Tools emit the bug report URL on crash

[gbreynoo]

Summary

When Clang crashes a useful message is output:

"PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script."

A similar message could be output for all tools.

I am unfamiliar with this area of LLVM. Any suggestions would be appreciated, particularly regarding the testing of this change.

[gbreynoo]

ping

[jhenderson]

As this code is currently untested already, and testing it would require exploiting an existing crash (there should be none - any crashes that currently occur should be fixed), or deliberately introducing one, I think it is sufficient if you test it manually. As such, please post an example of the output you would get for a crash from LLD or another tool such as llvm-readobj. Finally, can clang be changed to make use of the same code? It seems silly to repeat the exact same string in the LLVM code base in two different places.

[gbreynoo]

Removed Clangs use of the same message.

[gbreynoo]

Hi James,

After forcing a crash in llvm-readobj here is the output:

PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace
Stack dump:
0.      Program arguments: F:\llvm-git\build\Debug\bin\llvm-readobj.exe
#0 0x00007ff60572b6d4 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x114b6d4)
#1 0x00007ff60572b874 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x114b874)
#2 0x00007ff604905623 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x325623)
#3 0x00007ff60572bd04 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x114bd04)
#4 0x00007ff60572bbee (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x114bbee)
#5 0x00007ff60572baae (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x114baae)
#6 0x00007ff60572bd99 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x114bd99)
#7 0x00007ffd61a47974 (C:\WINDOWS\System32\KERNEL32.DLL+0x17974)
#8 0x00007ffd61cba261 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x6a261)

After looking into Clang I saw that both messages would be output:

PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace
Stack dump:
0.      Program arguments: F:\llvm-git\build\Debug\bin\clang.exe -target i386-apple-darwin10 -flto -S -g F:\llvm-git\llvm-project\clang\test\CodeGen\2009-10-20-GlobalDebug.c
 #0 0x00007ff7a5698894 (F:\llvm-git\build\Debug\bin\clang.exe+0xb128894)
 #1 0x00007ff7a5698a34 (F:\llvm-git\build\Debug\bin\clang.exe+0xb128a34)
 #2 0x00007ff79a9fd29a (F:\llvm-git\build\Debug\bin\clang.exe+0x48d29a)
 #3 0x00007ff7a0086e56 (F:\llvm-git\build\Debug\bin\clang.exe+0x5b16e56)
 #4 0x00007ff7a0086158 (F:\llvm-git\build\Debug\bin\clang.exe+0x5b16158)
 #5 0x00007ff79ee69fee (F:\llvm-git\build\Debug\bin\clang.exe+0x48f9fee)
 #6 0x00007ff79ee695ff (F:\llvm-git\build\Debug\bin\clang.exe+0x48f95ff)
 #7 0x00007ff7a0082c3a (F:\llvm-git\build\Debug\bin\clang.exe+0x5b12c3a)
 #8 0x00007ff79ffbb1fd (F:\llvm-git\build\Debug\bin\clang.exe+0x5a4b1fd)
 #9 0x00007ff79ffbb439 (F:\llvm-git\build\Debug\bin\clang.exe+0x5a4b439)
#10 0x00007ff79ff55259 (F:\llvm-git\build\Debug\bin\clang.exe+0x59e5259)
#11 0x00007ff79a9fe6c3 (F:\llvm-git\build\Debug\bin\clang.exe+0x48e6c3)
#12 0x00007ff7a56998a4 (F:\llvm-git\build\Debug\bin\clang.exe+0xb1298a4)
#13 0x00007ff7a569974e (F:\llvm-git\build\Debug\bin\clang.exe+0xb12974e)
#14 0x00007ff7a569960e (F:\llvm-git\build\Debug\bin\clang.exe+0xb12960e)
#15 0x00007ff7a5699939 (F:\llvm-git\build\Debug\bin\clang.exe+0xb129939)
#16 0x00007ffd61a47974 (C:\WINDOWS\System32\KERNEL32.DLL+0x17974)
#17 0x00007ffd61cba261 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x6a261)
clang: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 11.0.0 (https://github.com/llvm/llvm-project.git 7202d9cde9d23ba94c7f09fd6b5eafc437136542)
Target: i386-apple-darwin10
Thread model: posix
InstalledDir: F:\llvm-git\build\Debug\bin
clang: note: diagnostic msg: PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
clang: note: diagnostic msg: Error generating preprocessed source(s).

The new diff includes the removal of the second message, and I have added reviewers who have made changes in the area.

[probinson]

clang/lib/Driver/Driver.cpp

1273

No, for clang crashes we want the message to say all these things. The driver makes an effort to produce preprocessed source and a run script; it's hard to diagnose a crash without them.

[gbreynoo]

After Paul's comment, a custom message can now be used to replace the generic one.

[gbreynoo]

Thanks Paul.

Output is now as below:

General output:

PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace
Stack dump:
0.      Program arguments: F:\llvm-git\build\Debug\bin\llvm-readobj.exe
#0 0x00007ff6d55259c4 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x11559c4)
#1 0x00007ff6d5525b64 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x1155b64)
#2 0x00007ff6d46f83f3 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x3283f3)
#3 0x00007ff6d5525ff4 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x1155ff4)
#4 0x00007ff6d5525ede (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x1155ede)
#5 0x00007ff6d5525d9e (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x1155d9e)
#6 0x00007ff6d5526089 (F:\llvm-git\build\Debug\bin\llvm-readobj.exe+0x1156089)
#7 0x00007ffe44fb7974 (C:\WINDOWS\System32\KERNEL32.DLL+0x17974)
#8 0x00007ffe470fa261 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x6a261)

Clang specific:

PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: F:\llvm-git\build\Debug\bin\clang.exe -target i386-apple-darwin10 -flto -S -g F:\llvm-git\llvm-project\clang\test\CodeGen\2009-10-20-GlobalDebug.c
 #0 0x00007ff76a655274 (F:\llvm-git\build\Debug\bin\clang.exe+0xb305274)
 #1 0x00007ff76a655414 (F:\llvm-git\build\Debug\bin\clang.exe+0xb305414)
 #2 0x00007ff75f804234 (F:\llvm-git\build\Debug\bin\clang.exe+0x4b4234)
 #3 0x00007ff75f7ebf45 (F:\llvm-git\build\Debug\bin\clang.exe+0x49bf45)
 #4 0x00007ff764f1ef36 (F:\llvm-git\build\Debug\bin\clang.exe+0x5bcef36)
 #5 0x00007ff764f1e238 (F:\llvm-git\build\Debug\bin\clang.exe+0x5bce238)
 #6 0x00007ff763cdea2e (F:\llvm-git\build\Debug\bin\clang.exe+0x498ea2e)
 #7 0x00007ff763cde03f (F:\llvm-git\build\Debug\bin\clang.exe+0x498e03f)
 #8 0x00007ff764f1ad1a (F:\llvm-git\build\Debug\bin\clang.exe+0x5bcad1a)
 #9 0x00007ff764e5303d (F:\llvm-git\build\Debug\bin\clang.exe+0x5b0303d)
#10 0x00007ff764e53279 (F:\llvm-git\build\Debug\bin\clang.exe+0x5b03279)
#11 0x00007ff764ded0d9 (F:\llvm-git\build\Debug\bin\clang.exe+0x5a9d0d9)
#12 0x00007ff75f7ed1b7 (F:\llvm-git\build\Debug\bin\clang.exe+0x49d1b7)
#13 0x00007ff76a656034 (F:\llvm-git\build\Debug\bin\clang.exe+0xb306034)
#14 0x00007ff76a655ede (F:\llvm-git\build\Debug\bin\clang.exe+0xb305ede)
#15 0x00007ff76a655d9e (F:\llvm-git\build\Debug\bin\clang.exe+0xb305d9e)
#16 0x00007ff76a6560c9 (F:\llvm-git\build\Debug\bin\clang.exe+0xb3060c9)
#17 0x00007ffe44fb7974 (C:\WINDOWS\System32\KERNEL32.DLL+0x17974)
#18 0x00007ffe470fa261 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x6a261)
clang: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 11.0.0 (https://github.com/llvm/llvm-project.git fc2a5ef9c8754fe3fbdf96483901ca3f13406b35)
Target: i386-apple-darwin10
Thread model: posix
InstalledDir: F:\llvm-git\build\Debug\bin
clang: note: diagnostic msg: Error generating preprocessed source(s).

