Land support for ARM EHABI unwinding for libunwind.

This was written by:
Albert Wong <ajwong@chromium.org>
Antoine Labour <piman@chromium.org>
Dana Jansen <danakj@chromium.org
Jonathan Roelofs <jonathan@codesourcery.com>
Nico Weber <thakis@chromium.org>

llvm-svn: 211743

10 files changed, 1636 insertions, 83 deletions

diff --git a/libcxxabi/include/libunwind.h b/libcxxabi/include/libunwind.h
index 7b00f4fec56..7057070b306 100644
--- a/libcxxabi/include/libunwind.h
+++ b/libcxxabi/include/libunwind.h
@@ -100,6 +100,12 @@ extern int unw_set_reg(unw_cursor_t *, unw_regnum_t, unw_word_t) LIBUNWIND_AVAIL
 extern int unw_set_fpreg(unw_cursor_t *, unw_regnum_t, unw_fpreg_t)  LIBUNWIND_AVAIL;
 extern int unw_resume(unw_cursor_t *) LIBUNWIND_AVAIL;
 
+#if __arm__
+/* Save VFP registers in FSTMX format (instead of FSTMD). */
+extern void unw_save_vfp_as_X(unw_cursor_t *) LIBUNWIND_AVAIL;
+#endif
+
+
 extern const char *unw_regname(unw_cursor_t *, unw_regnum_t) LIBUNWIND_AVAIL;
 extern int unw_get_proc_info(unw_cursor_t *, unw_proc_info_t *) LIBUNWIND_AVAIL;
 extern int unw_is_fpreg(unw_cursor_t *, unw_regnum_t) LIBUNWIND_AVAIL;
diff --git a/libcxxabi/include/unwind.h b/libcxxabi/include/unwind.h
index f3a09ecd245..4e77c3a4181 100644
--- a/libcxxabi/include/unwind.h
+++ b/libcxxabi/include/unwind.h
@@ -55,6 +55,7 @@ typedef enum {
   _UA_END_OF_STACK = 16 // gcc extension to C++ ABI
 } _Unwind_Action;
 
+typedef struct _Unwind_Context _Unwind_Context;   // opaque
 
 #if LIBCXXABI_ARM_EHABI
 typedef uint32_t _Unwind_State;
@@ -73,26 +74,30 @@ struct _Unwind_Control_Block {
   uint64_t exception_class;
   void (*exception_cleanup)(_Unwind_Reason_Code, _Unwind_Control_Block*);
 
+  /* Unwinder cache, private fields for the unwinder's use */
   struct {
-    uint32_t reserved1;
+    uint32_t reserved1; /* init reserved1 to 0, then don't touch */
     uint32_t reserved2;
     uint32_t reserved3;
     uint32_t reserved4;
     uint32_t reserved5;
   } unwinder_cache;
 
+  /* Propagation barrier cache (valid after phase 1): */
   struct {
     uint32_t sp;
     uint32_t bitpattern[5];
   } barrier_cache;
 
+  /* Cleanup cache (preserved over cleanup): */
   struct {
     uint32_t bitpattern[4];
   } cleanup_cache;
 
+  /* Pr cache (for pr's benefit): */
   struct {
-    uint32_t fnstart;
-    _Unwind_EHT_Header* ehtp;
+    uint32_t fnstart; /* function start address */
+    _Unwind_EHT_Header* ehtp; /* pointer to EHT entry header word */
     uint32_t additional;
     uint32_t reserved1;
   } pr_cache;
@@ -165,10 +170,10 @@ extern void _Unwind_DeleteException(_Unwind_Exception *exception_object);
 
 #if LIBCXXABI_ARM_EHABI
 typedef enum {
-  _UVRSC_CORE = 0,
-  _UVRSC_VFP = 1,
-  _UVRSC_WMMXD = 3,
-  _UVRSC_WMMXC = 4
+  _UVRSC_CORE = 0, /* integer register */
+  _UVRSC_VFP = 1, /* vfp */
+  _UVRSC_WMMXD = 3, /* Intel WMMX data register */
+  _UVRSC_WMMXC = 4 /* Intel WMMX control register */
 } _Unwind_VRS_RegClass;
 
 typedef enum {
@@ -185,17 +190,26 @@ typedef enum {
   _UVRSR_FAILED = 2
 } _Unwind_VRS_Result;
 
-extern _Unwind_VRS_Result _Unwind_VRS_Get(_Unwind_Context* context,
-                                          _Unwind_VRS_RegClass regclass,
-                                          uint32_t regno,
-                                          _Unwind_VRS_DataRepresentation representation,
-                                          void *valuep);
+extern void _Unwind_Complete(_Unwind_Exception* exception_object);
+
+extern _Unwind_VRS_Result
+_Unwind_VRS_Get(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
+                uint32_t regno, _Unwind_VRS_DataRepresentation representation,
+                void *valuep);
+
+extern _Unwind_VRS_Result
+_Unwind_VRS_Set(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
+                uint32_t regno, _Unwind_VRS_DataRepresentation representation,
+                void *valuep);
+
+extern _Unwind_VRS_Result
+_Unwind_VRS_Pop(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
+                uint32_t discriminator,
+                _Unwind_VRS_DataRepresentation representation);
 
-extern _Unwind_VRS_Result _Unwind_VRS_Set(_Unwind_Context* context,
-                                          _Unwind_VRS_RegClass regclass,
-                                          uint32_t regno,
-                                          _Unwind_VRS_DataRepresentation representation,
-                                          void *valuep);
+extern _Unwind_Reason_Code _Unwind_VRS_Interpret(_Unwind_Context *context,
+                                                 uint32_t *data, size_t offset,
+                                                 size_t len);
 
 static inline uintptr_t _Unwind_GetGR(struct _Unwind_Context* context,
                                       int index) {
@@ -276,9 +290,9 @@ extern uintptr_t _Unwind_GetCFA(struct _Unwind_Context *);
 
 
 // _Unwind_GetIPInfo is a gcc extension that can be called from within a
-// personality handler.  Similar to _Unwind_GetIP() but also returns in 
-// *ipBefore a non-zero value if the instruction pointer is at or before the 
-// instruction causing the unwind. Normally, in a function call, the IP returned 
+// personality handler.  Similar to _Unwind_GetIP() but also returns in
+// *ipBefore a non-zero value if the instruction pointer is at or before the
+// instruction causing the unwind. Normally, in a function call, the IP returned
 // is the return address which is after the call instruction and may be past the
 // end of the function containing the call instruction.
 extern uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,
diff --git a/libcxxabi/src/Unwind/Registers.hpp b/libcxxabi/src/Unwind/Registers.hpp
index e2cfa17d2d4..8c1acfced02 100644
--- a/libcxxabi/src/Unwind/Registers.hpp
+++ b/libcxxabi/src/Unwind/Registers.hpp
@@ -1283,39 +1283,51 @@ inline void Registers_arm64::setVectorRegister(int, v128) {
 ///
 /// NOTE: Assumes VFPv3. On ARM processors without a floating point unit,
 /// this uses more memory than required.
-///
-/// FIXME: Support MMX Data Registers, Control registers, and load/stores
-/// for different representations in the VFP registers as listed in
-/// Table 1 of EHABI #7.5.2
 class _LIBUNWIND_HIDDEN Registers_arm {
 public:
   Registers_arm();
   Registers_arm(const void *registers);
 
   bool        validRegister(int num) const;
-  uint32_t    getRegister(int num) const;
+  uint32_t    getRegister(int num);
   void        setRegister(int num, uint32_t value);
-  // FIXME: Due to ARM VRS's support for reading/writing different
-  // representations into the VFP registers this set of accessors seem wrong.
-  // If {get,set}FloatRegister() is the backing store for
-  // _Unwind_VRS_{Get,Set} then it might be best to return a tagged union
-  // with types for each representation in _Unwind_VRS_DataRepresentation.
-  // Similarly, unw_{get,set}_fpreg in the public libunwind API may want to
-  // use a similar tagged union to back the unw_fpreg_t output parameter type.
   bool        validFloatRegister(int num) const;
-  unw_fpreg_t getFloatRegister(int num) const;
+  unw_fpreg_t getFloatRegister(int num);
   void        setFloatRegister(int num, unw_fpreg_t value);
   bool        validVectorRegister(int num) const;
   v128        getVectorRegister(int num) const;
   void        setVectorRegister(int num, v128 value);
   const char *getRegisterName(int num);
-  void        jumpto();
+  void        jumpto() {
+    restoreSavedFloatRegisters();
+    restoreCoreAndJumpTo();
+  }
 
   uint32_t  getSP() const         { return _registers.__sp; }
   void      setSP(uint32_t value) { _registers.__sp = value; }
   uint32_t  getIP() const         { return _registers.__pc; }
   void      setIP(uint32_t value) { _registers.__pc = value; }
 
+  void saveVFPAsX() {
+    assert(_use_X_for_vfp_save || !_saved_vfp_d0_d15);
+    _use_X_for_vfp_save = true;
+  }
+
+  void restoreSavedFloatRegisters() {
+    if (_saved_vfp_d0_d15) {
+      if (_use_X_for_vfp_save)
+        restoreVFPWithFLDMX(_vfp_d0_d15_pad);
+      else
+        restoreVFPWithFLDMD(_vfp_d0_d15_pad);
+    }
+    if (_saved_vfp_d16_d31)
+      restoreVFPv3(_vfp_d16_d31);
+    if (_saved_iwmmx)
+      restoreiWMMX(_iwmmx);
+    if (_saved_iwmmx_control)
+      restoreiWMMXControl(_iwmmx_control);
+  }
+
 private:
   struct GPRs {
     uint32_t __r[13]; // r0-r12
@@ -1324,17 +1336,74 @@ private:
     uint32_t __pc;    // Program counter r15
   };
 
-  GPRs    _registers;
+  static void saveVFPWithFSTMD(unw_fpreg_t*);
+  static void saveVFPWithFSTMX(unw_fpreg_t*);
+  static void saveVFPv3(unw_fpreg_t*);
+  static void saveiWMMX(unw_fpreg_t*);
+  static void saveiWMMXControl(uint32_t*);
+  static void restoreVFPWithFLDMD(unw_fpreg_t*);
+  static void restoreVFPWithFLDMX(unw_fpreg_t*);
+  static void restoreVFPv3(unw_fpreg_t*);
+  static void restoreiWMMX(unw_fpreg_t*);
+  static void restoreiWMMXControl(uint32_t*);
+  void restoreCoreAndJumpTo();
+
+  // ARM registers
+  GPRs _registers;
+
+  // We save floating point registers lazily because we can't know ahead of
+  // time which ones are used. See EHABI #4.7.
+
+  // Whether D0-D15 are saved in the FTSMX instead of FSTMD format.
+  //
+  // See EHABI #7.5 that explains how matching instruction sequences for load
+  // and store need to be used to correctly restore the exact register bits.
+  bool _use_X_for_vfp_save;
+  // Whether VFP D0-D15 are saved.
+  bool _saved_vfp_d0_d15;
+  // Whether VFPv3 D16-D31 are saved.
+  bool _saved_vfp_d16_d31;
+  // Whether iWMMX data registers are saved.
+  bool _saved_iwmmx;
+  // Whether iWMMX control registers are saved.
+  bool _saved_iwmmx_control;
+  // VFP registers D0-D15, + padding if saved using FSTMX
+  unw_fpreg_t _vfp_d0_d15_pad[17];
+  // VFPv3 registers D16-D31, always saved using FSTMD
+  unw_fpreg_t _vfp_d16_d31[16];
+  // iWMMX registers
+  unw_fpreg_t _iwmmx[16];
+  // iWMMX control registers
+  uint32_t _iwmmx_control[4];
 };
 
-inline Registers_arm::Registers_arm(const void *registers) {
+inline Registers_arm::Registers_arm(const void *registers)
+  : _use_X_for_vfp_save(false),
+    _saved_vfp_d0_d15(false),
+    _saved_vfp_d16_d31(false),
+    _saved_iwmmx(false),
+    _saved_iwmmx_control(false) {
   static_assert(sizeof(Registers_arm) < sizeof(unw_context_t),
                     "arm registers do not fit into unw_context_t");
+  // See unw_getcontext() note about data.
   memcpy(&_registers, registers, sizeof(_registers));
+  memset(&_vfp_d0_d15_pad, 0, sizeof(_vfp_d0_d15_pad));
+  memset(&_vfp_d16_d31, 0, sizeof(_vfp_d16_d31));
+  memset(&_iwmmx, 0, sizeof(_iwmmx));
+  memset(&_iwmmx_control, 0, sizeof(_iwmmx_control));
 }
 
-inline Registers_arm::Registers_arm() {
+inline Registers_arm::Registers_arm()
+  : _use_X_for_vfp_save(false),
+    _saved_vfp_d0_d15(false),
+    _saved_vfp_d16_d31(false),
+    _saved_iwmmx(false),
+    _saved_iwmmx_control(false) {
   memset(&_registers, 0, sizeof(_registers));
+  memset(&_vfp_d0_d15_pad, 0, sizeof(_vfp_d0_d15_pad));
+  memset(&_vfp_d16_d31, 0, sizeof(_vfp_d16_d31));
+  memset(&_iwmmx, 0, sizeof(_iwmmx));
+  memset(&_iwmmx_control, 0, sizeof(_iwmmx_control));
 }
 
 inline bool Registers_arm::validRegister(int regNum) const {
@@ -1344,20 +1413,29 @@ inline bool Registers_arm::validRegister(int regNum) const {
     return true;
   if (regNum == UNW_REG_SP)
     return true;
-  if ((regNum >= UNW_ARM_R0) && (regNum <= UNW_ARM_R15))
+  if (regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R15)
+    return true;
+  if (regNum >= UNW_ARM_WC0 && regNum <= UNW_ARM_WC3)
     return true;
   return false;
 }
 
-inline uint32_t Registers_arm::getRegister(int regNum) const {
+inline uint32_t Registers_arm::getRegister(int regNum) {
   if (regNum == UNW_REG_SP || regNum == UNW_ARM_SP)
     return _registers.__sp;
   if (regNum == UNW_ARM_LR)
     return _registers.__lr;
   if (regNum == UNW_REG_IP || regNum == UNW_ARM_IP)
     return _registers.__pc;
-  if ((regNum >= UNW_ARM_R0) && (regNum <= UNW_ARM_R12))
+  if (regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R12)
     return _registers.__r[regNum];
+  if (regNum >= UNW_ARM_WC0 && regNum <= UNW_ARM_WC3) {
+    if (!_saved_iwmmx_control) {
+      _saved_iwmmx_control = true;
+      saveiWMMXControl(_iwmmx_control);
+    }
+    return _iwmmx_control[regNum - UNW_ARM_WC0];
+  }
   _LIBUNWIND_ABORT("unsupported arm register");
 }
 
@@ -1368,9 +1446,15 @@ inline void Registers_arm::setRegister(int regNum, uint32_t value) {
     _registers.__lr = value;
   else if (regNum == UNW_REG_IP || regNum == UNW_ARM_IP)
     _registers.__pc = value;
-  else if ((regNum >= UNW_ARM_R0) && (regNum <= UNW_ARM_R12))
+  else if (regNum >= UNW_ARM_R0 && regNum <= UNW_ARM_R12)
     _registers.__r[regNum] = value;
-  else
+  else if (regNum >= UNW_ARM_WC0 && regNum <= UNW_ARM_WC3) {
+    if (!_saved_iwmmx_control) {
+      _saved_iwmmx_control = true;
+      saveiWMMXControl(_iwmmx_control);
+    }
+    _iwmmx_control[regNum - UNW_ARM_WC0] = value;
+  } else
     _LIBUNWIND_ABORT("unsupported arm register");
 }
 
@@ -1543,17 +1627,65 @@ inline const char *Registers_arm::getRegisterName(int regNum) {
   }
 }
 
-inline bool Registers_arm::validFloatRegister(int) const {
-  // FIXME: Implement float register support.
-  return false;
+inline bool Registers_arm::validFloatRegister(int regNum) const {
+  // NOTE: Consider the intel MMX registers floating points so the
+  // unw_get_fpreg can be used to transmit the 64-bit data back.
+  return ((regNum >= UNW_ARM_D0) && (regNum <= UNW_ARM_D31))
+      || ((regNum >= UNW_ARM_WR0) && (regNum <= UNW_ARM_WR15));
 }
 
-inline unw_fpreg_t Registers_arm::getFloatRegister(int) const {
-  _LIBUNWIND_ABORT("ARM float register support not yet implemented");
+inline unw_fpreg_t Registers_arm::getFloatRegister(int regNum) {
+  if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D15) {
+    if (!_saved_vfp_d0_d15) {
+      _saved_vfp_d0_d15 = true;
+      if (_use_X_for_vfp_save)
+        saveVFPWithFSTMX(_vfp_d0_d15_pad);
+      else
+        saveVFPWithFSTMD(_vfp_d0_d15_pad);
+    }
+    return _vfp_d0_d15_pad[regNum - UNW_ARM_D0];
+  } else if (regNum >= UNW_ARM_D16 && regNum <= UNW_ARM_D31) {
+    if (!_saved_vfp_d16_d31) {
+      _saved_vfp_d16_d31 = true;
+      saveVFPv3(_vfp_d16_d31);
+    }
+    return _vfp_d16_d31[regNum - UNW_ARM_D16];
+  } else if (regNum >= UNW_ARM_WR0 && regNum <= UNW_ARM_WR15) {
+    if (!_saved_iwmmx) {
+      _saved_iwmmx = true;
+      saveiWMMX(_iwmmx);
+    }
+    return _iwmmx[regNum - UNW_ARM_WR0];
+  } else {
+    _LIBUNWIND_ABORT("Unknown ARM float register");
+  }
 }
 
-inline void Registers_arm::setFloatRegister(int, unw_fpreg_t) {
-  _LIBUNWIND_ABORT("ARM float register support not yet implemented");
+inline void Registers_arm::setFloatRegister(int regNum, unw_fpreg_t value) {
+  if (regNum >= UNW_ARM_D0 && regNum <= UNW_ARM_D15) {
+    if (!_saved_vfp_d0_d15) {
+      _saved_vfp_d0_d15 = true;
+      if (_use_X_for_vfp_save)
+        saveVFPWithFSTMX(_vfp_d0_d15_pad);
+      else
+        saveVFPWithFSTMD(_vfp_d0_d15_pad);
+    }
+    _vfp_d0_d15_pad[regNum - UNW_ARM_D0] = value;
+  } else if (regNum >= UNW_ARM_D16 && regNum <= UNW_ARM_D31) {
+    if (!_saved_vfp_d16_d31) {
+      _saved_vfp_d16_d31 = true;
+      saveVFPv3(_vfp_d16_d31);
+    }
+    _vfp_d16_d31[regNum - UNW_ARM_D0] = value;
+  } else if (regNum >= UNW_ARM_WR0 && regNum <= UNW_ARM_WR15) {
+    if (!_saved_iwmmx) {
+      _saved_iwmmx = true;
+      saveiWMMX(_iwmmx);
+    }
+    _iwmmx[regNum - UNW_ARM_WR0] = value;
+  } else {
+    _LIBUNWIND_ABORT("Unknown ARM float register");
+  }
 }
 
 inline bool Registers_arm::validVectorRegister(int) const {
diff --git a/libcxxabi/src/Unwind/Unwind-EHABI.cpp b/libcxxabi/src/Unwind/Unwind-EHABI.cpp
new file mode 100644
index 00000000000..f4619f08d90
--- /dev/null
+++ b/libcxxabi/src/Unwind/Unwind-EHABI.cpp
@@ -0,0 +1,952 @@
+//===--------------------------- 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.h>
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "config.h"
+#include "libunwind.h"
+#include "unwind.h"
+#include "../private_typeinfo.h"
+
+#if LIBCXXABI_ARM_EHABI
+namespace {
+
+// Strange order: take words in order, but inside word, take from most to least
+// signinficant byte.
+uint8_t getByte(uint32_t* data, size_t offset) {
+  uint8_t* byteData = reinterpret_cast<uint8_t*>(data);
+  return byteData[(offset & ~0x03) + (3 - (offset&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;
+}
+
+static inline uint32_t signExtendPrel31(uint32_t data) {
+  return data | ((data & 0x40000000u) << 1);
+}
+
+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,
+    int flags) {
+  // EHT is inlined in the index using compact form. No descriptors. #5
+  if (flags & 0x1)
+    return _URC_CONTINUE_UNWIND;
+
+  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 &= ~1;
+    offset &= ~1;
+    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.
+          bool is_reference_type = landing_pad & 0x80000000;
+          landing_pad = signExtendPrel31(landing_pad & ~0x80000000);
+          if (landing_pad == 0xffffffff) {
+            return _URC_HANDLER_FOUND;
+          } else if (landing_pad == 0xfffffffe ) {
+            return _URC_FAILURE;
+          } else {
+            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;
+}
+
+_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
+  uint32_t* unwindingData = ucbp->pr_cache.ehtp;
+  uint32_t unwindInfo = *unwindingData;
+  assert((unwindInfo & 0xf0000000) == 0x80000000 && "Must be a compact entry");
+  Descriptor::Format format =
+      static_cast<Descriptor::Format>((unwindInfo & 0x0f000000) >> 24);
+  size_t len = 0;
+  size_t startOffset = 0;
+  switch (format) {
+    case Descriptor::SU16:
+      len = 4;
+      startOffset = 1;
+      break;
+    case Descriptor::LU16:
+    case Descriptor::LU32:
+      len = 4 + 4 * ((unwindInfo & 0x00ff0000) >> 16);
+      startOffset = 2;
+      break;
+    default:
+      return _URC_FAILURE;
+  }
+
+  // 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,
+          reinterpret_cast<const char*>(ucbp->pr_cache.ehtp) + len,
+          ucbp->pr_cache.additional);
+
+  if (result != _URC_CONTINUE_UNWIND)
+    return result;
+
+  return _Unwind_VRS_Interpret(context, unwindingData, startOffset, len);
+}
+
+// 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 (start << 16) | (count_minus_one + 1);
+}
+
+} // end anonymous namespace
+
+_Unwind_Reason_Code _Unwind_VRS_Interpret(
+    _Unwind_Context* context,
+    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 -= ((byte & 0x3f) << 2) + 4;
+      else
+        sp += (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;
+          uint16_t registers =
+              ((byte & 0x0f) << 12) | (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(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 = 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 = ((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;) {
+
+    // 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",
+                            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",
+                            exception_object);
+      return _URC_FATAL_PHASE1_ERROR;
+    }
+
+    // See if frame has code to run (has personality routine).
+    unw_proc_info_t frameInfo;
+    unw_word_t sp;
+    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",
+                            exception_object);
+      return _URC_FATAL_PHASE1_ERROR;
+    }
+
+    // When tracing, print state information.
+    if (_LIBUNWIND_TRACING_UNWINDING) {
+      char functionName[512];
+      unw_word_t offset;
+      if ((unw_get_proc_name(&cursor1, functionName, 512, &offset) !=
+           UNW_ESUCCESS) || (frameInfo.start_ip + offset > frameInfo.end_ip))
+        strcpy(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",
+          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",
+          exception_object, 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",
+          exception_object, personalityResult,
+          exception_object->pr_cache.fnstart, 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",
+                                   exception_object);
+        return _URC_NO_REASON;
+
+      case _URC_CONTINUE_UNWIND:
+        _LIBUNWIND_TRACE_UNWINDING(
+            "unwind_phase1(ex_ojb=%p): _URC_CONTINUE_UNWIND\n",
+            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",
+            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", 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;
+    }
+
+    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",
+                            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",
+                            exception_object);
+      return _URC_FATAL_PHASE2_ERROR;
+    }
+
+    // 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",
+                            exception_object);
+      return _URC_FATAL_PHASE2_ERROR;
+    }
+
+    // When tracing, print state information.
+    if (_LIBUNWIND_TRACING_UNWINDING) {
+      char functionName[512];
+      unw_word_t offset;
+      if ((unw_get_proc_name(&cursor2, functionName, 512, &offset) !=
+           UNW_ESUCCESS) || (frameInfo.start_ip + offset > frameInfo.end_ip))
+        strcpy(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",
+          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",
+            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",
+            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",
+                                     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",
+                             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.
+}
+
+/// 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", 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", context, (long long)result);
+  if (result != 0) {
+    if (*((uint8_t *)result) != 0xFF)
+      _LIBUNWIND_DEBUG_LOG("lsda at 0x%llx does not start with 0xFF\n",
+                           (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", 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_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_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_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_ARM_WR0 + regno,
+                           *(unw_fpreg_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+  }
+}
+
+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_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_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_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_ARM_WR0 + regno,
+                           (unw_fpreg_t *)valuep) == UNW_ESUCCESS
+                 ? _UVRSR_OK
+                 : _UVRSR_FAILED;
+  }
+}
+
+_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",
+                       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",
+                        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 (int i = 0; i < 16; ++i) {
+        if (!(discriminator & (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);
+    }
+  };
+}
+
+/// 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",
+                             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",
+                              exception_object);
+  if (exception_object->exception_cleanup != NULL)
+    (*exception_object->exception_cleanup)(_URC_FOREIGN_EXCEPTION_CAUGHT,
+                                           exception_object);
+}
+
+#endif  // LIBCXXABI_ARM_EHABI
diff --git a/libcxxabi/src/Unwind/UnwindCursor.hpp b/libcxxabi/src/Unwind/UnwindCursor.hpp
index fd5826b941a..fa79afac387 100644
--- a/libcxxabi/src/Unwind/UnwindCursor.hpp
+++ b/libcxxabi/src/Unwind/UnwindCursor.hpp
@@ -12,10 +12,12 @@
 #ifndef __UNWINDCURSOR_HPP__
 #define __UNWINDCURSOR_HPP__
 
