One more change required to build the sanitizers for iOS.

[beanz]

Summary

_Unwind_Backtrace is not available on iOS, so we should ifdef out the posix implementations of BufferedStackTrace::SlowUnwindStack and BufferedStackTrace::SlowUnwindStackWithContext on iOS.

[samsonov]

All this looks weird to me.

1. Slow unwind is not available on Mac at all (see SANITIZER_CAN_SLOW_UNWIND macro).
2. You #ifdef out BufferedStackTrace methods which are referenced from other files (sanitizer_stacktrace_libcdep.cc)
3. You don't #ifdef out another _Unwind-related helper methods like Unwind_Trace, Unwind_GetIP, which are only used in functions you #ifdef out.

Looks like this whole *file* makes no sense on Mac, as we're not using slow unwinder there. I'd suggest we just rename it to smth. like sanitizer_unwind_linux_libcdep.cc, and use it on Linux/Android/FreeBSD only.

[beanz]

Updating based on feedback from samsonov.

Renaming file from posix->linux and changing the #ifdef guard.

[samsonov]

LGTM. Please make sure that it doesn't break the build on OS X, not only fixes iOS.

lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cc

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(On Diff #28374)

Update file name.

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(On Diff #28374)

Update comment here.

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(On Diff #28374)

Update comment here.

compiler-rt/trunk/lib/sanitizer_common/CMakeLists.txt

set(SANITIZER_LIBCDEP_SOURCES
   sanitizer_coverage_mapping_libcdep.cc
   sanitizer_linux_libcdep.cc
   sanitizer_posix_libcdep.cc
   sanitizer_stacktrace_libcdep.cc
   sanitizer_stoptheworld_linux_libcdep.cc
   sanitizer_symbolizer_libcdep.cc
   sanitizer_symbolizer_posix_libcdep.cc
   sanitizer_symbolizer_process_libcdep.cc
-  sanitizer_unwind_posix_libcdep.cc)
+  sanitizer_unwind_linux_libcdep.cc)
 
 # Explicitly list all sanitizer_common headers. Not all of these are
 # included in sanitizer_common source files, but we need to depend on
 # headers when building our custom unit tests.
 set(SANITIZER_HEADERS
   sanitizer_addrhashmap.h
   sanitizer_allocator.h
   sanitizer_allocator_interface.h

