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package com.oracle.truffle.api.profiles;
import java.util.Objects;
import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
/**
*
* Specialized value profile to capture certain properties of Object runtime values.
* Value profiles require a runtime check in their initialized state to verify their profiled
* assumption. Value profiles are limited to capture monomorphic profiles only. This means that if
* two or more identities or classes are profiles within a single profile then the profile has no
* effect and no overhead after compilation. There are specialized versions of this profile with
* less interpreter footprint for {@link ConditionProfile boolean}, {@link ByteValueProfile byte},
* {@link IntValueProfile int}, {@link LongValueProfile long}, {@link FloatValueProfile float} and
* {@link DoubleValueProfile double} values.
*
*
*
* Usage example:
*
*
* class SampleNode extends Node {
*
* final ValueProfile profile = ValueProfile.create{Identity,Class}Profile();
*
* Object execute(Object input) {
* Object profiledValue = profile.profile(input);
* // compiler may know now more about profiledValue
* return profieldValue;
* }
* }
*
*
*
*
* {@inheritDoc}
*
* @see #createIdentityProfile()
* @see #createClassProfile()
* @since 0.10
*/
public abstract class ValueProfile extends Profile {
ValueProfile() {
}
/** @since 0.10 */
public abstract T profile(T value);
/**
*
* Returns a value profile that profiles the exact class of a value. It will check the class of
* the profiled value and provide additional information to the compiler if only non-null values
* of exactly one concrete Java class are passed as a parameter to the
* {@link ValueProfile#profile} method. This can be beneficial if subsequent code can take
* advantage of knowing the concrete class of the value. The profile will degrade to the generic
* case if a null value or if at least two instances of two different Java classes are
* registered.
*
*
*
* Compilation notes: Value profiles require a runtime check in their initialized state
* to verify their profiled class. If two classes have been seen on a single profile instance
* then this profile will transition to a generic state with no overhead.
*
*
* @see ValueProfile usage example
* @since 0.10
*/
public static ValueProfile createClassProfile() {
if (Profile.isProfilingEnabled()) {
return ExactClass.create();
} else {
return Disabled.INSTANCE;
}
}
/**
*
* Returns a value profile that profiles the object identity of a value. A single instance can
* only profile one particular instance.
*
*
*
* Compilation notes: Identity profiles require a runtime check to verify their profiled
* object identity. If two identities have been seen on a single profile instance then this
* profile will transition to a generic state with no overhead.
*
*
* @since 0.10
*/
public static ValueProfile createIdentityProfile() {
if (Profile.isProfilingEnabled()) {
return Identity.create();
} else {
return Disabled.INSTANCE;
}
}
/**
*
* Returns a value profile that profiles the object equality of a value. A single instance can
* only profile one set of equal values.
*
*
*
* Compilation notes: Equality profiles inline the body of the equal method of the first
* profiled value in order to verify its assumption. Please take care that you do this only for
* equals implementations that your guest language actually has control over otherwise your
* compiled code might contain recursions or too much code. If two non equal objects have been
* seen on a single profile instance then this profile will transition to a generic state with
* no overhead.
*
*
* @since 0.10
*/
public static ValueProfile createEqualityProfile() {
if (Profile.isProfilingEnabled()) {
return Equality.create();
} else {
return Disabled.INSTANCE;
}
}
/**
* Returns the uncached version of the profile. The uncached version of a profile does nothing.
*
* @since 19.0
*/
public static ValueProfile getUncached() {
return Disabled.INSTANCE;
}
static final class Disabled extends ValueProfile {
static final ValueProfile INSTANCE = new Disabled();
@Override
protected Object clone() {
return INSTANCE;
}
@Override
public T profile(T value) {
return value;
}
@Override
public String toString() {
return toStringDisabled(ValueProfile.class);
}
}
static final class Equality extends ValueProfile {
private static final Object GENERIC = new Object();
@CompilationFinal protected Object cachedValue = null;
Equality() {
}
@Override
@SuppressWarnings("unchecked")
public T profile(T newValue) {
// Field needs to be cached in local variable for thread safety and startup speed.
Object cached = this.cachedValue;
if (cached != GENERIC) {
if (cached != null && cached.equals(newValue)) {
return (T) cached;
} else {
CompilerDirectives.transferToInterpreterAndInvalidate();
if (cached == null && newValue != null) {
cachedValue = newValue;
} else {
cachedValue = GENERIC;
}
}
}
return newValue;
}
public boolean isGeneric() {
return getCachedValue() == GENERIC;
}
public boolean isUninitialized() {
return getCachedValue() == null;
}
public Object getCachedValue() {
return cachedValue;
}
@Override
public String toString() {
return toString(ValueProfile.class, isUninitialized(), isGeneric(),
String.format("value == %s@%x", cachedValue != null ? cachedValue.getClass().getSimpleName() : "null", Objects.hash(cachedValue)));
}
/* Needed for lazy class loading. */
static ValueProfile create() {
return new Equality();
}
}
static final class Identity extends ValueProfile {
private static final Object UNINITIALIZED = new Object();
private static final Object GENERIC = new Object();
@CompilationFinal protected Object cachedValue = UNINITIALIZED;
Identity() {
}
@Override
@SuppressWarnings("unchecked")
public T profile(T newValue) {
// Field needs to be cached in local variable for thread safety and startup speed.
Object cached = this.cachedValue;
if (cached != GENERIC) {
if (cached == newValue) {
return (T) cached;
} else {
CompilerDirectives.transferToInterpreterAndInvalidate();
if (cachedValue == UNINITIALIZED) {
cachedValue = newValue;
} else {
cachedValue = GENERIC;
}
}
}
return newValue;
}
public boolean isGeneric() {
return getCachedValue() == GENERIC;
}
public boolean isUninitialized() {
return getCachedValue() == UNINITIALIZED;
}
public Object getCachedValue() {
return cachedValue;
}
@Override
public String toString() {
return toString(ValueProfile.class, isUninitialized(), isGeneric(),
String.format("value == %s@%x", cachedValue != null ? cachedValue.getClass().getSimpleName() : "null", Objects.hash(cachedValue)));
}
/* Needed for lazy class loading. */
static ValueProfile create() {
return new Identity();
}
}
static final class ExactClass extends ValueProfile {
@CompilationFinal protected Class cachedClass;
ExactClass() {
}
public static ValueProfile create() {
return new ExactClass();
}
@SuppressWarnings("unchecked")
@Override
public T profile(T value) {
// Field needs to be cached in local variable for thread safety and startup speed.
Class clazz = cachedClass;
if (clazz != Object.class) {
if (clazz != null && value != null && value.getClass() == clazz) {
if (CompilerDirectives.inInterpreter()) {
return value;
} else {
return (T) CompilerDirectives.castExact(value, clazz);
}
} else {
CompilerDirectives.transferToInterpreterAndInvalidate();
if (clazz == null && value != null) {
cachedClass = value.getClass();
} else {
cachedClass = Object.class;
}
}
}
return value;
}
boolean isGeneric() {
return cachedClass == Object.class;
}
boolean isUninitialized() {
return cachedClass == null;
}
Class getCachedClass() {
return cachedClass;
}
@Override
public String toString() {
return toString(ValueProfile.class, cachedClass == null, cachedClass == Object.class,
String.format("value.getClass() == %s.class", cachedClass != null ? cachedClass.getSimpleName() : "null"));
}
}
}