[llvm] [NFC] Move DroppedVariableStats to its own file. (PR #115563)

via llvm-commits llvm-commits at lists.llvm.org
Fri Nov 8 15:11:21 PST 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-ir

Author: Shubham Sandeep Rastogi (rastogishubham)

<details>
<summary>Changes</summary>

Move DroppedVariableStats code to its own file and change the class to have an extensible design so that we can use it to add dropped statistics to MIR passes and the instruction selector.

---

Patch is 34.78 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/115563.diff


7 Files Affected:

- (added) llvm/include/llvm/CodeGen/DroppedVariableStats.h (+165) 
- (modified) llvm/include/llvm/Passes/StandardInstrumentations.h (+2-78) 
- (modified) llvm/lib/CodeGen/CMakeLists.txt (+1) 
- (added) llvm/lib/CodeGen/DroppedVariableStats.cpp (+150) 
- (modified) llvm/lib/Passes/StandardInstrumentations.cpp (+2-178) 
- (modified) llvm/unittests/IR/CMakeLists.txt (+1-1) 
- (renamed) llvm/unittests/IR/DroppedVariableStatsIRTest.cpp (+28-42) 


``````````diff
diff --git a/llvm/include/llvm/CodeGen/DroppedVariableStats.h b/llvm/include/llvm/CodeGen/DroppedVariableStats.h
new file mode 100644
index 00000000000000..d90dbe8bc72446
--- /dev/null
+++ b/llvm/include/llvm/CodeGen/DroppedVariableStats.h
@@ -0,0 +1,165 @@
+///===- DroppedVariableStats.h - Opt Diagnostics -*- C++ -*----------------===//
+///
+/// Part of the LLVM Project, under the Apache License v2.0 with LLVM
+/// Exceptions. See https://llvm.org/LICENSE.txt for license information.
+/// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+///
+///===---------------------------------------------------------------------===//
+/// \file
+/// Dropped Variable Statistics for Debug Information. Reports any number
+/// of #dbg_value that get dropped due to an optimization pass.
+///
+///===---------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_DROPPEDVARIABLESTATS_H
+#define LLVM_CODEGEN_DROPPEDVARIABLESTATS_H
+
+#include "llvm/CodeGen/MachinePassManager.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PassInstrumentation.h"
+
+namespace llvm {
+
+/// A unique key that represents a #dbg_value.
+using VarID =
+    std::tuple<const DIScope *, const DIScope *, const DILocalVariable *>;
+
+/// A base class to collect and print dropped debug information variable
+/// statistics.
+class DroppedVariableStats {
+public:
+  DroppedVariableStats(bool DroppedVarStatsEnabled)
+      : DroppedVariableStatsEnabled(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 setup() {
+    DebugVariablesStack.push_back(
+        {DenseMap<const Function *, DebugVariables>()});
+    InlinedAts.push_back(
+        {DenseMap<StringRef, DenseMap<VarID, DILocation *>>()});
+    return;
+  }
+
+  void cleanup() {
+    DebugVariablesStack.pop_back();
+    InlinedAts.pop_back();
+    return;
+  }
+
+  bool getPassDroppedVariables() { return PassDroppedVariables; }
+
+protected:
+  bool PassDroppedVariables = false;
+  bool DroppedVariableStatsEnabled = false;
+
+  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;
+  /// 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(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);
+};
+
+/// 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) {}
+
+  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();
+  }
+
+  void registerCallbacks(PassInstrumentationCallbacks &PIC);
+
+private:
+  void runAfterPassFunction(StringRef PassID, const Function *F) {
+    runOnFunction(F, false);
+    calculateDroppedVarStatsOnFunction(F, PassID, F->getName().str(),
+                                       "Function");
+  }
+
+  void runAfterPassModule(StringRef PassID, const Module *M) {
+    runOnModule(M, false);
+    calculateDroppedVarStatsOnModule(M, PassID, M->getName().str(), "Module");
+  }
+  /// 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);
+  /// 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::Module. Calls runOnFunction on every Function in the Module.
+  void runOnModule(const Module *M, bool Before);
+  /// 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);
+
+  template <typename IRUnitT> static const IRUnitT *unwrapIR(Any IR) {
+    const IRUnitT **IRPtr = llvm::any_cast<const IRUnitT *>(&IR);
+    return IRPtr ? *IRPtr : nullptr;
+  }
+};
+
+} // namespace llvm
+
+#endif
diff --git a/llvm/include/llvm/Passes/StandardInstrumentations.h b/llvm/include/llvm/Passes/StandardInstrumentations.h
index 9301a12c740eec..12a34c099eaffe 100644
--- a/llvm/include/llvm/Passes/StandardInstrumentations.h
+++ b/llvm/include/llvm/Passes/StandardInstrumentations.h
@@ -19,6 +19,7 @@
 #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"
@@ -579,83 +580,6 @@ 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 {
@@ -673,7 +597,7 @@ class StandardInstrumentations {
   PrintCrashIRInstrumentation PrintCrashIR;
   IRChangedTester ChangeTester;
   VerifyInstrumentation Verify;
-  DroppedVariableStats DroppedStats;
+  DroppedVariableStatsIR DroppedStatsIR;
 
   bool VerifyEach;
 
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index 5a17944db0ae03..3eebeaaf04b3a2 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -50,6 +50,7 @@ add_llvm_component_library(LLVMCodeGen
   DeadMachineInstructionElim.cpp
   DetectDeadLanes.cpp
   DFAPacketizer.cpp
+  DroppedVariableStats.cpp
   DwarfEHPrepare.cpp
   EarlyIfConversion.cpp
   EdgeBundles.cpp
diff --git a/llvm/lib/CodeGen/DroppedVariableStats.cpp b/llvm/lib/CodeGen/DroppedVariableStats.cpp
new file mode 100644
index 00000000000000..0cdd679102a200
--- /dev/null
+++ b/llvm/lib/CodeGen/DroppedVariableStats.cpp
@@ -0,0 +1,150 @@
+///===- DroppedVariableStats.cpp - Opt Diagnostic -*- C++ -*---------------===//
+///
+/// Part of the LLVM Project, under the Apache License v2.0 with LLVM
+/// Exceptions. See https://llvm.org/LICENSE.txt for license information.
+/// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+///
+///===---------------------------------------------------------------------===//
+/// \file
+/// Dropped Variable Statistics for Debug Information. Reports any number
+/// of #dbg_value that get dropped due to an optimization pass.
+///
+///===---------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/DroppedVariableStats.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/Module.h"
+
+using namespace llvm;
+
+bool DroppedVariableStats::isScopeChildOfOrEqualTo(DIScope *Scope,
+                                                   const DIScope *DbgValScope) {
+  while (Scope != nullptr) {
+    if (VisitedScope.find(Scope) == VisitedScope.end()) {
+      VisitedScope.insert(Scope);
+      if (Scope == DbgValScope) {
+        VisitedScope.clear();
+        return true;
+      }
+      Scope = Scope->getScope();
+    } else {
+      VisitedScope.clear();
+      return false;
+    }
+  }
+  return false;
+}
+
+bool DroppedVariableStats::isInlinedAtChildOfOrEqualTo(
+    const DILocation *InlinedAt, const DILocation *DbgValInlinedAt) {
+  if (DbgValInlinedAt == InlinedAt)
+    return true;
+  if (!DbgValInlinedAt)
+    return false;
+  if (!InlinedAt)
+    return false;
+  auto *IA = InlinedAt;
+  while (IA) {
+    if (IA == DbgValInlinedAt)
+      return true;
+    IA = IA->getInlinedAt();
+  }
+  return false;
+}
+
+void DroppedVariableStatsIR::runOnFunction(const Function *F, bool Before) {
+  auto &DebugVariables = DebugVariablesStack.back()[F];
+  auto &VarIDSet = (Before ? DebugVariables.DebugVariablesBefore
+                           : DebugVariables.DebugVariablesAfter);
+  auto &InlinedAtsMap = InlinedAts.back();
+  auto FuncName = F->getName();
+  if (Before)
+    InlinedAtsMap.try_emplace(FuncName, DenseMap<VarID, DILocation *>());
+  VarIDSet = DenseSet<VarID>();
+  for (const auto &I : instructions(F)) {
+    for (DbgRecord &DR : I.getDbgRecordRange()) {
+      if (auto *Dbg = dyn_cast<DbgVariableRecord>(&DR)) {
+        auto *DbgVar = Dbg->getVariable();
+        auto DbgLoc = DR.getDebugLoc();
+        VarID Key{DbgVar->getScope(), DbgLoc->getInlinedAtScope(), DbgVar};
+        VarIDSet.insert(Key);
+        if (Before)
+          InlinedAtsMap[FuncName].try_emplace(Key, DbgLoc.getInlinedAt());
+      }
+    }
+  }
+}
+
+void DroppedVariableStatsIR::calculateDroppedVarStatsOnFunction(
+    const Function *F, StringRef PassID, std::string FuncOrModName,
+    std::string PassLevel) {
+  unsigned DroppedCount = 0;
+  StringRef FuncName = F->getName();
+  DebugVariables &DbgVariables = DebugVariablesStack.back()[F];
+  DenseSet<VarID> &DebugVariablesBeforeSet = DbgVariables.DebugVariablesBefore;
+  DenseSet<VarID> &DebugVariablesAfterSet = DbgVariables.DebugVariablesAfter;
+  DenseMap<VarID, DILocation *> &InlinedAtsMap = InlinedAts.back()[FuncName];
+  // Find an Instruction that shares the same scope as the dropped #dbg_value or
+  // has a scope that is the child of the scope of the #dbg_value, and has an
+  // inlinedAt equal to the inlinedAt of the #dbg_value or it's inlinedAt chain
+  // contains the inlinedAt of the #dbg_value, if such an Instruction is found,
+  // debug information is dropped.
+  for (VarID Var : DebugVariablesBeforeSet) {
+    if (DebugVariablesAfterSet.contains(Var))
+      continue;
+    const DIScope *DbgValScope = std::get<0>(Var);
+    for (const auto &I : instructions(F)) {
+      auto *DbgLoc = I.getDebugLoc().get();
+      if (!DbgLoc)
+        continue;
+
+      auto *Scope = DbgLoc->getScope();
+      if (isScopeChildOfOrEqualTo(Scope, DbgValScope)) {
+        if (isInlinedAtChildOfOrEqualTo(DbgLoc->getInlinedAt(),
+                                        InlinedAtsMap[Var])) {
+          // Found another instruction in the variable's scope, so there exists
+          // a break point at which the variable could be observed. Count it as
+          // dropped.
+          DroppedCount++;
+          break;
+        }
+      }
+    }
+    removeVarFromAllSets(Var, F);
+  }
+  if (DroppedCount > 0) {
+    llvm::outs() << PassLevel << ", " << PassID << ", " << DroppedCount << ", "
+                 << FuncOrModName << "\n";
+    PassDroppedVariables = true;
+  } else
+    PassDroppedVariables = false;
+}
+
+void DroppedVariableStatsIR::runOnModule(const Module *M, bool Before) {
+  for (auto &F : *M)
+    runOnFunction(&F, Before);
+}
+
+void DroppedVariableStatsIR::calculateDroppedVarStatsOnModule(
+    const Module *M, StringRef PassID, std::string FuncOrModName,
+    std::string PassLevel) {
+  for (auto &F : *M) {
+    calculateDroppedVarStatsOnFunction(&F, PassID, FuncOrModName, PassLevel);
+  }
+}
+
+void DroppedVariableStatsIR::registerCallbacks(
+    PassInstrumentationCallbacks &PIC) {
+  if (!DroppedVariableStatsEnabled)
+    return;
+
+  PIC.registerBeforeNonSkippedPassCallback(
+      [this](StringRef P, Any IR) { return runBeforePass(IR); });
+  PIC.registerAfterPassCallback(
+      [this](StringRef P, Any IR, const PreservedAnalyses &PA) {
+        return runAfterPass(P, IR);
+      });
+  PIC.registerAfterPassInvalidatedCallback(
+      [this](StringRef P, const PreservedAnalyses &PA) { return cleanup(); });
+}
diff --git a/llvm/lib/Passes/StandardInstrumentations.cpp b/llvm/lib/Passes/StandardInstrumentations.cpp
index d4866a025c1b48..c79774ec03aef1 100644
--- a/llvm/lib/Passes/StandardInstrumentations.cpp
+++ b/llvm/lib/Passes/StandardInstrumentations.cpp
@@ -2460,7 +2460,7 @@ StandardInstrumentations::StandardInstrumentations(
                        PrintChanged == ChangePrinter::ColourDiffVerbose ||
                            PrintChanged == ChangePrinter::ColourDiffQuiet),
       WebsiteChangeReporter(PrintChanged == ChangePrinter::DotCfgVerbose),
-      Verify(DebugLogging), DroppedStats(DroppedVarStats),
+      Verify(DebugLogging), DroppedStatsIR(DroppedVarStats),
       VerifyEach(VerifyEach) {}
 
 PrintCrashIRInstrumentation *PrintCrashIRInstrumentation::CrashReporter =
@@ -2521,182 +2521,6 @@ void PrintCrashIRInstrumentation::registerCallbacks(
       });
 }
 
-void DroppedVariableStats::registerCallbacks(
-    PassInstrumentationCallbacks &PIC) {
-  if (!DroppedVarStats)
-    return;
-
-  PIC.registerBeforeNonSkippedPassCallback(
-      [this](StringRef P, Any IR) { return this->runBeforePass(P, IR); });
-  PIC.registerAfterPassCallback(
-      [this](StringRef P, Any IR, const PreservedAnalyses &PA) {
-        return this->runAfterPass(P, IR, PA);
-      });
-  PIC.registerAfterPassInvalidatedCallback(
-      [this](StringRef P, const PreservedAnalyses &PA) {
-        return this->runAfterPassInvalidated(P, PA);
-      });
-}
-
-void DroppedVariableStats::runBeforePass(StringRef PassID, Any IR) {
-  DebugVariablesStack.push_back({DenseMap<const Function *, DebugVariables>()});
-  InlinedAts.push_back({DenseMap<StringRef, DenseMap<VarID, DILocation *>>()});
-  if (auto *M = unwrapIR<Module>(IR))
-    return this->runOnModule(M, true);
-  if (auto *F = unwrapIR<Function>(IR))
-    return this->runOnFunction(F, true);
-  return;
-}
-
-void DroppedVariableStats::runOnFunction(const Function *F, bool Before) {
-  auto &DebugVariables = DebugVariablesStack.back()[F];
-  auto &VarIDSet = (Before ? DebugVariables.DebugVariablesBefore
-                           : DebugVariables.DebugVariablesAfter);
-  auto &InlinedAtsMap = InlinedAts.back();
-  auto FuncName = F->getName();
-  if (Before)
-    InlinedAtsMap.try_emplace(FuncName, DenseMap<VarID, DILocation *>());
-  VarIDS...
[truncated]

``````````

</details>


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


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