[Object] Support LoongArch in RelocationResolver

[xen0n]

Summary

Similar to the RISCV logic added in D62062.

With this patch applied, llvm-dwarfdump works on existing LoongArch
object files, but generation of debuginfo on LoongArch is still pending
on proper support for relocations, so no test cases this time. They will
come later.

[xen0n]

rebase and simplify code

[wangleiat]

LGTM

llvm/lib/Object/RelocationResolver.cpp

case ELF::R_CKCORE_ADDR32:
     return (S + Addend) & 0xFFFFFFFF;
   case ELF::R_CKCORE_PCREL32:
     return (S + Addend - Offset) & 0xFFFFFFFF;
   default:
     llvm_unreachable("Invalid relocation type");
   }
 }
 
+static bool supportsLoongArch(uint64_t Type) {
+  switch (Type) {
+  case ELF::R_LARCH_NONE:
+  case ELF::R_LARCH_32:
+  case ELF::R_LARCH_32_PCREL:
+  case ELF::R_LARCH_64:
+  case ELF::R_LARCH_ADD8:
+  case ELF::R_LARCH_SUB8:
+  case ELF::R_LARCH_ADD16:
+  case ELF::R_LARCH_SUB16:
+  case ELF::R_LARCH_ADD32:
+  case ELF::R_LARCH_SUB32:
+  case ELF::R_LARCH_ADD64:
+  case ELF::R_LARCH_SUB64:
+    return true;
+  default:
+    return false;
+  }
+}
+
+static uint64_t resolveLoongArch(uint64_t Type, uint64_t Offset, uint64_t S,
+                                 uint64_t LocData, int64_t Addend) {
+  switch (Type) {
+  case ELF::R_LARCH_NONE:
+    return LocData;
+  case ELF::R_LARCH_32:
+    return (S + Addend) & 0xFFFFFFFF;
+  case ELF::R_LARCH_32_PCREL:
+    return (S + Addend - Offset) & 0xFFFFFFFF;
+  case ELF::R_LARCH_64:
+    return S + Addend;
+  case ELF::R_LARCH_ADD8:
+    return (LocData + (S + Addend)) & 0xFF;
+  case ELF::R_LARCH_SUB8:
+    return (LocData - (S + Addend)) & 0xFF;
+  case ELF::R_LARCH_ADD16:
+    return (LocData + (S + Addend)) & 0xFFFF;
+  case ELF::R_LARCH_SUB16:
+    return (LocData - (S + Addend)) & 0xFFFF;
+  case ELF::R_LARCH_ADD32:
+    return (LocData + (S + Addend)) & 0xFFFFFFFF;
+  case ELF::R_LARCH_SUB32:
+    return (LocData - (S + Addend)) & 0xFFFFFFFF;
+  case ELF::R_LARCH_ADD64:
+    return (LocData + (S + Addend));
+  case ELF::R_LARCH_SUB64:
+    return (LocData - (S + Addend));
+  default:
+    llvm_unreachable("Invalid relocation type");
+  }
+}
+
 static bool supportsCOFFX86(uint64_t Type) {
   switch (Type) {
   case COFF::IMAGE_REL_I386_SECREL:
   case COFF::IMAGE_REL_I386_DIR32:
     return true;
   default:
     return false;
   }
if (Obj.getBytesInAddress() == 8) {
       case Triple::x86_64:
         return {supportsX86_64, resolveX86_64};
       case Triple::aarch64:
       case Triple::aarch64_be:
         return {supportsAArch64, resolveAArch64};
       case Triple::bpfel:
       case Triple::bpfeb:
         return {supportsBPF, resolveBPF};
+      case Triple::loongarch64:
+        return {supportsLoongArch, resolveLoongArch};
       case Triple::mips64el:
       case Triple::mips64:
         return {supportsMips64, resolveMips64};
       case Triple::ppc64le:
       case Triple::ppc64:
         return {supportsPPC64, resolvePPC64};
       case Triple::systemz:
         return {supportsSystemZ, resolveSystemZ};
case Triple::ppc:
       return {supportsPPC32, resolvePPC32};
     case Triple::arm:
     case Triple::armeb:
       return {supportsARM, resolveARM};
     case Triple::avr:
       return {supportsAVR, resolveAVR};
     case Triple::lanai:
       return {supportsLanai, resolveLanai};
+    case Triple::loongarch32:
+      return {supportsLoongArch, resolveLoongArch};
     case Triple::mipsel:
     case Triple::mips:
       return {supportsMips32, resolveMips32};
     case Triple::msp430:
       return {supportsMSP430, resolveMSP430};
     case Triple::sparc:
       return {supportsSparc32, resolveSparc32};
     case Triple::hexagon: