[Backtracing] Add an indication that we're working on a backtrace.

When we crash, emit a message straight away that says we're working
on a backtrace.  If starting the backtracer fails, report that also.

Finally, add a duration to the messages output by the backtracer, so
that we can see how long it took.

rdar://118055527

include/swift/Runtime/Backtrace.h

@@ -31,114 +31,17 @@
 
 #include <inttypes.h>
 
-#ifdef _WIN32
-// For DWORD
-#define WIN32_LEAN_AND_MEAN
-#define NOMINMAX
-#include <windows.h>
-
-// For wchar_t
-#include <cwchar>
-#endif
-
 #ifdef __cplusplus
 namespace swift {
 namespace runtime {
 namespace backtrace {
 #endif
 
-#ifdef _WIN32
-typedef wchar_t ArgChar;
-typedef DWORD ErrorCode;
-#else
-typedef char ArgChar;
-typedef int ErrorCode;
-#endif
-
-SWIFT_RUNTIME_STDLIB_INTERNAL ErrorCode _swift_installCrashHandler();
-
-#ifdef __linux__
-SWIFT_RUNTIME_STDLIB_INTERNAL bool _swift_spawnBacktracer(const ArgChar * const *argv, int memserver_fd);
-#else
-SWIFT_RUNTIME_STDLIB_INTERNAL bool _swift_spawnBacktracer(const ArgChar * const *argv);
-#endif
-
-enum class UnwindAlgorithm {
-  Auto = 0,
-  Fast = 1,
-  Precise = 2
-};
-
-enum class OnOffTty {
-  Off = 0,
-  On = 1,
-  TTY = 2
-};
-
-enum class Preset {
-  Auto = -1,
-  Friendly = 0,
-  Medium = 1,
-  Full = 2
-};
-
-enum class ThreadsToShow {
-  Preset = -1,
-  All = 0,
-  Crashed = 1
-};
-
-enum class RegistersToShow {
-  Preset = -1,
-  None = 0,
-  All = 1,
-  Crashed = 2
-};
-
-enum class ImagesToShow {
-  Preset = -1,
-  None = 0,
-  All = 1,
-  Mentioned = 2
-};
-
-enum class SanitizePaths {
-  Preset = -1,
-  Off = 0,
-  On = 1
-};
-
-enum class OutputTo {
-  Auto = -1,
-  Stdout = 0,
-  Stderr = 2,
-};
-
-struct BacktraceSettings {
-  UnwindAlgorithm  algorithm;
-  OnOffTty         enabled;
-  bool             demangle;
-  OnOffTty         interactive;
-  OnOffTty         color;
-  unsigned         timeout;
-  ThreadsToShow    threads;
-  RegistersToShow  registers;
-  ImagesToShow     images;
-  unsigned         limit;
-  unsigned         top;
-  SanitizePaths    sanitize;
-  Preset           preset;
-  bool             cache;
-  OutputTo         outputTo;
-  const char      *swiftBacktracePath;
-};
-
-SWIFT_RUNTIME_STDLIB_INTERNAL BacktraceSettings _swift_backtraceSettings;
-
-inline bool _swift_backtrace_isEnabled() {
-  return _swift_backtraceSettings.enabled == OnOffTty::On;
-}
-
+// Test if a given function is a Swift thunk of some sort.
+//
+// @param mangledName is the name of the symbol to test.
+//
+// @returns true if the function is a thunk.
 SWIFT_RUNTIME_STDLIB_SPI
 bool _swift_backtrace_isThunkFunction(const char *mangledName);
 

