Import LLVM libunwind snapshot revision 246528vendor/llvm-libunwind/libunwind-r246528

From https://llvm.org/svn/llvm-project/libunwind/trunk/

1 files changed, 1009 insertions, 0 deletions

diff --git a/src/Unwind-EHABI.cpp b/src/Unwind-EHABI.cpp
new file mode 100644
index 000000000000..bc3df41f35f7
--- /dev/null
+++ b/src/Unwind-EHABI.cpp
@@ -0,0 +1,1009 @@
+//===--------------------------- Unwind-EHABI.cpp -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//
+//  Implements ARM zero-cost C++ exceptions
+//
+//===----------------------------------------------------------------------===//
+
+#include "Unwind-EHABI.h"
+
+#if _LIBUNWIND_ARM_EHABI
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <type_traits>
+
+#include "config.h"
+#include "libunwind.h"
+#include "libunwind_ext.h"
+#include "unwind.h"
+
+namespace {
+
+// Strange order: take words in order, but inside word, take from most to least
+// signinficant byte.
+uint8_t getByte(const uint32_t* data, size_t offset) {
+  const uint8_t* byteData = reinterpret_cast<const uint8_t*>(data);
+  return byteData[(offset & ~(size_t)0x03) + (3 - (offset & (size_t)0x03))];
+}
+
+const char* getNextWord(const char* data, uint32_t* out) {
+  *out = *reinterpret_cast<const uint32_t*>(data);
+  return data + 4;
+}
+
+const char* getNextNibble(const char* data, uint32_t* out) {
+  *out = *reinterpret_cast<const uint16_t*>(data);
+  return data + 2;
+}
+
+struct Descriptor {
+  // See # 9.2
+  typedef enum {
+    SU16 = 0, // Short descriptor, 16-bit entries
+    LU16 = 1, // Long descriptor,  16-bit entries
+    LU32 = 3, // Long descriptor,  32-bit entries
+    RESERVED0 =  4, RESERVED1 =  5, RESERVED2  = 6,  RESERVED3  =  7,
+    RESERVED4 =  8, RESERVED5 =  9, RESERVED6  = 10, RESERVED7  = 11,
+    RESERVED8 = 12, RESERVED9 = 13, RESERVED10 = 14, RESERVED11 = 15
+  } Format;
+
+  // See # 9.2
+  typedef enum {
+    CLEANUP = 0x0,
+    FUNC    = 0x1,
+    CATCH   = 0x2,
+    INVALID = 0x4
+  } Kind;
+};
+
+_Unwind_Reason_Code ProcessDescriptors(
+    _Unwind_State state,
+    _Unwind_Control_Block* ucbp,
+    struct _Unwind_Context* context,
+    Descriptor::Format format,
+    const char* descriptorStart,
+    uint32_t flags) {
+
+  // EHT is inlined in the index using compact form. No descriptors. #5
+  if (flags & 0x1)
+    return _URC_CONTINUE_UNWIND;
+
+  // TODO: We should check the state here, and determine whether we need to
+  // perform phase1 or phase2 unwinding.
+  (void)state;
+
+  const char* descriptor = descriptorStart;
+  uint32_t descriptorWord;
+  getNextWord(descriptor, &descriptorWord);
+  while (descriptorWord) {
+    // Read descriptor based on # 9.2.
+    uint32_t length;
+    uint32_t offset;
+    switch (format) {
+      case Descriptor::LU32:
+        descriptor = getNextWord(descriptor, &length);
+        descriptor = getNextWord(descriptor, &offset);
+      case Descriptor::LU16:
+        descriptor = getNextNibble(descriptor, &length);
+        descriptor = getNextNibble(descriptor, &offset);
+      default:
+        assert(false);
+        return _URC_FAILURE;
+    }
+
+    // See # 9.2 table for decoding the kind of descriptor. It's a 2-bit value.
+    Descriptor::Kind kind =
+        static_cast<Descriptor::Kind>((length & 0x1) | ((offset & 0x1) << 1));
+
+    // Clear off flag from last bit.
+    length &= ~1u;
+    offset &= ~1u;
+    uintptr_t scopeStart = ucbp->pr_cache.fnstart + offset;
+    uintptr_t scopeEnd = scopeStart + length;
+    uintptr_t pc = _Unwind_GetIP(context);
+    bool isInScope = (scopeStart <= pc) && (pc < scopeEnd);
+
+    switch (kind) {
+      case Descriptor::CLEANUP: {
+        // TODO(ajwong): Handle cleanup descriptors.
+        break;
+      }
+      case Descriptor::FUNC: {
+        // TODO(ajwong): Handle function descriptors.
+        break;
+      }
+      case Descriptor::CATCH: {
+        // Catch descriptors require gobbling one more word.
+        uint32_t landing_pad;
+        descriptor = getNextWord(descriptor, &landing_pad);
+
+        if (isInScope) {
+          // TODO(ajwong): This is only phase1 compatible logic. Implement
+          // phase2.
