IPO: Add use-list-order verifier

Add a -verify-use-list-order pass, which shuffles use-list order, writes
to bitcode, reads back, and verifies that the (shuffled) order matches.

  - The utility functions live in lib/IR/UseListOrder.cpp.

  - Moved (and renamed) the command-line option to enable writing
    use-lists, so that this pass can return early if the use-list orders
    aren't being serialized.

It's not clear that this pass is the right direction long-term (perhaps
a separate tool instead?), but short-term it's a great way to test the
use-list order prototype.  I've added an XFAIL-ed testcase that I'm
hoping to get working pretty quickly.

This is part of PR5680.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213945 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/UseListOrder.h

@@ -0,0 +1,42 @@
+//===- llvm/IR/UseListOrder.h - LLVM Use List Order functions ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file has functions to modify the use-list order and to verify that it
+// doesn't change after serialization.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_USELISTORDER_H
+#define LLVM_IR_USELISTORDER_H
+
+namespace llvm {
+
+class Module;
+
+/// \brief Whether to preserve use-list ordering.
+bool shouldPreserveBitcodeUseListOrder();
+
+/// \brief Shuffle all use-lists in a module.
+///
+/// Adds \c SeedOffset to the default seed for the random number generator.
+void shuffleUseLists(Module &M, unsigned SeedOffset = 0);
+
+/// \brief Verify use-list order after serializing to bitcode.
+///
+/// \return \c true if there are no errors.
+bool verifyBitcodeUseListOrder(const Module &M);
+
+/// \brief Verify use-list order after serializing to assembly.
+///
+/// \return \c true if there are no errors.
+bool verifyAssemblyUseListOrder(const Module &M);
+
+} // end namespace llvm
+
+#endif

include/llvm/InitializePasses.h

@@ -268,6 +268,7 @@ void initializeUnifyFunctionExitNodesPass(PassRegistry&);
 void initializeUnreachableBlockElimPass(PassRegistry&);
 void initializeUnreachableMachineBlockElimPass(PassRegistry&);
 void initializeVerifierLegacyPassPass(PassRegistry&);
+void initializeVerifyUseListOrderPass(PassRegistry&);
 void initializeVirtRegMapPass(PassRegistry&);
 void initializeVirtRegRewriterPass(PassRegistry&);
 void initializeInstSimplifierPass(PassRegistry&);

include/llvm/LinkAllPasses.h

@@ -161,6 +161,7 @@ namespace {
       (void) llvm::createPartiallyInlineLibCallsPass();
       (void) llvm::createScalarizerPass();
       (void) llvm::createSeparateConstOffsetFromGEPPass();
+      (void) llvm::createVerifyUseListOrderPass();
 
       (void)new llvm::IntervalPartition();
       (void)new llvm::FindUsedTypes();

include/llvm/Transforms/IPO.h

@@ -118,6 +118,11 @@ ModulePass *createInternalizePass(ArrayRef<const char *> ExportList);
 /// createInternalizePass - Same as above, but with an empty exportList.
 ModulePass *createInternalizePass();
 
+/// \brief Verify that use-list order doesn't change after shuffling.
+///
+/// \note This is a transformation, since the use-list order changes.
+ModulePass *createVerifyUseListOrderPass();
+
 //===----------------------------------------------------------------------===//
 /// createDeadArgEliminationPass - This pass removes arguments from functions
 /// which are not used by the body of the function.

lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -22,6 +22,7 @@
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
+#include "llvm/IR/UseListOrder.h"
 #include "llvm/IR/ValueSymbolTable.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -32,12 +33,6 @@
 #include <map>
 using namespace llvm;
 
-static cl::opt<bool>
-EnablePreserveUseListOrdering("enable-bc-uselist-preserve",
-                              cl::desc("Turn on experimental support for "
-                                       "use-list order preservation."),
-                              cl::init(false), cl::Hidden);
-
 /// These are manifest constants used by the bitcode writer. They do not need to
 /// be kept in sync with the reader, but need to be consistent within this file.
 enum {
@@ -1975,7 +1970,7 @@ static void WriteModule(const Module *M, BitstreamWriter &Stream) {
   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);
 