stdlib/public/libexec/swift-backtrace/main.swift

@@ -113,6 +113,38 @@ internal struct SwiftBacktrace {
     }
   }
 
+  static func subtract(timespec ts: timespec, from: timespec) -> timespec {
+    var sec = from.tv_sec - ts.tv_sec
+    var nsec = from.tv_nsec - ts.tv_nsec
+    if nsec < 0 {
+      sec -= 1
+      nsec += 1000000000
+    }
+    return timespec(tv_sec: sec, tv_nsec: nsec)
+  }
+
+  // We can't use Foundation here, so there's no String(format:, ...)
+  static func format(duration: timespec) -> String {
+    let centisRounded = (duration.tv_nsec + 5000000) / 10000000
+    let centis = centisRounded % 100
+    let secs = duration.tv_sec + (centisRounded / 100)
+    let d1 = centis / 10
+    let d2 = centis % 10
+
+    return "\(secs).\(d1)\(d2)"
+  }
+
+  static func measureDuration(_ body: () -> ()) -> timespec {
+    var startTime = timespec()
+    var endTime = timespec()
+
+    clock_gettime(CLOCK_MONOTONIC, &startTime)
+    body()
+    clock_gettime(CLOCK_MONOTONIC, &endTime)
+
+    return subtract(timespec: startTime, from: endTime)
+  }
+
   static func usage() {
     print("""
 usage: swift-backtrace [--unwind <algorithm>] [--demangle [<bool>]] [--interactive [<bool>]] [--color [<bool>]] [--timeout <seconds>] [--preset <preset>] [--threads [<bool>]] [--registers <registers>] [--images <images>] [--cache [<bool>]] [--output-to <stream>] --crashinfo <addr>
@@ -460,16 +492,25 @@ Generate a backtrace for the parent process.
     // want to do it *once* for all the backtraces we showed.
     formattingOptions = formattingOptions.showImages(.none)
 
-    target = Target(crashInfoAddr: crashInfoAddr,
-                    limit: args.limit, top: args.top,
-                    cache: args.cache)
+    // Target's initializer fetches and symbolicates backtraces, so
+    // we want to time that part here.
+    let duration = measureDuration {
+      target = Target(crashInfoAddr: crashInfoAddr,
+                      limit: args.limit, top: args.top,
+                      cache: args.cache)
 
-    currentThread = target!.crashingThreadNdx
+      currentThread = target!.crashingThreadNdx
+    }
 
     printCrashLog()
 
     writeln("")
 
+    let formattedDuration = format(duration: duration)
+
+    writeln("Backtrace took \(formattedDuration)s")
+    writeln("")
+
     if args.interactive {
       // Make sure we're line buffered
       setvbuf(stdout, nil, _IOLBF, 0)
@@ -611,7 +652,13 @@ Generate a backtrace for the parent process.
       description = "Program crashed: \(target.signalDescription) at \(hex(target.faultAddress))"
     }
 
-    writeln("")
+    // Clear the message written by the crash handler
+    if args.color {
+      write("\r\u{1b}[0K")
+    } else {
+      write("\r" + String(repeating:" ", count: 80) + "\r")
+    }
+
     writeln(theme.crashReason(description))
 
     var mentionedImages = Set<Int>()

stdlib/public/runtime/Backtrace.cpp

@@ -58,6 +58,8 @@
 #include <cxxabi.h>
 #endif
 
+#include "BacktracePrivate.h"
+
 #define DEBUG_BACKTRACING_SETTINGS 0
 
 #ifndef lengthof
@@ -987,6 +989,57 @@ _swift_spawnBacktracer(const ArgChar * const *argv)
 #endif
 }
 
+// N.B. THIS FUNCTION MUST BE SAFE TO USE FROM A CRASH HANDLER.  On Linux
+// and macOS, that means it must be async-signal-safe.  On Windows, there
+// isn't an equivalent notion but a similar restriction applies.
+SWIFT_RUNTIME_STDLIB_INTERNAL void
+_swift_displayCrashMessage(int signum, const void *pc)
+{
+#if !SWIFT_BACKTRACE_ON_CRASH_SUPPORTED
+  return;
+#else
+  int fd = STDOUT_FILENO;
+
+  if (_swift_backtraceSettings.outputTo == OutputTo::Stderr)
+    fd = STDERR_FILENO;
+
+  const char *intro;
+  if (_swift_backtraceSettings.color == OnOffTty::On) {
+    intro = "\n💣 \033[91mProgram crashed: ";
+  } else {
+    intro = "\n*** Program crashed: ";
+  }
+  write(fd, intro, strlen(intro));
+
+  char sigbuf[30];
+  strcpy(sigbuf, "Signal ");
+  _swift_formatUnsigned((unsigned)signum, sigbuf + 7);
+  write(fd, sigbuf, strlen(sigbuf));
+
+  const char *message;
+  if (!pc) {
+    message = ": Backtracing";
+  } else {
+    message = ": Backtracing from 0x";
+  }
+  write(fd, message, strlen(message));
+
+  if (pc) {
+    char pcbuf[18];
+    _swift_formatAddress(pc, pcbuf);
+    write(fd, pcbuf, strlen(pcbuf));
+  }
+
+  const char *outro;
+  if (_swift_backtraceSettings.color == OnOffTty::On) {
+    outro = "...\033[0m";
+  } else {
+    outro = "...";
+  }
+  write(fd, outro, strlen(outro));
+#endif
+}
+
 } // namespace backtrace
 } // namespace runtime
 } // namespace swift

