com.oracle.svm.core.code

Class CodeInfoDecoder

java.lang.Object

com.oracle.svm.core.code.CodeInfoDecoder

public final class CodeInfoDecoder
extends Object

Decodes the metadata for compiled code. The data is an encoded byte stream to make it as compact as possible, but still allow fast constant time access. The encoding consists of entries with the following structure:

 u1 entryFlags
 u1 deltaIP
 [s1|s2|s4 frameSizeEncoding]
 [s1|s2|s4 exceptionOffset]
 [u2|u4 referenceMapIndex]
 [s4 deoptFrameInfoIndex]
 

The first byte, entryFlags, encodes which of the optional data fields are present and what size they have. The size of the whole entry can be computed from just this byte, which allows fast iteration of the table. The deltaIP is the difference of the IP for this entry and the next entry. The first entry always corresponds to IP zero. This table structure allows linear search for the entry of a given IP. An index is used to turn this into a constant time lookup. The index stores the entry offset for every IP at the given granularity.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CodeInfoDecoder.MethodDescriptor
static class	CodeInfoDecoder.Options

Method Summary

Modifier and Type	Method and Description
static Executable[]	getAllMethodMetadata()
static Target_jdk_internal_reflect_ConstantPool	getMetadataPseudoConstantPool()
static org.graalvm.collections.Pair<Executable[],CodeInfoDecoder.MethodDescriptor[]>	getMethodMetadata(DynamicHub declaringType)
static org.graalvm.collections.Pair<Executable[],CodeInfoDecoder.MethodDescriptor[]>	getMethodMetadata(int typeID, boolean complete) The metadata for methods in the image is split into two arrays: one for the index and the other for data.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getMethodMetadata

public static org.graalvm.collections.Pair<Executable[],CodeInfoDecoder.MethodDescriptor[]> getMethodMetadata(DynamicHub declaringType)

getAllMethodMetadata

public static Executable[] getAllMethodMetadata()

getMethodMetadata

public static org.graalvm.collections.Pair<Executable[],CodeInfoDecoder.MethodDescriptor[]> getMethodMetadata(int typeID,
                                                                                                              boolean complete)

The metadata for methods in the image is split into two arrays: one for the index and the other for data. The index contains an array of integers pointing to offsets in the data, and indexed by type ID. The data array contains arrays of method metadata, ordered by type ID, such that all methods declared by a class are stored consecutively. The data for a method is stored in the following format:

 {
     int methodNameIndex;        // index in frameInfoSourceMethodNames ("" for constructors)
     int modifiers;
     int paramCount;
     {
         int paramTypeIndex;     // index in frameInfoSourceClasses
     } paramTypes[paramCount];
     int returnTypeIndex;        // index in frameInfoSourceClasses (void for constructors)
     int exceptionTypeCount;
     {
         int exceptionTypeIndex; // index in frameInfoSourceClasses
     } exceptionTypes[exceptionTypeCount];
     // Annotation encodings (see CodeInfoEncoder)
     int annotationsLength;
     byte[] annotationsEncoding[annotationsLength];
     int parameterAnnotationsLength;
     byte[] parameterAnnotationsEncoding[parameterAnnotationsLength];
 }
 

This method returns two arrays. The first one contains the desired method data, the second one contains the names and parameter types of methods shadowing methods declared in superclasses which therefore should not be returned by a call to getMethod(). This second array is only computed for reflection queries, not for method dumping.

getMetadataPseudoConstantPool

public static Target_jdk_internal_reflect_ConstantPool getMetadataPseudoConstantPool()