[clang] [CIR] Support Try catch with handler for specific type (PR #171042)

[Amr Hesham via cfe-commits]

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@@ -344,21 +367,88 @@ CIRGenFunction::emitCXXTryStmtUnderScope(const CXXTryStmt &s) {
   return mlir::success();
 }
 
+/// Emit the structure of the dispatch block for the given catch scope.
+/// It is an invariant that the dispatch block already exists.
+static void emitCatchDispatchBlock(CIRGenFunction &cgf,
+                                   EHCatchScope &catchScope, cir::TryOp tryOp) {
+  if (EHPersonality::get(cgf).isWasmPersonality()) {
+    cgf.cgm.errorNYI("emitCatchDispatchBlock: WasmPersonality");
+    return;
+  }
+
+  if (EHPersonality::get(cgf).usesFuncletPads()) {
+    cgf.cgm.errorNYI("emitCatchDispatchBlock: usesFuncletPads");
+    return;
+  }
+
+  unsigned int numHandlers = catchScope.getNumHandlers();
+  if (numHandlers == 1 && catchScope.getHandler(0).isCatchAll()) {
+    return;
+  }
+
+  // In traditional LLVM codegen, the right handler is selected (with
+  // calls to eh_typeid_for) and the selector value is loaded. After that,
+  // blocks get connected for later codegen. In CIR, these are all
+  // implicit behaviors of cir.catch - not a lot of work to do.
+  //
+  // Test against each of the exception types we claim to catch.
+  for (unsigned i = 0;; ++i) {
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AmrDeveloper wrote:

It's a lot cleaner now :D

https://github.com/llvm/llvm-project/pull/171042