+#include <algorithm>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <pthread.h>
+#include <unwind.h>
 
 #if __APPLE__
   #include <mach-o/dyld.h>
@@ -370,8 +372,8 @@ public:
   virtual unw_word_t  getReg(int) = 0;
   virtual void        setReg(int, unw_word_t) = 0;
   virtual bool        validFloatReg(int) = 0;
-  virtual double      getFloatReg(int) = 0;
-  virtual void        setFloatReg(int, double) = 0;
+  virtual unw_fpreg_t getFloatReg(int) = 0;
+  virtual void        setFloatReg(int, unw_fpreg_t) = 0;
   virtual int         step() = 0;
   virtual void        getInfo(unw_proc_info_t *) = 0;
   virtual void        jumpto() = 0;
@@ -379,6 +381,9 @@ public:
   virtual bool        getFunctionName(char *bf, size_t ln, unw_word_t *off) = 0;
   virtual void        setInfoBasedOnIPRegister(bool isReturnAddr = false) = 0;
   virtual const char *getRegisterName(int num) = 0;
+#if __arm__
+  virtual void        saveVFPAsX() = 0;
+#endif
 };
 
 
@@ -395,8 +400,8 @@ public:
   virtual unw_word_t  getReg(int);
   virtual void        setReg(int, unw_word_t);
   virtual bool        validFloatReg(int);
-  virtual double      getFloatReg(int);
-  virtual void        setFloatReg(int, double);
+  virtual unw_fpreg_t getFloatReg(int);
+  virtual void        setFloatReg(int, unw_fpreg_t);
   virtual int         step();
   virtual void        getInfo(unw_proc_info_t *);
   virtual void        jumpto();
@@ -404,11 +409,18 @@ public:
   virtual bool        getFunctionName(char *buf, size_t len, unw_word_t *off);
   virtual void        setInfoBasedOnIPRegister(bool isReturnAddress = false);
   virtual const char *getRegisterName(int num);
+#if __arm__
+  virtual void        saveVFPAsX();
+#endif
 
   void            operator delete(void *, size_t) {}
 
 private:
 
+#if LIBCXXABI_ARM_EHABI
+  bool getInfoFromEHABISection(pint_t pc, const UnwindInfoSections &sects);
+#endif
+
 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
   bool getInfoFromDwarfSection(pint_t pc, const UnwindInfoSections &sects,
                                             uint32_t fdeSectionOffsetHint=0);
@@ -486,7 +498,9 @@ private:
     }
     return false;
   }
+#endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
 
+#if _LIBUNWIND_SUPPORT_DWARF_UNWIND
   compact_unwind_encoding_t dwarfEncoding() const {
     R dummy;
     return dwarfEncoding(dummy);
@@ -507,7 +521,7 @@ private:
   compact_unwind_encoding_t dwarfEncoding(Registers_arm64 &) const {
     return UNWIND_ARM64_MODE_DWARF;
   }
-#endif // _LIBUNWIND_SUPPORT_COMPACT_UNWIND
+#endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND
 
 
   A               &_addressSpace;
@@ -524,14 +538,13 @@ UnwindCursor<A, R>::UnwindCursor(unw_context_t *context, A &as)
       _isSignalFrame(false) {
   static_assert(sizeof(UnwindCursor<A, R>) < sizeof(unw_cursor_t),
                 "UnwindCursor<> does not fit in unw_cursor_t");
-
-  bzero(&_info, sizeof(_info));
+  memset(&_info, 0, sizeof(_info));
 }
 
 template <typename A, typename R>
 UnwindCursor<A, R>::UnwindCursor(A &as, void *)
     : _addressSpace(as), _unwindInfoMissing(false), _isSignalFrame(false) {
-  bzero(&_info, sizeof(_info));
+  memset(&_info, 0, sizeof(_info));
   // FIXME
   // fill in _registers from thread arg
 }
@@ -558,12 +571,12 @@ bool UnwindCursor<A, R>::validFloatReg(int regNum) {
 }
 
 template <typename A, typename R>
-double UnwindCursor<A, R>::getFloatReg(int regNum) {
+unw_fpreg_t UnwindCursor<A, R>::getFloatReg(int regNum) {
   return _registers.getFloatRegister(regNum);
 }
 
 template <typename A, typename R>
-void UnwindCursor<A, R>::setFloatReg(int regNum, double value) {
+void UnwindCursor<A, R>::setFloatReg(int regNum, unw_fpreg_t value) {
   _registers.setFloatRegister(regNum, value);
 }
 
@@ -571,6 +584,12 @@ template <typename A, typename R> void UnwindCursor<A, R>::jumpto() {
   _registers.jumpto();
 }
 
+#if __arm__
+template <typename A, typename R> void UnwindCursor<A, R>::saveVFPAsX() {
+  _registers.saveVFPAsX();
+}
+#endif
+
 template <typename A, typename R>
 const char *UnwindCursor<A, R>::getRegisterName(int regNum) {
   return _registers.getRegisterName(regNum);
@@ -580,6 +599,212 @@ template <typename A, typename R> bool UnwindCursor<A, R>::isSignalFrame() {
   return _isSignalFrame;
 }
 
+#if LIBCXXABI_ARM_EHABI
+struct EHABIIndexEntry {
+  uint32_t functionOffset;
+  uint32_t data;
+};
+
+// Unable to unwind in the ARM index table (section 5 EHABI).
+#define UNW_EXIDX_CANTUNWIND 0x1
+
+static inline uint32_t signExtendPrel31(uint32_t data) {
+  return data | ((data & 0x40000000u) << 1);
+}
+
+extern "C" _Unwind_Reason_Code __aeabi_unwind_cpp_pr0(
+    _Unwind_State state, _Unwind_Control_Block *ucbp, _Unwind_Context *context);
+extern "C" _Unwind_Reason_Code __aeabi_unwind_cpp_pr1(
+    _Unwind_State state, _Unwind_Control_Block *ucbp, _Unwind_Context *context);
+extern "C" _Unwind_Reason_Code __aeabi_unwind_cpp_pr2(
+    _Unwind_State state, _Unwind_Control_Block *ucbp, _Unwind_Context *context);
+
+template<typename A>
+struct EHABISectionIterator {
+  typedef EHABISectionIterator _Self;
+
+  typedef std::random_access_iterator_tag iterator_category;
+  typedef typename A::pint_t value_type;
+  typedef typename A::pint_t* pointer;
+  typedef typename A::pint_t& reference;
+  typedef size_t size_type;
+  typedef size_t difference_type;
+
+  static _Self begin(A& addressSpace, const UnwindInfoSections& sects) {
+    return _Self(addressSpace, sects, 0);
+  }
+  static _Self end(A& addressSpace, const UnwindInfoSections& sects) {
+    return _Self(addressSpace, sects, sects.arm_section_length);
+  }
+
+  EHABISectionIterator(A& addressSpace, const UnwindInfoSections& sects, size_t i)
+      : _addressSpace(&addressSpace), _sects(&sects), _i(i) {}
+
+  _Self& operator++() { ++_i; return *this; }
+  _Self& operator+=(size_t a) { _i += a; return *this; }
+  _Self& operator--() { assert(_i > 0); --_i; return *this; }
+  _Self& operator-=(size_t a) { assert(_i >= a); _i -= a; return *this; }
+
+  _Self operator+(size_t a) { _Self out = *this; out._i += a; return out; }
+  _Self operator-(size_t a) { assert(_i >= a); _Self out = *this; out._i -= a; return out; }
+
+  size_t operator-(const _Self& other) { return _i - other._i; }
+
+  bool operator==(const _Self& other) const {
+    assert(_addressSpace == other._addressSpace);
+    assert(_sects == other._sects);
+    return _i == other._i;
+  }
+
+  typename A::pint_t operator*() const { return functionAddress(); }
+
+  typename A::pint_t functionAddress() const {
+    typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
+        EHABIIndexEntry, _i, functionOffset);
+    return indexAddr + signExtendPrel31(_addressSpace->get32(indexAddr));
+  }
+
+  typename A::pint_t dataAddress() {
+    typename A::pint_t indexAddr = _sects->arm_section + arrayoffsetof(
+        EHABIIndexEntry, _i, data);
+    return indexAddr;
+  }
+
+ private:
+  size_t _i;
+  A* _addressSpace;
+  const UnwindInfoSections* _sects;
+};
+
+template <typename A, typename R>
+bool UnwindCursor<A, R>::getInfoFromEHABISection(
+    pint_t pc,
+    const UnwindInfoSections &sects) {
+  EHABISectionIterator<A> begin =
+      EHABISectionIterator<A>::begin(_addressSpace, sects);
+  EHABISectionIterator<A> end =
+      EHABISectionIterator<A>::end(_addressSpace, sects);
+
+  EHABISectionIterator<A> itNextPC = std::upper_bound(begin, end, pc);
+  if (itNextPC == begin || itNextPC == end)
+    return false;
+  EHABISectionIterator<A> itThisPC = itNextPC - 1;
+
+  pint_t thisPC = itThisPC.functionAddress();
+  pint_t nextPC = itNextPC.functionAddress();
+  pint_t indexDataAddr = itThisPC.dataAddress();
+
+  if (indexDataAddr == 0)
+    return false;
+
+  uint32_t indexData = _addressSpace.get32(indexDataAddr);
+  if (indexData == UNW_EXIDX_CANTUNWIND)
+    return false;
+
+  // If the high bit is set, the exception handling table entry is inline inside
+  // the index table entry on the second word (aka |indexDataAddr|). Otherwise,
+  // the table points at an offset in the exception handling table (section 5 EHABI).
+  pint_t exceptionTableAddr;
+  uint32_t exceptionTableData;
+  bool isSingleWordEHT;
+  if (indexData & 0x80000000) {
+    exceptionTableAddr = indexDataAddr;
+    // TODO(ajwong): Should this data be 0?
+    exceptionTableData = indexData;
+    isSingleWordEHT = true;
+  } else {
+    exceptionTableAddr = indexDataAddr + signExtendPrel31(indexData);
+    exceptionTableData = _addressSpace.get32(exceptionTableAddr);
+    isSingleWordEHT = false;
+  }
+
+  // Now we know the 3 things:
+  //   exceptionTableAddr -- exception handler table entry.
+  //   exceptionTableData -- the data inside the first word of the eht entry.
+  //   isSingleWordEHT -- whether the entry is in the index.
+  unw_word_t personalityRoutine = 0xbadf00d;
+  bool scope32 = false;
+  uintptr_t lsda = 0xbadf00d;
+
+  // If the high bit in the exception handling table entry is set, the entry is
+  // in compact form (section 6.3 EHABI).
+  if (exceptionTableData & 0x80000000) {
+    // Grab the index of the personality routine from the compact form.
+    int choice = (exceptionTableData & 0x0f000000) >> 24;
+    int extraWords = 0;
+    switch (choice) {
+      case 0:
+        personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr0;
+        extraWords = 0;
+        scope32 = false;
+        break;
+      case 1:
+        personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr1;
+        extraWords = (exceptionTableData & 0x00ff0000) >> 16;
+        scope32 = false;
+        break;
+      case 2:
+        personalityRoutine = (unw_word_t) &__aeabi_unwind_cpp_pr2;
+        extraWords = (exceptionTableData & 0x00ff0000) >> 16;
+        scope32 = true;
+        break;
+      default:
+        _LIBUNWIND_ABORT("unknown personality routine");
+        return false;
+    }
+
+    if (isSingleWordEHT) {
+      if (extraWords != 0) {
+        _LIBUNWIND_ABORT("index inlined table detected but pr function "
+                         "requires extra words");
+        return false;
+      }
+    }
+  } else {
+    pint_t personalityAddr =
+        exceptionTableAddr + signExtendPrel31(exceptionTableData);
+    personalityRoutine = personalityAddr;
+
+    // ARM EHABI # 6.2, # 9.2
+    //
+    //  +---- ehtp
+    //  v
+    // +--------------------------------------+
+    // | +--------+--------+--------+-------+ |
+    // | |0| prel31 to personalityRoutine   | |
+    // | +--------+--------+--------+-------+ |
+    // | |      N |      unwind opcodes     | |  <-- UnwindData
+    // | +--------+--------+--------+-------+ |
+    // | | Word 2        unwind opcodes     | |
+    // | +--------+--------+--------+-------+ |
+    // | ...                                  |
+    // | +--------+--------+--------+-------+ |
+    // | | Word N        unwind opcodes     | |
+    // | +--------+--------+--------+-------+ |
+    // | | LSDA                             | |  <-- lsda
+    // | | ...                              | |
+    // | +--------+--------+--------+-------+ |
+    // +--------------------------------------+
+
+    uint32_t *UnwindData = reinterpret_cast<uint32_t*>(exceptionTableAddr) + 1;
+    uint32_t FirstDataWord = *UnwindData;
+    size_t N = ((FirstDataWord >> 24) & 0xff);
+    size_t NDataWords = N + 1;
+    lsda = reinterpret_cast<uintptr_t>(UnwindData + NDataWords);
+  }
+
+  _info.start_ip = thisPC;
+  _info.end_ip = nextPC;
+  _info.handler = personalityRoutine;
+  _info.unwind_info = exceptionTableAddr;
+  _info.lsda = lsda;
+  // flags is pr_cache.additional. See EHABI #7.2 for definition of bit 0.
+  _info.flags = isSingleWordEHT ? 1 : 0 | scope32 ? 0x2 : 0;  // Use enum?
+
+  return true;
+}
+#endif
+
 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
 template <typename A, typename R>
 bool UnwindCursor<A, R>::getInfoFromDwarfSection(pint_t pc,
@@ -913,6 +1138,11 @@ bool UnwindCursor<A, R>::getInfoFromCompactEncodingSection(pint_t pc,
 template <typename A, typename R>
 void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
   pint_t pc = (pint_t)this->getReg(UNW_REG_IP);
+#if LIBCXXABI_ARM_EHABI
+  // Remove the thumb bit so the IP represents the actual instruction address.
+  // This matches the behaviour of _Unwind_GetIP on arm.
+  pc &= (pint_t)~0x1;
+#endif
 
