diff -r d58442b8abc1 -r 650335128b9d src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.api.directives.test/src/org/graalvm/compiler/api/directives/test/ProbabilityDirectiveTest.java
--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.api.directives.test/src/org/graalvm/compiler/api/directives/test/ProbabilityDirectiveTest.java	Thu Jun 27 03:33:44 2019 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.api.directives.test/src/org/graalvm/compiler/api/directives/test/ProbabilityDirectiveTest.java	Tue Jul 23 11:36:05 2019 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2019, 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
diff -r d58442b8abc1 -r 650335128b9d src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/GraalHotSpotVMConfig.java
--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/GraalHotSpotVMConfig.java	Thu Jun 27 03:33:44 2019 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/GraalHotSpotVMConfig.java	Tue Jul 23 11:36:05 2019 -0700
@@ -344,6 +344,7 @@
     public final int threadIsMethodHandleReturnOffset = getFieldOffset("JavaThread::_is_method_handle_return", Integer.class, "int");
     public final int threadObjectResultOffset = getFieldOffset("JavaThread::_vm_result", Integer.class, "oop");
     public final int jvmciCountersThreadOffset = getFieldOffset("JavaThread::_jvmci_counters", Integer.class, "jlong*");
+    public final int doingUnsafeAccessOffset = getFieldOffset("JavaThread::_doing_unsafe_access", Integer.class, "bool", Integer.MAX_VALUE);
     public final int javaThreadReservedStackActivationOffset = versioned.javaThreadReservedStackActivationOffset;
 
     public boolean requiresReservedStackCheck(List<ResolvedJavaMethod> methods) {
diff -r d58442b8abc1 -r 650335128b9d src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/meta/HotSpotGraphBuilderPlugins.java
--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/meta/HotSpotGraphBuilderPlugins.java	Thu Jun 27 03:33:44 2019 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/meta/HotSpotGraphBuilderPlugins.java	Tue Jul 23 11:36:05 2019 -0700
@@ -175,7 +175,7 @@
                 registerGHASHPlugins(invocationPlugins, config, metaAccess, foreignCalls);
                 registerCounterModePlugins(invocationPlugins, config, replacementBytecodeProvider);
                 registerBase64Plugins(invocationPlugins, config, metaAccess, foreignCalls);
-                registerUnsafePlugins(invocationPlugins, replacementBytecodeProvider);
+                registerUnsafePlugins(invocationPlugins, config, replacementBytecodeProvider);
                 StandardGraphBuilderPlugins.registerInvocationPlugins(metaAccess, snippetReflection, invocationPlugins, replacementBytecodeProvider, true, false);
                 registerArrayPlugins(invocationPlugins, replacementBytecodeProvider);
                 registerStringPlugins(invocationPlugins, replacementBytecodeProvider);
@@ -276,15 +276,16 @@
         r.registerMethodSubstitution(ReflectionSubstitutions.class, "getClassAccessFlags", Class.class);
     }
 
-    private static void registerUnsafePlugins(InvocationPlugins plugins, BytecodeProvider replacementBytecodeProvider) {
+    private static void registerUnsafePlugins(InvocationPlugins plugins, GraalHotSpotVMConfig config, BytecodeProvider replacementBytecodeProvider) {
         Registration r;
         if (JavaVersionUtil.JAVA_SPEC <= 8) {
             r = new Registration(plugins, Unsafe.class, replacementBytecodeProvider);
         } else {
             r = new Registration(plugins, "jdk.internal.misc.Unsafe", replacementBytecodeProvider);
         }
-        r.registerMethodSubstitution(HotSpotUnsafeSubstitutions.class, HotSpotUnsafeSubstitutions.copyMemoryName, "copyMemory", Receiver.class, Object.class, long.class, Object.class, long.class,
-                        long.class);
+        String substituteMethodName = config.doingUnsafeAccessOffset != Integer.MAX_VALUE ? "copyMemoryGuarded" : "copyMemory";
+        r.registerMethodSubstitution(HotSpotUnsafeSubstitutions.class, HotSpotUnsafeSubstitutions.copyMemoryName, substituteMethodName, Receiver.class, Object.class, long.class, Object.class,
+                        long.class, long.class);
     }
 
     private static final LocationIdentity INSTANCE_KLASS_CONSTANTS = NamedLocationIdentity.immutable("InstanceKlass::_constants");
diff -r d58442b8abc1 -r 650335128b9d src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/meta/HotSpotUnsafeSubstitutions.java
--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/meta/HotSpotUnsafeSubstitutions.java	Thu Jun 27 03:33:44 2019 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/meta/HotSpotUnsafeSubstitutions.java	Tue Jul 23 11:36:05 2019 -0700
@@ -24,12 +24,17 @@
 
 package org.graalvm.compiler.hotspot.meta;
 
