ConstantPool.java revision 12657:6ef01bd40ce2 
1/*
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
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23package jdk.vm.ci.meta;
24
25/**
26 * Represents the runtime representation of the constant pool that is used by the compiler when
27 * parsing bytecode. Provides methods to look up a constant pool entry without performing
28 * resolution. They are used during compilation.
29 */
30public interface ConstantPool {
31
32    /**
33     * Returns the number of entries the constant pool.
34     *
35     * @return number of entries in the constant pool
36     */
37    int length();
38
39    /**
40     * Ensures that the type referenced by the specified constant pool entry is loaded and
41     * initialized. This can be used to compile time resolve a type. It works for field, method, or
42     * type constant pool entries.
43     *
44     * @param cpi the index of the constant pool entry that references the type
45     * @param opcode the opcode of the instruction that references the type
46     */
47    void loadReferencedType(int cpi, int opcode);
48
49    /**
50     * Looks up a reference to a field. If {@code opcode} is non-negative, then resolution checks
51     * specific to the bytecode it denotes are performed if the field is already resolved. Checks
52     * for some bytecodes require the method that contains the bytecode to be specified. Should
53     * any of these checks fail, an unresolved field reference is returned.
54     *
55     * @param cpi the constant pool index
56     * @param opcode the opcode of the instruction for which the lookup is being performed or
57     *            {@code -1}
58     * @param method the method for which the lookup is being performed
59     * @return a reference to the field at {@code cpi} in this pool
60     * @throws ClassFormatError if the entry at {@code cpi} is not a field
61     */
62    JavaField lookupField(int cpi, ResolvedJavaMethod method, int opcode);
63
64    /**
65     * Looks up a reference to a method. If {@code opcode} is non-negative, then resolution checks
66     * specific to the bytecode it denotes are performed if the method is already resolved. Should
67     * any of these checks fail, an unresolved method reference is returned.
68     *
69     * @param cpi the constant pool index
70     * @param opcode the opcode of the instruction for which the lookup is being performed or
71     *            {@code -1}
72     * @return a reference to the method at {@code cpi} in this pool
73     * @throws ClassFormatError if the entry at {@code cpi} is not a method
74     */
75    JavaMethod lookupMethod(int cpi, int opcode);
76
77    /**
78     * Looks up a reference to a type. If {@code opcode} is non-negative, then resolution checks
79     * specific to the bytecode it denotes are performed if the type is already resolved. Should any
80     * of these checks fail, an unresolved type reference is returned.
81     *
82     * @param cpi the constant pool index
83     * @param opcode the opcode of the instruction for which the lookup is being performed or
84     *            {@code -1}
85     * @return a reference to the compiler interface type
86     */
87    JavaType lookupType(int cpi, int opcode);
88
89    /**
90     * Looks up an Utf8 string.
91     *
92     * @param cpi the constant pool index
93     * @return the Utf8 string at index {@code cpi} in this constant pool
94     */
95    String lookupUtf8(int cpi);
96
97    /**
98     * Looks up a method signature.
99     *
100     * @param cpi the constant pool index
101     * @return the method signature at index {@code cpi} in this constant pool
102     */
103    Signature lookupSignature(int cpi);
104
105    /**
106     * Looks up a constant at the specified index.
107     *
108     * @param cpi the constant pool index
109     * @return the {@code Constant} or {@code JavaType} instance representing the constant pool
110     *         entry
111     */
112    Object lookupConstant(int cpi);
113
114    /**
115     * Looks up the appendix at the specified index.
116     *
117     * @param cpi the constant pool index
118     * @param opcode the opcode of the instruction for which the lookup is being performed or
119     *            {@code -1}
120     * @return the appendix if it exists and is resolved or {@code null}
121     */
122    JavaConstant lookupAppendix(int cpi, int opcode);
123}
124