+          landing_pad = signExtendPrel31(landing_pad & ~0x80000000);
+          if (landing_pad == 0xffffffff) {
+            return _URC_HANDLER_FOUND;
+          } else if (landing_pad == 0xfffffffe) {
+            return _URC_FAILURE;
+          } else {
+            /*
+            bool is_reference_type = landing_pad & 0x80000000;
+            void* matched_object;
+            if (__cxxabiv1::__cxa_type_match(
+                    ucbp, reinterpret_cast<const std::type_info *>(landing_pad),
+                    is_reference_type,
+                    &matched_object) != __cxxabiv1::ctm_failed)
+                return _URC_HANDLER_FOUND;
+                */
+            _LIBUNWIND_ABORT("Type matching not implemented");
+          }
+        }
+        break;
+      }
+      default:
+        _LIBUNWIND_ABORT("Invalid descriptor kind found.");
+    }
+
+    getNextWord(descriptor, &descriptorWord);
+  }
+
+  return _URC_CONTINUE_UNWIND;
+}
+
+static _Unwind_Reason_Code unwindOneFrame(_Unwind_State state,
+                                          _Unwind_Control_Block* ucbp,
+                                          struct _Unwind_Context* context) {
+  // Read the compact model EHT entry's header # 6.3
+  const uint32_t* unwindingData = ucbp->pr_cache.ehtp;
+  assert((*unwindingData & 0xf0000000) == 0x80000000 && "Must be a compact entry");
+  Descriptor::Format format =
+      static_cast<Descriptor::Format>((*unwindingData & 0x0f000000) >> 24);
+
+  const char *lsda =
+      reinterpret_cast<const char *>(_Unwind_GetLanguageSpecificData(context));
+
+  // Handle descriptors before unwinding so they are processed in the context
+  // of the correct stack frame.
+  _Unwind_Reason_Code result =
+      ProcessDescriptors(state, ucbp, context, format, lsda,
+                         ucbp->pr_cache.additional);
+
+  if (result != _URC_CONTINUE_UNWIND)
+    return result;
+
+  if (unw_step(reinterpret_cast<unw_cursor_t*>(context)) != UNW_STEP_SUCCESS)
+    return _URC_FAILURE;
+  return _URC_CONTINUE_UNWIND;
+}
+
+// Generates mask discriminator for _Unwind_VRS_Pop, e.g. for _UVRSC_CORE /
+// _UVRSD_UINT32.
+uint32_t RegisterMask(uint8_t start, uint8_t count_minus_one) {
+  return ((1U << (count_minus_one + 1)) - 1) << start;
+}
+
+// Generates mask discriminator for _Unwind_VRS_Pop, e.g. for _UVRSC_VFP /
+// _UVRSD_DOUBLE.
+uint32_t RegisterRange(uint8_t start, uint8_t count_minus_one) {
+  return ((uint32_t)start << 16) | ((uint32_t)count_minus_one + 1);
+}
+
+} // end anonymous namespace
+
+/**
+ * Decodes an EHT entry.
+ *
+ * @param data Pointer to EHT.
+ * @param[out] off Offset from return value (in bytes) to begin interpretation.
+ * @param[out] len Number of bytes in unwind code.
+ * @return Pointer to beginning of unwind code.
+ */
+extern "C" const uint32_t*
+decode_eht_entry(const uint32_t* data, size_t* off, size_t* len) {
+  if ((*data & 0x80000000) == 0) {
+    // 6.2: Generic Model
+    //
+    // EHT entry is a prel31 pointing to the PR, followed by data understood
+    // only by the personality routine. Fortunately, all existing assembler
+    // implementations, including GNU assembler, LLVM integrated assembler,
+    // and ARM assembler, assume that the unwind opcodes come after the
+    // personality rountine address.
+    *off = 1; // First byte is size data.
+    *len = (((data[1] >> 24) & 0xff) + 1) * 4;
+    data++; // Skip the first word, which is the prel31 offset.
+  } else {
+    // 6.3: ARM Compact Model
+    //
+    // EHT entries here correspond to the __aeabi_unwind_cpp_pr[012] PRs indeded
+    // by format:
+    Descriptor::Format format =
+        static_cast<Descriptor::Format>((*data & 0x0f000000) >> 24);
+    switch (format) {
+      case Descriptor::SU16:
+        *len = 4;
+        *off = 1;
+        break;
+      case Descriptor::LU16:
+      case Descriptor::LU32:
+        *len = 4 + 4 * ((*data & 0x00ff0000) >> 16);
+        *off = 2;
+        break;
+      default:
+        return nullptr;
+    }
+  }
+  return data;
+}
+
+_Unwind_Reason_Code _Unwind_VRS_Interpret(
+    _Unwind_Context* context,
+    const uint32_t* data,
+    size_t offset,
+    size_t len) {
+  bool wrotePC = false;
+  bool finish = false;
+  while (offset < len && !finish) {
+    uint8_t byte = getByte(data, offset++);
+    if ((byte & 0x80) == 0) {
+      uint32_t sp;
+      _Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32, &sp);
+      if (byte & 0x40)
+        sp -= (((uint32_t)byte & 0x3f) << 2) + 4;
+      else
+        sp += ((uint32_t)byte << 2) + 4;
+      _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32, &sp);
+    } else {
+      switch (byte & 0xf0) {
+        case 0x80: {
+          if (offset >= len)
+            return _URC_FAILURE;
+          uint32_t registers =
+              (((uint32_t)byte & 0x0f) << 12) |
+              (((uint32_t)getByte(data, offset++)) << 4);
+          if (!registers)
+            return _URC_FAILURE;
+          if (registers & (1 << 15))
+            wrotePC = true;
+          _Unwind_VRS_Pop(context, _UVRSC_CORE, registers, _UVRSD_UINT32);
+          break;
+        }
+        case 0x90: {
+          uint8_t reg = byte & 0x0f;
+          if (reg == 13 || reg == 15)
+            return _URC_FAILURE;
+          uint32_t sp;
+          _Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_R0 + reg,
+                          _UVRSD_UINT32, &sp);
+          _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32,
+                          &sp);
+          break;
+        }
+        case 0xa0: {
+          uint32_t registers = RegisterMask(4, byte & 0x07);
+          if (byte & 0x08)
+            registers |= 1 << 14;
+          _Unwind_VRS_Pop(context, _UVRSC_CORE, registers, _UVRSD_UINT32);
+          break;
+        }
+        case 0xb0: {
+          switch (byte) {
+            case 0xb0:
+              finish = true;
+              break;
+            case 0xb1: {
+              if (offset >= len)
+                return _URC_FAILURE;
+              uint8_t registers = getByte(data, offset++);
+              if (registers & 0xf0 || !registers)
+                return _URC_FAILURE;
+              _Unwind_VRS_Pop(context, _UVRSC_CORE, registers, _UVRSD_UINT32);
+              break;
+            }
+            case 0xb2: {
+              uint32_t addend = 0;
+              uint32_t shift = 0;
+              // This decodes a uleb128 value.
