6791178: Specialize for zero as the compressed oop vm heap base

Summary: Use zero based compressed oops if java heap is below 32gb and unscaled compressed oops if java heap is below 4gb.
Reviewed-by: never, twisti, jcoomes, coleenp

agent/src/share/classes/sun/jvm/hotspot/debugger/Debugger.java

@@ -118,9 +118,9 @@ public interface Debugger extends SymbolLookup, ThreadAccess {
   public long getJIntSize();
   public long getJLongSize();
   public long getJShortSize();
-  public long getHeapBase();
   public long getHeapOopSize();
-  public long getLogMinObjAlignmentInBytes();
+  public long getNarrowOopBase();
+  public int  getNarrowOopShift();
 
   public ReadResult readBytesFromProcess(long address, long numBytes)
     throws DebuggerException;

agent/src/share/classes/sun/jvm/hotspot/debugger/DebuggerBase.java

@@ -56,8 +56,8 @@ public abstract class DebuggerBase implements Debugger {
   // heap data.
   protected long oopSize;
   protected long heapOopSize;
-  protected long heapBase;                 // heap base for compressed oops.
-  protected long logMinObjAlignmentInBytes; // Used to decode compressed oops.
+  protected long narrowOopBase;  // heap base for compressed oops.
+  protected int  narrowOopShift; // shift to decode compressed oops.
   // Should be initialized if desired by calling initCache()
   private PageCache cache;
 
@@ -159,10 +159,10 @@ public abstract class DebuggerBase implements Debugger {
     javaPrimitiveTypesConfigured = true;
   }
 
-  public void putHeapConst(long heapBase, long heapOopSize, long logMinObjAlignmentInBytes) {
-    this.heapBase = heapBase;
+  public void putHeapConst(long heapOopSize, long narrowOopBase, int narrowOopShift) {
     this.heapOopSize = heapOopSize;
-    this.logMinObjAlignmentInBytes = logMinObjAlignmentInBytes;
+    this.narrowOopBase = narrowOopBase;
+    this.narrowOopShift = narrowOopShift;
   }
 
   /** May be called by subclasses if desired to initialize the page
@@ -459,7 +459,7 @@ public abstract class DebuggerBase implements Debugger {
     long value = readCInteger(address, getHeapOopSize(), true);
     if (value != 0) {
       // See oop.inline.hpp decode_heap_oop
-      value = (long)(heapBase + (long)(value << logMinObjAlignmentInBytes));
+      value = (long)(narrowOopBase + (long)(value << narrowOopShift));
     }
     return value;
   }
@@ -545,10 +545,10 @@ public abstract class DebuggerBase implements Debugger {
     return heapOopSize;
   }
 
-  public long getHeapBase() {
-    return heapBase;
+  public long getNarrowOopBase() {
+    return narrowOopBase;
   }
-  public long getLogMinObjAlignmentInBytes() {
-    return logMinObjAlignmentInBytes;
+  public int getNarrowOopShift() {
+    return narrowOopShift;
   }
 }

agent/src/share/classes/sun/jvm/hotspot/debugger/JVMDebugger.java

@@ -42,5 +42,5 @@ public interface JVMDebugger extends Debugger {
                                               long jintSize,
                                               long jlongSize,
                                               long jshortSize);
-  public void putHeapConst(long heapBase, long heapOopSize, long logMinObjAlignment);
+  public void putHeapConst(long heapOopSize, long narrowOopBase, int narrowOopShift);
 }

agent/src/share/classes/sun/jvm/hotspot/debugger/remote/RemoteDebugger.java

@@ -65,9 +65,10 @@ public interface RemoteDebugger extends Remote {
   public long      getJIntSize() throws RemoteException;
   public long      getJLongSize() throws RemoteException;
   public long      getJShortSize() throws RemoteException;
-  public long      getHeapBase() throws RemoteException;
   public long      getHeapOopSize() throws RemoteException;
-  public long      getLogMinObjAlignmentInBytes() throws RemoteException;
+  public long      getNarrowOopBase() throws RemoteException;
+  public int       getNarrowOopShift() throws RemoteException;
+
   public boolean   areThreadsEqual(long addrOrId1, boolean isAddress1,
                                    long addrOrId2, boolean isAddress2) throws RemoteException;
   public int       getThreadHashCode(long addrOrId, boolean isAddress) throws RemoteException;

agent/src/share/classes/sun/jvm/hotspot/debugger/remote/RemoteDebuggerClient.java

@@ -85,9 +85,9 @@ public class RemoteDebuggerClient extends DebuggerBase implements JVMDebugger {
       jlongSize    = remoteDebugger.getJLongSize();
       jshortSize   = remoteDebugger.getJShortSize();
       javaPrimitiveTypesConfigured = true;
-      heapBase     = remoteDebugger.getHeapBase();
+      narrowOopBase  = remoteDebugger.getNarrowOopBase();
+      narrowOopShift = remoteDebugger.getNarrowOopShift();
       heapOopSize  = remoteDebugger.getHeapOopSize();
-      logMinObjAlignmentInBytes  = remoteDebugger.getLogMinObjAlignmentInBytes();
     }
     catch (RemoteException e) {
       throw new DebuggerException(e);

agent/src/share/classes/sun/jvm/hotspot/debugger/remote/RemoteDebuggerServer.java

@@ -114,17 +114,18 @@ public class RemoteDebuggerServer extends UnicastRemoteObject
     return debugger.getJShortSize();
   }
 
-  public long getHeapBase() throws RemoteException {
-    return debugger.getHeapBase();
-  }
-
   public long getHeapOopSize() throws RemoteException {
     return debugger.getHeapOopSize();
   }
 
-  public long getLogMinObjAlignmentInBytes() throws RemoteException {
-    return debugger.getLogMinObjAlignmentInBytes();
+  public long getNarrowOopBase() throws RemoteException {
+    return debugger.getNarrowOopBase();
   }
+
+  public int  getNarrowOopShift() throws RemoteException {
+    return debugger.getNarrowOopShift();
+  }
+
   public boolean   areThreadsEqual(long addrOrId1, boolean isAddress1,
                                    long addrOrId2, boolean isAddress2) throws RemoteException {
     ThreadProxy t1 = getThreadProxy(addrOrId1, isAddress1);

agent/src/share/classes/sun/jvm/hotspot/memory/Universe.java

@@ -53,7 +53,8 @@ public class Universe {
   // system obj array klass object
   private static sun.jvm.hotspot.types.OopField systemObjArrayKlassObjField;
 
-  private static AddressField heapBaseField;
+  private static AddressField narrowOopBaseField;
+  private static CIntegerField narrowOopShiftField;
 
   static {
     VM.registerVMInitializedObserver(new Observer() {
@@ -86,7 +87,8 @@ public class Universe {
 
     systemObjArrayKlassObjField = type.getOopField("_systemObjArrayKlassObj");
 
-    heapBaseField = type.getAddressField("_heap_base");
+    narrowOopBaseField = type.getAddressField("_narrow_oop._base");
+    narrowOopShiftField = type.getCIntegerField("_narrow_oop._shift");
   }
 
   public Universe() {
@@ -100,14 +102,18 @@ public class Universe {
     }
   }
 
-  public static long getHeapBase() {
-    if (heapBaseField.getValue() == null) {
+  public static long getNarrowOopBase() {
+    if (narrowOopBaseField.getValue() == null) {
       return 0;
     } else {
-      return heapBaseField.getValue().minus(null);
+      return narrowOopBaseField.getValue().minus(null);
     }
   }
 
+  public static int getNarrowOopShift() {
+    return (int)narrowOopShiftField.getValue();
+  }
+
   /** Returns "TRUE" iff "p" points into the allocated area of the heap. */
   public boolean isIn(Address p) {
     return heap().isIn(p);

agent/src/share/classes/sun/jvm/hotspot/runtime/VM.java

@@ -342,8 +342,8 @@ public class VM {
       throw new RuntimeException("Attempt to initialize VM twice");
     }
     soleInstance = new VM(db, debugger, debugger.getMachineDescription().isBigEndian());
-    debugger.putHeapConst(Universe.getHeapBase(), soleInstance.getHeapOopSize(),
-                          soleInstance.logMinObjAlignmentInBytes);
+    debugger.putHeapConst(soleInstance.getHeapOopSize(), Universe.getNarrowOopBase(),
+                          Universe.getNarrowOopShift());
     for (Iterator iter = vmInitializedObservers.iterator(); iter.hasNext(); ) {
       ((Observer) iter.next()).update(null, null);
     }

src/cpu/sparc/vm/assembler_sparc.cpp

@@ -4316,7 +4316,13 @@ void MacroAssembler::store_heap_oop(Register d, const Address& a, int offset) {
 
 void MacroAssembler::encode_heap_oop(Register src, Register dst) {
   assert (UseCompressedOops, "must be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
   verify_oop(src);
+  if (Universe::narrow_oop_base() == NULL) {
+    srlx(src, LogMinObjAlignmentInBytes, dst);
+    return;
+  }
   Label done;
   if (src == dst) {
     // optimize for frequent case src == dst
@@ -4338,26 +4344,39 @@ void MacroAssembler::encode_heap_oop(Register src, Register dst) {
 
 void MacroAssembler::encode_heap_oop_not_null(Register r) {
   assert (UseCompressedOops, "must be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
   verify_oop(r);
-  sub(r, G6_heapbase, r);
+  if (Universe::narrow_oop_base() != NULL)
+    sub(r, G6_heapbase, r);
   srlx(r, LogMinObjAlignmentInBytes, r);
 }
 
 void MacroAssembler::encode_heap_oop_not_null(Register src, Register dst) {
   assert (UseCompressedOops, "must be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
   verify_oop(src);
-  sub(src, G6_heapbase, dst);
-  srlx(dst, LogMinObjAlignmentInBytes, dst);
+  if (Universe::narrow_oop_base() == NULL) {
+    srlx(src, LogMinObjAlignmentInBytes, dst);
+  } else {
+    sub(src, G6_heapbase, dst);
+    srlx(dst, LogMinObjAlignmentInBytes, dst);
+  }
 }
 
