Correct dwarf unwind information in function epilogue for X86

This patch aims to provide correct dwarf unwind information in function
epilogue for X86.

It consists of two parts. The first part inserts CFI instructions that set
appropriate cfa offset and cfa register in emitEpilogue() in
X86FrameLowering. This part is X86 specific.

The second part is platform independent and ensures that:

- CFI instructions do not affect code generation
- Unwind information remains correct when a function is modified by
  different passes. This is done in a late pass by analyzing information
  about cfa offset and cfa register in BBs and inserting additional CFI
  directives where necessary.

Changed CFI instructions so that they:

- are duplicable
- are not counted as instructions when tail duplicating or tail merging
- can be compared as equal

Added CFIInstrInserter pass:

- analyzes each basic block to determine cfa offset and register valid at
  its entry and exit
- verifies that outgoing cfa offset and register of predecessor blocks match
  incoming values of their successors
- inserts additional CFI directives at basic block beginning to correct the
  rule for calculating CFA

Having CFI instructions in function epilogue can cause incorrect CFA
calculation rule for some basic blocks. This can happen if, due to basic
block reordering, or the existence of multiple epilogue blocks, some of the
blocks have wrong cfa offset and register values set by the epilogue block
above them.

CFIInstrInserter is currently run only on X86, but can be used by any target
that implements support for adding CFI instructions in epilogue.


Patch by Violeta Vukobrat.

Differential Revision: https://reviews.llvm.org/D35844

llvm-svn: 317100

7 files changed, 420 insertions, 14 deletions

diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index 40cb0c0cdf1..f7c46acc62c 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -296,6 +296,11 @@ static unsigned HashEndOfMBB(const MachineBasicBlock &MBB) {
   return HashMachineInstr(*I);
 }
 
+// Whether MI should be counted as an instruction when calculating common tail.
+static bool countsAsInstruction(const MachineInstr &MI) {
+  return !(MI.isDebugValue() || MI.isCFIInstruction());
+}
+
 /// ComputeCommonTailLength - Given two machine basic blocks, compute the number
 /// of instructions they actually have in common together at their end.  Return
 /// iterators for the first shared instruction in each block.
@@ -310,9 +315,9 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
   while (I1 != MBB1->begin() && I2 != MBB2->begin()) {
     --I1; --I2;
     // Skip debugging pseudos; necessary to avoid changing the code.
-    while (I1->isDebugValue()) {
+    while (!countsAsInstruction(*I1)) {
       if (I1==MBB1->begin()) {
-        while (I2->isDebugValue()) {
+        while (!countsAsInstruction(*I2)) {
           if (I2==MBB2->begin())
             // I1==DBG at begin; I2==DBG at begin
             return TailLen;
@@ -325,7 +330,7 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
       --I1;
     }
     // I1==first (untested) non-DBG preceding known match
-    while (I2->isDebugValue()) {
+    while (!countsAsInstruction(*I2)) {
       if (I2==MBB2->begin()) {
         ++I1;
         // I1==non-DBG, or first of DBGs not at begin; I2==DBG at begin
@@ -368,6 +373,35 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
     }
     ++I1;
   }
+
+  // Ensure that I1 and I2 do not point to a CFI_INSTRUCTION. This can happen if
+  // I1 and I2 are non-identical when compared and then one or both of them ends
+  // up pointing to a CFI instruction after being incremented. For example:
+  /*
+    BB1:
+    ...
+    INSTRUCTION_A
+    ADD32ri8  <- last common instruction
+    ...
+    BB2:
+    ...
+    INSTRUCTION_B
+    CFI_INSTRUCTION
+    ADD32ri8  <- last common instruction
+    ...
+  */
+  // When INSTRUCTION_A and INSTRUCTION_B are compared as not equal, after
+  // incrementing the iterators, I1 will point to ADD, however I2 will point to
+  // the CFI instruction. Later on, this leads to BB2 being 'hacked off' at the
+  // wrong place (in ReplaceTailWithBranchTo()) which results in losing this CFI
+  // instruction.
+  while (I1 != MBB1->end() && I1->isCFIInstruction()) {
+    ++I1;
+  }
+
+  while (I2 != MBB2->end() && I2->isCFIInstruction()) {
+    ++I2;
+  }
   return TailLen;
 }
 
