wasm.table.size(ptr addrspace(1) @table)
+// CHECK-NEXT:    ret i32 [[TMP0]]
+//
+int test_builtin_wasm_table_size() {
+  return __builtin_wasm_table_size(table);
+}
+
+// CHECK-LABEL: define {{[^@]+}}@test_builtin_wasm_table_grow
+// CHECK-SAME: (ptr addrspace(10) [[REF:%.*]], i32 noundef [[NELEM:%.*]]) #[[ATTR0]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[TMP0:%.*]] = call i32 @llvm.wasm.table.grow.externref(ptr addrspace(1) @table, ptr addrspace(10) [[REF]], i32 [[NELEM]])
+// CHECK-NEXT:    ret i32 [[TMP0]]
+//
+int test_builtin_wasm_table_grow(__externref_t ref, int nelem) {
+  return __builtin_wasm_table_grow(table, ref, nelem);
+}
+
+// CHECK-LABEL: define {{[^@]+}}@test_builtin_wasm_table_fill
+// CHECK-SAME: (i32 noundef [[INDEX:%.*]], ptr addrspace(10) [[REF:%.*]], i32 noundef [[NELEM:%.*]]) #[[ATTR0]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    call void @llvm.wasm.table.fill.externref(ptr addrspace(1) @table, i32 [[INDEX]], ptr addrspace(10) [[REF]], i32 [[NELEM]])
+// CHECK-NEXT:    ret void
+//
+void test_builtin_wasm_table_fill(int index, __externref_t ref, int nelem) {
+  __builtin_wasm_table_fill(table, index, ref, nelem);
+}
+
+static __externref_t other_table[0];
+
+// CHECK-LABEL: define {{[^@]+}}@test_table_copy
+// CHECK-SAME: (i32 noundef [[DST_IDX:%.*]], i32 noundef [[SRC_IDX:%.*]], i32 noundef [[NELEM:%.*]]) #[[ATTR0]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    call void @llvm.wasm.table.copy(ptr addrspace(1) @table, ptr addrspace(1) @other_table, i32 [[SRC_IDX]], i32 [[DST_IDX]], i32 [[NELEM]])
+// CHECK-NEXT:    ret void
+//
+void test_table_copy(int dst_idx, int src_idx, int nelem) {
+  __builtin_wasm_table_copy(table, other_table, dst_idx, src_idx, nelem);
+}

clang/test/CodeGen/WebAssembly/table.c

+// RUN: %clang_cc1 -triple wasm32 -target-feature +reference-types -o - -emit-llvm %s | FileCheck %s
+// REQUIRES: webassembly-registered-target
+
+// CHECK: @table = internal addrspace(1) global [0 x ptr addrspace(10)] zeroinitializer, align 1
+static __externref_t table[0];
+
+void use() {
+  // Ensure the table isn't discarded as unused.
+  table[0];
+}

clang/test/Sema/builtins-wasm.c

+// RUN: %clang_cc1 -fsyntax-only -verify -triple wasm32 -target-feature +reference-types %s
+
+static __externref_t table[0];
+
+void test_table_size(__externref_t ref, void *ptr, int arr[]) {
+  __builtin_wasm_table_size();                        // expected-error {{too few arguments to function call, expected 1, have 0}}
+  __builtin_wasm_table_size(1);                       // expected-error {{1st argument must be a WebAssembly table}}
+  __builtin_wasm_table_size(ref);                     // expected-error {{1st argument must be a WebAssembly table}}
+  __builtin_wasm_table_size(ptr);                     // expected-error {{1st argument must be a WebAssembly table}}
+  __builtin_wasm_table_size(arr);                     // expected-error {{1st argument must be a WebAssembly table}}
+  __builtin_wasm_table_size(table, table);            // expected-error {{too many arguments to function call, expected 1, have 2}}
+  void *a = __builtin_wasm_table_size(table);         // expected-error {{incompatible integer to pointer conversion initializing 'void *' with an expression of type 'int'}}
+  __externref_t b = __builtin_wasm_table_size(table); // expected-error {{initializing '__externref_t' with an expression of incompatible type 'int'}}
+  int c = __builtin_wasm_table_size(table);
+}
+
+void test_table_grow(__externref_t ref, int size) {
+  __builtin_wasm_table_grow();                           // expected-error {{too few arguments to function call, expected 3, have 0}}
+  __builtin_wasm_table_grow(table, table, table, table); // expected-error {{too many arguments to function call, expected 3, have 4}}
+  __builtin_wasm_table_grow(ref, ref, size);             // expected-error {{1st argument must be a WebAssembly table}}
+  __builtin_wasm_table_grow(table, table, size);         // expected-error {{2nd argument must match the element type of the WebAssembly table in the 1st argument}}
+  __builtin_wasm_table_grow(table, ref, table);          // expected-error {{3rd argument must be an integer}}
+  void *a = __builtin_wasm_table_grow(table, ref, size); // expected-error {{incompatible integer to pointer conversion initializing 'void *' with an expression of type 'int'}}
+  int b = __builtin_wasm_table_grow(table, ref, size);
+}
+
+void test_table_fill(int index, __externref_t ref, int nelem) {
+  __builtin_wasm_table_fill();                                   // expected-error {{too few arguments to function call, expected 4, have 0}}
+  __builtin_wasm_table_fill(table, table, table, table, table);  // expected-error {{too many arguments to function call, expected 4, have 5}}
+  __builtin_wasm_table_fill(index, index, ref, nelem);           // expected-error {{1st argument must be a WebAssembly table}}
+  __builtin_wasm_table_fill(table, table, ref, nelem);           // expected-error {{2nd argument must be an integer}}
+  __builtin_wasm_table_fill(table, index, index, ref);           // expected-error {{3rd argument must match the element type of the WebAssembly table in the 1st argument}}
+  __builtin_wasm_table_fill(table, index, ref, table);           // expected-error {{4th argument must be an integer}}
+  void *a = __builtin_wasm_table_fill(table, index, ref, nelem); // expected-error {{initializing 'void *' with an expression of incompatible type 'void'}}
+  __builtin_wasm_table_fill(table, index, ref, nelem);
+}
+
+void test_table_copy(int dst_idx, int src_idx, int nelem) {
+  __builtin_wasm_table_copy();                                         // expected-error {{too few arguments to function call, expected 5, have 0}}
+  __builtin_wasm_table_copy(table, table, table, table, table, table); // expected-error {{too many arguments to function call, expected 5, have 6}}
+  __builtin_wasm_table_copy(src_idx, table, dst_idx, src_idx, nelem);  // expected-error {{1st argument must be a WebAssembly table}}
+  __builtin_wasm_table_copy(table, src_idx, dst_idx, src_idx, nelem);  // expected-error {{2nd argument must be a WebAssembly table}}
+  __builtin_wasm_table_copy(table, table, table, src_idx, nelem);      // expected-error {{3rd argument must be an integer}}
+  __builtin_wasm_table_copy(table, table, dst_idx, table, nelem);      // expected-error {{4th argument must be an integer}}
+  __builtin_wasm_table_copy(table, table, dst_idx, src_idx, table);    // expected-error {{5th argument must be an integer}}
+  __builtin_wasm_table_copy(table, table, dst_idx, src_idx, nelem);
+}

