[WebAssembly] Generate invokes with llvm.wasm.(re)throw

Even though `__builtin_wasm_throw`, which is lowered down to
`llvm.wasm.throw`, throws,
```cpp
try {
  __builtin_wasm_throw(0, obj);
} catch (...) {
}
```
does not generate `invoke`. This is because we have assumed the
intrinsic cannot be invoked, which doesn't make much sense. (See #128104
for the historical context)

 #128104 made `llvm.wasm.throw` intrinsic invokable in the backend. This
actually generates `invoke`s in Clang for `__builtin_wasm_throw`.

While we're at it, this also generates `invoke`s for
`__builtin_wasm_rethrow`, which is actually not used anywhere in C++
support. I haven't deleted it just in case in may have uses later. (For
example, to support rethrow functionality that carries stack trace
with exnref)

Depends on #128104 for the CI to pass.
Fixes #124710.

Author: aheejin

clang/lib/CodeGen/CGBuiltin.cpp

@@ -22493,11 +22493,11 @@ Value *CodeGenFunction::EmitWebAssemblyBuiltinExpr(unsigned BuiltinID,
     Value *Tag = EmitScalarExpr(E->getArg(0));
     Value *Obj = EmitScalarExpr(E->getArg(1));
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_throw);
-    return Builder.CreateCall(Callee, {Tag, Obj});
+    return EmitRuntimeCallOrInvoke(Callee, {Tag, Obj});
   }
   case WebAssembly::BI__builtin_wasm_rethrow: {
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_rethrow);
-    return Builder.CreateCall(Callee);
+    return EmitRuntimeCallOrInvoke(Callee);
   }
   case WebAssembly::BI__builtin_wasm_memory_atomic_wait32: {
     Value *Addr = EmitScalarExpr(E->getArg(0));

clang/test/CodeGenCXX/builtins-eh-wasm.cpp

@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -triple wasm32-unknown-unknown -fexceptions -fcxx-exceptions -target-feature +reference-types -target-feature +exception-handling -target-feature +multivalue -exception-model=wasm -emit-llvm -o - %s | FileCheck %s
+
+// Check if __builtin_wasm_throw and __builtin_wasm_rethrow are correctly
+// invoked when placed in try-catch.
+
+void throw_in_try(void *obj) {
+  try {
+    __builtin_wasm_throw(0, obj);
+  } catch (...) {
+  }
+  // CHECK: invoke void @llvm.wasm.throw(i32 0, ptr %{{.*}})
+}
+
+void rethrow_in_try() {
+  try {
+  __builtin_wasm_rethrow();
+  } catch (...) {
+  }
+  // CHECK: invoke void @llvm.wasm.rethrow()
+}