There's a violation of the C++ one definition rule in src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp where the class Decoder conflicts with src/hotspot/share/utilities/decoder.hpp:Decoder

This can lead to undefined behavior. I found it to cause crashes in the Sulong LLVM toolchain inside Apple's `ld`.

Attached patch fixes it (or rather, gets me onto the next linker crash...)

--- a/src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp
+++ b/src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp
@@ -392,13 +392,13 @@ static bool offset_for(uint32_t insn1, uint32_t insn2, ptrdiff_t &byte_offset) {
   return false;
 }

-class Decoder : public RelocActions {
- virtual reloc_insn adrpMem() { return &Decoder::adrpMem_impl; }
- virtual reloc_insn adrpAdd() { return &Decoder::adrpAdd_impl; }
- virtual reloc_insn adrpMovk() { return &Decoder::adrpMovk_impl; }
+class Aarch64Decoder : public RelocActions {
+ virtual reloc_insn adrpMem() { return &Aarch64Decoder::adrpMem_impl; }
+ virtual reloc_insn adrpAdd() { return &Aarch64Decoder::adrpAdd_impl; }
+ virtual reloc_insn adrpMovk() { return &Aarch64Decoder::adrpMovk_impl; }

 public:
- Decoder(address insn_addr, uint32_t insn) : RelocActions(insn_addr, insn) {}
+ Aarch64Decoder(address insn_addr, uint32_t insn) : RelocActions(insn_addr, insn) {}

   virtual int loadStore(address insn_addr, address &target) {
     intptr_t offset = Instruction_aarch64::sextract(_insn, 23, 5);
@@ -494,7 +494,7 @@ class Decoder : public RelocActions {
 };

 address MacroAssembler::target_addr_for_insn(address insn_addr, uint32_t insn) {
- Decoder decoder(insn_addr, insn);
+ Aarch64Decoder decoder(insn_addr, insn);
   address target;
   decoder.run(insn_addr, target);
   return target;