[ELF/AArch64] Support R_AARCH64_LDST128_ABS_LO12_NC relocation

[davide]

Summary

This is needed to self-host lld on FreeBSD. I've been sitting with this (and other relocation patches) in my local tree for a while.

[ruiu]

LGTM

[davide]

Committed. Thanks!

ELF/Target.cpp

   case R_AARCH64_ABS32:
   case R_AARCH64_ABS64:
   case R_AARCH64_ADD_ABS_LO12_NC:
   case R_AARCH64_ADR_PREL_LO21:
   case R_AARCH64_ADR_PREL_PG_HI21:
   case R_AARCH64_LDST8_ABS_LO12_NC:
   case R_AARCH64_LDST32_ABS_LO12_NC:
   case R_AARCH64_LDST64_ABS_LO12_NC:
+  case R_AARCH64_LDST128_ABS_LO12_NC:
     if (auto *SS = dyn_cast<SharedSymbol<ELF64LE>>(&S))
       return SS->Sym.getType() == STT_OBJECT;
     return false;
   }
 }
 
 bool AArch64TargetInfo::relocNeedsGot(uint32_t Type,
                                       const SymbolBody &S) const {

     or32le(Loc, (X & 0x1FFFFC) << 3);
     break;
   }
   case R_AARCH64_LD64_GOT_LO12_NC:
   case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
     checkAlignment<8>(SA, Type);
     or32le(Loc, (SA & 0xFF8) << 7);
     break;
+  case R_AARCH64_LDST128_ABS_LO12_NC:
+    or32le(Loc, (SA & 0x0FF8) << 6);
+    break;
   case R_AARCH64_LDST8_ABS_LO12_NC:
     or32le(Loc, (SA & 0xFFF) << 10);
     break;
   case R_AARCH64_LDST32_ABS_LO12_NC:
     or32le(Loc, (SA & 0xFFC) << 8);
     break;
   case R_AARCH64_LDST64_ABS_LO12_NC:
     or32le(Loc, (SA & 0xFF8) << 7);

test/ELF/aarch64-relocs.s

foo8:
   .size mystr, 3
 
 # S = 0x11044, A = 0x4
 # R = ((S + A) & 0xFFF) << 10 = 0x00012000
 # 0x00012000 | 0x398001ab = 0x398121ab
 # CHECK: Disassembly of section .R_AARCH64_LDST8_ABS_LO12_NC:
 # CHECK-NEXT: ldst8:
 # CHECK-NEXT:   11044:       ab 21 81 39     ldrsb x11, [x13, #72]
+
+.section .R_AARCH64_LDST128_ABS_LO12_NC,"ax",@progbits
+ldst128:
+  ldr q20, [x19, #:lo12:foo128]
+foo128:
+  .asciz "foo"
+  .size mystr, 3
+
+# S = 0x1104c, A = 0x4
+# R = ((S + A) & 0xFF8) << 6 = 0x00001400
+# 0x00001400 | 0x3dc00274 = 0x3dc01674
+# CHECK: Disassembly of section .R_AARCH64_LDST128_ABS_LO12_NC:
+# CHECK: ldst128:
+# CHECK:   1104c:       74 16 c0 3d     ldr     q20, [x19, #80]
+#foo128:
+#   11050:       66 6f 6f 00     .word