 // Same algorithm as oops.inline.hpp decode_heap_oop.
 void  MacroAssembler::decode_heap_oop(Register src, Register dst) {
   assert (UseCompressedOops, "must be compressed");
-  Label done;
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
   sllx(src, LogMinObjAlignmentInBytes, dst);
-  bpr(rc_nz, true, Assembler::pt, dst, done);
-  delayed() -> add(dst, G6_heapbase, dst); // annuled if not taken
-  bind(done);
+  if (Universe::narrow_oop_base() != NULL) {
+    Label done;
+    bpr(rc_nz, true, Assembler::pt, dst, done);
+    delayed() -> add(dst, G6_heapbase, dst); // annuled if not taken
+    bind(done);
+  }
   verify_oop(dst);
 }
 
@@ -4366,8 +4385,11 @@ void  MacroAssembler::decode_heap_oop_not_null(Register r) {
   // pd_code_size_limit.
   // Also do not verify_oop as this is called by verify_oop.
   assert (UseCompressedOops, "must be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
   sllx(r, LogMinObjAlignmentInBytes, r);
-  add(r, G6_heapbase, r);
+  if (Universe::narrow_oop_base() != NULL)
+    add(r, G6_heapbase, r);
 }
 
 void  MacroAssembler::decode_heap_oop_not_null(Register src, Register dst) {
@@ -4375,14 +4397,17 @@ void  MacroAssembler::decode_heap_oop_not_null(Register src, Register dst) {
   // pd_code_size_limit.
   // Also do not verify_oop as this is called by verify_oop.
   assert (UseCompressedOops, "must be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
   sllx(src, LogMinObjAlignmentInBytes, dst);
-  add(dst, G6_heapbase, dst);
+  if (Universe::narrow_oop_base() != NULL)
+    add(dst, G6_heapbase, dst);
 }
 
 void MacroAssembler::reinit_heapbase() {
   if (UseCompressedOops) {
     // call indirectly to solve generation ordering problem
-    Address base(G6_heapbase, (address)Universe::heap_base_addr());
+    Address base(G6_heapbase, (address)Universe::narrow_oop_base_addr());
     load_ptr_contents(base, G6_heapbase);
   }
 }

src/cpu/sparc/vm/sparc.ad

@@ -547,7 +547,11 @@ int MachCallDynamicJavaNode::ret_addr_offset() {
     int v_off = entry_offset*wordSize + vtableEntry::method_offset_in_bytes();
     int klass_load_size;
     if (UseCompressedOops) {
-      klass_load_size = 3*BytesPerInstWord; // see MacroAssembler::load_klass()
+      assert(Universe::heap() != NULL, "java heap should be initialized");
+      if (Universe::narrow_oop_base() == NULL)
+        klass_load_size = 2*BytesPerInstWord; // see MacroAssembler::load_klass()
+      else
+        klass_load_size = 3*BytesPerInstWord;
     } else {
       klass_load_size = 1*BytesPerInstWord;
     }
@@ -1601,9 +1605,11 @@ void MachUEPNode::format( PhaseRegAlloc *ra_, outputStream *st ) const {
   st->print_cr("\nUEP:");
 #ifdef    _LP64
   if (UseCompressedOops) {
+    assert(Universe::heap() != NULL, "java heap should be initialized");
     st->print_cr("\tLDUW   [R_O0 + oopDesc::klass_offset_in_bytes],R_G5\t! Inline cache check - compressed klass");
     st->print_cr("\tSLL    R_G5,3,R_G5");
-    st->print_cr("\tADD    R_G5,R_G6_heap_base,R_G5");
+    if (Universe::narrow_oop_base() != NULL)
+      st->print_cr("\tADD    R_G5,R_G6_heap_base,R_G5");
   } else {
     st->print_cr("\tLDX    [R_O0 + oopDesc::klass_offset_in_bytes],R_G5\t! Inline cache check");
   }
@@ -2502,7 +2508,11 @@ encode %{
       __ load_klass(O0, G3_scratch);
       int klass_load_size;
       if (UseCompressedOops) {
-        klass_load_size = 3*BytesPerInstWord;
+        assert(Universe::heap() != NULL, "java heap should be initialized");
+        if (Universe::narrow_oop_base() == NULL)
+          klass_load_size = 2*BytesPerInstWord;
+        else
+          klass_load_size = 3*BytesPerInstWord;
       } else {
         klass_load_size = 1*BytesPerInstWord;
       }

src/cpu/sparc/vm/stubGenerator_sparc.cpp

@@ -2942,14 +2942,15 @@ class StubGenerator: public StubCodeGenerator {
     StubRoutines::_atomic_add_ptr_entry      = StubRoutines::_atomic_add_entry;
     StubRoutines::_fence_entry               = generate_fence();
 #endif  // COMPILER2 !=> _LP64
-
-    StubRoutines::Sparc::_partial_subtype_check                = generate_partial_subtype_check();
   }
 
 
   void generate_all() {
     // Generates all stubs and initializes the entry points
 
+    // Generate partial_subtype_check first here since its code depends on
+    // UseZeroBaseCompressedOops which is defined after heap initialization.
+    StubRoutines::Sparc::_partial_subtype_check                = generate_partial_subtype_check();
     // These entry points require SharedInfo::stack0 to be set up in non-core builds
     StubRoutines::_throw_AbstractMethodError_entry         = generate_throw_exception("AbstractMethodError throw_exception",          CAST_FROM_FN_PTR(address, SharedRuntime::throw_AbstractMethodError),  false);
     StubRoutines::_throw_IncompatibleClassChangeError_entry= generate_throw_exception("IncompatibleClassChangeError throw_exception", CAST_FROM_FN_PTR(address, SharedRuntime::throw_IncompatibleClassChangeError),  false);

src/cpu/sparc/vm/vm_version_sparc.cpp

@@ -72,6 +72,9 @@ void VM_Version::initialize() {
         FLAG_SET_ERGO(bool, UseCompressedOops, false);
       }
     }
+    // 32-bit oops don't make sense for the 64-bit VM on sparc
+    // since the 32-bit VM has the same registers and smaller objects.
+    Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
 #endif // _LP64
 #ifdef COMPILER2
     // Indirect branch is the same cost as direct

src/cpu/sparc/vm/vtableStubs_sparc.cpp

@@ -221,13 +221,15 @@ int VtableStub::pd_code_size_limit(bool is_vtable_stub) {
     if (is_vtable_stub) {
       // ld;ld;ld,jmp,nop
       const int basic = 5*BytesPerInstWord +
-                        // shift;add for load_klass
-                        (UseCompressedOops ? 2*BytesPerInstWord : 0);
+                        // shift;add for load_klass (only shift with zero heap based)
+                        (UseCompressedOops ?
+                         ((Universe::narrow_oop_base() == NULL) ? BytesPerInstWord : 2*BytesPerInstWord) : 0);
       return basic + slop;
     } else {
       const int basic = (28 LP64_ONLY(+ 6)) * BytesPerInstWord +
-                        // shift;add for load_klass
-                        (UseCompressedOops ? 2*BytesPerInstWord : 0);
+                        // shift;add for load_klass (only shift with zero heap based)
+                        (UseCompressedOops ?
+                         ((Universe::narrow_oop_base() == NULL) ? BytesPerInstWord : 2*BytesPerInstWord) : 0);
       return (basic + slop);
     }
   }

src/cpu/x86/vm/assembler_x86.cpp

@@ -727,7 +727,7 @@ address Assembler::locate_operand(address inst, WhichOperand which) {
   }
 
 #ifdef _LP64
-  assert(false, "fix locate_operand");
+  assert(which == narrow_oop_operand && !is_64bit, "instruction is not a movl adr, imm32");
 #else
   assert(which == imm_operand, "instruction has only an imm field");
 #endif // LP64
@@ -3224,12 +3224,6 @@ void Assembler::fyl2x() {
   emit_byte(0xF1);
 }
 
-void Assembler::mov_literal32(Register dst, int32_t imm32, RelocationHolder const& rspec, int format) {
-  InstructionMark im(this);
-  int encode = prefix_and_encode(dst->encoding());
-  emit_byte(0xB8 | encode);
-  emit_data((int)imm32, rspec, format);
-}
 
 #ifndef _LP64
 
@@ -3249,6 +3243,12 @@ void Assembler::mov_literal32(Address dst, int32_t imm32,  RelocationHolder cons
   emit_data((int)imm32, rspec, 0);
 }
 
