vendor/llvm-project/llvmorg-11-init-20887-g2e10b7a39b9vendor/llvm-project/master

17 files changed, 750 insertions, 183 deletions

diff --git a/libunwind/src/AddressSpace.hpp b/libunwind/src/AddressSpace.hpp
index 7433476f9117..a4564cb67328 100644
--- a/libunwind/src/AddressSpace.hpp
+++ b/libunwind/src/AddressSpace.hpp
@@ -392,6 +392,164 @@ LocalAddressSpace::getEncodedP(pint_t &addr, pint_t end, uint8_t encoding,
   return result;
 }
 
+#ifdef __APPLE__
+#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_LIBUNWIND_IS_BAREMETAL)
+#elif defined(_LIBUNWIND_ARM_EHABI) && defined(_LIBUNWIND_IS_BAREMETAL)
+#elif defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) && defined(_WIN32)
+#elif defined(_LIBUNWIND_SUPPORT_SEH_UNWIND) && defined(_WIN32)
+#elif defined(_LIBUNWIND_ARM_EHABI) && defined(__BIONIC__)
+// Code inside findUnwindSections handles all these cases.
+//
+// Although the above ifdef chain is ugly, there doesn't seem to be a cleaner
+// way to handle it. The generalized boolean expression is:
+//
+//  A OR (B AND C) OR (D AND C) OR (B AND E) OR (F AND E) OR (D AND G)
+//
+// Running it through various boolean expression simplifiers gives expressions
+// that don't help at all.
+#elif defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
+
+#if !defined(Elf_Half)
+  typedef ElfW(Half) Elf_Half;
+#endif
+#if !defined(Elf_Phdr)
+  typedef ElfW(Phdr) Elf_Phdr;
+#endif
+#if !defined(Elf_Addr)
+  typedef ElfW(Addr) Elf_Addr;
+#endif
+
+static Elf_Addr calculateImageBase(struct dl_phdr_info *pinfo) {
+  Elf_Addr image_base = pinfo->dlpi_addr;
+#if defined(__ANDROID__) && __ANDROID_API__ < 18
+  if (image_base == 0) {
+    // Normally, an image base of 0 indicates a non-PIE executable. On
+    // versions of Android prior to API 18, the dynamic linker reported a
+    // dlpi_addr of 0 for PIE executables. Compute the true image base
+    // using the PT_PHDR segment.
+    // See https://github.com/android/ndk/issues/505.
+    for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
+      const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
+      if (phdr->p_type == PT_PHDR) {
+        image_base = reinterpret_cast<Elf_Addr>(pinfo->dlpi_phdr) -
+          phdr->p_vaddr;
+        break;
+      }
+    }
+  }
+#endif
+  return image_base;
+}
+
+struct _LIBUNWIND_HIDDEN dl_iterate_cb_data {
+  LocalAddressSpace *addressSpace;
+  UnwindInfoSections *sects;
+  uintptr_t targetAddr;
+};
+
+#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
+  #if !defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
+    #error "_LIBUNWIND_SUPPORT_DWARF_UNWIND requires _LIBUNWIND_SUPPORT_DWARF_INDEX on this platform."
+  #endif
+
+#include "FrameHeaderCache.hpp"
+
+// There should be just one of these per process.
+static FrameHeaderCache ProcessFrameHeaderCache;
+
+static bool checkAddrInSegment(const Elf_Phdr *phdr, size_t image_base,
+                               dl_iterate_cb_data *cbdata) {
+  if (phdr->p_type == PT_LOAD) {
+    uintptr_t begin = image_base + phdr->p_vaddr;
+    uintptr_t end = begin + phdr->p_memsz;
+    if (cbdata->targetAddr >= begin && cbdata->targetAddr < end) {
+      cbdata->sects->dso_base = begin;
+      cbdata->sects->dwarf_section_length = phdr->p_memsz;
+      return true;
+    }
+  }
+  return false;
+}
+
+int findUnwindSectionsByPhdr(struct dl_phdr_info *pinfo, size_t pinfo_size,
+                             void *data) {
+  auto cbdata = static_cast<dl_iterate_cb_data *>(data);
+  if (pinfo->dlpi_phnum == 0 || cbdata->targetAddr < pinfo->dlpi_addr)
+    return 0;
+  if (ProcessFrameHeaderCache.find(pinfo, pinfo_size, data))
+    return 1;
+
+  Elf_Addr image_base = calculateImageBase(pinfo);
+  bool found_obj = false;
+  bool found_hdr = false;
+
+  // Third phdr is usually the executable phdr.
+  if (pinfo->dlpi_phnum > 2)
+    found_obj = checkAddrInSegment(&pinfo->dlpi_phdr[2], image_base, cbdata);
+
+  // PT_GNU_EH_FRAME is usually near the end. Iterate backward. We already know
+  // that there is one or more phdrs.
+  for (Elf_Half i = pinfo->dlpi_phnum; i > 0; i--) {
+    const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i - 1];
+    if (!found_hdr && phdr->p_type == PT_GNU_EH_FRAME) {
+      EHHeaderParser<LocalAddressSpace>::EHHeaderInfo hdrInfo;
+      uintptr_t eh_frame_hdr_start = image_base + phdr->p_vaddr;
+      cbdata->sects->dwarf_index_section = eh_frame_hdr_start;
+      cbdata->sects->dwarf_index_section_length = phdr->p_memsz;
+      found_hdr = EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
+          *cbdata->addressSpace, eh_frame_hdr_start, phdr->p_memsz,
+          hdrInfo);
+      if (found_hdr)
+        cbdata->sects->dwarf_section = hdrInfo.eh_frame_ptr;
+    } else if (!found_obj) {
+      found_obj = checkAddrInSegment(phdr, image_base, cbdata);
+    }
+    if (found_obj && found_hdr) {
+      ProcessFrameHeaderCache.add(cbdata->sects);
+      return 1;
+    }
+  }
+  cbdata->sects->dwarf_section_length = 0;
+  return 0;
+}
+
+#else  // defined(LIBUNWIND_SUPPORT_DWARF_UNWIND)
+// Given all the #ifdef's above, the code here is for
+// defined(LIBUNWIND_ARM_EHABI)
+
+int findUnwindSectionsByPhdr(struct dl_phdr_info *pinfo, size_t, void *data) {
+  auto *cbdata = static_cast<dl_iterate_cb_data *>(data);
+  bool found_obj = false;
+  bool found_hdr = false;
+
+  assert(cbdata);
+  assert(cbdata->sects);
+
+  if (cbdata->targetAddr < pinfo->dlpi_addr)
+    return 0;
+
+  Elf_Addr image_base = calculateImageBase(pinfo);
+
+  for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
+    const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
+    if (phdr->p_type == PT_LOAD) {
+      uintptr_t begin = image_base + phdr->p_vaddr;
+      uintptr_t end = begin + phdr->p_memsz;
+      if (cbdata->targetAddr >= begin && cbdata->targetAddr < end)
+        found_obj = true;
+    } else if (phdr->p_type == PT_ARM_EXIDX) {
+      uintptr_t exidx_start = image_base + phdr->p_vaddr;
+      cbdata->sects->arm_section = exidx_start;
+      cbdata->sects->arm_section_length = phdr->p_memsz;
+      found_hdr = true;
+    }
+  }
+  return found_obj && found_hdr;
+}
+#endif  // defined(LIBUNWIND_SUPPORT_DWARF_UNWIND)
+#endif  // defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
+
+
 inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
                                                   UnwindInfoSections &info) {
 #ifdef __APPLE__
@@ -483,110 +641,8 @@ inline bool LocalAddressSpace::findUnwindSections(pint_t targetAddr,
   if (info.arm_section && info.arm_section_length)
     return true;
 #elif defined(_LIBUNWIND_ARM_EHABI) || defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
-  struct dl_iterate_cb_data {
-    LocalAddressSpace *addressSpace;
-    UnwindInfoSections *sects;
-    uintptr_t targetAddr;
-  };
-
   dl_iterate_cb_data cb_data = {this, &info, targetAddr};
-  int found = dl_iterate_phdr(
-      [](struct dl_phdr_info *pinfo, size_t, void *data) -> int {
-        auto cbdata = static_cast<dl_iterate_cb_data *>(data);
-        bool found_obj = false;
-        bool found_hdr = false;
-
-        assert(cbdata);
-        assert(cbdata->sects);
-
-        if (cbdata->targetAddr < pinfo->dlpi_addr) {
-          return false;
-        }
-
-#if !defined(Elf_Half)
-        typedef ElfW(Half) Elf_Half;
-#endif
-#if !defined(Elf_Phdr)
-        typedef ElfW(Phdr) Elf_Phdr;
-#endif
-#if !defined(Elf_Addr)
-        typedef ElfW(Addr) Elf_Addr;
-#endif
-
-        Elf_Addr image_base = pinfo->dlpi_addr;
-
-#if defined(__ANDROID__) && __ANDROID_API__ < 18
-        if (image_base == 0) {
-          // Normally, an image base of 0 indicates a non-PIE executable. On
-          // versions of Android prior to API 18, the dynamic linker reported a
-          // dlpi_addr of 0 for PIE executables. Compute the true image base
-          // using the PT_PHDR segment.
-          // See https://github.com/android/ndk/issues/505.
-          for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
-            const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
-            if (phdr->p_type == PT_PHDR) {
-              image_base = reinterpret_cast<Elf_Addr>(pinfo->dlpi_phdr) -
-                  phdr->p_vaddr;
-              break;
-            }
-          }
-        }
-#endif
-
- #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)
-  #if !defined(_LIBUNWIND_SUPPORT_DWARF_INDEX)
-   #error "_LIBUNWIND_SUPPORT_DWARF_UNWIND requires _LIBUNWIND_SUPPORT_DWARF_INDEX on this platform."
-  #endif
-        size_t object_length;
-
-        for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
-          const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
-          if (phdr->p_type == PT_LOAD) {
-            uintptr_t begin = image_base + phdr->p_vaddr;
-            uintptr_t end = begin + phdr->p_memsz;
-            if (cbdata->targetAddr >= begin && cbdata->targetAddr < end) {
-              cbdata->sects->dso_base = begin;
-              object_length = phdr->p_memsz;
-              found_obj = true;
-            }
-          } else if (phdr->p_type == PT_GNU_EH_FRAME) {
-            EHHeaderParser<LocalAddressSpace>::EHHeaderInfo hdrInfo;
-            uintptr_t eh_frame_hdr_start = image_base + phdr->p_vaddr;
-            cbdata->sects->dwarf_index_section = eh_frame_hdr_start;
-            cbdata->sects->dwarf_index_section_length = phdr->p_memsz;
-            found_hdr = EHHeaderParser<LocalAddressSpace>::decodeEHHdr(
-                *cbdata->addressSpace, eh_frame_hdr_start, phdr->p_memsz,
-                hdrInfo);
-            if (found_hdr)
-              cbdata->sects->dwarf_section = hdrInfo.eh_frame_ptr;
-          }
-        }
-
-        if (found_obj && found_hdr) {
-          cbdata->sects->dwarf_section_length = object_length;
-          return true;
-        } else {
-          return false;
-        }
- #else // defined(_LIBUNWIND_ARM_EHABI)
-        for (Elf_Half i = 0; i < pinfo->dlpi_phnum; i++) {
-          const Elf_Phdr *phdr = &pinfo->dlpi_phdr[i];
-          if (phdr->p_type == PT_LOAD) {
-            uintptr_t begin = image_base + phdr->p_vaddr;
-            uintptr_t end = begin + phdr->p_memsz;
-            if (cbdata->targetAddr >= begin && cbdata->targetAddr < end)
-              found_obj = true;
-          } else if (phdr->p_type == PT_ARM_EXIDX) {
-            uintptr_t exidx_start = image_base + phdr->p_vaddr;
-            cbdata->sects->arm_section = exidx_start;
-            cbdata->sects->arm_section_length = phdr->p_memsz;
-            found_hdr = true;
-          }
-        }
-        return found_obj && found_hdr;
- #endif
-      },
-      &cb_data);
+  int found = dl_iterate_phdr(findUnwindSectionsByPhdr, &cb_data);
   return static_cast<bool>(found);
 #endif
 