+import static org.graalvm.compiler.hotspot.GraalHotSpotVMConfig.INJECTED_VMCONFIG;
+import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.doingUnsafeAccessOffset;
+
 import org.graalvm.compiler.api.replacements.ClassSubstitution;
 import org.graalvm.compiler.api.replacements.MethodSubstitution;
 import org.graalvm.compiler.hotspot.HotSpotBackend;
+import org.graalvm.compiler.hotspot.nodes.CurrentJavaThreadNode;
 import org.graalvm.compiler.nodes.ComputeObjectAddressNode;
 import org.graalvm.compiler.serviceprovider.JavaVersionUtil;
 import org.graalvm.compiler.word.Word;
+import jdk.internal.vm.compiler.word.LocationIdentity;
 import jdk.internal.vm.compiler.word.WordFactory;
 
 @ClassSubstitution(className = {"jdk.internal.misc.Unsafe", "sun.misc.Unsafe"})
@@ -43,6 +48,24 @@
         Word srcAddr = WordFactory.unsigned(ComputeObjectAddressNode.get(srcBase, srcOffset));
         Word dstAddr = WordFactory.unsigned(ComputeObjectAddressNode.get(destBase, destOffset));
         Word size = WordFactory.signed(bytes);
+
         HotSpotBackend.unsafeArraycopy(srcAddr, dstAddr, size);
     }
+
+    @SuppressWarnings("unused")
+    @MethodSubstitution(value = "copyMemory", isStatic = false)
+    static void copyMemoryGuarded(Object receiver, Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes) {
+        Word srcAddr = WordFactory.unsigned(ComputeObjectAddressNode.get(srcBase, srcOffset));
+        Word dstAddr = WordFactory.unsigned(ComputeObjectAddressNode.get(destBase, destOffset));
+        Word size = WordFactory.signed(bytes);
+        Word javaThread = CurrentJavaThreadNode.get();
+        int offset = doingUnsafeAccessOffset(INJECTED_VMCONFIG);
+        LocationIdentity any = LocationIdentity.any();
+
+        /* Set doingUnsafeAccess to guard and handle unsafe memory access failures */
+        javaThread.writeByte(offset, (byte) 1, any);
+        HotSpotBackend.unsafeArraycopy(srcAddr, dstAddr, size);
+        /* Reset doingUnsafeAccess */
+        javaThread.writeByte(offset, (byte) 0, any);
+    }
 }
diff -r d58442b8abc1 -r 650335128b9d src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/replacements/HotSpotReplacementsUtil.java
--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/replacements/HotSpotReplacementsUtil.java	Thu Jun 27 03:33:44 2019 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/replacements/HotSpotReplacementsUtil.java	Tue Jul 23 11:36:05 2019 -0700
@@ -187,6 +187,14 @@
         return config.verifyOops;
     }
 
+    /**
+     * @see GraalHotSpotVMConfig#doingUnsafeAccessOffset
+     */
+    @Fold
+    public static int doingUnsafeAccessOffset(@InjectedParameter GraalHotSpotVMConfig config) {
+        return config.doingUnsafeAccessOffset;
+    }
+
     public static final LocationIdentity EXCEPTION_OOP_LOCATION = NamedLocationIdentity.mutable("ExceptionOop");
 
     /**
diff -r d58442b8abc1 -r 650335128b9d src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir.amd64/src/org/graalvm/compiler/lir/amd64/AMD64StringLatin1InflateOp.java
--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir.amd64/src/org/graalvm/compiler/lir/amd64/AMD64StringLatin1InflateOp.java	Thu Jun 27 03:33:44 2019 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir.amd64/src/org/graalvm/compiler/lir/amd64/AMD64StringLatin1InflateOp.java	Tue Jul 23 11:36:05 2019 -0700
@@ -29,11 +29,9 @@
 import static jdk.vm.ci.amd64.AMD64.rdi;
 import static jdk.vm.ci.amd64.AMD64.rdx;
 import static jdk.vm.ci.amd64.AMD64.rsi;
-
 import static jdk.vm.ci.code.ValueUtil.asRegister;
 import static org.graalvm.compiler.lir.LIRInstruction.OperandFlag.REG;
 
-import jdk.vm.ci.amd64.AMD64;
 import org.graalvm.compiler.asm.Label;
 import org.graalvm.compiler.asm.amd64.AMD64Address;
 import org.graalvm.compiler.asm.amd64.AMD64Assembler;
@@ -44,6 +42,7 @@
 import org.graalvm.compiler.lir.asm.CompilationResultBuilder;
 import org.graalvm.compiler.lir.gen.LIRGeneratorTool;
 
