[CIR][FlattenCFG] Exceptions: support catch all only try's

Author: bcardosolopes

clang/lib/CIR/Dialect/Transforms/FlattenCFG.cpp

@@ -236,28 +236,20 @@ class CIRTryOpFlattening : public mlir::OpRewritePattern<mlir::cir::TryOp> {
         loc, mlir::cir::ExceptionInfoType::get(rewriter.getContext()));
     auto selector = rewriter.create<mlir::cir::EhSelectorOp>(loc, exception);
 
-    // TODO: direct catch all needs no dispatch?
-
     // Handle dispatch. In could in theory use a switch, but let's just
     // mimic LLVM more closely since we have no specific thing to achieve
     // doing that (might not play as well with existing optimizers either).
-    auto *dispatchBlock =
+    auto *nextDispatcher =
         rewriter.splitBlock(catchBegin, rewriter.getInsertionPoint());
     rewriter.setInsertionPointToEnd(catchBegin);
-    rewriter.create<mlir::cir::BrOp>(loc, dispatchBlock);
+    rewriter.create<mlir::cir::BrOp>(loc, nextDispatcher);
 
     // Fill in dispatcher.
-    rewriter.setInsertionPointToEnd(dispatchBlock);
-
-    // FIXME: we should have an extra block for the dispatcher, just in case
-    // there isn't one later.
-
+    rewriter.setInsertionPointToEnd(nextDispatcher);
     llvm::MutableArrayRef<mlir::Region> caseRegions = tryOp.getCatchRegions();
     mlir::ArrayAttr caseAttrList = tryOp.getCatchTypesAttr();
     unsigned caseCnt = 0;
 
-    mlir::Block *nextDispatcher = rewriter.getInsertionBlock();
-
     for (mlir::Attribute caseAttr : caseAttrList) {
       if (auto typeIdGlobal = dyn_cast<mlir::cir::GlobalViewAttr>(caseAttr)) {
         auto typeId = rewriter.create<mlir::cir::EhTypeIdOp>(
@@ -275,7 +267,8 @@ class CIRTryOpFlattening : public mlir::OpRewritePattern<mlir::cir::TryOp> {
                                              nextDispatcher);
         rewriter.setInsertionPointToEnd(nextDispatcher);
       } else if (auto catchAll = dyn_cast<mlir::cir::CatchAllAttr>(caseAttr)) {
-        assert(nextDispatcher->empty() && "expect empty dispatcher");
+        // In case the catch(...) is all we got, `nextDispatcher` shall be
+        // non-empty.
         buildAllCase(rewriter, caseRegions[caseCnt], afterTry, nextDispatcher);
         nextDispatcher = nullptr; // No more business in try/catch
       } else if (auto catchUnwind =

clang/test/CIR/Lowering/try-catch.cpp

@@ -36,7 +36,7 @@ unsigned long long tc() {
     // CIR_FLAT: ^[[BB_INT_IDX_CATCH]]:  // pred: ^[[BB_INT_IDX_SEL]]
     // CIR_FLAT:   %[[PARAM_INT_IDX:.*]] = cir.catch_param -> !cir.ptr<!s32i>
     // CIR_FLAT:   cir.const #cir.int<98>
-    // CIR_FLAT:   cir.br ^[[AFTER_TRY]]
+    // CIR_FLAT:   cir.br ^[[AFTER_TRY]] loc
     z = 98;
     idx++;
   } catch (const char* msg) {
@@ -87,3 +87,25 @@ unsigned long long tc2() {
 
   return z;
 }
+
+// CIR_FLAT: cir.func @_Z3tc3v
+unsigned long long tc3() {
+  int x = 50, y = 3;
+  unsigned long long z;
+
+  try {
+    z = division(x, y);
+  } catch (...) {
+    // CIR_FLAT:   cir.eh.selector
+    // CIR_FLAT:   cir.br ^[[CATCH_ALL:.*]] loc
+    // CIR_FLAT: ^[[CATCH_ALL]]:
+    // CIR_FLAT:   cir.catch_param -> !cir.ptr<!void>
+    // CIR_FLAT:   cir.const #cir.int<100> : !s32i
+    // CIR_FLAT:   cir.br ^[[AFTER_TRY:.*]] loc
+    // CIR_FLAT: ^[[AFTER_TRY]]:  // 2 preds
+    // CIR_FLAT:   cir.load
+    z = 100;
+  }
+
+  return z;
+}