Re-commit the changes from r282565 that I had to back out because of 
a linux bot test failure.  That one is fixed; hopefully there won't
be any others turned up this time.

The eh_frame augmentation code wasn't working right after the 
reorg/rewrite of the classes.  It works correctly now for the one
test that was failing - but we'll see what the test bots come up
with. 

<rdar://problem/28509178> 

llvm-svn: 282659
diff --git a/lldb/source/Plugins/UnwindAssembly/x86/CMakeLists.txt b/lldb/source/Plugins/UnwindAssembly/x86/CMakeLists.txt
index 6ae6389..024b0da 100644
--- a/lldb/source/Plugins/UnwindAssembly/x86/CMakeLists.txt
+++ b/lldb/source/Plugins/UnwindAssembly/x86/CMakeLists.txt
@@ -1,3 +1,4 @@
 add_lldb_library(lldbPluginUnwindAssemblyX86
   UnwindAssembly-x86.cpp
+  x86AssemblyInspectionEngine.cpp
   )
diff --git a/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp b/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp
index 1f01cf3..e298b85 100644
--- a/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp
+++ b/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "UnwindAssembly-x86.h"
+#include "x86AssemblyInspectionEngine.h"
 
 #include "llvm-c/Disassembler.h"
 #include "llvm/ADT/STLExtras.h"
@@ -30,1200 +31,39 @@
 using namespace lldb;
 using namespace lldb_private;
 
