Object: Add support for bigobj

This adds support for reading the "bigobj" variant of COFF produced by
cl's /bigobj and mingw's -mbig-obj.

The most significant difference that bigobj brings is more than 2**16
sections to COFF.

bigobj brings a few interesting differences with it:
- It doesn't have a Characteristics field in the file header.
- It doesn't have a SizeOfOptionalHeader field in the file header (it's
  only used in executable files).
- Auxiliary symbol records have the same width as a symbol table entry.
  Since symbol table entries are bigger, so are auxiliary symbol
  records.

Write support will come soon.

Differential Revision: http://reviews.llvm.org/D5259

llvm-svn: 217496

1 files changed, 2 insertions, 9 deletions

diff --git a/llvm/tools/llvm-objdump/COFFDump.cpp b/llvm/tools/llvm-objdump/COFFDump.cpp
index 39d8e8e39f8..818969114ba 100644
--- a/llvm/tools/llvm-objdump/COFFDump.cpp
+++ b/llvm/tools/llvm-objdump/COFFDump.cpp
@@ -260,11 +260,8 @@ static void printLoadConfiguration(const COFFObjectFile *Obj) {
   if (!PE32Header)
     return;
 
-  const coff_file_header *Header;
-  if (error(Obj->getCOFFHeader(Header)))
-    return;
   // Currently only x86 is supported
-  if (Header->Machine != COFF::IMAGE_FILE_MACHINE_I386)
+  if (Obj->getMachine() != COFF::IMAGE_FILE_MACHINE_I386)
     return;
 
   const data_directory *DataDir;
@@ -518,11 +515,7 @@ static void printRuntimeFunctionRels(const COFFObjectFile *Obj,
 }
 
 void llvm::printCOFFUnwindInfo(const COFFObjectFile *Obj) {
-  const coff_file_header *Header;
-  if (error(Obj->getCOFFHeader(Header)))
-    return;
-
-  if (Header->Machine != COFF::IMAGE_FILE_MACHINE_AMD64) {
+  if (Obj->getMachine() != COFF::IMAGE_FILE_MACHINE_AMD64) {
     errs() << "Unsupported image machine type "
               "(currently only AMD64 is supported).\n";
     return;