   // Emit use-lists.
-  if (EnablePreserveUseListOrdering)
+  if (shouldPreserveBitcodeUseListOrder())
     WriteModuleUseLists(M, VE, Stream);
 
   // Emit function bodies.

lib/IR/CMakeLists.txt

@@ -39,6 +39,7 @@ add_llvm_library(LLVMCore
   Type.cpp
   TypeFinder.cpp
   Use.cpp
+  UseListOrder.cpp
   User.cpp
   Value.cpp
   ValueSymbolTable.cpp

lib/IR/UseListOrder.cpp

@@ -0,0 +1,423 @@
+//===- UseListOrder.cpp - Implement Use List Order functions --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implement use list order functions to modify use-list order and verify it
+// doesn't change after serialization.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/UseListOrder.h"
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/AsmParser/Parser.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FileUtilities.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/SourceMgr.h"
+
+#include <random>
+#include <vector>
+
+#define DEBUG_TYPE "use-list-order"
+
+using namespace llvm;
+
+static cl::opt<bool> PreserveBitcodeUseListOrder(
+    "preserve-bc-use-list-order",
+    cl::desc("Experimental support to preserve bitcode use-list order."),
+    cl::init(false), cl::Hidden);
+
+bool llvm::shouldPreserveBitcodeUseListOrder() {
+  return PreserveBitcodeUseListOrder;
+}
+
+static void shuffleValueUseLists(Value *V, std::minstd_rand0 &Gen,
+                                 DenseSet<Value *> &Seen) {
+  if (!Seen.insert(V).second)
+    return;
+
+  if (auto *C = dyn_cast<Constant>(V))
+    if (!isa<GlobalValue>(C))
+      for (Value *Op : C->operands())
+        shuffleValueUseLists(Op, Gen, Seen);
+
+  if (V->use_empty() || std::next(V->use_begin()) == V->use_end())
+    // Nothing to shuffle for 0 or 1 users.
+    return;
+
+  // Generate random numbers between 10 and 99, which will line up nicely in
+  // debug output.  We're not worried about collisons here.
+  DEBUG(dbgs() << "V = "; V->dump());
+  std::uniform_int_distribution<short> Dist(10, 99);
+  SmallDenseMap<const Use *, short, 16> Order;
+  for (const Use &U : V->uses()) {
+    auto I = Dist(Gen);
+    Order[&U] = I;
+    DEBUG(dbgs() << " - order: " << I << ", U = "; U.getUser()->dump());
+  }
+
+  DEBUG(dbgs() << " => shuffle\n");
+  V->sortUseList(
+      [&Order](const Use &L, const Use &R) { return Order[&L] < Order[&R]; });
+
+  DEBUG({
+    for (const Use &U : V->uses())
+      DEBUG(dbgs() << " - order: " << Order.lookup(&U) << ", U = ";
+            U.getUser()->dump());
+  });
+}
+
+void llvm::shuffleUseLists(Module &M, unsigned SeedOffset) {
+  DEBUG(dbgs() << "*** shuffle-use-lists ***\n");
+  std::minstd_rand0 Gen(std::minstd_rand0::default_seed + SeedOffset);
+  DenseSet<Value *> Seen;
+
+  // Shuffle the use-list of each value that would be serialized to an IR file
+  // (bitcode or assembly).
+  auto shuffle = [&](Value *V) { shuffleValueUseLists(V, Gen, Seen); };
+
+  // Globals.
+  for (GlobalVariable &G : M.globals())
+    shuffle(&G);
+  for (GlobalAlias &A : M.aliases())
+    shuffle(&A);
+  for (Function &F : M)
+    shuffle(&F);
+
+  // Constants used by globals.
+  for (GlobalVariable &G : M.globals())
+    if (G.hasInitializer())
+      shuffle(G.getInitializer());