stdlib/public/runtime/BacktracePrivate.h

@@ -0,0 +1,147 @@
+//===--- BacktraceUtils.h - Private backtracing utilities -------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// Private declarations of the Swift runtime's backtracing code.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_RUNTIME_BACKTRACE_UTILS_H
+#define SWIFT_RUNTIME_BACKTRACE_UTILS_H
+
+#include "swift/Runtime/Config.h"
+#include "swift/shims/Visibility.h"
+
+#include <inttypes.h>
+
+#ifdef _WIN32
+// For DWORD
+#define WIN32_LEAN_AND_MEAN
+#define NOMINMAX
+#include <windows.h>
+
+// For wchar_t
+#include <cwchar>
+#endif
+
+namespace swift {
+namespace runtime {
+namespace backtrace {
+
+#ifdef _WIN32
+typedef wchar_t ArgChar;
+typedef DWORD ErrorCode;
+#else
+typedef char ArgChar;
+typedef int ErrorCode;
+#endif
+
+enum class UnwindAlgorithm {
+  Auto = 0,
+  Fast = 1,
+  Precise = 2
+};
+
+enum class OnOffTty {
+  Off = 0,
+  On = 1,
+  TTY = 2
+};
+
+enum class Preset {
+  Auto = -1,
+  Friendly = 0,
+  Medium = 1,
+  Full = 2
+};
+
+enum class ThreadsToShow {
+  Preset = -1,
+  All = 0,
+  Crashed = 1
+};
+
+enum class RegistersToShow {
+  Preset = -1,
+  None = 0,
+  All = 1,
+  Crashed = 2
+};
+
+enum class ImagesToShow {
+  Preset = -1,
+  None = 0,
+  All = 1,
+  Mentioned = 2
+};
+
+enum class SanitizePaths {
+  Preset = -1,
+  Off = 0,
+  On = 1
+};
+
+enum class OutputTo {
+  Auto = -1,
+  Stdout = 0,
+  Stderr = 2,
+};
+
+struct BacktraceSettings {
+  UnwindAlgorithm  algorithm;
+  OnOffTty         enabled;
+  bool             demangle;
+  OnOffTty         interactive;
+  OnOffTty         color;
+  unsigned         timeout;
+  ThreadsToShow    threads;
+  RegistersToShow  registers;
+  ImagesToShow     images;
+  unsigned         limit;
+  unsigned         top;
+  SanitizePaths    sanitize;
+  Preset           preset;
+  bool             cache;
+  OutputTo         outputTo;
+  const char      *swiftBacktracePath;
+};
+
+SWIFT_RUNTIME_STDLIB_INTERNAL BacktraceSettings _swift_backtraceSettings;
+
+inline bool _swift_backtrace_isEnabled() {
+  return _swift_backtraceSettings.enabled == OnOffTty::On;
+}
+
+SWIFT_RUNTIME_STDLIB_INTERNAL ErrorCode _swift_installCrashHandler();
+
+#ifdef __linux__
+SWIFT_RUNTIME_STDLIB_INTERNAL bool _swift_spawnBacktracer(const ArgChar * const *argv, int memserver_fd);
+#else
+SWIFT_RUNTIME_STDLIB_INTERNAL bool _swift_spawnBacktracer(const ArgChar * const *argv);
+#endif
+
+SWIFT_RUNTIME_STDLIB_INTERNAL void _swift_displayCrashMessage(int signum, const void *pc);
+
+SWIFT_RUNTIME_STDLIB_INTERNAL
+void _swift_formatAddress(uintptr_t addr, char buffer[18]);
+
+inline void _swift_formatAddress(const void *ptr, char buffer[18]) {
+  _swift_formatAddress(reinterpret_cast<uintptr_t>(ptr), buffer);
+}
+
+SWIFT_RUNTIME_STDLIB_INTERNAL
+void _swift_formatUnsigned(unsigned u, char buffer[22]);
+
+} // namespace backtrace
+} // namespace runtime
+} // namespace swift
+
+#endif // SWIFT_RUNTIME_BACKTRACE_UTILS_H

stdlib/public/runtime/BacktraceUtils.cpp

@@ -0,0 +1,74 @@
+//===--- BacktraceUtils.cpp - Private backtracing utilities -----*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines some async-signal-safe formatting functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "BacktracePrivate.h"
+
+namespace swift {
+namespace runtime {
+namespace backtracing {
+
+// We can't call sprintf() here because we're in a signal handler,
+// so we need to be async-signal-safe.
+SWIFT_RUNTIME_STDLIB_INTERNAL void
+_swift_formatAddress(uintptr_t addr, char buffer[18])
+{
+  char *ptr = buffer + 18;
+  *--ptr = '\0';
+  while (ptr > buffer) {
+    char digit = '0' + (addr & 0xf);
+    if (digit > '9')
+      digit += 'a' - '0' - 10;
+    *--ptr = digit;
+    addr >>= 4;
+    if (!addr)
+      break;
+  }
+
+  // Left-justify in the buffer
+  if (ptr > buffer) {
+    char *pt2 = buffer;
+    while (*ptr)
+      *pt2++ = *ptr++;
+    *pt2++ = '\0';
+  }
+}
+
+// See above; we can't use sprintf() here.
+SWIFT_RUNTIME_STDLIB_INTERNAL void
+_swift_formatUnsigned(unsigned u, char buffer[22])
+{
+  char *ptr = buffer + 22;
+  *--ptr = '\0';
+  while (ptr > buffer) {
+    char digit = '0' + (u % 10);
+    *--ptr = digit;
+    u /= 10;
+    if (!u)
+      break;
+  }
+
+  // Left-justify in the buffer
+  if (ptr > buffer) {
+    char *pt2 = buffer;
+    while (*ptr)
+      *pt2++ = *ptr++;
+    *pt2++ = '\0';
+  }
+}
+
+} // namespace backtracing
+} // namespace runtime
+} // namespace swift

stdlib/public/runtime/CMakeLists.txt

@@ -88,6 +88,7 @@ set(swift_runtime_threading_sources
 
 set(swift_runtime_backtracing_sources
   Backtrace.cpp
+  BacktraceUtils.cpp
   CrashHandlerMacOS.cpp
   CrashHandlerLinux.cpp)
 

stdlib/public/runtime/CrashHandlerLinux.cpp

@@ -45,6 +45,8 @@
 
 #include <cstring>
 
+#include "BacktracePrivate.h"
+
 // Run the memserver in a thread (0) or separate process (1)
 #define MEMSERVER_USE_PROCESS 0
 
@@ -67,7 +69,6 @@ void wait_paused(uint32_t expected, const struct timespec *timeout);
 int  memserver_start();
 int  memserver_entry(void *);
 bool run_backtracer(int fd);
-void format_unsigned(unsigned u, char buffer[22]);
 
 ssize_t safe_read(int fd, void *buf, size_t len) {
   uint8_t *ptr = (uint8_t *)buf;
@@ -231,8 +232,30 @@ handle_fatal_signal(int signum,
   // Start the memory server
   int fd = memserver_start();
 
+  // Display a progress message
+  void *pc = 0;
+  ucontext_t *ctx = (ucontext_t *)uctx;
+
+#if defined(__x86_64__)
+  pc = (void *)(ctx->uc_mcontext.gregs[REG_RIP]);
+#elif defined(__i386__)
+  pc = (void *)(ctx->uc_mcontext.gregs[REG_EIP]);
+#elif defined(__arm64__)
+  pc = (void *)(ctx->uc_mcontext.pc);
+#elif defined(__arm__)
+  pc = (void *)(ctx->uc_mcontext.gprs[15]);
+#endif
+
+  _swift_displayCrashMessage(signum, pc);
+
   // Actually start the backtracer
-  run_backtracer(fd);
+  if (!run_backtracer(fd)) {
+    const char *message = "\n\nBacktracing failed\n";
+    if (_swift_backtraceSettings.outputTo == OutputTo::Stderr)
+      write(STDERR_FILENO, message, strlen(message));
+    else
+      write(STDOUT_FILENO, message, strlen(message));
+  }
 
