3 files changed, 60 insertions, 2 deletions
diff --git a/absl/debugging/internal/examine_stack.cc b/absl/debugging/internal/examine_stack.cc
index a3dd893a9dfe..6e5ff1fbd836 100644
--- a/absl/debugging/internal/examine_stack.cc
+++ b/absl/debugging/internal/examine_stack.cc
@@ -20,6 +20,10 @@
 #include <unistd.h>
 #endif
 
+#ifdef __APPLE__
+#include <sys/ucontext.h>
+#endif
+
 #include <csignal>
 #include <cstdio>
 
@@ -66,6 +70,32 @@ void* GetProgramCounter(void* vuc) {
 #error "Undefined Architecture."
 #endif
   }
+#elif defined(__APPLE__)
+  if (vuc != nullptr) {
+    ucontext_t* signal_ucontext = reinterpret_cast<ucontext_t*>(vuc);
+#if defined(__aarch64__)
+    return reinterpret_cast<void*>(
+        __darwin_arm_thread_state64_get_pc(signal_ucontext->uc_mcontext->__ss));
+#elif defined(__arm__)
+#if __DARWIN_UNIX03
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__pc);
+#else
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.pc);
+#endif
+#elif defined(__i386__)
+#if __DARWIN_UNIX03
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__eip);
+#else
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.eip);
+#endif
+#elif defined(__x86_64__)
+#if __DARWIN_UNIX03
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__rip);
+#else
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.rip);
+#endif
+#endif
+  }
 #elif defined(__akaros__)
   auto* ctx = reinterpret_cast<struct user_context*>(vuc);
   return reinterpret_cast<void*>(get_user_ctx_pc(ctx));
diff --git a/absl/debugging/internal/stacktrace_config.h b/absl/debugging/internal/stacktrace_config.h
index d4e8480a8e28..d5cc17401396 100644
--- a/absl/debugging/internal/stacktrace_config.h
+++ b/absl/debugging/internal/stacktrace_config.h
@@ -28,6 +28,27 @@
 #define ABSL_STACKTRACE_INL_HEADER \
     "absl/debugging/internal/stacktrace_win32-inl.inc"
 
+#elif defined(__APPLE__)
+// Thread local support required for UnwindImpl.
+// Notes:
+// * Xcode's clang did not support `thread_local` until version 8, and
+//   even then not for all iOS < 9.0.
+// * Xcode 9.3 started disallowing `thread_local` for 32-bit iOS simulator
+//   targeting iOS 9.x.
+// * Xcode 10 moves the deployment target check for iOS < 9.0 to link time
+//   making __has_feature unreliable there.
+//
+// Otherwise, `__has_feature` is only supported by Clang so it has be inside
+// `defined(__APPLE__)` check.
+#if __has_feature(cxx_thread_local) && \
+    !(TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)
+#define ABSL_STACKTRACE_INL_HEADER \
+  "absl/debugging/internal/stacktrace_generic-inl.inc"
+#else
+#define ABSL_STACKTRACE_INL_HEADER \
+  "absl/debugging/internal/stacktrace_unimplemented-inl.inc"
+#endif
+
 #elif defined(__linux__) && !defined(__ANDROID__)
 
 #if !defined(NO_FRAME_POINTER)
@@ -40,7 +61,7 @@
 # elif defined(__aarch64__)
 #define ABSL_STACKTRACE_INL_HEADER \
     "absl/debugging/internal/stacktrace_aarch64-inl.inc"
-# elif defined(__arm__)
+#elif defined(__arm__) && defined(__GLIBC__)
 // Note: When using glibc this may require -funwind-tables to function properly.
 #define ABSL_STACKTRACE_INL_HEADER \
   "absl/debugging/internal/stacktrace_generic-inl.inc"
diff --git a/absl/debugging/internal/symbolize.h b/absl/debugging/internal/symbolize.h
index 5d0858b5c7e1..663d774d42fa 100644
--- a/absl/debugging/internal/symbolize.h
+++ b/absl/debugging/internal/symbolize.h
@@ -22,6 +22,7 @@
 #include <cstdint>
 
 #include "absl/base/config.h"
+#include "absl/strings/string_view.h"
 
 #ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
 #error ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE cannot be directly set
@@ -45,7 +46,7 @@ namespace debugging_internal {
 //
 // This is not async-signal-safe.
 bool ForEachSection(int fd,
-                    const std::function<bool(const std::string& name,
+                    const std::function<bool(absl::string_view name,
                                              const ElfW(Shdr) &)>& callback);
 
 // Gets the section header for the given name, if it exists. Returns true on
@@ -59,6 +60,12 @@ ABSL_NAMESPACE_END
 
 #endif  // ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
 
+#ifdef ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE
+#error ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE cannot be directly set
+#elif defined(__APPLE__)
+#define ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE 1
+#endif
+
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {