6378256: Performance problem with System.identityHashCode in client compiler

Enabled C1 optimization to try pull out hashCode from object header, before calling into the VM.

Reviewed-by: dlong, roland, thartmann

hotspot/src/cpu/x86/vm/sharedRuntime_x86.cpp

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2016, Oracle and/or its affiliates. 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "asm/macroAssembler.hpp"
+#include "runtime/sharedRuntime.hpp"
+#include "vmreg_x86.inline.hpp"
+#ifdef COMPILER1
+#include "c1/c1_Runtime1.hpp"
+#endif //COMPILER1
+
+#define __ masm->
+
+#ifdef COMPILER1
+// ---------------------------------------------------------------------------
+// Object.hashCode, System.identityHashCode can pull the hashCode from the
+// header word instead of doing a full VM transition once it's been computed.
+// Since hashCode is usually polymorphic at call sites we can't do this
+// optimization at the call site without a lot of work.
+void SharedRuntime::inline_check_hashcode_from_object_header(MacroAssembler* masm,
+                                 methodHandle method,
+                                 Register obj_reg,
+                                 Register result) {
+  Label slowCase;
+
+  // Unlike for Object.hashCode, System.identityHashCode is static method and
+  // gets object as argument instead of the receiver.
+  if (method->intrinsic_id() == vmIntrinsics::_identityHashCode) {
+    Label Continue;
+    // return 0 for null reference input
+    __ cmpptr(obj_reg, (int32_t)NULL_WORD);
+    __ jcc(Assembler::notEqual, Continue);
+    __ xorptr(result, result);
+    __ ret(0);
+    __ bind(Continue);
+  }
+
+  __ movptr(result, Address(obj_reg, oopDesc::mark_offset_in_bytes()));
+
+  // check if locked
+  __ testptr(result, markOopDesc::unlocked_value);
+  __ jcc(Assembler::zero, slowCase);
+
+  if (UseBiasedLocking) {
+    // Check if biased and fall through to runtime if so
+    __ testptr(result, markOopDesc::biased_lock_bit_in_place);
+    __ jcc(Assembler::notZero, slowCase);
+  }
+
+  // get hash
+#ifdef _LP64
+  // Read the header and build a mask to get its hash field.
+  // Depend on hash_mask being at most 32 bits and avoid the use of hash_mask_in_place
+  // because it could be larger than 32 bits in a 64-bit vm. See markOop.hpp.
+  __ shrptr(result, markOopDesc::hash_shift);
+  __ andptr(result, markOopDesc::hash_mask);
+#else
+  __ andptr(result, markOopDesc::hash_mask_in_place);
+#endif //_LP64
+
+  // test if hashCode exists
+  __ jcc(Assembler::zero, slowCase);
+#ifndef _LP64
+  __ shrptr(result, markOopDesc::hash_shift);
+#endif
+  __ ret(0);
+  __ bind(slowCase);
+}
+#endif //COMPILER1
+