[BOLT][AArch64] Fix printing of relocation types (llvm#166621)

Enumeration of relocation types is not always sequential, e.g. on
AArch64 the first real relocation type is 0x101. As such, the existing
code in `Relocation::print()` was crashing while printing AArch64
relocations. Fix it by using `llvm::object::getELFRelocationTypeName()`.

Author: maksfb

bolt/lib/Core/Relocation.cpp

@@ -1018,41 +1018,15 @@ void Relocation::print(raw_ostream &OS) const {
   default:
     OS << "RType:" << Twine::utohexstr(Type);
     break;
-
-  case Triple::aarch64: {
-    static const char *const AArch64RelocNames[] = {
-#define ELF_RELOC(name, value) #name,
-#include "llvm/BinaryFormat/ELFRelocs/AArch64.def"
-#undef ELF_RELOC
-    };
-    assert(Type < ArrayRef(AArch64RelocNames).size());
-    OS << AArch64RelocNames[Type];
-  } break;
-
+  case Triple::aarch64:
+    OS << object::getELFRelocationTypeName(ELF::EM_AARCH64, Type);
+    break;
   case Triple::riscv64:
-    // RISC-V relocations are not sequentially numbered so we cannot use an
-    // array
-    switch (Type) {
-    default:
-      llvm_unreachable("illegal RISC-V relocation");
-#define ELF_RELOC(name, value)                                                 \
-  case value:                                                                  \
-    OS << #name;                                                               \
+    OS << object::getELFRelocationTypeName(ELF::EM_RISCV, Type);
     break;
-#include "llvm/BinaryFormat/ELFRelocs/RISCV.def"
-#undef ELF_RELOC
-    }
+  case Triple::x86_64:
+    OS << object::getELFRelocationTypeName(ELF::EM_X86_64, Type);
     break;
-
-  case Triple::x86_64: {
-    static const char *const X86RelocNames[] = {
-#define ELF_RELOC(name, value) #name,
-#include "llvm/BinaryFormat/ELFRelocs/x86_64.def"
-#undef ELF_RELOC
-    };
-    assert(Type < ArrayRef(X86RelocNames).size());
-    OS << X86RelocNames[Type];
-  } break;
   }
   OS << ", 0x" << Twine::utohexstr(Offset);
   if (Symbol) {

bolt/test/AArch64/relocation-type-print.s

@@ -0,0 +1,24 @@
+## Verify that llvm-bolt correctly prints relocation types.
+
+# REQUIRES: system-linux
+
+# RUN: %clang %cflags -nostartfiles %s -o %t.exe -Wl,-q,--no-relax
+# RUN: llvm-bolt %t.exe --print-cfg --print-relocations -o %t.bolt \
+# RUN:   | FileCheck %s
+
+  .section .text
+  .align 4
+  .globl _start
+  .type _start, %function
+_start:
+
+  adrp x0, _start
+# CHECK: adrp
+# CHECK-SAME: R_AARCH64_ADR_PREL_PG_HI21
+
+  add x0, x0, :lo12:_start
+# CHECK-NEXT: add
+# CHECK-SAME: R_AARCH64_ADD_ABS_LO12_NC
+
+  ret
+  .size _start, .-_start