[jhenderson]

clang/lib/Driver/Driver.cpp

1273

@probinson - what are your thoughts on the latest version? Note that the output style is slightly different from before, but the message is now the same.

llvm/include/llvm/Support/PrettyStackTrace.h

42

msg -> Msg
SetCustomBugReportMsg -> setBugReportMsg

llvm/lib/Support/PrettyStackTrace.cpp

145

static const char *BugReportMsg;

Why not just have this set to the default in the first place, and overwrite it if somebody needs to? That'll remove the need for the new if in the CrashHandler function.

147

No need for the explicit llvm:: - you are inside a using namespace llvm file.

Also msg -> Msg.

[probinson]

Messaging looks fine now. Final ok left to James.

llvm/lib/Support/PrettyStackTrace.cpp

158

This wants a trailing fullstop.

[gbreynoo]

Changes made in response to James' comments

• Corrected casing of Msg
• Renamed setBugReportMsg
• Set default string

[gbreynoo]

llvm/lib/Support/PrettyStackTrace.cpp

147

I've found it is required, it's also consistent the other global functions in this file.

[jhenderson]

llvm/include/llvm/Support/PrettyStackTrace.h

42

The second half of this hasn't been properly addressed. Function names should start with a lower-case letter (see the LLVM coding standards). The other functions use an older style, and in general I think we should avoid adding more with the wrong style.

llvm/lib/Support/PrettyStackTrace.cpp

145

Again, this hasn't been properly addresssed. This should use an upper-case letter for the first letter of variable names. Please see the coding standards.

[gbreynoo]

Apologies James, this fixes the case issues.

[jhenderson]

LGTM.

[MaskRay]

llvm/lib/Support/PrettyStackTrace.cpp

145

static const char BugReportMsg[] = ...

static const char *BugReportMsg defines a writable variable.

In IR, the former does not have the unnamed_addr attribute while the latter has. The latter can lower to .rodata.str1.1 (SHF_MERGE | SHF_STRINGS) which can be optimized by the linker. This is nuance and the optimization probably weighs nothing (it is hardly to think there will be another thing having the same byte sequence.) The former just seems more correct.

[MaskRay]

llvm/lib/Support/PrettyStackTrace.cpp

145

Nevermind. I did not see setBugReportMsg

[leonardchan]

Hi. This patch seems to cause the undefined symbol error we're seeing when linking clang:

