--- old/make/autoconf/hotspot.m4	2018-12-03 17:48:00.628170373 +0100
+++ new/make/autoconf/hotspot.m4	2018-12-03 17:48:00.473171479 +0100
@@ -25,7 +25,7 @@
 
 # All valid JVM features, regardless of platform
 VALID_JVM_FEATURES="compiler1 compiler2 zero minimal dtrace jvmti jvmci \
-    graal vm-structs jni-check services management cmsgc epsilongc g1gc parallelgc serialgc zgc nmt cds \
+    graal vm-structs jni-check services management cmsgc epsilongc g1gc parallelgc serialgc shenandoahgc zgc nmt cds \
     static-build link-time-opt aot jfr"
 
 # Deprecated JVM features (these are ignored, but with a warning)
@@ -325,6 +325,15 @@
     fi
   fi
 
+  # Only enable Shenandoah on supported arches
+  AC_MSG_CHECKING([if shenandoah can be built])
+  if test "x$OPENJDK_TARGET_CPU_ARCH" = "xx86" || test "x$OPENJDK_TARGET_CPU" = "xaarch64" ; then
+    AC_MSG_RESULT([yes])
+  else
+    DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES shenandoahgc"
+    AC_MSG_RESULT([no, platform not supported])
+  fi
+
   # Only enable ZGC on supported platforms
   AC_MSG_CHECKING([if zgc can be built])
   if test "x$OPENJDK_TARGET_OS" = "xlinux" && test "x$OPENJDK_TARGET_CPU" = "xx86_64"; then
@@ -336,7 +345,7 @@
 
   # Disable unsupported GCs for Zero
   if HOTSPOT_CHECK_JVM_VARIANT(zero); then
-    DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES epsilongc g1gc zgc"
+    DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES epsilongc g1gc zgc shenandoahgc"
   fi
 
   # Turn on additional features based on other parts of configure
@@ -470,7 +479,7 @@
   fi
 
   # All variants but minimal (and custom) get these features
-  NON_MINIMAL_FEATURES="$NON_MINIMAL_FEATURES cmsgc g1gc parallelgc serialgc epsilongc jni-check jvmti management nmt services vm-structs zgc"
+  NON_MINIMAL_FEATURES="$NON_MINIMAL_FEATURES cmsgc g1gc parallelgc serialgc epsilongc shenandoahgc jni-check jvmti management nmt services vm-structs zgc"
 
   # Disable CDS on AIX.
   if test "x$OPENJDK_TARGET_OS" = "xaix"; then
--- old/make/hotspot/gensrc/GensrcAdlc.gmk	2018-12-03 17:48:00.856168745 +0100
+++ new/make/hotspot/gensrc/GensrcAdlc.gmk	2018-12-03 17:48:00.697169880 +0100
@@ -136,6 +136,12 @@
       $d/os_cpu/$(HOTSPOT_TARGET_OS)_$(HOTSPOT_TARGET_CPU_ARCH)/$(HOTSPOT_TARGET_OS)_$(HOTSPOT_TARGET_CPU_ARCH).ad \
     )))
 
+  ifeq ($(call check-jvm-feature, shenandoahgc), true)
+    AD_SRC_FILES += $(call uniq, $(wildcard $(foreach d, $(AD_SRC_ROOTS), \
+        $d/cpu/$(HOTSPOT_TARGET_CPU_ARCH)/gc/shenandoah/shenandoah_$(HOTSPOT_TARGET_CPU).ad \
+      )))
+  endif
+
   SINGLE_AD_SRCFILE := $(ADLC_SUPPORT_DIR)/all-ad-src.ad
 
   INSERT_FILENAME_AWK_SCRIPT := \
--- old/make/hotspot/lib/JvmFeatures.gmk	2018-12-03 17:48:01.077167167 +0100
+++ new/make/hotspot/lib/JvmFeatures.gmk	2018-12-03 17:48:00.921168281 +0100
@@ -166,6 +166,13 @@
   JVM_EXCLUDE_PATTERNS += gc/z
 endif
 
+ifneq ($(call check-jvm-feature, shenandoahgc), true)
+  JVM_CFLAGS_FEATURES += -DINCLUDE_SHENANDOAHGC=0
+  JVM_EXCLUDE_PATTERNS += gc/shenandoah
+else
+  JVM_CFLAGS_FEATURES += -DSUPPORT_BARRIER_ON_PRIMITIVES -DSUPPORT_NOT_TO_SPACE_INVARIANT
+endif
+
 ifneq ($(call check-jvm-feature, jfr), true)
   JVM_CFLAGS_FEATURES += -DINCLUDE_JFR=0
   JVM_EXCLUDE_PATTERNS += jfr
--- old/make/hotspot/lib/JvmOverrideFiles.gmk	2018-12-03 17:48:01.303165553 +0100
+++ new/make/hotspot/lib/JvmOverrideFiles.gmk	2018-12-03 17:48:01.144166688 +0100
@@ -36,6 +36,11 @@
   BUILD_LIBJVM_assembler_x86.cpp_CXXFLAGS := -Wno-maybe-uninitialized
   BUILD_LIBJVM_cardTableBarrierSetAssembler_x86.cpp_CXXFLAGS := -Wno-maybe-uninitialized
   BUILD_LIBJVM_interp_masm_x86.cpp_CXXFLAGS := -Wno-uninitialized
+  ifeq ($(DEBUG_LEVEL), release)
+    # Need extra inlining to collapse all marking code into the hot marking loop
+    BUILD_LIBJVM_shenandoahConcurrentMark.cpp_CXXFLAGS := --param inline-unit-growth=1000
+    BUILD_LIBJVM_shenandoahTraversalGC.cpp_CXXFLAGS := --param inline-unit-growth=1000
+  endif
 endif
 
 LIBJVM_FDLIBM_COPY_OPT_FLAG := $(CXX_O_FLAG_NONE)