diff --git a/libunwind/src/DwarfParser.hpp b/libunwind/src/DwarfParser.hpp
index df69c2a4bd23..d05ac468367f 100644
--- a/libunwind/src/DwarfParser.hpp
+++ b/libunwind/src/DwarfParser.hpp
@@ -77,6 +77,7 @@ public:
   };
   struct RegisterLocation {
     RegisterSavedWhere location;
+    bool initialStateSaved;
     int64_t value;
   };
   /// Information about a frame layout and registers saved determined
@@ -90,6 +91,40 @@ public:
     bool              registersInOtherRegisters;
     bool              sameValueUsed;
     RegisterLocation  savedRegisters[kMaxRegisterNumber + 1];
+    enum class InitializeTime { kLazy, kNormal };
+
+    // When saving registers, this data structure is lazily initialized.
+    PrologInfo(InitializeTime IT = InitializeTime::kNormal) {
+      if (IT == InitializeTime::kNormal)
+        memset(this, 0, sizeof(*this));
+    }
+    void checkSaveRegister(uint64_t reg, PrologInfo &initialState) {
+      if (!savedRegisters[reg].initialStateSaved) {
+        initialState.savedRegisters[reg] = savedRegisters[reg];
+        savedRegisters[reg].initialStateSaved = true;
+      }
+    }
+    void setRegister(uint64_t reg, RegisterSavedWhere newLocation,
+                     int64_t newValue, PrologInfo &initialState) {
+      checkSaveRegister(reg, initialState);
+      savedRegisters[reg].location = newLocation;
+      savedRegisters[reg].value = newValue;
+    }
+    void setRegisterLocation(uint64_t reg, RegisterSavedWhere newLocation,
+                             PrologInfo &initialState) {
+      checkSaveRegister(reg, initialState);
+      savedRegisters[reg].location = newLocation;
+    }
+    void setRegisterValue(uint64_t reg, int64_t newValue,
+                          PrologInfo &initialState) {
+      checkSaveRegister(reg, initialState);
+      savedRegisters[reg].value = newValue;
+    }
+    void restoreRegisterToInitialState(uint64_t reg, PrologInfo &initialState) {
+      if (savedRegisters[reg].initialStateSaved)
+        savedRegisters[reg] = initialState.savedRegisters[reg];
+      // else the register still holds its initial state
+    }
   };
 
   struct PrologInfoStackEntry {
@@ -355,18 +390,30 @@ bool CFI_Parser<A>::parseFDEInstructions(A &addressSpace,
                                          const FDE_Info &fdeInfo,
                                          const CIE_Info &cieInfo, pint_t upToPC,
                                          int arch, PrologInfo *results) {
-  // clear results
-  memset(results, '\0', sizeof(PrologInfo));
   PrologInfoStackEntry *rememberStack = NULL;
 
