4965777: GC changes to support use of discovered field for pending references
Summary: If and when the reference handler thread is able to use the discovered field to link reference objects in its pending list, so will GC. In that case, GC will scan through this field once a reference object has been placed on the pending list, but not scan that field before that stage, as the field is used by the concurrent GC thread to link discovered objects. When ReferenceHandleR thread does not use the discovered field for the purpose of linking the elements in the pending list, as would be the case in older JDKs, the JVM will fall back to the old behaviour of using the next field for that purpose.
Reviewed-by: jcoomes, mchung, stefank
#
# Copyright (c) 2001, 2011, 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. Oracle designates this
# particular file as subject to the "Classpath" exception as provided
# by Oracle in the LICENSE file that accompanied this code.
#
# 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.
#
################################################################
# HOTSPOT TARGETS
################################################################
# All the output from a hotspot build should be re-located to the
# build output area.
#
HOTSPOT_OUTPUTDIR = $(HOTSPOT_DIR)/outputdir
# HOTSPOT_EXPORT_PATH points to a dir that contains files
# that are needed in an SDK build, in the same relative positions as
# these files are in an SDK image.
# The SDK java/redist/Makefile will copy files from HOTSPOT_EXPORT_PATH
# into the SDK being built.
# This is the export path supplied to the hotspot makefiles.
#
HOTSPOT_EXPORT_PATH = $(HOTSPOT_DIR)/import
# Default targets
HOTSPOT = hotspot-sanity hotspot-build
hotspot:: $(HOTSPOT)
# Hotspot clobber removes the output directory and exported files
hotspot-clobber::
$(RM) -r $(HOTSPOT_OUTPUTDIR)
$(RM) -r $(HOTSPOT_EXPORT_PATH)
hotspot-sanity::
@$(MKDIR) -p $(HOTSPOT_OUTPUTDIR)
@$(MKDIR) -p $(HOTSPOT_EXPORT_PATH)
@$(ECHO) "Hotspot Settings: \n" \
" HOTSPOT_BUILD_JOBS = $(HOTSPOT_BUILD_JOBS) \n" \
" HOTSPOT_OUTPUTDIR = $(HOTSPOT_OUTPUTDIR) \n" \
" HOTSPOT_EXPORT_PATH = $(HOTSPOT_EXPORT_PATH) \n" \
"\n" >> $(MESSAGE_FILE)
#
# Basic hotspot build and export of it's files
#
HOTSPOT_TARGET = all_product
ifeq ($(DEBUG_NAME), debug)
HOTSPOT_TARGET = all_debug
endif
ifeq ($(DEBUG_NAME), fastdebug)
HOTSPOT_TARGET = all_fastdebug
endif
ifeq ($(ZERO_BUILD), true)
ifeq ($(SHARK_BUILD), true)
HOTSPOT_TARGET := $(HOTSPOT_TARGET)shark
else
HOTSPOT_TARGET := $(HOTSPOT_TARGET)zero
endif
endif
HOTSPOT_BUILD_ARGUMENTS += $(COMMON_BUILD_ARGUMENTS)
HOTSPOT_BUILD_ARGUMENTS += ALT_OUTPUTDIR=$(HOTSPOT_OUTPUTDIR)
HOTSPOT_BUILD_ARGUMENTS += ALT_EXPORT_PATH=$(HOTSPOT_EXPORT_PATH)
# Why do these need to be passed in? Because of windows nmake? and MAKEFLAGS=?
# Or is there something wrong with hotspot/make/Makefile?
HOTSPOT_BUILD_ARGUMENTS += ALT_SLASH_JAVA=$(SLASH_JAVA)
HOTSPOT_BUILD_ARGUMENTS += ALT_BOOTDIR=$(BOOTDIR)
ifeq ($(BUILD_LANGTOOLS), true)
HOTSPOT_BUILD_ARGUMENTS += ALT_LANGTOOLS_DIST=$(ABS_LANGTOOLS_DIST)
endif
hotspot-build::
$(MKDIR) -p $(HOTSPOT_OUTPUTDIR)
$(MKDIR) -p $(HOTSPOT_EXPORT_PATH)
@$(call MakeStart,hotspot,$(HOTSPOT_TARGET))
$(CD) $(HOTSPOT_TOPDIR)/make && \
$(MAKE) $(HOTSPOT_BUILD_ARGUMENTS) $(HOTSPOT_TARGET)
@$(call MakeFinish,hotspot,$(HOTSPOT_TARGET))
#####################
# .PHONY
#####################
.PHONY: hotspot-build hotspot-clobber hotspot-sanity