+  for (GlobalAlias &A : M.aliases())
+    shuffle(A.getAliasee());
+  for (Function &F : M)
+    if (F.hasPrefixData())
+      shuffle(F.getPrefixData());
+
+  // Function bodies.
+  for (Function &F : M) {
+    for (Argument &A : F.args())
+      shuffle(&A);
+    for (BasicBlock &BB : F)
+      shuffle(&BB);
+    for (BasicBlock &BB : F)
+      for (Instruction &I : BB)
+        shuffle(&I);
+
+    // Constants used by instructions.
+    for (BasicBlock &BB : F)
+      for (Instruction &I : BB)
+        for (Value *Op : I.operands())
+          if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
+              isa<InlineAsm>(Op))
+            shuffle(Op);
+  }
+
+  DEBUG(dbgs() << "\n");
+}
+
+namespace {
+
+struct TempFile {
+  std::string Filename;
+  FileRemover Remover;
+  bool init(const std::string &Ext);
+  bool writeBitcode(const Module &M) const;
+  bool writeAssembly(const Module &M) const;
+  std::unique_ptr<Module> readBitcode(LLVMContext &Context) const;
+  std::unique_ptr<Module> readAssembly(LLVMContext &Context) const;
+};
+
+struct ValueMapping {
+  DenseMap<const Value *, unsigned> IDs;
+  std::vector<const Value *> Values;
+
+  /// \brief Construct a value mapping for module.
+  ///
+  /// Creates mapping from every value in \c M to an ID.  This mapping includes
+  /// un-referencable values.
+  ///
+  /// Every \a Value that gets serialized in some way should be represented
+  /// here.  The order needs to be deterministic, but it's unnecessary to match
+  /// the value-ids in the bitcode writer.
+  ///
+  /// All constants that are referenced by other values are included in the
+  /// mapping, but others -- which wouldn't be serialized -- are not.
+  ValueMapping(const Module &M);
+
+  /// \brief Map a value.
+  ///
+  /// Maps a value.  If it's a constant, maps all of its operands first.
+  void map(const Value *V);
+  unsigned lookup(const Value *V) const { return IDs.lookup(V); }
+};
+
+} // end namespace
+
+bool TempFile::init(const std::string &Ext) {
+  SmallVector<char, 64> Vector;
+  DEBUG(dbgs() << " - create-temp-file\n");
+  if (auto EC = sys::fs::createTemporaryFile("use-list-order", Ext, Vector)) {
+    DEBUG(dbgs() << "error: " << EC.message() << "\n");
+    return true;
+  }
+  assert(!Vector.empty());
+
+  Filename.assign(Vector.data(), Vector.data() + Vector.size());
+  Remover.setFile(Filename);
+  DEBUG(dbgs() << " - filename = " << Filename << "\n");
+  return false;
+}
+
+bool TempFile::writeBitcode(const Module &M) const {
+  DEBUG(dbgs() << " - write bitcode\n");
+  std::string ErrorInfo;
+  raw_fd_ostream OS(Filename.c_str(), ErrorInfo, sys::fs::F_None);
+  if (!ErrorInfo.empty()) {
+    DEBUG(dbgs() << "error: " << ErrorInfo << "\n");
+    return true;
+  }
+
+  WriteBitcodeToFile(&M, OS);
+  return false;
+}
+
+bool TempFile::writeAssembly(const Module &M) const {
+  DEBUG(dbgs() << " - write assembly\n");
+  std::string ErrorInfo;
+  raw_fd_ostream OS(Filename.c_str(), ErrorInfo, sys::fs::F_Text);
+  if (!ErrorInfo.empty()) {
+    DEBUG(dbgs() << "error: " << ErrorInfo << "\n");
+    return true;
+  }
+
+  OS << M;
+  return false;
+}
+
+std::unique_ptr<Module> TempFile::readBitcode(LLVMContext &Context) const {
