[llvm] [NFC] Move DroppedVariableStats to its own file and redesign it to be extensible. (PR #115563)

[Adrian Prantl via llvm-commits]

================
@@ -70,36 +83,131 @@ class DroppedVariableStats {
   /// DenseMap of VarIDs and their inlinedAt locations before an optimization
   /// pass has run.
   SmallVector<DenseMap<StringRef, DenseMap<VarID, DILocation *>>> InlinedAts;
+  /// Remove a dropped #dbg_value VarID from all Sets in the
+  /// DroppedVariablesBefore stack.
+  void removeVarFromAllSets(VarID Var, const Function *F) {
+    // Do not remove Var from the last element, it will be popped from the
+    // stack.
+    for (auto &DebugVariablesMap : llvm::drop_end(DebugVariablesStack))
+      DebugVariablesMap[F].DebugVariablesBefore.erase(Var);
+  }
+  /// Return true if \p Scope is the same as \p DbgValScope or a child scope of
+  /// \p DbgValScope, return false otherwise.
+  bool isScopeChildOfOrEqualTo(const DIScope *Scope,
+                               const DIScope *DbgValScope);
+  /// Return true if \p InlinedAt is the same as \p DbgValInlinedAt or part of
+  /// the InlinedAt chain, return false otherwise.
+  bool isInlinedAtChildOfOrEqualTo(const DILocation *InlinedAt,
+                                   const DILocation *DbgValInlinedAt);
 
-  /// Iterate over all Functions in a Module and report any dropped debug
-  /// information. Will call calculateDroppedVarStatsOnFunction on every
-  /// Function.
-  void calculateDroppedVarStatsOnModule(const Module *M, StringRef PassID,
-                                        std::string FuncOrModName,
-                                        std::string PassLevel);
-  /// Iterate over all Instructions in a Function and report any dropped debug
-  /// information.
-  void calculateDroppedVarStatsOnFunction(const Function *F, StringRef PassID,
-                                          std::string FuncOrModName,
-                                          std::string PassLevel);
+  /// Calculate the number of dropped variables in an llvm::Function or
+  /// llvm::MachineFunction and print the relevant information to stdout.
+  void calculateDroppedStatsAndPrint(DebugVariables &DbgVariables,
+                                     StringRef FuncName, StringRef PassID,
+                                     StringRef FuncOrModName,
+                                     StringRef PassLevel);
+
+  /// Check if a \p Var has been dropped or is a false positive.
+  bool checkDroppedStatus(DILocation *DbgLoc, const DIScope *Scope,
+                          const DIScope *DbgValScope,
+                          DenseMap<VarID, DILocation *> &InlinedAtsMap,
+                          VarID Var);
+  /// Run code to populate relevant data structures over an llvm::Function or
+  /// llvm::MachineFunction.
+  void run(DebugVariables &DbgVariables, StringRef FuncName, bool Before);
+  /// Populate the VarIDSet and InlinedAtMap with the relevant information
+  /// needed for before and after pass analysis to determine dropped variable
+  /// status.
+  void populateVarIDSetAndInlinedMap(
+      const DILocalVariable *DbgVar, DebugLoc DbgLoc, DenseSet<VarID> &VarIDSet,
+      DenseMap<StringRef, DenseMap<VarID, DILocation *>> &InlinedAtsMap,
+      StringRef FuncName, bool Before);
+  /// Visit every VarID in the \p DebugVariablesBeforeSet and check if it may
+  /// have been dropped by an optimization pass.
+  virtual void
+  visitEveryDebugVariable(unsigned &DroppedCount,
+                          DenseSet<VarID> &DebugVariablesBeforeSet,
+                          DenseSet<VarID> &DebugVariablesAfterSet,
+                          DenseMap<VarID, DILocation *> &InlinedAtsMap) = 0;
+  /// Visit every debug intrinsic in an llvm::Function or llvm::MachineFunction
+  /// to populate relevant data structures to determine dropped variable status.
+  virtual void visitEveryDebugIntrinsic(
+      DenseSet<VarID> &VarIDSet,
+      DenseMap<StringRef, DenseMap<VarID, DILocation *>> &InlinedAtsMap,
+      StringRef FuncName, bool Before) = 0;
+};
+
+/// A class to collect and print dropped debug information due to LLVM IR
+/// optimization passes. After every LLVM IR pass is run, it will print how many
+/// #dbg_values were dropped due to that pass.
+class DroppedVariableStatsIR : public DroppedVariableStats {
+public:
+  DroppedVariableStatsIR(bool DroppedVarStatsEnabled)
+      : llvm::DroppedVariableStats(DroppedVarStatsEnabled) {}
+
+  virtual ~DroppedVariableStatsIR() = default;
+
+  void runBeforePass(Any IR) {
+    setup();
+    if (const auto *M = unwrapIR<Module>(IR))
+      return this->runOnModule(M, true);
+    if (const auto *F = unwrapIR<Function>(IR))
+      return this->runOnFunction(F, true);
+  }
+
+  void runAfterPass(StringRef P, Any IR) {
+    if (const auto *M = unwrapIR<Module>(IR))
+      runAfterPassModule(P, M);
+    else if (const auto *F = unwrapIR<Function>(IR))
+      runAfterPassFunction(P, F);
+    return cleanup();
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adrian-prantl wrote:

cleanup();

https://github.com/llvm/llvm-project/pull/115563