-enum CPU { k_i386, k_x86_64 };
-
-enum i386_register_numbers {
-  k_machine_eax = 0,
-  k_machine_ecx = 1,
-  k_machine_edx = 2,
-  k_machine_ebx = 3,
-  k_machine_esp = 4,
-  k_machine_ebp = 5,
-  k_machine_esi = 6,
-  k_machine_edi = 7,
-  k_machine_eip = 8
-};
-
-enum x86_64_register_numbers {
-  k_machine_rax = 0,
-  k_machine_rcx = 1,
-  k_machine_rdx = 2,
-  k_machine_rbx = 3,
-  k_machine_rsp = 4,
-  k_machine_rbp = 5,
-  k_machine_rsi = 6,
-  k_machine_rdi = 7,
-  k_machine_r8 = 8,
-  k_machine_r9 = 9,
-  k_machine_r10 = 10,
-  k_machine_r11 = 11,
-  k_machine_r12 = 12,
-  k_machine_r13 = 13,
-  k_machine_r14 = 14,
-  k_machine_r15 = 15,
-  k_machine_rip = 16
-};
-
-struct regmap_ent {
-  const char *name;
-  int machine_regno;
-  int lldb_regno;
-};
-
-static struct regmap_ent i386_register_map[] = {
-    {"eax", k_machine_eax, -1}, {"ecx", k_machine_ecx, -1},
-    {"edx", k_machine_edx, -1}, {"ebx", k_machine_ebx, -1},
-    {"esp", k_machine_esp, -1}, {"ebp", k_machine_ebp, -1},
-    {"esi", k_machine_esi, -1}, {"edi", k_machine_edi, -1},
-    {"eip", k_machine_eip, -1}};
-
-const int size_of_i386_register_map = llvm::array_lengthof(i386_register_map);
-
-static int i386_register_map_initialized = 0;
-
-static struct regmap_ent x86_64_register_map[] = {
-    {"rax", k_machine_rax, -1}, {"rcx", k_machine_rcx, -1},
-    {"rdx", k_machine_rdx, -1}, {"rbx", k_machine_rbx, -1},
-    {"rsp", k_machine_rsp, -1}, {"rbp", k_machine_rbp, -1},
-    {"rsi", k_machine_rsi, -1}, {"rdi", k_machine_rdi, -1},
-    {"r8", k_machine_r8, -1},   {"r9", k_machine_r9, -1},
-    {"r10", k_machine_r10, -1}, {"r11", k_machine_r11, -1},
-    {"r12", k_machine_r12, -1}, {"r13", k_machine_r13, -1},
-    {"r14", k_machine_r14, -1}, {"r15", k_machine_r15, -1},
-    {"rip", k_machine_rip, -1}};
-
-const int size_of_x86_64_register_map =
-    llvm::array_lengthof(x86_64_register_map);
-
-static int x86_64_register_map_initialized = 0;
-
-//-----------------------------------------------------------------------------------------------
-//  AssemblyParse_x86 local-file class definition & implementation functions
-//-----------------------------------------------------------------------------------------------
-
-class AssemblyParse_x86 {
-public:
-  AssemblyParse_x86(const ExecutionContext &exe_ctx, int cpu, ArchSpec &arch,
-                    AddressRange func);
-
-  ~AssemblyParse_x86();
-
-  bool get_non_call_site_unwind_plan(UnwindPlan &unwind_plan);
-
-  bool augment_unwind_plan_from_call_site(AddressRange &func,
-                                          UnwindPlan &unwind_plan);
-
-  bool get_fast_unwind_plan(AddressRange &func, UnwindPlan &unwind_plan);
-
-  bool find_first_non_prologue_insn(Address &address);
-
-private:
-  enum { kMaxInstructionByteSize = 32 };
-
-  bool nonvolatile_reg_p(int machine_regno);
-  bool push_rbp_pattern_p();
-  bool push_0_pattern_p();
-  bool mov_rsp_rbp_pattern_p();
-  bool sub_rsp_pattern_p(int &amount);
-  bool add_rsp_pattern_p(int &amount);
-  bool lea_rsp_pattern_p(int &amount);
-  bool push_reg_p(int &regno);
-  bool pop_reg_p(int &regno);
-  bool push_imm_pattern_p();
-  bool mov_reg_to_local_stack_frame_p(int &regno, int &fp_offset);
-  bool ret_pattern_p();
-  bool pop_rbp_pattern_p();
-  bool leave_pattern_p();
-  bool call_next_insn_pattern_p();
-  uint32_t extract_4(uint8_t *b);
-  bool machine_regno_to_lldb_regno(int machine_regno, uint32_t &lldb_regno);
-  bool instruction_length(Address addr, int &length);
-
-  const ExecutionContext m_exe_ctx;
-
-  AddressRange m_func_bounds;
-
-  Address m_cur_insn;
-  uint8_t m_cur_insn_bytes[kMaxInstructionByteSize];
-
-  uint32_t m_machine_ip_regnum;
-  uint32_t m_machine_sp_regnum;
-  uint32_t m_machine_fp_regnum;
-
-  uint32_t m_lldb_ip_regnum;
-  uint32_t m_lldb_sp_regnum;
-  uint32_t m_lldb_fp_regnum;
-
-  int m_wordsize;
-  int m_cpu;
-  ArchSpec m_arch;
-  ::LLVMDisasmContextRef m_disasm_context;
-
-  DISALLOW_COPY_AND_ASSIGN(AssemblyParse_x86);
-};
-
-AssemblyParse_x86::AssemblyParse_x86(const ExecutionContext &exe_ctx, int cpu,
-                                     ArchSpec &arch, AddressRange func)
-    : m_exe_ctx(exe_ctx), m_func_bounds(func), m_cur_insn(),
-      m_machine_ip_regnum(LLDB_INVALID_REGNUM),
-      m_machine_sp_regnum(LLDB_INVALID_REGNUM),
-      m_machine_fp_regnum(LLDB_INVALID_REGNUM),
-      m_lldb_ip_regnum(LLDB_INVALID_REGNUM),
-      m_lldb_sp_regnum(LLDB_INVALID_REGNUM),
-      m_lldb_fp_regnum(LLDB_INVALID_REGNUM), m_wordsize(-1), m_cpu(cpu),
-      m_arch(arch) {
-  int *initialized_flag = NULL;
-  if (cpu == k_i386) {
-    m_machine_ip_regnum = k_machine_eip;
-    m_machine_sp_regnum = k_machine_esp;
-    m_machine_fp_regnum = k_machine_ebp;
-    m_wordsize = 4;
-    initialized_flag = &i386_register_map_initialized;
-  } else {
-    m_machine_ip_regnum = k_machine_rip;
-    m_machine_sp_regnum = k_machine_rsp;
-    m_machine_fp_regnum = k_machine_rbp;
-    m_wordsize = 8;
-    initialized_flag = &x86_64_register_map_initialized;
-  }
-
-  // we only look at prologue - it will be complete earlier than 512 bytes into
-  // func
-  if (m_func_bounds.GetByteSize() == 0)
-    m_func_bounds.SetByteSize(512);
-
-  Thread *thread = m_exe_ctx.GetThreadPtr();
-  if (thread && *initialized_flag == 0) {
-    RegisterContext *reg_ctx = thread->GetRegisterContext().get();
-    if (reg_ctx) {
-      struct regmap_ent *ent;
-      int count, i;
-      if (cpu == k_i386) {
-        ent = i386_register_map;
-        count = size_of_i386_register_map;
-      } else {
-        ent = x86_64_register_map;
-        count = size_of_x86_64_register_map;
-      }
-      for (i = 0; i < count; i++, ent++) {
-        const RegisterInfo *ri = reg_ctx->GetRegisterInfoByName(ent->name);
-        if (ri)
-          ent->lldb_regno = ri->kinds[eRegisterKindLLDB];
-      }
-      *initialized_flag = 1;
-    }
-  }
-
-  // on initial construction we may not have a Thread so these have to remain
-  // uninitialized until we can get a RegisterContext to set up the register map
-  // table
-  if (*initialized_flag == 1) {
-    uint32_t lldb_regno;
-    if (machine_regno_to_lldb_regno(m_machine_sp_regnum, lldb_regno))
-      m_lldb_sp_regnum = lldb_regno;
-    if (machine_regno_to_lldb_regno(m_machine_fp_regnum, lldb_regno))
-      m_lldb_fp_regnum = lldb_regno;
-    if (machine_regno_to_lldb_regno(m_machine_ip_regnum, lldb_regno))
-      m_lldb_ip_regnum = lldb_regno;
-  }
-
-  m_disasm_context =
-      ::LLVMCreateDisasm(m_arch.GetTriple().getTriple().c_str(), (void *)this,
-                         /*TagType=*/1, NULL, NULL);
-}
-
-AssemblyParse_x86::~AssemblyParse_x86() {
-  ::LLVMDisasmDispose(m_disasm_context);
-}
-
-// This function expects an x86 native register number (i.e. the bits stripped
-// out of the
-// actual instruction), not an lldb register number.
-
-bool AssemblyParse_x86::nonvolatile_reg_p(int machine_regno) {
-  if (m_cpu == k_i386) {
-    switch (machine_regno) {
-    case k_machine_ebx:
-    case k_machine_ebp: // not actually a nonvolatile but often treated as such
-                        // by convention
-    case k_machine_esi:
-    case k_machine_edi:
-    case k_machine_esp:
-      return true;
-    default:
-      return false;
-    }
-  }
-  if (m_cpu == k_x86_64) {
-    switch (machine_regno) {
-    case k_machine_rbx:
-    case k_machine_rsp:
-    case k_machine_rbp: // not actually a nonvolatile but often treated as such
-                        // by convention
-    case k_machine_r12:
-    case k_machine_r13:
-    case k_machine_r14:
-    case k_machine_r15:
-      return true;
-    default:
-      return false;
-    }
-  }
-  return false;
-}
-
-// Macro to detect if this is a REX mode prefix byte.
-#define REX_W_PREFIX_P(opcode) (((opcode) & (~0x5)) == 0x48)
-
-// The high bit which should be added to the source register number (the "R"
-// bit)
-#define REX_W_SRCREG(opcode) (((opcode)&0x4) >> 2)
-
-// The high bit which should be added to the destination register number (the
-// "B" bit)
-#define REX_W_DSTREG(opcode) ((opcode)&0x1)
-
-// pushq %rbp [0x55]
-bool AssemblyParse_x86::push_rbp_pattern_p() {
-  uint8_t *p = m_cur_insn_bytes;
-  if (*p == 0x55)
-    return true;
-  return false;
-}
-
-// pushq $0 ; the first instruction in start() [0x6a 0x00]
-bool AssemblyParse_x86::push_0_pattern_p() {
-  uint8_t *p = m_cur_insn_bytes;
-  if (*p == 0x6a && *(p + 1) == 0x0)
-    return true;
-  return false;
-}
-
-// pushq $0
-// pushl $0
-bool AssemblyParse_x86::push_imm_pattern_p() {
-  uint8_t *p = m_cur_insn_bytes;
-  if (*p == 0x68 || *p == 0x6a)
-    return true;
-  return false;
-}
-
-// movq %rsp, %rbp [0x48 0x8b 0xec] or [0x48 0x89 0xe5]
-// movl %esp, %ebp [0x8b 0xec] or [0x89 0xe5]
-bool AssemblyParse_x86::mov_rsp_rbp_pattern_p() {
-  uint8_t *p = m_cur_insn_bytes;
-  if (m_wordsize == 8 && *p == 0x48)
-    p++;
-  if (*(p) == 0x8b && *(p + 1) == 0xec)
-    return true;
-  if (*(p) == 0x89 && *(p + 1) == 0xe5)
-    return true;
-  return false;
-}
-
-// subq $0x20, %rsp
-bool AssemblyParse_x86::sub_rsp_pattern_p(int &amount) {
-  uint8_t *p = m_cur_insn_bytes;
-  if (m_wordsize == 8 && *p == 0x48)
-    p++;
-  // 8-bit immediate operand
-  if (*p == 0x83 && *(p + 1) == 0xec) {
-    amount = (int8_t) * (p + 2);
-    return true;
-  }
-  // 32-bit immediate operand
-  if (*p == 0x81 && *(p + 1) == 0xec) {
-    amount = (int32_t)extract_4(p + 2);
-    return true;
-  }
-  return false;
-}
-
-// addq $0x20, %rsp
-bool AssemblyParse_x86::add_rsp_pattern_p(int &amount) {
-  uint8_t *p = m_cur_insn_bytes;
-  if (m_wordsize == 8 && *p == 0x48)
-    p++;
-  // 8-bit immediate operand
-  if (*p == 0x83 && *(p + 1) == 0xc4) {
-    amount = (int8_t) * (p + 2);
-    return true;
-  }
-  // 32-bit immediate operand
-  if (*p == 0x81 && *(p + 1) == 0xc4) {
-    amount = (int32_t)extract_4(p + 2);
-    return true;
-  }
-  return false;
-}
-
-// lea esp, [esp - 0x28]
-// lea esp, [esp + 0x28]
-bool AssemblyParse_x86::lea_rsp_pattern_p(int &amount) {
-  uint8_t *p = m_cur_insn_bytes;
-  if (m_wordsize == 8 && *p == 0x48)
-    p++;
-
-  // Check opcode
-  if (*p != 0x8d)
-    return false;
-
-  // 8 bit displacement
-  if (*(p + 1) == 0x64 && (*(p + 2) & 0x3f) == 0x24) {
-    amount = (int8_t) * (p + 3);
-    return true;
-  }
-
-  // 32 bit displacement
-  if (*(p + 1) == 0xa4 && (*(p + 2) & 0x3f) == 0x24) {
-    amount = (int32_t)extract_4(p + 3);
-    return true;
-  }
-
-  return false;
-}
-
-// pushq %rbx
-// pushl %ebx
-bool AssemblyParse_x86::push_reg_p(int &regno) {
-  uint8_t *p = m_cur_insn_bytes;
-  int regno_prefix_bit = 0;
-  // If we have a rex prefix byte, check to see if a B bit is set
-  if (m_wordsize == 8 && *p == 0x41) {
-    regno_prefix_bit = 1 << 3;
-    p++;
-  }
-  if (*p >= 0x50 && *p <= 0x57) {
-    regno = (*p - 0x50) | regno_prefix_bit;
-    return true;
-  }
-  return false;
-}
-
-// popq %rbx
-// popl %ebx
-bool AssemblyParse_x86::pop_reg_p(int &regno) {
-  uint8_t *p = m_cur_insn_bytes;
-  int regno_prefix_bit = 0;
-  // If we have a rex prefix byte, check to see if a B bit is set
-  if (m_wordsize == 8 && *p == 0x41) {
-    regno_prefix_bit = 1 << 3;
-    p++;
-  }
-  if (*p >= 0x58 && *p <= 0x5f) {
-    regno = (*p - 0x58) | regno_prefix_bit;
-    return true;
-  }
-  return false;
-}
-
-// popq %rbp [0x5d]
-// popl %ebp [0x5d]
-bool AssemblyParse_x86::pop_rbp_pattern_p() {
-  uint8_t *p = m_cur_insn_bytes;
-  return (*p == 0x5d);
-}
-
-// leave [0xc9]
-bool AssemblyParse_x86::leave_pattern_p() {
-  uint8_t *p = m_cur_insn_bytes;
-  return (*p == 0xc9);
-}
-
-// call $0 [0xe8 0x0 0x0 0x0 0x0]
-bool AssemblyParse_x86::call_next_insn_pattern_p() {
-  uint8_t *p = m_cur_insn_bytes;
-  return (*p == 0xe8) && (*(p + 1) == 0x0) && (*(p + 2) == 0x0) &&
-         (*(p + 3) == 0x0) && (*(p + 4) == 0x0);
-}
-
-// Look for an instruction sequence storing a nonvolatile register
-// on to the stack frame.
-
-//  movq %rax, -0x10(%rbp) [0x48 0x89 0x45 0xf0]
-//  movl %eax, -0xc(%ebp)  [0x89 0x45 0xf4]
-
-// The offset value returned in rbp_offset will be positive --
-// but it must be subtraced from the frame base register to get
-// the actual location.  The positive value returned for the offset
-// is a convention used elsewhere for CFA offsets et al.
-
-bool AssemblyParse_x86::mov_reg_to_local_stack_frame_p(int &regno,
-                                                       int &rbp_offset) {
-  uint8_t *p = m_cur_insn_bytes;
-  int src_reg_prefix_bit = 0;
-  int target_reg_prefix_bit = 0;
-
-  if (m_wordsize == 8 && REX_W_PREFIX_P(*p)) {
-    src_reg_prefix_bit = REX_W_SRCREG(*p) << 3;
-    target_reg_prefix_bit = REX_W_DSTREG(*p) << 3;
-    if (target_reg_prefix_bit == 1) {
-      // rbp/ebp don't need a prefix bit - we know this isn't the
-      // reg we care about.
-      return false;
-    }
-    p++;
-  }
-
-  if (*p == 0x89) {
-    /* Mask off the 3-5 bits which indicate the destination register
-       if this is a ModR/M byte.  */
-    int opcode_destreg_masked_out = *(p + 1) & (~0x38);
-
-    /* Is this a ModR/M byte with Mod bits 01 and R/M bits 101
-       and three bits between them, e.g. 01nnn101
-       We're looking for a destination of ebp-disp8 or ebp-disp32.   */
-    int immsize;
-    if (opcode_destreg_masked_out == 0x45)
-      immsize = 2;
-    else if (opcode_destreg_masked_out == 0x85)
-      immsize = 4;
-    else
-      return false;
-
-    int offset = 0;
-    if (immsize == 2)
-      offset = (int8_t) * (p + 2);
-    if (immsize == 4)
-      offset = (uint32_t)extract_4(p + 2);
-    if (offset > 0)
-      return false;
-
-    regno = ((*(p + 1) >> 3) & 0x7) | src_reg_prefix_bit;
-    rbp_offset = offset > 0 ? offset : -offset;
-    return true;
-  }
-  return false;
-}
-
-// ret [0xc9] or [0xc2 imm8] or [0xca imm8]
-bool AssemblyParse_x86::ret_pattern_p() {
-  uint8_t *p = m_cur_insn_bytes;
-  if (*p == 0xc9 || *p == 0xc2 || *p == 0xca || *p == 0xc3)
-    return true;
-  return false;
-}
-
-uint32_t AssemblyParse_x86::extract_4(uint8_t *b) {
-  uint32_t v = 0;
-  for (int i = 3; i >= 0; i--)
-    v = (v << 8) | b[i];
-  return v;
-}
-
-bool AssemblyParse_x86::machine_regno_to_lldb_regno(int machine_regno,
-                                                    uint32_t &lldb_regno) {
-  struct regmap_ent *ent;
-  int count, i;
-  if (m_cpu == k_i386) {
-    ent = i386_register_map;
-    count = size_of_i386_register_map;
-  } else {
-    ent = x86_64_register_map;
-    count = size_of_x86_64_register_map;
-  }
-  for (i = 0; i < count; i++, ent++) {
-    if (ent->machine_regno == machine_regno)
-      if (ent->lldb_regno != -1) {
-        lldb_regno = ent->lldb_regno;
-        return true;
-      }
-  }
-  return false;
-}
-
-bool AssemblyParse_x86::instruction_length(Address addr, int &length) {
-  const uint32_t max_op_byte_size = m_arch.GetMaximumOpcodeByteSize();
-  llvm::SmallVector<uint8_t, 32> opcode_data;
-  opcode_data.resize(max_op_byte_size);
-
-  if (!addr.IsValid())
-    return false;
-
-  const bool prefer_file_cache = true;
-  Error error;
-  Target *target = m_exe_ctx.GetTargetPtr();
-  if (target->ReadMemory(addr, prefer_file_cache, opcode_data.data(),
-                         max_op_byte_size, error) == static_cast<size_t>(-1)) {
-    return false;
-  }
-
-  char out_string[512];
-  const addr_t pc = addr.GetFileAddress();
-  const size_t inst_size = ::LLVMDisasmInstruction(
-      m_disasm_context, opcode_data.data(), max_op_byte_size,
-      pc, // PC value
-      out_string, sizeof(out_string));
-
-  length = inst_size;
-  return true;
-}
-
-bool AssemblyParse_x86::get_non_call_site_unwind_plan(UnwindPlan &unwind_plan) {
-  UnwindPlan::RowSP row(new UnwindPlan::Row);
-  m_cur_insn = m_func_bounds.GetBaseAddress();
-  addr_t current_func_text_offset = 0;
-  int current_sp_bytes_offset_from_cfa = 0;
-  UnwindPlan::Row::RegisterLocation initial_regloc;
-  Error error;
-
-  if (!m_cur_insn.IsValid()) {
-    return false;
-  }
-
-  unwind_plan.SetPlanValidAddressRange(m_func_bounds);
-  unwind_plan.SetRegisterKind(eRegisterKindLLDB);
-
-  // At the start of the function, find the CFA by adding wordsize to the SP
-  // register
-  row->SetOffset(current_func_text_offset);
-  row->GetCFAValue().SetIsRegisterPlusOffset(m_lldb_sp_regnum, m_wordsize);
-
-  // caller's stack pointer value before the call insn is the CFA address
-  initial_regloc.SetIsCFAPlusOffset(0);
-  row->SetRegisterInfo(m_lldb_sp_regnum, initial_regloc);
-
-  // saved instruction pointer can be found at CFA - wordsize.
-  current_sp_bytes_offset_from_cfa = m_wordsize;
-  initial_regloc.SetAtCFAPlusOffset(-current_sp_bytes_offset_from_cfa);
-  row->SetRegisterInfo(m_lldb_ip_regnum, initial_regloc);
-
-  unwind_plan.AppendRow(row);
-
-  // Allocate a new Row, populate it with the existing Row contents.
-  UnwindPlan::Row *newrow = new UnwindPlan::Row;
-  *newrow = *row.get();
-  row.reset(newrow);
-
-  // Track which registers have been saved so far in the prologue.
-  // If we see another push of that register, it's not part of the prologue.
-  // The register numbers used here are the machine register #'s
-  // (i386_register_numbers, x86_64_register_numbers).
-  std::vector<bool> saved_registers(32, false);
-
-  const bool prefer_file_cache = true;
-
-  // Once the prologue has completed we'll save a copy of the unwind
-  // instructions
-  // If there is an epilogue in the middle of the function, after that epilogue
-  // we'll reinstate
-  // the unwind setup -- we assume that some code path jumps over the
-  // mid-function epilogue
-
-  UnwindPlan::RowSP prologue_completed_row; // copy of prologue row of CFI
-  int prologue_completed_sp_bytes_offset_from_cfa; // The sp value before the
-                                                   // epilogue started executed
-  std::vector<bool> prologue_completed_saved_registers;
-
-  Target *target = m_exe_ctx.GetTargetPtr();
-  while (m_func_bounds.ContainsFileAddress(m_cur_insn)) {
-    int stack_offset, insn_len;
-    int machine_regno;   // register numbers masked directly out of instructions
-    uint32_t lldb_regno; // register numbers in lldb's eRegisterKindLLDB
-                         // numbering scheme
-
-    bool in_epilogue = false; // we're in the middle of an epilogue sequence
-    bool row_updated = false; // The UnwindPlan::Row 'row' has been updated
-
-    if (!instruction_length(m_cur_insn, insn_len) || insn_len == 0 ||
-        insn_len > kMaxInstructionByteSize) {
-      // An unrecognized/junk instruction
-      break;
-    }
-
-    if (target->ReadMemory(m_cur_insn, prefer_file_cache, m_cur_insn_bytes,
-                           insn_len, error) == static_cast<size_t>(-1)) {
-      // Error reading the instruction out of the file, stop scanning
-      break;
-    }
-
-    if (push_rbp_pattern_p()) {
-      current_sp_bytes_offset_from_cfa += m_wordsize;
-      row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
-      UnwindPlan::Row::RegisterLocation regloc;
-      regloc.SetAtCFAPlusOffset(-row->GetCFAValue().GetOffset());
-      row->SetRegisterInfo(m_lldb_fp_regnum, regloc);
-      saved_registers[m_machine_fp_regnum] = true;
-      row_updated = true;
-    }
-
-    else if (mov_rsp_rbp_pattern_p()) {
-      row->GetCFAValue().SetIsRegisterPlusOffset(
-          m_lldb_fp_regnum, row->GetCFAValue().GetOffset());
-      row_updated = true;
-    }
-
-    // This is the start() function (or a pthread equivalent), it starts with a
-    // pushl $0x0 which puts the
-    // saved pc value of 0 on the stack.  In this case we want to pretend we
-    // didn't see a stack movement at all --
-    // normally the saved pc value is already on the stack by the time the
-    // function starts executing.