clang/test/Sema/wasm-refs-and-tables.c

-// RUN: %clang_cc1 -fsyntax-only -verify -triple wasm32 -target-feature +reference-types %s
+// RUN: %clang_cc1 -fsyntax-only -verify -triple wasm32 -Wno-unused-value -target-feature +reference-types %s
 
 // Note: As WebAssembly references are sizeless types, we don't exhaustively
 // test for cases covered by sizeless-1.c and similar tests.
 
 // Unlike standard sizeless types, reftype globals are supported.
 __externref_t r1;
 extern __externref_t r2;
 static __externref_t r3;
 
 __externref_t *t1;               // expected-error {{pointers to WebAssembly reference types are illegal}}
 __externref_t **t2;              // expected-error {{pointers to WebAssembly reference types are illegal}}
 __externref_t ******t3;          // expected-error {{pointers to WebAssembly reference types are illegal}}
-static __externref_t t4[3];      // expected-error {{array has sizeless element type '__externref_t'}}
-static __externref_t t5[];       // expected-error {{array has sizeless element type '__externref_t'}}
-static __externref_t t6[] = {0}; // expected-error {{array has sizeless element type '__externref_t'}}
-__externref_t t7[0];             // expected-error {{array has sizeless element type '__externref_t'}}
-static __externref_t t8[0][0];   // expected-error {{array has sizeless element type '__externref_t'}}
+static __externref_t t4[3];      // expected-error {{only zero-length WebAssembly tables are currently supported}}
+static __externref_t t5[];       // expected-error {{only zero-length WebAssembly tables are currently supported}}
+static __externref_t t6[] = {0}; // expected-error {{only zero-length WebAssembly tables are currently supported}}
+__externref_t t7[0];             // expected-error {{WebAssembly table must be static}}
+static __externref_t t8[0][0];   // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+static __externref_t (*t9)[0];   // expected-error {{pointers to WebAssembly tables are illegal}}
 
-static __externref_t table[0]; // expected-error {{array has sizeless element type '__externref_t'}}
+static __externref_t table[0];
+static __externref_t other_table[0] = {};
 
 struct s {
   __externref_t f1;       // expected-error {{field has sizeless type '__externref_t'}}
-  __externref_t f2[0];    // expected-error {{array has sizeless element type '__externref_t'}}
-  __externref_t f3[];     // expected-error {{array has sizeless element type '__externref_t'}}
-  __externref_t f4[0][0]; // expected-error {{array has sizeless element type '__externref_t'}}
+  __externref_t f2[0];    // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f3[];     // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f4[0][0]; // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
   __externref_t *f5;      // expected-error {{pointers to WebAssembly reference types are illegal}}
   __externref_t ****f6;   // expected-error {{pointers to WebAssembly reference types are illegal}}
+  __externref_t (*f7)[0]; // expected-error {{pointers to WebAssembly tables are illegal}}
 };
 
 union u {
   __externref_t f1;       // expected-error {{field has sizeless type '__externref_t'}}
-  __externref_t f2[0];    // expected-error {{array has sizeless element type '__externref_t'}}
-  __externref_t f3[];     // expected-error {{array has sizeless element type '__externref_t'}}
-  __externref_t f4[0][0]; // expected-error {{array has sizeless element type '__externref_t'}}
+  __externref_t f2[0];    // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f3[];     // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f4[0][0]; // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
   __externref_t *f5;      // expected-error {{pointers to WebAssembly reference types are illegal}}
   __externref_t ****f6;   // expected-error {{pointers to WebAssembly reference types are illegal}}
+  __externref_t (*f7)[0]; // expected-error {{pointers to WebAssembly tables are illegal}}
 };
 
