[llvm-symbolizer] Omit stderr output when symbolizing a stacktrace

[aganea]

Summary

As discussed previously, don't print errors when symbolizing a stack trace:

LLVMSymbolizer: error reading file: 'ucrtbased.pdb': no such file or directory
LLVMSymbolizer: error reading file: 'kernel32.pdb': no such file or directory
LLVMSymbolizer: error reading file: 'ntdll.pdb': no such file or directory
#0 0x00007ff71c62501c HandleAbort f:\svn\llvm\lib\support\windows\signals.inc:409:0
#1 0x00007ffe6510bba1 (C:\WINDOWS\SYSTEM32\ucrtbased.dll+0x6bba1)
#2 0x00007ffe6510d7f9 (C:\WINDOWS\SYSTEM32\ucrtbased.dll+0x6d7f9)

...now shows:

#0 0x00007ff71c62501c HandleAbort f:\svn\llvm\lib\support\windows\signals.inc:409:0
#1 0x00007ffe6510bba1 (C:\WINDOWS\SYSTEM32\ucrtbased.dll+0x6bba1)
#2 0x00007ffe6510d7f9 (C:\WINDOWS\SYSTEM32\ucrtbased.dll+0x6d7f9)

I've also aligned the count at the begining of the line (I can commit two separate patches if you wish):

 #0 0x00007ff7e7004fbc HandleAbort f:\svn\llvm\lib\support\windows\signals.inc:409:0
 #1 0x00007ffe674fbba1 (C:\WINDOWS\SYSTEM32\ucrtbased.dll+0x6bba1)
                        (...)
 #9 0x00007ff7e720b3c1 <lambda_0a1b45eabab73a8e6866a119e7429fe9>::operator() f:\svn\lld\coff\pdb.cpp:1227:0
#10 0x00007ff7e71f1b4e llvm::codeview::forEachCodeViewRecord f:\svn\llvm\include\llvm\debuginfo\codeview\cvrecord.h:77:0
#11 0x00007ff7e71d7ea3 `anonymous namespace'::PDBLinker::mergeSymbolRecords f:\svn\lld\coff\pdb.cpp:1197:0

[rnk]

lgtm

Thanks for dealing with this, it has been annoying me for years at this point.

llvm/trunk/lib/Support/Signals.cpp

 #include "llvm/Support/Signals.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/FormatAdapters.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Mutex.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/StringSaver.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/Options.h"
 #include <vector>
FileRemover OutputRemover(OutputFile.c_str());
     raw_fd_ostream Input(InputFD, true);
     for (int i = 0; i < Depth; i++) {
       if (Modules[i])
         Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
     }
   }
 
   Optional<StringRef> Redirects[] = {StringRef(InputFile),
-                                     StringRef(OutputFile), llvm::None};
+                                     StringRef(OutputFile), ""};
   StringRef Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
 #ifdef _WIN32
                       // Pass --relative-address on Windows so that we don't
                       // have to add ImageBase from PE file.
                       // FIXME: Make this the default for llvm-symbolizer.
                       "--relative-address",
 #endif
                       "--demangle"};
   int RunResult =
       sys::ExecuteAndWait(LLVMSymbolizerPath, Args, None, Redirects);
   if (RunResult != 0)
     return false;
 
   // This report format is based on the sanitizer stack trace printer.  See
   // sanitizer_stacktrace_printer.cc in compiler-rt.
   auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
   if (!OutputBuf)
     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++) {
+    auto PrintLineHeader = [&]() {
+      OS << right_justify(formatv("#{0}", frame_no++).str(),
+                          std::log10(Depth) + 2)
+         << ' ' << format_ptr(StackTrace[i]) << ' ';
+    };
     if (!Modules[i]) {
-      OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << '\n';
+      PrintLineHeader();
+      OS << '\n';
       continue;
     }
     // Read pairs of lines (function name and file/line info) until we
     // encounter empty line.
     for (;;) {
       if (CurLine == Lines.end())
         return false;
       StringRef FunctionName = *CurLine++;
       if (FunctionName.empty())
         break;
-      OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << ' ';
+      PrintLineHeader();
       if (!FunctionName.startswith("??"))
         OS << FunctionName << ' ';
       if (CurLine == Lines.end())
         return false;
       StringRef FileLineInfo = *CurLine++;
       if (!FileLineInfo.startswith("??"))
         OS << FileLineInfo;
       else