COFF: Fix short import lib import name type bitshift

[martell]

Summary

llvm-readobj: Support short import objects from within an archive
The import magic was previous just checked against the archive as a whole

As per the PE COFF spec (section 8.3, Import Name Type)
Offset: 18 Size 2 bits Name: Type
Offset: 20 Size 3 bits Name: Name Type

Offset: 20 added based on 18+2

[majnemer]

llvm-readobj reads this field. perhaps we could have a testcase?

[martell]

In D23540#516191, @majnemer wrote:

llvm-readobj reads this field. perhaps we could have a testcase?

lld also uses it to determine stripping of the symbol names.
This is mostly why i686 was broken at link time

I will add a test case

[compnerd]

Please add a test case for llvm via llvm-readobj.

[martell]

llvm-readobj hello.lib

File: HELLO.dll
Format: COFF-x86-64
Arch: x86_64
AddressSize: 64bit

File: HELLO.dll
Format: COFF-x86-64
Arch: x86_64
AddressSize: 64bit

File: HELLO.dll
Format: COFF-x86-64
Arch: x86_64
AddressSize: 64bit

Error reading file: hello.lib: Unrecognized file type..

It seems that objdump does not know how to handle short import sections.
Are you sure it is being used?

[compnerd]

Yeah, it should be:

if (COFFImportFile *Import = dyn_cast<COFFImportFile>(&Binary))
  dumpCOFFImportFile(Import);

llvm/trunk/include/llvm/Support/COFF.h

struct ImportHeader {
     uint16_t OrdinalHint;
     uint16_t TypeInfo;
 
     ImportType getType() const {
       return static_cast<ImportType>(TypeInfo & 0x3);
     }
 
     ImportNameType getNameType() const {
-      return static_cast<ImportNameType>((TypeInfo & 0x1C) >> 3);
+      return static_cast<ImportNameType>((TypeInfo & 0x1C) >> 2);
     }
   };
 
   enum CodeViewIdentifiers {
     DEBUG_SECTION_MAGIC = 0x4,
   };
 
   inline bool isReservedSectionNumber(int32_t SectionNumber) {
     return SectionNumber <= 0;
   }
 
 } // End namespace COFF.
 } // End namespace llvm.
 
 #endif

llvm/trunk/test/tools/llvm-readobj/coff-exports-implib.test

 RUN: llvm-readobj -coff-exports %p/Inputs/library.lib | FileCheck %s
 
 CHECK: File: library.dll
 CHECK: Format: COFF-import-file
 CHECK: Type: const
+CHECK: Name type: undecorate
 CHECK: Symbol: __imp__constant
 
 CHECK: File: library.dll
 CHECK: Format: COFF-import-file
 CHECK: Type: data
+CHECK: Name type: noprefix
 CHECK: Symbol: __imp__data
 
 CHECK: File: library.dll
 CHECK: Format: COFF-import-file
 CHECK: Type: code
+CHECK: Name type: name
 CHECK: Symbol: __imp__function
 
 CHECK: File: library.dll
 CHECK: Format: COFF-import-file
 CHECK: Type: code
+CHECK: Name type: ordinal
 CHECK: Symbol: __imp__ordinal