-void illegal_argument_1(__externref_t table[]);     // expected-error {{array has sizeless element type '__externref_t'}}
-void illegal_argument_2(__externref_t table[0][0]); // expected-error {{array has sizeless element type '__externref_t'}}
+void illegal_argument_1(__externref_t table[]);     // expected-error {{cannot use WebAssembly table as a function argument}}
+void illegal_argument_2(__externref_t table[0][0]); // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
 void illegal_argument_3(__externref_t *table);      // expected-error {{pointers to WebAssembly reference types are illegal}}
 void illegal_argument_4(__externref_t ***table);    // expected-error {{pointers to WebAssembly reference types are illegal}}
+void illegal_argument_5(__externref_t (*table)[0]); // expected-error {{pointers to WebAssembly tables are illegal}}
 
 __externref_t *illegal_return_1();   // expected-error {{pointers to WebAssembly reference types are illegal}}
 __externref_t ***illegal_return_2(); // expected-error {{pointers to WebAssembly reference types are illegal}}
+__externref_t (*illegal_return_3())[0]; // expected-error {{pointers to WebAssembly tables are illegal}}
 
 void varargs(int, ...);
 
 __externref_t func(__externref_t ref) {
   &ref; // expected-error {{cannot take address of WebAssembly reference}}
   int foo = 40;
   (__externref_t *)(&foo);     // expected-error {{pointers to WebAssembly reference types are illegal}}
   (__externref_t ****)(&foo);  // expected-error {{pointers to WebAssembly reference types are illegal}}
   sizeof(ref);                 // expected-error {{invalid application of 'sizeof' to sizeless type '__externref_t'}}
   sizeof(__externref_t);       // expected-error {{invalid application of 'sizeof' to sizeless type '__externref_t'}}
-  sizeof(__externref_t[0]);    // expected-error {{array has sizeless element type '__externref_t'}}
-  sizeof(__externref_t[0][0]); // expected-error {{array has sizeless element type '__externref_t'}}
+  sizeof(__externref_t[0]);    // expected-error {{invalid application of 'sizeof' to WebAssembly table}}
+  sizeof(table);               // expected-error {{invalid application of 'sizeof' to WebAssembly table}}
+  sizeof(__externref_t[0][0]); // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
   sizeof(__externref_t *);     // expected-error {{pointers to WebAssembly reference types are illegal}}
   sizeof(__externref_t ***);   // expected-error {{pointers to WebAssembly reference types are illegal}};
   // expected-warning@+1 {{'_Alignof' applied to an expression is a GNU extension}}
   _Alignof(ref);                 // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
   _Alignof(__externref_t);       // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
-  _Alignof(__externref_t[]);     // expected-error {{array has sizeless element type '__externref_t'}}
-  _Alignof(__externref_t[0][0]); // expected-error {{array has sizeless element type '__externref_t'}}
+  _Alignof(__externref_t[]);     // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
+  _Alignof(__externref_t[0]);    // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
+  _Alignof(table);               // expected-warning {{'_Alignof' applied to an expression is a GNU extension}} expected-error {{invalid application of 'alignof' to WebAssembly table}}
+  _Alignof(__externref_t[0][0]); // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
   _Alignof(__externref_t *);     // expected-error {{pointers to WebAssembly reference types are illegal}}
   _Alignof(__externref_t ***);   // expected-error {{pointers to WebAssembly reference types are illegal}};
   varargs(1, ref);               // expected-error {{cannot pass expression of type '__externref_t' to variadic function}}
 