+void Assembler::mov_literal32(Register dst, int32_t imm32, RelocationHolder const& rspec) {
+  InstructionMark im(this);
+  int encode = prefix_and_encode(dst->encoding());
+  emit_byte(0xB8 | encode);
+  emit_data((int)imm32, rspec, 0);
+}
 
 void Assembler::popa() { // 32bit
   emit_byte(0x61);
@@ -3857,6 +3857,37 @@ void Assembler::mov_literal64(Register dst, intptr_t imm64, RelocationHolder con
   emit_data64(imm64, rspec);
 }
 
+void Assembler::mov_narrow_oop(Register dst, int32_t imm32, RelocationHolder const& rspec) {
+  InstructionMark im(this);
+  int encode = prefix_and_encode(dst->encoding());
+  emit_byte(0xB8 | encode);
+  emit_data((int)imm32, rspec, narrow_oop_operand);
+}
+
+void Assembler::mov_narrow_oop(Address dst, int32_t imm32,  RelocationHolder const& rspec) {
+  InstructionMark im(this);
+  prefix(dst);
+  emit_byte(0xC7);
+  emit_operand(rax, dst, 4);
+  emit_data((int)imm32, rspec, narrow_oop_operand);
+}
+
+void Assembler::cmp_narrow_oop(Register src1, int32_t imm32, RelocationHolder const& rspec) {
+  InstructionMark im(this);
+  int encode = prefix_and_encode(src1->encoding());
+  emit_byte(0x81);
+  emit_byte(0xF8 | encode);
+  emit_data((int)imm32, rspec, narrow_oop_operand);
+}
+
+void Assembler::cmp_narrow_oop(Address src1, int32_t imm32, RelocationHolder const& rspec) {
+  InstructionMark im(this);
+  prefix(src1);
+  emit_byte(0x81);
+  emit_operand(rax, src1, 4);
+  emit_data((int)imm32, rspec, narrow_oop_operand);
+}
+
 void Assembler::movdq(XMMRegister dst, Register src) {
   // table D-1 says MMX/SSE2
   NOT_LP64(assert(VM_Version::supports_sse2() || VM_Version::supports_mmx(), ""));
@@ -7710,14 +7741,21 @@ void MacroAssembler::load_klass(Register dst, Register src) {
 void MacroAssembler::load_prototype_header(Register dst, Register src) {
 #ifdef _LP64
   if (UseCompressedOops) {
+    assert (Universe::heap() != NULL, "java heap should be initialized");
     movl(dst, Address(src, oopDesc::klass_offset_in_bytes()));
-    movq(dst, Address(r12_heapbase, dst, Address::times_8, Klass::prototype_header_offset_in_bytes() + klassOopDesc::klass_part_offset_in_bytes()));
+    if (Universe::narrow_oop_shift() != 0) {
+      assert(Address::times_8 == LogMinObjAlignmentInBytes &&
+             Address::times_8 == Universe::narrow_oop_shift(), "decode alg wrong");
+      movq(dst, Address(r12_heapbase, dst, Address::times_8, Klass::prototype_header_offset_in_bytes() + klassOopDesc::klass_part_offset_in_bytes()));
+    } else {
+      movq(dst, Address(dst, Klass::prototype_header_offset_in_bytes() + klassOopDesc::klass_part_offset_in_bytes()));
+    }
   } else
 #endif
-    {
-      movptr(dst, Address(src, oopDesc::klass_offset_in_bytes()));
-      movptr(dst, Address(dst, Klass::prototype_header_offset_in_bytes() + klassOopDesc::klass_part_offset_in_bytes()));
-    }
+  {
+    movptr(dst, Address(src, oopDesc::klass_offset_in_bytes()));
+    movptr(dst, Address(dst, Klass::prototype_header_offset_in_bytes() + klassOopDesc::klass_part_offset_in_bytes()));
+  }
 }
 
 void MacroAssembler::store_klass(Register dst, Register src) {
@@ -7760,11 +7798,20 @@ void MacroAssembler::store_heap_oop(Address dst, Register src) {
 // Algorithm must match oop.inline.hpp encode_heap_oop.
 void MacroAssembler::encode_heap_oop(Register r) {
   assert (UseCompressedOops, "should be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  if (Universe::narrow_oop_base() == NULL) {
+    verify_oop(r, "broken oop in encode_heap_oop");
+    if (Universe::narrow_oop_shift() != 0) {
+      assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
+      shrq(r, LogMinObjAlignmentInBytes);
+    }
+    return;
+  }
 #ifdef ASSERT
   if (CheckCompressedOops) {
     Label ok;
     push(rscratch1); // cmpptr trashes rscratch1
-    cmpptr(r12_heapbase, ExternalAddress((address)Universe::heap_base_addr()));
+    cmpptr(r12_heapbase, ExternalAddress((address)Universe::narrow_oop_base_addr()));
     jcc(Assembler::equal, ok);
     stop("MacroAssembler::encode_heap_oop: heap base corrupted?");
     bind(ok);
@@ -7780,6 +7827,7 @@ void MacroAssembler::encode_heap_oop(Register r) {
 
 void MacroAssembler::encode_heap_oop_not_null(Register r) {
   assert (UseCompressedOops, "should be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
 #ifdef ASSERT
   if (CheckCompressedOops) {
     Label ok;
@@ -7790,12 +7838,18 @@ void MacroAssembler::encode_heap_oop_not_null(Register r) {
   }
 #endif
   verify_oop(r, "broken oop in encode_heap_oop_not_null");
-  subq(r, r12_heapbase);
-  shrq(r, LogMinObjAlignmentInBytes);
+  if (Universe::narrow_oop_base() != NULL) {
+    subq(r, r12_heapbase);
+  }
+  if (Universe::narrow_oop_shift() != 0) {
+    assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
+    shrq(r, LogMinObjAlignmentInBytes);
+  }
 }
 
 void MacroAssembler::encode_heap_oop_not_null(Register dst, Register src) {
   assert (UseCompressedOops, "should be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
 #ifdef ASSERT
   if (CheckCompressedOops) {
     Label ok;
@@ -7809,18 +7863,32 @@ void MacroAssembler::encode_heap_oop_not_null(Register dst, Register src) {
   if (dst != src) {
     movq(dst, src);
   }
-  subq(dst, r12_heapbase);
-  shrq(dst, LogMinObjAlignmentInBytes);
+  if (Universe::narrow_oop_base() != NULL) {
+    subq(dst, r12_heapbase);
+  }
+  if (Universe::narrow_oop_shift() != 0) {
+    assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
+    shrq(dst, LogMinObjAlignmentInBytes);
+  }
 }
 
 void  MacroAssembler::decode_heap_oop(Register r) {
   assert (UseCompressedOops, "should be compressed");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  if (Universe::narrow_oop_base() == NULL) {
+    if (Universe::narrow_oop_shift() != 0) {
+      assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
+      shlq(r, LogMinObjAlignmentInBytes);
+    }
+    verify_oop(r, "broken oop in decode_heap_oop");
+    return;
+  }
 #ifdef ASSERT
   if (CheckCompressedOops) {
     Label ok;
     push(rscratch1);
     cmpptr(r12_heapbase,
-           ExternalAddress((address)Universe::heap_base_addr()));
+           ExternalAddress((address)Universe::narrow_oop_base_addr()));
     jcc(Assembler::equal, ok);
     stop("MacroAssembler::decode_heap_oop: heap base corrupted?");
     bind(ok);
@@ -7844,32 +7912,76 @@ void  MacroAssembler::decode_heap_oop(Register r) {
 
 void  MacroAssembler::decode_heap_oop_not_null(Register r) {
   assert (UseCompressedOops, "should only be used for compressed headers");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
   // Cannot assert, unverified entry point counts instructions (see .ad file)
   // vtableStubs also counts instructions in pd_code_size_limit.
   // Also do not verify_oop as this is called by verify_oop.
-  assert(Address::times_8 == LogMinObjAlignmentInBytes, "decode alg wrong");
-  leaq(r, Address(r12_heapbase, r, Address::times_8, 0));
+  if (Universe::narrow_oop_base() == NULL) {
+    if (Universe::narrow_oop_shift() != 0) {
+      assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
+      shlq(r, LogMinObjAlignmentInBytes);
+    }
+  } else {
+      assert (Address::times_8 == LogMinObjAlignmentInBytes &&
+              Address::times_8 == Universe::narrow_oop_shift(), "decode alg wrong");
+    leaq(r, Address(r12_heapbase, r, Address::times_8, 0));
+  }
 }
 
 void  MacroAssembler::decode_heap_oop_not_null(Register dst, Register src) {
   assert (UseCompressedOops, "should only be used for compressed headers");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
   // Cannot assert, unverified entry point counts instructions (see .ad file)
   // vtableStubs also counts instructions in pd_code_size_limit.
   // Also do not verify_oop as this is called by verify_oop.
-  assert(Address::times_8 == LogMinObjAlignmentInBytes, "decode alg wrong");
-  leaq(dst, Address(r12_heapbase, src, Address::times_8, 0));
+  if (Universe::narrow_oop_shift() != 0) {
+    assert (Address::times_8 == LogMinObjAlignmentInBytes &&
+            Address::times_8 == Universe::narrow_oop_shift(), "decode alg wrong");
+    leaq(dst, Address(r12_heapbase, src, Address::times_8, 0));
+  } else if (dst != src) {
+    movq(dst, src);
+  }
 }
 
 void  MacroAssembler::set_narrow_oop(Register dst, jobject obj) {
-  assert(oop_recorder() != NULL, "this assembler needs an OopRecorder");
+  assert (UseCompressedOops, "should only be used for compressed headers");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (oop_recorder() != NULL, "this assembler needs an OopRecorder");
+  int oop_index = oop_recorder()->find_index(obj);
+  RelocationHolder rspec = oop_Relocation::spec(oop_index);
+  mov_narrow_oop(dst, oop_index, rspec);
+}
+
+void  MacroAssembler::set_narrow_oop(Address dst, jobject obj) {
+  assert (UseCompressedOops, "should only be used for compressed headers");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (oop_recorder() != NULL, "this assembler needs an OopRecorder");
+  int oop_index = oop_recorder()->find_index(obj);
+  RelocationHolder rspec = oop_Relocation::spec(oop_index);
+  mov_narrow_oop(dst, oop_index, rspec);
+}
+
+void  MacroAssembler::cmp_narrow_oop(Register dst, jobject obj) {
+  assert (UseCompressedOops, "should only be used for compressed headers");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (oop_recorder() != NULL, "this assembler needs an OopRecorder");
+  int oop_index = oop_recorder()->find_index(obj);
+  RelocationHolder rspec = oop_Relocation::spec(oop_index);
+  Assembler::cmp_narrow_oop(dst, oop_index, rspec);
+}
+
+void  MacroAssembler::cmp_narrow_oop(Address dst, jobject obj) {
+  assert (UseCompressedOops, "should only be used for compressed headers");
+  assert (Universe::heap() != NULL, "java heap should be initialized");
+  assert (oop_recorder() != NULL, "this assembler needs an OopRecorder");
   int oop_index = oop_recorder()->find_index(obj);
   RelocationHolder rspec = oop_Relocation::spec(oop_index);
-  mov_literal32(dst, oop_index, rspec, narrow_oop_operand);
+  Assembler::cmp_narrow_oop(dst, oop_index, rspec);
 }
 
 void MacroAssembler::reinit_heapbase() {
   if (UseCompressedOops) {
-    movptr(r12_heapbase, ExternalAddress((address)Universe::heap_base_addr()));
+    movptr(r12_heapbase, ExternalAddress((address)Universe::narrow_oop_base_addr()));
   }
 }
 #endif // _LP64

src/cpu/x86/vm/assembler_x86.hpp

@@ -578,20 +578,25 @@ private:
 
   // These are all easily abused and hence protected
 
-  void mov_literal32(Register dst, int32_t imm32, RelocationHolder const& rspec, int format = 0);
-
   // 32BIT ONLY SECTION
 #ifndef _LP64
   // Make these disappear in 64bit mode since they would never be correct
   void cmp_literal32(Register src1, int32_t imm32, RelocationHolder const& rspec);   // 32BIT ONLY
   void cmp_literal32(Address src1, int32_t imm32, RelocationHolder const& rspec);    // 32BIT ONLY
 
+  void mov_literal32(Register dst, int32_t imm32, RelocationHolder const& rspec);    // 32BIT ONLY
   void mov_literal32(Address dst, int32_t imm32, RelocationHolder const& rspec);     // 32BIT ONLY
 
   void push_literal32(int32_t imm32, RelocationHolder const& rspec);                 // 32BIT ONLY
 #else
   // 64BIT ONLY SECTION
   void mov_literal64(Register dst, intptr_t imm64, RelocationHolder const& rspec);   // 64BIT ONLY
+
+  void cmp_narrow_oop(Register src1, int32_t imm32, RelocationHolder const& rspec);
+  void cmp_narrow_oop(Address src1, int32_t imm32, RelocationHolder const& rspec);
+
+  void mov_narrow_oop(Register dst, int32_t imm32, RelocationHolder const& rspec);
+  void mov_narrow_oop(Address dst, int32_t imm32, RelocationHolder const& rspec);
 #endif // _LP64
 
   // These are unique in that we are ensured by the caller that the 32bit
@@ -1647,6 +1652,9 @@ class MacroAssembler: public Assembler {
   void decode_heap_oop_not_null(Register dst, Register src);
 
   void set_narrow_oop(Register dst, jobject obj);
+  void set_narrow_oop(Address dst, jobject obj);
+  void cmp_narrow_oop(Register dst, jobject obj);
+  void cmp_narrow_oop(Address dst, jobject obj);
 
   // if heap base register is used - reinit it with the correct value
   void reinit_heapbase();

src/os/linux/vm/os_linux.cpp

@@ -2582,7 +2582,7 @@ bool os::large_page_init() {
 #define SHM_HUGETLB 04000
 #endif
 
-char* os::reserve_memory_special(size_t bytes) {
+char* os::reserve_memory_special(size_t bytes, char* req_addr) {
   assert(UseLargePages, "only for large pages");
 
   key_t key = IPC_PRIVATE;

src/os/solaris/dtrace/generateJvmOffsets.cpp

@@ -249,6 +249,10 @@ int generateJvmOffsets(GEN_variant gen_variant) {
 
   printf("\n");
 
+  GEN_OFFS(NarrowOopStruct, _base);
+  GEN_OFFS(NarrowOopStruct, _shift);
+  printf("\n");
+
   GEN_VALUE(SIZE_HeapBlockHeader, sizeof(HeapBlock::Header));
   GEN_SIZE(oopDesc);
   GEN_SIZE(constantPoolOopDesc);

src/os/solaris/dtrace/jhelper.d

@@ -46,7 +46,10 @@ extern pointer __JvmOffsets;
 extern pointer __1cJCodeCacheF_heap_;
 extern pointer __1cIUniverseP_methodKlassObj_;
 extern pointer __1cIUniverseO_collectedHeap_;
-extern pointer __1cIUniverseK_heap_base_;
+extern pointer __1cIUniverseL_narrow_oop_;
+#ifdef _LP64
+extern pointer UseCompressedOops;
+#endif
 
 extern pointer __1cHnmethodG__vtbl_;
 extern pointer __1cKBufferBlobG__vtbl_;
@@ -56,6 +59,7 @@ extern pointer __1cKBufferBlobG__vtbl_;
 #define copyin_uint16(ADDR) *(uint16_t*) copyin((pointer) (ADDR), sizeof(uint16_t))
 #define copyin_uint32(ADDR) *(uint32_t*) copyin((pointer) (ADDR), sizeof(uint32_t))
 #define copyin_int32(ADDR)  *(int32_t*)  copyin((pointer) (ADDR), sizeof(int32_t))
+#define copyin_uint8(ADDR)  *(uint8_t*)  copyin((pointer) (ADDR), sizeof(uint8_t))
 
 #define SAME(x) x
 #define copyin_offset(JVM_CONST)  JVM_CONST = \
@@ -132,6 +136,9 @@ dtrace:helper:ustack:
   copyin_offset(SIZE_oopDesc);
   copyin_offset(SIZE_constantPoolOopDesc);
 
+  copyin_offset(OFFSET_NarrowOopStruct_base);
+  copyin_offset(OFFSET_NarrowOopStruct_shift);
+
   /*
    * The PC to translate is in arg0.
    */
@@ -151,9 +158,19 @@ dtrace:helper:ustack:
 
   this->Universe_methodKlassOop = copyin_ptr(&``__1cIUniverseP_methodKlassObj_);
   this->CodeCache_heap_address = copyin_ptr(&``__1cJCodeCacheF_heap_);
-  this->Universe_heap_base = copyin_ptr(&``__1cIUniverseK_heap_base_);
 
   /* Reading volatile values */
+#ifdef _LP64
+  this->Use_Compressed_Oops  = copyin_uint8(&``UseCompressedOops);
+#else
+  this->Use_Compressed_Oops  = 0;
+#endif
+
+  this->Universe_narrow_oop_base  = copyin_ptr(&``__1cIUniverseL_narrow_oop_ +
+                                               OFFSET_NarrowOopStruct_base);
+  this->Universe_narrow_oop_shift = copyin_int32(&``__1cIUniverseL_narrow_oop_ +
+                                                 OFFSET_NarrowOopStruct_shift);
+
   this->CodeCache_low = copyin_ptr(this->CodeCache_heap_address + 
       OFFSET_CodeHeap_memory + OFFSET_VirtualSpace_low);
 