compiler-rt/trunk/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cc

+//===-- sanitizer_unwind_linux_libcdep.cc ---------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the unwind.h-based (aka "slow") stack unwinding routines
+// available to the tools on Linux, Android, and FreeBSD.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_FREEBSD || SANITIZER_LINUX
+#include "sanitizer_common.h"
+#include "sanitizer_stacktrace.h"
+
+#if SANITIZER_ANDROID
+#include <dlfcn.h>  // for dlopen()
+#endif
+
+#if SANITIZER_FREEBSD
+#define _GNU_SOURCE  // to declare _Unwind_Backtrace() from <unwind.h>
+#endif
+#include <unwind.h>
+
+namespace __sanitizer {
+
+//------------------------- SlowUnwindStack -----------------------------------
+
+typedef struct {
+  uptr absolute_pc;
+  uptr stack_top;
+  uptr stack_size;
+} backtrace_frame_t;
+
+extern "C" {
+typedef void *(*acquire_my_map_info_list_func)();
+typedef void (*release_my_map_info_list_func)(void *map);
+typedef sptr (*unwind_backtrace_signal_arch_func)(
+    void *siginfo, void *sigcontext, void *map_info_list,
+    backtrace_frame_t *backtrace, uptr ignore_depth, uptr max_depth);
+acquire_my_map_info_list_func acquire_my_map_info_list;
+release_my_map_info_list_func release_my_map_info_list;
+unwind_backtrace_signal_arch_func unwind_backtrace_signal_arch;
+} // extern "C"
+
+#if SANITIZER_ANDROID
+void SanitizerInitializeUnwinder() {
+  void *p = dlopen("libcorkscrew.so", RTLD_LAZY);
+  if (!p) {
+    VReport(1,
+            "Failed to open libcorkscrew.so. You may see broken stack traces "
+            "in SEGV reports.");
+    return;
+  }
+  acquire_my_map_info_list =
+      (acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list");
+  release_my_map_info_list =
+      (release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list");
+  unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym(
+      p, "unwind_backtrace_signal_arch");
+  if (!acquire_my_map_info_list || !release_my_map_info_list ||
+      !unwind_backtrace_signal_arch) {
+    VReport(1,
+            "Failed to find one of the required symbols in libcorkscrew.so. "
+            "You may see broken stack traces in SEGV reports.");
+    acquire_my_map_info_list = 0;
+    unwind_backtrace_signal_arch = 0;
+    release_my_map_info_list = 0;
+  }
+}
+#endif
+
+#ifdef __arm__
+#define UNWIND_STOP _URC_END_OF_STACK
+#define UNWIND_CONTINUE _URC_NO_REASON
+#else
+#define UNWIND_STOP _URC_NORMAL_STOP
+#define UNWIND_CONTINUE _URC_NO_REASON
+#endif
+
+uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
+#if defined(__arm__) && !SANITIZER_MAC
+  uptr val;
+  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
+      15 /* r15 = PC */, _UVRSD_UINT32, &val);
+  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
+  // Clear the Thumb bit.
+  return val & ~(uptr)1;
+#else
+  return _Unwind_GetIP(ctx);
+#endif
+}
+
+struct UnwindTraceArg {
+  BufferedStackTrace *stack;
+  u32 max_depth;
+};
+
+_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
+  UnwindTraceArg *arg = (UnwindTraceArg*)param;
+  CHECK_LT(arg->stack->size, arg->max_depth);
+  uptr pc = Unwind_GetIP(ctx);
+  arg->stack->trace_buffer[arg->stack->size++] = pc;
+  if (arg->stack->size == arg->max_depth) return UNWIND_STOP;
+  return UNWIND_CONTINUE;
+}
+
+void BufferedStackTrace::SlowUnwindStack(uptr pc, u32 max_depth) {
+  CHECK_GE(max_depth, 2);
+  size = 0;
+  UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
+  _Unwind_Backtrace(Unwind_Trace, &arg);
+  // We need to pop a few frames so that pc is on top.
+  uptr to_pop = LocatePcInTrace(pc);
+  // trace_buffer[0] belongs to the current function so we always pop it,
+  // unless there is only 1 frame in the stack trace (1 frame is always better
+  // than 0!).
+  // 1-frame stacks don't normally happen, but this depends on the actual
+  // unwinder implementation (libgcc, libunwind, etc) which is outside of our
+  // control.
+  if (to_pop == 0 && size > 1)
+    to_pop = 1;
+  PopStackFrames(to_pop);
+  trace_buffer[0] = pc;
+}
+
+void BufferedStackTrace::SlowUnwindStackWithContext(uptr pc, void *context,
+                                                    u32 max_depth) {
+  CHECK_GE(max_depth, 2);
+  if (!unwind_backtrace_signal_arch) {
+    SlowUnwindStack(pc, max_depth);
+    return;
+  }
+
+  void *map = acquire_my_map_info_list();
+  CHECK(map);
+  InternalScopedBuffer<backtrace_frame_t> frames(kStackTraceMax);
+  // siginfo argument appears to be unused.
+  sptr res = unwind_backtrace_signal_arch(/* siginfo */ 0, context, map,
+                                          frames.data(),
+                                          /* ignore_depth */ 0, max_depth);
+  release_my_map_info_list(map);
+  if (res < 0) return;
+  CHECK_LE((uptr)res, kStackTraceMax);
+
+  size = 0;
+  // +2 compensate for libcorkscrew unwinder returning addresses of call
+  // instructions instead of raw return addresses.
+  for (sptr i = 0; i < res; ++i)
+    trace_buffer[size++] = frames[i].absolute_pc + 2;
+}
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_FREEBSD || SANITIZER_LINUX