-    else if (push_0_pattern_p()) {
-    }
-
-    else if (push_reg_p(machine_regno)) {
-      current_sp_bytes_offset_from_cfa += m_wordsize;
-      // the PUSH instruction has moved the stack pointer - if the CFA is set in
-      // terms of the stack pointer,
-      // we need to add a new row of instructions.
-      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
-        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
-        row_updated = true;
-      }
-      // record where non-volatile (callee-saved, spilled) registers are saved
-      // on the stack
-      if (nonvolatile_reg_p(machine_regno) &&
-          machine_regno_to_lldb_regno(machine_regno, lldb_regno) &&
-          saved_registers[machine_regno] == false) {
-        UnwindPlan::Row::RegisterLocation regloc;
-        regloc.SetAtCFAPlusOffset(-current_sp_bytes_offset_from_cfa);
-        row->SetRegisterInfo(lldb_regno, regloc);
-        saved_registers[machine_regno] = true;
-        row_updated = true;
-      }
-    }
-
-    else if (pop_reg_p(machine_regno)) {
-      current_sp_bytes_offset_from_cfa -= m_wordsize;
-
-      if (nonvolatile_reg_p(machine_regno) &&
-          machine_regno_to_lldb_regno(machine_regno, lldb_regno) &&
-          saved_registers[machine_regno] == true) {
-        saved_registers[machine_regno] = false;
-        row->RemoveRegisterInfo(lldb_regno);
-
-        if (machine_regno == (int)m_machine_fp_regnum) {
-          row->GetCFAValue().SetIsRegisterPlusOffset(
-              m_lldb_sp_regnum, row->GetCFAValue().GetOffset());
-        }
-
-        in_epilogue = true;
-        row_updated = true;
-      }
-
-      // the POP instruction has moved the stack pointer - if the CFA is set in
-      // terms of the stack pointer,
-      // we need to add a new row of instructions.
-      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
-        row->GetCFAValue().SetIsRegisterPlusOffset(
-            m_lldb_sp_regnum, current_sp_bytes_offset_from_cfa);
-        row_updated = true;
-      }
-    }
-
-    // The LEAVE instruction moves the value from rbp into rsp and pops
-    // a value off the stack into rbp (restoring the caller's rbp value).
-    // It is the opposite of ENTER, or 'push rbp, mov rsp rbp'.
-    else if (leave_pattern_p()) {
-      // We're going to copy the value in rbp into rsp, so re-set the sp offset
-      // based on the CFAValue.  Also, adjust it to recognize that we're popping
-      // the saved rbp value off the stack.
-      current_sp_bytes_offset_from_cfa = row->GetCFAValue().GetOffset();
-      current_sp_bytes_offset_from_cfa -= m_wordsize;
-      row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
-
-      // rbp is restored to the caller's value
-      saved_registers[m_machine_fp_regnum] = false;
-      row->RemoveRegisterInfo(m_lldb_fp_regnum);
-
-      // cfa is now in terms of rsp again.
-      row->GetCFAValue().SetIsRegisterPlusOffset(
-          m_lldb_sp_regnum, row->GetCFAValue().GetOffset());
-      row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
-
-      in_epilogue = true;
-      row_updated = true;
-    }
-
-    else if (mov_reg_to_local_stack_frame_p(machine_regno, stack_offset) &&
-             nonvolatile_reg_p(machine_regno) &&
-             machine_regno_to_lldb_regno(machine_regno, lldb_regno) &&
-             saved_registers[machine_regno] == false) {
-      saved_registers[machine_regno] = true;
-
-      UnwindPlan::Row::RegisterLocation regloc;
-
-      // stack_offset for 'movq %r15, -80(%rbp)' will be 80.
-      // In the Row, we want to express this as the offset from the CFA.  If the
-      // frame base
-      // is rbp (like the above instruction), the CFA offset for rbp is probably
-      // 16.  So we
-      // want to say that the value is stored at the CFA address - 96.
-      regloc.SetAtCFAPlusOffset(
-          -(stack_offset + row->GetCFAValue().GetOffset()));
-
-      row->SetRegisterInfo(lldb_regno, regloc);
-
-      row_updated = true;
-    }
-
-    else if (sub_rsp_pattern_p(stack_offset)) {
-      current_sp_bytes_offset_from_cfa += stack_offset;
-      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
-        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
-        row_updated = true;
-      }
-    }
-
-    else if (add_rsp_pattern_p(stack_offset)) {
-      current_sp_bytes_offset_from_cfa -= stack_offset;
-      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
-        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
-        row_updated = true;
-      }
-      in_epilogue = true;
-    }
-
-    else if (lea_rsp_pattern_p(stack_offset)) {
-      current_sp_bytes_offset_from_cfa -= stack_offset;
-      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
-        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
-        row_updated = true;
-      }
-      if (stack_offset > 0)
-        in_epilogue = true;
-    }
-
-    else if (ret_pattern_p() && prologue_completed_row.get()) {
-      // Reinstate the saved prologue setup for any instructions
-      // that come after the ret instruction
-
-      UnwindPlan::Row *newrow = new UnwindPlan::Row;
-      *newrow = *prologue_completed_row.get();
-      row.reset(newrow);
-      current_sp_bytes_offset_from_cfa =
-          prologue_completed_sp_bytes_offset_from_cfa;
-
-      saved_registers.clear();
-      saved_registers.resize(prologue_completed_saved_registers.size(), false);
-      for (size_t i = 0; i < prologue_completed_saved_registers.size(); ++i) {
-        saved_registers[i] = prologue_completed_saved_registers[i];
-      }
-
-      in_epilogue = true;
-      row_updated = true;
-    }
-
-    // call next instruction
-    //     call 0
-    //  => pop  %ebx
-    // This is used in i386 programs to get the PIC base address for finding
-    // global data
-    else if (call_next_insn_pattern_p()) {
-      current_sp_bytes_offset_from_cfa += m_wordsize;
-      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
-        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
-        row_updated = true;
-      }
-    }
-
-    if (row_updated) {
-      if (current_func_text_offset + insn_len < m_func_bounds.GetByteSize()) {
-        row->SetOffset(current_func_text_offset + insn_len);
-        unwind_plan.AppendRow(row);
-        // Allocate a new Row, populate it with the existing Row contents.
-        newrow = new UnwindPlan::Row;
-        *newrow = *row.get();
-        row.reset(newrow);
-      }
-    }
-
-    if (in_epilogue == false && row_updated) {
-      // If we're not in an epilogue sequence, save the updated Row
-      UnwindPlan::Row *newrow = new UnwindPlan::Row;
-      *newrow = *row.get();
-      prologue_completed_row.reset(newrow);
-
-      prologue_completed_saved_registers.clear();
-      prologue_completed_saved_registers.resize(saved_registers.size(), false);
-      for (size_t i = 0; i < saved_registers.size(); ++i) {
-        prologue_completed_saved_registers[i] = saved_registers[i];
-      }
-    }
-
-    // We may change the sp value without adding a new Row necessarily -- keep
-    // track of it either way.
-    if (in_epilogue == false) {
-      prologue_completed_sp_bytes_offset_from_cfa =
-          current_sp_bytes_offset_from_cfa;
-    }
-
-    m_cur_insn.SetOffset(m_cur_insn.GetOffset() + insn_len);
-    current_func_text_offset += insn_len;
-  }
-
-  unwind_plan.SetSourceName("assembly insn profiling");
-  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
-  unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
-
-  return true;
-}
-
-bool AssemblyParse_x86::augment_unwind_plan_from_call_site(
-    AddressRange &func, UnwindPlan &unwind_plan) {
-  // Is func address valid?
-  Address addr_start = func.GetBaseAddress();
-  if (!addr_start.IsValid())
-    return false;
-
-  // Is original unwind_plan valid?
-  // unwind_plan should have at least one row which is ABI-default (CFA register
-  // is sp),
-  // and another row in mid-function.
-  if (unwind_plan.GetRowCount() < 2)
-    return false;
-  UnwindPlan::RowSP first_row = unwind_plan.GetRowAtIndex(0);
-  if (first_row->GetOffset() != 0)
-    return false;
-  uint32_t cfa_reg = m_exe_ctx.GetThreadPtr()
-                         ->GetRegisterContext()
-                         ->ConvertRegisterKindToRegisterNumber(
-                             unwind_plan.GetRegisterKind(),
-                             first_row->GetCFAValue().GetRegisterNumber());
-  if (cfa_reg != m_lldb_sp_regnum ||
-      first_row->GetCFAValue().GetOffset() != m_wordsize)
-    return false;
-
-  UnwindPlan::RowSP original_last_row = unwind_plan.GetRowForFunctionOffset(-1);
-
-  Target *target = m_exe_ctx.GetTargetPtr();
-  m_cur_insn = func.GetBaseAddress();
-  uint64_t offset = 0;
-  int row_id = 1;
-  bool unwind_plan_updated = false;
-  UnwindPlan::RowSP row(new UnwindPlan::Row(*first_row));
-
-  // After a mid-function epilogue we will need to re-insert the original unwind
-  // rules
-  // so unwinds work for the remainder of the function.  These aren't common
-  // with clang/gcc
-  // on x86 but it is possible.
-  bool reinstate_unwind_state = false;
-
-  while (func.ContainsFileAddress(m_cur_insn)) {
-    int insn_len;
-    if (!instruction_length(m_cur_insn, insn_len) || insn_len == 0 ||
-        insn_len > kMaxInstructionByteSize) {
-      // An unrecognized/junk instruction.
-      break;
-    }
-    const bool prefer_file_cache = true;
-    Error error;
-    if (target->ReadMemory(m_cur_insn, prefer_file_cache, m_cur_insn_bytes,
-                           insn_len, error) == static_cast<size_t>(-1)) {
-      // Error reading the instruction out of the file, stop scanning.
-      break;
-    }
-
-    // Advance offsets.
-    offset += insn_len;
-    m_cur_insn.SetOffset(m_cur_insn.GetOffset() + insn_len);
-
-    if (reinstate_unwind_state) {
-      // that was the last instruction of this function
-      if (func.ContainsFileAddress(m_cur_insn) == false)
-        continue;
-
-      UnwindPlan::RowSP new_row(new UnwindPlan::Row());
-      *new_row = *original_last_row;
-      new_row->SetOffset(offset);
-      unwind_plan.AppendRow(new_row);
-      row.reset(new UnwindPlan::Row());
-      *row = *new_row;
-      reinstate_unwind_state = false;
-      unwind_plan_updated = true;
-      continue;
-    }
-
-    // If we already have one row for this instruction, we can continue.
-    while (row_id < unwind_plan.GetRowCount() &&
-           unwind_plan.GetRowAtIndex(row_id)->GetOffset() <= offset) {
-      row_id++;
-    }
-    UnwindPlan::RowSP original_row = unwind_plan.GetRowAtIndex(row_id - 1);
-    if (original_row->GetOffset() == offset) {
-      *row = *original_row;
-      continue;
-    }
-
-    if (row_id == 0) {
-      // If we are here, compiler didn't generate CFI for prologue.
-      // This won't happen to GCC or clang.
-      // In this case, bail out directly.
-      return false;
-    }
-
-    // Inspect the instruction to check if we need a new row for it.
-    cfa_reg = m_exe_ctx.GetThreadPtr()
-                  ->GetRegisterContext()
-                  ->ConvertRegisterKindToRegisterNumber(
-                      unwind_plan.GetRegisterKind(),
-                      row->GetCFAValue().GetRegisterNumber());
-    if (cfa_reg == m_lldb_sp_regnum) {
-      // CFA register is sp.
-
-      // call next instruction
-      //     call 0
-      //  => pop  %ebx
-      if (call_next_insn_pattern_p()) {
-        row->SetOffset(offset);
-        row->GetCFAValue().IncOffset(m_wordsize);
-
-        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
-        unwind_plan.InsertRow(new_row);
-        unwind_plan_updated = true;
-        continue;
-      }
-
-      // push/pop register
-      int regno;
-      if (push_reg_p(regno)) {
-        row->SetOffset(offset);
-        row->GetCFAValue().IncOffset(m_wordsize);
-
-        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
-        unwind_plan.InsertRow(new_row);
-        unwind_plan_updated = true;
-        continue;
-      }
-      if (pop_reg_p(regno)) {
-        // Technically, this might be a nonvolatile register recover in
-        // epilogue.
-        // We should reset RegisterInfo for the register.
-        // But in practice, previous rule for the register is still valid...
-        // So we ignore this case.
-
-        row->SetOffset(offset);
-        row->GetCFAValue().IncOffset(-m_wordsize);
-
-        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
-        unwind_plan.InsertRow(new_row);
-        unwind_plan_updated = true;
-        continue;
-      }
-
-      // push imm
-      if (push_imm_pattern_p()) {
-        row->SetOffset(offset);
-        row->GetCFAValue().IncOffset(m_wordsize);
-        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
-        unwind_plan.InsertRow(new_row);
-        unwind_plan_updated = true;
-        continue;
-      }
-
-      // add/sub %rsp/%esp
-      int amount;
-      if (add_rsp_pattern_p(amount)) {
-        row->SetOffset(offset);
-        row->GetCFAValue().IncOffset(-amount);
-
-        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
-        unwind_plan.InsertRow(new_row);
-        unwind_plan_updated = true;
-        continue;
-      }
-      if (sub_rsp_pattern_p(amount)) {
-        row->SetOffset(offset);
-        row->GetCFAValue().IncOffset(amount);
-
-        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
-        unwind_plan.InsertRow(new_row);
-        unwind_plan_updated = true;
-        continue;
-      }
-
-      // lea %rsp, [%rsp + $offset]
-      if (lea_rsp_pattern_p(amount)) {
-        row->SetOffset(offset);
-        row->GetCFAValue().IncOffset(-amount);
-
-        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
-        unwind_plan.InsertRow(new_row);
-        unwind_plan_updated = true;
-        continue;
-      }
-
-      if (ret_pattern_p()) {
-        reinstate_unwind_state = true;
-        continue;
-      }
-    } else if (cfa_reg == m_lldb_fp_regnum) {
-      // CFA register is fp.
-
-      // The only case we care about is epilogue:
-      //     [0x5d] pop %rbp/%ebp
-      //  => [0xc3] ret
-      if (pop_rbp_pattern_p() || leave_pattern_p()) {
-        if (target->ReadMemory(m_cur_insn, prefer_file_cache, m_cur_insn_bytes,
-                               1, error) != static_cast<size_t>(-1) &&
-            ret_pattern_p()) {
-          row->SetOffset(offset);
-          row->GetCFAValue().SetIsRegisterPlusOffset(
-              first_row->GetCFAValue().GetRegisterNumber(), m_wordsize);
-
-          UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
-          unwind_plan.InsertRow(new_row);
-          unwind_plan_updated = true;
-          reinstate_unwind_state = true;
-          continue;
-        }
-      }
-    } else {
-      // CFA register is not sp or fp.
-
-      // This must be hand-written assembly.
-      // Just trust eh_frame and assume we have finished.
-      break;
-    }
-  }
-
-  unwind_plan.SetPlanValidAddressRange(func);
-  if (unwind_plan_updated) {
-    std::string unwind_plan_source(unwind_plan.GetSourceName().AsCString());
-    unwind_plan_source += " plus augmentation from assembly parsing";
-    unwind_plan.SetSourceName(unwind_plan_source.c_str());
-    unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
-    unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
-  }
-  return true;
-}
-
-/* The "fast unwind plan" is valid for functions that follow the usual
-   convention of
-   using the frame pointer register (ebp, rbp), i.e. the function prologue looks
-   like
-     push   %rbp      [0x55]
-     mov    %rsp,%rbp [0x48 0x89 0xe5]   (this is a 2-byte insn seq on i386)
-*/
-
-bool AssemblyParse_x86::get_fast_unwind_plan(AddressRange &func,
-                                             UnwindPlan &unwind_plan) {
-  UnwindPlan::RowSP row(new UnwindPlan::Row);
-  UnwindPlan::Row::RegisterLocation pc_reginfo;
-  UnwindPlan::Row::RegisterLocation sp_reginfo;
-  UnwindPlan::Row::RegisterLocation fp_reginfo;
-  unwind_plan.SetRegisterKind(eRegisterKindLLDB);
-
-  if (!func.GetBaseAddress().IsValid())
-    return false;
-
-  Target *target = m_exe_ctx.GetTargetPtr();
-
-  uint8_t bytebuf[4];
-  Error error;
-  const bool prefer_file_cache = true;
-  if (target->ReadMemory(func.GetBaseAddress(), prefer_file_cache, bytebuf,
-                         sizeof(bytebuf), error) == static_cast<size_t>(-1))
-    return false;
-
-  uint8_t i386_prologue[] = {0x55, 0x89, 0xe5};
-  uint8_t x86_64_prologue[] = {0x55, 0x48, 0x89, 0xe5};
-  int prologue_size;
-
-  if (memcmp(bytebuf, i386_prologue, sizeof(i386_prologue)) == 0) {
-    prologue_size = sizeof(i386_prologue);
-  } else if (memcmp(bytebuf, x86_64_prologue, sizeof(x86_64_prologue)) == 0) {
-    prologue_size = sizeof(x86_64_prologue);
-  } else {
-    return false;
-  }
-
-  pc_reginfo.SetAtCFAPlusOffset(-m_wordsize);
-  row->SetRegisterInfo(m_lldb_ip_regnum, pc_reginfo);
-
-  sp_reginfo.SetIsCFAPlusOffset(0);
-  row->SetRegisterInfo(m_lldb_sp_regnum, sp_reginfo);
-
-  // Zero instructions into the function
-  row->GetCFAValue().SetIsRegisterPlusOffset(m_lldb_sp_regnum, m_wordsize);
-  row->SetOffset(0);
-  unwind_plan.AppendRow(row);
-  UnwindPlan::Row *newrow = new UnwindPlan::Row;
-  *newrow = *row.get();
-  row.reset(newrow);
-
-  // push %rbp has executed - stack moved, rbp now saved
-  row->GetCFAValue().IncOffset(m_wordsize);
-  fp_reginfo.SetAtCFAPlusOffset(2 * -m_wordsize);
-  row->SetRegisterInfo(m_lldb_fp_regnum, fp_reginfo);
-  row->SetOffset(1);
-  unwind_plan.AppendRow(row);
-
-  newrow = new UnwindPlan::Row;
-  *newrow = *row.get();
-  row.reset(newrow);
-
-  // mov %rsp, %rbp has executed
-  row->GetCFAValue().SetIsRegisterPlusOffset(m_lldb_fp_regnum, 2 * m_wordsize);
-  row->SetOffset(prologue_size); /// 3 or 4 bytes depending on arch
-  unwind_plan.AppendRow(row);
-
-  newrow = new UnwindPlan::Row;
-  *newrow = *row.get();
-  row.reset(newrow);
-
-  unwind_plan.SetPlanValidAddressRange(func);
-  unwind_plan.SetSourceName("fast unwind assembly profiling");
-  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
-  unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
-  return true;
-}
-
-bool AssemblyParse_x86::find_first_non_prologue_insn(Address &address) {
-  m_cur_insn = m_func_bounds.GetBaseAddress();
-  if (!m_cur_insn.IsValid()) {
-    return false;
-  }
-
-  const bool prefer_file_cache = true;
-  Target *target = m_exe_ctx.GetTargetPtr();
-  while (m_func_bounds.ContainsFileAddress(m_cur_insn)) {
-    Error error;
-    int insn_len, offset, regno;
-    if (!instruction_length(m_cur_insn, insn_len) ||
-        insn_len > kMaxInstructionByteSize || insn_len == 0) {
-      // An error parsing the instruction, i.e. probably data/garbage - stop
-      // scanning
-      break;
-    }
-    if (target->ReadMemory(m_cur_insn, prefer_file_cache, m_cur_insn_bytes,
-                           insn_len, error) == static_cast<size_t>(-1)) {
-      // Error reading the instruction out of the file, stop scanning
-      break;
-    }
-
-    if (push_rbp_pattern_p() || mov_rsp_rbp_pattern_p() ||
-        sub_rsp_pattern_p(offset) || push_reg_p(regno) ||
-        mov_reg_to_local_stack_frame_p(regno, offset) ||
-        (lea_rsp_pattern_p(offset) && offset < 0)) {
-      m_cur_insn.SetOffset(m_cur_insn.GetOffset() + insn_len);
-      continue;
-    }
-
-    // Unknown non-prologue instruction - stop scanning
-    break;
-  }
-
-  address = m_cur_insn;
-  return true;
-}
-
 //-----------------------------------------------------------------------------------------------
 //  UnwindAssemblyParser_x86 method definitions
 //-----------------------------------------------------------------------------------------------
 
