6889740: G1: OpenDS fails with "unhandled exception in compiled code" Summary: Incorrect code was being generated for the store operation in the null case of the aastore bytecode template. The bad code was generated by the store_heap_oop routine which takes a Register as its second argument. Passing NULL_WORD (0) as the second argument causes the value to be converted to Register(0), which is rax. Thus the generated store was "mov (dst), $rax" instead of "mov (dst), $0x0". Changed calls to store_heap_oop that pass NULL_WORD as the second argument to a new routine store_heap_oop_null. Reviewed-by: kvn, twisti

--- a/src/cpu/x86/vm/assembler_x86.cpp	Wed Oct 28 11:16:42 2009 -0700
+++ b/src/cpu/x86/vm/assembler_x86.cpp	Thu Oct 29 09:42:26 2009 -0700
@@ -8214,6 +8214,15 @@
   }
 }
 
+// Used for storing NULLs.
+void MacroAssembler::store_heap_oop_null(Address dst) {
+  if (UseCompressedOops) {
+    movl(dst, (int32_t)NULL_WORD);
+  } else {
+    movslq(dst, (int32_t)NULL_WORD);
+  }
+}
+
 // Algorithm must match oop.inline.hpp encode_heap_oop.
 void MacroAssembler::encode_heap_oop(Register r) {
   assert (UseCompressedOops, "should be compressed");