   // parse CIE then FDE instructions
-  return parseInstructions(addressSpace, cieInfo.cieInstructions,
-                           cieInfo.cieStart + cieInfo.cieLength, cieInfo,
-                           (pint_t)(-1), rememberStack, arch, results) &&
-         parseInstructions(addressSpace, fdeInfo.fdeInstructions,
-                           fdeInfo.fdeStart + fdeInfo.fdeLength, cieInfo,
-                           upToPC - fdeInfo.pcStart, rememberStack, arch,
-                           results);
+  bool returnValue =
+      parseInstructions(addressSpace, cieInfo.cieInstructions,
+                        cieInfo.cieStart + cieInfo.cieLength, cieInfo,
+                        (pint_t)(-1), rememberStack, arch, results) &&
+      parseInstructions(addressSpace, fdeInfo.fdeInstructions,
+                        fdeInfo.fdeStart + fdeInfo.fdeLength, cieInfo,
+                        upToPC - fdeInfo.pcStart, rememberStack, arch, results);
+
+#if !defined(_LIBUNWIND_NO_HEAP)
+  // Clean up rememberStack. Even in the case where every DW_CFA_remember_state
+  // is paired with a DW_CFA_restore_state, parseInstructions can skip restore
+  // opcodes if it reaches the target PC and stops interpreting, so we have to
+  // make sure we don't leak memory.
+  while (rememberStack) {
+    PrologInfoStackEntry *next = rememberStack->next;
+    free(rememberStack);
+    rememberStack = next;
+  }
+#endif
+
+  return returnValue;
 }
 
 /// "run" the DWARF instructions
@@ -378,7 +425,9 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
                                       int arch, PrologInfo *results) {
   pint_t p = instructions;
   pint_t codeOffset = 0;
-  PrologInfo initialState = *results;
+  // initialState initialized as registers in results are modified. Use
+  // PrologInfo accessor functions to avoid reading uninitialized data.
+  PrologInfo initialState(PrologInfo::InitializeTime::kLazy);
 
   _LIBUNWIND_TRACE_DWARF("parseInstructions(instructions=0x%0" PRIx64 ")\n",
                          static_cast<uint64_t>(instructionsEnd));
@@ -431,8 +480,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
                 "malformed DW_CFA_offset_extended DWARF unwind, reg too big");
         return false;
       }
-      results->savedRegisters[reg].location = kRegisterInCFA;
-      results->savedRegisters[reg].value = offset;
+      results->setRegister(reg, kRegisterInCFA, offset, initialState);
       _LIBUNWIND_TRACE_DWARF("DW_CFA_offset_extended(reg=%" PRIu64 ", "
                              "offset=%" PRId64 ")\n",
                              reg, offset);
@@ -444,7 +492,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
             "malformed DW_CFA_restore_extended DWARF unwind, reg too big");
         return false;
       }
-      results->savedRegisters[reg] = initialState.savedRegisters[reg];
+      results->restoreRegisterToInitialState(reg, initialState);
       _LIBUNWIND_TRACE_DWARF("DW_CFA_restore_extended(reg=%" PRIu64 ")\n", reg);
       break;
     case DW_CFA_undefined:
@@ -454,7 +502,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
                 "malformed DW_CFA_undefined DWARF unwind, reg too big");
         return false;
       }
-      results->savedRegisters[reg].location = kRegisterUnused;
+      results->setRegisterLocation(reg, kRegisterUnused, initialState);
       _LIBUNWIND_TRACE_DWARF("DW_CFA_undefined(reg=%" PRIu64 ")\n", reg);
       break;
     case DW_CFA_same_value:
@@ -468,7 +516,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
       // "same value" means register was stored in frame, but its current
       // value has not changed, so no need to restore from frame.
       // We model this as if the register was never saved.
-      results->savedRegisters[reg].location = kRegisterUnused;
+      results->setRegisterLocation(reg, kRegisterUnused, initialState);
       // set flag to disable conversion to compact unwind
       results->sameValueUsed = true;
       _LIBUNWIND_TRACE_DWARF("DW_CFA_same_value(reg=%" PRIu64 ")\n", reg);
@@ -486,8 +534,8 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
                 "malformed DW_CFA_register DWARF unwind, reg2 too big");
         return false;
       }
-      results->savedRegisters[reg].location = kRegisterInRegister;
-      results->savedRegisters[reg].value = (int64_t)reg2;
+      results->setRegister(reg, kRegisterInRegister, (int64_t)reg2,
+                           initialState);
       // set flag to disable conversion to compact unwind
       results->registersInOtherRegisters = true;
       _LIBUNWIND_TRACE_DWARF(
@@ -564,8 +612,8 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
                 "malformed DW_CFA_expression DWARF unwind, reg too big");
         return false;
       }
-      results->savedRegisters[reg].location = kRegisterAtExpression;
-      results->savedRegisters[reg].value = (int64_t)p;
+      results->setRegister(reg, kRegisterAtExpression, (int64_t)p,
+                           initialState);
       length = addressSpace.getULEB128(p, instructionsEnd);
       assert(length < static_cast<pint_t>(~0) && "pointer overflow");
       p += static_cast<pint_t>(length);
@@ -583,8 +631,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
       }
       offset =
           addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
-      results->savedRegisters[reg].location = kRegisterInCFA;
-      results->savedRegisters[reg].value = offset;
+      results->setRegister(reg, kRegisterInCFA, offset, initialState);
       _LIBUNWIND_TRACE_DWARF("DW_CFA_offset_extended_sf(reg=%" PRIu64 ", "
                              "offset=%" PRId64 ")\n",
                              reg, offset);
@@ -622,8 +669,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
       }
       offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
                                                     * cieInfo.dataAlignFactor;
-      results->savedRegisters[reg].location = kRegisterOffsetFromCFA;
-      results->savedRegisters[reg].value = offset;
+      results->setRegister(reg, kRegisterOffsetFromCFA, offset, initialState);
       _LIBUNWIND_TRACE_DWARF("DW_CFA_val_offset(reg=%" PRIu64 ", "
                              "offset=%" PRId64 "\n",
                              reg, offset);
@@ -637,8 +683,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
       }
       offset =
           addressSpace.getSLEB128(p, instructionsEnd) * cieInfo.dataAlignFactor;
-      results->savedRegisters[reg].location = kRegisterOffsetFromCFA;
-      results->savedRegisters[reg].value = offset;
+      results->setRegister(reg, kRegisterOffsetFromCFA, offset, initialState);
       _LIBUNWIND_TRACE_DWARF("DW_CFA_val_offset_sf(reg=%" PRIu64 ", "
                              "offset=%" PRId64 "\n",
                              reg, offset);
@@ -650,8 +695,8 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
                 "malformed DW_CFA_val_expression DWARF unwind, reg too big");
         return false;
       }
-      results->savedRegisters[reg].location = kRegisterIsExpression;
-      results->savedRegisters[reg].value = (int64_t)p;
+      results->setRegister(reg, kRegisterIsExpression, (int64_t)p,
+                           initialState);
       length = addressSpace.getULEB128(p, instructionsEnd);
       assert(length < static_cast<pint_t>(~0) && "pointer overflow");
       p += static_cast<pint_t>(length);
@@ -673,8 +718,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
       }
       offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
                                                     * cieInfo.dataAlignFactor;
-      results->savedRegisters[reg].location = kRegisterInCFA;
-      results->savedRegisters[reg].value = -offset;
+      results->setRegister(reg, kRegisterInCFA, -offset, initialState);
       _LIBUNWIND_TRACE_DWARF(
           "DW_CFA_GNU_negative_offset_extended(%" PRId64 ")\n", offset);
       break;
@@ -687,25 +731,27 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
     case DW_CFA_AARCH64_negate_ra_state:
       switch (arch) {
 #if defined(_LIBUNWIND_TARGET_AARCH64)
-      case REGISTERS_ARM64:
-        results->savedRegisters[UNW_ARM64_RA_SIGN_STATE].value ^= 0x1;
-        _LIBUNWIND_TRACE_DWARF("DW_CFA_AARCH64_negate_ra_state\n");
-        break;
+        case REGISTERS_ARM64: {
+          int64_t value =
+              results->savedRegisters[UNW_ARM64_RA_SIGN_STATE].value ^ 0x1;
+          results->setRegisterValue(UNW_ARM64_RA_SIGN_STATE, value, initialState);
+          _LIBUNWIND_TRACE_DWARF("DW_CFA_AARCH64_negate_ra_state\n");
+        } break;
 #endif
+
 #if defined(_LIBUNWIND_TARGET_SPARC)
       // case DW_CFA_GNU_window_save:
       case REGISTERS_SPARC:
         _LIBUNWIND_TRACE_DWARF("DW_CFA_GNU_window_save()\n");
         for (reg = UNW_SPARC_O0; reg <= UNW_SPARC_O7; reg++) {
-          results->savedRegisters[reg].location = kRegisterInRegister;
-          results->savedRegisters[reg].value =
-              ((int64_t)reg - UNW_SPARC_O0) + UNW_SPARC_I0;
+          results->setRegister(reg, kRegisterInRegister,
+                               ((int64_t)reg - UNW_SPARC_O0) + UNW_SPARC_I0,
+                               initialState);
         }
 