-UnwindAssembly_x86::UnwindAssembly_x86(const ArchSpec &arch, int cpu)
-    : lldb_private::UnwindAssembly(arch), m_cpu(cpu), m_arch(arch) {}
+UnwindAssembly_x86::UnwindAssembly_x86(const ArchSpec &arch)
+    : lldb_private::UnwindAssembly(arch),
+      m_assembly_inspection_engine(new x86AssemblyInspectionEngine(arch)) {}
 
-UnwindAssembly_x86::~UnwindAssembly_x86() {}
+UnwindAssembly_x86::~UnwindAssembly_x86() {
+  delete m_assembly_inspection_engine;
+}
 
 bool UnwindAssembly_x86::GetNonCallSiteUnwindPlanFromAssembly(
     AddressRange &func, Thread &thread, UnwindPlan &unwind_plan) {
-  ExecutionContext exe_ctx(thread.shared_from_this());
-  AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
-  return asm_parse.get_non_call_site_unwind_plan(unwind_plan);
+  if (!func.GetBaseAddress().IsValid() || func.GetByteSize() == 0)
+    return false;
+  if (m_assembly_inspection_engine == nullptr)
+    return false;
+  ProcessSP process_sp(thread.GetProcess());
+  if (process_sp.get() == nullptr)
+    return false;
+  const bool prefer_file_cache = true;
+  std::vector<uint8_t> function_text(func.GetByteSize());
+  Error error;
+  if (process_sp->GetTarget().ReadMemory(
+          func.GetBaseAddress(), prefer_file_cache, function_text.data(),
+          func.GetByteSize(), error) == func.GetByteSize()) {
+    RegisterContextSP reg_ctx(thread.GetRegisterContext());
+    m_assembly_inspection_engine->Initialize(reg_ctx);
+    return m_assembly_inspection_engine->GetNonCallSiteUnwindPlanFromAssembly(
+        function_text.data(), func.GetByteSize(), func, unwind_plan);
+  }
+  return false;
 }
 
 bool UnwindAssembly_x86::AugmentUnwindPlanFromCallSite(
@@ -1235,9 +75,10 @@
 
   int wordsize = 8;
   ProcessSP process_sp(thread.GetProcess());
-  if (process_sp) {
-    wordsize = process_sp->GetTarget().GetArchitecture().GetAddressByteSize();
-  }
+  if (process_sp.get() == nullptr)
+    return false;
+
+  wordsize = process_sp->GetTarget().GetArchitecture().GetAddressByteSize();
 
   RegisterNumber sp_regnum(thread, eRegisterKindGeneric,
                            LLDB_REGNUM_GENERIC_SP);
@@ -1314,9 +155,21 @@
   }
 
   if (do_augment_unwindplan) {
-    ExecutionContext exe_ctx(thread.shared_from_this());
-    AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
-    return asm_parse.augment_unwind_plan_from_call_site(func, unwind_plan);
+    if (!func.GetBaseAddress().IsValid() || func.GetByteSize() == 0)
+      return false;
+    if (m_assembly_inspection_engine == nullptr)
+      return false;
+    const bool prefer_file_cache = true;
+    std::vector<uint8_t> function_text(func.GetByteSize());
+    Error error;
+    if (process_sp->GetTarget().ReadMemory(
+            func.GetBaseAddress(), prefer_file_cache, function_text.data(),
+            func.GetByteSize(), error) == func.GetByteSize()) {
+      RegisterContextSP reg_ctx(thread.GetRegisterContext());
+      m_assembly_inspection_engine->Initialize(reg_ctx);
+      return m_assembly_inspection_engine->AugmentUnwindPlanFromCallSite(
+          function_text.data(), func.GetByteSize(), func, unwind_plan, reg_ctx);
+    }
   }
 
   return false;
@@ -1362,16 +215,38 @@
 bool UnwindAssembly_x86::FirstNonPrologueInsn(
     AddressRange &func, const ExecutionContext &exe_ctx,
     Address &first_non_prologue_insn) {
-  AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
-  return asm_parse.find_first_non_prologue_insn(first_non_prologue_insn);
+
+  if (!func.GetBaseAddress().IsValid())
+    return false;
+
+  Target *target = exe_ctx.GetTargetPtr();
+  if (target == nullptr)
+    return false;
+
+  if (m_assembly_inspection_engine == nullptr)
+    return false;
+
+  const bool prefer_file_cache = true;
+  std::vector<uint8_t> function_text(func.GetByteSize());
+  Error error;
+  if (target->ReadMemory(func.GetBaseAddress(), prefer_file_cache,
+                         function_text.data(), func.GetByteSize(),
+                         error) == func.GetByteSize()) {
+    size_t offset;
+    if (m_assembly_inspection_engine->FindFirstNonPrologueInstruction(
+            function_text.data(), func.GetByteSize(), offset)) {
+      first_non_prologue_insn = func.GetBaseAddress();
+      first_non_prologue_insn.Slide(offset);
+    }
+    return true;
+  }
+  return false;
 }
 
