InstrProf: An intrinsic and lowering for instrumentation based profiling

Introduce the ``llvm.instrprof_increment`` intrinsic and the
``-instrprof`` pass. These provide the infrastructure for writing
counters for profiling, as in clang's ``-fprofile-instr-generate``.

The implementation of the instrprof pass is ported directly out of the
CodeGenPGO classes in clang, and with the followup in clang that rips
that code out to use these new intrinsics this ends up being NFC.

Doing the instrumentation this way opens some doors in terms of
improving the counter performance. For example, this will make it
simple to experiment with alternate lowering strategies, and allows us
to try handling profiling specially in some optimizations if we want
to.

Finally, this drastically simplifies the frontend and puts all of the
lowering logic in one place.

llvm-svn: 223672

docs/LangRef.rst

@@ -7492,6 +7492,50 @@ time library.
 This instrinsic does *not* empty the instruction pipeline. Modifications
 of the current function are outside the scope of the intrinsic.
 
+'``llvm.instrprof_increment``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+      declare void @llvm.instrprof_increment(i8* <name>, i64 <hash>,
+                                             i32 <num-counters>, i32 <index>)
+
+Overview:
+"""""""""
+
+The '``llvm.instrprof_increment``' intrinsic can be emitted by a
+frontend for use with instrumentation based profiling. These will be
+lowered by the ``-instrprof`` pass to generate execution counts of a
+program at runtime.
+
+Arguments:
+""""""""""
+
+The first argument is a pointer to a global variable containing the
+name of the entity being instrumented. This should generally be the
+(mangled) function name for a set of counters.
+
+The second argument is a hash value that can be used by the consumer
+of the profile data to detect changes to the instrumented source, and
+the third is the number of counters associated with ``name``. It is an
+error if ``hash`` or ``num-counters`` differ between two instances of
+``instrprof_increment`` that refer to the same name.
+
+The last argument refers to which of the counters for ``name`` should
+be incremented. It should be a value between 0 and ``num-counters``.
+
+Semantics:
+""""""""""
+
+This intrinsic represents an increment of a profiling counter. It will
+cause the ``-instrprof`` pass to generate the appropriate data
+structures and the code to increment the appropriate value, in a
+format that can be written out by a compiler runtime and consumed via
+the ``llvm-profdata`` tool.
+
 Standard C Library Intrinsics
 -----------------------------
 

include/llvm/IR/IntrinsicInst.h

@@ -322,6 +322,33 @@ namespace llvm {
     Value *getSrc() const { return const_cast<Value*>(getArgOperand(1)); }
   };
 
+  /// This represents the llvm.instrprof_increment intrinsic.
+  class InstrProfIncrementInst : public IntrinsicInst {
+  public:
+    static inline bool classof(const IntrinsicInst *I) {
+      return I->getIntrinsicID() == Intrinsic::instrprof_increment;
+    }
+    static inline bool classof(const Value *V) {
+      return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
+    }
+
+    GlobalVariable *getName() const {
+      return cast<GlobalVariable>(
+          const_cast<Value *>(getArgOperand(0))->stripPointerCasts());
+    }
+
+    ConstantInt *getHash() const {
+      return cast<ConstantInt>(const_cast<Value *>(getArgOperand(1)));
+    }
+
+    ConstantInt *getNumCounters() const {
+      return cast<ConstantInt>(const_cast<Value *>(getArgOperand(2)));
+    }
+
+    ConstantInt *getIndex() const {
+      return cast<ConstantInt>(const_cast<Value *>(getArgOperand(3)));
+    }
+  };
 }
 
 #endif

include/llvm/IR/Intrinsics.td

@@ -291,6 +291,12 @@ def int_stackprotector : Intrinsic<[], [llvm_ptr_ty, llvm_ptrptr_ty], []>;
 def int_stackprotectorcheck : Intrinsic<[], [llvm_ptrptr_ty],
                                         [IntrReadWriteArgMem]>;
 