   // If the last line of a function is a "throw" the compiler sometimes
   // emits no instructions after the call to __cxa_throw.  This means
@@ -957,6 +1187,12 @@ void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
       }
     }
 #endif
+
+#if LIBCXXABI_ARM_EHABI
+    // If there is ARM EHABI unwind info, look there next.
+    if (sects.arm_section != 0 && this->getInfoFromEHABISection(pc, sects))
+      return;
+#endif
   }
 
 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
@@ -1026,7 +1262,7 @@ void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
 
 template <typename A, typename R>
 int UnwindCursor<A, R>::step() {
-  // Bottom of stack is defined is when no unwind info cannot be found.
+  // Bottom of stack is defined is when unwind info cannot be found.
   if (_unwindInfoMissing)
     return UNW_STEP_END;
 
@@ -1036,8 +1272,12 @@ int UnwindCursor<A, R>::step() {
   result = this->stepWithCompactEncoding();
 #elif _LIBUNWIND_SUPPORT_DWARF_UNWIND
   result = this->stepWithDwarfFDE();
+#elif LIBCXXABI_ARM_EHABI
+  result = UNW_STEP_SUCCESS;
 #else
-  #error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or _LIBUNWIND_SUPPORT_DWARF_UNWIND
+  #error Need _LIBUNWIND_SUPPORT_COMPACT_UNWIND or \
+              _LIBUNWIND_SUPPORT_DWARF_UNWIND or \
+              LIBCXXABI_ARM_EHABI
 #endif
 
   // update info based on new PC
diff --git a/libcxxabi/src/Unwind/UnwindLevel1-gcc-ext.c b/libcxxabi/src/Unwind/UnwindLevel1-gcc-ext.c
index c84db76c53f..745c30922c4 100644
--- a/libcxxabi/src/Unwind/UnwindLevel1-gcc-ext.c
+++ b/libcxxabi/src/Unwind/UnwindLevel1-gcc-ext.c
@@ -24,10 +24,21 @@
 
 ///  Called by __cxa_rethrow().
 _LIBUNWIND_EXPORT _Unwind_Reason_Code
-_Unwind_Resume_or_Rethrow(struct _Unwind_Exception *exception_object) {
+_Unwind_Resume_or_Rethrow(_Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_API("_Unwind_Resume_or_Rethrow(ex_obj=%p), "
-                             "private_1=%ld\n",
-                              exception_object, exception_object->private_1);
+                       "private_1=%ld\n",
+                       exception_object,
+#if LIBCXXABI_ARM_EHABI
+                       (long)exception_object->unwinder_cache.reserved1);
+#else
+                       (long)exception_object->private_1);
+#endif
+
+#if LIBCXXABI_ARM_EHABI
+  // _Unwind_RaiseException on EHABI will always set the reserved1 field to 0,
+  // which is in the same position as private_1 below.
+  return _Unwind_RaiseException(exception_object);
+#else
   // If this is non-forced and a stopping place was found, then this is a
   // re-throw.
   // Call _Unwind_RaiseException() as if this was a new exception
@@ -42,6 +53,7 @@ _Unwind_Resume_or_Rethrow(struct _Unwind_Exception *exception_object) {
   _Unwind_Resume(exception_object);
   _LIBUNWIND_ABORT("_Unwind_Resume_or_Rethrow() called _Unwind_RaiseException()"
                    " which unexpectedly returned");
+#endif
 }
 
 
@@ -116,7 +128,8 @@ _Unwind_Backtrace(_Unwind_Trace_Fn callback, void *ref) {
       unw_get_proc_info(&cursor, &frameInfo);
       _LIBUNWIND_TRACE_UNWINDING(
           " _backtrace: start_ip=0x%llX, func=%s, lsda=0x%llX, context=%p\n",
-          frameInfo.start_ip, functionName, frameInfo.lsda, &cursor);
+          (long long)frameInfo.start_ip, functionName, (long long)frameInfo.lsda,
+          &cursor);
     }
 
     // call trace function with this frame
diff --git a/libcxxabi/src/Unwind/UnwindLevel1.c b/libcxxabi/src/Unwind/UnwindLevel1.c
index b2e93c7e8bc..2bb3eb83c28 100644
--- a/libcxxabi/src/Unwind/UnwindLevel1.c
+++ b/libcxxabi/src/Unwind/UnwindLevel1.c
@@ -22,10 +22,10 @@
 #include "unwind.h"
 #include "config.h"
 
-#if _LIBUNWIND_BUILD_ZERO_COST_APIS
+#if _LIBUNWIND_BUILD_ZERO_COST_APIS && !LIBCXXABI_ARM_EHABI
 
 static _Unwind_Reason_Code
-unwind_phase1(unw_context_t *uc, struct _Unwind_Exception *exception_object) {
+unwind_phase1(unw_context_t *uc, _Unwind_Exception *exception_object) {
   unw_cursor_t cursor1;
   unw_init_local(&cursor1, uc);
 
@@ -117,7 +117,7 @@ unwind_phase1(unw_context_t *uc, struct _Unwind_Exception *exception_object) {
 
 
 static _Unwind_Reason_Code
-unwind_phase2(unw_context_t *uc, struct _Unwind_Exception *exception_object) {
+unwind_phase2(unw_context_t *uc, _Unwind_Exception *exception_object) {
   unw_cursor_t cursor2;
   unw_init_local(&cursor2, uc);
 
@@ -187,7 +187,7 @@ unwind_phase2(unw_context_t *uc, struct _Unwind_Exception *exception_object) {
         if (sp == exception_object->private_2) {
           // 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 if phase2 it did not stop here");
+                           "stop here, but now in phase2 it did not stop here");
         }
         break;
       case _URC_INSTALL_CONTEXT:
@@ -202,7 +202,7 @@ unwind_phase2(unw_context_t *uc, struct _Unwind_Exception *exception_object) {
           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",
-                                    exception_object, pc, sp);
+                                     exception_object, pc, sp);
         }
         unw_resume(&cursor2);
         // unw_resume() only returns if there was an error.
@@ -223,7 +223,7 @@ unwind_phase2(unw_context_t *uc, struct _Unwind_Exception *exception_object) {
 
 static _Unwind_Reason_Code
 unwind_phase2_forced(unw_context_t *uc,
-                     struct _Unwind_Exception *exception_object,
+                     _Unwind_Exception *exception_object,
                      _Unwind_Stop_Fn stop, void *stop_parameter) {
   unw_cursor_t cursor2;
   unw_init_local(&cursor2, uc);
@@ -237,7 +237,7 @@ unwind_phase2_forced(unw_context_t *uc,
       _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): unw_step "
                                  "failed => _URC_END_OF_STACK\n",
                                  exception_object);
-      return _URC_FATAL_PHASE1_ERROR;
+      return _URC_FATAL_PHASE2_ERROR;
     }
 
     // When tracing, print state information.
@@ -324,7 +324,7 @@ unwind_phase2_forced(unw_context_t *uc,
 
