8227384: C2 compilation fails with "graph should be schedulable" when running with -XX:-EliminateLocks

Reviewed-by: thartmann, kvn

src/hotspot/share/opto/callnode.cpp

@@ -1397,6 +1397,18 @@ void AllocateNode::compute_MemBar_redundancy(ciMethod* initializer)
     _is_allocation_MemBar_redundant = true;
   }
 }
+Node *AllocateNode::make_ideal_mark(PhaseGVN *phase, Node* obj, Node* control, Node* mem) {
+  Node* mark_node = NULL;
+  // For now only enable fast locking for non-array types
+  if (UseBiasedLocking && Opcode() == Op_Allocate) {
+    Node* klass_node = in(AllocateNode::KlassNode);
+    Node* proto_adr = phase->transform(new AddPNode(klass_node, klass_node, phase->MakeConX(in_bytes(Klass::prototype_header_offset()))));
+    mark_node = LoadNode::make(*phase, control, mem, proto_adr, TypeRawPtr::BOTTOM, TypeX_X, TypeX_X->basic_type(), MemNode::unordered);
+  } else {
+    mark_node = phase->MakeConX(markWord::prototype().value());
+  }
+  return mark_node;
+}
 
 //=============================================================================
 Node* AllocateArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {

src/hotspot/share/opto/callnode.hpp

@@ -936,6 +936,8 @@ public:
   // allocation node.
   void compute_MemBar_redundancy(ciMethod* initializer);
   bool is_allocation_MemBar_redundant() { return _is_allocation_MemBar_redundant; }
+
+  Node* make_ideal_mark(PhaseGVN *phase, Node* obj, Node* control, Node* mem);
 };
 
 //------------------------------AllocateArray---------------------------------

src/hotspot/share/opto/macro.cpp

@@ -1652,14 +1652,11 @@ PhaseMacroExpand::initialize_object(AllocateNode* alloc,
                                     Node* size_in_bytes) {
   InitializeNode* init = alloc->initialization();
   // Store the klass & mark bits
-  Node* mark_node = NULL;
-  // For now only enable fast locking for non-array types
-  if (UseBiasedLocking && (length == NULL)) {
-    mark_node = make_load(control, rawmem, klass_node, in_bytes(Klass::prototype_header_offset()), TypeRawPtr::BOTTOM, T_ADDRESS);
-  } else {
-    mark_node = makecon(TypeRawPtr::make((address)markWord::prototype().value()));
+  Node* mark_node = alloc->make_ideal_mark(&_igvn, object, control, rawmem);
+  if (!mark_node->is_Con()) {
+    transform_later(mark_node);
   }
-  rawmem = make_store(control, rawmem, object, oopDesc::mark_offset_in_bytes(), mark_node, T_ADDRESS);
+  rawmem = make_store(control, rawmem, object, oopDesc::mark_offset_in_bytes(), mark_node, TypeX_X->basic_type());
 
   rawmem = make_store(control, rawmem, object, oopDesc::klass_offset_in_bytes(), klass_node, T_METADATA);
   int header_size = alloc->minimum_header_size();  // conservatively small
@@ -2596,15 +2593,36 @@ bool PhaseMacroExpand::expand_macro_nodes() {
     if (_igvn.type(n) == Type::TOP || (n->in(0) != NULL && n->in(0)->is_top())) {
       // node is unreachable, so don't try to expand it
       C->remove_macro_node(n);
-    } else if (n->is_ArrayCopy()){
-      int macro_count = C->macro_count();
+      continue;
+    }
+    int macro_count = C->macro_count();
+    switch (n->class_id()) {
+    case Node::Class_Lock:
+      expand_lock_node(n->as_Lock());
+      assert(C->macro_count() < macro_count, "must have deleted a node from macro list");
+      break;
+    case Node::Class_Unlock:
+      expand_unlock_node(n->as_Unlock());
+      assert(C->macro_count() < macro_count, "must have deleted a node from macro list");
+      break;
+    case Node::Class_ArrayCopy:
       expand_arraycopy_node(n->as_ArrayCopy());
       assert(C->macro_count() < macro_count, "must have deleted a node from macro list");
+      break;
     }
     if (C->failing())  return true;
     macro_idx --;
   }
 