+// A counter increment for instrumentation based profiling.
+def int_instrprof_increment : Intrinsic<[],
+                                        [llvm_ptr_ty, llvm_i64_ty,
+                                         llvm_i32_ty, llvm_i32_ty],
+                                        []>;
+
 //===------------------- Standard C Library Intrinsics --------------------===//
 //
 

include/llvm/InitializePasses.h

@@ -121,6 +121,7 @@ void initializeEarlyIfConverterPass(PassRegistry&);
 void initializeEdgeBundlesPass(PassRegistry&);
 void initializeExpandPostRAPass(PassRegistry&);
 void initializeGCOVProfilerPass(PassRegistry&);
+void initializeInstrProfilingPass(PassRegistry&);
 void initializeAddressSanitizerPass(PassRegistry&);
 void initializeAddressSanitizerModulePass(PassRegistry&);
 void initializeMemorySanitizerPass(PassRegistry&);

include/llvm/LinkAllPasses.h

@@ -78,6 +78,7 @@ namespace {
       (void) llvm::createDomOnlyViewerPass();
       (void) llvm::createDomViewerPass();
       (void) llvm::createGCOVProfilerPass();
+      (void) llvm::createInstrProfilingPass();
       (void) llvm::createFunctionInliningPass();
       (void) llvm::createAlwaysInlinerPass();
       (void) llvm::createGlobalDCEPass();

include/llvm/Transforms/Instrumentation.h

@@ -63,6 +63,18 @@ struct GCOVOptions {
 ModulePass *createGCOVProfilerPass(const GCOVOptions &Options =
                                    GCOVOptions::getDefault());
 
+/// Options for the frontend instrumentation based profiling pass.
+struct InstrProfOptions {
+  InstrProfOptions() : NoRedZone(false) {}
+
+  // Add the 'noredzone' attribute to added runtime library calls.
+  bool NoRedZone;
+};
+
+/// Insert frontend instrumentation based profiling.
+ModulePass *createInstrProfilingPass(
+    const InstrProfOptions &Options = InstrProfOptions());
+
 // Insert AddressSanitizer (address sanity checking) instrumentation
 FunctionPass *createAddressSanitizerFunctionPass();
 ModulePass *createAddressSanitizerModulePass();

lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -5570,6 +5570,8 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
     visitGCRelocate(I);
     return nullptr;
   }
+  case Intrinsic::instrprof_increment:
+    llvm_unreachable("instrprof failed to lower an increment");
   }
 }
 

lib/Transforms/Instrumentation/CMakeLists.txt

@@ -5,6 +5,7 @@ add_llvm_library(LLVMInstrumentation
   GCOVProfiling.cpp
   MemorySanitizer.cpp
   Instrumentation.cpp
+  InstrProfiling.cpp
   SanitizerCoverage.cpp
   ThreadSanitizer.cpp
   )

lib/Transforms/Instrumentation/InstrProfiling.cpp

@@ -0,0 +1,309 @@
+//===-- 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";
+  }
+
+  /// Replace instrprof_increment with an increment of the appropriate value.
+  void lowerIncrement(InstrProfIncrementInst *Inc);
+
+  /// 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 (!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();
+}
+
+/// 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);
+
+  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);
+}

lib/Transforms/Instrumentation/Instrumentation.cpp

@@ -25,6 +25,7 @@ void llvm::initializeInstrumentation(PassRegistry &Registry) {
   initializeAddressSanitizerModulePass(Registry);
   initializeBoundsCheckingPass(Registry);
   initializeGCOVProfilerPass(Registry);
+  initializeInstrProfilingPass(Registry);
   initializeMemorySanitizerPass(Registry);
   initializeThreadSanitizerPass(Registry);
   initializeSanitizerCoverageModulePass(Registry);

test/Instrumentation/InstrProfiling/no-counters.ll

@@ -0,0 +1,10 @@
+;; No instrumentation should be emitted if there are no counter increments.
+
+; RUN: opt < %s -instrprof -S | FileCheck %s
+; CHECK-NOT: @__llvm_profile_counters
+; CHECK-NOT: @__llvm_profile_data
+; CHECK-NOT: @__llvm_profile_runtime
+
+define void @foo() {
+  ret void
+}

test/Instrumentation/InstrProfiling/noruntime.ll

@@ -0,0 +1,16 @@
+;; Check that we don't emit the runtime hooks if the user provided them.
+
+; RUN: opt < %s -instrprof -S | FileCheck %s
+; CHECK-NOT: define {{.*}} @__llvm_profile_runtime_user()
+; CHECK-NOT: load i32* @__llvm_profile_runtime
+
+@__llvm_profile_runtime = global i32 0, align 4
+
+@__llvm_profile_name_foo = hidden constant [3 x i8] c"foo"
+
+define void @foo() {
+  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8]* @__llvm_profile_name_foo, i32 0, i32 0), i64 0, i32 1, i32 0)
+  ret void
+}
+
+declare void @llvm.instrprof.increment(i8*, i64, i32, i32)

