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70 lines
3.8 KiB
Java
70 lines
3.8 KiB
Java
/*
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* Copyright (c) 2023, 2025, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/**
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* <h2>Provides interfaces describing code instructions for the {@link java.lang.classfile} library.</h2>
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*
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* The {@code java.lang.classfile.instruction} package contains interfaces describing code instructions.
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* Implementations of these interfaces are immutable.
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* <p>
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* APIs in this package perform {@linkplain java.lang.classfile##checks null and unrepresentable argument checks},
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* unless otherwise noted.
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*
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* <h2 id="reading">Reading of instructions</h2>
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* Instructions and pseudo-instructions are usually accessed from a {@link CodeModel}, such as {@link CodeModel#forEach
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* CodeModel::forEach}, and categorized by pattern-matching.
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* <p>
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* When read from {@code class} files, instructions are lazily inflated; the contents of these instructions, besides the
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* bare structure, are not evaluated to speed up parsing. Instructions to users interest, such as those filtered by the
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* pattern matching, have their contents read on demand, to avoid unnecessary reading of unrelated instructions in a code
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* array.
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* <p>
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* Due to the lazy nature of {@code class} file parsing, {@link IllegalArgumentException} indicating malformed
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* {@code class} file data can be thrown at any method invocation. For example, an instruction object for a {@link
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* TypeCheckInstruction} may be obtained from a {@code CodeModel}, but the subsequent invocation of {@link
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* TypeCheckInstruction#type() .type()} may fail with {@code IllegalArgumentException} because the instruction refers
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* to a bad constant pool index.
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*
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* <h2 id="writing">Writing of instructions</h2>
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* Writing of instructions happen on {@link CodeBuilder}. The most basic way to write instructions is to pass an
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* instruction object to {@link CodeBuilder#with CodeBuilder::with}, which supports all valid instructions.
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* Yet, {@code CodeBuilder} provides a lot of {@linkplain CodeBuilder##instruction-factories convenience factory methods}
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* for easy creation of instructions, named by their mnemonic. These accessors are more concise, and often more
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* efficient at run-time than passing instruction objects.
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* <p>
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* Due to restrictions in the {@code class} file format, some instructions may not be representable in a {@code CodeBuilder}.
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* In some scenarios, such as for {@link BranchInstruction}, Class-File API options control if alternatives can be used
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* in code generation instead. Otherwise, they can be configured to fail-fast to ensure the parity of {@code CodeBuilder}
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* commands with the generated {@code code} array data.
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*
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* @jvms 6.5 Instructions
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* @since 24
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*/
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package java.lang.classfile.instruction;
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import java.lang.classfile.CodeBuilder;
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import java.lang.classfile.CodeModel;
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