@@ -295,7 +312,7 @@ dtrace:helper:ustack:
 
 dtrace:helper:ustack:
 /!this->done && this->vtbl == this->BufferBlob_vtbl &&
-this->Universe_heap_base == NULL &&
+this->Use_Compressed_Oops == 0 &&
 this->methodOopPtr > this->heap_start && this->methodOopPtr < this->heap_end/
 {
   MARK_LINE;
@@ -306,7 +323,7 @@ this->methodOopPtr > this->heap_start && this->methodOopPtr < this->heap_end/
 
 dtrace:helper:ustack:
 /!this->done && this->vtbl == this->BufferBlob_vtbl &&
-this->Universe_heap_base != NULL &&
+this->Use_Compressed_Oops != 0 &&
 this->methodOopPtr > this->heap_start && this->methodOopPtr < this->heap_end/
 {
   MARK_LINE;
@@ -314,8 +331,8 @@ this->methodOopPtr > this->heap_start && this->methodOopPtr < this->heap_end/
    * Read compressed pointer and  decode heap oop, same as oop.inline.hpp
    */
   this->cklass = copyin_uint32(this->methodOopPtr + OFFSET_oopDesc_metadata);
-  this->klass = (uint64_t)((uintptr_t)this->Universe_heap_base +
-                ((uintptr_t)this->cklass << 3));
+  this->klass = (uint64_t)((uintptr_t)this->Universe_narrow_oop_base +
+                ((uintptr_t)this->cklass << this->Universe_narrow_oop_shift));
   this->methodOop = this->klass == this->Universe_methodKlassOop;
   this->done = !this->methodOop;
 }

src/os/solaris/dtrace/libjvm_db.c

@@ -146,13 +146,17 @@ struct jvm_agent {
   uint64_t BufferBlob_vtbl;
   uint64_t RuntimeStub_vtbl;
 
+  uint64_t Use_Compressed_Oops_address;
   uint64_t Universe_methodKlassObj_address;
+  uint64_t Universe_narrow_oop_base_address;
+  uint64_t Universe_narrow_oop_shift_address;
   uint64_t CodeCache_heap_address;
-  uint64_t Universe_heap_base_address;
 
   /* Volatiles */
+  uint8_t  Use_Compressed_Oops;
   uint64_t Universe_methodKlassObj;
-  uint64_t Universe_heap_base;
+  uint64_t Universe_narrow_oop_base;
+  uint32_t Universe_narrow_oop_shift;
   uint64_t CodeCache_low;
   uint64_t CodeCache_high;
   uint64_t CodeCache_segmap_low;
@@ -279,8 +283,11 @@ static int parse_vmstructs(jvm_agent_t* J) {
       if (strcmp("_methodKlassObj", vmp->fieldName) == 0) {
         J->Universe_methodKlassObj_address = vmp->address;
       }
-      if (strcmp("_heap_base", vmp->fieldName) == 0) {
-        J->Universe_heap_base_address = vmp->address;
+      if (strcmp("_narrow_oop._base", vmp->fieldName) == 0) {
+        J->Universe_narrow_oop_base_address = vmp->address;
+      }
+      if (strcmp("_narrow_oop._shift", vmp->fieldName) == 0) {
+        J->Universe_narrow_oop_shift_address = vmp->address;
       }
     }
     CHECK_FAIL(err);
@@ -298,14 +305,39 @@ static int parse_vmstructs(jvm_agent_t* J) {
   return -1;
 }
 
+static int find_symbol(jvm_agent_t* J, const char *name, uint64_t* valuep) {
+  psaddr_t sym_addr;
+  int err;
+
+  err = ps_pglobal_lookup(J->P, LIBJVM_SO, name, &sym_addr);
+  if (err != PS_OK) goto fail;
+  *valuep = sym_addr;
+  return PS_OK;
+
+ fail:
+  return err;
+}
+
 static int read_volatiles(jvm_agent_t* J) {
   uint64_t ptr;
   int err;
 
+  err = find_symbol(J, "UseCompressedOops", &J->Use_Compressed_Oops_address);
+  if (err == PS_OK) {
+    err = ps_pread(J->P,  J->Use_Compressed_Oops_address, &J->Use_Compressed_Oops, sizeof(uint8_t));
+    CHECK_FAIL(err);
+  } else {
+    J->Use_Compressed_Oops = 0;
+  }
+
   err = read_pointer(J, J->Universe_methodKlassObj_address, &J->Universe_methodKlassObj);
   CHECK_FAIL(err);
-  err = read_pointer(J, J->Universe_heap_base_address, &J->Universe_heap_base);
+
+  err = read_pointer(J, J->Universe_narrow_oop_base_address, &J->Universe_narrow_oop_base);
+  CHECK_FAIL(err);
+  err = ps_pread(J->P,  J->Universe_narrow_oop_shift_address, &J->Universe_narrow_oop_shift, sizeof(uint32_t));
   CHECK_FAIL(err);
+
   err = read_pointer(J, J->CodeCache_heap_address + OFFSET_CodeHeap_memory +
                      OFFSET_VirtualSpace_low, &J->CodeCache_low);
   CHECK_FAIL(err);
@@ -374,19 +406,6 @@ static int find_start(jvm_agent_t* J, uint64_t ptr, uint64_t *startp) {
   return -1;
 }
 
-static int find_symbol(jvm_agent_t* J, const char *name, uint64_t* valuep) {
-  psaddr_t sym_addr;
-  int err;
-
-  err = ps_pglobal_lookup(J->P, LIBJVM_SO, name, &sym_addr);
-  if (err != PS_OK) goto fail;
-  *valuep = sym_addr;
-  return PS_OK;
-
- fail:
-  return err;
-}
-
 static int find_jlong_constant(jvm_agent_t* J, const char *name, uint64_t* valuep) {
   psaddr_t sym_addr;
   int err = ps_pglobal_lookup(J->P, LIBJVM_SO, name, &sym_addr);
@@ -458,14 +477,14 @@ void Jagent_destroy(jvm_agent_t *J) {
 static int is_methodOop(jvm_agent_t* J, uint64_t methodOopPtr) {
   uint64_t klass;
   int err;
-  // If heap_base is nonnull, this was a compressed oop.
-  if (J->Universe_heap_base != NULL) {
+  // If UseCompressedOops, this was a compressed oop.
+  if (J->Use_Compressed_Oops != 0) {
     uint32_t cklass;
     err = read_compressed_pointer(J, methodOopPtr + OFFSET_oopDesc_metadata,
           &cklass);
     // decode heap oop, same as oop.inline.hpp
-    klass = (uint64_t)((uintptr_t)J->Universe_heap_base +
-            ((uintptr_t)cklass << 3));
+    klass = (uint64_t)((uintptr_t)J->Universe_narrow_oop_base +
+            ((uintptr_t)cklass << J->Universe_narrow_oop_shift));
   } else {
     err = read_pointer(J, methodOopPtr + OFFSET_oopDesc_metadata, &klass);
   }

src/os/solaris/vm/os_solaris.cpp

@@ -3220,7 +3220,7 @@ bool os::Solaris::set_mpss_range(caddr_t start, size_t bytes, size_t align) {
   return true;
 }
 
-char* os::reserve_memory_special(size_t bytes) {
+char* os::reserve_memory_special(size_t bytes, char* addr) {
   assert(UseLargePages && UseISM, "only for ISM large pages");
 
   size_t size = bytes;

src/os/windows/vm/os_windows.cpp

@@ -2595,7 +2595,7 @@ bool os::can_execute_large_page_memory() {
   return true;
 }
 
-char* os::reserve_memory_special(size_t bytes) {
+char* os::reserve_memory_special(size_t bytes, char* addr) {
 
   if (UseLargePagesIndividualAllocation) {
     if (TracePageSizes && Verbose) {
@@ -2615,7 +2615,7 @@ char* os::reserve_memory_special(size_t bytes) {
         "use -XX:-UseLargePagesIndividualAllocation to turn off");
       return NULL;
     }
-    p_buf = (char *) VirtualAlloc(NULL,
+    p_buf = (char *) VirtualAlloc(addr,
                                  size_of_reserve,  // size of Reserve
                                  MEM_RESERVE,
                                  PAGE_EXECUTE_READWRITE);

src/os_cpu/linux_sparc/vm/globals_linux_sparc.hpp

@@ -30,5 +30,7 @@
 define_pd_global(uintx, JVMInvokeMethodSlack,    12288);
 define_pd_global(intx, CompilerThreadStackSize,  0);
 
+// Only used on 64 bit platforms
+define_pd_global(uintx, HeapBaseMinAddress,      4*G);
 // Only used on 64 bit Windows platforms
 define_pd_global(bool, UseVectoredExceptions, false);

src/os_cpu/linux_x86/vm/globals_linux_x86.hpp

@@ -43,5 +43,7 @@ define_pd_global(intx, SurvivorRatio,            8);
 
 define_pd_global(uintx, JVMInvokeMethodSlack,    8192);
 
+// Only used on 64 bit platforms
+define_pd_global(uintx, HeapBaseMinAddress,      2*G);
 // Only used on 64 bit Windows platforms
 define_pd_global(bool, UseVectoredExceptions,    false);

src/os_cpu/solaris_sparc/vm/globals_solaris_sparc.hpp

@@ -30,5 +30,9 @@
 define_pd_global(uintx, JVMInvokeMethodSlack,    12288);
 define_pd_global(intx, CompilerThreadStackSize,  0);
 
+// Only used on 64 bit platforms
+define_pd_global(uintx, HeapBaseMinAddress,      4*G);
 // Only used on 64 bit Windows platforms
 define_pd_global(bool, UseVectoredExceptions,    false);
+
+

src/os_cpu/solaris_x86/vm/globals_solaris_x86.hpp

@@ -46,5 +46,7 @@ define_pd_global(uintx, JVMInvokeMethodSlack,    10*K);
 
 define_pd_global(intx, CompilerThreadStackSize,  0);
 