+  __externref_t lt1[0];           // expected-error {{WebAssembly table cannot be declared within a function}}
+  static __externref_t lt2[0];    // expected-error {{WebAssembly table cannot be declared within a function}}
+  static __externref_t lt3[0][0]; // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+  static __externref_t(*lt4)[0];  // expected-error {{pointers to WebAssembly tables are illegal}}
+  illegal_argument_1(table);      // expected-error {{cannot use WebAssembly table as a function argument}}
+  varargs(1, table);              // expected-error {{cannot use WebAssembly table as a function argument}}
+  table == 1;                     // expected-error {{invalid operands to binary expression ('__attribute__((address_space(1))) __externref_t[0]' and 'int')}}
+  1 >= table;                     // expected-error {{invalid operands to binary expression ('int' and '__attribute__((address_space(1))) __externref_t[0]')}}
+  !table;                         // expected-error {{invalid argument type '__attribute__((address_space(1))) __externref_t *' to unary expression}}
+  1 && table;                     // expected-error {{invalid operands to binary expression ('int' and '__attribute__((address_space(1))) __externref_t[0]')}}
+  table || 1;                     // expected-error {{invalid operands to binary expression ('__attribute__((address_space(1))) __externref_t[0]' and 'int')}}
+  1 ? table : table;              // expected-error {{cannot use WebAssembly tables as the 2nd or 3rd operands of a conditional expression}}
+  (void *)table;                  // expected-error {{cannot cast WebAssembly table}}
+  void *u;
+  u = table;       // expected-error {{cannot assign WebAssembly table to a variable}}
+  void *v = table; // expected-error {{cannot assign WebAssembly table to a variable}}
+  &table;          // expected-error {{cannot take address of WebAssembly table}}
+
+  table[0];
+  table[0] = ref;
   return ref;
 }
+
+void *ret_void_ptr() {
+  return table; // expected-error {{cannot return a WebAssembly table}}
+}

clang/test/SemaCXX/wasm-refs-and-tables.cpp

+// RUN: %clang_cc1 -fsyntax-only -verify -triple wasm32 -Wno-unused-value -target-feature +reference-types %s
+
+// Note: As WebAssembly references are sizeless types, we don't exhaustively
+// test for cases covered by sizeless-1.c and similar tests.
+
+// Unlike standard sizeless types, reftype globals are supported.
+__externref_t r1;
+extern __externref_t r2;
+static __externref_t r3;
+
+__externref_t *t1;               // expected-error {{pointers to WebAssembly reference types are illegal}}
+__externref_t **t2;              // expected-error {{pointers to WebAssembly reference types are illegal}}
+__externref_t ******t3;          // expected-error {{pointers to WebAssembly reference types are illegal}}
+static __externref_t t4[3];      // expected-error {{only zero-length WebAssembly tables are currently supported}}
+static __externref_t t5[];       // expected-error {{only zero-length WebAssembly tables are currently supported}}
+static __externref_t t6[] = {0}; // expected-error {{only zero-length WebAssembly tables are currently supported}}
+__externref_t t7[0];             // expected-error {{WebAssembly table must be static}}
+static __externref_t t8[0][0];   // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+static __externref_t (*t9)[0];   // expected-error {{pointers to WebAssembly tables are illegal}}
+
+static __externref_t table[0];
+static __externref_t other_table[0] = {};
+
+struct s {
+  __externref_t f1;       // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f2[0];    // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f3[];     // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f4[0][0]; // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+  __externref_t *f5;      // expected-error {{pointers to WebAssembly reference types are illegal}}
+  __externref_t ****f6;   // expected-error {{pointers to WebAssembly reference types are illegal}}
+  __externref_t (*f7)[0]; // expected-error {{pointers to WebAssembly tables are illegal}}
+};
+
+union u {
+  __externref_t f1;       // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f2[0];    // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f3[];     // expected-error {{field has sizeless type '__externref_t'}}
+  __externref_t f4[0][0]; // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+  __externref_t *f5;      // expected-error {{pointers to WebAssembly reference types are illegal}}
+  __externref_t ****f6;   // expected-error {{pointers to WebAssembly reference types are illegal}}
+  __externref_t (*f7)[0]; // expected-error {{pointers to WebAssembly tables are illegal}}
+};
+
+void illegal_argument_1(__externref_t table[]);     // expected-error {{cannot use WebAssembly table as a function argument}}
+void illegal_argument_2(__externref_t table[0][0]); // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+void illegal_argument_3(__externref_t *table);      // expected-error {{pointers to WebAssembly reference types are illegal}}
+void illegal_argument_4(__externref_t ***table);    // expected-error {{pointers to WebAssembly reference types are illegal}}
+void illegal_argument_5(__externref_t (*table)[0]); // expected-error {{pointers to WebAssembly tables are illegal}}
+
+__externref_t *illegal_return_1();   // expected-error {{pointers to WebAssembly reference types are illegal}}
+__externref_t ***illegal_return_2(); // expected-error {{pointers to WebAssembly reference types are illegal}}
+__externref_t (*illegal_return_3())[0]; // expected-error {{pointers to WebAssembly tables are illegal}}
+
+void varargs(int, ...);
+
+__externref_t func(__externref_t ref) {
+  &ref; // expected-error {{cannot take address of WebAssembly reference}}
+  int foo = 40;
+  (__externref_t *)(&foo);     // expected-error {{pointers to WebAssembly reference types are illegal}}
+  (__externref_t ****)(&foo);  // expected-error {{pointers to WebAssembly reference types are illegal}}
+  sizeof(ref);                 // expected-error {{invalid application of 'sizeof' to sizeless type '__externref_t'}}
+  sizeof(__externref_t);       // expected-error {{invalid application of 'sizeof' to sizeless type '__externref_t'}}
+  sizeof(__externref_t[0]);    // expected-error {{invalid application of 'sizeof' to WebAssembly table}}
+  sizeof(table);               // expected-error {{invalid application of 'sizeof' to WebAssembly table}}
+  sizeof(__externref_t[0][0]); // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+  sizeof(__externref_t *);     // expected-error {{pointers to WebAssembly reference types are illegal}}
+  sizeof(__externref_t ***);   // expected-error {{pointers to WebAssembly reference types are illegal}};
+  // expected-warning@+1 {{'_Alignof' applied to an expression is a GNU extension}}
+  _Alignof(ref);                 // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
+  _Alignof(__externref_t);       // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
+  _Alignof(__externref_t[]);     // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
+  _Alignof(__externref_t[0]);    // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
+  _Alignof(table);               // expected-warning {{'_Alignof' applied to an expression is a GNU extension}} expected-error {{invalid application of 'alignof' to WebAssembly table}}
+  _Alignof(__externref_t[0][0]); // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+  _Alignof(__externref_t *);     // expected-error {{pointers to WebAssembly reference types are illegal}}
+  _Alignof(__externref_t ***);   // expected-error {{pointers to WebAssembly reference types are illegal}};
+  varargs(1, ref);               // expected-error {{cannot pass expression of type '__externref_t' to variadic function}}
+
+  __externref_t lt1[0];           // expected-error {{WebAssembly table cannot be declared within a function}}
+  static __externref_t lt2[0];    // expected-error {{WebAssembly table cannot be declared within a function}}
+  static __externref_t lt3[0][0]; // expected-error {{multi-dimensional arrays of WebAssembly references are illegal}}
+  static __externref_t(*lt4)[0];  // expected-error {{pointers to WebAssembly tables are illegal}}
+  illegal_argument_1(table);      // expected-error {{no matching function for call to 'illegal_argument_1'}}
+  varargs(1, table);              // expected-error {{cannot use WebAssembly table as a function argument}}
+  table == 1;                     // expected-error {{invalid operands to binary expression ('__attribute__((address_space(1))) __externref_t[0]' and 'int')}}
+  1 >= table;                     // expected-error {{invalid operands to binary expression ('int' and '__attribute__((address_space(1))) __externref_t[0]')}}
+  !table;                         // expected-error {{invalid argument type '__attribute__((address_space(1))) __externref_t *' to unary expression}}
+  1 && table;                     // expected-error {{invalid operands to binary expression ('int' and '__attribute__((address_space(1))) __externref_t[0]')}}
+  table || 1;                     // expected-error {{invalid operands to binary expression ('__attribute__((address_space(1))) __externref_t[0]' and 'int')}}
+  1 ? table : table;              // expected-error {{cannot use WebAssembly tables as the 2nd or 3rd operands of a conditional expression}}
+  (void *)table;                  // expected-error {{cannot cast WebAssembly table}}
+  void *u;
+  u = table;       // expected-error {{cannot assign WebAssembly table to a variable}}
+  void *v = table; // expected-error {{cannot assign WebAssembly table to a variable}}
+  &table;          // expected-error {{cannot take address of WebAssembly table}}
+
+  table[0];
+  table[0] = ref;
+  return ref;
+}
+
+void *ret_void_ptr() {
+  return table; // expected-error {{cannot return a WebAssembly table}}
+}

