SpeculationLog.java revision 12651:6ef01bd40ce2 
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23package jdk.vm.ci.meta;
24
25/**
26 * Manages unique deoptimization reasons. Reasons are embedded in compiled code and can be
27 * invalidated at run time. Subsequent compilations then should not speculate again on such
28 * invalidated reasons to avoid repeated deoptimization.
29 *
30 * All methods of this interface are called by the compiler. There is no need for API to register
31 * failed speculations during deoptimization, since every VM has different needs there.
32 */
33public interface SpeculationLog {
34
35    /**
36     * Marker interface for speculation objects that can be added to the speculation log.
37     */
38    public interface SpeculationReason {
39    }
40
41    /**
42     * Must be called before compilation, i.e., before a compiler calls {@link #maySpeculate}.
43     */
44    void collectFailedSpeculations();
45
46    /**
47     * If this method returns true, the compiler is allowed to {@link #speculate} with the given
48     * reason.
49     */
50    boolean maySpeculate(SpeculationReason reason);
51
52    /**
53     * Registers a speculation that was performed by the compiler.
54     *
55     * @return A compiler constant encapsulating the provided reason. It is usually passed as an
56     *         argument to the deoptimization function.
57     */
58    JavaConstant speculate(SpeculationReason reason);
59
60    /**
61     * Returns if this log has speculations.
62     *
63     * @return true if there are speculations, false otherwise
64     */
65    boolean hasSpeculations();
66}
67