         for (reg = UNW_SPARC_L0; reg <= UNW_SPARC_I7; reg++) {
-          results->savedRegisters[reg].location = kRegisterInCFA;
-          results->savedRegisters[reg].value =
-              ((int64_t)reg - UNW_SPARC_L0) * 4;
+          results->setRegister(reg, kRegisterInCFA,
+                               ((int64_t)reg - UNW_SPARC_L0) * 4, initialState);
         }
         break;
 #endif
@@ -728,8 +774,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
         }
         offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
                                                     * cieInfo.dataAlignFactor;
-        results->savedRegisters[reg].location = kRegisterInCFA;
-        results->savedRegisters[reg].value = offset;
+        results->setRegister(reg, kRegisterInCFA, offset, initialState);
         _LIBUNWIND_TRACE_DWARF("DW_CFA_offset(reg=%d, offset=%" PRId64 ")\n",
                                operand, offset);
         break;
@@ -746,7 +791,7 @@ bool CFI_Parser<A>::parseInstructions(A &addressSpace, pint_t instructions,
                   reg);
           return false;
         }
-        results->savedRegisters[reg] = initialState.savedRegisters[reg];
+        results->restoreRegisterToInitialState(reg, initialState);
         _LIBUNWIND_TRACE_DWARF("DW_CFA_restore(reg=%" PRIu64 ")\n",
                                static_cast<uint64_t>(operand));
         break;
diff --git a/libunwind/src/EHHeaderParser.hpp b/libunwind/src/EHHeaderParser.hpp
index 0101835b8e63..f97cca54825f 100644
--- a/libunwind/src/EHHeaderParser.hpp
+++ b/libunwind/src/EHHeaderParser.hpp
@@ -109,6 +109,8 @@ bool EHHeaderParser<A>::findFDE(A &addressSpace, pint_t pc, pint_t ehHdrStart,
                                       hdrInfo))
     return false;
 
+  if (hdrInfo.fde_count == 0) return false;
+
   size_t tableEntrySize = getTableEntrySize(hdrInfo.table_enc);
   pint_t tableEntry;
 
diff --git a/libunwind/src/FrameHeaderCache.hpp b/libunwind/src/FrameHeaderCache.hpp
new file mode 100644
index 000000000000..813fcd408b26
--- /dev/null
+++ b/libunwind/src/FrameHeaderCache.hpp
@@ -0,0 +1,149 @@
+//===-FrameHeaderCache.hpp ------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// Cache the elf program headers necessary to unwind the stack more efficiently
+// in the presence of many dsos.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __FRAMEHEADER_CACHE_HPP__
+#define __FRAMEHEADER_CACHE_HPP__
+
+#include "config.h"
+#include <limits.h>
+
+#ifdef _LIBUNWIND_DEBUG_FRAMEHEADER_CACHE
+#define _LIBUNWIND_FRAMEHEADERCACHE_TRACE0(x) _LIBUNWIND_LOG0(x)
+#define _LIBUNWIND_FRAMEHEADERCACHE_TRACE(msg, ...)                            \
+  _LIBUNWIND_LOG(msg, __VA_ARGS__)
+#else
+#define _LIBUNWIND_FRAMEHEADERCACHE_TRACE0(x)
+#define _LIBUNWIND_FRAMEHEADERCACHE_TRACE(msg, ...)
+#endif
+
+// This cache should only be be used from within a dl_iterate_phdr callback.
+// dl_iterate_phdr does the necessary synchronization to prevent problems
+// with concurrent access via the libc load lock. Adding synchronization
+// for other uses is possible, but not currently done.
+
+class _LIBUNWIND_HIDDEN FrameHeaderCache {
+  struct CacheEntry {
+    uintptr_t LowPC() { return Info.dso_base; };
+    uintptr_t HighPC() { return Info.dso_base + Info.dwarf_section_length; };
+    UnwindInfoSections Info;
+    CacheEntry *Next;
+  };
+
+  static const size_t kCacheEntryCount = 8;
+
+  // Can't depend on the C++ standard library in libunwind, so use an array to
+  // allocate the entries, and two linked lists for ordering unused and recently
+  // used entries.  FIXME: Would the the extra memory for a doubly-linked list
+  // be better than the runtime cost of traversing a very short singly-linked
+  // list on a cache miss? The entries themselves are all small and consecutive,
+  // so unlikely to cause page faults when following the pointers. The memory
+  // spent on additional pointers could also be spent on more entries.
+
+  CacheEntry Entries[kCacheEntryCount];
+  CacheEntry *MostRecentlyUsed;
+  CacheEntry *Unused;
+
+  void resetCache() {
+    _LIBUNWIND_FRAMEHEADERCACHE_TRACE0("FrameHeaderCache reset");
+    MostRecentlyUsed = nullptr;
+    Unused = &Entries[0];
+    for (size_t i = 0; i < kCacheEntryCount - 1; i++) {
+      Entries[i].Next = &Entries[i + 1];
+    }
+    Entries[kCacheEntryCount - 1].Next = nullptr;
+  }
+
+  bool cacheNeedsReset(dl_phdr_info *PInfo) {
+    // C libraries increment dl_phdr_info.adds and dl_phdr_info.subs when
+    // loading and unloading shared libraries. If these values change between
+    // iterations of dl_iterate_phdr, then invalidate the cache.
+
+    // These are static to avoid needing an initializer, and unsigned long long
+    // because that is their type within the extended dl_phdr_info.  Initialize
+    // these to something extremely unlikely to be found upon the first call to
+    // dl_iterate_phdr.
+    static unsigned long long LastAdds = ULLONG_MAX;
+    static unsigned long long LastSubs = ULLONG_MAX;
+    if (PInfo->dlpi_adds != LastAdds || PInfo->dlpi_subs != LastSubs) {
+      // Resetting the entire cache is a big hammer, but this path is rare--
+      // usually just on the very first call, when the cache is empty anyway--so
+      // added complexity doesn't buy much.
+      LastAdds = PInfo->dlpi_adds;
+      LastSubs = PInfo->dlpi_subs;
+      resetCache();
+      return true;
+    }
+    return false;
+  }
+
+public:
+  bool find(dl_phdr_info *PInfo, size_t, void *data) {
+    if (cacheNeedsReset(PInfo) || MostRecentlyUsed == nullptr)
+      return false;
+
+    auto *CBData = static_cast<dl_iterate_cb_data *>(data);
+    CacheEntry *Current = MostRecentlyUsed;
+    CacheEntry *Previous = nullptr;
+    while (Current != nullptr) {
+      _LIBUNWIND_FRAMEHEADERCACHE_TRACE(
+          "FrameHeaderCache check %lx in [%lx - %lx)", CBData->targetAddr,
+          Current->LowPC(), Current->HighPC());
+      if (Current->LowPC() <= CBData->targetAddr &&
+          CBData->targetAddr < Current->HighPC()) {
+        _LIBUNWIND_FRAMEHEADERCACHE_TRACE(
+            "FrameHeaderCache hit %lx in [%lx - %lx)", CBData->targetAddr,
+            Current->LowPC(), Current->HighPC());
+        if (Previous) {
+          // If there is no Previous, then Current is already the
+          // MostRecentlyUsed, and no need to move it up.
+          Previous->Next = Current->Next;
+          Current->Next = MostRecentlyUsed;
+          MostRecentlyUsed = Current;
+        }
+        *CBData->sects = Current->Info;
+        return true;
+      }
+      Previous = Current;
+      Current = Current->Next;
+    }
+    _LIBUNWIND_FRAMEHEADERCACHE_TRACE("FrameHeaderCache miss for address %lx",
+                                      CBData->targetAddr);
+    return false;
+  }
+
+  void add(const UnwindInfoSections *UIS) {
+    CacheEntry *Current = nullptr;
+
+    if (Unused != nullptr) {
+      Current = Unused;
+      Unused = Unused->Next;
+    } else {
+      Current = MostRecentlyUsed;
+      CacheEntry *Previous = nullptr;
+      while (Current->Next != nullptr) {
+        Previous = Current;
+        Current = Current->Next;
+      }
+      Previous->Next = nullptr;
+      _LIBUNWIND_FRAMEHEADERCACHE_TRACE("FrameHeaderCache evict [%lx - %lx)",
+                                        Current->LowPC(), Current->HighPC());
+    }
+
+    Current->Info = *UIS;
+    Current->Next = MostRecentlyUsed;
+    MostRecentlyUsed = Current;
+    _LIBUNWIND_FRAMEHEADERCACHE_TRACE("FrameHeaderCache add [%lx - %lx)",
+                                      MostRecentlyUsed->LowPC(),
+                                      MostRecentlyUsed->HighPC());
+  }
+};
+
+#endif // __FRAMEHEADER_CACHE_HPP__
diff --git a/libunwind/src/Registers.hpp b/libunwind/src/Registers.hpp
index 416ed61df74a..c76b05bf314e 100644
--- a/libunwind/src/Registers.hpp
+++ b/libunwind/src/Registers.hpp
@@ -34,6 +34,7 @@ enum {
   REGISTERS_MIPS_O32,
   REGISTERS_MIPS_NEWABI,
   REGISTERS_SPARC,
+  REGISTERS_HEXAGON,
   REGISTERS_RISCV,
 };
 
