[clang] [CIR] Upstream Exception ThrowOp with subexpr (PR #161818)

[Amr Hesham via cfe-commits]

================
@@ -31,11 +31,36 @@ void CIRGenFunction::emitCXXThrowExpr(const CXXThrowExpr *e) {
     if (throwType->isObjCObjectPointerType()) {
       cgm.errorNYI("emitCXXThrowExpr ObjCObjectPointerType");
       return;
-    } else {
-      cgm.errorNYI("emitCXXThrowExpr with subExpr");
-      return;
     }
-  } else {
-    cgm.getCXXABI().emitRethrow(*this, /*isNoReturn=*/true);
+
+    cgm.getCXXABI().emitThrow(*this, e);
+    return;
   }
+
+  cgm.getCXXABI().emitRethrow(*this, /*isNoReturn=*/true);
+}
+
+void CIRGenFunction::emitAnyExprToExn(const Expr *e, Address addr) {
+  // Make sure the exception object is cleaned up if there's an
+  // exception during initialization.
+  assert(!cir::MissingFeatures::ehCleanupScope());
+
+  // __cxa_allocate_exception returns a void*;  we need to cast this
+  // to the appropriate type for the object.
+  mlir::Type ty = convertTypeForMem(e->getType());
+  Address typedAddr = addr.withElementType(builder, ty);
+
+  // From LLVM's codegen:
+  // FIXME: this isn't quite right!  If there's a final unelided call
+  // to a copy constructor, then according to [except.terminate]p1 we
+  // must call std::terminate() if that constructor throws, because
+  // technically that copy occurs after the exception expression is
+  // evaluated but before the exception is caught.  But the best way
+  // to handle that is to teach EmitAggExpr to do the final copy
+  // differently if it can't be elided.
+  emitAnyExprToMem(e, typedAddr, e->getType().getQualifiers(),
+                   /*isInitializer=*/true);
+
+  // Deactivate the cleanup block.
+  assert(!cir::MissingFeatures::ehCleanupScope());
----------------
AmrDeveloper wrote:

Without `cir::FreeExceptionOp` pushed to the stack calling Deactivate will trigger assertion `deactivating bottom of stack?`, I will either remove `deactivateCleanupBlock` from this PR or add support for FreeException after syncing the code with recent classical codegen (The other comment)

https://github.com/llvm/llvm-project/pull/161818