llvm-objdump: Dump COFF import table if -private-headers option is given.

This is a patch to add capability to llvm-objdump to dump COFF Import Table
entries, so that we can write tests for LLD checking Import Table contents.

llvm-objdump did not print anything but just file name if the format is COFF
and -private-headers option is given. This is a patch adds capability for
dumping DLL Import Table, which is specific to the COFF format.

In this patch I defined a new iterator to iterate over import table entries.
Also added a few functions to COFFObjectFile.cpp to access fields of the entry.

Differential Revision: http://llvm-reviews.chandlerc.com/D1719

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191472 91177308-0d34-0410-b5e6-96231b3b80d8

tools/llvm-objdump/COFFDump.cpp

@@ -227,6 +227,48 @@ static void printCOFFSymbolAddress(llvm::raw_ostream &Out,
     Out << format(" + 0x%04x", Disp);
 }
 
+// Prints import tables. The import table is a table containing the list of
+// DLL name and symbol names which will be linked by the loader.
+static void printImportTables(const COFFObjectFile *Obj) {
+  outs() << "The Import Tables:\n";
+  error_code ec;
+  for (import_directory_iterator i = Obj->getImportDirectoryBegin(),
+                                 e = Obj->getImportDirectoryEnd();
+       i != e; i = i.increment(ec)) {
+    if (ec)
+      return;
+
+    const import_directory_table_entry *Dir;
+    StringRef Name;
+    if (i->getImportTableEntry(Dir)) return;
+    if (i->getName(Name)) return;
+
+    outs() << format("  lookup %08x", Dir->ImportLookupTableRVA);
+    outs() << format(" time %08x", Dir->TimeDateStamp);
+    outs() << format(" fwd %08x", Dir->ForwarderChain);
+    outs() << format(" name %08x", Dir->NameRVA);
+    outs() << format(" addr %08x\n\n", Dir->ImportAddressTableRVA);
+
+    outs() << "    DLL Name: " << Name << "\n";
+    outs() << "    Hint/Ord  Name\n";
+    const COFF::ImportLookupTableEntry32 *entry;
+    if (i->getImportLookupEntry(entry))
+      return;
+    for (; entry->data; ++entry) {
+      if (entry->isOrdinal()) {
+        outs() << format("      % 6d\n", entry->getOrdinal());
+        continue;
+      }
+      uint16_t Hint;
+      StringRef Name;
+      if (Obj->getHintName(entry->getHintNameRVA(), Hint, Name))
+        return;
+      outs() << format("      % 6d  %s\n", Hint, Name);
+    }
+    outs() << "\n";
+  }
+}
+
 void llvm::printCOFFUnwindInfo(const COFFObjectFile *Obj) {
   const coff_file_header *Header;
   if (error(Obj->getCOFFHeader(Header))) return;
@@ -353,3 +395,7 @@ void llvm::printCOFFUnwindInfo(const COFFObjectFile *Obj) {
     }
   }
 }
+
+void llvm::printCOFFFileHeader(const object::ObjectFile *Obj) {
+  printImportTables(dyn_cast<const COFFObjectFile>(Obj));
+}

tools/llvm-objdump/llvm-objdump.cpp

@@ -770,6 +770,14 @@ static void PrintUnwindInfo(const ObjectFile *o) {
   }
 }
 
+static void printPrivateFileHeader(const ObjectFile *o) {
+  if (o->isELF()) {
+    printELFFileHeader(o);
+  } else if (o->isCOFF()) {
+    printCOFFFileHeader(o);
+  }
+}
+
 static void DumpObject(const ObjectFile *o) {
   outs() << '\n';
   outs() << o->getFileName()
@@ -787,8 +795,8 @@ static void DumpObject(const ObjectFile *o) {
     PrintSymbolTable(o);
   if (UnwindInfo)
     PrintUnwindInfo(o);
-  if (PrivateHeaders && o->isELF())
-    printELFFileHeader(o);
+  if (PrivateHeaders)
+    printPrivateFileHeader(o);
 }
 
 /// @brief Dump each object file in \a a;

tools/llvm-objdump/llvm-objdump.h

@@ -34,7 +34,8 @@ void DumpBytes(StringRef bytes);
 void DisassembleInputMachO(StringRef Filename);
 void printCOFFUnwindInfo(const object::COFFObjectFile* o);
 void printELFFileHeader(const object::ObjectFile *o);
+void printCOFFFileHeader(const object::ObjectFile *o);
 
-}
+} // end namespace llvm
 
 #endif