test/Instrumentation/InstrProfiling/platform.ll

@@ -0,0 +1,29 @@
+;; Checks for platform specific section names and initialization code.
+
+; RUN: opt < %s -mtriple=x86_64-apple-macosx10.10.0 -instrprof -S | FileCheck %s -check-prefix=MACHO
+; RUN: opt < %s -mtriple=x86_64-unknown-linux -instrprof -S | FileCheck %s -check-prefix=ELF
+
+@__llvm_profile_name_foo = hidden constant [3 x i8] c"foo"
+; MACHO: @__llvm_profile_name_foo = hidden constant [3 x i8] c"foo", section "__DATA,__llvm_prf_names", align 1
+; ELF: @__llvm_profile_name_foo = hidden constant [3 x i8] c"foo", section "__llvm_prf_names", align 1
+
+; MACHO: @__llvm_profile_counters_foo = hidden global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
+; ELF: @__llvm_profile_counters_foo = hidden global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", align 8
+
+; MACHO: @__llvm_profile_data_foo = hidden constant {{.*}}, section "__DATA,__llvm_prf_data", align 8
+; ELF: @__llvm_profile_data_foo = hidden constant {{.*}}, section "__llvm_prf_data", align 8
+define void @foo() {
+  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8]* @__llvm_profile_name_foo, i32 0, i32 0), i64 0, i32 1, i32 0)
+  ret void
+}
+
+declare void @llvm.instrprof.increment(i8*, i64, i32, i32)
+
+;; Emit registration functions for platforms that don't find the
+;; symbols by their sections.
+
+; MACHO-NOT: define internal void @__llvm_profile_register_functions
+; ELF: define internal void @__llvm_profile_register_functions
+
+; MACHO-NOT: define internal void @__llvm_profile_init
+; ELF: define internal void @__llvm_profile_init

test/Instrumentation/InstrProfiling/profiling.ll

@@ -0,0 +1,38 @@
+; RUN: opt < %s -instrprof -S | FileCheck %s
+
+target triple = "x86_64-apple-macosx10.10.0"
+
+@__llvm_profile_name_foo = hidden constant [3 x i8] c"foo"
+; CHECK: @__llvm_profile_name_foo = hidden constant [3 x i8] c"foo", section "__DATA,__llvm_prf_names", align 1
+@__llvm_profile_name_bar = hidden constant [4 x i8] c"bar\00"
+; CHECK: @__llvm_profile_name_bar = hidden constant [4 x i8] c"bar\00", section "__DATA,__llvm_prf_names", align 1
+@baz_prof_name = hidden constant [3 x i8] c"baz"
+; CHECK: @baz_prof_name = hidden constant [3 x i8] c"baz", section "__DATA,__llvm_prf_names", align 1
+
+; CHECK: @__llvm_profile_counters_foo = hidden global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
+; CHECK: @__llvm_profile_data_foo = hidden constant {{.*}}, section "__DATA,__llvm_prf_data", align 8
+define void @foo() {
+  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8]* @__llvm_profile_name_foo, i32 0, i32 0), i64 0, i32 1, i32 0)
+  ret void
+}
+
+; CHECK: @__llvm_profile_counters_bar = hidden global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
+; CHECK: @__llvm_profile_data_bar = hidden constant {{.*}}, section "__DATA,__llvm_prf_data", align 8
+define void @bar() {
+  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([4 x i8]* @__llvm_profile_name_bar, i32 0, i32 0), i64 0, i32 1, i32 0)
+  ret void
+}
+
+; CHECK: @__llvm_profile_counters_baz = hidden global [3 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
+; CHECK: @__llvm_profile_data_baz = hidden constant {{.*}}, section "__DATA,__llvm_prf_data", align 8
+define void @baz() {
+  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8]* @baz_prof_name, i32 0, i32 0), i64 0, i32 3, i32 0)
+  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8]* @baz_prof_name, i32 0, i32 0), i64 0, i32 3, i32 1)
+  call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8]* @baz_prof_name, i32 0, i32 0), i64 0, i32 3, i32 2)
+  ret void
+}
+
+declare void @llvm.instrprof.increment(i8*, i64, i32, i32)
+
+; CHECK: @__llvm_profile_runtime = external global i32
+; CHECK: @llvm.used = appending global {{.*}} @__llvm_profile_data_foo {{.*}} @__llvm_profile_data_bar {{.*}} @__llvm_profile_data_baz {{.*}} section "llvm.metadata"