 /// Called by __cxa_throw.  Only returns if there is a fatal error.
 _LIBUNWIND_EXPORT _Unwind_Reason_Code
-_Unwind_RaiseException(struct _Unwind_Exception *exception_object) {
+_Unwind_RaiseException(_Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_API("_Unwind_RaiseException(ex_obj=%p)\n",
                              exception_object);
   unw_context_t uc;
@@ -358,7 +358,7 @@ _Unwind_RaiseException(struct _Unwind_Exception *exception_object) {
 /// is implemented by having the code call __cxa_rethrow() which
 /// in turn calls _Unwind_Resume_or_Rethrow().
 _LIBUNWIND_EXPORT void
-_Unwind_Resume(struct _Unwind_Exception *exception_object) {
+_Unwind_Resume(_Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_API("_Unwind_Resume(ex_obj=%p)\n", exception_object);
   unw_context_t uc;
   unw_getcontext(&uc);
@@ -380,7 +380,7 @@ _Unwind_Resume(struct _Unwind_Exception *exception_object) {
 /// Unwinds stack, calling "stop" function at each frame.
 /// Could be used to implement longjmp().
 _LIBUNWIND_EXPORT _Unwind_Reason_Code
-_Unwind_ForcedUnwind(struct _Unwind_Exception *exception_object,
+_Unwind_ForcedUnwind(_Unwind_Exception *exception_object,
                      _Unwind_Stop_Fn stop, void *stop_parameter) {
   _LIBUNWIND_TRACE_API("_Unwind_ForcedUnwind(ex_obj=%p, stop=%p)\n",
                   exception_object, stop);
@@ -484,7 +484,7 @@ _Unwind_GetRegionStart(struct _Unwind_Context *context) {
 /// Called by personality handler during phase 2 if a foreign exception
 // is caught.
 _LIBUNWIND_EXPORT void
-_Unwind_DeleteException(struct _Unwind_Exception *exception_object) {
+_Unwind_DeleteException(_Unwind_Exception *exception_object) {
   _LIBUNWIND_TRACE_API("_Unwind_DeleteException(ex_obj=%p)\n",
                               exception_object);
   if (exception_object->exception_cleanup != NULL)
@@ -492,4 +492,4 @@ _Unwind_DeleteException(struct _Unwind_Exception *exception_object) {
                                            exception_object);
 }
 
-#endif // _LIBUNWIND_BUILD_ZERO_COST_APIS
+#endif // _LIBUNWIND_BUILD_ZERO_COST_APIS && !LIBCXXABI_ARM_EHABI
diff --git a/libcxxabi/src/Unwind/UnwindRegistersRestore.S b/libcxxabi/src/Unwind/UnwindRegistersRestore.S
index cf36e7d1a45..1feb1d535fd 100644
--- a/libcxxabi/src/Unwind/UnwindRegistersRestore.S
+++ b/libcxxabi/src/Unwind/UnwindRegistersRestore.S
@@ -311,13 +311,13 @@ DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind15Registers_arm646jumptoEv)
 #elif __arm__
 
 @
-@ void libunwind::Registers_arm::jumpto()
+@ void libunwind::Registers_arm::restoreCoreAndJumpTo()
 @
 @ On entry:
 @  thread_state pointer is in r0
 @
   .p2align 2
-DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm6jumptoEv)
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm20restoreCoreAndJumpToEv)
   @ Use lr as base so that r0 can be restored.
   mov lr, r0
   @ 32bit thumb-2 restrictions for ldm:
@@ -326,6 +326,90 @@ DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm6jumptoEv)
   ldm lr, {r0-r12}
   ldr sp, [lr, #52]
   ldr lr, [lr, #60]  @ restore pc into lr
+#if _ARM_ARCH > 4
+  bx lr
+#else
+  mov pc, lr
+#endif
+
+@
+@ static void libunwind::Registers_arm::restoreVFPWithFLDMD(unw_fpreg_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm19restoreVFPWithFLDMDEPy)
+  @ VFP and iwMMX instructions are only available when compiling with the flags
+  @ that enable them. We don't want to do that in the library (because we don't
+  @ want the compiler to generate instructions that access those) but this is
+  @ only accessed if the personality routine needs these registers. Use of
+  @ these registers implies they are, actually, available on the target, so
+  @ it's ok to execute.
+  @ So, generate the instruction using the corresponding coprocessor mnemonic.
+  ldc p11, cr0, [r0], {#0x20}  @ fldmiad r0, {d0-d15}
+  mov pc, lr
+
+@
+@ static void libunwind::Registers_arm::restoreVFPWithFLDMX(unw_fpreg_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm19restoreVFPWithFLDMXEPy)
+  ldc p11, cr0, [r0], {#0x21}  @ fldmiax r0, {d0-d15}
+  mov pc, lr
+
+@
+@ static void libunwind::Registers_arm::restoreVFPv3(unw_fpreg_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm12restoreVFPv3EPy)
+  ldcl p11, cr0, [r0], {#0x20}  @ vldm r0, {d16-d31}
+  mov pc, lr
+
+@
+@ static void libunwind::Registers_arm::restoreiWMMX(unw_fpreg_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm12restoreiWMMXEPy)
+  ldcl p1, cr0, [r0], #8  @ wldrd wR0, [r0], #8
+  ldcl p1, cr1, [r0], #8  @ wldrd wR1, [r0], #8
+  ldcl p1, cr2, [r0], #8  @ wldrd wR2, [r0], #8
+  ldcl p1, cr3, [r0], #8  @ wldrd wR3, [r0], #8
+  ldcl p1, cr4, [r0], #8  @ wldrd wR4, [r0], #8
+  ldcl p1, cr5, [r0], #8  @ wldrd wR5, [r0], #8
+  ldcl p1, cr6, [r0], #8  @ wldrd wR6, [r0], #8
+  ldcl p1, cr7, [r0], #8  @ wldrd wR7, [r0], #8
+  ldcl p1, cr8, [r0], #8  @ wldrd wR8, [r0], #8
+  ldcl p1, cr9, [r0], #8  @ wldrd wR9, [r0], #8
+  ldcl p1, cr10, [r0], #8  @ wldrd wR10, [r0], #8
+  ldcl p1, cr11, [r0], #8  @ wldrd wR11, [r0], #8
+  ldcl p1, cr12, [r0], #8  @ wldrd wR12, [r0], #8
+  ldcl p1, cr13, [r0], #8  @ wldrd wR13, [r0], #8
+  ldcl p1, cr14, [r0], #8  @ wldrd wR14, [r0], #8
+  ldcl p1, cr15, [r0], #8  @ wldrd wR15, [r0], #8
+  mov pc, lr
+
+@
+@ static void libunwind::Registers_arm::restoreiWMMXControl(unw_uint32_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm19restoreiWMMXControlEPj)
+  ldc2 p1, cr8, [r0], #4  @ wldrw wCGR0, [r0], #4
+  ldc2 p1, cr9, [r0], #4  @ wldrw wCGR1, [r0], #4
+  ldc2 p1, cr10, [r0], #4  @ wldrw wCGR2, [r0], #4
+  ldc2 p1, cr11, [r0], #4  @ wldrw wCGR3, [r0], #4
   mov pc, lr
 