@@ -2869,6 +2870,8 @@ inline bool Registers_mips_o32::validFloatRegister(int regNum) const {
 #if defined(__mips_hard_float) && __mips_fpr == 64
   if (regNum >= UNW_MIPS_F0 && regNum <= UNW_MIPS_F31)
     return true;
+#else
+  (void)regNum;
 #endif
   return false;
 }
@@ -2878,6 +2881,7 @@ inline double Registers_mips_o32::getFloatRegister(int regNum) const {
   assert(validFloatRegister(regNum));
   return _floats[regNum - UNW_MIPS_F0];
 #else
+  (void)regNum;
   _LIBUNWIND_ABORT("mips_o32 float support not implemented");
 #endif
 }
@@ -2888,6 +2892,8 @@ inline void Registers_mips_o32::setFloatRegister(int regNum,
   assert(validFloatRegister(regNum));
   _floats[regNum - UNW_MIPS_F0] = value;
 #else
+  (void)regNum;
+  (void)value;
   _LIBUNWIND_ABORT("mips_o32 float support not implemented");
 #endif
 }
@@ -3159,6 +3165,8 @@ inline bool Registers_mips_newabi::validFloatRegister(int regNum) const {
 #ifdef __mips_hard_float
   if (regNum >= UNW_MIPS_F0 && regNum <= UNW_MIPS_F31)
     return true;
+#else
+  (void)regNum;
 #endif
   return false;
 }
@@ -3168,6 +3176,7 @@ inline double Registers_mips_newabi::getFloatRegister(int regNum) const {
   assert(validFloatRegister(regNum));
   return _floats[regNum - UNW_MIPS_F0];
 #else
+  (void)regNum;
   _LIBUNWIND_ABORT("mips_newabi float support not implemented");
 #endif
 }
@@ -3178,6 +3187,8 @@ inline void Registers_mips_newabi::setFloatRegister(int regNum,
   assert(validFloatRegister(regNum));
   _floats[regNum - UNW_MIPS_F0] = value;
 #else
+  (void)regNum;
+  (void)value;
   _LIBUNWIND_ABORT("mips_newabi float support not implemented");
 #endif
 }
@@ -3518,6 +3529,187 @@ inline const char *Registers_sparc::getRegisterName(int regNum) {
 }
 #endif // _LIBUNWIND_TARGET_SPARC
 
