1 files changed, 351 insertions, 0 deletions
diff --git a/lib/Transforms/Instrumentation/InstrProfiling.cpp b/lib/Transforms/Instrumentation/InstrProfiling.cpp
new file mode 100644
index 0000000..b5a491f
--- /dev/null
+++ b/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -0,0 +1,351 @@
+//===-- InstrProfiling.cpp - Frontend instrumentation based profiling -----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass lowers instrprof_increment intrinsics emitted by a frontend for
+// profiling. It also builds the data structures and initialization code needed
+// for updating execution counts and emitting the profile at runtime.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Instrumentation.h"
+
+#include "llvm/ADT/Triple.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "instrprof"
+
+namespace {
+
+class InstrProfiling : public ModulePass {
+public:
+  static char ID;
+
+  InstrProfiling() : ModulePass(ID) {}
+
+  InstrProfiling(const InstrProfOptions &Options)
+      : ModulePass(ID), Options(Options) {}
+
+  const char *getPassName() const override {
+    return "Frontend instrumentation-based coverage lowering";
+  }
+
+  bool runOnModule(Module &M) override;
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+  }
+
+private:
+  InstrProfOptions Options;
+  Module *M;
+  DenseMap<GlobalVariable *, GlobalVariable *> RegionCounters;
+  std::vector<Value *> UsedVars;
+
+  bool isMachO() const {
+    return Triple(M->getTargetTriple()).isOSBinFormatMachO();
+  }
+
+  /// Get the section name for the counter variables.
+  StringRef getCountersSection() const {
+    return isMachO() ? "__DATA,__llvm_prf_cnts" : "__llvm_prf_cnts";
+  }
+
+  /// Get the section name for the name variables.
+  StringRef getNameSection() const {
+    return isMachO() ? "__DATA,__llvm_prf_names" : "__llvm_prf_names";
+  }
+
+  /// Get the section name for the profile data variables.
+  StringRef getDataSection() const {
+    return isMachO() ? "__DATA,__llvm_prf_data" : "__llvm_prf_data";
+  }
+
+  /// Get the section name for the coverage mapping data.
+  StringRef getCoverageSection() const {
+    return isMachO() ? "__DATA,__llvm_covmap" : "__llvm_covmap";
+  }
+
+  /// Replace instrprof_increment with an increment of the appropriate value.
+  void lowerIncrement(InstrProfIncrementInst *Inc);
+
+  /// Set up the section and uses for coverage data and its references.
+  void lowerCoverageData(GlobalVariable *CoverageData);
+
+  /// Get the region counters for an increment, creating them if necessary.
+  ///
+  /// If the counter array doesn't yet exist, the profile data variables
+  /// referring to them will also be created.
+  GlobalVariable *getOrCreateRegionCounters(InstrProfIncrementInst *Inc);
+
+  /// Emit runtime registration functions for each profile data variable.
+  void emitRegistration();
+
+  /// Emit the necessary plumbing to pull in the runtime initialization.
+  void emitRuntimeHook();
+
+  /// Add uses of our data variables and runtime hook.
+  void emitUses();
+
+  /// Create a static initializer for our data, on platforms that need it.
+  void emitInitialization();
+};
+
+} // anonymous namespace
+
+char InstrProfiling::ID = 0;
+INITIALIZE_PASS(InstrProfiling, "instrprof",
+                "Frontend instrumentation-based coverage lowering.", false,
+                false)
+
+ModulePass *llvm::createInstrProfilingPass(const InstrProfOptions &Options) {
+  return new InstrProfiling(Options);
+}
+
+bool InstrProfiling::runOnModule(Module &M) {
+  bool MadeChange = false;
+
+  this->M = &M;
+  RegionCounters.clear();
+  UsedVars.clear();
+
+  for (Function &F : M)
+    for (BasicBlock &BB : F)
+      for (auto I = BB.begin(), E = BB.end(); I != E;)
+        if (auto *Inc = dyn_cast<InstrProfIncrementInst>(I++)) {
+          lowerIncrement(Inc);
+          MadeChange = true;
+        }
+  if (GlobalVariable *Coverage = M.getNamedGlobal("__llvm_coverage_mapping")) {
+    lowerCoverageData(Coverage);
+    MadeChange = true;
+  }
+  if (!MadeChange)
+    return false;
+
+  emitRegistration();
+  emitRuntimeHook();
+  emitUses();
+  emitInitialization();
+  return true;
+}
+
+void InstrProfiling::lowerIncrement(InstrProfIncrementInst *Inc) {
+  GlobalVariable *Counters = getOrCreateRegionCounters(Inc);
+
+  IRBuilder<> Builder(Inc->getParent(), *Inc);
+  uint64_t Index = Inc->getIndex()->getZExtValue();
+  llvm::Value *Addr = Builder.CreateConstInBoundsGEP2_64(Counters, 0, Index);
+  llvm::Value *Count = Builder.CreateLoad(Addr, "pgocount");
+  Count = Builder.CreateAdd(Count, Builder.getInt64(1));
+  Inc->replaceAllUsesWith(Builder.CreateStore(Count, Addr));
+  Inc->eraseFromParent();
+}
+
+void InstrProfiling::lowerCoverageData(GlobalVariable *CoverageData) {
+  CoverageData->setSection(getCoverageSection());
+  CoverageData->setAlignment(8);
+
+  Constant *Init = CoverageData->getInitializer();
+  // We're expecting { i32, i32, i32, i32, [n x { i8*, i32, i32 }], [m x i8] }
+  // for some C. If not, the frontend's given us something broken.
