[WebAssembly][Clang] Add __builtin_wasm_ref_is_null_extern #139580

hoodmane · 2025-05-12T17:02:11Z

I also fixed __builtin_wasm_ref_null_extern() to generate a diagnostic when it gets an argument. It seems like SemaRef.checkArgCount() has a bug that makes it unable to check for 0 args.

cc @sbc100 @pmatos

I also fixed __builtin_wasm_ref_null_extern() to generate a diagnostic when it gets an argument. It seems like `SemaRef.checkArgCount()` has a bug that makes it unable to check for 0 args.

llvmbot · 2025-05-12T17:02:41Z

@llvm/pr-subscribers-backend-webassembly

Author: Hood Chatham (hoodmane)

Changes

I also fixed __builtin_wasm_ref_null_extern() to generate a diagnostic when it gets an argument. It seems like SemaRef.checkArgCount() has a bug that makes it unable to check for 0 args.

cc @sbc100 @pmatos

Full diff: https://github.com/llvm/llvm-project/pull/139580.diff

7 Files Affected:

(modified) clang/include/clang/Basic/BuiltinsWebAssembly.def (+1)
(modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+2)
(modified) clang/include/clang/Sema/SemaWasm.h (+1)
(modified) clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp (+5)
(modified) clang/lib/Sema/SemaWasm.cpp (+24-2)
(modified) clang/test/CodeGen/builtins-wasm.c (+6)
(modified) clang/test/Sema/builtins-wasm.c (+4)

diff --git a/clang/include/clang/Basic/BuiltinsWebAssembly.def b/clang/include/clang/Basic/BuiltinsWebAssembly.def
index ab480369b3820..e2afcc08064b2 100644
--- a/clang/include/clang/Basic/BuiltinsWebAssembly.def
+++ b/clang/include/clang/Basic/BuiltinsWebAssembly.def
@@ -192,6 +192,7 @@ TARGET_BUILTIN(__builtin_wasm_replace_lane_f16x8, "V8hV8hIif", "nc", "fp16")
 // in which case the argument spec (second argument) is unused.
 
 TARGET_BUILTIN(__builtin_wasm_ref_null_extern, "i", "nct", "reference-types")
+TARGET_BUILTIN(__builtin_wasm_ref_is_null_extern, "ii", "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
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index e5a7cdc14a737..d4abc46ae58ee 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -12991,6 +12991,8 @@ def err_wasm_reftype_multidimensional_array : Error<
   "multi-dimensional arrays of WebAssembly references are not allowed">;
 def err_wasm_builtin_arg_must_be_table_type : Error <
   "%ordinal0 argument must be a WebAssembly table">;
+def err_wasm_builtin_arg_must_be_externref_type : Error <
+  "%ordinal0 argument must be an externref">;
 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 <
diff --git a/clang/include/clang/Sema/SemaWasm.h b/clang/include/clang/Sema/SemaWasm.h
index 8841fdff23035..2123e073516cb 100644
--- a/clang/include/clang/Sema/SemaWasm.h
+++ b/clang/include/clang/Sema/SemaWasm.h
@@ -29,6 +29,7 @@ class SemaWasm : public SemaBase {
                                            CallExpr *TheCall);
 
   bool BuiltinWasmRefNullExtern(CallExpr *TheCall);
+  bool BuiltinWasmRefIsNullExtern(CallExpr *TheCall);
   bool BuiltinWasmRefNullFunc(CallExpr *TheCall);
   bool BuiltinWasmTableGet(CallExpr *TheCall);
   bool BuiltinWasmTableSet(CallExpr *TheCall);
diff --git a/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp b/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
index 698f43215a1be..b7fd70e855d40 100644
--- a/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
+++ b/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
@@ -209,6 +209,11 @@ Value *CodeGenFunction::EmitWebAssemblyBuiltinExpr(unsigned BuiltinID,
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_null_extern);
     return Builder.CreateCall(Callee);
   }
+  case WebAssembly::BI__builtin_wasm_ref_is_null_extern: {
+    Value *Src = EmitScalarExpr(E->getArg(0));
+    Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_is_null_extern);
+    return Builder.CreateCall(Callee, {Src});
+  }
   case WebAssembly::BI__builtin_wasm_ref_null_func: {
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_null_func);
     return Builder.CreateCall(Callee);
diff --git a/clang/lib/Sema/SemaWasm.cpp b/clang/lib/Sema/SemaWasm.cpp
index c0fa05bc17609..4157e179c97d6 100644
--- a/clang/lib/Sema/SemaWasm.cpp
+++ b/clang/lib/Sema/SemaWasm.cpp
@@ -52,14 +52,34 @@ static bool CheckWasmBuiltinArgIsInteger(Sema &S, CallExpr *E,
 }
 