+#if defined(_LIBUNWIND_TARGET_HEXAGON)
+/// Registers_hexagon holds the register state of a thread in a Hexagon QDSP6
+/// process.
+class _LIBUNWIND_HIDDEN Registers_hexagon {
+public:
+  Registers_hexagon();
+  Registers_hexagon(const void *registers);
+
+  bool        validRegister(int num) const;
+  uint32_t    getRegister(int num) const;
+  void        setRegister(int num, uint32_t value);
+  bool        validFloatRegister(int num) const;
+  double      getFloatRegister(int num) const;
+  void        setFloatRegister(int num, double value);
+  bool        validVectorRegister(int num) const;
+  v128        getVectorRegister(int num) const;
+  void        setVectorRegister(int num, v128 value);
+  const char *getRegisterName(int num);
+  void        jumpto();
+  static int  lastDwarfRegNum() { return _LIBUNWIND_HIGHEST_DWARF_REGISTER_HEXAGON; }
+  static int  getArch() { return REGISTERS_HEXAGON; }
+
+  uint32_t  getSP() const         { return _registers.__r[UNW_HEXAGON_R29]; }
+  void      setSP(uint32_t value) { _registers.__r[UNW_HEXAGON_R29] = value; }
+  uint32_t  getIP() const         { return _registers.__r[UNW_HEXAGON_PC]; }
+  void      setIP(uint32_t value) { _registers.__r[UNW_HEXAGON_PC] = value; }
+
+private:
+  struct hexagon_thread_state_t {
+    unsigned int __r[35];
+  };
+
+  hexagon_thread_state_t _registers;
+};
+
+inline Registers_hexagon::Registers_hexagon(const void *registers) {
+  static_assert((check_fit<Registers_hexagon, unw_context_t>::does_fit),
+                "hexagon registers do not fit into unw_context_t");
+  memcpy(&_registers, static_cast<const uint8_t *>(registers),
+         sizeof(_registers));
+}
+
+inline Registers_hexagon::Registers_hexagon() {
+  memset(&_registers, 0, sizeof(_registers));
+}
+
+inline bool Registers_hexagon::validRegister(int regNum) const {
+  if (regNum <= UNW_HEXAGON_R31)
+    return true;
+  return false;
+}
+
+inline uint32_t Registers_hexagon::getRegister(int regNum) const {
+  if (regNum >= UNW_HEXAGON_R0 && regNum <= UNW_HEXAGON_R31)
+    return _registers.__r[regNum - UNW_HEXAGON_R0];
+
+  switch (regNum) {
+  case UNW_REG_IP:
+    return _registers.__r[UNW_HEXAGON_PC];
+  case UNW_REG_SP:
+    return _registers.__r[UNW_HEXAGON_R29];
+  }
+  _LIBUNWIND_ABORT("unsupported hexagon register");
+}
+
+inline void Registers_hexagon::setRegister(int regNum, uint32_t value) {
+  if (regNum >= UNW_HEXAGON_R0 && regNum <= UNW_HEXAGON_R31) {
+    _registers.__r[regNum - UNW_HEXAGON_R0] = value;
+    return;
+  }
+
+  switch (regNum) {
+  case UNW_REG_IP:
+    _registers.__r[UNW_HEXAGON_PC] = value;
+    return;
+  case UNW_REG_SP:
+    _registers.__r[UNW_HEXAGON_R29] = value;
+    return;
+  }
+  _LIBUNWIND_ABORT("unsupported hexagon register");
+}
+
+inline bool Registers_hexagon::validFloatRegister(int /* regNum */) const {
+  return false;
+}
+
+inline double Registers_hexagon::getFloatRegister(int /* regNum */) const {
+  _LIBUNWIND_ABORT("hexagon float support not implemented");
+}
+
+inline void Registers_hexagon::setFloatRegister(int /* regNum */,
+                                             double /* value */) {
+  _LIBUNWIND_ABORT("hexagon float support not implemented");
+}
+
+inline bool Registers_hexagon::validVectorRegister(int /* regNum */) const {
+  return false;
+}
+
+inline v128 Registers_hexagon::getVectorRegister(int /* regNum */) const {
+  _LIBUNWIND_ABORT("hexagon vector support not implemented");
+}
+
+inline void Registers_hexagon::setVectorRegister(int /* regNum */, v128 /* value */) {
+  _LIBUNWIND_ABORT("hexagon vector support not implemented");
+}
+
+inline const char *Registers_hexagon::getRegisterName(int regNum) {
+  switch (regNum) {
+  case UNW_HEXAGON_R0:
+    return "r0";
+  case UNW_HEXAGON_R1:
+    return "r1";
+  case UNW_HEXAGON_R2:
+    return "r2";
+  case UNW_HEXAGON_R3:
+    return "r3";
+  case UNW_HEXAGON_R4:
+    return "r4";
+  case UNW_HEXAGON_R5:
+    return "r5";
+  case UNW_HEXAGON_R6:
+    return "r6";
+  case UNW_HEXAGON_R7:
+    return "r7";
+  case UNW_HEXAGON_R8:
+    return "r8";
+  case UNW_HEXAGON_R9:
+    return "r9";
+  case UNW_HEXAGON_R10:
+    return "r10";
+  case UNW_HEXAGON_R11:
+    return "r11";
+  case UNW_HEXAGON_R12:
+    return "r12";
+  case UNW_HEXAGON_R13:
+    return "r13";
+  case UNW_HEXAGON_R14:
+    return "r14";
+  case UNW_HEXAGON_R15:
+    return "r15";
+  case UNW_HEXAGON_R16:
+    return "r16";
+  case UNW_HEXAGON_R17:
+    return "r17";
+  case UNW_HEXAGON_R18:
+    return "r18";
+  case UNW_HEXAGON_R19:
+    return "r19";
+  case UNW_HEXAGON_R20:
+    return "r20";
+  case UNW_HEXAGON_R21:
+    return "r21";
+  case UNW_HEXAGON_R22:
+    return "r22";
+  case UNW_HEXAGON_R23:
+    return "r23";
+  case UNW_HEXAGON_R24:
+    return "r24";
+  case UNW_HEXAGON_R25:
+    return "r25";
+  case UNW_HEXAGON_R26:
+    return "r26";
+  case UNW_HEXAGON_R27:
+    return "r27";
+  case UNW_HEXAGON_R28:
+    return "r28";
+  case UNW_HEXAGON_R29:
+    return "r29";
+  case UNW_HEXAGON_R30:
+    return "r30";
+  case UNW_HEXAGON_R31:
+    return "r31";
+  default:
+    return "unknown register";
+  }
+
+}
+#endif // _LIBUNWIND_TARGET_HEXAGON
+
+
 #if defined(_LIBUNWIND_TARGET_RISCV)
 /// Registers_riscv holds the register state of a thread in a 64-bit RISC-V
 /// process.
@@ -3542,11 +3734,11 @@ public:
 
   uint64_t  getSP() const         { return _registers[2]; }
   void      setSP(uint64_t value) { _registers[2] = value; }
-  uint64_t  getIP() const         { return _registers[1]; }
-  void      setIP(uint64_t value) { _registers[1] = value; }
+  uint64_t  getIP() const         { return _registers[0]; }
+  void      setIP(uint64_t value) { _registers[0] = value; }
 
 private:
-
+  // _registers[0] holds the pc
   uint64_t _registers[32];
   double   _floats[32];
 };
@@ -3581,7 +3773,7 @@ inline bool Registers_riscv::validRegister(int regNum) const {
 
 inline uint64_t Registers_riscv::getRegister(int regNum) const {
   if (regNum == UNW_REG_IP)
-    return _registers[1];
+    return _registers[0];
   if (regNum == UNW_REG_SP)
     return _registers[2];
   if (regNum == UNW_RISCV_X0)
@@ -3593,7 +3785,7 @@ inline uint64_t Registers_riscv::getRegister(int regNum) const {
 
 inline void Registers_riscv::setRegister(int regNum, uint64_t value) {
   if (regNum == UNW_REG_IP)
-    _registers[1] = value;
+    _registers[0] = value;
   else if (regNum == UNW_REG_SP)
     _registers[2] = value;
   else if (regNum == UNW_RISCV_X0)
@@ -3757,6 +3949,7 @@ inline double Registers_riscv::getFloatRegister(int regNum) const {
   assert(validFloatRegister(regNum));
   return _floats[regNum - UNW_RISCV_F0];
 #else
+  (void)regNum;
   _LIBUNWIND_ABORT("libunwind not built with float support");
 #endif
 }
@@ -3766,6 +3959,8 @@ inline void Registers_riscv::setFloatRegister(int regNum, double value) {
   assert(validFloatRegister(regNum));
   _floats[regNum - UNW_RISCV_F0] = value;
 #else
+  (void)regNum;
+  (void)value;
   _LIBUNWIND_ABORT("libunwind not built with float support");
 #endif
 }
diff --git a/libunwind/src/Unwind-EHABI.cpp b/libunwind/src/Unwind-EHABI.cpp
index a23ba2cc7e0e..32b5cbc3be92 100644
--- a/libunwind/src/Unwind-EHABI.cpp
+++ b/libunwind/src/Unwind-EHABI.cpp
@@ -31,10 +31,12 @@ namespace {
 // signinficant byte.
 uint8_t getByte(const uint32_t* data, size_t offset) {
   const uint8_t* byteData = reinterpret_cast<const uint8_t*>(data);
-#ifdef __LITTLE_ENDIAN__
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
   return byteData[(offset & ~(size_t)0x03) + (3 - (offset & (size_t)0x03))];
-#else
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
   return byteData[offset];
+#else
+#error "Unable to determine endianess"
 #endif
 }
 
@@ -481,8 +483,8 @@ unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
     // 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);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(long)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase1(ex_ojb=%p): calling personality function %p",
           static_cast<void *>(exception_object),
@@ -597,8 +599,8 @@ static _Unwind_Reason_Code unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(long)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(long)(frameInfo.handler);
       struct _Unwind_Context *context = (struct _Unwind_Context *)(cursor);
       // EHABI #7.2
       exception_object->pr_cache.fnstart = frameInfo.start_ip;
@@ -943,10 +945,12 @@ _Unwind_VRS_Pop(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
         // SP is only 32-bit aligned so don't copy 64-bit at a time.
         uint64_t w0 = *sp++;
         uint64_t w1 = *sp++;
-#ifdef __LITTLE_ENDIAN__
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
         uint64_t value = (w1 << 32) | w0;
-#else
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
         uint64_t value = (w0 << 32) | w1;
+#else
+#error "Unable to determine endianess"
 #endif
         if (_Unwind_VRS_Set(context, regclass, i, representation, &value) !=
             _UVRSR_OK)
diff --git a/libunwind/src/Unwind-seh.cpp b/libunwind/src/Unwind-seh.cpp
index 7647f2e0db0b..403ab2d77110 100644
--- a/libunwind/src/Unwind-seh.cpp
+++ b/libunwind/src/Unwind-seh.cpp
@@ -69,7 +69,7 @@ static void __unw_seh_set_disp_ctx(unw_cursor_t *cursor,
 ///  b) Initiate a collided unwind to halt unwinding.
 _LIBUNWIND_EXPORT EXCEPTION_DISPOSITION
 _GCC_specific_handler(PEXCEPTION_RECORD ms_exc, PVOID frame, PCONTEXT ms_ctx,
-                      DISPATCHER_CONTEXT *disp, __personality_routine pers) {
+                      DISPATCHER_CONTEXT *disp, _Unwind_Personality_Fn pers) {
   unw_cursor_t cursor;
   _Unwind_Exception *exc;
   _Unwind_Action action;
@@ -290,8 +290,8 @@ unwind_phase2_forced(unw_context_t *uc,
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(intptr_t)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(intptr_t)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase2_forced(ex_ojb=%p): calling personality function %p",
           (void *)exception_object, (void *)(uintptr_t)p);
diff --git a/libunwind/src/Unwind-sjlj.c b/libunwind/src/Unwind-sjlj.c
index b8bb7c83bdff..85a4cc3c69d6 100644
--- a/libunwind/src/Unwind-sjlj.c
+++ b/libunwind/src/Unwind-sjlj.c
@@ -39,7 +39,7 @@ struct _Unwind_FunctionContext {
   uint32_t                        resumeParameters[4];
 
   // set by calling function before registering
-  __personality_routine           personality; // arm offset=24
+  _Unwind_Personality_Fn personality;          // arm offset=24
   uintptr_t                       lsda;        // arm offset=28
 
   // variable length array, contains registers to restore
@@ -268,7 +268,7 @@ unwind_phase2_forced(struct _Unwind_Exception *exception_object,
 
     // if there is a personality routine, tell it we are unwinding
     if (c->personality != NULL) {
-      __personality_routine p = (__personality_routine) c->personality;
+      _Unwind_Personality_Fn p = (_Unwind_Personality_Fn)c->personality;
       _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
                                  "calling personality function %p",
                                  (void *)exception_object, (void *)p);
diff --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp
index 31be8366d238..f346c720d22c 100644
--- a/libunwind/src/UnwindCursor.hpp
+++ b/libunwind/src/UnwindCursor.hpp
@@ -1123,6 +1123,12 @@ private:
   }
 #endif
 
+#if defined (_LIBUNWIND_TARGET_HEXAGON)
+  compact_unwind_encoding_t dwarfEncoding(Registers_hexagon &) const {
+    return 0;
+  }
+#endif
+
 #if defined (_LIBUNWIND_TARGET_MIPS_O32)
   compact_unwind_encoding_t dwarfEncoding(Registers_mips_o32 &) const {
     return 0;
@@ -1269,7 +1275,7 @@ struct EHABISectionIterator {
   _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; }
+  size_t operator-(const _Self& other) const { return _i - other._i; }
 
   bool operator==(const _Self& other) const {
     assert(_addressSpace == other._addressSpace);
@@ -1277,6 +1283,12 @@ struct EHABISectionIterator {
     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 {
@@ -1353,7 +1365,8 @@ bool UnwindCursor<A, R>::getInfoFromEHABISection(
 
   // 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).
+  // the table points at an offset in the exception handling table (section 5
+  // EHABI).
   pint_t exceptionTableAddr;
   uint32_t exceptionTableData;
   bool isSingleWordEHT;
@@ -1452,7 +1465,7 @@ bool UnwindCursor<A, R>::getInfoFromEHABISection(
   _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?
+  _info.flags = (isSingleWordEHT ? 1 : 0) | (scope32 ? 0x2 : 0);  // Use enum?
 
   return true;
 }
@@ -1847,6 +1860,12 @@ void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {
   pc &= (pint_t)~0x1;
 #endif
 
+  // Exit early if at the top of the stack.
+  if (pc == 0) {
+    _unwindInfoMissing = true;
+    return;
+  }
+
   // If the last line of a function is a "throw" the compiler sometimes
   // emits no instructions after the call to __cxa_throw.  This means
   // the return address is actually the start of the next function.
diff --git a/libunwind/src/UnwindLevel1-gcc-ext.c b/libunwind/src/UnwindLevel1-gcc-ext.c
index 008df815665e..310b836d129e 100644
--- a/libunwind/src/UnwindLevel1-gcc-ext.c
+++ b/libunwind/src/UnwindLevel1-gcc-ext.c
@@ -149,7 +149,7 @@ _Unwind_Backtrace(_Unwind_Trace_Fn callback, void *ref) {
 
     struct _Unwind_Context *context = (struct _Unwind_Context *)&cursor;
     // Get and call the personality function to unwind the frame.
-    __personality_routine handler = (__personality_routine) frameInfo.handler;
+    _Unwind_Personality_Fn handler = (_Unwind_Personality_Fn)frameInfo.handler;
     if (handler == NULL) {
       return _URC_END_OF_STACK;
     }
diff --git a/libunwind/src/UnwindLevel1.c b/libunwind/src/UnwindLevel1.c
index bcb1a7fbec2a..3e75b5f13cd6 100644
--- a/libunwind/src/UnwindLevel1.c
+++ b/libunwind/src/UnwindLevel1.c
@@ -90,8 +90,8 @@ unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
     // 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)(uintptr_t)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(uintptr_t)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase1(ex_ojb=%p): calling personality function %p",
           (void *)exception_object, (void *)(uintptr_t)p);
@@ -188,8 +188,8 @@ unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(uintptr_t)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(uintptr_t)(frameInfo.handler);
       _Unwind_Action action = _UA_CLEANUP_PHASE;
       if (sp == exception_object->private_2) {
         // Tell personality this was the frame it marked in phase 1.
@@ -294,8 +294,8 @@ unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor,
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(intptr_t)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(intptr_t)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase2_forced(ex_ojb=%p): calling personality function %p",
           (void *)exception_object, (void *)(uintptr_t)p);
diff --git a/libunwind/src/UnwindRegistersRestore.S b/libunwind/src/UnwindRegistersRestore.S
index cbb2fd447005..5d5443215286 100644
--- a/libunwind/src/UnwindRegistersRestore.S
+++ b/libunwind/src/UnwindRegistersRestore.S
@@ -557,7 +557,7 @@ Lnovec:
   lwz     %r3,  20(%r3)   // do r3 last
   bctr
 
-#elif defined(__arm64__) || defined(__aarch64__)
+#elif defined(__aarch64__)
 
 //
 // void libunwind::Registers_arm64::jumpto()
@@ -808,6 +808,48 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind14Registers_or1k6jumptoEv)
   l.jr     r9
    l.nop
 
+#elif defined(__hexagon__)
+# On entry:
+#  thread_state pointer is in r2
+DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind17Registers_hexagon6jumptoEv)
+#
+# void libunwind::Registers_hexagon::jumpto()
+#
+  r8 = memw(r0+#32)
+  r9 = memw(r0+#36)
+  r10 = memw(r0+#40)
+  r11 = memw(r0+#44)
+
+  r12 = memw(r0+#48)
+  r13 = memw(r0+#52)
+  r14 = memw(r0+#56)
+  r15 = memw(r0+#60)
+
+  r16 = memw(r0+#64)
+  r17 = memw(r0+#68)
+  r18 = memw(r0+#72)
+  r19 = memw(r0+#76)
+
+  r20 = memw(r0+#80)
+  r21 = memw(r0+#84)
+  r22 = memw(r0+#88)
+  r23 = memw(r0+#92)
+
+  r24 = memw(r0+#96)
+  r25 = memw(r0+#100)
+  r26 = memw(r0+#104)
+  r27 = memw(r0+#108)
+
+  r28 = memw(r0+#112)
+  r29 = memw(r0+#116)
+  r30 = memw(r0+#120)
+  r31 = memw(r0+#132)
+
+  r1 = memw(r0+#128)
+  c4 = r1   // Predicate register
+  r1 = memw(r0+#4)
+  r0 = memw(r0)
+  jumpr r31
 #elif defined(__mips__) && defined(_ABIO32) && _MIPS_SIM == _ABIO32
 