+              while (true) {
+                if (offset >= len)
+                  return _URC_FAILURE;
+                uint32_t v = getByte(data, offset++);
+                addend |= (v & 0x7f) << shift;
+                if ((v & 0x80) == 0)
+                  break;
+                shift += 7;
+              }
+              uint32_t sp;
+              _Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32,
+                              &sp);
+              sp += 0x204 + (addend << 2);
+              _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32,
+                              &sp);
+              break;
+            }
+            case 0xb3: {
+              uint8_t v = getByte(data, offset++);
+              _Unwind_VRS_Pop(context, _UVRSC_VFP,
+                              RegisterRange(static_cast<uint8_t>(v >> 4),
+                                            v & 0x0f), _UVRSD_VFPX);
+              break;
+            }
+            case 0xb4:
+            case 0xb5:
+            case 0xb6:
+            case 0xb7:
+              return _URC_FAILURE;
+            default:
+              _Unwind_VRS_Pop(context, _UVRSC_VFP,
+                              RegisterRange(8, byte & 0x07), _UVRSD_VFPX);
+              break;
+          }
+          break;
+        }
+        case 0xc0: {
+          switch (byte) {
+            case 0xc0:
+            case 0xc1:
+            case 0xc2:
+            case 0xc3:
+            case 0xc4:
+            case 0xc5:
+              _Unwind_VRS_Pop(context, _UVRSC_WMMXD,
+                              RegisterRange(10, byte & 0x7), _UVRSD_DOUBLE);
+              break;
+            case 0xc6: {
+              uint8_t v = getByte(data, offset++);
+              uint8_t start = static_cast<uint8_t>(v >> 4);
+              uint8_t count_minus_one = v & 0xf;
+              if (start + count_minus_one >= 16)
+                return _URC_FAILURE;
+              _Unwind_VRS_Pop(context, _UVRSC_WMMXD,
+                              RegisterRange(start, count_minus_one),
+                              _UVRSD_DOUBLE);
+              break;
+            }
+            case 0xc7: {
+              uint8_t v = getByte(data, offset++);
+              if (!v || v & 0xf0)
+                return _URC_FAILURE;
+              _Unwind_VRS_Pop(context, _UVRSC_WMMXC, v, _UVRSD_DOUBLE);
+              break;
+            }
+            case 0xc8:
+            case 0xc9: {
+              uint8_t v = getByte(data, offset++);
+              uint8_t start =
+                  static_cast<uint8_t>(((byte == 0xc8) ? 16 : 0) + (v >> 4));
+              uint8_t count_minus_one = v & 0xf;
+              if (start + count_minus_one >= 32)
+                return _URC_FAILURE;
+              _Unwind_VRS_Pop(context, _UVRSC_VFP,
+                              RegisterRange(start, count_minus_one),
+                              _UVRSD_DOUBLE);
+              break;
+            }
+            default:
+              return _URC_FAILURE;
+          }
+          break;
+        }
+        case 0xd0: {
+          if (byte & 0x08)
+            return _URC_FAILURE;
+          _Unwind_VRS_Pop(context, _UVRSC_VFP, RegisterRange(8, byte & 0x7),
+                          _UVRSD_DOUBLE);
+          break;
+        }
+        default:
+          return _URC_FAILURE;
+      }
+    }
+  }
+  if (!wrotePC) {
+    uint32_t lr;
+    _Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_LR, _UVRSD_UINT32, &lr);
+    _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_IP, _UVRSD_UINT32, &lr);
+  }
+  return _URC_CONTINUE_UNWIND;
+}
+
+extern "C" _Unwind_Reason_Code __aeabi_unwind_cpp_pr0(
+    _Unwind_State state,
+    _Unwind_Control_Block *ucbp,
+    _Unwind_Context *context) {
+  return unwindOneFrame(state, ucbp, context);
+}
+
+extern "C" _Unwind_Reason_Code __aeabi_unwind_cpp_pr1(
+    _Unwind_State state,
+    _Unwind_Control_Block *ucbp,
+    _Unwind_Context *context) {
+  return unwindOneFrame(state, ucbp, context);
+}
+
+extern "C" _Unwind_Reason_Code __aeabi_unwind_cpp_pr2(
+    _Unwind_State state,
+    _Unwind_Control_Block *ucbp,
+    _Unwind_Context *context) {
+  return unwindOneFrame(state, ucbp, context);
+}
+
+static _Unwind_Reason_Code
+unwind_phase1(unw_context_t *uc, _Unwind_Exception *exception_object) {
+  // EHABI #7.3 discusses preserving the VRS in a "temporary VRS" during
+  // phase 1 and then restoring it to the "primary VRS" for phase 2. The
+  // effect is phase 2 doesn't see any of the VRS manipulations from phase 1.