 bool SemaWasm::BuiltinWasmRefNullExtern(CallExpr *TheCall) {
-  if (TheCall->getNumArgs() != 0)
+  if (TheCall->getNumArgs() != 0) {
+    Diag(TheCall->getBeginLoc(), diag::err_typecheck_call_too_many_args)
+        << 0 /*function call*/ << /*expected*/ 0 << TheCall->getNumArgs()
+        << /*is non object*/ 0;
     return true;
-
+  }
   TheCall->setType(getASTContext().getWebAssemblyExternrefType());
 
   return false;
 }
 
+bool SemaWasm::BuiltinWasmRefIsNullExtern(CallExpr *TheCall) {
+  if (SemaRef.checkArgCount(TheCall, 1)) {
+    return true;
+  }
+
+  Expr *ArgExpr = TheCall->getArg(0);
+  if (!ArgExpr->getType().isWebAssemblyExternrefType()) {
+    SemaRef.Diag(ArgExpr->getBeginLoc(),
+                  diag::err_wasm_builtin_arg_must_be_externref_type)
+           << 1 << ArgExpr->getSourceRange();
+    return true;
+  }
+
+  return false;
+}
+
+
 bool SemaWasm::BuiltinWasmRefNullFunc(CallExpr *TheCall) {
   ASTContext &Context = getASTContext();
   if (TheCall->getNumArgs() != 0) {
@@ -224,6 +244,8 @@ bool SemaWasm::CheckWebAssemblyBuiltinFunctionCall(const TargetInfo &TI,
     return BuiltinWasmRefNullExtern(TheCall);
   case WebAssembly::BI__builtin_wasm_ref_null_func:
     return BuiltinWasmRefNullFunc(TheCall);
+  case WebAssembly::BI__builtin_wasm_ref_is_null_extern:
+    return BuiltinWasmRefIsNullExtern(TheCall);
   case WebAssembly::BI__builtin_wasm_table_get:
     return BuiltinWasmTableGet(TheCall);
   case WebAssembly::BI__builtin_wasm_table_set:
diff --git a/clang/test/CodeGen/builtins-wasm.c b/clang/test/CodeGen/builtins-wasm.c
index 263cfd3ab4c69..4a44a9a88df11 100644
--- a/clang/test/CodeGen/builtins-wasm.c
+++ b/clang/test/CodeGen/builtins-wasm.c
@@ -741,6 +741,12 @@ __externref_t externref_null() {
   // WEBASSEMBLY-NEXT: ret
 }
 
+int externref_is_null(__externref_t arg) {
+  return __builtin_wasm_ref_is_null_extern(arg);
+  // WEBASSEMBLY: tail call i32 @llvm.wasm.ref.is_null.extern(ptr addrspace(10) %arg)
+  // WEBASSEMBLY-NEXT: ret
+}
+
 void *tp (void) {
   return __builtin_thread_pointer ();
   // WEBASSEMBLY: call {{.*}} @llvm.thread.pointer()
diff --git a/clang/test/Sema/builtins-wasm.c b/clang/test/Sema/builtins-wasm.c
index beb430616233a..31e5291d3ae5e 100644
--- a/clang/test/Sema/builtins-wasm.c
+++ b/clang/test/Sema/builtins-wasm.c
@@ -7,6 +7,10 @@ static __externref_t table[0];
 typedef void (*__funcref funcref_t)();
 void test_ref_null() {
   funcref_t func = __builtin_wasm_ref_null_func(0); // expected-error {{too many arguments to function call, expected 0, have 1}}
+  __externref_t ref = __builtin_wasm_ref_null_extern(0); // expected-error {{too many arguments to function call, expected 0, have 1}}
+  __builtin_wasm_ref_is_null_extern(ref, 1); // expected-error {{too many arguments to function call, expected 1, have 2}}
+  __builtin_wasm_ref_is_null_extern(); // expected-error {{too few arguments to function call, expected 1, have 0}}
+  __builtin_wasm_ref_is_null_extern(1); // expected-error {{1st argument must be an externref}}
 }
 
 void test_table_size(__externref_t ref, void *ptr, int arr[]) {

llvmbot · 2025-05-12T17:02:42Z

@llvm/pr-subscribers-clang

Author: Hood Chatham (hoodmane)