@@ -454,7 +488,7 @@ static unsigned EstimateRuntime(MachineBasicBlock::iterator I,
                                 MachineBasicBlock::iterator E) {
   unsigned Time = 0;
   for (; I != E; ++I) {
-    if (I->isDebugValue())
+    if (!countsAsInstruction(*I))
       continue;
     if (I->isCall())
       Time += 10;
@@ -814,12 +848,12 @@ mergeOperations(MachineBasicBlock::iterator MBBIStartPos,
     assert(MBBI != MBBIE && "Reached BB end within common tail length!");
     (void)MBBIE;
 
-    if (MBBI->isDebugValue()) {
+    if (!countsAsInstruction(*MBBI)) {
       ++MBBI;
       continue;
     }
 
-    while ((MBBICommon != MBBIECommon) && MBBICommon->isDebugValue())
+    while ((MBBICommon != MBBIECommon) && !countsAsInstruction(*MBBICommon))
       ++MBBICommon;
 
     assert(MBBICommon != MBBIECommon &&
@@ -859,7 +893,7 @@ void BranchFolder::mergeCommonTails(unsigned commonTailIndex) {
   }
 
   for (auto &MI : *MBB) {
-    if (MI.isDebugValue())
+    if (!countsAsInstruction(MI))
       continue;
     DebugLoc DL = MI.getDebugLoc();
     for (unsigned int i = 0 ; i < NextCommonInsts.size() ; i++) {
@@ -869,7 +903,7 @@ void BranchFolder::mergeCommonTails(unsigned commonTailIndex) {
       auto &Pos = NextCommonInsts[i];
       assert(Pos != SameTails[i].getBlock()->end() &&
           "Reached BB end within common tail");
-      while (Pos->isDebugValue()) {
+      while (!countsAsInstruction(*Pos)) {
         ++Pos;
         assert(Pos != SameTails[i].getBlock()->end() &&
             "Reached BB end within common tail");
diff --git a/llvm/lib/CodeGen/CFIInstrInserter.cpp b/llvm/lib/CodeGen/CFIInstrInserter.cpp
new file mode 100644
index 00000000000..7760a3b7d2f
--- /dev/null
+++ b/llvm/lib/CodeGen/CFIInstrInserter.cpp
@@ -0,0 +1,319 @@
+//===------ CFIInstrInserter.cpp - Insert additional CFI instructions -----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file This pass verifies incoming and outgoing CFA information of basic
+/// blocks. CFA information is information about offset and register set by CFI
+/// directives, valid at the start and end of a basic block. This pass checks
+/// that outgoing information of predecessors matches incoming information of
+/// their successors. Then it checks if blocks have correct CFA calculation rule
+/// set and inserts additional CFI instruction at their beginnings if they
+/// don't. CFI instructions are inserted if basic blocks have incorrect offset
+/// or register set by previous blocks, as a result of a non-linear layout of
+/// blocks in a function.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Target/TargetFrameLowering.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+using namespace llvm;
+
+namespace {
+class CFIInstrInserter : public MachineFunctionPass {
+ public:
+  static char ID;
+
+  CFIInstrInserter() : MachineFunctionPass(ID) {
+    initializeCFIInstrInserterPass(*PassRegistry::getPassRegistry());
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesAll();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override {
+
+    if (!MF.getMMI().hasDebugInfo() &&
+        !MF.getFunction()->needsUnwindTableEntry())
+      return false;
+
+    MBBVector.resize(MF.getNumBlockIDs());
+    calculateCFAInfo(MF);
+#ifndef NDEBUG
+    unsigned ErrorNum = verify(MF);
+    if (ErrorNum)
+      report_fatal_error("Found " + Twine(ErrorNum) +