+  // In this implementation, the phases don't share the VRS backing store.
+  // Instead, they are passed the original |uc| and they create a new VRS
+  // from scratch thus achieving the same effect.
+  unw_cursor_t cursor1;
+  unw_init_local(&cursor1, uc);
+
+  // Walk each frame looking for a place to stop.
+  for (bool handlerNotFound = true; handlerNotFound;) {
+
+#if !_LIBUNWIND_ARM_EHABI
+    // Ask libuwind to get next frame (skip over first which is
+    // _Unwind_RaiseException).
+    int stepResult = unw_step(&cursor1);
+    if (stepResult == 0) {
+      _LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): unw_step() reached "
+                                 "bottom => _URC_END_OF_STACK\n",
+                                 static_cast<void *>(exception_object));
+      return _URC_END_OF_STACK;
+    } else if (stepResult < 0) {
+      _LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): unw_step failed => "
+                                 "_URC_FATAL_PHASE1_ERROR\n",
+                                 static_cast<void *>(exception_object));
+      return _URC_FATAL_PHASE1_ERROR;
+    }
+#endif
+
+    // See if frame has code to run (has personality routine).
+    unw_proc_info_t frameInfo;
+    if (unw_get_proc_info(&cursor1, &frameInfo) != UNW_ESUCCESS) {
+      _LIBUNWIND_TRACE_UNWINDING("unwind_phase1(ex_ojb=%p): unw_get_proc_info "
+                                 "failed => _URC_FATAL_PHASE1_ERROR\n",
+                                 static_cast<void *>(exception_object));
+      return _URC_FATAL_PHASE1_ERROR;
+    }
+
+    // When tracing, print state information.
+    if (_LIBUNWIND_TRACING_UNWINDING) {
+      char functionBuf[512];
+      const char *functionName = functionBuf;
+      unw_word_t offset;
+      if ((unw_get_proc_name(&cursor1, functionBuf, sizeof(functionBuf),
+                             &offset) != UNW_ESUCCESS) ||
+          (frameInfo.start_ip + offset > frameInfo.end_ip))
+        functionName = ".anonymous.";
+      unw_word_t pc;
+      unw_get_reg(&cursor1, UNW_REG_IP, &pc);
+      _LIBUNWIND_TRACE_UNWINDING(
+          "unwind_phase1(ex_ojb=%p): pc=0x%llX, start_ip=0x%llX, func=%s, "
+          "lsda=0x%llX, personality=0x%llX\n",
+          static_cast<void *>(exception_object), (long long)pc,
+          (long long)frameInfo.start_ip, functionName,
+          (long long)frameInfo.lsda, (long long)frameInfo.handler);
+    }
+
+    // If there is a personality routine, ask it if it will want to stop at
+    // this frame.
+    if (frameInfo.handler != 0) {
+      __personality_routine p =
+          (__personality_routine)(long)(frameInfo.handler);
+      _LIBUNWIND_TRACE_UNWINDING(
+          "unwind_phase1(ex_ojb=%p): calling personality function %p\n",
+          static_cast<void *>(exception_object),
+          reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(p)));
+      struct _Unwind_Context *context = (struct _Unwind_Context *)(&cursor1);
+      exception_object->pr_cache.fnstart = frameInfo.start_ip;
+      exception_object->pr_cache.ehtp =
+          (_Unwind_EHT_Header *)frameInfo.unwind_info;
+      exception_object->pr_cache.additional = frameInfo.flags;
+      _Unwind_Reason_Code personalityResult =
+          (*p)(_US_VIRTUAL_UNWIND_FRAME, exception_object, context);
+      _LIBUNWIND_TRACE_UNWINDING(
+          "unwind_phase1(ex_ojb=%p): personality result %d start_ip %x ehtp %p "
+          "additional %x\n",
+          static_cast<void *>(exception_object), personalityResult,
+          exception_object->pr_cache.fnstart,
+          static_cast<void *>(exception_object->pr_cache.ehtp),
+          exception_object->pr_cache.additional);
+      switch (personalityResult) {
+      case _URC_HANDLER_FOUND:
+        // found a catch clause or locals that need destructing in this frame
+        // stop search and remember stack pointer at the frame
+        handlerNotFound = false;
+        // p should have initialized barrier_cache. EHABI #7.3.5
+        _LIBUNWIND_TRACE_UNWINDING(
+            "unwind_phase1(ex_ojb=%p): _URC_HANDLER_FOUND \n",
+            static_cast<void *>(exception_object));
+        return _URC_NO_REASON;
+
+      case _URC_CONTINUE_UNWIND:
+        _LIBUNWIND_TRACE_UNWINDING(
+            "unwind_phase1(ex_ojb=%p): _URC_CONTINUE_UNWIND\n",
+            static_cast<void *>(exception_object));
+        // continue unwinding
+        break;
+
+      // EHABI #7.3.3
+      case _URC_FAILURE:
+        return _URC_FAILURE;
+
+      default:
+        // something went wrong
+        _LIBUNWIND_TRACE_UNWINDING(
+            "unwind_phase1(ex_ojb=%p): _URC_FATAL_PHASE1_ERROR\n",
+            static_cast<void *>(exception_object));
+        return _URC_FATAL_PHASE1_ERROR;
+      }
+    }
+  }
+  return _URC_NO_REASON;
+}
+
+static _Unwind_Reason_Code unwind_phase2(unw_context_t *uc,
+                                         _Unwind_Exception *exception_object,
+                                         bool resume) {
+  // See comment at the start of unwind_phase1 regarding VRS integrity.