+import jdk.vm.ci.amd64.AMD64;
 import jdk.vm.ci.amd64.AMD64Kind;
 import jdk.vm.ci.code.Register;
 import jdk.vm.ci.meta.Value;
@@ -52,9 +51,13 @@
 public final class AMD64StringLatin1InflateOp extends AMD64LIRInstruction {
     public static final LIRInstructionClass<AMD64StringLatin1InflateOp> TYPE = LIRInstructionClass.create(AMD64StringLatin1InflateOp.class);
 
-    @Alive({REG}) private Value rsrc;
-    @Alive({REG}) private Value rdst;
-    @Alive({REG}) private Value rlen;
+    @Use({REG}) private Value rsrc;
+    @Use({REG}) private Value rdst;
+    @Use({REG}) private Value rlen;
+
+    @Temp({REG}) private Value rsrcTemp;
+    @Temp({REG}) private Value rdstTemp;
+    @Temp({REG}) private Value rlenTemp;
 
     @Temp({REG}) private Value vtmp1;
     @Temp({REG}) private Value rtmp2;
@@ -66,9 +69,9 @@
         assert asRegister(dst).equals(rdi);
         assert asRegister(len).equals(rdx);
 
-        rsrc = src;
-        rdst = dst;
-        rlen = len;
+        rsrcTemp = rsrc = src;
+        rdstTemp = rdst = dst;
+        rlenTemp = rlen = len;
 
         vtmp1 = tool.newVariable(LIRKind.value(AMD64Kind.V512_BYTE));
         rtmp2 = tool.newVariable(LIRKind.value(AMD64Kind.DWORD));
diff -r d58442b8abc1 -r 650335128b9d src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir.amd64/src/org/graalvm/compiler/lir/amd64/AMD64StringUTF16CompressOp.java
--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir.amd64/src/org/graalvm/compiler/lir/amd64/AMD64StringUTF16CompressOp.java	Thu Jun 27 03:33:44 2019 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir.amd64/src/org/graalvm/compiler/lir/amd64/AMD64StringUTF16CompressOp.java	Tue Jul 23 11:36:05 2019 -0700
@@ -31,12 +31,10 @@
 import static jdk.vm.ci.amd64.AMD64.rdi;
 import static jdk.vm.ci.amd64.AMD64.rdx;
 import static jdk.vm.ci.amd64.AMD64.rsi;
-
 import static jdk.vm.ci.amd64.AMD64.rsp;
 import static jdk.vm.ci.code.ValueUtil.asRegister;
 import static org.graalvm.compiler.lir.LIRInstruction.OperandFlag.REG;
 
-import jdk.vm.ci.amd64.AMD64;
 import org.graalvm.compiler.asm.Label;
 import org.graalvm.compiler.asm.amd64.AMD64Address;
 import org.graalvm.compiler.asm.amd64.AMD64Assembler;
@@ -47,6 +45,7 @@
 import org.graalvm.compiler.lir.asm.CompilationResultBuilder;
 import org.graalvm.compiler.lir.gen.LIRGeneratorTool;
 
+import jdk.vm.ci.amd64.AMD64;
 import jdk.vm.ci.amd64.AMD64Kind;
 import jdk.vm.ci.code.Register;
 import jdk.vm.ci.meta.Value;
@@ -56,9 +55,13 @@
     public static final LIRInstructionClass<AMD64StringUTF16CompressOp> TYPE = LIRInstructionClass.create(AMD64StringUTF16CompressOp.class);
 
     @Def({REG}) private Value rres;
-    @Alive({REG}) private Value rsrc;
-    @Alive({REG}) private Value rdst;
-    @Alive({REG}) private Value rlen;
+    @Use({REG}) private Value rsrc;
+    @Use({REG}) private Value rdst;
+    @Use({REG}) private Value rlen;
+
+    @Temp({REG}) private Value rsrcTemp;
+    @Temp({REG}) private Value rdstTemp;
+    @Temp({REG}) private Value rlenTemp;
 
     @Temp({REG}) private Value vtmp1;
     @Temp({REG}) private Value vtmp2;
@@ -75,9 +78,9 @@
         assert asRegister(res).equals(rax);
 
         rres = res;
-        rsrc = src;
-        rdst = dst;
-        rlen = len;
+        rsrcTemp = rsrc = src;
+        rdstTemp = rdst = dst;
+        rlenTemp = rlen = len;
 
         LIRKind vkind = LIRKind.value(AMD64Kind.V512_BYTE);