 #if !MEMSERVER_USE_PROCESS
   /* If the memserver is in-process, it may have set signal handlers,
@@ -327,8 +350,8 @@ signal_for_suspend(int pid, int tid)
   char pid_buffer[22];
   char tid_buffer[22];
 
-  format_unsigned((unsigned)pid, pid_buffer);
-  format_unsigned((unsigned)tid, tid_buffer);
+  _swift_formatUnsigned((unsigned)pid, pid_buffer);
+  _swift_formatUnsigned((unsigned)tid, tid_buffer);
 
   char status_file[6 + 22 + 6 + 22 + 7 + 1];
 
@@ -788,60 +811,6 @@ const char *backtracer_argv[] = {
   NULL
 };
 
-// We can't call sprintf() here because we're in a signal handler,
-// so we need to be async-signal-safe.
-void
-format_address(uintptr_t addr, char buffer[18])
-{
-  char *ptr = buffer + 18;
-  *--ptr = '\0';
-  while (ptr > buffer) {
-    char digit = '0' + (addr & 0xf);
-    if (digit > '9')
-      digit += 'a' - '0' - 10;
-    *--ptr = digit;
-    addr >>= 4;
-    if (!addr)
-      break;
-  }
-
-  // Left-justify in the buffer
-  if (ptr > buffer) {
-    char *pt2 = buffer;
-    while (*ptr)
-      *pt2++ = *ptr++;
-    *pt2++ = '\0';
-  }
-}
-void
-format_address(const void *ptr, char buffer[18])
-{
-  format_address(reinterpret_cast<uintptr_t>(ptr), buffer);
-}
-
-// See above; we can't use sprintf() here.
-void
-format_unsigned(unsigned u, char buffer[22])
-{
-  char *ptr = buffer + 22;
-  *--ptr = '\0';
-  while (ptr > buffer) {
-    char digit = '0' + (u % 10);
-    *--ptr = digit;
-    u /= 10;
-    if (!u)
-      break;
-  }
-
-  // Left-justify in the buffer
-  if (ptr > buffer) {
-    char *pt2 = buffer;
-    while (*ptr)
-      *pt2++ = *ptr++;
-    *pt2++ = '\0';
-  }
-}
-
 const char *
 trueOrFalse(bool b) {
   return b ? "true" : "false";
@@ -949,15 +918,15 @@ run_backtracer(int memserver_fd)
 
   backtracer_argv[28] = trueOrFalse(_swift_backtraceSettings.cache);
 
-  format_unsigned(_swift_backtraceSettings.timeout, timeout_buf);
+  _swift_formatUnsigned(_swift_backtraceSettings.timeout, timeout_buf);
 
   if (_swift_backtraceSettings.limit < 0)
     std::strcpy(limit_buf, "none");
   else
-    format_unsigned(_swift_backtraceSettings.limit, limit_buf);
+    _swift_formatUnsigned(_swift_backtraceSettings.limit, limit_buf);
 
-  format_unsigned(_swift_backtraceSettings.top, top_buf);
-  format_address(&crashInfo, addr_buf);
+  _swift_formatUnsigned(_swift_backtraceSettings.top, top_buf);
+  _swift_formatAddress(&crashInfo, addr_buf);
 
   // Actually execute it
   return _swift_spawnBacktracer(backtracer_argv, memserver_fd);

stdlib/public/runtime/CrashHandlerMacOS.cpp

@@ -44,6 +44,8 @@
 
 #include <cstring>
 
+#include "BacktracePrivate.h"
+
 #ifndef lengthof
 #define lengthof(x)     (sizeof(x) / sizeof(x[0]))
 #endif
@@ -225,9 +227,33 @@ handle_fatal_signal(int signum,
   crashInfo.fault_address = (uint64_t)pinfo->si_addr;
   crashInfo.mctx = (uint64_t)(((ucontext_t *)uctx)->uc_mcontext);
 