compiler-rt/trunk/lib/sanitizer_common/sanitizer_unwind_posix_libcdep.cc

-//===-- sanitizer_unwind_posix.cc ----------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file contains the unwind.h-based (aka "slow") stack unwinding routines
-// available to the tools on Linux, Android, FreeBSD and OS X.
-//===----------------------------------------------------------------------===//
-
-#include "sanitizer_platform.h"
-#if SANITIZER_POSIX
-#include "sanitizer_common.h"
-#include "sanitizer_stacktrace.h"
-
-#if SANITIZER_ANDROID
-#include <dlfcn.h>  // for dlopen()
-#endif
-
-#if SANITIZER_FREEBSD
-#define _GNU_SOURCE  // to declare _Unwind_Backtrace() from <unwind.h>
-#endif
-#include <unwind.h>
-
-namespace __sanitizer {
-
-//------------------------- SlowUnwindStack -----------------------------------
-
-typedef struct {
-  uptr absolute_pc;
-  uptr stack_top;
-  uptr stack_size;
-} backtrace_frame_t;
-
-extern "C" {
-typedef void *(*acquire_my_map_info_list_func)();
-typedef void (*release_my_map_info_list_func)(void *map);
-typedef sptr (*unwind_backtrace_signal_arch_func)(
-    void *siginfo, void *sigcontext, void *map_info_list,
-    backtrace_frame_t *backtrace, uptr ignore_depth, uptr max_depth);
-acquire_my_map_info_list_func acquire_my_map_info_list;
-release_my_map_info_list_func release_my_map_info_list;
-unwind_backtrace_signal_arch_func unwind_backtrace_signal_arch;
-} // extern "C"
-
-#if SANITIZER_ANDROID
-void SanitizerInitializeUnwinder() {
-  void *p = dlopen("libcorkscrew.so", RTLD_LAZY);
-  if (!p) {
-    VReport(1,
-            "Failed to open libcorkscrew.so. You may see broken stack traces "
-            "in SEGV reports.");
-    return;
-  }
-  acquire_my_map_info_list =
-      (acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list");
-  release_my_map_info_list =
-      (release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list");
-  unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym(
-      p, "unwind_backtrace_signal_arch");
-  if (!acquire_my_map_info_list || !release_my_map_info_list ||
-      !unwind_backtrace_signal_arch) {
-    VReport(1,
-            "Failed to find one of the required symbols in libcorkscrew.so. "
-            "You may see broken stack traces in SEGV reports.");
-    acquire_my_map_info_list = 0;
-    unwind_backtrace_signal_arch = 0;
-    release_my_map_info_list = 0;
-  }
-}
-#endif
-
-#ifdef __arm__
-#define UNWIND_STOP _URC_END_OF_STACK
-#define UNWIND_CONTINUE _URC_NO_REASON
-#else
-#define UNWIND_STOP _URC_NORMAL_STOP
-#define UNWIND_CONTINUE _URC_NO_REASON
-#endif
-
-uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
-#if defined(__arm__) && !SANITIZER_MAC
-  uptr val;
-  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
-      15 /* r15 = PC */, _UVRSD_UINT32, &val);
-  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
-  // Clear the Thumb bit.
-  return val & ~(uptr)1;
-#else
-  return _Unwind_GetIP(ctx);
-#endif
-}
-
-struct UnwindTraceArg {
-  BufferedStackTrace *stack;
-  u32 max_depth;
-};
-
-_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
-  UnwindTraceArg *arg = (UnwindTraceArg*)param;
-  CHECK_LT(arg->stack->size, arg->max_depth);
-  uptr pc = Unwind_GetIP(ctx);
-  arg->stack->trace_buffer[arg->stack->size++] = pc;
-  if (arg->stack->size == arg->max_depth) return UNWIND_STOP;
-  return UNWIND_CONTINUE;
-}
-
-void BufferedStackTrace::SlowUnwindStack(uptr pc, u32 max_depth) {
-  CHECK_GE(max_depth, 2);
-  size = 0;
-  UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
-  _Unwind_Backtrace(Unwind_Trace, &arg);
-  // We need to pop a few frames so that pc is on top.
-  uptr to_pop = LocatePcInTrace(pc);
-  // trace_buffer[0] belongs to the current function so we always pop it,
-  // unless there is only 1 frame in the stack trace (1 frame is always better
-  // than 0!).
-  // 1-frame stacks don't normally happen, but this depends on the actual
-  // unwinder implementation (libgcc, libunwind, etc) which is outside of our
-  // control.
-  if (to_pop == 0 && size > 1)
-    to_pop = 1;
-  PopStackFrames(to_pop);
-  trace_buffer[0] = pc;
-}
-
-void BufferedStackTrace::SlowUnwindStackWithContext(uptr pc, void *context,
-                                                    u32 max_depth) {
-  CHECK_GE(max_depth, 2);
-  if (!unwind_backtrace_signal_arch) {
-    SlowUnwindStack(pc, max_depth);
-    return;
-  }
-
-  void *map = acquire_my_map_info_list();
-  CHECK(map);
-  InternalScopedBuffer<backtrace_frame_t> frames(kStackTraceMax);
-  // siginfo argument appears to be unused.
-  sptr res = unwind_backtrace_signal_arch(/* siginfo */ 0, context, map,
-                                          frames.data(),
-                                          /* ignore_depth */ 0, max_depth);
-  release_my_map_info_list(map);
-  if (res < 0) return;
-  CHECK_LE((uptr)res, kStackTraceMax);
-
-  size = 0;
-  // +2 compensate for libcorkscrew unwinder returning addresses of call
-  // instructions instead of raw return addresses.
-  for (sptr i = 0; i < res; ++i)
-    trace_buffer[size++] = frames[i].absolute_pc + 2;
-}
-
-}  // namespace __sanitizer
-
-#endif  // SANITIZER_POSIX