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package org.pkl.thirdparty.truffle.api.profiles;
import org.pkl.thirdparty.truffle.api.CompilerDirectives;
import org.pkl.thirdparty.truffle.api.HostCompilerDirectives;
import org.pkl.thirdparty.truffle.api.dsl.InlineSupport.InlineTarget;
import org.pkl.thirdparty.truffle.api.dsl.InlineSupport.IntField;
import org.pkl.thirdparty.truffle.api.dsl.InlineSupport.LongField;
import org.pkl.thirdparty.truffle.api.dsl.InlineSupport.RequiredField;
import org.pkl.thirdparty.truffle.api.nodes.Node;
/**
*
* InlinedLoopConditionProfiles are designed to profile the outcome of loop conditions. Loop
* profiles can be used to profile unpredictable loops as well as predictable loops. This profile is
* intended to be used in combination with Truffle DSL.
*
*
*
* Uncounted loop usage example:
*
*
* class LoopNode extends Node {
*
* abstract void execute();
*
* @Specialization
* void doDefault(@Cached InlinedLoopConditionProfile loopProfile) {
* // loop count cannot be predicted
* while (loopProfile.profile(this, Math.random() >= 0.9)) {
* // work
* }
* }
* }
*
*
*
*
*
* Counted loop usage example:
*
*
* class CountedLoopNode extends Node {
*
* abstract void execute(int length);
*
* @Specialization
* void doDefault(int length, @Cached InlinedLoopConditionProfile loopProfile) {
* // loop count can be predicted
* loopProfile.profileCounted(this, length);
* for (int i = 0; loopProfile.inject(this, i < length); i++) {
* // work
* }
* }
* }
*
*
* The advantage of using {@link #profileCounted(Node, long)} to using
* {@link #profile(Node, boolean)} is that it incurs less overhead in the interpreter. Using
* {@link InlinedLoopConditionProfile#inject(Node, boolean)} is a no-op in the interpreter while
* {@link #profile(Node, boolean)} needs to use a counter for each iteration.
*
* {@inheritDoc}
*
* @see InlinedConditionProfile
* @see InlinedCountingConditionProfile
* @see LoopConditionProfile
* @since 23.0
*/
public final class InlinedLoopConditionProfile extends InlinedProfile {
private static final InlinedLoopConditionProfile DISABLED;
static {
InlinedLoopConditionProfile profile = new InlinedLoopConditionProfile();
DISABLED = profile;
}
private final LongField trueCount;
private final IntField falseCount;
/**
* A constant holding the maximum value an {@code int} can have, 230-1. The sum of
* the true and false count must not overflow. This constant is used to check whether one of the
* counts does not exceed the required maximum value.
*/
static final int MAX_VALUE = 0x3fffffff;
private InlinedLoopConditionProfile() {
this.trueCount = null;
this.falseCount = null;
}
private InlinedLoopConditionProfile(InlineTarget target) {
this.trueCount = target.getPrimitive(0, LongField.class);
this.falseCount = target.getPrimitive(1, IntField.class);
}
/** @since 23.0 */
public boolean profile(Node node, boolean condition) {
if (trueCount == null) {
return condition;
}
// locals required to guarantee no overflow in multi-threaded environments
long trueCountLocal = trueCount.get(node);
int falseCountLocal = falseCount.get(node);
if (trueCountLocal == 0) {
// Deopt for never entering the loop.
if (condition) {
CompilerDirectives.transferToInterpreterAndInvalidate();
}
}
if (HostCompilerDirectives.inInterpreterFastPath()) {
if (condition) {
if (trueCountLocal < Long.MAX_VALUE) {
trueCount.set(node, trueCountLocal + 1);
}
} else {
if (falseCountLocal < Integer.MAX_VALUE) {
falseCount.set(node, falseCountLocal + 1);
}
}
// no branch probability calculation in the interpreter
return condition;
} else {
if (this != DISABLED) {
return CompilerDirectives.injectBranchProbability(calculateProbability(trueCountLocal, falseCountLocal), condition);
} else {
return condition;
}
}
}
/**
* Provides an alternative way to profile counted loops with less interpreter footprint. Please
* see {@link InlinedLoopConditionProfile} for an usage example.
