[Lldb-commits] [PATCH] D40745: Add a clang-ast subcommand to lldb-test

[Pavel Labath via lldb-commits]

The reason you hit the assert there, is because you're running lldb on
an un-linked object file. When you link the file, the linker will
resolve these relocations and they will disappear. This is also the
reason you got those errors after removing the assert  (you were
trying to parse unrelocated dwarf). To run your tests, you'll need to
run the object file through the linker (something like ld -shared -o
foo.so foo.o should suffice)

The fact that we crash there is certainly a bug, but the bug may be
that we are even accepting these files in the first place. It might be
interesting to make lldb read these files, if for nothing else, then
for the sake of testing, but that is not a trivial task. Right now
that relocating code is completely wrong (e.g. it assumes all
relocations are x86 relocations).

On 1 December 2017 at 20:49, Zachary Turner via Phabricator
<reviews at reviews.llvm.org> wrote:
> zturner created this revision.
> Herald added a subscriber: emaste.
>
> This is the bare minimum needed to dump `ClangASTContext`s via `lldb-test`.
>
> Within the first 10 seconds of using this, I already found a bug.  A `FIXME` note and repro is included in the comments in this patch.
>
> With this, it should be possible to do deep testing of otherwise difficult to test scenarios involving `ClangASTContext`.
>
>
> https://reviews.llvm.org/D40745
>
> Files:
>   lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
>   lldb/tools/lldb-test/lldb-test.cpp
>
>
> Index: lldb/tools/lldb-test/lldb-test.cpp
> ===================================================================
> --- lldb/tools/lldb-test/lldb-test.cpp
> +++ lldb/tools/lldb-test/lldb-test.cpp
> @@ -10,11 +10,15 @@
>  #include "FormatUtil.h"
>  #include "SystemInitializerTest.h"
>
> +#include "Plugins/SymbolFile/DWARF/SymbolFileDWARF.h"
>  #include "lldb/Core/Debugger.h"
>  #include "lldb/Core/Module.h"
>  #include "lldb/Core/Section.h"
>  #include "lldb/Initialization/SystemLifetimeManager.h"
> +#include "lldb/Symbol/ClangASTContext.h"
> +#include "lldb/Symbol/ClangASTImporter.h"
>  #include "lldb/Utility/DataExtractor.h"
> +#include "lldb/Utility/StreamString.h"
>
>  #include "llvm/ADT/StringRef.h"
>  #include "llvm/Support/CommandLine.h"
> @@ -30,26 +34,48 @@
>  namespace opts {
>  cl::SubCommand ModuleSubcommand("module-sections",
>                                  "Display LLDB Module Information");
> +cl::SubCommand ClangASTSubcommand("clang-ast", "Dump Clang AST for input file");
>
>  namespace module {
>  cl::opt<bool> SectionContents("contents",
>                                cl::desc("Dump each section's contents"),
>                                cl::sub(ModuleSubcommand));
>  cl::list<std::string> InputFilenames(cl::Positional, cl::desc("<input files>"),
>                                       cl::OneOrMore, cl::sub(ModuleSubcommand));
>  } // namespace module
> +
> +namespace clang_ast {
> +cl::list<std::string> InputFilenames(cl::Positional, cl::desc("<input files>"),
> +                                     cl::OneOrMore,
> +                                     cl::sub(ClangASTSubcommand));
> +}
>  } // namespace opts
>
>  static llvm::ManagedStatic<SystemLifetimeManager> DebuggerLifetime;
>
> +static void dumpClangASTContext(Debugger &Dbg) {
> +  for (const auto &File : opts::clang_ast::InputFilenames) {
> +    ModuleSpec Spec{FileSpec(File, false)};
> +    Spec.GetSymbolFileSpec().SetFile(File, false);
> +
> +    auto ModulePtr = std::make_shared<lldb_private::Module>(Spec);
> +
> +    StreamString Stream;
> +    ModulePtr->ParseAllDebugSymbols();
> +    ModulePtr->Dump(&Stream);
> +    llvm::outs() << Stream.GetData() << "\n";
> +    llvm::outs().flush();
> +  }
> +}
> +
>  static void dumpModules(Debugger &Dbg) {
>    LinePrinter Printer(4, llvm::outs());
>
>    for (const auto &File : opts::module::InputFilenames) {
>      ModuleSpec Spec{FileSpec(File, false)};
>      Spec.GetSymbolFileSpec().SetFile(File, false);
>
> -    auto ModulePtr = std::make_shared<Module>(Spec);
> +    auto ModulePtr = std::make_shared<lldb_private::Module>(Spec);
>      SectionList *Sections = ModulePtr->GetSectionList();
>      if (!Sections) {
>        llvm::errs() << "Could not load sections for module " << File << "\n";
> @@ -92,6 +118,8 @@
>
>    if (opts::ModuleSubcommand)
>      dumpModules(*Dbg);
> +  else if (opts::ClangASTSubcommand)
> +    dumpClangASTContext(*Dbg);
>
>    DebuggerLifetime->Terminate();
>    return 0;
> Index: lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
> ===================================================================
> --- lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
> +++ lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
> @@ -2764,6 +2764,14 @@
>        case R_386_32:
>        case R_386_PC32:
>        default:
> +        // FIXME: This asserts with this input:
> +        //
> +        // foo.cpp
> +        // int main(int argc, char **argv) { return 0; }
> +        //
> +        // clang++.exe --target=i686-unknown-linux-gnu -g -c foo.cpp -o foo.o
> +        //
> +        // and running this on the foo.o module.
>          assert(false && "unexpected relocation type");
>        }
>      } else {
>
>