+// Only used on 64 bit platforms
+define_pd_global(uintx, HeapBaseMinAddress,      256*M);
 // Only used on 64 bit Windows platforms
 define_pd_global(bool, UseVectoredExceptions,    false);

src/os_cpu/windows_x86/vm/globals_windows_x86.hpp

@@ -45,5 +45,7 @@ define_pd_global(intx, CompilerThreadStackSize,  0);
 
 define_pd_global(uintx, JVMInvokeMethodSlack,    8192);
 
+// Only used on 64 bit platforms
+define_pd_global(uintx, HeapBaseMinAddress,      2*G);
 // Only used on 64 bit Windows platforms
 define_pd_global(bool, UseVectoredExceptions,    false);

src/share/vm/asm/assembler.cpp

@@ -321,16 +321,19 @@ void AbstractAssembler::block_comment(const char* comment) {
 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
   // Exception handler checks the nmethod's implicit null checks table
   // only when this method returns false.
-  if (UseCompressedOops) {
+#ifdef _LP64
+  if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
+    assert (Universe::heap() != NULL, "java heap should be initialized");
     // The first page after heap_base is unmapped and
     // the 'offset' is equal to [heap_base + offset] for
     // narrow oop implicit null checks.
-    uintptr_t heap_base = (uintptr_t)Universe::heap_base();
-    if ((uintptr_t)offset >= heap_base) {
+    uintptr_t base = (uintptr_t)Universe::narrow_oop_base();
+    if ((uintptr_t)offset >= base) {
       // Normalize offset for the next check.
-      offset = (intptr_t)(pointer_delta((void*)offset, (void*)heap_base, 1));
+      offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
     }
   }
+#endif
   return offset < 0 || os::vm_page_size() <= offset;
 }
 

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -1360,9 +1360,34 @@ jint G1CollectedHeap::initialize() {
   // Reserve the maximum.
   PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
   // Includes the perm-gen.
+
+  const size_t total_reserved = max_byte_size + pgs->max_size();
+  char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
+
   ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
                         HeapRegion::GrainBytes,
-                        false /*ism*/);
+                        false /*ism*/, addr);
+
+  if (UseCompressedOops) {
+    if (addr != NULL && !heap_rs.is_reserved()) {
+      // Failed to reserve at specified address - the requested memory
+      // region is taken already, for example, by 'java' launcher.
+      // Try again to reserver heap higher.
+      addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
+      ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
+                             false /*ism*/, addr);
+      if (addr != NULL && !heap_rs0.is_reserved()) {
+        // Failed to reserve at specified address again - give up.
+        addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
+        assert(addr == NULL, "");
+        ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
+                               false /*ism*/, addr);
+        heap_rs = heap_rs1;
+      } else {
+        heap_rs = heap_rs0;
+      }
+    }
+  }
 
   if (!heap_rs.is_reserved()) {
     vm_exit_during_initialization("Could not reserve enough space for object heap");

src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp

@@ -104,12 +104,38 @@ jint ParallelScavengeHeap::initialize() {
                   og_min_size, og_max_size,
                   yg_min_size, yg_max_size);
 
+  const size_t total_reserved = pg_max_size + og_max_size + yg_max_size;
+  char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
+
   // The main part of the heap (old gen + young gen) can often use a larger page
   // size than is needed or wanted for the perm gen.  Use the "compound
   // alignment" ReservedSpace ctor to avoid having to use the same page size for
   // all gens.
+
   ReservedHeapSpace heap_rs(pg_max_size, pg_align, og_max_size + yg_max_size,
-                            og_align);
+                            og_align, addr);
+
+  if (UseCompressedOops) {
+    if (addr != NULL && !heap_rs.is_reserved()) {
+      // Failed to reserve at specified address - the requested memory
+      // region is taken already, for example, by 'java' launcher.
+      // Try again to reserver heap higher.
+      addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
+      ReservedHeapSpace heap_rs0(pg_max_size, pg_align, og_max_size + yg_max_size,
+                                 og_align, addr);
+      if (addr != NULL && !heap_rs0.is_reserved()) {
+        // Failed to reserve at specified address again - give up.
+        addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
+        assert(addr == NULL, "");
+        ReservedHeapSpace heap_rs1(pg_max_size, pg_align, og_max_size + yg_max_size,
+                                   og_align, addr);
+        heap_rs = heap_rs1;
+      } else {
+        heap_rs = heap_rs0;
+      }
+    }
+  }
+
   os::trace_page_sizes("ps perm", pg_min_size, pg_max_size, pg_page_sz,
                        heap_rs.base(), pg_max_size);
   os::trace_page_sizes("ps main", og_min_size + yg_min_size,

src/share/vm/memory/genCollectedHeap.cpp

@@ -218,6 +218,31 @@ char* GenCollectedHeap::allocate(size_t alignment,
     heap_address -= total_reserved;
   } else {
     heap_address = NULL;  // any address will do.
+    if (UseCompressedOops) {
+      heap_address = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
+      *_total_reserved = total_reserved;
+      *_n_covered_regions = n_covered_regions;
+      *heap_rs = ReservedHeapSpace(total_reserved, alignment,
+                                   UseLargePages, heap_address);
+
+      if (heap_address != NULL && !heap_rs->is_reserved()) {
+        // Failed to reserve at specified address - the requested memory
+        // region is taken already, for example, by 'java' launcher.
+        // Try again to reserver heap higher.
+        heap_address = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
+        *heap_rs = ReservedHeapSpace(total_reserved, alignment,
+                                     UseLargePages, heap_address);
+
+        if (heap_address != NULL && !heap_rs->is_reserved()) {
+          // Failed to reserve at specified address again - give up.
+          heap_address = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
+          assert(heap_address == NULL, "");
+          *heap_rs = ReservedHeapSpace(total_reserved, alignment,
+                                       UseLargePages, heap_address);
+        }
+      }
+      return heap_address;
+    }
   }
 
   *_total_reserved = total_reserved;

src/share/vm/memory/universe.cpp

@@ -99,7 +99,8 @@ size_t          Universe::_heap_capacity_at_last_gc;
 size_t          Universe::_heap_used_at_last_gc = 0;
 
 CollectedHeap*  Universe::_collectedHeap = NULL;
-address         Universe::_heap_base = NULL;
+
+NarrowOopStruct Universe::_narrow_oop = { NULL, 0, true };
 
 
 void Universe::basic_type_classes_do(void f(klassOop)) {
@@ -729,6 +730,53 @@ jint universe_init() {
   return JNI_OK;
 }
 
+// Choose the heap base address and oop encoding mode
+// when compressed oops are used:
+// Unscaled  - Use 32-bits oops without encoding when
+//     NarrowOopHeapBaseMin + heap_size < 4Gb
+// ZeroBased - Use zero based compressed oops with encoding when
+//     NarrowOopHeapBaseMin + heap_size < 32Gb
+// HeapBased - Use compressed oops with heap base + encoding.
+
+// 4Gb
+static const uint64_t NarrowOopHeapMax = (uint64_t(max_juint) + 1);
+// 32Gb
+static const uint64_t OopEncodingHeapMax = NarrowOopHeapMax << LogMinObjAlignmentInBytes;
+
+char* Universe::preferred_heap_base(size_t heap_size, NARROW_OOP_MODE mode) {
+#ifdef _LP64
+  if (UseCompressedOops) {
+    assert(mode == UnscaledNarrowOop  ||
+           mode == ZeroBasedNarrowOop ||
+           mode == HeapBasedNarrowOop, "mode is invalid");
+
+    const size_t total_size = heap_size + HeapBaseMinAddress;
+    if (total_size <= OopEncodingHeapMax && (mode != HeapBasedNarrowOop)) {
+      if (total_size <= NarrowOopHeapMax && (mode == UnscaledNarrowOop) &&
+          (Universe::narrow_oop_shift() == 0)) {
+        // Use 32-bits oops without encoding and
+        // place heap's top on the 4Gb boundary
+        return (char*)(NarrowOopHeapMax - heap_size);
+      } else {
+        // Can't reserve with NarrowOopShift == 0
+        Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
+        if (mode == UnscaledNarrowOop ||
+            mode == ZeroBasedNarrowOop && total_size <= NarrowOopHeapMax) {
+          // Use zero based compressed oops with encoding and
+          // place heap's top on the 32Gb boundary in case
+          // total_size > 4Gb or failed to reserve below 4Gb.
+          return (char*)(OopEncodingHeapMax - heap_size);
+        }
+      }
+    } else {
+      // Can't reserve below 32Gb.
+      Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
+    }
+  }
+#endif
+  return NULL; // also return NULL (don't care) for 32-bit VM
+}
+
 jint Universe::initialize_heap() {
 