+                         " in/out CFI information errors.");
+#endif
+    bool insertedCFI = insertCFIInstrs(MF);
+    MBBVector.clear();
+    return insertedCFI;
+  }
+
+ private:
+  struct MBBCFAInfo {
+    MachineBasicBlock *MBB;
+    /// Value of cfa offset valid at basic block entry.
+    int IncomingCFAOffset = -1;
+    /// Value of cfa offset valid at basic block exit.
+    int OutgoingCFAOffset = -1;
+    /// Value of cfa register valid at basic block entry.
+    unsigned IncomingCFARegister = 0;
+    /// Value of cfa register valid at basic block exit.
+    unsigned OutgoingCFARegister = 0;
+    /// If in/out cfa offset and register values for this block have already
+    /// been set or not.
+    bool Processed = false;
+  };
+
+  /// Contains cfa offset and register values valid at entry and exit of basic
+  /// blocks.
+  SmallVector<struct MBBCFAInfo, 4> MBBVector;
+
+  /// Calculate cfa offset and register values valid at entry and exit for all
+  /// basic blocks in a function.
+  void calculateCFAInfo(MachineFunction &MF);
+  /// Calculate cfa offset and register values valid at basic block exit by
+  /// checking the block for CFI instructions. Block's incoming CFA info remains
+  /// the same.
+  void calculateOutgoingCFAInfo(struct MBBCFAInfo &MBBInfo);
+  /// Update in/out cfa offset and register values for successors of the basic
+  /// block.
+  void updateSuccCFAInfo(struct MBBCFAInfo &MBBInfo);
+
+  /// Check if incoming CFA information of a basic block matches outgoing CFA
+  /// information of the previous block. If it doesn't, insert CFI instruction
+  /// at the beginning of the block that corrects the CFA calculation rule for
+  /// that block.
+  bool insertCFIInstrs(MachineFunction &MF);
+  /// Return the cfa offset value that should be set at the beginning of a MBB
+  /// if needed. The negated value is needed when creating CFI instructions that
+  /// set absolute offset.
+  int getCorrectCFAOffset(MachineBasicBlock *MBB) {
+    return -MBBVector[MBB->getNumber()].IncomingCFAOffset;
+  }
+
+  void report(const char *msg, MachineBasicBlock &MBB);
+  /// Go through each MBB in a function and check that outgoing offset and
+  /// register of its predecessors match incoming offset and register of that
+  /// MBB, as well as that incoming offset and register of its successors match
+  /// outgoing offset and register of the MBB.
+  unsigned verify(MachineFunction &MF);
+};
+}
+
+char CFIInstrInserter::ID = 0;
+INITIALIZE_PASS(CFIInstrInserter, "cfi-instr-inserter",
+                "Check CFA info and insert CFI instructions if needed", false,
+                false)
+FunctionPass *llvm::createCFIInstrInserter() { return new CFIInstrInserter(); }
+
+void CFIInstrInserter::calculateCFAInfo(MachineFunction &MF) {
+  // Initial CFA offset value i.e. the one valid at the beginning of the
+  // function.
+  int InitialOffset =
+      MF.getSubtarget().getFrameLowering()->getInitialCFAOffset(MF);
+  // Initial CFA register value i.e. the one valid at the beginning of the
+  // function.
+  unsigned InitialRegister =
+      MF.getSubtarget().getFrameLowering()->getInitialCFARegister(MF);
+
+  // Initialize MBBMap.
+  for (MachineBasicBlock &MBB : MF) {
+    struct MBBCFAInfo MBBInfo;
+    MBBInfo.MBB = &MBB;
+    MBBInfo.IncomingCFAOffset = InitialOffset;
