[clang] [CIR] Add SCF ResumeOp (PR #170042)

[Amr Hesham via cfe-commits]

https://github.com/AmrDeveloper created https://github.com/llvm/llvm-project/pull/170042

Add SCF Resume op to be used before the CFG flattening pass

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

>From 50162dd8af7931ef901951d8f2958b41ecc16ad1 Mon Sep 17 00:00:00 2001
From: Amr Hesham <amr96 at programmer.net>
Date: Sun, 30 Nov 2025 17:57:21 +0100
Subject: [PATCH] [CIR] Add SCF ResumeOp

---
 clang/include/clang/CIR/Dialect/IR/CIROps.td | 30 ++++++++++++++++++++
 clang/test/CIR/IR/try-catch.cir              | 22 ++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index 5f5fab6f12300..0a8c06861a18b 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -898,6 +898,36 @@ def CIR_ContinueOp : CIR_Op<"continue", [Terminator]> {
   let hasLLVMLowering = false;
 }
 
+//===----------------------------------------------------------------------===//
+// Resume
+//===----------------------------------------------------------------------===//
+
+def CIR_SCFResumeOp : CIR_Op<"scf.resume", [
+  ReturnLike, Terminator
+]> {
+  let summary = "Resumes execution after not catching exceptions";
+  let description = [{
+    The `cir.scf.resume` operation handles an uncaught exception scenario.
+
+    Used as the terminator of a `CatchUnwind` region of `cir.try`, where it
+    does not receive any arguments (implied from the `cir.try` scope).
+
+    This operation is used only before the CFG flatterning pass.
+
+    Examples:
+    ```mlir
+    cir.try {
+      cir.yield
+    } unwind {
+      cir.scf.resume
+    }
+    ```
+  }];
+
+  let assemblyFormat = "attr-dict";
+  let hasLLVMLowering = false;
+}
+
 //===----------------------------------------------------------------------===//
 // ScopeOp
 //===----------------------------------------------------------------------===//
diff --git a/clang/test/CIR/IR/try-catch.cir b/clang/test/CIR/IR/try-catch.cir
index 7becd0b559f5e..44263345caee3 100644
--- a/clang/test/CIR/IR/try-catch.cir
+++ b/clang/test/CIR/IR/try-catch.cir
@@ -81,4 +81,26 @@ cir.func dso_local @empty_try_block_with_catch_ist() {
 // CHECK:   cir.return
 // CHECK: }
 
+cir.func dso_local @empty_try_block_with_catch_unwind_contains_resume() {
+  cir.scope {
+    cir.try {
+      cir.yield
+    } unwind {
+      cir.scf.resume
+    }
+  }
+  cir.return
+}
+
+// CHECK: cir.func dso_local @empty_try_block_with_catch_unwind_contains_resume() {
+// CHECK:   cir.scope {
+// CHECK:     cir.try {
+// CHECK:       cir.yield
+// CHECK:     } unwind {
+// CHECK:       cir.scf.resume
+// CHECK:     }
+// CHECK:   }
+// CHECK:   cir.return
+// CHECK: }
+
 }