   if (UseParallelGC) {
@@ -773,6 +821,8 @@ jint Universe::initialize_heap() {
   if (status != JNI_OK) {
     return status;
   }
+
+#ifdef _LP64
   if (UseCompressedOops) {
     // Subtract a page because something can get allocated at heap base.
     // This also makes implicit null checking work, because the
@@ -780,8 +830,49 @@ jint Universe::initialize_heap() {
     // See needs_explicit_null_check.
     // Only set the heap base for compressed oops because it indicates
     // compressed oops for pstack code.
-    Universe::_heap_base = Universe::heap()->base() - os::vm_page_size();
+    if (PrintCompressedOopsMode) {
+      tty->cr();
+      tty->print("heap address: "PTR_FORMAT, Universe::heap()->base());
+    }
+    if ((uint64_t)Universe::heap()->reserved_region().end() > OopEncodingHeapMax) {
+      // Can't reserve heap below 32Gb.
+      Universe::set_narrow_oop_base(Universe::heap()->base() - os::vm_page_size());
+      Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
+      if (PrintCompressedOopsMode) {
+        tty->print(", Compressed Oops with base: "PTR_FORMAT, Universe::narrow_oop_base());
+      }
+    } else {
+      Universe::set_narrow_oop_base(0);
+      if (PrintCompressedOopsMode) {
+        tty->print(", zero based Compressed Oops");
+      }
+#ifdef _WIN64
+      if (!Universe::narrow_oop_use_implicit_null_checks()) {
+        // Don't need guard page for implicit checks in indexed addressing
+        // mode with zero based Compressed Oops.
+        Universe::set_narrow_oop_use_implicit_null_checks(true);
+      }
+#endif //  _WIN64
+      if((uint64_t)Universe::heap()->reserved_region().end() > NarrowOopHeapMax) {
+        // Can't reserve heap below 4Gb.
+        Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
+      } else {
+        assert(Universe::narrow_oop_shift() == 0, "use unscaled narrow oop");
+        if (PrintCompressedOopsMode) {
+          tty->print(", 32-bits Oops");
+        }
+      }
+    }
+    if (PrintCompressedOopsMode) {
+      tty->cr();
+      tty->cr();
+    }
   }
+  assert(Universe::narrow_oop_base() == (Universe::heap()->base() - os::vm_page_size()) ||
+         Universe::narrow_oop_base() == NULL, "invalid value");
+  assert(Universe::narrow_oop_shift() == LogMinObjAlignmentInBytes ||
+         Universe::narrow_oop_shift() == 0, "invalid value");
+#endif
 
   // We will never reach the CATCH below since Exceptions::_throw will cause
   // the VM to exit if an exception is thrown during initialization

src/share/vm/memory/universe.hpp

@@ -90,6 +90,19 @@ class LatestMethodOopCache : public CommonMethodOopCache {
   methodOop get_methodOop();
 };
 
+// For UseCompressedOops.
+struct NarrowOopStruct {
+  // Base address for oop-within-java-object materialization.
+  // NULL if using wide oops or zero based narrow oops.
+  address _base;
+  // Number of shift bits for encoding/decoding narrow oops.
+  // 0 if using wide oops or zero based unscaled narrow oops,
+  // LogMinObjAlignmentInBytes otherwise.
+  int     _shift;
+  // Generate code with implicit null checks for narrow oops.
+  bool    _use_implicit_null_checks;
+};
+
 
 class Universe: AllStatic {
   // Ugh.  Universe is much too friendly.
@@ -181,9 +194,9 @@ class Universe: AllStatic {
 
   // The particular choice of collected heap.
   static CollectedHeap* _collectedHeap;
-  // Base address for oop-within-java-object materialization.
-  // NULL if using wide oops.  Doubles as heap oop null value.
-  static address        _heap_base;
+
+  // For UseCompressedOops.
+  static struct NarrowOopStruct _narrow_oop;
 
   // array of dummy objects used with +FullGCAlot
   debug_only(static objArrayOop _fullgc_alot_dummy_array;)
@@ -328,8 +341,25 @@ class Universe: AllStatic {
   static CollectedHeap* heap() { return _collectedHeap; }
 
   // For UseCompressedOops
-  static address heap_base()       { return _heap_base; }
-  static address* heap_base_addr() { return &_heap_base; }
+  static address* narrow_oop_base_addr()              { return &_narrow_oop._base; }
+  static address  narrow_oop_base()                   { return  _narrow_oop._base; }
+  static int      narrow_oop_shift()                  { return  _narrow_oop._shift; }
+  static void     set_narrow_oop_base(address base)   { _narrow_oop._base  = base; }
+  static void     set_narrow_oop_shift(int shift)     { _narrow_oop._shift = shift; }
+  static bool     narrow_oop_use_implicit_null_checks()             { return  _narrow_oop._use_implicit_null_checks; }
+  static void     set_narrow_oop_use_implicit_null_checks(bool use) { _narrow_oop._use_implicit_null_checks = use; }
+  // Narrow Oop encoding mode:
+  // 0 - Use 32-bits oops without encoding when
+  //     NarrowOopHeapBaseMin + heap_size < 4Gb
+  // 1 - Use zero based compressed oops with encoding when
+  //     NarrowOopHeapBaseMin + heap_size < 32Gb
+  // 2 - Use compressed oops with heap base + encoding.
+  enum NARROW_OOP_MODE {
+    UnscaledNarrowOop  = 0,
+    ZeroBasedNarrowOop = 1,
+    HeapBasedNarrowOop = 2
+  };
+  static char* preferred_heap_base(size_t heap_size, NARROW_OOP_MODE mode);
 
   // Historic gc information
   static size_t get_heap_capacity_at_last_gc()         { return _heap_capacity_at_last_gc; }

src/share/vm/oops/oop.inline.hpp

@@ -148,10 +148,11 @@ inline bool oopDesc::is_null(narrowOop obj) { return obj == 0; }
 
 inline narrowOop oopDesc::encode_heap_oop_not_null(oop v) {
   assert(!is_null(v), "oop value can never be zero");
-  address heap_base = Universe::heap_base();
-  uint64_t pd = (uint64_t)(pointer_delta((void*)v, (void*)heap_base, 1));
+  address base = Universe::narrow_oop_base();
+  int    shift = Universe::narrow_oop_shift();
+  uint64_t  pd = (uint64_t)(pointer_delta((void*)v, (void*)base, 1));
   assert(OopEncodingHeapMax > pd, "change encoding max if new encoding");
-  uint64_t result = pd >> LogMinObjAlignmentInBytes;
+  uint64_t result = pd >> shift;
   assert((result & CONST64(0xffffffff00000000)) == 0, "narrow oop overflow");
   return (narrowOop)result;
 }
@@ -162,8 +163,9 @@ inline narrowOop oopDesc::encode_heap_oop(oop v) {
 
 inline oop oopDesc::decode_heap_oop_not_null(narrowOop v) {
   assert(!is_null(v), "narrow oop value can never be zero");
-  address heap_base = Universe::heap_base();
-  return (oop)(void*)((uintptr_t)heap_base + ((uintptr_t)v << LogMinObjAlignmentInBytes));
+  address base = Universe::narrow_oop_base();
+  int    shift = Universe::narrow_oop_shift();
+  return (oop)(void*)((uintptr_t)base + ((uintptr_t)v << shift));
 }
 
 inline oop oopDesc::decode_heap_oop(narrowOop v) {

src/share/vm/opto/addnode.cpp

@@ -756,7 +756,13 @@ const Type *AddPNode::mach_bottom_type( const MachNode* n) {
       if ( eti == NULL ) {
         // there must be one pointer among the operands
         guarantee(tptr == NULL, "must be only one pointer operand");
-        tptr = et->isa_oopptr();
+        if (UseCompressedOops && Universe::narrow_oop_shift() == 0) {
+          // 32-bits narrow oop can be the base of address expressions
+          tptr = et->make_ptr()->isa_oopptr();
+        } else {
+          // only regular oops are expected here
+          tptr = et->isa_oopptr();
+        }
         guarantee(tptr != NULL, "non-int operand must be pointer");
         if (tptr->higher_equal(tp->add_offset(tptr->offset())))
           tp = tptr; // Set more precise type for bailout

src/share/vm/opto/compile.cpp

@@ -2081,7 +2081,7 @@ static void final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &fpu ) {
 
 #ifdef _LP64
   case Op_CastPP:
-    if (n->in(1)->is_DecodeN() && UseImplicitNullCheckForNarrowOop) {
+    if (n->in(1)->is_DecodeN() && Universe::narrow_oop_use_implicit_null_checks()) {
       Compile* C = Compile::current();
       Node* in1 = n->in(1);
       const Type* t = n->bottom_type();
@@ -2136,7 +2136,7 @@ static void final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &fpu ) {
         new_in2 = in2->in(1);
       } else if (in2->Opcode() == Op_ConP) {
         const Type* t = in2->bottom_type();
-        if (t == TypePtr::NULL_PTR && UseImplicitNullCheckForNarrowOop) {
+        if (t == TypePtr::NULL_PTR && Universe::narrow_oop_use_implicit_null_checks()) {
           new_in2 = ConNode::make(C, TypeNarrowOop::NULL_PTR);
           //
           // This transformation together with CastPP transformation above

src/share/vm/opto/connode.cpp

@@ -433,7 +433,7 @@ Node *ConstraintCastNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
 // If not converting int->oop, throw away cast after constant propagation
 Node *CastPPNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
   const Type *t = ccp->type(in(1));
-  if (!t->isa_oop_ptr() || in(1)->is_DecodeN()) {
+  if (!t->isa_oop_ptr() || (in(1)->is_DecodeN() && Universe::narrow_oop_use_implicit_null_checks())) {
     return NULL; // do not transform raw pointers or narrow oops
   }
   return ConstraintCastNode::Ideal_DU_postCCP(ccp);