+  assert(Init->getNumOperands() == 6 && "bad number of fields in coverage map");
+  assert(isa<ConstantArray>(Init->getAggregateElement(4)) &&
+         "invalid function list in coverage map");
+  ConstantArray *Records = cast<ConstantArray>(Init->getAggregateElement(4));
+  for (unsigned I = 0, E = Records->getNumOperands(); I < E; ++I) {
+    Constant *Record = Records->getOperand(I);
+    Value *V = const_cast<Value *>(Record->getOperand(0))->stripPointerCasts();
+
+    assert(isa<GlobalVariable>(V) && "Missing reference to function name");
+    GlobalVariable *Name = cast<GlobalVariable>(V);
+
+    // If we have region counters for this name, we've already handled it.
+    auto It = RegionCounters.find(Name);
+    if (It != RegionCounters.end())
+      continue;
+
+    // Move the name variable to the right section.
+    Name->setSection(getNameSection());
+    Name->setAlignment(1);
+  }
+}
+
+/// Get the name of a profiling variable for a particular function.
+static std::string getVarName(InstrProfIncrementInst *Inc, StringRef VarName) {
+  auto *Arr = cast<ConstantDataArray>(Inc->getName()->getInitializer());
+  StringRef Name = Arr->isCString() ? Arr->getAsCString() : Arr->getAsString();
+  return ("__llvm_profile_" + VarName + "_" + Name).str();
+}
+
+GlobalVariable *
+InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
+  GlobalVariable *Name = Inc->getName();
+  auto It = RegionCounters.find(Name);
+  if (It != RegionCounters.end())
+    return It->second;
+
+  // Move the name variable to the right section.
+  Name->setSection(getNameSection());
+  Name->setAlignment(1);
+
+  uint64_t NumCounters = Inc->getNumCounters()->getZExtValue();
+  LLVMContext &Ctx = M->getContext();
+  ArrayType *CounterTy = ArrayType::get(Type::getInt64Ty(Ctx), NumCounters);
+
+  // Create the counters variable.
+  auto *Counters = new GlobalVariable(*M, CounterTy, false, Name->getLinkage(),
+                                      Constant::getNullValue(CounterTy),
+                                      getVarName(Inc, "counters"));
+  Counters->setVisibility(Name->getVisibility());
+  Counters->setSection(getCountersSection());
+  Counters->setAlignment(8);
+
+  RegionCounters[Inc->getName()] = Counters;
+
+  // Create data variable.
+  auto *NameArrayTy = Name->getType()->getPointerElementType();
+  auto *Int32Ty = Type::getInt32Ty(Ctx);
+  auto *Int64Ty = Type::getInt64Ty(Ctx);
+  auto *Int8PtrTy = Type::getInt8PtrTy(Ctx);
+  auto *Int64PtrTy = Type::getInt64PtrTy(Ctx);
+
+  Type *DataTypes[] = {Int32Ty, Int32Ty, Int64Ty, Int8PtrTy, Int64PtrTy};
+  auto *DataTy = StructType::get(Ctx, makeArrayRef(DataTypes));
+  Constant *DataVals[] = {
+      ConstantInt::get(Int32Ty, NameArrayTy->getArrayNumElements()),
+      ConstantInt::get(Int32Ty, NumCounters),
+      ConstantInt::get(Int64Ty, Inc->getHash()->getZExtValue()),
+      ConstantExpr::getBitCast(Name, Int8PtrTy),
+      ConstantExpr::getBitCast(Counters, Int64PtrTy)};
+  auto *Data = new GlobalVariable(*M, DataTy, true, Name->getLinkage(),
+                                  ConstantStruct::get(DataTy, DataVals),
+                                  getVarName(Inc, "data"));
+  Data->setVisibility(Name->getVisibility());
+  Data->setSection(getDataSection());
+  Data->setAlignment(8);
+
+  // Mark the data variable as used so that it isn't stripped out.
