[RTDYLD] add debug statements for resolveX86Relocation

[vchuravy]

Summary

Adds some debug statements to resolveX86Relocation so that the next person doesn't have to diff the object to figure out what changed.

[vchuravy]

Fix typo

[MaskRay]

I think this can be very noisy as the number of relocations can be very large.

[vchuravy]

In D89211#2324122, @MaskRay wrote:

I think this can be very noisy as the number of relocations can be very large.

I agree. They can be rather noisy, but without them the only tool you have to debug relocations going wrong is to dump the section before and after relocations and to perform a manual diff,
and the code for x86_64 has the same debug statements for some relocations types as well. This kinda makes me wish we had multiple levels of debug output for LLVM, but let's not go there.

[lhames]

Sorry -- I missed this one earlier. For what it's worth JITLink prints with wild abandon. In general I'd rather log everything and then concentrate on log formatting to make it searchable/digestible.

llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

 
 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
                                           uint64_t Offset, uint32_t Value,
                                           uint32_t Type, int32_t Addend) {
   switch (Type) {
   case ELF::R_386_32: {
     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
         Value + Addend;
+    LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
+                      << format("%p\n", Section.getAddressWithOffset(Offset)));
     break;
   }
   // Handle R_386_PLT32 like R_386_PC32 since it should be able to
   // reach any 32 bit address.
   case ELF::R_386_PLT32:
   case ELF::R_386_PC32: {
     uint32_t FinalAddress =
         Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
     uint32_t RealOffset = Value + Addend - FinalAddress;
     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
         RealOffset;
+    LLVM_DEBUG(dbgs() << "Writing " << format("%p", RealOffset) << " at "
+                      << format("%p\n", Section.getAddressWithOffset(Offset)));
     break;
   }
   default:
     // There are other relocation types, but it appears these are the
     // only ones currently used by the LLVM ELF object writer
     report_fatal_error("Relocation type not implemented yet!");
     break;
   }