Changes

I also fixed __builtin_wasm_ref_null_extern() to generate a diagnostic when it gets an argument. It seems like SemaRef.checkArgCount() has a bug that makes it unable to check for 0 args.

cc @sbc100 @pmatos

Full diff: https://github.com/llvm/llvm-project/pull/139580.diff

7 Files Affected:

(modified) clang/include/clang/Basic/BuiltinsWebAssembly.def (+1)
(modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+2)
(modified) clang/include/clang/Sema/SemaWasm.h (+1)
(modified) clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp (+5)
(modified) clang/lib/Sema/SemaWasm.cpp (+24-2)
(modified) clang/test/CodeGen/builtins-wasm.c (+6)
(modified) clang/test/Sema/builtins-wasm.c (+4)

diff --git a/clang/include/clang/Basic/BuiltinsWebAssembly.def b/clang/include/clang/Basic/BuiltinsWebAssembly.def
index ab480369b3820..e2afcc08064b2 100644
--- a/clang/include/clang/Basic/BuiltinsWebAssembly.def
+++ b/clang/include/clang/Basic/BuiltinsWebAssembly.def
@@ -192,6 +192,7 @@ TARGET_BUILTIN(__builtin_wasm_replace_lane_f16x8, "V8hV8hIif", "nc", "fp16")
 // in which case the argument spec (second argument) is unused.
 
 TARGET_BUILTIN(__builtin_wasm_ref_null_extern, "i", "nct", "reference-types")
+TARGET_BUILTIN(__builtin_wasm_ref_is_null_extern, "ii", "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
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index e5a7cdc14a737..d4abc46ae58ee 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -12991,6 +12991,8 @@ def err_wasm_reftype_multidimensional_array : Error<
   "multi-dimensional arrays of WebAssembly references are not allowed">;
 def err_wasm_builtin_arg_must_be_table_type : Error <
   "%ordinal0 argument must be a WebAssembly table">;
+def err_wasm_builtin_arg_must_be_externref_type : Error <
+  "%ordinal0 argument must be an externref">;
 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 <
diff --git a/clang/include/clang/Sema/SemaWasm.h b/clang/include/clang/Sema/SemaWasm.h
index 8841fdff23035..2123e073516cb 100644
--- a/clang/include/clang/Sema/SemaWasm.h
+++ b/clang/include/clang/Sema/SemaWasm.h
@@ -29,6 +29,7 @@ class SemaWasm : public SemaBase {
                                            CallExpr *TheCall);
 
   bool BuiltinWasmRefNullExtern(CallExpr *TheCall);
+  bool BuiltinWasmRefIsNullExtern(CallExpr *TheCall);
   bool BuiltinWasmRefNullFunc(CallExpr *TheCall);
   bool BuiltinWasmTableGet(CallExpr *TheCall);
   bool BuiltinWasmTableSet(CallExpr *TheCall);
diff --git a/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp b/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
index 698f43215a1be..b7fd70e855d40 100644
--- a/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
+++ b/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
@@ -209,6 +209,11 @@ Value *CodeGenFunction::EmitWebAssemblyBuiltinExpr(unsigned BuiltinID,
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_null_extern);
     return Builder.CreateCall(Callee);
   }
+  case WebAssembly::BI__builtin_wasm_ref_is_null_extern: {
+    Value *Src = EmitScalarExpr(E->getArg(0));
+    Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_is_null_extern);
+    return Builder.CreateCall(Callee, {Src});
+  }
   case WebAssembly::BI__builtin_wasm_ref_null_func: {
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_null_func);
     return Builder.CreateCall(Callee);
diff --git a/clang/lib/Sema/SemaWasm.cpp b/clang/lib/Sema/SemaWasm.cpp
index c0fa05bc17609..4157e179c97d6 100644
--- a/clang/lib/Sema/SemaWasm.cpp
+++ b/clang/lib/Sema/SemaWasm.cpp
@@ -52,14 +52,34 @@ static bool CheckWasmBuiltinArgIsInteger(Sema &S, CallExpr *E,
 }
 
 bool SemaWasm::BuiltinWasmRefNullExtern(CallExpr *TheCall) {
-  if (TheCall->getNumArgs() != 0)
+  if (TheCall->getNumArgs() != 0) {
+    Diag(TheCall->getBeginLoc(), diag::err_typecheck_call_too_many_args)
+        << 0 /*function call*/ << /*expected*/ 0 << TheCall->getNumArgs()
+        << /*is non object*/ 0;
     return true;
-
+  }
   TheCall->setType(getASTContext().getWebAssemblyExternrefType());
 
   return false;
 }
 
+bool SemaWasm::BuiltinWasmRefIsNullExtern(CallExpr *TheCall) {
+  if (SemaRef.checkArgCount(TheCall, 1)) {
+    return true;
+  }
+
+  Expr *ArgExpr = TheCall->getArg(0);
+  if (!ArgExpr->getType().isWebAssemblyExternrefType()) {
+    SemaRef.Diag(ArgExpr->getBeginLoc(),
+                  diag::err_wasm_builtin_arg_must_be_externref_type)
+           << 1 << ArgExpr->getSourceRange();
+    return true;
+  }
+
+  return false;
+}
+
+
 bool SemaWasm::BuiltinWasmRefNullFunc(CallExpr *TheCall) {
   ASTContext &Context = getASTContext();
   if (TheCall->getNumArgs() != 0) {
@@ -224,6 +244,8 @@ bool SemaWasm::CheckWebAssemblyBuiltinFunctionCall(const TargetInfo &TI,
     return BuiltinWasmRefNullExtern(TheCall);
   case WebAssembly::BI__builtin_wasm_ref_null_func:
     return BuiltinWasmRefNullFunc(TheCall);
+  case WebAssembly::BI__builtin_wasm_ref_is_null_extern:
+    return BuiltinWasmRefIsNullExtern(TheCall);
   case WebAssembly::BI__builtin_wasm_table_get:
     return BuiltinWasmTableGet(TheCall);
   case WebAssembly::BI__builtin_wasm_table_set:
diff --git a/clang/test/CodeGen/builtins-wasm.c b/clang/test/CodeGen/builtins-wasm.c
index 263cfd3ab4c69..4a44a9a88df11 100644
--- a/clang/test/CodeGen/builtins-wasm.c
+++ b/clang/test/CodeGen/builtins-wasm.c
@@ -741,6 +741,12 @@ __externref_t externref_null() {
   // WEBASSEMBLY-NEXT: ret
 }
 
+int externref_is_null(__externref_t arg) {
+  return __builtin_wasm_ref_is_null_extern(arg);
+  // WEBASSEMBLY: tail call i32 @llvm.wasm.ref.is_null.extern(ptr addrspace(10) %arg)
+  // WEBASSEMBLY-NEXT: ret
+}
+
 void *tp (void) {
   return __builtin_thread_pointer ();
   // WEBASSEMBLY: call {{.*}} @llvm.thread.pointer()
diff --git a/clang/test/Sema/builtins-wasm.c b/clang/test/Sema/builtins-wasm.c
index beb430616233a..31e5291d3ae5e 100644
--- a/clang/test/Sema/builtins-wasm.c
+++ b/clang/test/Sema/builtins-wasm.c
@@ -7,6 +7,10 @@ static __externref_t table[0];
 typedef void (*__funcref funcref_t)();
 void test_ref_null() {
   funcref_t func = __builtin_wasm_ref_null_func(0); // expected-error {{too many arguments to function call, expected 0, have 1}}
+  __externref_t ref = __builtin_wasm_ref_null_extern(0); // expected-error {{too many arguments to function call, expected 0, have 1}}
+  __builtin_wasm_ref_is_null_extern(ref, 1); // expected-error {{too many arguments to function call, expected 1, have 2}}
+  __builtin_wasm_ref_is_null_extern(); // expected-error {{too few arguments to function call, expected 1, have 0}}
+  __builtin_wasm_ref_is_null_extern(1); // expected-error {{1st argument must be an externref}}
 }
 
 void test_table_size(__externref_t ref, void *ptr, int arr[]) {

llvmbot · 2025-05-12T17:02:42Z

@llvm/pr-subscribers-clang-codegen

Author: Hood Chatham (hoodmane)

Changes

I also fixed __builtin_wasm_ref_null_extern() to generate a diagnostic when it gets an argument. It seems like SemaRef.checkArgCount() has a bug that makes it unable to check for 0 args.

