[clang] [WebAssembly] Add funclet bundle to thread local wrapper calls (PR #213826)

[Heejin Ahn via cfe-commits]

https://github.com/aheejin created https://github.com/llvm/llvm-project/pull/213826

When accessing a thread local variable, Clang generates a thread local wrapper function that checks if the variable has been initialized, and if it isn't, initializes it. This is a function call, so if this is within a funclet (i.e., within a `catchpad` or `cleanuppad`), it needs the funclet bundle argument, which was missing before. If it lacks a funclet argument, it will be considered invalid and removed in WinEHPrepare.

Fixes https://github.com/emscripten-core/emscripten/issues/27448.

>From 5096df7bff2dd74b3a0b6c7b10b0ecafb633235d Mon Sep 17 00:00:00 2001
From: Heejin Ahn <aheejin at gmail.com>
Date: Tue, 4 Aug 2026 03:02:52 +0000
Subject: [PATCH] [WebAssembly] Add funclet bundle to thread local wrapper
 calls

When accessing a thread local variable, Clang generates a thread local
wrapper function that checks if the variable has been initialized, and
if it isn't, initializes it. This is a function call, so if this is
within a funclet (i.e., within a `catchpad` or `cleanuppad`), it needs
the funclet bundle argument, which was missing before. If it lacks a
funclet argument, it will be considered invalid and removed in
WinEHPrepare.

Fixes https://github.com/emscripten-core/emscripten/issues/27448.
---
 clang/lib/CodeGen/ItaniumCXXABI.cpp |  3 ++-
 clang/test/CodeGenCXX/wasm-eh.cpp   | 32 +++++++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 5c5fefe32c06c..9ff0c37ca77fc 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3441,7 +3441,8 @@ LValue ItaniumCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
   llvm::Value *Val = CGF.CGM.GetAddrOfGlobalVar(VD);
   llvm::Function *Wrapper = getOrCreateThreadLocalWrapper(VD, Val);
 
-  llvm::CallInst *CallVal = CGF.Builder.CreateCall(Wrapper);
+  llvm::CallInst *CallVal =
+      CGF.Builder.CreateCall(Wrapper, {}, CGF.getBundlesForFunclet(Wrapper));
   CallVal->setCallingConv(Wrapper->getCallingConv());
 
   LValue LV;
diff --git a/clang/test/CodeGenCXX/wasm-eh.cpp b/clang/test/CodeGenCXX/wasm-eh.cpp
index f243f37ecb435..0b87107e476c7 100644
--- a/clang/test/CodeGenCXX/wasm-eh.cpp
+++ b/clang/test/CodeGenCXX/wasm-eh.cpp
@@ -41,7 +41,7 @@ void multiple_catches_wo_catch_all() {
 // CHECK-NEXT:   %[[EXN:.*]] = call ptr @llvm.wasm.get.exception(token %[[CATCHPAD]])
 // CHECK-NEXT:   store ptr %[[EXN]], ptr %exn.slot
 // CHECK-NEXT:   %[[SELECTOR:.*]] = call i32 @llvm.wasm.get.ehselector(token %[[CATCHPAD]])
-// CHECK-NEXT:   %[[TYPEID:.*]] = call i32 @llvm.eh.typeid.for.p0(ptr @_ZTIi) #7
+// CHECK-NEXT:   %[[TYPEID:.*]] = call i32 @llvm.eh.typeid.for.p0(ptr @_ZTIi) {{.*}}
 // CHECK-NEXT:   %[[MATCHES:.*]] = icmp eq i32 %[[SELECTOR]], %[[TYPEID]]
 // CHECK-NEXT:   br i1 %[[MATCHES]], label %[[CATCH_INT_BB:.*]], label %[[CATCH_FALLTHROUGH_BB:.*]]
 
@@ -58,7 +58,7 @@ void multiple_catches_wo_catch_all() {
 // CHECK-NEXT:   br label %[[TRY_CONT_BB:.*]]
 
 // CHECK: [[CATCH_FALLTHROUGH_BB]]
-// CHECK-NEXT:   %[[TYPEID:.*]] = call i32 @llvm.eh.typeid.for.p0(ptr @_ZTId) #7
+// CHECK-NEXT:   %[[TYPEID:.*]] = call i32 @llvm.eh.typeid.for.p0(ptr @_ZTId) {{.*}}
 // CHECK-NEXT:   %[[MATCHES:.*]] = icmp eq i32 %[[SELECTOR]], %[[TYPEID]]
 // CHECK-NEXT:   br i1 %[[MATCHES]], label %[[CATCH_FLOAT_BB:.*]], label %[[RETHROW_BB:.*]]
 
@@ -388,6 +388,34 @@ void noexcept_throw() noexcept {
   throw 3;
 }
 
+int get_val() { return 42; }
+thread_local int tls = get_val();
+
+// CHECK-LABEL: @_Z26tls_wrapper_within_funcletv()
+// CHECK:   %[[CATCHSWITCH:.*]] = catchswitch within none [label %[[CATCHSTART_BB:.*]]] unwind to caller
+
+// CHECK: [[CATCHSTART_BB]]:
+// CHECK-NEXT:   %[[CATCHPAD:.*]] = catchpad within %[[CATCHSWITCH]] [ptr null]
+// CHECK-NEXT:   %[[EXN:.*]] = call ptr @llvm.wasm.get.exception(token %[[CATCHPAD]])
+// CHECK-NEXT:   store ptr %[[EXN]], ptr %exn.slot
+// CHECK-NEXT:   {{.*}} call i32 @llvm.wasm.get.ehselector(token %[[CATCHPAD]])
+// CHECK-NEXT:   br label %[[CATCH_ALL_BB:.*]]
+
+// CHECK: [[CATCH_ALL_BB]]:
+// CHECK-NEXT:   %[[EXN_LOAD:.*]] = load ptr, ptr %exn.slot
+// CHECK-NEXT:   call ptr @__cxa_begin_catch(ptr %[[EXN_LOAD]]) {{.*}} [ "funclet"(token %[[CATCHPAD]]) ]
+// CHECK-NEXT:   call {{.*}} @_ZTW3tls() [ "funclet"(token %[[CATCHPAD]]) ]
+
+// Thread-local wrapper calls within a funclet should have a catchpad/cleanuppad
+// funclet bundle argument.
+int tls_wrapper_within_funclet() {
+  try {
+    throw 1;
+  } catch (...) {
+    return tls;
+  }
+}
+
 // CATCH-LABEL: define void @_Z14noexcept_throwv()
 // CHECK: %{{.*}} = cleanuppad within none []
 // CHECK-NEXT:  call void @_ZSt9terminatev()