[COFF] ARM64 support for COFFImportFile

[mstorsjo]

Summary

Tested that a DLL+implib created with LLD seems to load properly. What would be a suitable location for a testcase for this? Some sort of higher level test in LLD?

[compnerd]

You should be able to generate an object file with the imgrel relocation.

[mstorsjo]

In D35766#818234, @compnerd wrote:

You should be able to generate an object file with the imgrel relocation.

That doesn't actually test this codepath, that's already handled within lib/Target/AArch64/MCTargetDesc/AArch64WinCOFFObjectWriter.cpp, where VK_COFF_IMGREL32 is mapped to COFF::IMAGE_REL_ARM64_ADDR32NB. The only place where this getImgRelRelocation function is used is within COFFImportFile.cpp, in the createImportDescriptor function.

[ruiu]

Can you add a test?

[mstorsjo]

In D35766#819125, @ruiu wrote:

Can you add a test?

Yes, I'd like to. In the original comment, I asked for suggestions on where/how to add such a test. Are there any tool entry points within llvm that actually use this functionality? Maybe llvm-dlltool; are there any other? It'd be easy to test this from within lld though.

[ruiu]

The file used to be part of lld, so I think this is tested by some test file in lld. Can you add a new test if there's such file?

[mstorsjo]

Created a test for this, for the lld repo, in D35814.

[ruiu]

LGTM

lib/Object/COFFImportFile.cpp

 
 namespace llvm {
 namespace object {
 
 static bool is32bit(MachineTypes Machine) {
   switch (Machine) {
   default:
     llvm_unreachable("unsupported machine");
+  case IMAGE_FILE_MACHINE_ARM64:
   case IMAGE_FILE_MACHINE_AMD64:
     return false;
   case IMAGE_FILE_MACHINE_ARMNT:
   case IMAGE_FILE_MACHINE_I386:
     return true;
   }
 }
 
 static uint16_t getImgRelRelocation(MachineTypes Machine) {
   switch (Machine) {
   default:
     llvm_unreachable("unsupported machine");
   case IMAGE_FILE_MACHINE_AMD64:
     return IMAGE_REL_AMD64_ADDR32NB;
   case IMAGE_FILE_MACHINE_ARMNT:
     return IMAGE_REL_ARM_ADDR32NB;
+  case IMAGE_FILE_MACHINE_ARM64:
+    return IMAGE_REL_ARM64_ADDR32NB;
   case IMAGE_FILE_MACHINE_I386:
     return IMAGE_REL_I386_DIR32NB;
   }
 }
 
 template <class T> static void append(std::vector<uint8_t> &B, const T &Data) {
   size_t S = B.size();
   B.resize(S + sizeof(T));