13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.classfile.attribute;
27
28 import java.lang.classfile.ClassFile;
29 import java.lang.classfile.Label;
30 import java.lang.classfile.Opcode;
31 import java.lang.classfile.constantpool.ClassEntry;
32 import java.lang.classfile.instruction.BranchInstruction;
33 import java.lang.constant.ClassDesc;
34 import java.util.List;
35
36 import jdk.internal.classfile.impl.StackMapDecoder;
37 import jdk.internal.classfile.impl.TemporaryConstantPool;
38
39 /**
40 * Models a stack map frame in a {@link StackMapTableAttribute StackMapTable}
41 * attribute (JVMS {@jvms 4.7.4}). A stack map frame must appear at the
42 * beginning of each basic block in a method (JVMS {@jvms 4.10.1}).
43 *
44 * @apiNote
45 * In general, a stack map frame should be defined for each target of a
46 * {@link BranchInstruction}, or unreachable code right after an unconditional
47 * branch instruction like {@link Opcode#GOTO goto}. The automatic stack map
48 * generation cannot handle unreachable code right after an unconditional jump;
49 * The {@link ClassFile.DeadCodeOption} allows substituting such code, or
50 * advanced users can provide their own stack maps for dead code.
51 *
52 * @see StackMapTableAttribute#entries()
60 /**
61 * {@return the raw {@code u1 frame_type}}
62 */
63 int frameType();
64
65 /**
66 * {@return the frame target label}
67 */
68 Label target();
69
70 /**
71 * {@return the expanded local variable types}
72 */
73 List<VerificationTypeInfo> locals();
74
75 /**
76 * {@return the expanded operand stack types}
77 */
78 List<VerificationTypeInfo> stack();
79
80 /**
81 * {@return a new stack map frame}
82 *
83 * @param target the location of the frame
84 * @param locals the complete list of frame locals
85 * @param stack the complete frame stack
86 */
87 public static StackMapFrameInfo of(Label target,
88 List<VerificationTypeInfo> locals,
89 List<VerificationTypeInfo> stack) {
90 return new StackMapDecoder.StackMapFrameImpl(255, target, locals, stack);
91 }
92
93 /**
94 * The type of a stack or local variable value.
95 *
96 * @see #locals()
97 * @see #stack()
98 * @jvms 4.7.4 The {@code StackMapTable} Attribute
99 * @since 24
100 */
101 sealed interface VerificationTypeInfo {
102
103 /** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#TOP TOP}. */
104 int ITEM_TOP = 0;
105
106 /** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#INTEGER INTEGER}. */
107 int ITEM_INTEGER = 1;
108
109 /** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#FLOAT FLOAT}. */
110 int ITEM_FLOAT = 2;
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.classfile.attribute;
27
28 import java.lang.classfile.ClassFile;
29 import java.lang.classfile.Label;
30 import java.lang.classfile.Opcode;
31 import java.lang.classfile.constantpool.ClassEntry;
32 import java.lang.classfile.instruction.BranchInstruction;
33 import java.lang.classfile.constantpool.NameAndTypeEntry;
34 import java.lang.constant.ClassDesc;
35 import java.util.List;
36
37 import jdk.internal.classfile.impl.StackMapDecoder;
38 import jdk.internal.classfile.impl.TemporaryConstantPool;
39
40 /**
41 * Models a stack map frame in a {@link StackMapTableAttribute StackMapTable}
42 * attribute (JVMS {@jvms 4.7.4}). A stack map frame must appear at the
43 * beginning of each basic block in a method (JVMS {@jvms 4.10.1}).
44 *
45 * @apiNote
46 * In general, a stack map frame should be defined for each target of a
47 * {@link BranchInstruction}, or unreachable code right after an unconditional
48 * branch instruction like {@link Opcode#GOTO goto}. The automatic stack map
49 * generation cannot handle unreachable code right after an unconditional jump;
50 * The {@link ClassFile.DeadCodeOption} allows substituting such code, or
51 * advanced users can provide their own stack maps for dead code.
52 *
53 * @see StackMapTableAttribute#entries()
61 /**
62 * {@return the raw {@code u1 frame_type}}
63 */
64 int frameType();
65
66 /**
67 * {@return the frame target label}
68 */
69 Label target();
70
71 /**
72 * {@return the expanded local variable types}
73 */
74 List<VerificationTypeInfo> locals();
75
76 /**
77 * {@return the expanded operand stack types}
78 */
79 List<VerificationTypeInfo> stack();
80
81 /**
82 * {@return the expanded unset fields}
83 *
84 * @see <a href="https://cr.openjdk.org/~dlsmith/jep401/jep401-20241108/specs/value-objects-jvms.html">Specs</a>
85 */
86 List<NameAndTypeEntry> unsetFields();
87
88 /**
89 * {@return a new stack map frame}
90 *
91 * @param target the location of the frame
92 * @param locals the complete list of frame locals
93 * @param stack the complete frame stack
94 */
95 public static StackMapFrameInfo of(Label target,
96 List<VerificationTypeInfo> locals,
97 List<VerificationTypeInfo> stack) {
98
99 return of(target, locals, stack, List.of());
100 }
101
102 /**
103 * {@return a new stack map frame}
104 * @param target the location of the frame
105 * @param locals the complete list of frame locals
106 * @param stack the complete frame stack
107 * @param unsetFields the complete list of unset fields
108 */
109 public static StackMapFrameInfo of(Label target,
110 List<VerificationTypeInfo> locals,
111 List<VerificationTypeInfo> stack,
112 List<NameAndTypeEntry> unsetFields) {
113
114 return new StackMapDecoder.StackMapFrameImpl(255, target, locals, stack, unsetFields);
115 }
116
117 /**
118 * The type of a stack or local variable value.
119 *
120 * @see #locals()
121 * @see #stack()
122 * @jvms 4.7.4 The {@code StackMapTable} Attribute
123 * @since 24
124 */
125 sealed interface VerificationTypeInfo {
126
127 /** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#TOP TOP}. */
128 int ITEM_TOP = 0;
129
130 /** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#INTEGER INTEGER}. */
131 int ITEM_INTEGER = 1;
132
133 /** The {@link #tag() tag} for verification type info {@link SimpleVerificationTypeInfo#FLOAT FLOAT}. */
134 int ITEM_FLOAT = 2;
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