llvm-dwarfdump: Add support for -debug-info=<offset>.

This is the first of many commits that enable selectively dumping just
one record from the debug info.

This reapplies r313412 with some extra qualification to appease GCC and MSVC.

llvm-svn: 313419

1 files changed, 77 insertions, 10 deletions

diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index 823eb8e8133..0ac3354a7aa 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -37,8 +37,63 @@
 using namespace llvm;
 using namespace object;
 
+/// Parser for options that take an optional offest argument.
+/// @{
+struct OffsetOption {
+  uint64_t Val = 0;
+  bool HasValue = false;
+  bool IsRequested = false;
+};
+
+namespace llvm {
+namespace cl {
+template <>
+class parser<OffsetOption> final : public basic_parser<OffsetOption> {
+public:
+  parser(Option &O) : basic_parser(O) {}
+
+  /// Return true on error.
+  bool parse(Option &O, StringRef ArgName, StringRef Arg, OffsetOption &Val) {
+    if (Arg == "") {
+      Val.Val = 0;
+      Val.HasValue = false;
+      Val.IsRequested = true;
+      return false;
+    }
+    if (Arg.getAsInteger(0, Val.Val))
+      return O.error("'" + Arg + "' value invalid for integer argument!");
+    Val.HasValue = true;
+    Val.IsRequested = true;
+    return false;
+  }
+
+  enum ValueExpected getValueExpectedFlagDefault() const {
+    return ValueOptional;
+  }
+
+  void printOptionInfo(const Option &O, size_t GlobalWidth) const {
+    outs() << "  -" << O.ArgStr;
+    Option::printHelpStr(O.HelpStr, GlobalWidth, getOptionWidth(O));
+  }
+
+  void printOptionDiff(const Option &O, OffsetOption V, OptVal Default,
+                       size_t GlobalWidth) const {
+    printOptionName(O, GlobalWidth);
+    outs() << "[=offset]";
+  }
+
+  // An out-of-line virtual method to provide a 'home' for this class.
+  void anchor() override {};
+};
+} // cl
+} // llvm
+
+/// @}
+/// Command line options.
+/// @{
+
 namespace {
-using namespace llvm::cl;
+using namespace cl;
 
 OptionCategory DwarfDumpCategory("Specific Options");
 static opt<bool> Help("h", desc("Alias for -help"), Hidden,
@@ -47,20 +102,26 @@ static list<std::string>
     InputFilenames(Positional, desc("<input object files or .dSYM bundles>"),
                    ZeroOrMore, cat(DwarfDumpCategory));
 
-cl::OptionCategory
-    SectionCategory("Section-specific Dump Options",
-                    "These control which sections are dumped.");
+cl::OptionCategory SectionCategory("Section-specific Dump Options",
+                                   "These control which sections are dumped. "
+                                   "Where applicable these parameters take an "
+                                   "optional =<offset> argument to dump only "
+                                   "the entry at the specified offset.");
+
 static opt<bool> DumpAll("all", desc("Dump all debug info sections"),
                          cat(SectionCategory));
 static alias DumpAllAlias("a", desc("Alias for -all"), aliasopt(DumpAll));
 
+// Options for dumping specific sections.
 static unsigned DumpType = DIDT_Null;
+static std::array<llvm::Optional<uint64_t>, (unsigned)DIDT_ID_Count> DumpOffsets;
 #define HANDLE_DWARF_SECTION(ENUM_NAME, ELF_NAME, CMDLINE_NAME)                \
-  static opt<bool> Dump##ENUM_NAME(CMDLINE_NAME,                               \
-                                   desc("Dump the " ELF_NAME " section"),      \
-                                   cat(SectionCategory));
+  static opt<OffsetOption> Dump##ENUM_NAME(                                    \
+      CMDLINE_NAME, desc("Dump the " ELF_NAME " section"),                     \
+      cat(SectionCategory));
 #include "llvm/BinaryFormat/Dwarf.def"
 #undef HANDLE_DWARF_SECTION
+
 static opt<bool> DumpUUID("uuid", desc("Show the UUID for each architecture"),
                           cat(DwarfDumpCategory));
 static alias DumpUUIDAlias("u", desc("Alias for -uuid"), aliasopt(DumpUUID));
@@ -78,6 +139,9 @@ static opt<bool> Verbose("verbose",
 static alias VerboseAlias("v", desc("Alias for -verbose"), aliasopt(Verbose),
                           cat(DwarfDumpCategory));
 } // namespace
+/// @}
+//===----------------------------------------------------------------------===//
+
 
 static void error(StringRef Filename, std::error_code EC) {
   if (!EC)
@@ -103,7 +167,7 @@ static bool dumpObjectFile(ObjectFile &Obj, Twine Filename) {
     outs() << Filename << ":\tfile format " << Obj.getFileFormatName() << '\n';
 
   // Dump the complete DWARF structure.
-  DICtx->dump(outs(), getDumpOpts());
+  DICtx->dump(outs(), getDumpOpts(), DumpOffsets);
   return true;
 }
 
@@ -237,8 +301,11 @@ int main(int argc, char **argv) {
   // Defaults to dumping all sections, unless brief mode is specified in which
   // case only the .debug_info section in dumped.
 #define HANDLE_DWARF_SECTION(ENUM_NAME, ELF_NAME, CMDLINE_NAME)                \
-  if (Dump##ENUM_NAME)                                                         \
-    DumpType |= DIDT_##ENUM_NAME;
+  if (Dump##ENUM_NAME.IsRequested) {                                           \
+    DumpType |= DIDT_##ENUM_NAME;                                              \
+    if (Dump##ENUM_NAME.HasValue)                                              \
+      DumpOffsets[DIDT_ID_##ENUM_NAME] = Dump##ENUM_NAME.Val;                  \
+  }
 #include "llvm/BinaryFormat/Dwarf.def"
 #undef HANDLE_DWARF_SECTION
   if (DumpUUID)