+  unw_cursor_t cursor2;
+  unw_init_local(&cursor2, uc);
+
+  _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p)\n",
+                             static_cast<void *>(exception_object));
+  int frame_count = 0;
+
+  // Walk each frame until we reach where search phase said to stop.
+  while (true) {
+    // Ask libuwind to get next frame (skip over first which is
+    // _Unwind_RaiseException or _Unwind_Resume).
+    //
+    // Resume only ever makes sense for 1 frame.
+    _Unwind_State state =
+        resume ? _US_UNWIND_FRAME_RESUME : _US_UNWIND_FRAME_STARTING;
+    if (resume && frame_count == 1) {
+      // On a resume, first unwind the _Unwind_Resume() frame. The next frame
+      // is now the landing pad for the cleanup from a previous execution of
+      // phase2. To continue unwindingly correctly, replace VRS[15] with the
+      // IP of the frame that the previous run of phase2 installed the context
+      // for. After this, continue unwinding as if normal.
+      //
+      // See #7.4.6 for details.
+      unw_set_reg(&cursor2, UNW_REG_IP,
+                  exception_object->unwinder_cache.reserved2);
+      resume = false;
+    }
+
+#if !_LIBUNWIND_ARM_EHABI
+    int stepResult = unw_step(&cursor2);
+    if (stepResult == 0) {
+      _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): unw_step() reached "
+                                 "bottom => _URC_END_OF_STACK\n",
+                                 static_cast<void *>(exception_object));
+      return _URC_END_OF_STACK;
+    } else if (stepResult < 0) {
+      _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): unw_step failed => "
+                                 "_URC_FATAL_PHASE1_ERROR\n",
+                                 static_cast<void *>(exception_object));
+      return _URC_FATAL_PHASE2_ERROR;
+    }
+#endif
+
+    // Get info about this frame.
+    unw_word_t sp;
+    unw_proc_info_t frameInfo;
+    unw_get_reg(&cursor2, UNW_REG_SP, &sp);
+    if (unw_get_proc_info(&cursor2, &frameInfo) != UNW_ESUCCESS) {
+      _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): unw_get_proc_info "
+                                 "failed => _URC_FATAL_PHASE1_ERROR\n",
+                                 static_cast<void *>(exception_object));
+      return _URC_FATAL_PHASE2_ERROR;
+    }
+
+    // When tracing, print state information.
+    if (_LIBUNWIND_TRACING_UNWINDING) {
+      char functionBuf[512];
+      const char *functionName = functionBuf;
+      unw_word_t offset;
+      if ((unw_get_proc_name(&cursor2, functionBuf, sizeof(functionBuf),
+                             &offset) != UNW_ESUCCESS) ||
+          (frameInfo.start_ip + offset > frameInfo.end_ip))
+        functionName = ".anonymous.";
+      _LIBUNWIND_TRACE_UNWINDING(
+          "unwind_phase2(ex_ojb=%p): start_ip=0x%llX, func=%s, sp=0x%llX, "
+          "lsda=0x%llX, personality=0x%llX\n",
+          static_cast<void *>(exception_object), (long long)frameInfo.start_ip,
+          functionName, (long long)sp, (long long)frameInfo.lsda,
+          (long long)frameInfo.handler);
+    }
+
+    // If there is a personality routine, tell it we are unwinding.
+    if (frameInfo.handler != 0) {
+      __personality_routine p =
+          (__personality_routine)(long)(frameInfo.handler);
+      struct _Unwind_Context *context = (struct _Unwind_Context *)(&cursor2);
+      // EHABI #7.2
+      exception_object->pr_cache.fnstart = frameInfo.start_ip;
+      exception_object->pr_cache.ehtp =
+          (_Unwind_EHT_Header *)frameInfo.unwind_info;
+      exception_object->pr_cache.additional = frameInfo.flags;
+      _Unwind_Reason_Code personalityResult =
+          (*p)(state, exception_object, context);
+      switch (personalityResult) {
+      case _URC_CONTINUE_UNWIND:
+        // Continue unwinding
+        _LIBUNWIND_TRACE_UNWINDING(
+            "unwind_phase2(ex_ojb=%p): _URC_CONTINUE_UNWIND\n",
+            static_cast<void *>(exception_object));
+        // EHABI #7.2
+        if (sp == exception_object->barrier_cache.sp) {
+          // Phase 1 said we would stop at this frame, but we did not...