 UnwindAssembly *UnwindAssembly_x86::CreateInstance(const ArchSpec &arch) {
   const llvm::Triple::ArchType cpu = arch.GetMachine();
-  if (cpu == llvm::Triple::x86)
-    return new UnwindAssembly_x86(arch, k_i386);
-  else if (cpu == llvm::Triple::x86_64)
-    return new UnwindAssembly_x86(arch, k_x86_64);
+  if (cpu == llvm::Triple::x86 || cpu == llvm::Triple::x86_64)
+    return new UnwindAssembly_x86(arch);
   return NULL;
 }
 
diff --git a/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.h b/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.h
index 3993178..2beaa4a 100644
--- a/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.h
+++ b/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.h
@@ -13,7 +13,7 @@
 // C Includes
 // C++ Includes
 // Other libraries and framework includes
-#include "llvm-c/Disassembler.h"
+#include "x86AssemblyInspectionEngine.h"
 
 // Project includes
 #include "lldb/Target/UnwindAssembly.h"
@@ -62,10 +62,11 @@
   uint32_t GetPluginVersion() override;
 
 private:
-  UnwindAssembly_x86(const lldb_private::ArchSpec &arch, int cpu);
+  UnwindAssembly_x86(const lldb_private::ArchSpec &arch);
 
-  int m_cpu;
   lldb_private::ArchSpec m_arch;
+
+  lldb_private::x86AssemblyInspectionEngine *m_assembly_inspection_engine;
 };
 