clang/test/SemaCXX/wasm-refs.cpp

-// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -std=gnu++11 -triple wasm32 -Wno-unused-value -target-feature +reference-types %s
-
-// This file tests C++ specific constructs with WebAssembly references and
-// tables. See wasm-refs-and-tables.c for C constructs.
-
-__externref_t ref;
-__externref_t &ref_ref1 = ref; // expected-error {{references to WebAssembly reference types are illegal}}
-__externref_t &ref_ref2(ref);  // expected-error {{references to WebAssembly reference types are illegal}}
-
-static __externref_t table[0];                    // expected-error {{array has sizeless element type '__externref_t'}}
-static __externref_t (&ref_to_table1)[0] = table; // expected-error {{array has sizeless element type '__externref_t'}}
-static __externref_t (&ref_to_table2)[0](table);  // expected-error {{array has sizeless element type '__externref_t'}}
-
-void illegal_argument_1(__externref_t &r); // expected-error {{references to WebAssembly reference types are illegal}}
-void illegal_argument_2(__externref_t (&t)[0]); // expected-error {{array has sizeless element type '__externref_t'}}
-
-__externref_t &illegal_return_1(); // expected-error {{references to WebAssembly reference types are illegal}}
-__externref_t (&illegal_return_2())[0]; // expected-error {{array has sizeless element type '__externref_t'}}
-
-void illegal_throw1() throw(__externref_t);   // expected-error {{sizeless type '__externref_t' is not allowed in exception specification}}
-void illegal_throw2() throw(__externref_t *); // expected-error {{pointers to WebAssembly reference types are illegal}}
-void illegal_throw3() throw(__externref_t &); // expected-error {{references to WebAssembly reference types are illegal}}
-void illegal_throw4() throw(__externref_t[0]); // expected-error {{array has sizeless element type '__externref_t'}}
-
-class RefClass {
-  __externref_t f1;       // expected-error {{field has sizeless type '__externref_t'}}
-  __externref_t f2[0];    // expected-error {{array has sizeless element type '__externref_t'}}
-  __externref_t f3[];     // expected-error {{array has sizeless element type '__externref_t'}}
-  __externref_t f4[0][0]; // expected-error {{array has sizeless element type '__externref_t'}}
-  __externref_t *f5;      // expected-error {{pointers to WebAssembly reference types are illegal}}
-  __externref_t ****f6;   // expected-error {{pointers to WebAssembly reference types are illegal}}
-  __externref_t (*f7)[0]; // expected-error {{array has sizeless element type '__externref_t'}}
-};
-
-struct AStruct {};
-
-template <typename T>
-struct TemplatedStruct {
-  T f; // expected-error {{field has sizeless type '__externref_t'}}
-  void foo(T);
-  T bar(void);
-  T arr[0]; // expected-error {{array has sizeless element type '__externref_t'}}
-  T *ptr;   // expected-error {{pointers to WebAssembly reference types are illegal}}
-};
-
-void func() {
-  int foo = 40;
-  static_cast<__externref_t>(foo);      // expected-error {{static_cast from 'int' to '__externref_t' is not allowed}}
-  static_cast<__externref_t *>(&foo);   // expected-error {{pointers to WebAssembly reference types are illegal}}
-  static_cast<int>(ref);                // expected-error {{static_cast from '__externref_t' to 'int' is not allowed}}
-  __externref_t(10);                    // expected-error {{functional-style cast from 'int' to '__externref_t' is not allowed}}
-  int i(ref);                           // expected-error {{cannot initialize a variable of type 'int' with an lvalue of type '__externref_t'}}
-  const_cast<__externref_t[0]>(table);  // expected-error {{array has sizeless element type '__externref_t'}}
-  const_cast<__externref_t *>(table);   // expected-error {{pointers to WebAssembly reference types are illegal}}
-  reinterpret_cast<__externref_t>(foo); // expected-error {{reinterpret_cast from 'int' to '__externref_t' is not allowed}}
-  reinterpret_cast<int>(ref);           // expected-error {{reinterpret_cast from '__externref_t' to 'int' is not allowed}}
-  int iarr[0];
-  reinterpret_cast<__externref_t[0]>(iarr); // expected-error {{array has sizeless element type '__externref_t'}}
-  reinterpret_cast<__externref_t *>(iarr);  // expected-error {{pointers to WebAssembly reference types are illegal}}
-  dynamic_cast<__externref_t>(foo);         // expected-error {{invalid target type '__externref_t' for dynamic_cast; target type must be a reference or pointer type to a defined class}}
-  dynamic_cast<__externref_t *>(&foo);      // expected-error {{pointers to WebAssembly reference types are illegal}}
-
-  TemplatedStruct<__externref_t> ts1;    // expected-note {{in instantiation}}
-  TemplatedStruct<__externref_t *> ts2;  // expected-error {{pointers to WebAssembly reference types are illegal}}
-  TemplatedStruct<__externref_t &> ts3;  // expected-error {{references to WebAssembly reference types are illegal}}
-  TemplatedStruct<__externref_t[0]> ts4; // expected-error {{array has sizeless element type '__externref_t'}}
-
-  auto auto_ref = ref;
-
-  auto fn1 = [](__externref_t x) { return x; };
-  auto fn2 = [](__externref_t *x) { return x; };   // expected-error {{pointers to WebAssembly reference types are illegal}}
-  auto fn3 = [](__externref_t &x) { return x; };   // expected-error {{references to WebAssembly reference types are illegal}}
-  auto fn4 = [](__externref_t x[0]) { return x; }; // expected-error {{array has sizeless element type '__externref_t'}}
-  auto fn5 = [&auto_ref](void) { return true; };   // expected-error {{cannot capture WebAssembly reference}}
-  auto fn6 = [auto_ref](void) { return true; };    // expected-error {{cannot capture WebAssembly reference}}
-  auto fn7 = [&](void) { auto_ref; return true; };                        // expected-error {{cannot capture WebAssembly reference}}
-  auto fn8 = [=](void) { auto_ref; return true; };                        // expected-error {{cannot capture WebAssembly reference}}
-
-  alignof(__externref_t);    // expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
-  alignof(ref);              // expected-warning {{'alignof' applied to an expression is a GNU extension}} expected-error {{invalid application of 'alignof' to sizeless type '__externref_t'}}
-  alignof(__externref_t[0]); // expected-error {{array has sizeless element type '__externref_t'}}
-
-  throw ref;  // expected-error {{cannot throw object of sizeless type '__externref_t'}}
-  throw &ref; // expected-error {{cannot take address of WebAssembly reference}}
-
-  try {
-  } catch (__externref_t) { // expected-error {{cannot catch sizeless type '__externref_t'}}
-  }
-  try {
-  } catch (__externref_t *) { // expected-error {{pointers to WebAssembly reference types are illegal}}
-  }
-  try {
-  } catch (__externref_t &) { // expected-error {{references to WebAssembly reference types are illegal}}
-  }
-  try {
-  } catch (__externref_t[0]) { // expected-error {{array has sizeless element type '__externref_t'}}
-  }
-
-  new __externref_t;    // expected-error {{allocation of sizeless type '__externref_t'}}
-  new __externref_t[0]; // expected-error {{allocation of sizeless type '__externref_t'}}
-
-  delete ref;     // expected-error {{cannot delete expression of type '__externref_t'}}
-}