+    MBBInfo.OutgoingCFAOffset = InitialOffset;
+    MBBInfo.IncomingCFARegister = InitialRegister;
+    MBBInfo.OutgoingCFARegister = InitialRegister;
+    MBBVector[MBB.getNumber()] = MBBInfo;
+  }
+
+  // Set in/out cfa info for all blocks in the function. This traversal is based
+  // on the assumption that the first block in the function is the entry block
+  // i.e. that it has initial cfa offset and register values as incoming CFA
+  // information.
+  for (MachineBasicBlock &MBB : MF) {
+    if (MBBVector[MBB.getNumber()].Processed) continue;
+    calculateOutgoingCFAInfo(MBBVector[MBB.getNumber()]);
+    updateSuccCFAInfo(MBBVector[MBB.getNumber()]);
+  }
+}
+
+void CFIInstrInserter::calculateOutgoingCFAInfo(struct MBBCFAInfo &MBBInfo) {
+  // Outgoing cfa offset set by the block.
+  int SetOffset = MBBInfo.IncomingCFAOffset;
+  // Outgoing cfa register set by the block.
+  unsigned SetRegister = MBBInfo.IncomingCFARegister;
+  const std::vector<MCCFIInstruction> &Instrs =
+      MBBInfo.MBB->getParent()->getFrameInstructions();
+
+  // Determine cfa offset and register set by the block.
+  for (MachineInstr &MI :
+       make_range(MBBInfo.MBB->instr_begin(), MBBInfo.MBB->instr_end())) {
+    if (MI.isCFIInstruction()) {
+      unsigned CFIIndex = MI.getOperand(0).getCFIIndex();
+      const MCCFIInstruction &CFI = Instrs[CFIIndex];
+      if (CFI.getOperation() == MCCFIInstruction::OpDefCfaRegister) {
+        SetRegister = CFI.getRegister();
+      } else if (CFI.getOperation() == MCCFIInstruction::OpDefCfaOffset) {
+        SetOffset = CFI.getOffset();
+      } else if (CFI.getOperation() == MCCFIInstruction::OpAdjustCfaOffset) {
+        SetOffset += CFI.getOffset();
+      } else if (CFI.getOperation() == MCCFIInstruction::OpDefCfa) {
+        SetRegister = CFI.getRegister();
+        SetOffset = CFI.getOffset();
+      }
+    }
+  }
+
+  MBBInfo.Processed = true;
+
+  // Update outgoing CFA info.
+  MBBInfo.OutgoingCFAOffset = SetOffset;
+  MBBInfo.OutgoingCFARegister = SetRegister;
+}
+
+void CFIInstrInserter::updateSuccCFAInfo(struct MBBCFAInfo &MBBInfo) {
+
+  for (MachineBasicBlock *Succ : MBBInfo.MBB->successors()) {
+    struct MBBCFAInfo &SuccInfo = MBBVector[Succ->getNumber()];
+    if (SuccInfo.Processed) continue;
+    SuccInfo.IncomingCFAOffset = MBBInfo.OutgoingCFAOffset;
+    SuccInfo.IncomingCFARegister = MBBInfo.OutgoingCFARegister;
+    calculateOutgoingCFAInfo(SuccInfo);
+    updateSuccCFAInfo(SuccInfo);
+  }
+}
+
+bool CFIInstrInserter::insertCFIInstrs(MachineFunction &MF) {
+
+  const struct MBBCFAInfo *PrevMBBInfo = &MBBVector[MF.front().getNumber()];
+  const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
+  bool InsertedCFIInstr = false;
+
+  for (MachineBasicBlock &MBB : MF) {
+    // Skip the first MBB in a function
+    if (MBB.getNumber() == MF.front().getNumber()) continue;
+
+    const struct MBBCFAInfo& MBBInfo = MBBVector[MBB.getNumber()];
+    auto MBBI = MBBInfo.MBB->begin();
+    DebugLoc DL = MBBInfo.MBB->findDebugLoc(MBBI);
+
+    if (PrevMBBInfo->OutgoingCFAOffset != MBBInfo.IncomingCFAOffset) {
+      // If both outgoing offset and register of a previous block don't match
+      // incoming offset and register of this block, add a def_cfa instruction
+      // with the correct offset and register for this block.
+      if (PrevMBBInfo->OutgoingCFARegister != MBBInfo.IncomingCFARegister) {
+        unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createDefCfa(
+            nullptr, MBBInfo.IncomingCFARegister, getCorrectCFAOffset(&MBB)));
+        BuildMI(*MBBInfo.MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+            .addCFIIndex(CFIIndex);
+        // If outgoing offset of a previous block doesn't match incoming offset
+        // of this block, add a def_cfa_offset instruction with the correct
+        // offset for this block.
+      } else {
+        unsigned CFIIndex =
+            MF.addFrameInst(MCCFIInstruction::createDefCfaOffset(
+                nullptr, getCorrectCFAOffset(&MBB)));
+        BuildMI(*MBBInfo.MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+            .addCFIIndex(CFIIndex);
+      }
+      InsertedCFIInstr = true;
+      // If outgoing register of a previous block doesn't match incoming
+      // register of this block, add a def_cfa_register instruction with the
+      // correct register for this block.
+    } else if (PrevMBBInfo->OutgoingCFARegister != MBBInfo.IncomingCFARegister) {
+      unsigned CFIIndex =
+          MF.addFrameInst(MCCFIInstruction::createDefCfaRegister(
+              nullptr, MBBInfo.IncomingCFARegister));
+      BuildMI(*MBBInfo.MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+          .addCFIIndex(CFIIndex);
+      InsertedCFIInstr = true;
+    }
+    PrevMBBInfo = &MBBInfo;
+  }
+  return InsertedCFIInstr;
+}
+
+void CFIInstrInserter::report(const char *msg, MachineBasicBlock &MBB) {
+  errs() << '\n';
+  errs() << "*** " << msg << " ***\n"
+         << "- function:    " << MBB.getParent()->getName() << "\n";
+  errs() << "- basic block: BB#" << MBB.getNumber() << ' ' << MBB.getName()
+         << " (" << (const void *)&MBB << ')';
+  errs() << '\n';
+}
+
+unsigned CFIInstrInserter::verify(MachineFunction &MF) {
+  unsigned ErrorNum = 0;
+  for (MachineBasicBlock &CurrMBB : MF) {
+    const struct MBBCFAInfo& CurrMBBInfo = MBBVector[CurrMBB.getNumber()];
+    for (MachineBasicBlock *Pred : CurrMBB.predecessors()) {
+      const struct MBBCFAInfo& PredMBBInfo = MBBVector[Pred->getNumber()];
+      // Check that outgoing offset values of predecessors match the incoming
+      // offset value of CurrMBB
+      if (PredMBBInfo.OutgoingCFAOffset != CurrMBBInfo.IncomingCFAOffset) {
+        report("The outgoing offset of a predecessor is inconsistent.",
+               CurrMBB);
+        errs() << "Predecessor BB#" << Pred->getNumber()
+               << " has outgoing offset (" << PredMBBInfo.OutgoingCFAOffset
+               << "), while BB#" << CurrMBB.getNumber()
+               << " has incoming offset (" << CurrMBBInfo.IncomingCFAOffset
+               << ").\n";
+        ErrorNum++;
+      }
+      // Check that outgoing register values of predecessors match the incoming
+      // register value of CurrMBB
+      if (PredMBBInfo.OutgoingCFARegister != CurrMBBInfo.IncomingCFARegister) {
+        report("The outgoing register of a predecessor is inconsistent.",
+               CurrMBB);
+        errs() << "Predecessor BB#" << Pred->getNumber()
+               << " has outgoing register (" << PredMBBInfo.OutgoingCFARegister
+               << "), while BB#" << CurrMBB.getNumber()
+               << " has incoming register (" << CurrMBBInfo.IncomingCFARegister
