ELF/AArch64: Add support for R_AARCH64_PREL64

Add support for the R_AARCH64_PREL64 relocation type and add tests.

Patch by Will Newton.

llvm-svn: 234741

lld/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp

@@ -69,6 +69,18 @@ static std::error_code relocR_AARCH64_ABS16(uint8_t *location, uint64_t P,
   return std::error_code();
 }
 
+/// \brief R_AARCH64_PREL64 - word64: S + A - P
+static void relocR_AARCH64_PREL64(uint8_t *location, uint64_t P,
+                                  uint64_t S, int64_t A) {
+  int64_t result = S + A - P;
+  DEBUG(llvm::dbgs() << "\t\tHandle " << LLVM_FUNCTION_NAME << " -";
+        llvm::dbgs() << " S: 0x" << Twine::utohexstr(S);
+        llvm::dbgs() << " A: 0x" << Twine::utohexstr(A);
+        llvm::dbgs() << " P: 0x" << Twine::utohexstr(P);
+        llvm::dbgs() << " result: 0x" << Twine::utohexstr(result) << "\n");
+  write64le(location, result + read64le(location));
+}
+
 /// \brief R_AARCH64_PREL32 - word32: S + A - P
 static std::error_code relocR_AARCH64_PREL32(uint8_t *location, uint64_t P,
                                              uint64_t S, int64_t A) {
@@ -365,6 +377,9 @@ std::error_code AArch64TargetRelocationHandler::applyRelocation(
     return relocR_AARCH64_ABS32(loc, reloc, target, addend);
   case R_AARCH64_ABS16:
     return relocR_AARCH64_ABS16(loc, reloc, target, addend);
+  case R_AARCH64_PREL64:
+    relocR_AARCH64_PREL64(loc, reloc, target, addend);
+    break;
   case R_AARCH64_PREL32:
     return relocR_AARCH64_PREL32(loc, reloc, target, addend);
   // Runtime only relocations. Ignore here.

lld/test/elf/AArch64/rel-prel64.test

@@ -0,0 +1,59 @@
+# Check handling of R_AARCH64_PREL64 relocation.
+# RUN: yaml2obj -format=elf %s > %t-obj
+# RUN: lld -flavor gnu -target arm64 -o %t-exe %t-obj
+# RUN: llvm-objdump -s -t %t-exe | FileCheck %s
+
+# CHECK: Contents of section .data:
+# CHECK-NEXT: 401060 09000000 00000080 f9ffffff ffffff7f ................
+#                    ^^ data2 - data1 + 0x8000000000000001 = 0x8000000000000009
+#                                      ^^ data1 - data2 + 0x8000000000000001 = 0x7ffffffffffffff9
+# CHECK: SYMBOL TABLE:
+# CHECK: 00401060 g  .data  00000008 data1
+# CHECK: 00401068 g  .data  00000008 data2
+
+!ELF
+FileHeader: !FileHeader
+  Class: ELFCLASS64
+  Data: ELFDATA2LSB
+  Type: ET_REL
+  Machine: EM_AARCH64
+
+Sections:
+- Name: .text
+  Type: SHT_PROGBITS
+  Content: "00000000"
+  AddressAlign: 16
+  Flags: [SHF_ALLOC, SHF_EXECINSTR]
+- Name: .data
+  Type: SHT_PROGBITS
+  Content: "00000000000000000000000000000000"
+  AddressAlign: 16
+  Flags: [SHF_ALLOC, SHF_WRITE]
+
+- Name: .rela.data
+  Type: SHT_RELA
+  Info: .data
+  AddressAlign: 8
+  Relocations:
+    - Offset: 0x0
+      Symbol: data2
+      Type: R_AARCH64_PREL64
+      Addend: -9223372036854775807
+    - Offset: 0x8
+      Symbol: data1
+      Type: R_AARCH64_PREL64
+      Addend: -9223372036854775807
+
+Symbols:
+  Global:
+    - Name: _start
+      Section: .text
+      Value: 0x0
+      Size: 4
+    - Name: data1
+      Section: .data
+      Size: 8
+    - Name: data2
+      Section: .data
+      Value: 0x8
+      Size: 8