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diff src/cpu/sparc/vm/c1_CodeStubs_sparc.cpp @ 3249:e1162778c1c8

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7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer. Reviewed-by: kvn, iveresov, never, tonyp, dholmes
author johnc
date Thu, 07 Apr 2011 09:53:20 -0700
parents 32f7097f9d8f
children 59766fd005ff
line wrap: on
line diff
--- a/src/cpu/sparc/vm/c1_CodeStubs_sparc.cpp	Tue Apr 05 19:14:03 2011 -0700
+++ b/src/cpu/sparc/vm/c1_CodeStubs_sparc.cpp	Thu Apr 07 09:53:20 2011 -0700
@@ -408,13 +408,20 @@
 #ifndef SERIALGC
 
 void G1PreBarrierStub::emit_code(LIR_Assembler* ce) {
+  // At this point we know that marking is in progress.
+  // If do_load() is true then we have to emit the
+  // load of the previous value; otherwise it has already
+  // been loaded into _pre_val.
+
   __ bind(_entry);
 
   assert(pre_val()->is_register(), "Precondition.");
-
   Register pre_val_reg = pre_val()->as_register();
 
-  ce->mem2reg(addr(), pre_val(), T_OBJECT, patch_code(), info(), false /*wide*/, false /*unaligned*/);
+  if (do_load()) {
+    ce->mem2reg(addr(), pre_val(), T_OBJECT, patch_code(), info(), false /*wide*/, false /*unaligned*/);
+  }
+
   if (__ is_in_wdisp16_range(_continuation)) {
     __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
                       pre_val_reg, _continuation);
@@ -431,6 +438,96 @@
 
 }
 
+void G1UnsafeGetObjSATBBarrierStub::emit_code(LIR_Assembler* ce) {
+  // At this point we know that offset == referent_offset.
+  //
+  // So we might have to emit:
+  //   if (src == null) goto continuation.
+  //
+  // and we definitely have to emit:
+  //   if (klass(src).reference_type == REF_NONE) goto continuation
+  //   if (!marking_active) goto continuation
+  //   if (pre_val == null) goto continuation
+  //   call pre_barrier(pre_val)
+  //   goto continuation
+  //
+  __ bind(_entry);
+
+  assert(src()->is_register(), "sanity");
+  Register src_reg = src()->as_register();
+
+  if (gen_src_check()) {
+    // The original src operand was not a constant.
+    // Generate src == null?
+    if (__ is_in_wdisp16_range(_continuation)) {
+      __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
+                        src_reg, _continuation);
+    } else {
+      __ cmp(src_reg, G0);
+      __ brx(Assembler::equal, false, Assembler::pt, _continuation);
+    }
+    __ delayed()->nop();
+  }
+
+  // Generate src->_klass->_reference_type() == REF_NONE)?
+  assert(tmp()->is_register(), "sanity");
+  Register tmp_reg = tmp()->as_register();
+
+  __ load_klass(src_reg, tmp_reg);
+
+  Address ref_type_adr(tmp_reg, instanceKlass::reference_type_offset_in_bytes() + sizeof(oopDesc));
+  __ ld(ref_type_adr, tmp_reg);
+
+  if (__ is_in_wdisp16_range(_continuation)) {
+    __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
+                      tmp_reg, _continuation);
+  } else {
+    __ cmp(tmp_reg, G0);
+    __ brx(Assembler::equal, false, Assembler::pt, _continuation);
+  }
+  __ delayed()->nop();
+
+  // Is marking active?
+  assert(thread()->is_register(), "precondition");
+  Register thread_reg = thread()->as_register();
+
+  Address in_progress(thread_reg, in_bytes(JavaThread::satb_mark_queue_offset() +
+                                       PtrQueue::byte_offset_of_active()));
+
+  if (in_bytes(PtrQueue::byte_width_of_active()) == 4) {
+    __ ld(in_progress, tmp_reg);
+  } else {
+    assert(in_bytes(PtrQueue::byte_width_of_active()) == 1, "Assumption");
+    __ ldsb(in_progress, tmp_reg);
+  }
+  if (__ is_in_wdisp16_range(_continuation)) {
+    __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
+                      tmp_reg, _continuation);
+  } else {
+    __ cmp(tmp_reg, G0);
+    __ brx(Assembler::equal, false, Assembler::pt, _continuation);
+  }
+  __ delayed()->nop();
+
+  // val == null?
+  assert(val()->is_register(), "Precondition.");
+  Register val_reg = val()->as_register();
+
+  if (__ is_in_wdisp16_range(_continuation)) {
+    __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
+                      val_reg, _continuation);
+  } else {
+    __ cmp(val_reg, G0);
+    __ brx(Assembler::equal, false, Assembler::pt, _continuation);
+  }
+  __ delayed()->nop();
+
+  __ call(Runtime1::entry_for(Runtime1::Runtime1::g1_pre_barrier_slow_id));
+  __ delayed()->mov(val_reg, G4);
+  __ br(Assembler::always, false, Assembler::pt, _continuation);
+  __ delayed()->nop();
+}
+
 jbyte* G1PostBarrierStub::_byte_map_base = NULL;
 
 jbyte* G1PostBarrierStub::byte_map_base_slow() {