[clang] [CIR] Introduce more cleanup infrastructure (PR #152589)

[Morris Hafner via cfe-commits]

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@@ -14,10 +14,117 @@
 #ifndef CLANG_LIB_CIR_CODEGEN_CIRGENCLEANUP_H
 #define CLANG_LIB_CIR_CODEGEN_CIRGENCLEANUP_H
 
+#include "Address.h"
 #include "EHScopeStack.h"
+#include "mlir/IR/Value.h"
 
 namespace clang::CIRGen {
 
+/// A protected scope for zero-cost EH handling.
+class EHScope {
+  class CommonBitFields {
+    friend class EHScope;
+    unsigned kind : 3;
+  };
+  enum { NumCommonBits = 3 };
+
+protected:
+  class CleanupBitFields {
+    friend class EHCleanupScope;
+    unsigned : NumCommonBits;
+
+    /// Whether this cleanup needs to be run along normal edges.
+    unsigned isNormalCleanup : 1;
+
+    /// Whether this cleanup needs to be run along exception edges.
+    unsigned isEHCleanup : 1;
+
+    /// Whether this cleanup is currently active.
+    unsigned isActive : 1;
+
+    /// Whether this cleanup is a lifetime marker
+    unsigned isLifetimeMarker : 1;
+
+    /// Whether the normal cleanup should test the activation flag.
+    unsigned testFlagInNormalCleanup : 1;
+
+    /// Whether the EH cleanup should test the activation flag.
+    unsigned testFlagInEHCleanup : 1;
+
+    /// The amount of extra storage needed by the Cleanup.
+    /// Always a multiple of the scope-stack alignment.
+    unsigned cleanupSize : 12;
+  };
+
+  union {
+    CommonBitFields commonBits;
+    CleanupBitFields cleanupBits;
+  };
+
+public:
+  enum Kind { Cleanup, Catch, Terminate, Filter };
+
+  EHScope(Kind kind) { commonBits.kind = kind; }
+
+  Kind getKind() const { return static_cast<Kind>(commonBits.kind); }
+};
+
+/// A cleanup scope which generates the cleanup blocks lazily.
+class alignas(8) EHCleanupScope : public EHScope {
----------------
mmha wrote:

Should this be `alignas(EHScopeStack::ScopeStackAlignment)`? We can get rid of that static_assert below the class declaration this way.

https://github.com/llvm/llvm-project/pull/152589