FAILED: bin/clang-11 
: && /b/s/w/ir/k/cipd/bin/clang++ --sysroot=/b/s/w/ir/k/cipd/linux-amd64  -I/b/s/w/ir/k/recipe_cleanup/clangzmv99P/zlib_install/include -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wno-comment -Wstring-conversion -fdiagnostics-color -ffunction-sections -fdata-sections -ffile-prefix-map=/b/s/w/ir/k/recipe_cleanup/clangzmv99P/llvm_build_dir=../recipe_cleanup/clangzmv99P/llvm_build_dir -ffile-prefix-map=/b/s/w/ir/k/llvm-project/= -no-canonical-prefixes -fno-common -Woverloaded-virtual -Wno-nested-anon-types -O3  -static-libstdc++ -fuse-ld=lld -Wl,--color-diagnostics -Wl,-allow-shlib-undefined    -Wl,-O3 -Wl,--gc-sections tools/clang/tools/driver/CMakeFiles/clang.dir/driver.cpp.o tools/clang/tools/driver/CMakeFiles/clang.dir/cc1_main.cpp.o tools/clang/tools/driver/CMakeFiles/clang.dir/cc1as_main.cpp.o tools/clang/tools/driver/CMakeFiles/clang.dir/cc1gen_reproducer_main.cpp.o  -o bin/clang-11  -Wl,-rpath,"\$ORIGIN/../lib" lib/libLLVMX86CodeGen.a lib/libLLVMX86AsmParser.a lib/libLLVMX86Desc.a lib/libLLVMX86Disassembler.a lib/libLLVMX86Info.a lib/libLLVMX86Utils.a lib/libLLVMARMCodeGen.a lib/libLLVMARMAsmParser.a lib/libLLVMARMDesc.a lib/libLLVMARMDisassembler.a lib/libLLVMARMInfo.a lib/libLLVMARMUtils.a lib/libLLVMAArch64CodeGen.a lib/libLLVMAArch64AsmParser.a lib/libLLVMAArch64Desc.a lib/libLLVMAArch64Disassembler.a lib/libLLVMAArch64Info.a lib/libLLVMAArch64Utils.a lib/libLLVMRISCVCodeGen.a lib/libLLVMRISCVAsmParser.a lib/libLLVMRISCVDesc.a lib/libLLVMRISCVDisassembler.a lib/libLLVMRISCVInfo.a lib/libLLVMRISCVUtils.a lib/libLLVMAnalysis.a lib/libLLVMCodeGen.a lib/libLLVMCore.a lib/libLLVMipo.a lib/libLLVMAggressiveInstCombine.a lib/libLLVMInstCombine.a lib/libLLVMInstrumentation.a lib/libLLVMMC.a lib/libLLVMMCParser.a lib/libLLVMObjCARCOpts.a lib/libLLVMOption.a lib/libLLVMScalarOpts.a lib/libLLVMSupport.a lib/libLLVMTransformUtils.a lib/libLLVMVectorize.a -lpthread lib/libclangBasic.a lib/libclangCodeGen.a lib/libclangDriver.a lib/libclangFrontend.a lib/libclangFrontendTool.a lib/libclangSerialization.a lib/libLLVMARMDesc.a lib/libLLVMARMInfo.a lib/libLLVMARMUtils.a lib/libLLVMCFGuard.a lib/libLLVMAArch64Desc.a lib/libLLVMAArch64Info.a lib/libLLVMAArch64Utils.a lib/libLLVMAsmPrinter.a lib/libLLVMDebugInfoDWARF.a lib/libLLVMGlobalISel.a lib/libLLVMSelectionDAG.a lib/libLLVMMCDisassembler.a lib/libclangCodeGen.a lib/libLLVMCoverage.a lib/libLLVMLTO.a lib/libLLVMObjCARCOpts.a lib/libLLVMPasses.a lib/libLLVMCodeGen.a lib/libLLVMTarget.a lib/libLLVMCoroutines.a lib/libLLVMipo.a lib/libLLVMInstrumentation.a lib/libLLVMVectorize.a lib/libLLVMBitWriter.a lib/libLLVMIRReader.a lib/libLLVMAsmParser.a lib/libLLVMLinker.a lib/libLLVMScalarOpts.a lib/libLLVMAggressiveInstCombine.a lib/libLLVMInstCombine.a lib/libclangRewriteFrontend.a lib/libclangStaticAnalyzerFrontend.a lib/libclangStaticAnalyzerCheckers.a lib/libclangStaticAnalyzerCore.a lib/libclangCrossTU.a lib/libclangIndex.a lib/libclangFrontend.a lib/libclangDriver.a lib/libLLVMOption.a lib/libclangParse.a lib/libclangSerialization.a lib/libclangSema.a lib/libclangAnalysis.a lib/libclangASTMatchers.a lib/libclangEdit.a lib/libclangFormat.a lib/libclangToolingInclusions.a lib/libclangToolingCore.a lib/libclangAST.a lib/libLLVMFrontendOpenMP.a lib/libLLVMTransformUtils.a lib/libLLVMAnalysis.a lib/libLLVMProfileData.a lib/libLLVMObject.a lib/libLLVMMCParser.a lib/libLLVMBitReader.a lib/libLLVMTextAPI.a lib/libclangRewrite.a lib/libclangLex.a lib/libclangBasic.a lib/libLLVMCore.a lib/libLLVMRemarks.a lib/libLLVMBitstreamReader.a lib/libLLVMMC.a lib/libLLVMBinaryFormat.a lib/libLLVMDebugInfoCodeView.a lib/libLLVMDebugInfoMSF.a lib/libLLVMSupport.a -lrt -ldl -lpthread -lm lib/libLLVMDemangle.a && :
ld.lld: error: undefined symbol: llvm::setBugReportMsg(char const*)
>>> referenced by driver.cpp
>>>               tools/clang/tools/driver/CMakeFiles/clang.dir/driver.cpp.o:(main)

Would you mind taking a look? Thanks.

