src/jdk.internal.vm.ci/share/classes/jdk.vm.ci.meta/src/jdk/vm/ci/meta/SpeculationLog.java
8233113: ARM32: assert on UnsafeJlong mutex rank check
Reviewed-by: coleenp, dholmes
/*
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* 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.
*
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package jdk.vm.ci.meta;
import java.util.Map;
import java.util.function.Supplier;
/**
* Manages unique {@link SpeculationReason} objects that denote why a deoptimization occurred.
* Reasons are embedded in compiled code for a method. If the compiled code deoptimizes at a
* position associated with a {@link SpeculationReason}, the reason is added to a set of failed
* speculations associated with the method. A subsequent compilation of the method can query the
* failed speculations via a {@link SpeculationLog} to avoid making a speculation based on
* invalidated reasons. This avoids repeated deoptimizations.
*/
public interface SpeculationLog {
/**
* The specific attributes of a speculation that a compiler uses to denote a speculation in a
* compiled method. Typical attributes of a speculation are a bytecode position, type
* information about a variable being speculated on and an enum denoting the type of operation
* to which the speculation applies. A {@link SpeculationReason} is used as a key in a
* {@link Map} and so it must implement {@link Object#equals(Object)} and
* {@link Object#hashCode()} in terms of its attributes.
*
* A JVMCI implementation may serialize speculations for storage off heap (e.g. in native memory
* associated with an nmethod). For this reason, the attributes of a {@link SpeculationReason}
* are restricted to those supported by the {@code add...} methods of
* {@link SpeculationReasonEncoding}.
*/
public interface SpeculationReason {
/**
* Encodes the attributes of this reason using a {@link SpeculationReasonEncoding}. For
* efficiency, a {@link SpeculationReason} implementation should cache the returned value
* and return it for all subsequent calls to this method. This also underlines the
* requirement that the encoding for a specific reason instance should be stable.
*
* @param encodingSupplier source of a {@link SpeculationReasonEncoding}
* @return a {@link SpeculationReasonEncoding} that encodes all the attributes that uniquely
* identify this reason
*/
default SpeculationReasonEncoding encode(Supplier<SpeculationReasonEncoding> encodingSupplier) {
return null;
}
}
/**
* Provides a facility for encoding the attributes of a {@link SpeculationReason}. The encoding
* format is determined by the implementation of this interface.
*/
public interface SpeculationReasonEncoding {
void addByte(int value);
void addShort(int value);
void addInt(int value);
void addLong(long value);
void addMethod(ResolvedJavaMethod method);
void addType(ResolvedJavaType type);
void addString(String value);
default void addField(ResolvedJavaField field) {
addType(field.getDeclaringClass());
addInt(field.getModifiers());
addInt(field.getOffset());
}
}
/**
* Marker class that indicates that a speculation has no reason.
*/
final class NoSpeculationReason implements SpeculationReason {
}
class Speculation {
private final SpeculationReason reason;
public Speculation(SpeculationReason reason) {
this.reason = reason;
}
public SpeculationReason getReason() {
return reason;
}
@Override
public String toString() {
return reason.toString();
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Speculation) {
Speculation other = (Speculation) obj;
return reason.equals(other.reason);
}
return false;
}
@Override
public int hashCode() {
return getReason().hashCode();
}
}
Speculation NO_SPECULATION = new Speculation(new NoSpeculationReason());
/**
* Updates the set of failed speculations recorded in this log. This must be called before
* compilation.
*/
void collectFailedSpeculations();
/**
* If this method returns true, the compiler is allowed to {@link #speculate} with the given
* reason.
*/
boolean maySpeculate(SpeculationReason reason);
/**
* Registers a speculation performed by the compiler. The compiler must guard every call to this
* method for a specific reason with a call to {@link #maySpeculate(SpeculationReason)}.
*
* This API is subject to a benign race where a during the course of a compilation another
* thread might fail a speculation such that {@link #maySpeculate(SpeculationReason)} will
* return false but an earlier call returned true. This method will still return a working
* {@link Speculation} in that case but the compile will eventually be invalidated and the
* compile attempted again without the now invalid speculation.
*
* @param reason an object representing the reason for the speculation
* @return a compiler constant encapsulating the provided reason. It is usually passed as an
* argument to the deoptimization function.
*/
Speculation speculate(SpeculationReason reason);
/**
* Returns if this log has speculations.
*
* @return true if there are speculations, false otherwise
*/
boolean hasSpeculations();
/**
* Given a {@link JavaConstant} previously returned from
* {@link MetaAccessProvider#encodeSpeculation(Speculation)} return the original
* {@link Speculation} object.
*/
Speculation lookupSpeculation(JavaConstant constant);
}