+  DEBUG(dbgs() << " - read bitcode\n");
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOr =
+      MemoryBuffer::getFile(Filename);
+  if (!BufferOr) {
+    DEBUG(dbgs() << "error: " << BufferOr.getError().message() << "\n");
+    return nullptr;
+  }
+
+  std::unique_ptr<MemoryBuffer> Buffer = std::move(BufferOr.get());
+  ErrorOr<Module *> ModuleOr = parseBitcodeFile(Buffer.release(), Context);
+  if (!ModuleOr) {
+    DEBUG(dbgs() << "error: " << ModuleOr.getError().message() << "\n");
+    return nullptr;
+  }
+  return std::unique_ptr<Module>(ModuleOr.get());
+}
+
+std::unique_ptr<Module> TempFile::readAssembly(LLVMContext &Context) const {
+  DEBUG(dbgs() << " - read assembly\n");
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M(ParseAssemblyFile(Filename, Err, Context));
+  if (!M.get())
+    DEBUG(dbgs() << "error: "; Err.print("verify-use-list-order", dbgs()));
+  return M;
+}
+
+ValueMapping::ValueMapping(const Module &M) {
+  // Every value should be mapped, including things like void instructions and
+  // basic blocks that are kept out of the ValueEnumerator.
+  //
+  // The current mapping order makes it easier to debug the tables.  It happens
+  // to be similar to the ID mapping when writing ValueEnumerator, but they
+  // aren't (and needn't be) in sync.
+
+  // Globals.
+  for (const GlobalVariable &G : M.globals())
+    map(&G);
+  for (const GlobalAlias &A : M.aliases())
+    map(&A);
+  for (const Function &F : M)
+    map(&F);
+
+  // Constants used by globals.
+  for (const GlobalVariable &G : M.globals())
+    if (G.hasInitializer())
+      map(G.getInitializer());
+  for (const GlobalAlias &A : M.aliases())
+    map(A.getAliasee());
+  for (const Function &F : M)
+    if (F.hasPrefixData())
+      map(F.getPrefixData());
+
+  // Function bodies.
+  for (const Function &F : M) {
+    for (const Argument &A : F.args())
+      map(&A);
+    for (const BasicBlock &BB : F)
+      map(&BB);
+    for (const BasicBlock &BB : F)
+      for (const Instruction &I : BB)
+        map(&I);
+
+    // Constants used by instructions.
+    for (const BasicBlock &BB : F)
+      for (const Instruction &I : BB)
+        for (const Value *Op : I.operands())
+          if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
+              isa<InlineAsm>(Op))
+            map(Op);
+  }
+}
+
+void ValueMapping::map(const Value *V) {
+  if (IDs.lookup(V))
+    return;
+
+  if (auto *C = dyn_cast<Constant>(V))
+    if (!isa<GlobalValue>(C))
+      for (const Value *Op : C->operands())
+        map(Op);
+
+  Values.push_back(V);
+  IDs[V] = Values.size();
+}
+
+#ifndef NDEBUG
+static void dumpMapping(const ValueMapping &VM) {
+  dbgs() << "value-mapping (size = " << VM.Values.size() << "):\n";
+  for (unsigned I = 0, E = VM.Values.size(); I != E; ++I) {
+    dbgs() << " - id = " << I << ", value = ";
+    VM.Values[I]->dump();
+  }
+}
+
+static void debugValue(const ValueMapping &M, unsigned I, StringRef Desc) {
+  const Value *V = M.Values[I];
+  dbgs() << " - " << Desc << " value = ";
+  V->dump();
+  for (const Use &U : V->uses()) {
+    dbgs() << "   => use: op = " << U.getOperandNo()