cc @sbc100 @pmatos

Full diff: https://github.com/llvm/llvm-project/pull/139580.diff

7 Files Affected:

(modified) clang/include/clang/Basic/BuiltinsWebAssembly.def (+1)
(modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (+2)
(modified) clang/include/clang/Sema/SemaWasm.h (+1)
(modified) clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp (+5)
(modified) clang/lib/Sema/SemaWasm.cpp (+24-2)
(modified) clang/test/CodeGen/builtins-wasm.c (+6)
(modified) clang/test/Sema/builtins-wasm.c (+4)

diff --git a/clang/include/clang/Basic/BuiltinsWebAssembly.def b/clang/include/clang/Basic/BuiltinsWebAssembly.def
index ab480369b3820..e2afcc08064b2 100644
--- a/clang/include/clang/Basic/BuiltinsWebAssembly.def
+++ b/clang/include/clang/Basic/BuiltinsWebAssembly.def
@@ -192,6 +192,7 @@ TARGET_BUILTIN(__builtin_wasm_replace_lane_f16x8, "V8hV8hIif", "nc", "fp16")
 // in which case the argument spec (second argument) is unused.
 
 TARGET_BUILTIN(__builtin_wasm_ref_null_extern, "i", "nct", "reference-types")
+TARGET_BUILTIN(__builtin_wasm_ref_is_null_extern, "ii", "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
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index e5a7cdc14a737..d4abc46ae58ee 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -12991,6 +12991,8 @@ def err_wasm_reftype_multidimensional_array : Error<
   "multi-dimensional arrays of WebAssembly references are not allowed">;
 def err_wasm_builtin_arg_must_be_table_type : Error <
   "%ordinal0 argument must be a WebAssembly table">;
+def err_wasm_builtin_arg_must_be_externref_type : Error <
+  "%ordinal0 argument must be an externref">;
 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 <
diff --git a/clang/include/clang/Sema/SemaWasm.h b/clang/include/clang/Sema/SemaWasm.h
index 8841fdff23035..2123e073516cb 100644
--- a/clang/include/clang/Sema/SemaWasm.h
+++ b/clang/include/clang/Sema/SemaWasm.h
@@ -29,6 +29,7 @@ class SemaWasm : public SemaBase {
                                            CallExpr *TheCall);
 
   bool BuiltinWasmRefNullExtern(CallExpr *TheCall);
+  bool BuiltinWasmRefIsNullExtern(CallExpr *TheCall);
   bool BuiltinWasmRefNullFunc(CallExpr *TheCall);
   bool BuiltinWasmTableGet(CallExpr *TheCall);
   bool BuiltinWasmTableSet(CallExpr *TheCall);
diff --git a/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp b/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
index 698f43215a1be..b7fd70e855d40 100644
--- a/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
+++ b/clang/lib/CodeGen/TargetBuiltins/WebAssembly.cpp
@@ -209,6 +209,11 @@ Value *CodeGenFunction::EmitWebAssemblyBuiltinExpr(unsigned BuiltinID,
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_null_extern);
     return Builder.CreateCall(Callee);
   }
+  case WebAssembly::BI__builtin_wasm_ref_is_null_extern: {
+    Value *Src = EmitScalarExpr(E->getArg(0));
+    Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_is_null_extern);
+    return Builder.CreateCall(Callee, {Src});
+  }
   case WebAssembly::BI__builtin_wasm_ref_null_func: {
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_ref_null_func);
     return Builder.CreateCall(Callee);
diff --git a/clang/lib/Sema/SemaWasm.cpp b/clang/lib/Sema/SemaWasm.cpp
index c0fa05bc17609..4157e179c97d6 100644
--- a/clang/lib/Sema/SemaWasm.cpp
+++ b/clang/lib/Sema/SemaWasm.cpp
@@ -52,14 +52,34 @@ static bool CheckWasmBuiltinArgIsInteger(Sema &S, CallExpr *E,
 }
 
 bool SemaWasm::BuiltinWasmRefNullExtern(CallExpr *TheCall) {
-  if (TheCall->getNumArgs() != 0)
+  if (TheCall->getNumArgs() != 0) {
+    Diag(TheCall->getBeginLoc(), diag::err_typecheck_call_too_many_args)
+        << 0 /*function call*/ << /*expected*/ 0 << TheCall->getNumArgs()
+        << /*is non object*/ 0;
     return true;
-
+  }
   TheCall->setType(getASTContext().getWebAssemblyExternrefType());
 
