[llvm-objdump] Create ObjectFile specific dumpers

We pay the one-off boilerplate overhead to create `*Dumper` classes that derive
from objdump::Dumper a la llvm-readobj. This has two primary advantages.

First, a lot object file format specific code can be moved from
llvm-objdump.cpp to *Dump.cpp files. Refactor `printPrivateHeaders` as
an example.

Second, with the introduction of ELFDumper<ELFT>, we can simplify
a few dispatch functions in ELFDump.cpp.

In addition, the ObjectFile specific dumpers contains a ObjectFile specific
reference so that we can remove a lot of `cast<*ObjectFile>(Obj)`.

Reviewed By: mtrofin

Differential Revision: https://reviews.llvm.org/D155045

1 files changed, 26 insertions, 20 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 052b7f1..4d2e59d 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -256,6 +256,22 @@ void Dumper::reportUniqueWarning(const Twine &Msg) {
     reportWarning(Msg, O.getFileName());
 }
 
+static Expected<std::unique_ptr<Dumper>> createDumper(const ObjectFile &Obj) {
+  if (const auto *O = dyn_cast<COFFObjectFile>(&Obj))
+    return createCOFFDumper(*O);
+  if (const auto *O = dyn_cast<ELFObjectFileBase>(&Obj))
+    return createELFDumper(*O);
+  if (const auto *O = dyn_cast<MachOObjectFile>(&Obj))
+    return createMachODumper(*O);
+  if (const auto *O = dyn_cast<WasmObjectFile>(&Obj))
+    return createWasmDumper(*O);
+  if (const auto *O = dyn_cast<XCOFFObjectFile>(&Obj))
+    return createXCOFFDumper(*O);
+
+  return createStringError(errc::invalid_argument,
+                           "unsupported object file format");
+}
+
 namespace {
 struct FilterResult {
   // True if the section should not be skipped.
@@ -2697,24 +2713,8 @@ static void printFaultMaps(const ObjectFile *Obj) {
   outs() << FMP;
 }
 
-static void printPrivateFileHeaders(const ObjectFile *O, bool OnlyFirst) {
-  if (O->isELF()) {
-    printELFFileHeader(O);
-    printELFDynamicSection(O);
-    printELFSymbolVersionInfo(O);
-    return;
-  }
-  if (O->isCOFF())
-    return printCOFFFileHeader(cast<object::COFFObjectFile>(*O));
-  if (O->isWasm())
-    return printWasmFileHeader(O);
-  if (O->isMachO()) {
-    printMachOFileHeader(O);
-    if (!OnlyFirst)
-      printMachOLoadCommands(O);
-    return;
-  }
-  reportError(O->getFileName(), "Invalid/Unsupported object file format");
+void Dumper::printPrivateHeaders(bool) {
+  reportError(O.getFileName(), "Invalid/Unsupported object file format");
 }
 
 static void printFileHeaders(const ObjectFile *O) {
@@ -2817,7 +2817,13 @@ static void checkForInvalidStartStopAddress(ObjectFile *Obj,
 
 static void dumpObject(ObjectFile *O, const Archive *A = nullptr,
                        const Archive::Child *C = nullptr) {
-  Dumper D(*O);
+  Expected<std::unique_ptr<Dumper>> DumperOrErr = createDumper(*O);
+  if (!DumperOrErr) {
+    reportError(DumperOrErr.takeError(), O->getFileName(),
+                A ? A->getFileName() : "");
+    return;
+  }
+  Dumper &D = **DumperOrErr;
 
   // Avoid other output when using a raw option.
   if (!RawClangAST) {
@@ -2842,7 +2848,7 @@ static void dumpObject(ObjectFile *O, const Archive *A = nullptr,
   if (FileHeaders)
     printFileHeaders(O);
   if (PrivateHeaders || FirstPrivateHeader)
-    printPrivateFileHeaders(O, FirstPrivateHeader);
+    D.printPrivateHeaders(FirstPrivateHeader);
   if (SectionHeaders)
     printSectionHeaders(*O);
   if (SymbolTable)