+               << ").\n";
+        ErrorNum++;
+      }
+    }
+
+    for (MachineBasicBlock *Succ : CurrMBB.successors()) {
+      const struct MBBCFAInfo& SuccMBBInfo = MBBVector[Succ->getNumber()];
+      // Check that incoming offset values of successors match the outgoing
+      // offset value of CurrMBB
+      if (SuccMBBInfo.IncomingCFAOffset != CurrMBBInfo.OutgoingCFAOffset) {
+        report("The incoming offset of a successor is inconsistent.", CurrMBB);
+        errs() << "Successor BB#" << Succ->getNumber()
+               << " has incoming offset (" << SuccMBBInfo.IncomingCFAOffset
+               << "), while BB#" << CurrMBB.getNumber()
+               << " has outgoing offset (" << CurrMBBInfo.OutgoingCFAOffset
+               << ").\n";
+        ErrorNum++;
+      }
+      // Check that incoming register values of successors match the outgoing
+      // register value of CurrMBB
+      if (SuccMBBInfo.IncomingCFARegister != CurrMBBInfo.OutgoingCFARegister) {
+        report("The incoming register of a successor is inconsistent.",
+               CurrMBB);
+        errs() << "Successor BB#" << Succ->getNumber()
+               << " has incoming register (" << SuccMBBInfo.IncomingCFARegister
+               << "), while BB#" << CurrMBB.getNumber()
+               << " has outgoing register (" << CurrMBBInfo.OutgoingCFARegister
+               << ").\n";
+        ErrorNum++;
+      }
+    }
+  }
+  return ErrorNum;
+}
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index 7ec7fda4e44..44da41ac745 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -9,6 +9,7 @@ add_llvm_library(LLVMCodeGen
   BuiltinGCs.cpp
   CalcSpillWeights.cpp
   CallingConvLower.cpp
+  CFIInstrInserter.cpp
   CodeGen.cpp
   CodeGenPrepare.cpp
   CountingFunctionInserter.cpp
diff --git a/llvm/lib/CodeGen/CodeGen.cpp b/llvm/lib/CodeGen/CodeGen.cpp
index f4ccb4889d3..c0e7511aa0c 100644
--- a/llvm/lib/CodeGen/CodeGen.cpp
+++ b/llvm/lib/CodeGen/CodeGen.cpp
@@ -23,6 +23,7 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeAtomicExpandPass(Registry);
   initializeBranchFolderPassPass(Registry);
   initializeBranchRelaxationPass(Registry);
+  initializeCFIInstrInserterPass(Registry);
   initializeCodeGenPreparePass(Registry);
   initializeCountingFunctionInserterPass(Registry);
   initializeDeadMachineInstructionElimPass(Registry);
diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index bb2dda980e4..9137c836caa 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -320,8 +320,45 @@ bool MachineOperand::isIdenticalTo(const MachineOperand &Other) const {
   }
   case MachineOperand::MO_MCSymbol:
     return getMCSymbol() == Other.getMCSymbol();
-  case MachineOperand::MO_CFIIndex:
-    return getCFIIndex() == Other.getCFIIndex();
+  case MachineOperand::MO_CFIIndex: {
+    const MachineFunction *MF = getParent()->getParent()->getParent();
+    const MachineFunction *OtherMF =
+        Other.getParent()->getParent()->getParent();
+    MCCFIInstruction Inst = MF->getFrameInstructions()[getCFIIndex()];
+    MCCFIInstruction OtherInst =
+        OtherMF->getFrameInstructions()[Other.getCFIIndex()];
+    MCCFIInstruction::OpType op = Inst.getOperation();
+    if (op != OtherInst.getOperation()) return false;
+    switch (op) {
+    case MCCFIInstruction::OpDefCfa:
+    case MCCFIInstruction::OpOffset:
+    case MCCFIInstruction::OpRelOffset:
+      if (Inst.getRegister() != OtherInst.getRegister()) return false;
+      if (Inst.getOffset() != OtherInst.getOffset()) return false;
+      break;
+    case MCCFIInstruction::OpRestore:
+    case MCCFIInstruction::OpUndefined:
+    case MCCFIInstruction::OpSameValue:
+    case MCCFIInstruction::OpDefCfaRegister:
+      if (Inst.getRegister() != OtherInst.getRegister()) return false;
+      break;
+    case MCCFIInstruction::OpRegister:
+      if (Inst.getRegister() != OtherInst.getRegister()) return false;
+      if (Inst.getRegister2() != OtherInst.getRegister2()) return false;
+      break;
+    case MCCFIInstruction::OpDefCfaOffset:
+    case MCCFIInstruction::OpAdjustCfaOffset:
+    case MCCFIInstruction::OpGnuArgsSize:
+      if (Inst.getOffset() != OtherInst.getOffset()) return false;
+      break;
+    case MCCFIInstruction::OpRememberState:
+    case MCCFIInstruction::OpRestoreState:
+    case MCCFIInstruction::OpEscape:
+    case MCCFIInstruction::OpWindowSave:
+      break;
+    }
+    return true;
+  }
   case MachineOperand::MO_Metadata:
     return getMetadata() == Other.getMetadata();
   case MachineOperand::MO_IntrinsicID:
@@ -370,8 +407,13 @@ hash_code llvm::hash_value(const MachineOperand &MO) {
     return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getMetadata());
   case MachineOperand::MO_MCSymbol:
     return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getMCSymbol());
-  case MachineOperand::MO_CFIIndex:
-    return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getCFIIndex());
+  case MachineOperand::MO_CFIIndex: {
+    const MachineFunction *MF = MO.getParent()->getParent()->getParent();
+    MCCFIInstruction Inst = MF->getFrameInstructions()[MO.getCFIIndex()];
+    return hash_combine(MO.getType(), MO.getTargetFlags(), Inst.getOperation(),
+                        Inst.getRegister(), Inst.getRegister2(),
+                        Inst.getOffset());
+  }
   case MachineOperand::MO_IntrinsicID:
     return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getIntrinsicID());
   case MachineOperand::MO_Predicate:
diff --git a/llvm/lib/CodeGen/TailDuplicator.cpp b/llvm/lib/CodeGen/TailDuplicator.cpp
index bd3a20f936d..93b53c3a1cd 100644
--- a/llvm/lib/CodeGen/TailDuplicator.cpp
+++ b/llvm/lib/CodeGen/TailDuplicator.cpp
@@ -603,8 +603,8 @@ bool TailDuplicator::shouldTailDuplicate(bool IsSimple,
     if (PreRegAlloc && MI.isCall())
       return false;
 
-    if (!MI.isPHI() && !MI.isDebugValue())
-      InstrCount += 1;
+    if (!MI.isPHI() && !MI.isMetaInstruction())
+        InstrCount += 1;
 
     if (InstrCount > MaxDuplicateCount)
       return false;
diff --git a/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp b/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
index 9dd98b4020d..22e73dc80d5 100644
--- a/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
+++ b/llvm/lib/CodeGen/TargetFrameLoweringImpl.cpp
@@ -104,3 +104,12 @@ unsigned TargetFrameLowering::getStackAlignmentSkew(
 
   return 0;
 }
+
+int TargetFrameLowering::getInitialCFAOffset(const MachineFunction &MF) const {
+  llvm_unreachable("getInitialCFAOffset() not implemented!");
+}
+
+unsigned TargetFrameLowering::getInitialCFARegister(const MachineFunction &MF)
+    const {
+  llvm_unreachable("getInitialCFARegister() not implemented!");
+}
\ No newline at end of file