   return false;
 }
 
+bool SemaWasm::BuiltinWasmRefIsNullExtern(CallExpr *TheCall) {
+  if (SemaRef.checkArgCount(TheCall, 1)) {
+    return true;
+  }
+
+  Expr *ArgExpr = TheCall->getArg(0);
+  if (!ArgExpr->getType().isWebAssemblyExternrefType()) {
+    SemaRef.Diag(ArgExpr->getBeginLoc(),
+                  diag::err_wasm_builtin_arg_must_be_externref_type)
+           << 1 << ArgExpr->getSourceRange();
+    return true;
+  }
+
+  return false;
+}
+
+
 bool SemaWasm::BuiltinWasmRefNullFunc(CallExpr *TheCall) {
   ASTContext &Context = getASTContext();
   if (TheCall->getNumArgs() != 0) {
@@ -224,6 +244,8 @@ bool SemaWasm::CheckWebAssemblyBuiltinFunctionCall(const TargetInfo &TI,
     return BuiltinWasmRefNullExtern(TheCall);
   case WebAssembly::BI__builtin_wasm_ref_null_func:
     return BuiltinWasmRefNullFunc(TheCall);
+  case WebAssembly::BI__builtin_wasm_ref_is_null_extern:
+    return BuiltinWasmRefIsNullExtern(TheCall);
   case WebAssembly::BI__builtin_wasm_table_get:
     return BuiltinWasmTableGet(TheCall);
   case WebAssembly::BI__builtin_wasm_table_set:
diff --git a/clang/test/CodeGen/builtins-wasm.c b/clang/test/CodeGen/builtins-wasm.c
index 263cfd3ab4c69..4a44a9a88df11 100644
--- a/clang/test/CodeGen/builtins-wasm.c
+++ b/clang/test/CodeGen/builtins-wasm.c
@@ -741,6 +741,12 @@ __externref_t externref_null() {
   // WEBASSEMBLY-NEXT: ret
 }
 
+int externref_is_null(__externref_t arg) {
+  return __builtin_wasm_ref_is_null_extern(arg);
+  // WEBASSEMBLY: tail call i32 @llvm.wasm.ref.is_null.extern(ptr addrspace(10) %arg)
+  // WEBASSEMBLY-NEXT: ret
+}
+
 void *tp (void) {
   return __builtin_thread_pointer ();
   // WEBASSEMBLY: call {{.*}} @llvm.thread.pointer()
diff --git a/clang/test/Sema/builtins-wasm.c b/clang/test/Sema/builtins-wasm.c
index beb430616233a..31e5291d3ae5e 100644
--- a/clang/test/Sema/builtins-wasm.c
+++ b/clang/test/Sema/builtins-wasm.c
@@ -7,6 +7,10 @@ static __externref_t table[0];
 typedef void (*__funcref funcref_t)();
 void test_ref_null() {
   funcref_t func = __builtin_wasm_ref_null_func(0); // expected-error {{too many arguments to function call, expected 0, have 1}}
+  __externref_t ref = __builtin_wasm_ref_null_extern(0); // expected-error {{too many arguments to function call, expected 0, have 1}}
+  __builtin_wasm_ref_is_null_extern(ref, 1); // expected-error {{too many arguments to function call, expected 1, have 2}}
+  __builtin_wasm_ref_is_null_extern(); // expected-error {{too few arguments to function call, expected 1, have 0}}
+  __builtin_wasm_ref_is_null_extern(1); // expected-error {{1st argument must be an externref}}
 }
 
 void test_table_size(__externref_t ref, void *ptr, int arr[]) {

github-actions · 2025-05-12T17:04:43Z

✅ With the latest revision this PR passed the C/C++ code formatter.

sbc100 · 2025-05-12T17:11:19Z

(Nit: We normally spell out [WebAssembly] in PR titles)

clang/lib/Sema/SemaWasm.cpp

clang/test/CodeGen/builtins-wasm.c

sbc100 · 2025-05-12T22:07:19Z

clang/lib/Sema/SemaChecking.cpp

@@ -168,7 +168,7 @@ bool Sema::checkArgCount(CallExpr *Call, unsigned DesiredArgCount) {

  return Diag(Range.getBegin(), diag::err_typecheck_call_too_many_args)
         << 0 /*function call*/ << DesiredArgCount << ArgCount
-         << /*is non object*/ 0 << Call->getArg(1)->getSourceRange();
+         << /*is non object*/ 0 << Range;


The wasm stuff LGTM, but I don't really know anything about SemaChecking.cpp so someone else might have to review this?

It seems to have fixed a real bug in the labeling:
Before:

$ ./bin/clang -c a.c a.c:2:30: error: too many arguments to function call, expected 2, have 4 2 | __builtin_annotation(1, 2, 3, 4); | ~ ^ 1 error generated.

After:

$ ./bin/clang -c a.c a.c:2:30: error: too many arguments to function call, expected 2, have 4 2 | __builtin_annotation(1, 2, 3, 4); | ^~~~ 1 error generated.

Should I split this change into a separate PR?

That sounds like a good idea yes.

…ro arguments with one argument In this case, `Call->getArg(1)` will trap when trying to format the diagnostic. It also improves the rendering of the diagnostic some of the time: Before: ``` $ ./bin/clang -c a.c a.c:2:30: error: too many arguments to function call, expected 2, have 4 2 | __builtin_annotation(1, 2, 3, 4); | ~ ^ ``` After: ``` $ ./bin/clang -c a.c a.c:2:30: error: too many arguments to function call, expected 2, have 4 2 | __builtin_annotation(1, 2, 3, 4); | ^~~~ ``` Split from llvm#139580

shafik · 2025-05-13T02:44:43Z

(Nit: We normally spell out [WebAssembly] in PR titles)

This is useful for folks to filter.

When calling a function that expects zero arguments with one argument, `Call->getArg(1)` will trap when trying to format the diagnostic. This also seems to improve the rendering of the diagnostic some of the time. Before: ``` $ ./bin/clang -c a.c a.c:2:30: error: too many arguments to function call, expected 2, have 4 2 | __builtin_annotation(1, 2, 3, 4); | ~ ^ ``` After: ``` $ ./bin/clang -c a.c a.c:2:30: error: too many arguments to function call, expected 2, have 4 2 | __builtin_annotation(1, 2, 3, 4); | ^~~~ ``` Split from #139580. --------- Co-authored-by: Mariya Podchishchaeva <[email protected]>

tlively

WebAssembly part LGTM, too.

hoodmane · 2025-05-14T00:44:20Z

Can someone merge when ci is green?

[Wasm][Clang] Add __builtin_wasm_ref_is_null_extern

2ca282f

I also fixed __builtin_wasm_ref_null_extern() to generate a diagnostic when it gets an argument. It seems like `SemaRef.checkArgCount()` has a bug that makes it unable to check for 0 args.

llvmbot added clang Clang issues not falling into any other category backend:WebAssembly clang:frontend Language frontend issues, e.g. anything involving "Sema" clang:codegen IR generation bugs: mangling, exceptions, etc. labels May 12, 2025

Apply clang-format

cfb8e46

sbc100 reviewed May 12, 2025

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sbc100 requested review from pmatos and tlively May 12, 2025 17:16

hoodmane changed the title ~~[Wasm][Clang] Add __builtin_wasm_ref_is_null_extern~~ [WebAssembly][Clang] Add __builtin_wasm_ref_is_null_extern May 12, 2025

hoodmane mentioned this pull request May 12, 2025

[WebAssembly][Clang] Add intrinsics to make and test for an externref sentinel #139630

Open

Fix Sema::checkArgCount with 0 args

0258c51

sbc100 reviewed May 12, 2025

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hoodmane mentioned this pull request May 12, 2025

[Clang] Fix Sema::checkArgCount for 0-arg functions #139638

Merged

tlively reviewed May 13, 2025

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Merge branch 'main' into wasm-ref-is-null-extern

385deac

sbc100 approved these changes May 13, 2025

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dschuff merged commit e29b70e into llvm:main May 14, 2025
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hoodmane deleted the wasm-ref-is-null-extern branch May 14, 2025 13:47

hoodmane mentioned this pull request May 19, 2025

0.28 release pyodide/pyodide#5650

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[WebAssembly][Clang] Add __builtin_wasm_ref_is_null_extern #139580

[WebAssembly][Clang] Add __builtin_wasm_ref_is_null_extern #139580

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[WebAssembly][Clang] Add __builtin_wasm_ref_is_null_extern #139580

[WebAssembly][Clang] Add __builtin_wasm_ref_is_null_extern #139580

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