llvm/include/llvm/CodeGen/WasmAddressSpaces.h

+//===--- llvm/CodeGen/WasmAddressSpaces.h -----------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Address Spaces for WebAssembly Type Handling
+//
+//===----------------------------------------------------------------------===//
+
+namespace llvm {
+
+namespace WebAssembly {
+
+enum WasmAddressSpace : unsigned {
+  // Default address space, for pointers to linear memory (stack, heap, data).
+  WASM_ADDRESS_SPACE_DEFAULT = 0,
+  // A non-integral address space for pointers to named objects outside of
+  // linear memory: WebAssembly globals or WebAssembly locals.  Loads and stores
+  // to these pointers are lowered to global.get / global.set or local.get /
+  // local.set, as appropriate.
+  WASM_ADDRESS_SPACE_VAR = 1,
+  // A non-integral address space for externref values
+  WASM_ADDRESS_SPACE_EXTERNREF = 10,
+  // A non-integral address space for funcref values
+  WASM_ADDRESS_SPACE_FUNCREF = 20,
+};
+
+inline bool isDefaultAddressSpace(unsigned AS) {
+  return AS == WASM_ADDRESS_SPACE_DEFAULT;
+}
+inline bool isWasmVarAddressSpace(unsigned AS) {
+  return AS == WASM_ADDRESS_SPACE_VAR;
+}
+inline bool isValidAddressSpace(unsigned AS) {
+  return isDefaultAddressSpace(AS) || isWasmVarAddressSpace(AS);
+}
+
+} // namespace WebAssembly
+
+} // namespace llvm
 No newline at end of file

llvm/include/llvm/IR/Type.h

 #define LLVM_IR_TYPE_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/CBindingWrapping.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/TypeSize.h"
+#include "llvm/CodeGen/WasmAddressSpaces.h"
 #include <cassert>
 #include <cstdint>
 #include <iterator>
 
 namespace llvm {
 
 class IntegerType;
 struct fltSemantics;
public:
   const fltSemantics &getFltSemantics() const;
 
   /// Return true if this is X86 MMX.
   bool isX86_MMXTy() const { return getTypeID() == X86_MMXTyID; }
 
   /// Return true if this is X86 AMX.
   bool isX86_AMXTy() const { return getTypeID() == X86_AMXTyID; }
 
+  /// Return true if this is a WebAssembly Reference Type.
+  bool isWebAssemblyReferenceType() const { return isWebAssemblyExternrefType() || isWebAssemblyFuncrefType(); }
+
+  /// Return true if this is a WebAssembly Externref Type.
+  bool isWebAssemblyExternrefType() const {
+    return getPointerAddressSpace() ==
+             WebAssembly::WasmAddressSpace::WASM_ADDRESS_SPACE_EXTERNREF;
+  }
+
+  /// Return true if this is a WebAssembly Funcref Type.
+  bool isWebAssemblyFuncrefType() const {
+    return getPointerAddressSpace() ==
+             WebAssembly::WasmAddressSpace::WASM_ADDRESS_SPACE_FUNCREF;
+  }
+
   /// Return true if this is a FP type or a vector of FP.
   bool isFPOrFPVectorTy() const { return getScalarType()->isFloatingPointTy(); }
 
   /// Return true if this is 'label'.
   bool isLabelTy() const { return getTypeID() == LabelTyID; }
 
   /// Return true if this is 'metadata'.
   bool isMetadataTy() const { return getTypeID() == MetadataTyID; }

llvm/lib/Target/WebAssembly/Utils/WebAssemblyTypeUtilities.h

enum class BlockType : unsigned {
   // Multivalue blocks (and other non-void blocks) are only emitted when the
   // blocks will never be exited and are at the ends of functions (see
   // WebAssemblyCFGStackify::fixEndsAtEndOfFunction). They also are never made
   // to pop values off the stack, so the exact multivalue signature can always
   // be inferred from the return type of the parent function in MCInstLower.
   Multivalue = 0xffff,
 };
 