+  // All nodes except Allocate nodes are expanded now. There could be
+  // new optimization opportunities (such as folding newly created
+  // load from a just allocated object). Run IGVN.
+  _igvn.set_delay_transform(false);
+  _igvn.optimize();
+  if (C->failing())  return true;
+
+  _igvn.set_delay_transform(true);
+
   // expand "macro" nodes
   // nodes are removed from the macro list as they are processed
   while (C->macro_count() > 0) {
@@ -2623,12 +2641,6 @@ bool PhaseMacroExpand::expand_macro_nodes() {
     case Node::Class_AllocateArray:
       expand_allocate_array(n->as_AllocateArray());
       break;
-    case Node::Class_Lock:
-      expand_lock_node(n->as_Lock());
-      break;
-    case Node::Class_Unlock:
-      expand_unlock_node(n->as_Unlock());
-      break;
     default:
       assert(false, "unknown node type in macro list");
     }

src/hotspot/share/opto/memnode.cpp

@@ -1555,6 +1555,22 @@ Node *LoadNode::split_through_phi(PhaseGVN *phase) {
   return phi;
 }
 
+AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
+  if (Opcode() == Op_LoadX) {
+    Node* address = in(MemNode::Address);
+    AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
+    Node* mem = in(MemNode::Memory);
+    if (alloc != NULL && mem->is_Proj() &&
+        mem->in(0) != NULL &&
+        mem->in(0) == alloc->initialization() &&
+        alloc->initialization()->proj_out_or_null(0) != NULL) {
+      return alloc;
+    }
+  }
+  return NULL;
+}
+
+
 //------------------------------Ideal------------------------------------------
 // If the load is from Field memory and the pointer is non-null, it might be possible to
 // zero out the control input.
@@ -1683,6 +1699,13 @@ Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
     }
   }
 
+  AllocateNode* alloc = is_new_object_mark_load(phase);
+  if (alloc != NULL && alloc->Opcode() == Op_Allocate && UseBiasedLocking) {
+    InitializeNode* init = alloc->initialization();
+    Node* control = init->proj_out(0);
+    return alloc->make_ideal_mark(phase, address, control, mem);
+  }
+
   return progress ? this : NULL;
 }
 
@@ -1941,6 +1964,12 @@ const Type* LoadNode::Value(PhaseGVN* phase) const {
       return Type::get_zero_type(_type->basic_type());
     }
   }
+
+  Node* alloc = is_new_object_mark_load(phase);
+  if (alloc != NULL && !(alloc->Opcode() == Op_Allocate && UseBiasedLocking)) {
+    return TypeX::make(markWord::prototype().value());
+  }
+
   return _type;
 }
 

src/hotspot/share/opto/memnode.hpp

@@ -183,6 +183,8 @@ private:
 
   uint _barrier; // Bit field with barrier information
 
+  AllocateNode* is_new_object_mark_load(PhaseGVN *phase) const;
+
 protected:
   virtual bool cmp(const Node &n) const;
   virtual uint size_of() const; // Size is bigger

src/hotspot/share/opto/type.hpp

@@ -1791,6 +1791,7 @@ inline bool Type::is_ptr_to_boxing_obj() const {
 #define Op_SubX      Op_SubL
 #define Op_XorX      Op_XorL
 #define Op_URShiftX  Op_URShiftL
+#define Op_LoadX     Op_LoadL
 // conversions
 #define ConvI2X(x)   ConvI2L(x)
 #define ConvL2X(x)   (x)
@@ -1838,6 +1839,7 @@ inline bool Type::is_ptr_to_boxing_obj() const {
 #define Op_SubX      Op_SubI
 #define Op_XorX      Op_XorI
 #define Op_URShiftX  Op_URShiftI
+#define Op_LoadX     Op_LoadI
 // conversions
 #define ConvI2X(x)   (x)
 #define ConvL2X(x)   ConvL2I(x)

test/hotspot/jtreg/compiler/escapeAnalysis/TestEliminateLocksOffCrash.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8227384
+ * @summary C2 compilation fails with "graph should be schedulable" when running with -XX:-EliminateLocks
+ *
+ * @run main/othervm -XX:-EliminateLocks TestEliminateLocksOffCrash
+ */
+
+public class TestEliminateLocksOffCrash {
+    public static void main(String[] args) {
+        for (int i = 0; i < 20_000; i++) {
+            try {
+                test();
+            } catch (Exception e) {
+            }
+        }
+    }
+
+    private static void test() throws Exception {
+        Object obj = new Object();
+        synchronized (obj) {
+            throw new Exception();
+        }
+    }
+}