+           << ", user-id = " << M.IDs.lookup(U.getUser()) << ", user = ";
+    U.getUser()->dump();
+  }
+}
+
+static void debugUserMismatch(const ValueMapping &L, const ValueMapping &R,
+                              unsigned I) {
+  dbgs() << " - fail: user mismatch: ID = " << I << "\n";
+  debugValue(L, I, "LHS");
+  debugValue(R, I, "RHS");
+
+  dbgs() << "\nlhs-";
+  dumpMapping(L);
+  dbgs() << "\nrhs-";
+  dumpMapping(R);
+}
+
+static void debugSizeMismatch(const ValueMapping &L, const ValueMapping &R) {
+  dbgs() << " - fail: map size: " << L.Values.size()
+         << " != " << R.Values.size() << "\n";
+  dbgs() << "\nlhs-";
+  dumpMapping(L);
+  dbgs() << "\nrhs-";
+  dumpMapping(R);
+}
+#endif
+
+static bool matches(const ValueMapping &LM, const ValueMapping &RM) {
+  DEBUG(dbgs() << "compare value maps\n");
+  if (LM.Values.size() != RM.Values.size()) {
+    DEBUG(debugSizeMismatch(LM, RM));
+    return false;
+  }
+
+  // This mapping doesn't include dangling constant users, since those don't
+  // get serialized.  However, checking if users are constant and calling
+  // isConstantUsed() on every one is very expensive.  Instead, just check if
+  // the user is mapped.
+  auto skipUnmappedUsers =
+      [&](Value::const_use_iterator &U, Value::const_use_iterator E,
+          const ValueMapping &M) {
+    while (U != E && !M.lookup(U->getUser()))
+      ++U;
+  };
+
+  // Iterate through all values, and check that both mappings have the same
+  // users.
+  for (unsigned I = 0, E = LM.Values.size(); I != E; ++I) {
+    const Value *L = LM.Values[I];
+    const Value *R = RM.Values[I];
+    auto LU = L->use_begin(), LE = L->use_end();
+    auto RU = R->use_begin(), RE = R->use_end();
+    skipUnmappedUsers(LU, LE, LM);
+    skipUnmappedUsers(RU, RE, RM);
+
+    while (LU != LE) {
+      if (RU == RE) {
+        DEBUG(debugUserMismatch(LM, RM, I));
+        return false;
+      }
+      if (LM.lookup(LU->getUser()) != RM.lookup(RU->getUser())) {
+        DEBUG(debugUserMismatch(LM, RM, I));
+        return false;
+      }
+      if (LU->getOperandNo() != RU->getOperandNo()) {
+        DEBUG(debugUserMismatch(LM, RM, I));
+        return false;
+      }
+      skipUnmappedUsers(++LU, LE, LM);
+      skipUnmappedUsers(++RU, RE, RM);
+    }
+    if (RU != RE) {
+      DEBUG(debugUserMismatch(LM, RM, I));
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool llvm::verifyBitcodeUseListOrder(const Module &M) {
+  DEBUG(dbgs() << "*** verify-use-list-order: bitcode ***\n");
+  TempFile F;
+  if (F.init("bc"))
+    return false;
+
+  if (F.writeBitcode(M))
+    return false;
+
+  LLVMContext Context;
+  std::unique_ptr<Module> OtherM = F.readBitcode(Context);
+  if (!OtherM)
+    return false;
+
+  return matches(ValueMapping(M), ValueMapping(*OtherM));
+}
+
+bool llvm::verifyAssemblyUseListOrder(const Module &M) {
+  DEBUG(dbgs() << "*** verify-use-list-order: assembly ***\n");
+  TempFile F;
+  if (F.init("ll"))
+    return false;
+
+  if (F.writeAssembly(M))
+    return false;
+
+  LLVMContext Context;
+  std::unique_ptr<Module> OtherM = F.readAssembly(Context);
+  if (!OtherM)
+    return false;
+
+  return matches(ValueMapping(M), ValueMapping(*OtherM));
+}