+  UsedVars.push_back(Data);
+
+  return Counters;
+}
+
+void InstrProfiling::emitRegistration() {
+  // Don't do this for Darwin.  compiler-rt uses linker magic.
+  if (Triple(M->getTargetTriple()).isOSDarwin())
+    return;
+
+  // Construct the function.
+  auto *VoidTy = Type::getVoidTy(M->getContext());
+  auto *VoidPtrTy = Type::getInt8PtrTy(M->getContext());
+  auto *RegisterFTy = FunctionType::get(VoidTy, false);
+  auto *RegisterF = Function::Create(RegisterFTy, GlobalValue::InternalLinkage,
+                                     "__llvm_profile_register_functions", M);
+  RegisterF->setUnnamedAddr(true);
+  if (Options.NoRedZone)
+    RegisterF->addFnAttr(Attribute::NoRedZone);
+
+  auto *RuntimeRegisterTy = llvm::FunctionType::get(VoidTy, VoidPtrTy, false);
+  auto *RuntimeRegisterF =
+      Function::Create(RuntimeRegisterTy, GlobalVariable::ExternalLinkage,
+                       "__llvm_profile_register_function", M);
+
+  IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", RegisterF));
+  for (Value *Data : UsedVars)
+    IRB.CreateCall(RuntimeRegisterF, IRB.CreateBitCast(Data, VoidPtrTy));
+  IRB.CreateRetVoid();
+}
+
+void InstrProfiling::emitRuntimeHook() {
+  const char *const RuntimeVarName = "__llvm_profile_runtime";
+  const char *const RuntimeUserName = "__llvm_profile_runtime_user";
+
+  // If the module's provided its own runtime, we don't need to do anything.
+  if (M->getGlobalVariable(RuntimeVarName))
+    return;
+
+  // Declare an external variable that will pull in the runtime initialization.
+  auto *Int32Ty = Type::getInt32Ty(M->getContext());
+  auto *Var =
+      new GlobalVariable(*M, Int32Ty, false, GlobalValue::ExternalLinkage,
+                         nullptr, RuntimeVarName);
+
+  // Make a function that uses it.
+  auto *User =
+      Function::Create(FunctionType::get(Int32Ty, false),
+                       GlobalValue::LinkOnceODRLinkage, RuntimeUserName, M);
+  User->addFnAttr(Attribute::NoInline);
+  if (Options.NoRedZone)
+    User->addFnAttr(Attribute::NoRedZone);
+  User->setVisibility(GlobalValue::HiddenVisibility);
+
+  IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", User));
+  auto *Load = IRB.CreateLoad(Var);
+  IRB.CreateRet(Load);
+
+  // Mark the user variable as used so that it isn't stripped out.
+  UsedVars.push_back(User);
+}
+
+void InstrProfiling::emitUses() {
+  if (UsedVars.empty())
+    return;
+
+  GlobalVariable *LLVMUsed = M->getGlobalVariable("llvm.used");
+  std::vector<Constant*> MergedVars;
+  if (LLVMUsed) {
+    // Collect the existing members of llvm.used.
+    ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
+    for (unsigned I = 0, E = Inits->getNumOperands(); I != E; ++I)
+      MergedVars.push_back(Inits->getOperand(I));
+    LLVMUsed->eraseFromParent();
+  }
+
+  Type *i8PTy = Type::getInt8PtrTy(M->getContext());
+  // Add uses for our data.
+  for (auto *Value : UsedVars)
+    MergedVars.push_back(
+        ConstantExpr::getBitCast(cast<llvm::Constant>(Value), i8PTy));
+
+  // Recreate llvm.used.
+  ArrayType *ATy = ArrayType::get(i8PTy, MergedVars.size());
+  LLVMUsed = new llvm::GlobalVariable(
+      *M, ATy, false, llvm::GlobalValue::AppendingLinkage,
+      llvm::ConstantArray::get(ATy, MergedVars), "llvm.used");
+
+  LLVMUsed->setSection("llvm.metadata");
+}
+
+void InstrProfiling::emitInitialization() {
+  Constant *RegisterF = M->getFunction("__llvm_profile_register_functions");
+  if (!RegisterF)
+    return;
+
+  // Create the initialization function.
+  auto *VoidTy = Type::getVoidTy(M->getContext());
+  auto *F =
+      Function::Create(FunctionType::get(VoidTy, false),
+                       GlobalValue::InternalLinkage, "__llvm_profile_init", M);
+  F->setUnnamedAddr(true);
+  F->addFnAttr(Attribute::NoInline);
+  if (Options.NoRedZone)
+    F->addFnAttr(Attribute::NoRedZone);
+
+  // Add the basic block and the necessary calls.
+  IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", F));
+  IRB.CreateCall(RegisterF);
+  IRB.CreateRetVoid();
+
+  appendToGlobalCtors(*M, F, 0);
+}