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package org.graalvm.compiler.lir.alloc.trace;

import org.graalvm.compiler.core.common.alloc.Trace;
import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;

A collection of assertions that are assumed to hold in various places of the Trace Register
Allocation framework.
The main goal is to document pieces of code that rely on specific properties of traces. In case
an assumption is no longer valid, this makes it easy (assumed they are used correctly) to find
places that need changes.
/**
 * A collection of assertions that are assumed to hold in various places of the Trace Register
 * Allocation framework.
 *
 * The main goal is to document pieces of code that rely on specific properties of traces. In case
 * an assumption is no longer valid, this makes it easy (assumed they are used correctly) to find
 * places that need changes.
 */
final class TraceAssertions {

    
Asserts that variable indices are properly sorted.
/**
     * Asserts that variable indices are properly sorted.
     */
    public static boolean liveSetsAreSorted(GlobalLivenessInfo livenessInfo, AbstractBlockBase<?> block) {
        return isSorted(livenessInfo.getBlockIn(block)) && isSorted(livenessInfo.getBlockOut(block));
    }

    private static boolean isSorted(int[] live) {
        if (live.length == 0) {
            return true;
        }
        int current = live[0];
        for (int i = 1; i < live.length; i++) {
            int last = current;
            current = live[i];
            if (current <= last) {
                return false;
            }
        }
        return true;
    }

    
Asserts that a trace head has only a single predecessor. This is not true for every trace-building algorithm (for example TraceBuilder.SingleBlock). /**
     * Asserts that a trace head has only a single predecessor.
     *
     * This is not true for every trace-building algorithm (for example
     * {@link TraceBuilderPhase.TraceBuilder#SingleBlock}).
     */
    public static boolean singleHeadPredecessor(Trace trace) {
        return trace.getBlocks()[0].getPredecessorCount() == 1;
    }
}