+          _LIBUNWIND_ABORT("during phase1 personality function said it would "
+                           "stop here, but now in phase2 it did not stop here");
+        }
+        break;
+      case _URC_INSTALL_CONTEXT:
+        _LIBUNWIND_TRACE_UNWINDING(
+            "unwind_phase2(ex_ojb=%p): _URC_INSTALL_CONTEXT\n",
+            static_cast<void *>(exception_object));
+        // Personality routine says to transfer control to landing pad.
+        // We may get control back if landing pad calls _Unwind_Resume().
+        if (_LIBUNWIND_TRACING_UNWINDING) {
+          unw_word_t pc;
+          unw_get_reg(&cursor2, UNW_REG_IP, &pc);
+          unw_get_reg(&cursor2, UNW_REG_SP, &sp);
+          _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): re-entering "
+                                     "user code with ip=0x%llX, sp=0x%llX\n",
+                                     static_cast<void *>(exception_object),
+                                     (long long)pc, (long long)sp);
+        }
+
+        {
+          // EHABI #7.4.1 says we need to preserve pc for when _Unwind_Resume
+          // is called back, to find this same frame.
+          unw_word_t pc;
+          unw_get_reg(&cursor2, UNW_REG_IP, &pc);
+          exception_object->unwinder_cache.reserved2 = (uint32_t)pc;
+        }
+        unw_resume(&cursor2);
+        // unw_resume() only returns if there was an error.
+        return _URC_FATAL_PHASE2_ERROR;
+
+      // # EHABI #7.4.3
+      case _URC_FAILURE:
+        abort();
+
+      default:
+        // Personality routine returned an unknown result code.
+        _LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d",
+                      personalityResult);
+        return _URC_FATAL_PHASE2_ERROR;
+      }
+    }
+    frame_count++;
+  }
+
+  // Clean up phase did not resume at the frame that the search phase
+  // said it would...
+  return _URC_FATAL_PHASE2_ERROR;
+}
+
+/// Called by __cxa_throw.  Only returns if there is a fatal error.
+_LIBUNWIND_EXPORT _Unwind_Reason_Code
+_Unwind_RaiseException(_Unwind_Exception *exception_object) {
+  _LIBUNWIND_TRACE_API("_Unwind_RaiseException(ex_obj=%p)\n",
+                       static_cast<void *>(exception_object));
+  unw_context_t uc;
+  unw_getcontext(&uc);
+
+  // This field for is for compatibility with GCC to say this isn't a forced
+  // unwind. EHABI #7.2
+  exception_object->unwinder_cache.reserved1 = 0;
+
+  // phase 1: the search phase
+  _Unwind_Reason_Code phase1 = unwind_phase1(&uc, exception_object);
+  if (phase1 != _URC_NO_REASON)
+    return phase1;
+
+  // phase 2: the clean up phase
+  return unwind_phase2(&uc, exception_object, false);
+}
+
+_LIBUNWIND_EXPORT void _Unwind_Complete(_Unwind_Exception* exception_object) {
+  // This is to be called when exception handling completes to give us a chance
+  // to perform any housekeeping. EHABI #7.2. But we have nothing to do here.
+  (void)exception_object;
+}
+
+/// When _Unwind_RaiseException() is in phase2, it hands control
+/// to the personality function at each frame.  The personality
+/// may force a jump to a landing pad in that function, the landing
+/// pad code may then call _Unwind_Resume() to continue with the
+/// unwinding.  Note: the call to _Unwind_Resume() is from compiler
+/// geneated user code.  All other _Unwind_* routines are called
+/// by the C++ runtime __cxa_* routines.
+///
+/// Note: re-throwing an exception (as opposed to continuing the unwind)
+/// is implemented by having the code call __cxa_rethrow() which
+/// in turn calls _Unwind_Resume_or_Rethrow().
+_LIBUNWIND_EXPORT void
+_Unwind_Resume(_Unwind_Exception *exception_object) {
+  _LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)\n",
+                       static_cast<void *>(exception_object));
+  unw_context_t uc;
+  unw_getcontext(&uc);
+
+  // _Unwind_RaiseException on EHABI will always set the reserved1 field to 0,
+  // which is in the same position as private_1 below.
+  // TODO(ajwong): Who wronte the above? Why is it true?
+  unwind_phase2(&uc, exception_object, true);
+
+  // Clients assume _Unwind_Resume() does not return, so all we can do is abort.
+  _LIBUNWIND_ABORT("_Unwind_Resume() can't return");
+}
+
+/// Called by personality handler during phase 2 to get LSDA for current frame.