*
* @see #inject(Node, boolean)
* @since 23.0
*/
public void profileCounted(Node node, long length) {
if (HostCompilerDirectives.inInterpreterFastPath() && this != DISABLED) {
long trueCountLocal = trueCount.get(node) + length;
if (trueCountLocal >= 0) { // don't write overflow values
trueCount.set(node, trueCountLocal);
int falseCountLocal = falseCount.get(node);
if (falseCountLocal < Integer.MAX_VALUE) {
falseCount.set(node, falseCountLocal + 1);
}
}
}
}
/**
* Provides an alternative way to profile counted loops with less interpreter footprint. Please
* see {@link InlinedLoopConditionProfile} for an usage example.
*
* @since 23.0
*/
public boolean inject(Node node, boolean condition) {
if (CompilerDirectives.inCompiledCode() && this != DISABLED) {
return CompilerDirectives.injectBranchProbability(calculateProbability(trueCount.get(node), falseCount.get(node)), condition);
} else {
return condition;
}
}
private static double calculateProbability(long trueCountLocal, int falseCountLocal) {
if (falseCountLocal == 0 && trueCountLocal == 0) {
/* Avoid division by zero if profile was never used. */
return 0.0;
} else {
return (double) trueCountLocal / (double) (trueCountLocal + falseCountLocal);
}
}
/**
* Returns true if the {@link #profile(Node, boolean)} method ever received a
* true value, otherwise false. For profiles with profiling disabled
* or {@link #getUncached() uncached} profiles this method always returns true.
*
* @since 23.0
*/
public boolean wasTrue(Node node) {
return getTrueCount(node) != 0;
}
/**
* Returns true if the {@link #profile(Node, boolean)} method ever received a
* false value, otherwise false. For profiles with profiling disabled
* or {@link #getUncached() uncached} profiles this method always returns true.
*
* @since 23.0
*/
public boolean wasFalse(Node node) {
return getFalseCount(node) != 0;
}
/**
* {@inheritDoc}
*
* @since 23.0
*/
@Override
public void disable(Node node) {
if (trueCount == null) {
return;
}
if (this.trueCount.get(node) == 0) {
this.trueCount.set(node, 1);
}
if (this.falseCount.get(node) == 0) {
this.falseCount.set(node, 1);
}
}
/**
* {@inheritDoc}
*
* @since 23.0
*/
@Override
public void reset(Node node) {
if (trueCount == null) {
return;
}
this.trueCount.set(node, 0);
this.falseCount.set(node, 0);
}
long getTrueCount(Node node) {
if (trueCount == null) {
return Integer.MAX_VALUE;
}
return trueCount.get(node);
}
int getFalseCount(Node node) {
if (trueCount == null) {
return Integer.MAX_VALUE;
}
return falseCount.get(node);
}
boolean isGeneric(Node node) {
if (trueCount == null) {
return true;
}
return getTrueCount(node) != 0 && getFalseCount(node) != 0;
}
boolean isUninitialized(Node node) {
if (trueCount == null) {
return false;
}
return getTrueCount(node) == 0 && getFalseCount(node) == 0;
}
/**
* {@inheritDoc}
*
* @since 23.0
*/
@Override
public String toString(Node node) {
if (trueCount == null) {
return toStringDisabled();
}
long t = trueCount.get(node);
int f = falseCount.get(node);
long sum = t + f;
String details = String.format("trueProbability=%s (trueCount=%s, falseCount=%s)", (double) t / (double) sum, t, f);
return toString(ConditionProfile.class, sum == 0, false, details);
}
/**
* Returns an inlined version of the profile. This version is automatically used by Truffle DSL
* node inlining.
*
* @since 23.0
*/
public static InlinedLoopConditionProfile inline(
@RequiredField(value = LongField.class)//
@RequiredField(value = IntField.class) InlineTarget target) {
if (Profile.isProfilingEnabled()) {
return new InlinedLoopConditionProfile(target);
} else {
return getUncached();
}
}
/**
* Returns the uncached version of the profile. The uncached version of a profile does not
* perform any profiling.
*
* @since 23.0
*/
public static InlinedLoopConditionProfile getUncached() {
return DISABLED;
}
}