Builder: https://luci-milo.appspot.com/p/fuchsia/builders/ci/clang-linux-x64/b8884769398556395840

[probinson]

Hi @leonardchan
Owen is on UK time so I took a look. I think Owen inadvertently put the new API in a place that is guarded by #if ENABLE_BACKTRACES and I'm guessing that your build has that turned off.
I've posted D76893 because something has gone wrong with my git environment and I can't commit it myself right now.
I didn't actually try a build with backtraces off, because I figured you'd rather have the likely fix sooner. Hope I did fix it and sorry for the breakage.

clang/lib/Driver/Driver.cpp

void Driver::generateCompilationDiagnostics(
   // Don't try to generate diagnostics for link or dsymutil jobs.
   if (FailingCommand.getCreator().isLinkJob() ||
       FailingCommand.getCreator().isDsymutilJob())
     return;
 
   // Print the version of the compiler.
   PrintVersion(C, llvm::errs());
 
-  Diag(clang::diag::note_drv_command_failed_diag_msg)
-      << "PLEASE submit a bug report to " BUG_REPORT_URL " and include the "
-         "crash backtrace, preprocessed source, and associated run script.";
-
   // Suppress driver output and emit preprocessor output to temp file.
   Mode = CPPMode;
   CCGenDiagnostics = true;
 
   // Save the original job command(s).
   Command Cmd = FailingCommand;
 
   // Keep track of whether we produce any errors while trying to produce

clang/tools/driver/driver.cpp

 #include "llvm/Support/BuryPointer.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/CrashRecoveryContext.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/StringSaver.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
static int ExecuteCC1Tool(SmallVectorImpl<const char *> &ArgV) {
   llvm::errs() << "error: unknown integrated tool '" << Tool << "'. "
                << "Valid tools include '-cc1' and '-cc1as'.\n";
   return 1;
 }
 
 int main(int argc_, const char **argv_) {
   noteBottomOfStack();
   llvm::InitLLVM X(argc_, argv_);
+  llvm::setBugReportMsg("PLEASE submit a bug report to " BUG_REPORT_URL
+                        " and include the crash backtrace, preprocessed "
+                        "source, and associated run script.\n");
   SmallVector<const char *, 256> argv(argv_, argv_ + argc_);
 
   if (llvm::sys::Process::FixupStandardFileDescriptors())
     return 1;
 
   llvm::InitializeAllTargets();
   auto TargetAndMode = ToolChain::getTargetAndModeFromProgramName(argv[0]);
 

llvm/include/llvm/Support/PrettyStackTrace.h

namespace llvm {
   /// This is a per-thread decision so that a program can choose to print stack
   /// traces only on a primary thread, or on all threads that use
   /// PrettyStackTraceEntry.
   ///
   /// \see EnablePrettyStackTrace
   /// \see PrettyStackTraceEntry
   void EnablePrettyStackTraceOnSigInfoForThisThread(bool ShouldEnable = true);
 
+  /// Replaces the generic bug report message that is output upon
+  /// a crash.
+  void setBugReportMsg(const char *Msg);
+
   /// PrettyStackTraceEntry - This class is used to represent a frame of the
   /// "pretty" stack trace that is dumped when a program crashes. You can define
   /// subclasses of this and declare them on the program stack: when they are
   /// constructed and destructed, they will add their symbolic frames to a
   /// virtual stack trace.  This gets dumped out if the program crashes.
   class PrettyStackTraceEntry {
     friend PrettyStackTraceEntry *ReverseStackTrace(PrettyStackTraceEntry *);
 

llvm/lib/Support/PrettyStackTrace.cpp

 #ifdef __APPLE__
 using CrashHandlerString = SmallString<2048>;
 using CrashHandlerStringStorage =
     std::aligned_storage<sizeof(CrashHandlerString),
                          alignof(CrashHandlerString)>::type;
 static CrashHandlerStringStorage crashHandlerStringStorage;
 #endif
 
+static const char *BugReportMsg =
+    "PLEASE submit a bug report to " BUG_REPORT_URL
+    " and include the crash backtrace.\n";
+
+void llvm::setBugReportMsg(const char *Msg) { BugReportMsg = Msg; }
+
 /// This callback is run if a fatal signal is delivered to the process, it
 /// prints the pretty stack trace.
 static void CrashHandler(void *) {
+  errs() << BugReportMsg ;
+
 #ifndef __APPLE__
   // On non-apple systems, just emit the crash stack trace to stderr.
   PrintCurStackTrace(errs());
 #else
   // Emit the crash stack trace to a SmallString, put it where the system crash
   // handling will find it, and also send it to stderr.
   //
   // The SmallString is fairly large in the hope that we don't allocate (we're
   // handling a fatal signal, something is already pretty wrong, allocation
   // might not work). Further, we don't use a magic static in case that's also
   // borked. We leak any allocation that does occur because the program is about