+_LIBUNWIND_EXPORT uintptr_t
+_Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) {
+  unw_cursor_t *cursor = (unw_cursor_t *)context;
+  unw_proc_info_t frameInfo;
+  uintptr_t result = 0;
+  if (unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS)
+    result = (uintptr_t)frameInfo.lsda;
+  _LIBUNWIND_TRACE_API(
+      "_Unwind_GetLanguageSpecificData(context=%p) => 0x%llx\n",
+      static_cast<void *>(context), (long long)result);
+  return result;
+}
+
+static uint64_t ValueAsBitPattern(_Unwind_VRS_DataRepresentation representation,
+                                  void* valuep) {
+  uint64_t value = 0;
+  switch (representation) {
+    case _UVRSD_UINT32:
+    case _UVRSD_FLOAT:
+      memcpy(&value, valuep, sizeof(uint32_t));
+      break;
+
+    case _UVRSD_VFPX:
+    case _UVRSD_UINT64:
+    case _UVRSD_DOUBLE:
+      memcpy(&value, valuep, sizeof(uint64_t));
+      break;
+  }
+  return value;
+}
+
+_Unwind_VRS_Result
+_Unwind_VRS_Set(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
+                uint32_t regno, _Unwind_VRS_DataRepresentation representation,
+                void *valuep) {
+  _LIBUNWIND_TRACE_API("_Unwind_VRS_Set(context=%p, regclass=%d, reg=%d, "
+                       "rep=%d, value=0x%llX)\n",
+                       static_cast<void *>(context), regclass, regno,
+                       representation,
+                       ValueAsBitPattern(representation, valuep));
+  unw_cursor_t *cursor = (unw_cursor_t *)context;
+  switch (regclass) {
+    case _UVRSC_CORE:
+      if (representation != _UVRSD_UINT32 || regno > 15)
+        return _UVRSR_FAILED;
+      return unw_set_reg(cursor, (unw_regnum_t)(UNW_ARM_R0 + regno),
+                         *(unw_word_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+    case _UVRSC_WMMXC:
+      if (representation != _UVRSD_UINT32 || regno > 3)
+        return _UVRSR_FAILED;
+      return unw_set_reg(cursor, (unw_regnum_t)(UNW_ARM_WC0 + regno),
+                         *(unw_word_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+    case _UVRSC_VFP:
+      if (representation != _UVRSD_VFPX && representation != _UVRSD_DOUBLE)
+        return _UVRSR_FAILED;
+      if (representation == _UVRSD_VFPX) {
+        // Can only touch d0-15 with FSTMFDX.
+        if (regno > 15)
+          return _UVRSR_FAILED;
+        unw_save_vfp_as_X(cursor);
+      } else {
+        if (regno > 31)
+          return _UVRSR_FAILED;
+      }
+      return unw_set_fpreg(cursor, (unw_regnum_t)(UNW_ARM_D0 + regno),
+                           *(unw_fpreg_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+    case _UVRSC_WMMXD:
+      if (representation != _UVRSD_DOUBLE || regno > 31)
+        return _UVRSR_FAILED;
+      return unw_set_fpreg(cursor, (unw_regnum_t)(UNW_ARM_WR0 + regno),
+                           *(unw_fpreg_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+  }
+  _LIBUNWIND_ABORT("unsupported register class");
+}
+
+static _Unwind_VRS_Result
+_Unwind_VRS_Get_Internal(_Unwind_Context *context,
+                         _Unwind_VRS_RegClass regclass, uint32_t regno,
+                         _Unwind_VRS_DataRepresentation representation,
+                         void *valuep) {
+  unw_cursor_t *cursor = (unw_cursor_t *)context;
+  switch (regclass) {
+    case _UVRSC_CORE:
+      if (representation != _UVRSD_UINT32 || regno > 15)
+        return _UVRSR_FAILED;
+      return unw_get_reg(cursor, (unw_regnum_t)(UNW_ARM_R0 + regno),
+                         (unw_word_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+    case _UVRSC_WMMXC:
+      if (representation != _UVRSD_UINT32 || regno > 3)
+        return _UVRSR_FAILED;
+      return unw_get_reg(cursor, (unw_regnum_t)(UNW_ARM_WC0 + regno),
+                         (unw_word_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+    case _UVRSC_VFP:
+      if (representation != _UVRSD_VFPX && representation != _UVRSD_DOUBLE)
+        return _UVRSR_FAILED;
+      if (representation == _UVRSD_VFPX) {
+        // Can only touch d0-15 with FSTMFDX.