 #endif // liblldb_UnwindAssembly_x86_h_
diff --git a/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp
new file mode 100644
index 0000000..1384cf1
--- /dev/null
+++ b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp
@@ -0,0 +1,1112 @@
+//===-- x86AssemblyInspectionEngine.cpp -------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "x86AssemblyInspectionEngine.h"
+
+#include "llvm-c/Disassembler.h"
+
+#include "lldb/Core/Address.h"
+#include "lldb/Symbol/UnwindPlan.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/UnwindAssembly.h"
+
+using namespace lldb_private;
+using namespace lldb;
+
+x86AssemblyInspectionEngine::x86AssemblyInspectionEngine(const ArchSpec &arch)
+    : m_cur_insn(nullptr), m_machine_ip_regnum(LLDB_INVALID_REGNUM),
+      m_machine_sp_regnum(LLDB_INVALID_REGNUM),
+      m_machine_fp_regnum(LLDB_INVALID_REGNUM),
+      m_lldb_ip_regnum(LLDB_INVALID_REGNUM),
+      m_lldb_sp_regnum(LLDB_INVALID_REGNUM),
+      m_lldb_fp_regnum(LLDB_INVALID_REGNUM),
+
+      m_reg_map(), m_arch(arch), m_cpu(k_cpu_unspecified), m_wordsize(-1),
+      m_register_map_initialized(false), m_disasm_context() {
+  m_disasm_context = ::LLVMCreateDisasm("x86_64-apple-macosx", nullptr,
+                                        /*TagType=*/1, nullptr, nullptr);
+  //      ::LLVMCreateDisasm(arch.GetTriple().getTriple().c_str(), nullptr,
+  //                         /*TagType=*/1, nullptr, nullptr);
+}
+
+x86AssemblyInspectionEngine::~x86AssemblyInspectionEngine() {
+  ::LLVMDisasmDispose(m_disasm_context);
+}
+
+void x86AssemblyInspectionEngine::Initialize(RegisterContextSP &reg_ctx) {
+  m_cpu = k_cpu_unspecified;
+  m_wordsize = -1;
+  m_register_map_initialized = false;
+
+  const llvm::Triple::ArchType cpu = m_arch.GetMachine();
+  if (cpu == llvm::Triple::x86)
+    m_cpu = k_i386;
+  else if (cpu == llvm::Triple::x86_64)
+    m_cpu = k_x86_64;
+
+  if (m_cpu == k_cpu_unspecified)
+    return;
+
+  if (reg_ctx.get() == nullptr)
+    return;
+
+  if (m_cpu == k_i386) {
+    m_machine_ip_regnum = k_machine_eip;
+    m_machine_sp_regnum = k_machine_esp;
+    m_machine_fp_regnum = k_machine_ebp;
+    m_wordsize = 4;
+
+    struct lldb_reg_info reginfo;
+    reginfo.name = "eax";
+    m_reg_map[k_machine_eax] = reginfo;
+    reginfo.name = "edx";
+    m_reg_map[k_machine_edx] = reginfo;
+    reginfo.name = "esp";
+    m_reg_map[k_machine_esp] = reginfo;
+    reginfo.name = "esi";
+    m_reg_map[k_machine_esi] = reginfo;
+    reginfo.name = "eip";
+    m_reg_map[k_machine_eip] = reginfo;
+    reginfo.name = "ecx";
+    m_reg_map[k_machine_ecx] = reginfo;
+    reginfo.name = "ebx";
+    m_reg_map[k_machine_ebx] = reginfo;
+    reginfo.name = "ebp";
+    m_reg_map[k_machine_ebp] = reginfo;
+    reginfo.name = "edi";
+    m_reg_map[k_machine_edi] = reginfo;
+  } else {
+    m_machine_ip_regnum = k_machine_rip;
+    m_machine_sp_regnum = k_machine_rsp;
+    m_machine_fp_regnum = k_machine_rbp;
+    m_wordsize = 8;
+
+    struct lldb_reg_info reginfo;
+    reginfo.name = "rax";
+    m_reg_map[k_machine_rax] = reginfo;
+    reginfo.name = "rdx";
+    m_reg_map[k_machine_rdx] = reginfo;
+    reginfo.name = "rsp";
+    m_reg_map[k_machine_rsp] = reginfo;
+    reginfo.name = "rsi";
+    m_reg_map[k_machine_rsi] = reginfo;
+    reginfo.name = "r8";
+    m_reg_map[k_machine_r8] = reginfo;
+    reginfo.name = "r10";
+    m_reg_map[k_machine_r10] = reginfo;
+    reginfo.name = "r12";
+    m_reg_map[k_machine_r12] = reginfo;
+    reginfo.name = "r14";
+    m_reg_map[k_machine_r14] = reginfo;
+    reginfo.name = "rip";
+    m_reg_map[k_machine_rip] = reginfo;
+    reginfo.name = "rcx";
+    m_reg_map[k_machine_rcx] = reginfo;
+    reginfo.name = "rbx";
+    m_reg_map[k_machine_rbx] = reginfo;
+    reginfo.name = "rbp";
+    m_reg_map[k_machine_rbp] = reginfo;
+    reginfo.name = "rdi";
+    m_reg_map[k_machine_rdi] = reginfo;
+    reginfo.name = "r9";
+    m_reg_map[k_machine_r9] = reginfo;
+    reginfo.name = "r11";
+    m_reg_map[k_machine_r11] = reginfo;
+    reginfo.name = "r13";
+    m_reg_map[k_machine_r13] = reginfo;
+    reginfo.name = "r15";
+    m_reg_map[k_machine_r15] = reginfo;
+  }
+
+  for (MachineRegnumToNameAndLLDBRegnum::iterator it = m_reg_map.begin();
+       it != m_reg_map.end(); ++it) {
+    const RegisterInfo *ri = reg_ctx->GetRegisterInfoByName(it->second.name);
+    if (ri)
+      it->second.lldb_regnum = ri->kinds[eRegisterKindLLDB];
+  }
+
+  uint32_t lldb_regno;
+  if (machine_regno_to_lldb_regno(m_machine_sp_regnum, lldb_regno))
+    m_lldb_sp_regnum = lldb_regno;
+  if (machine_regno_to_lldb_regno(m_machine_fp_regnum, lldb_regno))
+    m_lldb_fp_regnum = lldb_regno;
+  if (machine_regno_to_lldb_regno(m_machine_ip_regnum, lldb_regno))
+    m_lldb_ip_regnum = lldb_regno;
+
+  m_register_map_initialized = true;
+}
+
+void x86AssemblyInspectionEngine::Initialize(
+    std::vector<lldb_reg_info> &reg_info) {
+  m_cpu = k_cpu_unspecified;
+  m_wordsize = -1;
+  m_register_map_initialized = false;
+
+  const llvm::Triple::ArchType cpu = m_arch.GetMachine();
+  if (cpu == llvm::Triple::x86)
+    m_cpu = k_i386;
+  else if (cpu == llvm::Triple::x86_64)
+    m_cpu = k_x86_64;
+
+  if (m_cpu == k_cpu_unspecified)
+    return;
+
+  if (m_cpu == k_i386) {
+    m_machine_ip_regnum = k_machine_eip;
+    m_machine_sp_regnum = k_machine_esp;
+    m_machine_fp_regnum = k_machine_ebp;
+    m_wordsize = 4;
+
+    struct lldb_reg_info reginfo;
+    reginfo.name = "eax";
+    m_reg_map[k_machine_eax] = reginfo;
+    reginfo.name = "edx";
+    m_reg_map[k_machine_edx] = reginfo;
+    reginfo.name = "esp";
+    m_reg_map[k_machine_esp] = reginfo;
+    reginfo.name = "esi";
+    m_reg_map[k_machine_esi] = reginfo;
+    reginfo.name = "eip";
+    m_reg_map[k_machine_eip] = reginfo;
+    reginfo.name = "ecx";
+    m_reg_map[k_machine_ecx] = reginfo;
+    reginfo.name = "ebx";
+    m_reg_map[k_machine_ebx] = reginfo;
+    reginfo.name = "ebp";
+    m_reg_map[k_machine_ebp] = reginfo;
+    reginfo.name = "edi";
+    m_reg_map[k_machine_edi] = reginfo;
+  } else {
+    m_machine_ip_regnum = k_machine_rip;
+    m_machine_sp_regnum = k_machine_rsp;
+    m_machine_fp_regnum = k_machine_rbp;
+    m_wordsize = 8;
+
+    struct lldb_reg_info reginfo;
+    reginfo.name = "rax";
+    m_reg_map[k_machine_rax] = reginfo;
+    reginfo.name = "rdx";
+    m_reg_map[k_machine_rdx] = reginfo;
+    reginfo.name = "rsp";
+    m_reg_map[k_machine_rsp] = reginfo;
+    reginfo.name = "rsi";
+    m_reg_map[k_machine_rsi] = reginfo;
+    reginfo.name = "r8";
+    m_reg_map[k_machine_r8] = reginfo;
+    reginfo.name = "r10";
+    m_reg_map[k_machine_r10] = reginfo;
+    reginfo.name = "r12";
+    m_reg_map[k_machine_r12] = reginfo;
+    reginfo.name = "r14";
+    m_reg_map[k_machine_r14] = reginfo;
+    reginfo.name = "rip";
+    m_reg_map[k_machine_rip] = reginfo;
+    reginfo.name = "rcx";
+    m_reg_map[k_machine_rcx] = reginfo;
+    reginfo.name = "rbx";
+    m_reg_map[k_machine_rbx] = reginfo;
+    reginfo.name = "rbp";
+    m_reg_map[k_machine_rbp] = reginfo;
+    reginfo.name = "rdi";
+    m_reg_map[k_machine_rdi] = reginfo;
+    reginfo.name = "r9";
+    m_reg_map[k_machine_r9] = reginfo;
+    reginfo.name = "r11";
+    m_reg_map[k_machine_r11] = reginfo;
+    reginfo.name = "r13";
+    m_reg_map[k_machine_r13] = reginfo;
+    reginfo.name = "r15";
+    m_reg_map[k_machine_r15] = reginfo;
+  }
+
+  for (MachineRegnumToNameAndLLDBRegnum::iterator it = m_reg_map.begin();
+       it != m_reg_map.end(); ++it) {
+    for (size_t i = 0; i < reg_info.size(); ++i) {
+      if (::strcmp(reg_info[i].name, it->second.name) == 0) {
+        it->second.lldb_regnum = reg_info[i].lldb_regnum;
+        break;
+      }
+    }
+  }
+
+  uint32_t lldb_regno;
+  if (machine_regno_to_lldb_regno(m_machine_sp_regnum, lldb_regno))
+    m_lldb_sp_regnum = lldb_regno;
+  if (machine_regno_to_lldb_regno(m_machine_fp_regnum, lldb_regno))
+    m_lldb_fp_regnum = lldb_regno;
+  if (machine_regno_to_lldb_regno(m_machine_ip_regnum, lldb_regno))
+    m_lldb_ip_regnum = lldb_regno;
+
+  m_register_map_initialized = true;
+}
+
+// This function expects an x86 native register number (i.e. the bits stripped
+// out of the
+// actual instruction), not an lldb register number.
+//
+// FIXME: This is ABI dependent, it shouldn't be hardcoded here.
+
+bool x86AssemblyInspectionEngine::nonvolatile_reg_p(int machine_regno) {
+  if (m_cpu == k_i386) {
+    switch (machine_regno) {
+    case k_machine_ebx:
+    case k_machine_ebp: // not actually a nonvolatile but often treated as such
+                        // by convention
+    case k_machine_esi:
+    case k_machine_edi:
+    case k_machine_esp:
+      return true;
+    default:
+      return false;
+    }
+  }
+  if (m_cpu == k_x86_64) {
+    switch (machine_regno) {
+    case k_machine_rbx:
+    case k_machine_rsp:
+    case k_machine_rbp: // not actually a nonvolatile but often treated as such
+                        // by convention
+    case k_machine_r12:
+    case k_machine_r13:
+    case k_machine_r14:
+    case k_machine_r15:
+      return true;
+    default:
+      return false;
+    }
+  }
+  return false;
+}
+
+// Macro to detect if this is a REX mode prefix byte.
+#define REX_W_PREFIX_P(opcode) (((opcode) & (~0x5)) == 0x48)
+
+// The high bit which should be added to the source register number (the "R"
+// bit)
+#define REX_W_SRCREG(opcode) (((opcode)&0x4) >> 2)
+
+// The high bit which should be added to the destination register number (the
+// "B" bit)
+#define REX_W_DSTREG(opcode) ((opcode)&0x1)
+
+// pushq %rbp [0x55]
+bool x86AssemblyInspectionEngine::push_rbp_pattern_p() {
+  uint8_t *p = m_cur_insn;
+  if (*p == 0x55)
+    return true;
+  return false;
+}
+
+// pushq $0 ; the first instruction in start() [0x6a 0x00]
+bool x86AssemblyInspectionEngine::push_0_pattern_p() {
+  uint8_t *p = m_cur_insn;
+  if (*p == 0x6a && *(p + 1) == 0x0)
+    return true;
+  return false;
+}
+
+// pushq $0
+// pushl $0
+bool x86AssemblyInspectionEngine::push_imm_pattern_p() {
+  uint8_t *p = m_cur_insn;
+  if (*p == 0x68 || *p == 0x6a)
+    return true;
+  return false;
+}
+
+// movq %rsp, %rbp [0x48 0x8b 0xec] or [0x48 0x89 0xe5]
+// movl %esp, %ebp [0x8b 0xec] or [0x89 0xe5]
+bool x86AssemblyInspectionEngine::mov_rsp_rbp_pattern_p() {
+  uint8_t *p = m_cur_insn;
+  if (m_wordsize == 8 && *p == 0x48)
+    p++;
+  if (*(p) == 0x8b && *(p + 1) == 0xec)
+    return true;
+  if (*(p) == 0x89 && *(p + 1) == 0xe5)
+    return true;
+  return false;
+}
+
+// subq $0x20, %rsp
+bool x86AssemblyInspectionEngine::sub_rsp_pattern_p(int &amount) {
+  uint8_t *p = m_cur_insn;
+  if (m_wordsize == 8 && *p == 0x48)
+    p++;
+  // 8-bit immediate operand
+  if (*p == 0x83 && *(p + 1) == 0xec) {
+    amount = (int8_t) * (p + 2);
+    return true;
+  }
+  // 32-bit immediate operand
+  if (*p == 0x81 && *(p + 1) == 0xec) {
+    amount = (int32_t)extract_4(p + 2);
+    return true;
+  }
+  return false;
+}
+
+// addq $0x20, %rsp
+bool x86AssemblyInspectionEngine::add_rsp_pattern_p(int &amount) {
+  uint8_t *p = m_cur_insn;
+  if (m_wordsize == 8 && *p == 0x48)
+    p++;
+  // 8-bit immediate operand
+  if (*p == 0x83 && *(p + 1) == 0xc4) {
+    amount = (int8_t) * (p + 2);
+    return true;
+  }
+  // 32-bit immediate operand
+  if (*p == 0x81 && *(p + 1) == 0xc4) {
+    amount = (int32_t)extract_4(p + 2);
+    return true;
+  }
+  return false;
+}
+
+// lea esp, [esp - 0x28]
+// lea esp, [esp + 0x28]
+bool x86AssemblyInspectionEngine::lea_rsp_pattern_p(int &amount) {
+  uint8_t *p = m_cur_insn;
+  if (m_wordsize == 8 && *p == 0x48)
+    p++;
+
+  // Check opcode
+  if (*p != 0x8d)
+    return false;
+
+  // 8 bit displacement
+  if (*(p + 1) == 0x64 && (*(p + 2) & 0x3f) == 0x24) {
+    amount = (int8_t) * (p + 3);
+    return true;
+  }
+
+  // 32 bit displacement
+  if (*(p + 1) == 0xa4 && (*(p + 2) & 0x3f) == 0x24) {
+    amount = (int32_t)extract_4(p + 3);
+    return true;
+  }
+
+  return false;
+}
+
+// pushq %rbx
+// pushl %ebx
+bool x86AssemblyInspectionEngine::push_reg_p(int &regno) {
+  uint8_t *p = m_cur_insn;
+  int regno_prefix_bit = 0;
+  // If we have a rex prefix byte, check to see if a B bit is set
+  if (m_wordsize == 8 && *p == 0x41) {
+    regno_prefix_bit = 1 << 3;
+    p++;
+  }
+  if (*p >= 0x50 && *p <= 0x57) {
+    regno = (*p - 0x50) | regno_prefix_bit;
+    return true;
+  }
+  return false;
+}
+
+// popq %rbx
+// popl %ebx
+bool x86AssemblyInspectionEngine::pop_reg_p(int &regno) {
+  uint8_t *p = m_cur_insn;
+  int regno_prefix_bit = 0;
+  // If we have a rex prefix byte, check to see if a B bit is set
+  if (m_wordsize == 8 && *p == 0x41) {
+    regno_prefix_bit = 1 << 3;
+    p++;
+  }
+  if (*p >= 0x58 && *p <= 0x5f) {
+    regno = (*p - 0x58) | regno_prefix_bit;
+    return true;
+  }
+  return false;
+}
+
+// popq %rbp [0x5d]
+// popl %ebp [0x5d]
+bool x86AssemblyInspectionEngine::pop_rbp_pattern_p() {
+  uint8_t *p = m_cur_insn;
+  return (*p == 0x5d);
+}
+
+// leave [0xc9]
+bool x86AssemblyInspectionEngine::leave_pattern_p() {
+  uint8_t *p = m_cur_insn;
+  return (*p == 0xc9);
+}
+
+// call $0 [0xe8 0x0 0x0 0x0 0x0]
+bool x86AssemblyInspectionEngine::call_next_insn_pattern_p() {
+  uint8_t *p = m_cur_insn;
+  return (*p == 0xe8) && (*(p + 1) == 0x0) && (*(p + 2) == 0x0) &&
+         (*(p + 3) == 0x0) && (*(p + 4) == 0x0);
+}
+
+// Look for an instruction sequence storing a nonvolatile register
+// on to the stack frame.
+
+//  movq %rax, -0x10(%rbp) [0x48 0x89 0x45 0xf0]
+//  movl %eax, -0xc(%ebp)  [0x89 0x45 0xf4]
+
+// The offset value returned in rbp_offset will be positive --
+// but it must be subtraced from the frame base register to get
+// the actual location.  The positive value returned for the offset
+// is a convention used elsewhere for CFA offsets et al.
+
+bool x86AssemblyInspectionEngine::mov_reg_to_local_stack_frame_p(
+    int &regno, int &rbp_offset) {
+  uint8_t *p = m_cur_insn;
+  int src_reg_prefix_bit = 0;
+  int target_reg_prefix_bit = 0;
+
+  if (m_wordsize == 8 && REX_W_PREFIX_P(*p)) {
+    src_reg_prefix_bit = REX_W_SRCREG(*p) << 3;
+    target_reg_prefix_bit = REX_W_DSTREG(*p) << 3;