-enum WasmAddressSpace : unsigned {
-  // Default address space, for pointers to linear memory (stack, heap, data).
-  WASM_ADDRESS_SPACE_DEFAULT = 0,
-  // A non-integral address space for pointers to named objects outside of
-  // linear memory: WebAssembly globals or WebAssembly locals.  Loads and stores
-  // to these pointers are lowered to global.get / global.set or local.get /
-  // local.set, as appropriate.
-  WASM_ADDRESS_SPACE_VAR = 1,
-  // A non-integral address space for externref values
-  WASM_ADDRESS_SPACE_EXTERNREF = 10,
-  // A non-integral address space for funcref values
-  WASM_ADDRESS_SPACE_FUNCREF = 20,
-};
-
-inline bool isDefaultAddressSpace(unsigned AS) {
-  return AS == WASM_ADDRESS_SPACE_DEFAULT;
-}
-inline bool isWasmVarAddressSpace(unsigned AS) {
-  return AS == WASM_ADDRESS_SPACE_VAR;
-}
-inline bool isValidAddressSpace(unsigned AS) {
-  return isDefaultAddressSpace(AS) || isWasmVarAddressSpace(AS);
-}
-inline bool isFuncrefType(const Type *Ty) {
-  return isa<PointerType>(Ty) &&
-         Ty->getPointerAddressSpace() ==
-             WasmAddressSpace::WASM_ADDRESS_SPACE_FUNCREF;
-}
-inline bool isExternrefType(const Type *Ty) {
-  return isa<PointerType>(Ty) &&
-         Ty->getPointerAddressSpace() ==
-             WasmAddressSpace::WASM_ADDRESS_SPACE_EXTERNREF;
-}
-inline bool isRefType(const Type *Ty) {
-  return isFuncrefType(Ty) || isExternrefType(Ty);
-}
-
 inline bool isRefType(wasm::ValType Type) {
   return Type == wasm::ValType::EXTERNREF || Type == wasm::ValType::FUNCREF;
 }
 
 // Convert StringRef to ValType / HealType / BlockType
 
 Optional<wasm::ValType> parseType(StringRef Type);
 BlockType parseBlockType(StringRef Type);

llvm/lib/Target/WebAssembly/Utils/WebAssemblyTypeUtilities.cpp

void WebAssembly::wasmSymbolSetType(MCSymbolWasm *Sym, const Type *GlobalVT,
   assert(!Sym->getType());
 
   // Tables are represented as Arrays in LLVM IR therefore
   // they reach this point as aggregate Array types with an element type
   // that is a reference type.
   wasm::ValType ValTy;
   bool IsTable = false;
   if (GlobalVT->isArrayTy() &&
-      WebAssembly::isRefType(GlobalVT->getArrayElementType())) {
+      GlobalVT->getArrayElementType()->isWebAssemblyReferenceType()) {
     IsTable = true;
     const Type *ElTy = GlobalVT->getArrayElementType();
-    if (WebAssembly::isExternrefType(ElTy))
+    if (ElTy->isWebAssemblyExternrefType())
       ValTy = wasm::ValType::EXTERNREF;
-    else if (WebAssembly::isFuncrefType(ElTy))
+    else if (ElTy->isWebAssemblyFuncrefType())
       ValTy = wasm::ValType::FUNCREF;
     else
       report_fatal_error("unhandled reference type");
   } else if (VTs.size() == 1) {
     ValTy = WebAssembly::toValType(VTs[0]);
   } else
     report_fatal_error("Aggregate globals not yet implemented");
 
   if (IsTable) {
     Sym->setType(wasm::WASM_SYMBOL_TYPE_TABLE);
     Sym->setTableType(ValTy);
   } else {
     Sym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL);
     Sym->setGlobalType(wasm::WasmGlobalType{uint8_t(ValTy), /*Mutable=*/true});
   }
 }

llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp

for (const auto &In : Ins) {
     // Ignore In.getNonZeroOrigAlign() because all our arguments are passed in
     // registers.
     InTys.push_back(In.VT);
   }
 
   // Lastly, if this is a call to a funcref we need to add an instruction
   // table.set to the chain and transform the call.
   if (CLI.CB &&
-      WebAssembly::isFuncrefType(CLI.CB->getCalledOperand()->getType())) {
+      CLI.CB->getCalledOperand()->getType()->isWebAssemblyFuncrefType()) {
     // In the absence of function references proposal where a funcref call is
     // lowered to call_ref, using reference types we generate a table.set to set
     // the funcref to a special table used solely for this purpose, followed by
     // a call_indirect. Here we just generate the table set, and return the
     // SDValue of the table.set so that LowerCall can finalize the lowering by
     // generating the call_indirect.
     SDValue Chain = Ops[0];
 

llvm/lib/Target/WebAssembly/WebAssemblyLowerRefTypesIntPtrConv.cpp

bool WebAssemblyLowerRefTypesIntPtrConv::runOnFunction(Function &F) {
   // We replace the instruction by a trap instruction
   // and its uses by null in the case of inttoptr and 0 in the
   // case of ptrtoint.
   std::set<Instruction *> worklist;
 
   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
     PtrToIntInst *PTI = dyn_cast<PtrToIntInst>(&*I);
     IntToPtrInst *ITP = dyn_cast<IntToPtrInst>(&*I);
-    if (!(PTI && WebAssembly::isRefType(PTI->getPointerOperand()->getType())) &&
-        !(ITP && WebAssembly::isRefType(ITP->getDestTy())))
+    if (!(PTI &&
+          PTI->getPointerOperand()->getType()->isWebAssemblyReferenceType()) &&
+        !(ITP && ITP->getDestTy()->isWebAssemblyReferenceType()))
       continue;
 
     UndefValue *U = UndefValue::get(I->getType());
     I->replaceAllUsesWith(U);
 
     Function *TrapIntrin =
         Intrinsic::getDeclaration(F.getParent(), Intrinsic::debugtrap);
     CallInst::Create(TrapIntrin, {}, "", &*I);