+        if (regno > 15)
+          return _UVRSR_FAILED;
+        unw_save_vfp_as_X(cursor);
+      } else {
+        if (regno > 31)
+          return _UVRSR_FAILED;
+      }
+      return unw_get_fpreg(cursor, (unw_regnum_t)(UNW_ARM_D0 + regno),
+                           (unw_fpreg_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+    case _UVRSC_WMMXD:
+      if (representation != _UVRSD_DOUBLE || regno > 31)
+        return _UVRSR_FAILED;
+      return unw_get_fpreg(cursor, (unw_regnum_t)(UNW_ARM_WR0 + regno),
+                           (unw_fpreg_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+  }
+  _LIBUNWIND_ABORT("unsupported register class");
+}
+
+_Unwind_VRS_Result _Unwind_VRS_Get(
+    _Unwind_Context *context,
+    _Unwind_VRS_RegClass regclass,
+    uint32_t regno,
+    _Unwind_VRS_DataRepresentation representation,
+    void *valuep) {
+  _Unwind_VRS_Result result =
+      _Unwind_VRS_Get_Internal(context, regclass, regno, representation,
+                               valuep);
+  _LIBUNWIND_TRACE_API("_Unwind_VRS_Get(context=%p, regclass=%d, reg=%d, "
+                       "rep=%d, value=0x%llX, result = %d)\n",
+                       static_cast<void *>(context), regclass, regno,
+                       representation,
+                       ValueAsBitPattern(representation, valuep), result);
+  return result;
+}
+
+_Unwind_VRS_Result
+_Unwind_VRS_Pop(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
+                uint32_t discriminator,
+                _Unwind_VRS_DataRepresentation representation) {
+  _LIBUNWIND_TRACE_API("_Unwind_VRS_Pop(context=%p, regclass=%d, "
+                       "discriminator=%d, representation=%d)\n",
+                       static_cast<void *>(context), regclass, discriminator,
+                       representation);
+  switch (regclass) {
+    case _UVRSC_CORE:
+    case _UVRSC_WMMXC: {
+      if (representation != _UVRSD_UINT32)
+        return _UVRSR_FAILED;
+      // When popping SP from the stack, we don't want to override it from the
+      // computed new stack location. See EHABI #7.5.4 table 3.
+      bool poppedSP = false;
+      uint32_t* sp;
+      if (_Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_SP,
+                          _UVRSD_UINT32, &sp) != _UVRSR_OK) {
+        return _UVRSR_FAILED;
+      }
+      for (uint32_t i = 0; i < 16; ++i) {
+        if (!(discriminator & static_cast<uint32_t>(1 << i)))
+          continue;
+        uint32_t value = *sp++;
+        if (regclass == _UVRSC_CORE && i == 13)
+          poppedSP = true;
+        if (_Unwind_VRS_Set(context, regclass, i,
+                            _UVRSD_UINT32, &value) != _UVRSR_OK) {
+          return _UVRSR_FAILED;
+        }
+      }
+      if (!poppedSP) {
+        return _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP,
+                               _UVRSD_UINT32, &sp);
+      }
+      return _UVRSR_OK;
+    }
+    case _UVRSC_VFP:
+    case _UVRSC_WMMXD: {
+      if (representation != _UVRSD_VFPX && representation != _UVRSD_DOUBLE)
+        return _UVRSR_FAILED;
+      uint32_t first = discriminator >> 16;
+      uint32_t count = discriminator & 0xffff;
+      uint32_t end = first+count;
+      uint32_t* sp;
+      if (_Unwind_VRS_Get(context, _UVRSC_CORE, UNW_ARM_SP,
+                          _UVRSD_UINT32, &sp) != _UVRSR_OK) {
+        return _UVRSR_FAILED;
+      }
+      // For _UVRSD_VFPX, we're assuming the data is stored in FSTMX "standard
+      // format 1", which is equivalent to FSTMD + a padding word.
+      for (uint32_t i = first; i < end; ++i) {
+        // SP is only 32-bit aligned so don't copy 64-bit at a time.
+        uint64_t value = *sp++;
+        value |= ((uint64_t)(*sp++)) << 32;
+        if (_Unwind_VRS_Set(context, regclass, i, representation, &value) !=
+            _UVRSR_OK)
+          return _UVRSR_FAILED;
+      }
+      if (representation == _UVRSD_VFPX)
+        ++sp;
+      return _Unwind_VRS_Set(context, _UVRSC_CORE, UNW_ARM_SP, _UVRSD_UINT32,
+                             &sp);
+    }
+  }
+  _LIBUNWIND_ABORT("unsupported register class");
+}
+
+/// Called by personality handler during phase 2 to find the start of the
+/// function.
+_LIBUNWIND_EXPORT uintptr_t
+_Unwind_GetRegionStart(struct _Unwind_Context *context) {
+  unw_cursor_t *cursor = (unw_cursor_t *)context;
+  unw_proc_info_t frameInfo;
+  uintptr_t result = 0;
+  if (unw_get_proc_info(cursor, &frameInfo) == UNW_ESUCCESS)
+    result = (uintptr_t)frameInfo.start_ip;
+  _LIBUNWIND_TRACE_API("_Unwind_GetRegionStart(context=%p) => 0x%llX\n",
+                       static_cast<void *>(context), (long long)result);
+  return result;
+}
+
+
+/// Called by personality handler during phase 2 if a foreign exception
+// is caught.
+_LIBUNWIND_EXPORT void
+_Unwind_DeleteException(_Unwind_Exception *exception_object) {
+  _LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)\n",
+                       static_cast<void *>(exception_object));
+  if (exception_object->exception_cleanup != NULL)
+    (*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT,
+                                           exception_object);
+}
+
+extern "C" _LIBUNWIND_EXPORT _Unwind_Reason_Code
+__gnu_unwind_frame(_Unwind_Exception *exception_object,
+                   struct _Unwind_Context *context) {
+  unw_cursor_t *cursor = (unw_cursor_t *)context;
+  if (unw_step(cursor) != UNW_STEP_SUCCESS)
+    return _URC_FAILURE;
+  return _URC_OK;
+}
+
+#endif  // _LIBUNWIND_ARM_EHABI