 //
@@ -1075,7 +1117,7 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind15Registers_riscv6jumptoEv)
 #endif
 
   // x0 is zero
-  ld    x1, (8 * 1)(a0)
+  ld    x1, (8 * 0)(a0) // restore pc into ra
   ld    x2, (8 * 2)(a0)
   ld    x3, (8 * 3)(a0)
   ld    x4, (8 * 4)(a0)
diff --git a/libunwind/src/UnwindRegistersSave.S b/libunwind/src/UnwindRegistersSave.S
index da91abc233de..51bb9b0688fd 100644
--- a/libunwind/src/UnwindRegistersSave.S
+++ b/libunwind/src/UnwindRegistersSave.S
@@ -697,7 +697,7 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
   blr
 
 
-#elif defined(__arm64__) || defined(__aarch64__)
+#elif defined(__aarch64__)
 
 //
 // extern int __unw_getcontext(unw_context_t* thread_state)
@@ -945,6 +945,52 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
   # zero epcr
   l.sw     132(r3), r0
 
+#elif defined(__hexagon__)
+#
+# extern int unw_getcontext(unw_context_t* thread_state)
+#
+# On entry:
+#  thread_state pointer is in r0
+#
+#define OFFSET(offset) (offset/4)
+DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
+  memw(r0+#32) = r8
+  memw(r0+#36) = r9
+  memw(r0+#40) = r10
+  memw(r0+#44) = r11
+
+  memw(r0+#48) = r12
+  memw(r0+#52) = r13
+  memw(r0+#56) = r14
+  memw(r0+#60) = r15
+
+  memw(r0+#64) = r16
+  memw(r0+#68) = r17
+  memw(r0+#72) = r18
+  memw(r0+#76) = r19
+
+  memw(r0+#80) = r20
+  memw(r0+#84) = r21
+  memw(r0+#88) = r22
+  memw(r0+#92) = r23
+
+  memw(r0+#96) = r24
+  memw(r0+#100) = r25
+  memw(r0+#104) = r26
+  memw(r0+#108) = r27
+
+  memw(r0+#112) = r28
+  memw(r0+#116) = r29
+  memw(r0+#120) = r30
+  memw(r0+#124) = r31
+  r1 = c4   // Predicate register
+  memw(r0+#128) = r1
+  r1 = memw(r30)           // *FP == Saved FP
+  r1 = r31
+  memw(r0+#132) = r1
+
+  jumpr r31
+
 #elif defined(__sparc__)
 
 #
@@ -984,7 +1030,7 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
 #  thread_state pointer is in a0
 #
 DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
-  // x0 is zero
+  sd    x1, (8 * 0)(a0) // store ra as pc
   sd    x1, (8 * 1)(a0)
   sd    x2, (8 * 2)(a0)
   sd    x3, (8 * 3)(a0)
diff --git a/libunwind/src/Unwind_AppleExtras.cpp b/libunwind/src/Unwind_AppleExtras.cpp
index 248d99570e94..536303993eff 100644
--- a/libunwind/src/Unwind_AppleExtras.cpp
+++ b/libunwind/src/Unwind_AppleExtras.cpp
@@ -56,7 +56,7 @@ struct libgcc_object_info {
           __attribute__((visibility("default"))) const char sym##_tmp42 = 0; \
        extern const char sym##_tmp43 __asm("$ld$hide$os4.3$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp43 = 0;
-#elif defined(__arm64__)
+#elif defined(__aarch64__)
   #define NOT_HERE_BEFORE_10_6(sym)
   #define NEVER_HERE(sym)
 #else
diff --git a/libunwind/src/assembly.h b/libunwind/src/assembly.h
index 7132b6c561b0..4cf179e13edc 100644
--- a/libunwind/src/assembly.h
+++ b/libunwind/src/assembly.h
@@ -28,7 +28,7 @@
 #ifdef _ARCH_PWR8
 #define PPC64_HAS_VMX
 #endif
-#elif defined(__arm64__)
+#elif defined(__APPLE__) && defined(__aarch64__)
 #define SEPARATOR %%
 #else
 #define SEPARATOR ;
@@ -75,9 +75,16 @@
 #define EXPORT_SYMBOL(name)
 #define HIDDEN_SYMBOL(name) .hidden name
 #define WEAK_SYMBOL(name) .weak name
+
+#if defined(__hexagon__)
+#define WEAK_ALIAS(name, aliasname) \
+  WEAK_SYMBOL(aliasname) SEPARATOR                                             \
+  .equiv SYMBOL_NAME(aliasname), SYMBOL_NAME(name)
+#else
 #define WEAK_ALIAS(name, aliasname)                                            \
   WEAK_SYMBOL(aliasname) SEPARATOR                                             \
   SYMBOL_NAME(aliasname) = SYMBOL_NAME(name)
+#endif
 
 #if defined(__GNU__) || defined(__FreeBSD__) || defined(__Fuchsia__) || \
     defined(__linux__)
diff --git a/libunwind/src/config.h b/libunwind/src/config.h
index dcd3cef94552..842fd829af19 100644
--- a/libunwind/src/config.h
+++ b/libunwind/src/config.h
@@ -102,9 +102,10 @@
 #if defined(__i386__) || defined(__x86_64__) ||                                \
     defined(__ppc__) || defined(__ppc64__) || defined(__powerpc64__) ||        \
     (!defined(__APPLE__) && defined(__arm__)) ||                               \
-    (defined(__arm64__) || defined(__aarch64__)) ||                            \
+    defined(__aarch64__) ||                                                    \
     defined(__mips__) ||                                                       \
-    defined(__riscv)
+    defined(__riscv) ||                                                        \
+    defined(__hexagon__)
 #if !defined(_LIBUNWIND_BUILD_SJLJ_APIS)
 #define _LIBUNWIND_BUILD_ZERO_COST_APIS
 #endif
@@ -122,8 +123,7 @@
 #else
 #define _LIBUNWIND_ABORT(msg)                                                  \
   do {                                                                         \
-    fprintf(stderr, "libunwind: %s %s:%d - %s\n", __func__, __FILE__,          \
-            __LINE__, msg);                                                    \
+    fprintf(stderr, "libunwind: %s - %s\n", __func__, msg);                    \
     fflush(stderr);                                                            \
     abort();                                                                   \
   } while (0)
diff --git a/libunwind/src/libunwind.cpp b/libunwind/src/libunwind.cpp
index 1ee58ad1971e..fd079da30895 100644
--- a/libunwind/src/libunwind.cpp
+++ b/libunwind/src/libunwind.cpp
@@ -50,6 +50,8 @@ _LIBUNWIND_HIDDEN int __unw_init_local(unw_cursor_t *cursor,
 # define REGISTER_KIND Registers_arm
 #elif defined(__or1k__)
 # define REGISTER_KIND Registers_or1k
+#elif defined(__hexagon__)
+# define REGISTER_KIND Registers_hexagon
 #elif defined(__mips__) && defined(_ABIO32) && _MIPS_SIM == _ABIO32
 # define REGISTER_KIND Registers_mips_o32
 #elif defined(__mips64)