[CIR] Add structured CatchParamOp (#165110)

Upstream, the structured CatchParamOp as a prerequisite for implementing
exception handlers

Issue #154992

Author: AmrDeveloper

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -5183,6 +5183,34 @@ def CIR_TryOp : CIR_Op<"try",[
   let hasLLVMLowering = false;
 }
 
+//===----------------------------------------------------------------------===//
+// CatchParamOp
+//===----------------------------------------------------------------------===//
+
+def CIR_CatchParamOp : CIR_Op<"catch_param", [HasParent<"cir::TryOp">]> {
+  let summary = "Represents the catch clause formal parameter";
+  let description = [{
+    The `cir.catch_param` is used to retrieves the exception object inside
+    the handler regions of `cir.try`.
+
+    This operation is used only before the CFG flatterning pass.
+
+    Example:
+
+    ```mlir
+    %exception = cir.catch_param : !cir.ptr<!void>
+    ```
+  }];
+
+  let results = (outs Optional<CIR_AnyType>:$param);
+  let assemblyFormat = [{
+    (`:` qualified(type($param))^)?
+    attr-dict
+  }];
+
+  let hasLLVMLowering = false;
+}
+
 //===----------------------------------------------------------------------===//
 // Exception related: EhInflightOp
 //===----------------------------------------------------------------------===//

clang/test/CIR/IR/catch-param.cir

@@ -0,0 +1,32 @@
+// RUN: cir-opt %s --verify-roundtrip | FileCheck %s  
+
+!s32i = !cir.int<s, 32>
+!void = !cir.void
+
+module {
+
+cir.func @catch_param_inside_catch() {
+  cir.scope {
+    cir.try {
+      cir.yield
+    } catch all {
+      %exception = cir.catch_param : !cir.ptr<!void>
+      cir.yield
+    }
+  }
+  cir.return
+}
+
+// CHECK: cir.func @catch_param_inside_catch() {
+// CHECK:   cir.scope {
+// CHECK:     cir.try {
+// CHECK:       cir.yield
+// CHECK:     } catch all {
+// CHECK:       %[[EXCEPTION:.*]] = cir.catch_param : !cir.ptr<!void> 
+// CHECK:       cir.yield
+// CHECK:     }
+// CHECK:   }
+// CHECK:   cir.return
+// CHECK: }
+
+}