[clang] [CIR] Fix lost catch clauses on EH landing pads (PR #205638)

[via cfe-commits]

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@@ -397,17 +474,40 @@ mlir::LogicalResult ItaniumEHLowering::lowerFunc(cir::FuncOp funcOp) {
 /// \p ehTokenMap is shared across all initiates in the function so that block
 /// arguments reachable from multiple sibling initiates are registered once.
 mlir::LogicalResult ItaniumEHLowering::lowerEhInitiate(
-    cir::EhInitiateOp initiateOp, EhTokenMap &ehTokenMap,
-    SmallVectorImpl<mlir::Operation *> &deadOps) {
+    cir::EhInitiateOp initiateOp,
+    llvm::ArrayRef<cir::EhDispatchOp> reachedDispatches, bool reachesCleanup,
+    EhTokenMap &ehTokenMap, SmallVectorImpl<mlir::Operation *> &deadOps) {
   mlir::Value rootToken = initiateOp.getEhToken();
 
-  // Create the inflight_exception without a catch_type_list. The catch types
-  // will be set once we encounter the dispatch during the traversal below.
+  // The catch clauses for this landing pad come from the dispatches its
+  // exception reaches (computed read-only by the caller before any destructive
+  // lowering).  For nested try/catch the exception can reach several dispatches
+  // innermost first, so the landing pad lists their catch types in that order
+  // (matching classic CodeGen), stopping at a catch-all since nothing escapes
+  // it.  Deriving this from the original EH graph -- rather than during the
+  // destructive token-graph traversal below -- keeps it correct regardless of
+  // the order in which sibling/nested initiates are lowered.
+  mlir::ArrayAttr catchTypeList;
+  bool catchAll = false;
+  SmallVector<mlir::Attribute> typeSymbols;
+  for (cir::EhDispatchOp dispatch : reachedDispatches) {
+    if (mlir::ArrayAttr catchTypes = dispatch.getCatchTypesAttr())
+      for (mlir::Attribute attr : catchTypes)
+        typeSymbols.push_back(
+            mlir::cast<cir::GlobalViewAttr>(attr).getSymbol());
+    if (dispatch.getDefaultIsCatchAll()) {
+      catchAll = true;
+      break;
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adams381 wrote:

Added the comment and `assert(dispatch == reachedDispatches.back())` -- the catch-all is always the last reachable dispatch.

https://github.com/llvm/llvm-project/pull/205638