[lld-macho] Support larger dylib symbol ordinals in bindings

[int3]

Summary

Do folks care if we don't have a test for this? Creating 16
dylibs to trigger this straightforward code path seems a little tedious

[smeenai]

I'm not super opposed to not having a test. It doesn't seem too terrible to write one though, just repetitive: we could produce 15 dylibs from the same source file and just have the 16th be different (to confirm the binding), right?

[int3]

we could produce 15 dylibs from the same source file and just have the 16th be different (to confirm the binding), right?

yeah pretty much. It's just annoying that FileCheck doesn't provide a better way of testing things like this

[smeenai]

In D85467#2203171, @int3 wrote:

we could produce 15 dylibs from the same source file and just have the 16th be different (to confirm the binding), right?

yeah pretty much. It's just annoying that FileCheck doesn't provide a better way of testing things like this

Agreed.

I'd prefer to still add the test, but LGTM either way.

lld/MachO/SyntheticSections.cpp

if (lastBinding.segment != seg) {
     lastBinding.offset = offset;
   }
 
   if (lastBinding.ordinal != dysym.file->ordinal) {
     if (dysym.file->ordinal <= BIND_IMMEDIATE_MASK) {
       os << static_cast<uint8_t>(BIND_OPCODE_SET_DYLIB_ORDINAL_IMM |
                                  dysym.file->ordinal);
     } else {
-      error("TODO: Support larger dylib symbol ordinals");
-      return;
+      os << static_cast<uint8_t>(MachO::BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB);
+      encodeULEB128(dysym.file->ordinal, os);
     }
     lastBinding.ordinal = dysym.file->ordinal;
   }
 
   if (lastBinding.addend != addend) {
     os << static_cast<uint8_t>(BIND_OPCODE_SET_ADDEND_SLEB);
     encodeSLEB128(addend, os);
     lastBinding.addend = addend;

 uint32_t LazyBindingSection::encode(const DylibSymbol &sym) {
   uint32_t opstreamOffset = contents.size();
   OutputSegment *dataSeg = in.lazyPointers->parent;
   os << static_cast<uint8_t>(MachO::BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB |
                              dataSeg->index);
   uint64_t offset = in.lazyPointers->addr - dataSeg->firstSection()->addr +
                     sym.stubsIndex * WordSize;
   encodeULEB128(offset, os);
-  if (sym.file->ordinal <= MachO::BIND_IMMEDIATE_MASK)
+  if (sym.file->ordinal <= MachO::BIND_IMMEDIATE_MASK) {
     os << static_cast<uint8_t>(MachO::BIND_OPCODE_SET_DYLIB_ORDINAL_IMM |
                                sym.file->ordinal);
-  else
-    fatal("TODO: Support larger dylib symbol ordinals");
+  } else {
+    os << static_cast<uint8_t>(MachO::BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB);
+    encodeULEB128(sym.file->ordinal, os);
+  }
 
   os << static_cast<uint8_t>(MachO::BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM)
      << sym.getName() << '\0'
      << static_cast<uint8_t>(MachO::BIND_OPCODE_DO_BIND)
      << static_cast<uint8_t>(MachO::BIND_OPCODE_DONE);
   return opstreamOffset;
 }