+  // Display a progress message
+  void *pc = 0;
+  ucontext_t *ctx = (ucontext_t *)uctx;
+
+#ifdef __DARWIN_UNIX03
+#define CTX_MEMBER(x) __##x
+#else
+#define CTX_MEMBER(x) x
+#endif
+
+#if defined(__x86_64__)
+  pc = (void *)(ctx->uc_mcontext->CTX_MEMBER(ss).CTX_MEMBER(rip));
+#elif defined(__arm64__)
+  pc = (void *)(ctx->uc_mcontext->CTX_MEMBER(ss).CTX_MEMBER(pc));
+#endif
+
+  _swift_displayCrashMessage(signum, pc);
+
   /* Start the backtracer; this will suspend the process, so there's no need
      to try to suspend other threads from here. */
-  run_backtracer();
+  if (!run_backtracer()) {
+    const char *message = "\n\nBacktracing failed\n";
+    if (_swift_backtraceSettings.outputTo == OutputTo::Stderr)
+      write(STDERR_FILENO, message, strlen(message));
+    else
+      write(STDOUT_FILENO, message, strlen(message));
+  }
 
   // Restart the other threads
   resume_other_threads();
@@ -275,60 +301,6 @@ const char *backtracer_argv[] = {
   NULL
 };
 
-// We can't call sprintf() here because we're in a signal handler,
-// so we need to be async-signal-safe.
-void
-format_address(uintptr_t addr, char buffer[18])
-{
-  char *ptr = buffer + 18;
-  *--ptr = '\0';
-  while (ptr > buffer) {
-    char digit = '0' + (addr & 0xf);
-    if (digit > '9')
-      digit += 'a' - '0' - 10;
-    *--ptr = digit;
-    addr >>= 4;
-    if (!addr)
-      break;
-  }
-
-  // Left-justify in the buffer
-  if (ptr > buffer) {
-    char *pt2 = buffer;
-    while (*ptr)
-      *pt2++ = *ptr++;
-    *pt2++ = '\0';
-  }
-}
-void
-format_address(const void *ptr, char buffer[18])
-{
-  format_address(reinterpret_cast<uintptr_t>(ptr), buffer);
-}
-
-// See above; we can't use sprintf() here.
-void
-format_unsigned(unsigned u, char buffer[22])
-{
-  char *ptr = buffer + 22;
-  *--ptr = '\0';
-  while (ptr > buffer) {
-    char digit = '0' + (u % 10);
-    *--ptr = digit;
-    u /= 10;
-    if (!u)
-      break;
-  }
-
-  // Left-justify in the buffer
-  if (ptr > buffer) {
-    char *pt2 = buffer;
-    while (*ptr)
-      *pt2++ = *ptr++;
-    *pt2++ = '\0';
-  }
-}
-
 const char *
 trueOrFalse(bool b) {
   return b ? "true" : "false";
@@ -436,15 +408,15 @@ run_backtracer()
 
   backtracer_argv[28] = trueOrFalse(_swift_backtraceSettings.cache);
 
-  format_unsigned(_swift_backtraceSettings.timeout, timeout_buf);
+  _swift_formatUnsigned(_swift_backtraceSettings.timeout, timeout_buf);
 
   if (_swift_backtraceSettings.limit < 0)
     std::strcpy(limit_buf, "none");
   else
-    format_unsigned(_swift_backtraceSettings.limit, limit_buf);
+    _swift_formatUnsigned(_swift_backtraceSettings.limit, limit_buf);
 
-  format_unsigned(_swift_backtraceSettings.top, top_buf);
-  format_address(&crashInfo, addr_buf);
+  _swift_formatUnsigned(_swift_backtraceSettings.top, top_buf);
+  _swift_formatAddress(&crashInfo, addr_buf);
 
   // Actually execute it
   return _swift_spawnBacktracer(backtracer_argv);

stdlib/public/runtime/Errors.cpp

@@ -34,7 +34,6 @@
 
 #include "ImageInspection.h"
 #include "swift/Demangling/Demangle.h"
-#include "swift/Runtime/Backtrace.h"
 #include "swift/Runtime/Debug.h"
 #include "swift/Runtime/Portability.h"
 #include "swift/Runtime/Win32.h"
@@ -71,6 +70,8 @@
 #include "swift/Runtime/Atomic.h"
 #endif // SWIFT_HAVE_CRASHREPORTERCLIENT
 
+#include "BacktracePrivate.h"
+
 namespace FatalErrorFlags {
 enum: uint32_t {
   ReportBacktrace = 1 << 0