 #endif
diff --git a/libcxxabi/src/Unwind/UnwindRegistersSave.S b/libcxxabi/src/Unwind/UnwindRegistersSave.S
index a3617ed14aa..d23c81644c9 100644
--- a/libcxxabi/src/Unwind/UnwindRegistersSave.S
+++ b/libcxxabi/src/Unwind/UnwindRegistersSave.S
@@ -287,6 +287,12 @@ DEFINE_LIBUNWIND_FUNCTION(unw_getcontext)
 @
 @ On entry:
 @  thread_state pointer is in r0
+@ 
+@ Per EHABI #4.7 this only saves the core integer registers.
+@ EHABI #7.4.5 notes that in general all VRS registers should be restored
+@ however this is very hard to do for VFP registers because it is unknown
+@ to the lbirary how many registers are implemented by the architecture.
+@ Instead, VFP registers are demand saved by logic external to unw_getcontext.
 @
   .p2align 2
 DEFINE_LIBUNWIND_FUNCTION(unw_getcontext)
@@ -297,7 +303,91 @@ DEFINE_LIBUNWIND_FUNCTION(unw_getcontext)
   str sp, [r0, #52]
   str lr, [r0, #56]
   str lr, [r0, #60]  @ store return address as pc
-  mov r0, #0      @ return UNW_ESUCCESS
+  mov r0, #0         @ return UNW_ESUCCESS
+#if _ARM_ARCH > 4
+  bx lr
+#else
+  mov pc, lr
+#endif
+
+@
+@ static void libunwind::Registers_arm::saveVFPWithFSTMD(unw_fpreg_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm16saveVFPWithFSTMDEPy)
+  stc p11, cr0, [r0], {#0x20}  @ fstmiad r0, {d0-d15}
+  mov pc, lr
+
+@
+@ static void libunwind::Registers_arm::saveVFPWithFSTMX(unw_fpreg_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm16saveVFPWithFSTMXEPy)
+  stc p11, cr0, [r0], {#0x21}  @ fstmiax r0, {d0-d15}
+  mov pc, lr
+
+@
+@ static void libunwind::Registers_arm::saveVFPv3(unw_fpreg_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm9saveVFPv3EPy)
+  @ VFP and iwMMX instructions are only available when compiling with the flags
+  @ that enable them. We don't want to do that in the library (because we don't
+  @ want the compiler to generate instructions that access those) but this is
+  @ only accessed if the personality routine needs these registers. Use of
+  @ these registers implies they are, actually, available on the target, so
+  @ it's ok to execute.
+  @ So, generate the instructions using the corresponding coprocessor mnemonic.
+  stcl p11, cr0, [r0], {#0x20}  @ vldm r0, {d16-d31}
+  mov pc, lr
+
+@
+@ static void libunwind::Registers_arm::saveiWMMX(unw_fpreg_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm9saveiWMMXEPy)
+  stcl p1, cr0, [r0], #8  @ wstrd wR0, [r0], #8
+  stcl p1, cr1, [r0], #8  @ wstrd wR1, [r0], #8
+  stcl p1, cr2, [r0], #8  @ wstrd wR2, [r0], #8
+  stcl p1, cr3, [r0], #8  @ wstrd wR3, [r0], #8
+  stcl p1, cr4, [r0], #8  @ wstrd wR4, [r0], #8
+  stcl p1, cr5, [r0], #8  @ wstrd wR5, [r0], #8
+  stcl p1, cr6, [r0], #8  @ wstrd wR6, [r0], #8
+  stcl p1, cr7, [r0], #8  @ wstrd wR7, [r0], #8
+  stcl p1, cr8, [r0], #8  @ wstrd wR8, [r0], #8
+  stcl p1, cr9, [r0], #8  @ wstrd wR9, [r0], #8
+  stcl p1, cr10, [r0], #8  @ wstrd wR10, [r0], #8
+  stcl p1, cr11, [r0], #8  @ wstrd wR11, [r0], #8
+  stcl p1, cr12, [r0], #8  @ wstrd wR12, [r0], #8
+  stcl p1, cr13, [r0], #8  @ wstrd wR13, [r0], #8
+  stcl p1, cr14, [r0], #8  @ wstrd wR14, [r0], #8
+  stcl p1, cr15, [r0], #8  @ wstrd wR15, [r0], #8
+  mov pc, lr
+
+@
+@ static void libunwind::Registers_arm::saveiWMMXControl(unw_uint32_t* values)
+@
+@ On entry:
+@  values pointer is in r0
+@
+  .p2align 2
+DEFINE_LIBUNWIND_PRIVATE_FUNCTION(_ZN9libunwind13Registers_arm16saveiWMMXControlEPj)
+  stc2 p1, cr8, [r0], #4  @ wstrw wCGR0, [r0], #4
+  stc2 p1, cr9, [r0], #4  @ wstrw wCGR1, [r0], #4
+  stc2 p1, cr10, [r0], #4  @ wstrw wCGR2, [r0], #4
+  stc2 p1, cr11, [r0], #4  @ wstrw wCGR3, [r0], #4
   mov pc, lr
 
 #endif
diff --git a/libcxxabi/src/Unwind/libunwind.cpp b/libcxxabi/src/Unwind/libunwind.cpp
index 03d7966f310..b80beaf2308 100644
--- a/libcxxabi/src/Unwind/libunwind.cpp
+++ b/libcxxabi/src/Unwind/libunwind.cpp
@@ -12,11 +12,16 @@
 
 #include <libunwind.h>
 
+#ifndef NDEBUG
+#include <cstdlib> // getenv
+#endif
 #include <new>
 
 #include "libunwind_ext.h"
 #include "config.h"
 
+#include <stdlib.h>
+
 
 #if _LIBUNWIND_BUILD_ZERO_COST_APIS
 
@@ -50,6 +55,9 @@ _LIBUNWIND_EXPORT int unw_init_local(unw_cursor_t *cursor,
 #elif __arm64__
   new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_arm64>(
                                  context, LocalAddressSpace::sThisAddressSpace);
+#elif LIBCXXABI_ARM_EHABI
+  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_arm>(
+                                 context, LocalAddressSpace::sThisAddressSpace);
 #endif
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   co->setInfoBasedOnIPRegister();
@@ -161,7 +169,7 @@ _LIBUNWIND_EXPORT int unw_get_reg(unw_cursor_t *cursor, unw_regnum_t regNum,
 _LIBUNWIND_EXPORT int unw_set_reg(unw_cursor_t *cursor, unw_regnum_t regNum,
                                   unw_word_t value) {
   _LIBUNWIND_TRACE_API("unw_set_reg(cursor=%p, regNum=%d, value=0x%llX)\n",
-                             cursor, regNum, value);
+                       cursor, regNum, (long long)value);
   typedef LocalAddressSpace::pint_t pint_t;
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   if (co->validReg(regNum)) {
@@ -193,8 +201,13 @@ _LIBUNWIND_EXPORT int unw_get_fpreg(unw_cursor_t *cursor, unw_regnum_t regNum,
 /// Set value of specified float register at cursor position in stack frame.
 _LIBUNWIND_EXPORT int unw_set_fpreg(unw_cursor_t *cursor, unw_regnum_t regNum,
                                     unw_fpreg_t value) {
+#if LIBCXXABI_ARM_EHABI
+  _LIBUNWIND_TRACE_API("unw_set_fpreg(cursor=%p, regNum=%d, value=%llX)\n",
+                       cursor, regNum, value);
+#else
   _LIBUNWIND_TRACE_API("unw_set_fpreg(cursor=%p, regNum=%d, value=%g)\n",
-                             cursor, regNum, value);
+                       cursor, regNum, value);
+#endif
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   if (co->validFloatReg(regNum)) {
     co->setFloatReg(regNum, value);
@@ -239,7 +252,7 @@ _LIBUNWIND_EXPORT int unw_resume(unw_cursor_t *cursor) {
 _LIBUNWIND_EXPORT int unw_get_proc_name(unw_cursor_t *cursor, char *buf,
                                         size_t bufLen, unw_word_t *offset) {
   _LIBUNWIND_TRACE_API("unw_get_proc_name(cursor=%p, &buf=%p,"
-                             "bufLen=%ld)\n", cursor, buf, bufLen);
+                             "bufLen=%zu)\n", cursor, buf, bufLen);
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   if (co->getFunctionName(buf, bufLen, offset))
     return UNW_ESUCCESS;
@@ -274,6 +287,15 @@ _LIBUNWIND_EXPORT int unw_is_signal_frame(unw_cursor_t *cursor) {
   return co->isSignalFrame();
 }
 
+#if __arm__
+// Save VFP registers d0-d15 using FSTMIADX instead of FSTMIADD
+_LIBUNWIND_EXPORT void unw_save_vfp_as_X(unw_cursor_t *cursor) {
+  _LIBUNWIND_TRACE_API("unw_fpreg_save_vfp_as_X(cursor=%p)\n", cursor);
+  AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
+  return co->saveVFPAsX();
+}
+#endif
+
 
 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND
 /// SPI: walks cached dwarf entries