src/share/vm/opto/lcm.cpp

@@ -158,7 +158,14 @@ void Block::implicit_null_check(PhaseCFG *cfg, Node *proj, Node *val, int allowe
           continue;             // Give up if offset is beyond page size
         // cannot reason about it; is probably not implicit null exception
       } else {
-        const TypePtr* tptr = base->bottom_type()->is_ptr();
+        const TypePtr* tptr;
+        if (UseCompressedOops && Universe::narrow_oop_shift() == 0) {
+          // 32-bits narrow oop can be the base of address expressions
+          tptr = base->bottom_type()->make_ptr();
+        } else {
+          // only regular oops are expected here
+          tptr = base->bottom_type()->is_ptr();
+        }
         // Give up if offset is not a compile-time constant
         if( offset == Type::OffsetBot || tptr->_offset == Type::OffsetBot )
           continue;

src/share/vm/opto/matcher.cpp

@@ -1481,8 +1481,13 @@ MachNode *Matcher::ReduceInst( State *s, int rule, Node *&mem ) {
       const Type* mach_at = mach->adr_type();
       // DecodeN node consumed by an address may have different type
       // then its input. Don't compare types for such case.
-      if (m->adr_type() != mach_at && m->in(MemNode::Address)->is_AddP() &&
-          m->in(MemNode::Address)->in(AddPNode::Address)->is_DecodeN()) {
+      if (m->adr_type() != mach_at &&
+          (m->in(MemNode::Address)->is_DecodeN() ||
+           m->in(MemNode::Address)->is_AddP() &&
+           m->in(MemNode::Address)->in(AddPNode::Address)->is_DecodeN() ||
+           m->in(MemNode::Address)->is_AddP() &&
+           m->in(MemNode::Address)->in(AddPNode::Address)->is_AddP() &&
+           m->in(MemNode::Address)->in(AddPNode::Address)->in(AddPNode::Address)->is_DecodeN())) {
         mach_at = m->adr_type();
       }
       if (m->adr_type() != mach_at) {

src/share/vm/runtime/arguments.cpp

@@ -1211,7 +1211,9 @@ void Arguments::set_ergonomics_flags() {
     if (UseLargePages && UseCompressedOops) {
       // Cannot allocate guard pages for implicit checks in indexed addressing
       // mode, when large pages are specified on windows.
-      FLAG_SET_DEFAULT(UseImplicitNullCheckForNarrowOop, false);
+      // This flag could be switched ON if narrow oop base address is set to 0,
+      // see code in Universe::initialize_heap().
+      Universe::set_narrow_oop_use_implicit_null_checks(false);
     }
 #endif //  _WIN64
   } else {

src/share/vm/runtime/globals.hpp

@@ -303,11 +303,14 @@ class CommandLineFlags {
             "Use 32-bit object references in 64-bit VM. "                   \
             "lp64_product means flag is always constant in 32 bit VM")      \
                                                                             \
-  lp64_product(bool, CheckCompressedOops, trueInDebug,                      \
-            "generate checks in encoding/decoding code")                    \
+  notproduct(bool, CheckCompressedOops, true,                               \
+            "generate checks in encoding/decoding code in debug VM")        \
                                                                             \
-  product(bool, UseImplicitNullCheckForNarrowOop, true,                     \
-            "generate implicit null check in indexed addressing mode.")     \
+  product_pd(uintx, HeapBaseMinAddress,                                     \
+            "OS specific low limit for heap base address")                  \
+                                                                            \
+  diagnostic(bool, PrintCompressedOopsMode, false,                          \
+            "Print compressed oops base address and encoding mode")         \
                                                                             \
   /* UseMembar is theoretically a temp flag used for memory barrier         \
    * removal testing.  It was supposed to be removed before FCS but has     \

src/share/vm/runtime/os.hpp

@@ -243,7 +243,7 @@ class os: AllStatic {
 
   static char*  non_memory_address_word();
   // reserve, commit and pin the entire memory region
-  static char*  reserve_memory_special(size_t size);
+  static char*  reserve_memory_special(size_t size, char* addr = NULL);
   static bool   release_memory_special(char* addr, size_t bytes);
   static bool   large_page_init();
   static size_t large_page_size();

src/share/vm/runtime/virtualspace.cpp

@@ -109,6 +109,7 @@ ReservedSpace::ReservedSpace(const size_t prefix_size,
                              const size_t prefix_align,
                              const size_t suffix_size,
                              const size_t suffix_align,
+                             char* requested_address,
                              const size_t noaccess_prefix)
 {
   assert(prefix_size != 0, "sanity");
@@ -131,7 +132,7 @@ ReservedSpace::ReservedSpace(const size_t prefix_size,
   const bool try_reserve_special = UseLargePages &&
     prefix_align == os::large_page_size();
   if (!os::can_commit_large_page_memory() && try_reserve_special) {
-    initialize(size, prefix_align, true, NULL, noaccess_prefix);
+    initialize(size, prefix_align, true, requested_address, noaccess_prefix);
     return;
   }
 
@@ -146,7 +147,13 @@ ReservedSpace::ReservedSpace(const size_t prefix_size,
          noaccess_prefix == prefix_align, "noaccess prefix wrong");
 
   // Optimistically try to reserve the exact size needed.
-  char* addr = os::reserve_memory(size, NULL, prefix_align);
+  char* addr;
+  if (requested_address != 0) {
+    addr = os::attempt_reserve_memory_at(size,
+                                         requested_address-noaccess_prefix);
+  } else {
+    addr = os::reserve_memory(size, NULL, prefix_align);
+  }
   if (addr == NULL) return;
 
   // Check whether the result has the needed alignment (unlikely unless
@@ -206,12 +213,8 @@ void ReservedSpace::initialize(size_t size, size_t alignment, bool large,
   char* base = NULL;
 
   if (special) {
-    // It's not hard to implement reserve_memory_special() such that it can
-    // allocate at fixed address, but there seems no use of this feature
-    // for now, so it's not implemented.
-    assert(requested_address == NULL, "not implemented");
 
-    base = os::reserve_memory_special(size);
+    base = os::reserve_memory_special(size, requested_address);
 
     if (base != NULL) {
       // Check alignment constraints
@@ -372,7 +375,8 @@ ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment,
                                      bool large, char* requested_address) :
   ReservedSpace(size, alignment, large,
                 requested_address,
-                UseCompressedOops && UseImplicitNullCheckForNarrowOop ?
+                (UseCompressedOops && (Universe::narrow_oop_base() != NULL) &&
+                 Universe::narrow_oop_use_implicit_null_checks()) ?
                   lcm(os::vm_page_size(), alignment) : 0) {
   // Only reserved space for the java heap should have a noaccess_prefix
   // if using compressed oops.
@@ -382,9 +386,12 @@ ReservedHeapSpace::ReservedHeapSpace(size_t size, size_t alignment,
 ReservedHeapSpace::ReservedHeapSpace(const size_t prefix_size,
                                      const size_t prefix_align,
                                      const size_t suffix_size,
-                                     const size_t suffix_align) :
+                                     const size_t suffix_align,
+                                     char* requested_address) :
   ReservedSpace(prefix_size, prefix_align, suffix_size, suffix_align,
-                UseCompressedOops && UseImplicitNullCheckForNarrowOop ?
+                requested_address,
+                (UseCompressedOops && (Universe::narrow_oop_base() != NULL) &&
+                 Universe::narrow_oop_use_implicit_null_checks()) ?
                   lcm(os::vm_page_size(), prefix_align) : 0) {
   protect_noaccess_prefix(prefix_size+suffix_size);
 }

src/share/vm/runtime/virtualspace.hpp

@@ -73,7 +73,8 @@ class ReservedSpace VALUE_OBJ_CLASS_SPEC {
                 const size_t noaccess_prefix = 0);
   ReservedSpace(const size_t prefix_size, const size_t prefix_align,
                 const size_t suffix_size, const size_t suffix_align,
-                const size_t noaccess_prefix);
+                char* requested_address,
+                const size_t noaccess_prefix = 0);
 
   // Accessors
   char*  base()      const { return _base;      }
@@ -121,7 +122,8 @@ public:
   ReservedHeapSpace(size_t size, size_t forced_base_alignment,
                     bool large, char* requested_address);
   ReservedHeapSpace(const size_t prefix_size, const size_t prefix_align,
-                    const size_t suffix_size, const size_t suffix_align);
+                    const size_t suffix_size, const size_t suffix_align,
+                    char* requested_address);
 };
 
 // VirtualSpace is data structure for committing a previously reserved address range in smaller chunks.

src/share/vm/runtime/vmStructs.cpp

@@ -263,7 +263,9 @@ static inline uint64_t cast_uint64_t(size_t x)
      static_field(Universe,                    _bootstrapping,                                bool)                                  \
      static_field(Universe,                    _fully_initialized,                            bool)                                  \
      static_field(Universe,                    _verify_count,                                 int)                                   \
-     static_field(Universe,                    _heap_base,                                    address)                                   \
+     static_field(Universe,                    _narrow_oop._base,                             address)                               \
+     static_field(Universe,                    _narrow_oop._shift,                            int)                                   \
+     static_field(Universe,                    _narrow_oop._use_implicit_null_checks,         bool)                                  \
                                                                                                                                      \
   /**********************************************************************************/                                               \
   /* Generation and Space hierarchies                                               */                                               \