src/cpu/aarch64/vm/macroAssembler_aarch64.cpp

@@ -39,10 +39,11 @@
 #include "opto/node.hpp"
 #include "runtime/biasedLocking.hpp"
 #include "runtime/icache.hpp"
 #include "runtime/interfaceSupport.hpp"
 #include "runtime/sharedRuntime.hpp"
+#include "runtime/thread.hpp"
 
 #if INCLUDE_ALL_GCS
 #include "gc/g1/g1CollectedHeap.inline.hpp"
 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
 #include "gc/g1/heapRegion.hpp"

@@ -4647,5 +4648,26 @@
       br(GT, NEXT_1);
 
     BIND(DONE);
       sub(result, result, len); // Return index where we stopped
 }
+
+// get_thread can be called anywhere inside generated code so we need
+// to save whatever non-callee save context might get clobbered by the
+// call to Thread::current or, indeed, the call setup code. 
+// x86 appears to save C arg registers.
+
+void MacroAssembler::get_thread(Register dst) {
+
+  // Save all call-clobbered regs except dst, plus r19 and r20.
+  RegSet saved_regs = RegSet::range(r0, r20) + lr - dst;
+  push(saved_regs, sp);
+
+  // FIX-ME: implement
+  // return Thread::current()
+
+  if (dst != c_rarg0) {
+    mov(dst, c_rarg0);
+  }
+  // restore pushed registers
+  pop(saved_regs, sp);
+}