Update (2024.10.16)

11541: Prevent load reorder of VarHandle::getOpaque

src/hotspot/cpu/loongarch/loongarch_64.ad

@@ -6438,6 +6438,17 @@ instruct membar_storestore() %{
   ins_pipe(empty);
 %}
 
+instruct same_addr_load_fence() %{
+  match(SameAddrLoadFence);
+  ins_cost(400);
+
+  format %{ "MEMBAR @ same_addr_load_fence" %}
+  ins_encode %{
+    __ dbar(0x700);
+  %}
+  ins_pipe(pipe_slow);
+%}
+
 //----------Move Instructions--------------------------------------------------
 instruct castX2P(mRegP dst, mRegL src) %{
   match(Set dst (CastX2P src));

src/hotspot/share/adlc/formssel.cpp

@@ -22,6 +22,12 @@
  *
  */
 
+/*
+ * This file has been modified by Loongson Technology in 2023, These
+ * modifications are Copyright (c) 2023, Loongson Technology, and are made
+ * available on the same license terms set forth above.
+ */
+
 // FORMS.CPP - Definitions for ADL Parser Forms Classes
 #include "adlc.hpp"
 
@@ -4109,6 +4115,7 @@ bool MatchRule::is_ideal_membar() const {
     !strcmp(_opType,"MemBarVolatile") ||
     !strcmp(_opType,"MemBarCPUOrder") ||
     !strcmp(_opType,"MemBarStoreStore") ||
+    !strcmp(_opType,"SameAddrLoadFence" ) ||
     !strcmp(_opType,"OnSpinWait");
 }
 

src/hotspot/share/gc/shared/c2/barrierSetC2.cpp

@@ -22,6 +22,12 @@
  *
  */
 
+/*
+ * This file has been modified by Loongson Technology in 2023, These
+ * modifications are Copyright (c) 2023, Loongson Technology, and are made
+ * available on the same license terms set forth above.
+ */
+
 #include "precompiled.hpp"
 #include "gc/shared/c2/barrierSetC2.hpp"
 #include "opto/arraycopynode.hpp"
@@ -197,6 +203,8 @@ class C2AccessFence: public StackObj {
 
     bool is_volatile = (decorators & MO_SEQ_CST) != 0;
     bool is_acquire = (decorators & MO_ACQUIRE) != 0;
+    bool is_relaxed = (decorators & MO_RELAXED) != 0;
+    bool is_unsafe = (decorators & C2_UNSAFE_ACCESS) != 0;
 
     // If reference is volatile, prevent following volatiles ops from
     // floating up before the volatile access.
@@ -227,6 +235,13 @@ class C2AccessFence: public StackObj {
         assert(_leading_membar == NULL || support_IRIW_for_not_multiple_copy_atomic_cpu, "no leading membar expected");
         Node* mb = kit->insert_mem_bar(Op_MemBarAcquire, n);
         mb->as_MemBar()->set_trailing_load();
+      } else if (is_relaxed && is_unsafe) {
+#ifdef LOONGARCH64
+        assert(kit != NULL, "unsupported at optimization time");
+        Node* n = _access.raw_access();
+        Node* mb = kit->insert_mem_bar(Op_SameAddrLoadFence, n);
+        mb->as_MemBar()->set_trailing_load();
+#endif
       }
     }
   }

src/hotspot/share/opto/classes.hpp

@@ -22,6 +22,12 @@
  *
  */
 
+/*
+ * This file has been modified by Loongson Technology in 2023, These
+ * modifications are Copyright (c) 2023, Loongson Technology, and are made
+ * available on the same license terms set forth above.
+ */
+
 #include "utilities/macros.hpp"
 
