[JITLink][ELF/AARCH64] Implement R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_ADD_ABS_LO12_NC

[sunho]

Summary

This implements R_AARCH64_ADR_PREL_PG_HI21 and R_AARCH64_ADD_ABS_LO12_NC fixup edges using the generic aarch64 patch edges.

[sunho]

Have to mention the test case is taken from https://reviews.llvm.org/D118346 by @dongAxis1944

[sunho]

Rename edges so that it's easy to find original relocation type.

[sunho]

Merge testcases

[sgraenitz]

Thanks for your patch. The tests look good and appear to work fine on my machine. Will have a closer look at it towards the end of the week.

llvm/lib/ExecutionEngine/JITLink/ELF_aarch64.cpp

62

The using namespace on file level makes the explicit qualifications here redundant right? It's a detail, but let's agree on one option and stick to it consistently. (More cases below.)

llvm/test/ExecutionEngine/JITLink/AArch64/ELF_aarch64_relocations.s

50

The value of p2align varies between test cases. How does it affect the resolution? (Trying other values like 1 or 2 doesn't fail the test.)

[sunho]

Update the code

llvm/lib/ExecutionEngine/JITLink/ELF_aarch64.cpp

62

In other backends, using namespace seems to be more common. I changed the code to consistently do without namespace.

llvm/test/ExecutionEngine/JITLink/AArch64/ELF_aarch64_relocations.s

50

It didn't affect the test result since we don't execute the code (-noexec), but in arm64, function entries need to be aligned to 4 bytes. Although techincally not required, I just added p2align 2 to function entry for the sake of cleaness.

The reason for p2align 4 in named_data is since it might be used to test 128bit/64bit data load/store.

[sunho]

Use enum without namespace in getELFAArch64RelocationKindName

[sgraenitz]

LGTM, thanks for working on this!

llvm/test/ExecutionEngine/JITLink/AArch64/ELF_aarch64_relocations.s

50

Alright, thanks for the explanation.

The reason for p2align 4 in named_data is since it might be used to test 128bit/64bit data load/store

Yes, I realized that it makes a difference once I found it's used for the LDST relocations from D126630 as well.

[sunho]

Rebase

[lhames]

LGTM -- Thanks very much @sunho!

llvm/lib/ExecutionEngine/JITLink/ELF_aarch64.cpp

Error applyFixup(LinkGraph &G, Block &B, const Edge &E) const {
     return aarch64::applyFixup(G, B, E);
   }
 };
 
 template <typename ELFT>
 class ELFLinkGraphBuilder_aarch64 : public ELFLinkGraphBuilder<ELFT> {
 private:
   enum ELFAArch64RelocationKind : Edge::Kind {
-    ELFBranch26 = Edge::FirstRelocation,
+    ELFCall26 = Edge::FirstRelocation,
+    ELFAdrPage21,
+    ELFAddAbs12,
   };
 
   static Expected<ELFAArch64RelocationKind>
   getRelocationKind(const uint32_t Type) {
     using namespace aarch64;
     switch (Type) {
     case ELF::R_AARCH64_CALL26:
-      return ELFBranch26;
+      return ELFCall26;
+    case ELF::R_AARCH64_ADR_PREL_PG_HI21:
+      return ELFAdrPage21;
+    case ELF::R_AARCH64_ADD_ABS_LO12_NC:
+      return ELFAddAbs12;
     }
 
     return make_error<JITLinkError>("Unsupported aarch64 relocation:" +
                                     formatv("{0:d}", Type));
   }
 
   Error addRelocations() override {
     LLVM_DEBUG(dbgs() << "Processing relocations:\n");
Error addSingleRelocation(const typename ELFT::Rela &Rel,
     int64_t Addend = Rel.r_addend;
     orc::ExecutorAddr FixupAddress =
         orc::ExecutorAddr(FixupSect.sh_addr) + Rel.r_offset;
     Edge::OffsetT Offset = FixupAddress - BlockToFix.getAddress();
 
     Edge::Kind Kind = Edge::Invalid;
 
     switch (*RelocKind) {
-    case ELFBranch26: {
+    case ELFCall26: {
       Kind = aarch64::Branch26;
       break;
     }
+    case ELFAdrPage21: {
+      Kind = aarch64::Page21;
+      break;
+    }
+    case ELFAddAbs12: {
+      Kind = aarch64::PageOffset12;
+      break;
+    }
     };
 
     Edge GE(Kind, Offset, *GraphSymbol, Addend);
     LLVM_DEBUG({
       dbgs() << "    ";
       printEdge(dbgs(), BlockToFix, GE, aarch64::getEdgeKindName(Kind));
       dbgs() << "\n";
     });
 
     BlockToFix.addEdge(std::move(GE));
     return Error::success();
   }
 
   /// Return the string name of the given ELF aarch64 edge kind.
   const char *getELFAArch64RelocationKindName(Edge::Kind R) {
     switch (R) {
-    case ELFBranch26:
-      return "ELFBranch26";
+    case ELFCall26:
+      return "ELFCall26";
+    case ELFAdrPage21:
+      return "ELFAdrPage21";
+    case ELFAddAbs12:
+      return "ELFAddAbs12";
     default:
       return getGenericEdgeKindName(static_cast<Edge::Kind>(R));
     }
   }
 
 public:
   ELFLinkGraphBuilder_aarch64(StringRef FileName,
                               const object::ELFFile<ELFT> &Obj, const Triple T)

llvm/test/ExecutionEngine/JITLink/AArch64/ELF_aarch64_relocations.s

+# RUN: rm -rf %t && mkdir -p %t
+# RUN: llvm-mc -triple=aarch64-unknown-linux-gnu -relax-relocations=false -position-independent -filetype=obj -o %t/elf_reloc.o %s
+# RUN: llvm-jitlink -noexec -check %s %t/elf_reloc.o
+
+        .text
+
+        .globl  main
+        .p2align  2
+        .type main,@function
+main:
+        ret
+
+        .size   main, .-main
+
+# Check R_AARCH64_CALL26 relocation of a local function call
+#
+# jitlink-check: decode_operand(local_func_call26, 0)[25:0] = (local_func - local_func_call26)[27:2]
+        .globl  local_func
+        .p2align  2
+        .type local_func,@function
+local_func:
+        ret
+        .size   local_func, .-local_func
+
+        .globl  local_func_call26
+        .p2align  2
+local_func_call26:
+        bl  local_func
+        .size   local_func_call26, .-local_func_call26
+
+
+# Check R_AARCH64_ADR_PREL_PG_HI21 / R_AARCH64_ADD_ABS_LO12_NC relocation of a local symbol
+#
+# For the ADR_PREL_PG_HI21/ADRP instruction we have the 21-bit delta to the 4k page
+# containing the global.
+#
+# jitlink-check: decode_operand(test_adr_prel, 1) = (named_data - test_adr_prel)[32:12]
+# jitlink-check: decode_operand(test_add_abs_lo12, 2) = (named_data + 0)[11:0]
+        .globl  test_adr_prel
+        .p2align  2
+test_adr_prel:
+        adrp  x0, named_data
+        .size test_adr_prel, .-test_adr_prel
+
+        .globl  test_add_abs_lo12
+        .p2align  2
+test_add_abs_lo12:
+        add x0, x0, :lo12:named_data
+        .size test_add_abs_lo12, .-test_add_abs_lo12
+
+        .globl  named_data
+        .p2align  4
+        .type   named_data,@object
+named_data:
+        .quad   0x2222222222222222
+        .quad   0x3333333333333333
+        .size   named_data, .-named_data