lib/Transforms/IPO/CMakeLists.txt

@@ -20,6 +20,7 @@ add_llvm_library(LLVMipo
   PruneEH.cpp
   StripDeadPrototypes.cpp
   StripSymbols.cpp
+  VerifyUseListOrder.cpp
   )
 
 add_dependencies(LLVMipo intrinsics_gen)

lib/Transforms/IPO/IPO.cpp

@@ -44,6 +44,7 @@ void llvm::initializeIPO(PassRegistry &Registry) {
   initializeStripDebugDeclarePass(Registry);
   initializeStripDeadDebugInfoPass(Registry);
   initializeStripNonDebugSymbolsPass(Registry);
+  initializeVerifyUseListOrderPass(Registry);
   initializeBarrierNoopPass(Registry);
 }
 

lib/Transforms/IPO/VerifyUseListOrder.cpp

@@ -0,0 +1,61 @@
+//===- VerifyUseListOrder.cpp - Use List Order Verifier ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Pass to verify use-list order doesn't change after serialization.
+//
+// Despite it being a verifier, this pass *does* transform the module, since it
+// shuffles the use-list of every value.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO.h"
+#include "llvm/IR/UseListOrder.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "use-list-order"
+
+namespace {
+class VerifyUseListOrder : public ModulePass {
+public:
+  static char ID;
+  VerifyUseListOrder();
+  bool runOnModule(Module &M) override;
+};
+} // end anonymous namespace
+
+char VerifyUseListOrder::ID = 0;
+INITIALIZE_PASS(VerifyUseListOrder, "verify-use-list-order",
+                "Verify Use List Order", false, false)
+VerifyUseListOrder::VerifyUseListOrder() : ModulePass(ID) {
+  initializeVerifyUseListOrderPass(*PassRegistry::getPassRegistry());
+}
+
+bool VerifyUseListOrder::runOnModule(Module &M) {
+  DEBUG(dbgs() << "*** verify-use-list-order ***\n");
+  if (!shouldPreserveBitcodeUseListOrder()) {
+    // Can't verify if order isn't preserved.
+    DEBUG(dbgs() << "warning: cannot verify bitcode; "
+                    "try -preserve-bc-use-list-order\n");
+    return false;
+  }
+
+  shuffleUseLists(M);
+  if (!verifyBitcodeUseListOrder(M))
+    report_fatal_error("bitcode use-list order changed");
+
+  return true;
+}
+
+ModulePass *llvm::createVerifyUseListOrderPass() {
+  return new VerifyUseListOrder;
+}

test/Bitcode/use-list-order.ll

@@ -0,0 +1,83 @@
+; RUN: opt -S < %s -preserve-bc-use-list-order -verify-use-list-order
+; XFAIL: *
+
+@a = global [4 x i1] [i1 0, i1 1, i1 0, i1 1]
+@b = alias i1* getelementptr ([4 x i1]* @a, i64 0, i64 2)
+
+define i64 @f(i64 %f) {
+entry:
+  %sum = add i64 %f, 0
+  ret i64 %sum
+}
+
+define i64 @g(i64 %g) {
+entry:
+  %sum = add i64 %g, 0
+  ret i64 %sum
+}
+
+define i64 @h(i64 %h) {
+entry:
+  %sum = add i64 %h, 0
+  ret i64 %sum
+}
+
+define i64 @i(i64 %i) {
+entry:
+  %sum = add i64 %i, 1
+  ret i64 %sum
+}
+
+define i64 @j(i64 %j) {
+entry:
+  %sum = add i64 %j, 1
+  ret i64 %sum
+}
+
+define i64 @k(i64 %k) {
+entry:
+  %sum = add i64 %k, 1
+  ret i64 %sum
+}
+
+define i64 @l(i64 %l) {
+entry:
+  %sum = add i64 %l, 1
+  ret i64 %sum
+}
+
+define i1 @loadb() {
+entry:
+  %b = load i1* @b
+  ret i1 %b
+}
+
+define i1 @loada() {
+entry:
+  %a = load i1* getelementptr ([4 x i1]* @a, i64 0, i64 2)
+  ret i1 %a
+}
+
+define i32 @f32(i32 %a, i32 %b, i32 %c, i32 %d) {
+entry:
+  br label %first
+
+second:
+  %eh = mul i32 %e, %h
+  %sum = add i32 %eh, %ef
+  br label %exit
+
+exit:
+  %product = phi i32 [%ef, %first], [%sum, %second]
+  ret i32 %product
+
+first:
+  %e = add i32 %a, 7
+  %f = add i32 %b, 7
+  %g = add i32 %c, 8
+  %h = add i32 %d, 8
+  %ef = mul i32 %e, %f
+  %gh = mul i32 %g, %h
+  %gotosecond = icmp slt i32 %gh, -9
+  br i1 %gotosecond, label %second, label %exit
+}