 // The giant table of Node classes.
@@ -217,6 +223,7 @@ macro(StoreFence)
 macro(MemBarReleaseLock)
 macro(MemBarVolatile)
 macro(MemBarStoreStore)
+macro(SameAddrLoadFence)
 macro(MergeMem)
 macro(MinD)
 macro(MinF)

src/hotspot/share/opto/compile.cpp

@@ -22,6 +22,12 @@
  *
  */
 
+/*
+ * This file has been modified by Loongson Technology in 2023, These
+ * modifications are Copyright (c) 2023, Loongson Technology, and are made
+ * available on the same license terms set forth above.
+ */
+
 #include "precompiled.hpp"
 #include "asm/macroAssembler.hpp"
 #include "asm/macroAssembler.inline.hpp"
@@ -3448,6 +3454,7 @@ void Compile::final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc) {
       n->set_req(MemBarNode::Precedent, top());
     }
     break;
+  case Op_SameAddrLoadFence:
   case Op_MemBarAcquire: {
     if (n->as_MemBar()->trailing_load() && n->req() > MemBarNode::Precedent) {
       // At parse time, the trailing MemBarAcquire for a volatile load

src/hotspot/share/opto/memnode.cpp

@@ -22,6 +22,12 @@
  *
  */
 
+/*
+ * This file has been modified by Loongson Technology in 2023, These
+ * modifications are Copyright (c) 2023, Loongson Technology, and are made
+ * available on the same license terms set forth above.
+ */
+
 #include "precompiled.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "compiler/compileLog.hpp"
@@ -3190,6 +3196,7 @@ MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
   case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
   case Op_MemBarVolatile:    return new MemBarVolatileNode(C, atp, pn);
   case Op_MemBarCPUOrder:    return new MemBarCPUOrderNode(C, atp, pn);
+  case Op_SameAddrLoadFence: return new SameAddrLoadFenceNode(C, atp, pn);
   case Op_OnSpinWait:        return new OnSpinWaitNode(C, atp, pn);
   case Op_Initialize:        return new InitializeNode(C, atp, pn);
   case Op_MemBarStoreStore:  return new MemBarStoreStoreNode(C, atp, pn);

src/hotspot/share/opto/memnode.hpp

@@ -22,6 +22,12 @@
  *
  */
 
+/*
+ * This file has been modified by Loongson Technology in 2023, These
+ * modifications are Copyright (c) 2023, Loongson Technology, and are made
+ * available on the same license terms set forth above.
+ */
+
 #ifndef SHARE_VM_OPTO_MEMNODE_HPP
 #define SHARE_VM_OPTO_MEMNODE_HPP
 
@@ -1293,6 +1299,14 @@ class MemBarCPUOrderNode: public MemBarNode {
   virtual uint ideal_reg() const { return 0; } // not matched in the AD file
 };
 
+// Used to prevent LoadLoad reorder for same address.
+class SameAddrLoadFenceNode: public MemBarNode {
+public:
+  SameAddrLoadFenceNode(Compile* C, int alias_idx, Node* precedent)
+    : MemBarNode(C, alias_idx, precedent) {}
+  virtual int Opcode() const;
+};
+
 class OnSpinWaitNode: public MemBarNode {
 public:
   OnSpinWaitNode(Compile* C, int alias_idx, Node* precedent)

src/hotspot/share/runtime/vmStructs.cpp

@@ -22,6 +22,12 @@
  *
  */
 
+/*
+ * This file has been modified by Loongson Technology in 2023, These
+ * modifications are Copyright (c) 2023, Loongson Technology, and are made
+ * available on the same license terms set forth above.
+ */
+
 #include "precompiled.hpp"
 #include "ci/ciField.hpp"
 #include "ci/ciInstance.hpp"
@@ -1642,6 +1648,7 @@ typedef PaddedEnd<ObjectMonitor>              PaddedObjectMonitor;
   declare_c2_type(StoreFenceNode, MemBarNode)                             \
   declare_c2_type(MemBarVolatileNode, MemBarNode)                         \
   declare_c2_type(MemBarCPUOrderNode, MemBarNode)                         \
+  declare_c2_type(SameAddrLoadFenceNode, MemBarNode)                      \
   declare_c2_type(OnSpinWaitNode, MemBarNode)                             \
   declare_c2_type(InitializeNode, MemBarNode)                             \
   declare_c2_type(ThreadLocalNode, Node)                                  \