+    if (target_reg_prefix_bit == 1) {
+      // rbp/ebp don't need a prefix bit - we know this isn't the
+      // reg we care about.
+      return false;
+    }
+    p++;
+  }
+
+  if (*p == 0x89) {
+    /* Mask off the 3-5 bits which indicate the destination register
+       if this is a ModR/M byte.  */
+    int opcode_destreg_masked_out = *(p + 1) & (~0x38);
+
+    /* Is this a ModR/M byte with Mod bits 01 and R/M bits 101
+       and three bits between them, e.g. 01nnn101
+       We're looking for a destination of ebp-disp8 or ebp-disp32.   */
+    int immsize;
+    if (opcode_destreg_masked_out == 0x45)
+      immsize = 2;
+    else if (opcode_destreg_masked_out == 0x85)
+      immsize = 4;
+    else
+      return false;
+
+    int offset = 0;
+    if (immsize == 2)
+      offset = (int8_t) * (p + 2);
+    if (immsize == 4)
+      offset = (uint32_t)extract_4(p + 2);
+    if (offset > 0)
+      return false;
+
+    regno = ((*(p + 1) >> 3) & 0x7) | src_reg_prefix_bit;
+    rbp_offset = offset > 0 ? offset : -offset;
+    return true;
+  }
+  return false;
+}
+
+// ret [0xc9] or [0xc2 imm8] or [0xca imm8]
+bool x86AssemblyInspectionEngine::ret_pattern_p() {
+  uint8_t *p = m_cur_insn;
+  if (*p == 0xc9 || *p == 0xc2 || *p == 0xca || *p == 0xc3)
+    return true;
+  return false;
+}
+
+uint32_t x86AssemblyInspectionEngine::extract_4(uint8_t *b) {
+  uint32_t v = 0;
+  for (int i = 3; i >= 0; i--)
+    v = (v << 8) | b[i];
+  return v;
+}
+
+bool x86AssemblyInspectionEngine::instruction_length(uint8_t *insn_p,
+                                                     int &length) {
+
+  const uint32_t max_op_byte_size = m_arch.GetMaximumOpcodeByteSize();
+  llvm::SmallVector<uint8_t, 32> opcode_data;
+  opcode_data.resize(max_op_byte_size);
+
+  char out_string[512];
+  const size_t inst_size =
+      ::LLVMDisasmInstruction(m_disasm_context, insn_p, max_op_byte_size, 0,
+                              out_string, sizeof(out_string));
+
+  length = inst_size;
+  return true;
+}
+
+bool x86AssemblyInspectionEngine::machine_regno_to_lldb_regno(
+    int machine_regno, uint32_t &lldb_regno) {
+  MachineRegnumToNameAndLLDBRegnum::iterator it = m_reg_map.find(machine_regno);
+  if (it != m_reg_map.end()) {
+    lldb_regno = it->second.lldb_regnum;
+    return true;
+  }
+  return false;
+  return false;
+}
+
+bool x86AssemblyInspectionEngine::GetNonCallSiteUnwindPlanFromAssembly(
+    uint8_t *data, size_t size, AddressRange &func_range,
+    UnwindPlan &unwind_plan) {
+  unwind_plan.Clear();
+
+  if (data == nullptr || size == 0)
+    return false;
+
+  if (m_register_map_initialized == false)
+    return false;
+
+  addr_t current_func_text_offset = 0;
+  int current_sp_bytes_offset_from_cfa = 0;
+  UnwindPlan::Row::RegisterLocation initial_regloc;
+  UnwindPlan::RowSP row(new UnwindPlan::Row);
+
+  unwind_plan.SetPlanValidAddressRange(func_range);
+  unwind_plan.SetRegisterKind(eRegisterKindLLDB);
+
+  // At the start of the function, find the CFA by adding wordsize to the SP
+  // register
+  row->SetOffset(current_func_text_offset);
+  row->GetCFAValue().SetIsRegisterPlusOffset(m_lldb_sp_regnum, m_wordsize);
+
+  // caller's stack pointer value before the call insn is the CFA address
+  initial_regloc.SetIsCFAPlusOffset(0);
+  row->SetRegisterInfo(m_lldb_sp_regnum, initial_regloc);
+
+  // saved instruction pointer can be found at CFA - wordsize.
+  current_sp_bytes_offset_from_cfa = m_wordsize;
+  initial_regloc.SetAtCFAPlusOffset(-current_sp_bytes_offset_from_cfa);
+  row->SetRegisterInfo(m_lldb_ip_regnum, initial_regloc);
+
+  unwind_plan.AppendRow(row);
+
+  // Allocate a new Row, populate it with the existing Row contents.
+  UnwindPlan::Row *newrow = new UnwindPlan::Row;
+  *newrow = *row.get();
+  row.reset(newrow);
+
+  // Track which registers have been saved so far in the prologue.
+  // If we see another push of that register, it's not part of the prologue.
+  // The register numbers used here are the machine register #'s
+  // (i386_register_numbers, x86_64_register_numbers).
+  std::vector<bool> saved_registers(32, false);
+
+  // Once the prologue has completed we'll save a copy of the unwind
+  // instructions
+  // If there is an epilogue in the middle of the function, after that epilogue
+  // we'll reinstate
+  // the unwind setup -- we assume that some code path jumps over the
+  // mid-function epilogue
+
+  UnwindPlan::RowSP prologue_completed_row; // copy of prologue row of CFI
+  int prologue_completed_sp_bytes_offset_from_cfa; // The sp value before the
+                                                   // epilogue started executed
+  std::vector<bool> prologue_completed_saved_registers;
+
+  while (current_func_text_offset < size) {
+    int stack_offset, insn_len;
+    int machine_regno;   // register numbers masked directly out of instructions
+    uint32_t lldb_regno; // register numbers in lldb's eRegisterKindLLDB
+                         // numbering scheme
+
+    bool in_epilogue = false; // we're in the middle of an epilogue sequence
+    bool row_updated = false; // The UnwindPlan::Row 'row' has been updated
+
+    m_cur_insn = data + current_func_text_offset;
+    if (!instruction_length(m_cur_insn, insn_len) || insn_len == 0 ||
+        insn_len > kMaxInstructionByteSize) {
+      // An unrecognized/junk instruction
+      break;
+    }
+
+    if (push_rbp_pattern_p()) {
+      current_sp_bytes_offset_from_cfa += m_wordsize;
+      row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
+      UnwindPlan::Row::RegisterLocation regloc;
+      regloc.SetAtCFAPlusOffset(-row->GetCFAValue().GetOffset());
+      row->SetRegisterInfo(m_lldb_fp_regnum, regloc);
+      saved_registers[m_machine_fp_regnum] = true;
+      row_updated = true;
+    }
+
+    else if (mov_rsp_rbp_pattern_p()) {
+      row->GetCFAValue().SetIsRegisterPlusOffset(
+          m_lldb_fp_regnum, row->GetCFAValue().GetOffset());
+      row_updated = true;
+    }
+
+    // This is the start() function (or a pthread equivalent), it starts with a
+    // pushl $0x0 which puts the
+    // saved pc value of 0 on the stack.  In this case we want to pretend we
+    // didn't see a stack movement at all --
+    // normally the saved pc value is already on the stack by the time the
+    // function starts executing.
+    else if (push_0_pattern_p()) {
+    }
+
+    else if (push_reg_p(machine_regno)) {
+      current_sp_bytes_offset_from_cfa += m_wordsize;
+      // the PUSH instruction has moved the stack pointer - if the CFA is set in
+      // terms of the stack pointer,
+      // we need to add a new row of instructions.
+      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
+        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
+        row_updated = true;
+      }
+      // record where non-volatile (callee-saved, spilled) registers are saved
+      // on the stack
+      if (nonvolatile_reg_p(machine_regno) &&
+          machine_regno_to_lldb_regno(machine_regno, lldb_regno) &&
+          saved_registers[machine_regno] == false) {
+        UnwindPlan::Row::RegisterLocation regloc;
+        regloc.SetAtCFAPlusOffset(-current_sp_bytes_offset_from_cfa);
+        row->SetRegisterInfo(lldb_regno, regloc);
+        saved_registers[machine_regno] = true;
+        row_updated = true;
+      }
+    }
+
+    else if (pop_reg_p(machine_regno)) {
+      current_sp_bytes_offset_from_cfa -= m_wordsize;
+
+      if (nonvolatile_reg_p(machine_regno) &&
+          machine_regno_to_lldb_regno(machine_regno, lldb_regno) &&
+          saved_registers[machine_regno] == true) {
+        saved_registers[machine_regno] = false;
+        row->RemoveRegisterInfo(lldb_regno);
+
+        if (machine_regno == (int)m_machine_fp_regnum) {
+          row->GetCFAValue().SetIsRegisterPlusOffset(
+              m_lldb_sp_regnum, row->GetCFAValue().GetOffset());
+        }
+
+        in_epilogue = true;
+        row_updated = true;
+      }
+
+      // the POP instruction has moved the stack pointer - if the CFA is set in
+      // terms of the stack pointer,
+      // we need to add a new row of instructions.
+      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
+        row->GetCFAValue().SetIsRegisterPlusOffset(
+            m_lldb_sp_regnum, current_sp_bytes_offset_from_cfa);
+        row_updated = true;
+      }
+    }
+
+    // The LEAVE instruction moves the value from rbp into rsp and pops
+    // a value off the stack into rbp (restoring the caller's rbp value).
+    // It is the opposite of ENTER, or 'push rbp, mov rsp rbp'.
+    else if (leave_pattern_p()) {
+      // We're going to copy the value in rbp into rsp, so re-set the sp offset
+      // based on the CFAValue.  Also, adjust it to recognize that we're popping
+      // the saved rbp value off the stack.
+      current_sp_bytes_offset_from_cfa = row->GetCFAValue().GetOffset();
+      current_sp_bytes_offset_from_cfa -= m_wordsize;
+      row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
+
+      // rbp is restored to the caller's value
+      saved_registers[m_machine_fp_regnum] = false;
+      row->RemoveRegisterInfo(m_lldb_fp_regnum);
+
+      // cfa is now in terms of rsp again.
+      row->GetCFAValue().SetIsRegisterPlusOffset(
+          m_lldb_sp_regnum, row->GetCFAValue().GetOffset());
+      row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
+
+      in_epilogue = true;
+      row_updated = true;
+    }
+
+    else if (mov_reg_to_local_stack_frame_p(machine_regno, stack_offset) &&
+             nonvolatile_reg_p(machine_regno) &&
+             machine_regno_to_lldb_regno(machine_regno, lldb_regno) &&
+             saved_registers[machine_regno] == false) {
+      saved_registers[machine_regno] = true;
+
+      UnwindPlan::Row::RegisterLocation regloc;
+
+      // stack_offset for 'movq %r15, -80(%rbp)' will be 80.
+      // In the Row, we want to express this as the offset from the CFA.  If the
+      // frame base
+      // is rbp (like the above instruction), the CFA offset for rbp is probably
+      // 16.  So we
+      // want to say that the value is stored at the CFA address - 96.
+      regloc.SetAtCFAPlusOffset(
+          -(stack_offset + row->GetCFAValue().GetOffset()));
+
+      row->SetRegisterInfo(lldb_regno, regloc);
+
+      row_updated = true;
+    }
+
+    else if (sub_rsp_pattern_p(stack_offset)) {
+      current_sp_bytes_offset_from_cfa += stack_offset;
+      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
+        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
+        row_updated = true;
+      }
+    }
+
+    else if (add_rsp_pattern_p(stack_offset)) {
+      current_sp_bytes_offset_from_cfa -= stack_offset;
+      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
+        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
+        row_updated = true;
+      }
+      in_epilogue = true;
+    }
+
+    else if (lea_rsp_pattern_p(stack_offset)) {
+      current_sp_bytes_offset_from_cfa -= stack_offset;
+      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
+        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
+        row_updated = true;
+      }
+      if (stack_offset > 0)
+        in_epilogue = true;
+    }
+
+    else if (ret_pattern_p() && prologue_completed_row.get()) {
+      // Reinstate the saved prologue setup for any instructions
+      // that come after the ret instruction
+
+      UnwindPlan::Row *newrow = new UnwindPlan::Row;
+      *newrow = *prologue_completed_row.get();
+      row.reset(newrow);
+      current_sp_bytes_offset_from_cfa =
+          prologue_completed_sp_bytes_offset_from_cfa;
+
+      saved_registers.clear();
+      saved_registers.resize(prologue_completed_saved_registers.size(), false);
+      for (size_t i = 0; i < prologue_completed_saved_registers.size(); ++i) {
+        saved_registers[i] = prologue_completed_saved_registers[i];
+      }
+
+      in_epilogue = true;
+      row_updated = true;
+    }
+
+    // call next instruction
+    //     call 0
+    //  => pop  %ebx
+    // This is used in i386 programs to get the PIC base address for finding
+    // global data
+    else if (call_next_insn_pattern_p()) {
+      current_sp_bytes_offset_from_cfa += m_wordsize;
+      if (row->GetCFAValue().GetRegisterNumber() == m_lldb_sp_regnum) {
+        row->GetCFAValue().SetOffset(current_sp_bytes_offset_from_cfa);
+        row_updated = true;
+      }
+    }
+
+    if (row_updated) {
+      if (current_func_text_offset + insn_len < size) {
+        row->SetOffset(current_func_text_offset + insn_len);
+        unwind_plan.AppendRow(row);
+        // Allocate a new Row, populate it with the existing Row contents.
+        newrow = new UnwindPlan::Row;
+        *newrow = *row.get();
+        row.reset(newrow);
+      }
+    }
+
+    if (in_epilogue == false && row_updated) {
+      // If we're not in an epilogue sequence, save the updated Row
+      UnwindPlan::Row *newrow = new UnwindPlan::Row;
+      *newrow = *row.get();
+      prologue_completed_row.reset(newrow);
+
+      prologue_completed_saved_registers.clear();
+      prologue_completed_saved_registers.resize(saved_registers.size(), false);
+      for (size_t i = 0; i < saved_registers.size(); ++i) {
+        prologue_completed_saved_registers[i] = saved_registers[i];
+      }
+    }
+
+    // We may change the sp value without adding a new Row necessarily -- keep
+    // track of it either way.
+    if (in_epilogue == false) {
+      prologue_completed_sp_bytes_offset_from_cfa =
+          current_sp_bytes_offset_from_cfa;
+    }
+
+    m_cur_insn = m_cur_insn + insn_len;
+    current_func_text_offset += insn_len;
+  }
+
+  unwind_plan.SetSourceName("assembly insn profiling");
+  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
+
+  return true;
+}
+
+bool x86AssemblyInspectionEngine::AugmentUnwindPlanFromCallSite(
+    uint8_t *data, size_t size, AddressRange &func_range,
+    UnwindPlan &unwind_plan, RegisterContextSP &reg_ctx) {
+  Address addr_start = func_range.GetBaseAddress();
+  if (!addr_start.IsValid())
+    return false;
+
+  // We either need a live RegisterContext, or we need the UnwindPlan to already
+  // be in the lldb register numbering scheme.
+  if (reg_ctx.get() == nullptr &&
+      unwind_plan.GetRegisterKind() != eRegisterKindLLDB)
+    return false;
+
+  // Is original unwind_plan valid?
+  // unwind_plan should have at least one row which is ABI-default (CFA register
+  // is sp),
+  // and another row in mid-function.
+  if (unwind_plan.GetRowCount() < 2)
+    return false;
+
+  UnwindPlan::RowSP first_row = unwind_plan.GetRowAtIndex(0);
+  if (first_row->GetOffset() != 0)
+    return false;
+  uint32_t cfa_reg = first_row->GetCFAValue().GetRegisterNumber();
+  if (unwind_plan.GetRegisterKind() != eRegisterKindLLDB) {
+    cfa_reg = reg_ctx->ConvertRegisterKindToRegisterNumber(
+        unwind_plan.GetRegisterKind(),
+        first_row->GetCFAValue().GetRegisterNumber());
+  }
+  if (cfa_reg != m_lldb_sp_regnum ||
+      first_row->GetCFAValue().GetOffset() != m_wordsize)
+    return false;
+
+  UnwindPlan::RowSP original_last_row = unwind_plan.GetRowForFunctionOffset(-1);
+
+  size_t offset = 0;
+  int row_id = 1;
+  bool unwind_plan_updated = false;
+  UnwindPlan::RowSP row(new UnwindPlan::Row(*first_row));
+  m_cur_insn = data + offset;
+
+  // After a mid-function epilogue we will need to re-insert the original unwind
+  // rules
+  // so unwinds work for the remainder of the function.  These aren't common
+  // with clang/gcc
+  // on x86 but it is possible.
+  bool reinstate_unwind_state = false;
+
+  while (offset < size) {
+    m_cur_insn = data + offset;
+    int insn_len;
+    if (!instruction_length(m_cur_insn, insn_len) || insn_len == 0 ||
+        insn_len > kMaxInstructionByteSize) {
+      // An unrecognized/junk instruction.
+      break;
+    }
+
+    // Advance offsets.
+    offset += insn_len;
+    m_cur_insn = data + offset;
+
+    if (reinstate_unwind_state) {
+      // that was the last instruction of this function
+      if (offset >= size)
+        continue;
+
+      UnwindPlan::RowSP new_row(new UnwindPlan::Row());
+      *new_row = *original_last_row;
+      new_row->SetOffset(offset);
+      unwind_plan.AppendRow(new_row);
+      row.reset(new UnwindPlan::Row());
+      *row = *new_row;
+      reinstate_unwind_state = false;
+      unwind_plan_updated = true;
+      continue;
+    }
+
+    // If we already have one row for this instruction, we can continue.
+    while (row_id < unwind_plan.GetRowCount() &&
+           unwind_plan.GetRowAtIndex(row_id)->GetOffset() <= offset) {
+      row_id++;
+    }
+    UnwindPlan::RowSP original_row = unwind_plan.GetRowAtIndex(row_id - 1);
+    if (original_row->GetOffset() == offset) {
+      *row = *original_row;
+      continue;
+    }
+
+    if (row_id == 0) {
+      // If we are here, compiler didn't generate CFI for prologue.
+      // This won't happen to GCC or clang.
+      // In this case, bail out directly.
+      return false;
+    }
+
+    // Inspect the instruction to check if we need a new row for it.
+    cfa_reg = row->GetCFAValue().GetRegisterNumber();
+    if (unwind_plan.GetRegisterKind() != eRegisterKindLLDB) {
+      cfa_reg = reg_ctx->ConvertRegisterKindToRegisterNumber(
+          unwind_plan.GetRegisterKind(),
+          row->GetCFAValue().GetRegisterNumber());
+    }
+    if (cfa_reg == m_lldb_sp_regnum) {
+      // CFA register is sp.
+
+      // call next instruction
+      //     call 0
+      //  => pop  %ebx
+      if (call_next_insn_pattern_p()) {
+        row->SetOffset(offset);
+        row->GetCFAValue().IncOffset(m_wordsize);
+
+        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
+        unwind_plan.InsertRow(new_row);
+        unwind_plan_updated = true;
+        continue;
+      }
+
+      // push/pop register
+      int regno;
+      if (push_reg_p(regno)) {
+        row->SetOffset(offset);
+        row->GetCFAValue().IncOffset(m_wordsize);
+
+        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
+        unwind_plan.InsertRow(new_row);
+        unwind_plan_updated = true;
+        continue;
+      }
+      if (pop_reg_p(regno)) {
+        // Technically, this might be a nonvolatile register recover in
+        // epilogue.
+        // We should reset RegisterInfo for the register.
+        // But in practice, previous rule for the register is still valid...
+        // So we ignore this case.
+
+        row->SetOffset(offset);
+        row->GetCFAValue().IncOffset(-m_wordsize);
+
+        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
+        unwind_plan.InsertRow(new_row);
+        unwind_plan_updated = true;
+        continue;
+      }
+
+      // push imm
+      if (push_imm_pattern_p()) {
+        row->SetOffset(offset);
+        row->GetCFAValue().IncOffset(m_wordsize);
+        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
+        unwind_plan.InsertRow(new_row);
+        unwind_plan_updated = true;
+        continue;
+      }
+
+      // add/sub %rsp/%esp
+      int amount;
+      if (add_rsp_pattern_p(amount)) {
+        row->SetOffset(offset);
+        row->GetCFAValue().IncOffset(-amount);
+
+        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
+        unwind_plan.InsertRow(new_row);
+        unwind_plan_updated = true;
+        continue;
+      }
+      if (sub_rsp_pattern_p(amount)) {
+        row->SetOffset(offset);
+        row->GetCFAValue().IncOffset(amount);
+
+        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
+        unwind_plan.InsertRow(new_row);
+        unwind_plan_updated = true;
+        continue;
+      }
+
+      // lea %rsp, [%rsp + $offset]
+      if (lea_rsp_pattern_p(amount)) {
+        row->SetOffset(offset);
+        row->GetCFAValue().IncOffset(-amount);
+
+        UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
+        unwind_plan.InsertRow(new_row);
+        unwind_plan_updated = true;
+        continue;
+      }
+
+      if (ret_pattern_p()) {
+        reinstate_unwind_state = true;
+        continue;
+      }
+    } else if (cfa_reg == m_lldb_fp_regnum) {
+      // CFA register is fp.
+
+      // The only case we care about is epilogue:
+      //     [0x5d] pop %rbp/%ebp
+      //  => [0xc3] ret
+      if (pop_rbp_pattern_p() || leave_pattern_p()) {
+          offset += 1;
+          row->SetOffset(offset);
+          row->GetCFAValue().SetIsRegisterPlusOffset(
+              first_row->GetCFAValue().GetRegisterNumber(), m_wordsize);
+
+          UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
+          unwind_plan.InsertRow(new_row);
+          unwind_plan_updated = true;
+          reinstate_unwind_state = true;
+          continue;
+      }
+    } else {
+      // CFA register is not sp or fp.
+
+      // This must be hand-written assembly.
+      // Just trust eh_frame and assume we have finished.
+      break;
+    }
+  }
+
+  unwind_plan.SetPlanValidAddressRange(func_range);
+  if (unwind_plan_updated) {
+    std::string unwind_plan_source(unwind_plan.GetSourceName().AsCString());
+    unwind_plan_source += " plus augmentation from assembly parsing";
+    unwind_plan.SetSourceName(unwind_plan_source.c_str());
+    unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
+    unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
+  }
+  return true;
+}
+
+bool x86AssemblyInspectionEngine::FindFirstNonPrologueInstruction(
+    uint8_t *data, size_t size, size_t &offset) {
+  offset = 0;
+
+  if (m_register_map_initialized == false)
+    return false;
+
+  while (offset < size) {
+    int regno;
+    int insn_len;
+    int scratch;
+
+    m_cur_insn = data + offset;
+    if (!instruction_length(m_cur_insn, insn_len) ||
+        insn_len > kMaxInstructionByteSize || insn_len == 0) {
+      // An error parsing the instruction, i.e. probably data/garbage - stop
+      // scanning
+      break;
+    }
+
+    if (push_rbp_pattern_p() || mov_rsp_rbp_pattern_p() ||
+        sub_rsp_pattern_p(scratch) || push_reg_p(regno) ||
+        mov_reg_to_local_stack_frame_p(regno, scratch) ||
+        (lea_rsp_pattern_p(scratch) && offset == 0)) {
+      offset += insn_len;
+      continue;
+    }
+    //
+    // Unknown non-prologue instruction - stop scanning
+    break;
+  }
+
+  return true;
+}
diff --git a/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.h b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.h
new file mode 100644
index 0000000..9ed7938
--- /dev/null
+++ b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.h
@@ -0,0 +1,178 @@
+//===-- x86AssemblyInspectionEngine.h ---------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef liblldb_x86AssemblyInspectionEngine_h_
+#define liblldb_x86AssemblyInspectionEngine_h_
+
+#include "llvm-c/Disassembler.h"
+
+#include "lldb/lldb-enumerations.h"
+#include "lldb/lldb-forward.h"
+#include "lldb/lldb-private.h"
+
+#include "lldb/Core/ArchSpec.h"
+#include "lldb/Core/ConstString.h"
+
+#include <map>
+#include <vector>
+
+namespace lldb_private {
+
+// x86AssemblyInspectionEngine - a class which will take a buffer of bytes
+// of i386/x86_64 instructions and create an UnwindPlan based on those
+// assembly instructions.
+class x86AssemblyInspectionEngine {
+
+public:
+  /// default ctor
+  x86AssemblyInspectionEngine(const lldb_private::ArchSpec &arch);
+
+  /// default dtor
+  ~x86AssemblyInspectionEngine();
+
+  /// One of the two initialize methods that can be called on this object;
+  /// they must be called before any of the assembly inspection methods
+  /// are called.  This one should be used if the caller has access to a
+  /// valid RegisterContext.
+  void Initialize(lldb::RegisterContextSP &reg_ctx);
+
+  /// One of the two initialize methods that can be called on this object;
+  /// they must be called before any of the assembly inspection methods
+  /// are called.  This one takes a vector of register name and lldb
+  /// register numbers.
+  struct lldb_reg_info {
+    const char *name;
+    uint32_t lldb_regnum;
+    lldb_reg_info() : name(nullptr), lldb_regnum(LLDB_INVALID_REGNUM) {}
+  };
+  void Initialize(std::vector<lldb_reg_info> &reg_info);
+
+  /// Create an UnwindPlan for a "non-call site" stack frame situation.
+  /// This is usually when this function/method is currently executing, and may
+  /// be at
+  /// a location where exception-handling style unwind information (eh_frame,
+  /// compact unwind info, arm unwind info)
+  /// are not valid.
+  /// \p data is a pointer to the instructions for the function
+  /// \p size is the size of the instruction buffer above
+  /// \p func_range is the start Address and size of the function, to be
+  /// included in the UnwindPlan
+  /// \p unwind_plan is the unwind plan that this method creates
+  /// \returns true if it was able to create an UnwindPlan; false if not.
+  bool
+  GetNonCallSiteUnwindPlanFromAssembly(uint8_t *data, size_t size,
+                                       lldb_private::AddressRange &func_range,
+                                       lldb_private::UnwindPlan &unwind_plan);
+
+  /// Take an existing UnwindPlan, probably from eh_frame which may be missing
+  /// description
+  /// of the epilogue instructions, and add the epilogue description to it based
+  /// on the
+  /// instructions in the function.
+  ///
+  /// The \p unwind_plan 's register numbers must be converted into the lldb
+  /// register numbering
+  /// scheme OR a RegisterContext must be provided in \p reg_ctx.  If the \p
+  /// unwind_plan
+  /// register numbers are already in lldb register numbering, \p reg_ctx may be
+  /// null.
+  /// \returns true if the \p unwind_plan was updated, false if it was not.
+  bool AugmentUnwindPlanFromCallSite(uint8_t *data, size_t size,
+                                     lldb_private::AddressRange &func_range,
+                                     lldb_private::UnwindPlan &unwind_plan,
+                                     lldb::RegisterContextSP &reg_ctx);
+
+  bool FindFirstNonPrologueInstruction(uint8_t *data, size_t size,
+                                       size_t &offset);
+
+private:
+  bool nonvolatile_reg_p(int machine_regno);
+  bool push_rbp_pattern_p();
+  bool push_0_pattern_p();
+  bool push_imm_pattern_p();
+  bool mov_rsp_rbp_pattern_p();
+  bool sub_rsp_pattern_p(int &amount);
+  bool add_rsp_pattern_p(int &amount);
+  bool lea_rsp_pattern_p(int &amount);
+  bool push_reg_p(int &regno);
+  bool pop_reg_p(int &regno);
+  bool pop_rbp_pattern_p();
+  bool leave_pattern_p();
+  bool call_next_insn_pattern_p();
+  bool mov_reg_to_local_stack_frame_p(int &regno, int &rbp_offset);
+  bool ret_pattern_p();
+  uint32_t extract_4(uint8_t *b);
+
+  bool instruction_length(uint8_t *insn, int &length);
+
+  bool machine_regno_to_lldb_regno(int machine_regno, uint32_t &lldb_regno);
+
+  enum CPU { k_i386, k_x86_64, k_cpu_unspecified };
+
+  enum i386_register_numbers {
+    k_machine_eax = 0,
+    k_machine_ecx = 1,
+    k_machine_edx = 2,
+    k_machine_ebx = 3,
+    k_machine_esp = 4,
+    k_machine_ebp = 5,
+    k_machine_esi = 6,
+    k_machine_edi = 7,
+    k_machine_eip = 8
+  };
+
+  enum x86_64_register_numbers {
+    k_machine_rax = 0,
+    k_machine_rcx = 1,
+    k_machine_rdx = 2,
+    k_machine_rbx = 3,
+    k_machine_rsp = 4,
+    k_machine_rbp = 5,
+    k_machine_rsi = 6,
+    k_machine_rdi = 7,
+    k_machine_r8 = 8,
+    k_machine_r9 = 9,
+    k_machine_r10 = 10,
+    k_machine_r11 = 11,
+    k_machine_r12 = 12,
+    k_machine_r13 = 13,
+    k_machine_r14 = 14,
+    k_machine_r15 = 15,
+    k_machine_rip = 16
+  };
+
+  enum { kMaxInstructionByteSize = 32 };
+
+  uint8_t *m_cur_insn;
+
+  uint32_t m_machine_ip_regnum;
+  uint32_t m_machine_sp_regnum;
+  uint32_t m_machine_fp_regnum;
+  uint32_t m_lldb_ip_regnum;
+  uint32_t m_lldb_sp_regnum;
+  uint32_t m_lldb_fp_regnum;
+
+  typedef std::map<uint32_t, lldb_reg_info> MachineRegnumToNameAndLLDBRegnum;
+
+  MachineRegnumToNameAndLLDBRegnum m_reg_map;
+
+  lldb_private::ArchSpec m_arch;
+  CPU m_cpu;
+  int m_wordsize;
+
+  bool m_register_map_initialized;
+
+  ::LLVMDisasmContextRef m_disasm_context;
+
+  DISALLOW_COPY_AND_ASSIGN(x86AssemblyInspectionEngine);
+};
+
+} // namespace lldb_private
+
+#endif // liblldb_x86AssemblyInspectionEngine_h_