Demonstrating lack of thread-safety in BackendUtil

[teemperor]

Summary

Do not merge, this is just a demo patch.

Build with LLDB in the enabled LLVM projects and then run ninja SymbolTests ; ./tools/lldb/unittests/Symbol/SymbolTests --gtest_filter="*Fuzz*"

[teemperor]

Not a real review, just dumping code here.

[dblaikie]

I think there's a way to post a Phab 'reivew' that won't send mail to the -commits lists, but I forget what it is. I thought it might've been some metadata tag, but can't find it (maybe @MaskRay or @mehdi_amini recall what the magic was)

[MaskRay]

arc diff 'HEAD^' --draft creates a draft Diff which triggers pre-commit bots but does not trigger llvm-commits, IIRC.

[teemperor]

Sorry, my bad, I thought if I won't specify any repo/project in Phabricator it won't trigger the Herald (I was using the web interface, not arcanist).

[dblaikie]

In D99650#2671915, @MaskRay wrote:

arc diff 'HEAD^' --draft creates a draft Diff which triggers pre-commit bots but does not trigger llvm-commits, IIRC.

Do you know if there's a way to access this functionality when creating the review via the web UI rather than via arc?

[MaskRay]

In D99650#2699120, @dblaikie wrote:

In D99650#2671915, @MaskRay wrote:

arc diff 'HEAD^' --draft creates a draft Diff which triggers pre-commit bots but does not trigger llvm-commits, IIRC.

Do you know if there's a way to access this functionality when creating the review via the web UI rather than via arc?

I am not clear. https://reviews.llvm.org/differential/diff/create/ with "Visible To" set to "No One" might work, but I haven't created differentials with the web UI...

lldb/unittests/Symbol/TestTypeSystemClang.cpp

 //===-- TestTypeSystemClang.cpp -------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "Plugins/ExpressionParser/Clang/ClangUtil.h"
 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
 #include "TestingSupport/SubsystemRAII.h"
 #include "TestingSupport/Symbol/ClangTestUtils.h"
 #include "lldb/Host/FileSystem.h"
 #include "lldb/Host/HostInfo.h"
 #include "lldb/Symbol/Declaration.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/ExprCXX.h"
 #include "gtest/gtest.h"
+#include "clang/Lex/HeaderSearchOptions.h"
+#include "clang/CodeGen/BackendUtil.h"
+#include "llvm/Support/ThreadPool.h"
 
 using namespace clang;
 using namespace lldb;
 using namespace lldb_private;
 
 class TestTypeSystemClang : public testing::Test {
 public:
   SubsystemRAII<FileSystem, HostInfo> subsystems;
EXPECT_EQ(
       ScratchTypeSystemClang::DefaultAST,
       ScratchTypeSystemClang::InferIsolatedASTKindFromLangOpts(lang_opts));
 
   lang_opts.Modules = true;
   EXPECT_EQ(
       ScratchTypeSystemClang::IsolatedASTKind::CppModules,
       ScratchTypeSystemClang::InferIsolatedASTKindFromLangOpts(lang_opts));
 }
+
+
+TEST_F(TestTypeSystemClang, FuzzClangBackend) {
+  llvm::ThreadPoolStrategy s;
+  s.ThreadsRequested = 4000;
+  llvm::ThreadPool Pool(s);
+  for (size_t i = 0; i < s.ThreadsRequested; ++i) {
+    Pool.async([this, i] {
+        clang::CodeGenOptions cgopts;
+        clang::HeaderSearchOptions hs;
+        clang::TargetOptions topts;
+        llvm::LLVMContext ctx;
+        llvm::Module m("foo", ctx);
+        auto os = std::make_unique<llvm::raw_null_ostream>();
+        clang::EmitBackendOutput(m_ast->getASTContext().getDiagnostics(), hs, cgopts,
+                                 topts, *m_ast->GetLangOpts(),
+                                 m_ast->getASTContext().getTargetInfo().getDataLayout(),
+                                 &m, Backend_EmitNothing, std::move(os));
+    });
+  }
+  Pool.wait();
+}

llvm/lib/Support/CommandLine.cpp

 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/StringSaver.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstdlib>
 #include <map>
 #include <string>
+#include <unistd.h>
 using namespace llvm;
 using namespace cl;
 
 #define DEBUG_TYPE "commandline"
 
 //===----------------------------------------------------------------------===//
 // Template instantiations and anchors.
 //
else {
       for (auto *SC : Opt.Subs)
         addLiteralOption(Opt, SC, Name);
     }
   }
 
   void addOption(Option *O, SubCommand *SC) {
     bool HadErrors = false;
     if (O->hasArgStr()) {
+      if (O->ArgStr == "h")
+        llvm::errs() << (void*)SC << "\n";
       // If it's a DefaultOption, check to make sure it isn't already there.
       if (O->isDefaultOption() &&
           SC->OptionsMap.find(O->ArgStr) != SC->OptionsMap.end())
         return;
+      usleep(rand() % 20);
 
       // Add argument to the argument map!
+      llvm::errs() << "Inserting " << O->ArgStr << "\n";
       if (!SC->OptionsMap.insert(std::make_pair(O->ArgStr, O)).second) {
         errs() << ProgramName << ": CommandLine Error: Option '" << O->ArgStr
                << "' registered more than once!\n";
         HadErrors = true;
       }
     }
 
     // Remember information about positional options.
     if (O->getFormattingFlag() == cl::Positional)
       SC->PositionalOpts.push_back(O);
     else if (O->getMiscFlags() & cl::Sink) // Remember sink options
       SC->SinkOpts.push_back(O);
     else if (O->getNumOccurrencesFlag() == cl::ConsumeAfter) {
       if (SC->ConsumeAfterOpt) {
         O->error("Cannot specify more than one option with cl::ConsumeAfter!");
         HadErrors = true;
       }
       SC->ConsumeAfterOpt = O;
     }
 
     // Fail hard if there were errors. These are strictly unrecoverable and
     // indicate serious issues such as conflicting option names or an
     // incorrectly
     // linked LLVM distribution.
-    if (HadErrors)
+    if (HadErrors) {
+      abort();
       report_fatal_error("inconsistency in registered CommandLine options");
+    }
 
     // If we're adding this to all sub-commands, add it to the ones that have
     // already been registered.
     if (SC == &*AllSubCommands) {
       for (auto *Sub : RegisteredSubCommands) {
         if (SC == Sub)
           continue;
         addOption(O, Sub);

llvm/utils/unittest/UnitTestMain/TestMain.cpp

 
 int main(int argc, char **argv) {
   llvm::sys::PrintStackTraceOnErrorSignal(argv[0],
                                           true /* Disable crash reporting */);
 
   // Initialize both gmock and gtest.
   testing::InitGoogleMock(&argc, argv);
 
-  llvm::cl::ParseCommandLineOptions(argc, argv);
+  //llvm::cl::ParseCommandLineOptions(argc, argv);
 
   // Make it easy for a test to re-execute itself by saving argv[0].
   TestMainArgv0 = argv[0];
 
 # if defined(_WIN32)
   // Disable all of the possible ways Windows conspires to make automated
   // testing impossible.
   ::SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX);