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

This reverts commit 2de7881.

Reverted due to buildbot failure:

unittests/IR/CMakeFiles/IRTests.dir/DroppedVariableStatsIRTest.cpp.o:DroppedVariableStatsIRTest.cpp:function llvm::DroppedVariableStatsIR::runAfterPass(llvm::StringRef, llvm::Any): error: undefined reference to 'llvm::DroppedVariableStatsIR::runOnModule(llvm::Module const*, bool)'

Author: rastogishubham

llvm/include/llvm/CodeGen/DroppedVariableStats.h

@@ -19,7 +19,6 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
-#include "llvm/CodeGen/DroppedVariableStats.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/DebugInfoMetadata.h"
@@ -580,6 +579,83 @@ class PrintCrashIRInstrumentation {
   static void SignalHandler(void *);
 };
 
+/// A class to collect and print dropped debug information variable statistics.
+/// After every LLVM IR pass is run, it will print how many #dbg_values were
+/// dropped due to that pass.
+class DroppedVariableStats {
+public:
+  DroppedVariableStats(bool DroppedVarStatsEnabled) {
+    if (DroppedVarStatsEnabled)
+      llvm::outs()
+          << "Pass Level, Pass Name, Num of Dropped Variables, Func or "
+             "Module Name\n";
+  };
+  // We intend this to be unique per-compilation, thus no copies.
+  DroppedVariableStats(const DroppedVariableStats &) = delete;
+  void operator=(const DroppedVariableStats &) = delete;
+
+  void registerCallbacks(PassInstrumentationCallbacks &PIC);
+  void runBeforePass(StringRef PassID, Any IR);
+  void runAfterPass(StringRef PassID, Any IR, const PreservedAnalyses &PA);
+  void runAfterPassInvalidated(StringRef PassID, const PreservedAnalyses &PA);
+  bool getPassDroppedVariables() { return PassDroppedVariables; }
+
+private:
+  bool PassDroppedVariables = false;
+  /// A unique key that represents a #dbg_value.
+  using VarID =
+      std::tuple<const DIScope *, const DIScope *, const DILocalVariable *>;
+
+  struct DebugVariables {
+    /// DenseSet of VarIDs before an optimization pass has run.
+    DenseSet<VarID> DebugVariablesBefore;
+    /// DenseSet of VarIDs after an optimization pass has run.
+    DenseSet<VarID> DebugVariablesAfter;
+  };
+
+  /// A stack of a DenseMap, that maps DebugVariables for every pass to an
+  /// llvm::Function. A stack is used because an optimization pass can call
+  /// other passes.
+  SmallVector<DenseMap<const Function *, DebugVariables>> DebugVariablesStack;
+
+  /// A DenseSet tracking whether a scope was visited before.
+  DenseSet<const DIScope *> VisitedScope;
+  /// A stack of DenseMaps, which map the name of an llvm::Function to a
+  /// DenseMap of VarIDs and their inlinedAt locations before an optimization
+  /// pass has run.
+  SmallVector<DenseMap<StringRef, DenseMap<VarID, DILocation *>>> InlinedAts;
+
+  /// 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);
+  /// Populate DebugVariablesBefore, DebugVariablesAfter, InlinedAts before or
+  /// after a pass has run to facilitate dropped variable calculation for an
+  /// llvm::Function.
+  void runOnFunction(const Function *F, bool Before);
+  /// Populate DebugVariablesBefore, DebugVariablesAfter, InlinedAts before or
+  /// after a pass has run to facilitate dropped variable calculation for an
+  /// llvm::Module. Calls runOnFunction on every Function in the Module.
+  void runOnModule(const Module *M, bool Before);
+  /// Remove a dropped #dbg_value VarID from all Sets in the
+  /// DroppedVariablesBefore stack.
+  void removeVarFromAllSets(VarID Var, const Function *F);
+  /// Return true if \p Scope is the same as \p DbgValScope or a child scope of
+  /// \p DbgValScope, return false otherwise.
+  bool isScopeChildOfOrEqualTo(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);
+};
+
 /// This class provides an interface to register all the standard pass
 /// instrumentations and manages their state (if any).
 class StandardInstrumentations {
@@ -597,7 +673,7 @@ class StandardInstrumentations {
   PrintCrashIRInstrumentation PrintCrashIR;
   IRChangedTester ChangeTester;
   VerifyInstrumentation Verify;
-  DroppedVariableStatsIR DroppedStatsIR;
+  DroppedVariableStats DroppedStats;
 
   bool VerifyEach;
 

llvm/include/llvm/Passes/StandardInstrumentations.h

@@ -50,7 +50,6 @@ add_llvm_component_library(LLVMCodeGen
   DeadMachineInstructionElim.cpp
   DetectDeadLanes.cpp
   DFAPacketizer.cpp
-  DroppedVariableStats.cpp
   DwarfEHPrepare.cpp
   EarlyIfConversion.cpp
   EdgeBundles.cpp