Use llvm-symbolizer to symbolize LLVM/Clang crash dumps.

This change modifies fatal signal handler used in LLVM tools.
Now it attempts to find llvm-symbolizer binary and communicates
with it in order to turn instruction addresses into
function/file/line info entries. This should significantly improve
stack traces readability in Debug builds.

This feature only works on selected platforms (including Darwin
and Linux). If the symbolization fails for some reason, signal
handler will fallback to the original behavior.

Reviewed in http://reviews.llvm.org/D5610

llvm-svn: 219354

1 files changed, 139 insertions, 1 deletions

diff --git a/llvm/lib/Support/Unix/Signals.inc b/llvm/lib/Support/Unix/Signals.inc
index 592674e..9291b617 100644
--- a/llvm/lib/Support/Unix/Signals.inc
+++ b/llvm/lib/Support/Unix/Signals.inc
@@ -14,9 +14,14 @@
 
 #include "Unix.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FileUtilities.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Mutex.h"
+#include "llvm/Support/Program.h"
 #include "llvm/Support/UniqueLock.h"
-#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <string>
 #include <vector>
@@ -38,6 +43,9 @@
 #if HAVE_MACH_MACH_H
 #include <mach/mach.h>
 #endif
+#if HAVE_LINK_H
+#include <link.h>
+#endif
 
 using namespace llvm;
 
@@ -264,6 +272,134 @@ void llvm::sys::AddSignalHandler(void (*FnPtr)(void *), void *Cookie) {
   RegisterHandlers();
 }
 
+#if HAVE_LINK_H
+struct DlIteratePhdrData {
+  void **StackTrace;
+  int depth;
+  bool first;
+  const char **modules;
+  intptr_t *offsets;
+  const char *main_exec_name;
+};
+
+static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
+  DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
+  const char *name = data->first ? data->main_exec_name : info->dlpi_name;
+  data->first = false;
+  for (int i = 0; i < info->dlpi_phnum; i++) {
+    const ElfW(Phdr) *phdr = &info->dlpi_phdr[i];
+    if (phdr->p_type != PT_LOAD)
+      continue;
+    intptr_t beg = info->dlpi_addr + phdr->p_vaddr;
+    intptr_t end = beg + phdr->p_memsz;
+    for (int j = 0; j < data->depth; j++) {
+      if (data->modules[j])
+        continue;
+      intptr_t addr = (intptr_t)data->StackTrace[j];
+      if (beg <= addr && addr < end) {
+        data->modules[j] = name;
+        data->offsets[j] = addr - info->dlpi_addr;
+      }
+    }
+  }
+  return 0;
+}
+
+static bool findModulesAndOffsets(void **StackTrace, int Depth,
+                                  const char **Modules, intptr_t *Offsets,
+                                  const char *MainExecutableName) {
+  DlIteratePhdrData data = {StackTrace, Depth,   true,
+                            Modules,    Offsets, MainExecutableName};
+  dl_iterate_phdr(dl_iterate_phdr_cb, &data);
+  return true;
+}
+#else
+static bool findModulesAndOffsets(void **StackTrace, int Depth,
+                                  const char **Modules, intptr_t *Offsets,
+                                  const char *MainExecutableName) {
+  return false;
+}
+#endif
+
+static bool printSymbolizedStackTrace(void **StackTrace, int Depth, FILE *FD) {
+  // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
+  // into actual instruction addresses.
+  // Use llvm-symbolizer tool to symbolize the stack traces.
+  std::string LLVMSymbolizerPath = sys::FindProgramByName("llvm-symbolizer");
+  if (LLVMSymbolizerPath.empty())
+    return false;
+  // We don't know argv0 or the address of main() at this point, but try
+  // to guess it anyway (it's possible on some platforms).
+  std::string MainExecutableName = sys::fs::getMainExecutable(nullptr, nullptr);
+  if (MainExecutableName.empty() ||
+      MainExecutableName.find("llvm-symbolizer") != std::string::npos)
+    return false;
+
+  std::vector<const char *> Modules(Depth, nullptr);
+  std::vector<intptr_t> Offsets(Depth, 0);
+  if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
+                             MainExecutableName.c_str()))
+    return false;
+  int InputFD;
+  SmallString<32> InputFile, OutputFile;
+  sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
+  sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
+  FileRemover InputRemover(InputFile.c_str());
+  FileRemover OutputRemover(OutputFile.c_str());
+  std::vector<const StringRef *> Redirects(3, nullptr);
+  StringRef InputFileStr(InputFile);
+  StringRef OutputFileStr(OutputFile);
+  StringRef StderrFileStr;
+  Redirects[0] = &InputFileStr;
+  Redirects[1] = &OutputFileStr;
+  Redirects[2] = &StderrFileStr;
+
+  {
+    raw_fd_ostream Input(InputFD, true);
+    for (int i = 0; i < Depth; i++) {
+      if (Modules[i])
+        Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
+    }
+  }
+
+  const char *args[] = {"llvm-symbolizer", nullptr};
+  int RunResult =
+      sys::ExecuteAndWait(LLVMSymbolizerPath, args, nullptr, Redirects.data());
+  if (RunResult != 0)
+    return false;
+
+  auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
+  if (std::error_code Err = OutputBuf.getError())
+    return false;
+  StringRef Output = OutputBuf.get()->getBuffer();
+  SmallVector<StringRef, 32> Lines;
+  Output.split(Lines, "\n");
+  auto CurLine = Lines.begin();
+  int frame_no = 0;
+  for (int i = 0; i < Depth; i++) {
+    if (!Modules[i]) {
+      fprintf(FD, "#%d %p\n", frame_no++, StackTrace[i]);
+      continue;
+    }
+    // Read pairs of lines (function name and file/line info) until we
+    // encounter empty line.
+    for (;;) {
+      StringRef FunctionName = *CurLine++;
+      if (FunctionName.empty())
+        break;
+      fprintf(FD, "#%d %p ", frame_no++, StackTrace[i]);
+      if (!FunctionName.startswith("??"))
+        fprintf(FD, "%s ", FunctionName.str().c_str());
+      StringRef FileLineInfo = *CurLine++;
+      if (!FileLineInfo.startswith("??"))
+        fprintf(FD, "%s", FileLineInfo.str().c_str());
+      else
+        fprintf(FD, "(%s+%p)", Modules[i], (void *)Offsets[i]);
+      fprintf(FD, "\n");
+    }
+  }
+  return true;
+}
 
 // PrintStackTrace - In the case of a program crash or fault, print out a stack
 // trace so that the user has an indication of why and where we died.
@@ -276,6 +412,8 @@ void llvm::sys::PrintStackTrace(FILE *FD) {
   // Use backtrace() to output a backtrace on Linux systems with glibc.
   int depth = backtrace(StackTrace,
                         static_cast<int>(array_lengthof(StackTrace)));
+  if (printSymbolizedStackTrace(StackTrace, depth, FD))
+    return;
 #if HAVE_DLFCN_H && __GNUG__
   int width = 0;
   for (int i = 0; i < depth; ++i) {