[clang] [CIR] Upstream Exception with empty try block (PR #162737)

[Amr Hesham via cfe-commits]

https://github.com/AmrDeveloper created https://github.com/llvm/llvm-project/pull/162737

Upstream, the basic support for the C++ try catch statement with an empty try block

Issue https://github.com/llvm/llvm-project/issues/154992

>From a53b3e75afe6daa6b6861370457c497e7a660b37 Mon Sep 17 00:00:00 2001
From: Amr Hesham <amr96 at programmer.net>
Date: Thu, 9 Oct 2025 23:04:58 +0200
Subject: [PATCH] [CIR] Upstream Exception with empty try block

---
 clang/lib/CIR/CodeGen/CIRGenException.cpp |  8 ++++++
 clang/lib/CIR/CodeGen/CIRGenFunction.h    |  2 ++
 clang/lib/CIR/CodeGen/CIRGenStmt.cpp      |  3 ++-
 clang/test/CIR/CodeGen/try-catch.cpp      | 32 +++++++++++++++++++++++
 4 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/CIR/CodeGen/try-catch.cpp

diff --git a/clang/lib/CIR/CodeGen/CIRGenException.cpp b/clang/lib/CIR/CodeGen/CIRGenException.cpp
index 645384383711b..f9ff37bc1975c 100644
--- a/clang/lib/CIR/CodeGen/CIRGenException.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenException.cpp
@@ -64,3 +64,11 @@ void CIRGenFunction::emitAnyExprToExn(const Expr *e, Address addr) {
   // Deactivate the cleanup block.
   assert(!cir::MissingFeatures::ehCleanupScope());
 }
+
+mlir::LogicalResult CIRGenFunction::emitCXXTryStmt(const CXXTryStmt &s) {
+  if (s.getTryBlock()->body_empty())
+    return mlir::LogicalResult::success();
+
+  cgm.errorNYI("exitCXXTryStmt: CXXTryStmt with non-empty body");
+  return mlir::LogicalResult::success();
+}
diff --git a/clang/lib/CIR/CodeGen/CIRGenFunction.h b/clang/lib/CIR/CodeGen/CIRGenFunction.h
index 7a606eee4f5eb..d71de2ffde6a1 100644
--- a/clang/lib/CIR/CodeGen/CIRGenFunction.h
+++ b/clang/lib/CIR/CodeGen/CIRGenFunction.h
@@ -1297,6 +1297,8 @@ class CIRGenFunction : public CIRGenTypeCache {
 
   void emitCXXThrowExpr(const CXXThrowExpr *e);
 
+  mlir::LogicalResult emitCXXTryStmt(const clang::CXXTryStmt &s);
+
   void emitCtorPrologue(const clang::CXXConstructorDecl *ctor,
                         clang::CXXCtorType ctorType, FunctionArgList &args);
 
diff --git a/clang/lib/CIR/CodeGen/CIRGenStmt.cpp b/clang/lib/CIR/CodeGen/CIRGenStmt.cpp
index 0b8f8bfdfb046..cfd48a227ed20 100644
--- a/clang/lib/CIR/CodeGen/CIRGenStmt.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenStmt.cpp
@@ -154,6 +154,8 @@ mlir::LogicalResult CIRGenFunction::emitStmt(const Stmt *s,
     return emitWhileStmt(cast<WhileStmt>(*s));
   case Stmt::DoStmtClass:
     return emitDoStmt(cast<DoStmt>(*s));
+  case Stmt::CXXTryStmtClass:
+    return emitCXXTryStmt(cast<CXXTryStmt>(*s));
   case Stmt::CXXForRangeStmtClass:
     return emitCXXForRangeStmt(cast<CXXForRangeStmt>(*s), attr);
   case Stmt::OpenACCComputeConstructClass:
@@ -199,7 +201,6 @@ mlir::LogicalResult CIRGenFunction::emitStmt(const Stmt *s,
   case Stmt::CoroutineBodyStmtClass:
     return emitCoroutineBody(cast<CoroutineBodyStmt>(*s));
   case Stmt::CoreturnStmtClass:
-  case Stmt::CXXTryStmtClass:
   case Stmt::IndirectGotoStmtClass:
   case Stmt::OMPParallelDirectiveClass:
   case Stmt::OMPTaskwaitDirectiveClass:
diff --git a/clang/test/CIR/CodeGen/try-catch.cpp b/clang/test/CIR/CodeGen/try-catch.cpp
new file mode 100644
index 0000000000000..8f0b3c4f879dd
--- /dev/null
+++ b/clang/test/CIR/CodeGen/try-catch.cpp
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fcxx-exceptions -fexceptions -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fcxx-exceptions -fexceptions -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --input-file=%t-cir.ll %s -check-prefix=LLVM
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fcxx-exceptions -fexceptions -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
+
+void empty_try_block_with_catch_all() {
+  try {} catch (...) {}
+}
+
+// CIR: cir.func{{.*}} @_Z30empty_try_block_with_catch_allv()
+// CIR:   cir.return
+
+// LLVM: define{{.*}} void @_Z30empty_try_block_with_catch_allv()
+// LLVM:  ret void
+
+// OGCG: define{{.*}} void @_Z30empty_try_block_with_catch_allv()
+// OGCG:   ret void
+
+void empty_try_block_with_catch_with_int_exception() {
+  try {} catch (int e) {}
+}
+
+// CIR: cir.func{{.*}} @_Z45empty_try_block_with_catch_with_int_exceptionv()
+// CIR:   cir.return
+
+// LLVM: define{{.*}} void @_Z45empty_try_block_with_catch_with_int_exceptionv()
+// LLVM:  ret void
+
+// OGCG: define{{.*}} void @_Z45empty_try_block_with_catch_with_int_exceptionv()
+// OGCG:   ret void