/*
* Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.c1x.ir;
import java.util.*;
import com.sun.c1x.*;
import com.sun.c1x.value.*;
import com.sun.cri.ci.*;
/**
* Denotes an instruction node in the IR, which is a {@link Value} that
* can be added to a basic block (whereas other {@link Value} nodes such as {@link Phi} and
* {@link Local} cannot be added to basic blocks).
*
* Subclasses of instruction represent arithmetic and object operations,
* control flow operators, phi statements, method calls, the start of basic blocks, and
* the end of basic blocks.
*
* Instruction nodes are chained together in a basic block through the embedded
* {@link Instruction#next} field. An Instruction may also have a list of {@link ExceptionHandler}s.
*/
public abstract class Instruction extends Value {
public static final int INVOCATION_ENTRY_BCI = -1; // XXX: not currently used
public static final int SYNCHRONIZATION_ENTRY_BCI = -1;
/**
* Index of bytecode that generated this node when appended in a basic block.
* Negative values indicate special cases.
*/
private int bci;
/**
* Links to next instruction in a basic block or to {@code} itself if not in a block.
*/
private Instruction next = this;
/**
* List of associated exception handlers.
*/
private List<ExceptionHandler> exceptionHandlers = ExceptionHandler.ZERO_HANDLERS;
/**
* Constructs a new instruction with the specified value type.
* @param kind the value type for this instruction
*/
public Instruction(CiKind kind) {
super(kind);
C1XMetrics.HIRInstructions++;
}
/**
* Gets the bytecode index of this instruction.
* @return the bytecode index of this instruction
*/
public final int bci() {
return bci;
}
/**
* Sets the bytecode index of this instruction.
* @param bci the new bytecode index for this instruction
*/
public final void setBCI(int bci) {
assert bci >= 0 || bci == SYNCHRONIZATION_ENTRY_BCI;
this.bci = bci;
}
/**
* Checks whether this instruction has already been added to its basic block.
* @return {@code true} if this instruction has been added to the basic block containing it
*/
public final boolean isAppended() {
return next != this;
}
/**
* Gets the next instruction after this one in the basic block, or {@code null}
* if this instruction is the end of a basic block.
* @return the next instruction after this one in the basic block
*/
public final Instruction next() {
if (next == this) {
return null;
}
return next;
}
/**
* Sets the next instruction for this instruction. Note that it is illegal to
* set the next field of a phi, block end, or local instruction.
* @param next the next instruction
* @param bci the bytecode index of the next instruction
* @return the new next instruction
*/
public final Instruction setNext(Instruction next, int bci) {
this.next = next;
if (next != null) {
assert !(this instanceof BlockEnd);
next.setBCI(bci);
if (next.next == next) {
next.next = null;
}
}
return next;
}
/**
* Re-sets the next instruction for this instruction. Note that it is illegal to
* set the next field of a phi, block end, or local instruction.
* @param next the next instruction
* @return the new next instruction
*/
public final Instruction resetNext(Instruction next) {
if (next != null) {
assert !(this instanceof BlockEnd);
this.next = next;
}
return next;
}
/**
* Gets the instruction preceding this instruction in the specified basic block.
* Note that instructions do not directly refer to their previous instructions,
* and therefore this operation much search from the beginning of the basic
* block, thereby requiring time linear in the size of the basic block in the worst
* case. Use with caution!
* @param block the basic block that contains this instruction
* @return the instruction before this instruction in the basic block
*/
public final Instruction prev(BlockBegin block) {
Instruction p = null;
Instruction q = block;
while (q != this) {
assert q != null : "this instruction is not in the specified basic block";
p = q;
q = q.next();
}
return p;
}
@Override
public BlockBegin block() {
// TODO(tw): Make this more efficient.
Instruction cur = this;
while (!(cur instanceof BlockEnd)) {
cur = cur.next;
}
return ((BlockEnd) cur).begin;
}
/**
* Gets the list of exception handlers associated with this instruction.
* @return the list of exception handlers for this instruction
*/
public final List<ExceptionHandler> exceptionHandlers() {
return exceptionHandlers;
}
/**
* Sets the list of exception handlers for this instruction.
* @param exceptionHandlers the exception handlers
*/
public final void setExceptionHandlers(List<ExceptionHandler> exceptionHandlers) {
this.exceptionHandlers = exceptionHandlers;
}
/**
* Compute the value number of this Instruction. Local and global value numbering
* optimizations use a hash map, and the value number provides a hash code.
* If the instruction cannot be value numbered, then this method should return
* {@code 0}.
* @return the hashcode of this instruction
*/
public int valueNumber() {
return 0;
}
/**
* Checks that this instruction is equal to another instruction for the purposes
* of value numbering.
* @param i the other instruction
* @return {@code true} if this instruction is equivalent to the specified
* instruction w.r.t. value numbering
*/
public boolean valueEqual(Instruction i) {
return false;
}
/**
* Gets the name of this instruction as a string.
* @return the name of this instruction
*/
public final String name() {
return getClass().getSimpleName();
}
/**
* Tests whether this instruction can trap. This is conservative; it does not take
* into account analysis results that may eliminate the possibility of this
* instruction from trapping.
*
* @return {@code true} if this instruction can cause a trap.
*/
public boolean canTrap() {
return false;
}
/**
* Apply the specified closure to all the values of this instruction, including
* input values, state values, and other values.
* @param closure the closure to apply
*/
public final void allValuesDo(ValueClosure closure) {
inputValuesDo(closure);
FrameState stateBefore = stateBefore();
if (stateBefore != null) {
stateBefore.valuesDo(closure);
}
FrameState stateAfter = stateAfter();
if (stateAfter != null) {
stateAfter.valuesDo(closure);
}
}
/**
* Gets the state before the instruction, if it is recorded.
* @return the state before the instruction
*/
public FrameState stateBefore() {
return null;
}
/**
* Gets the state after the instruction, if it is recorded. Typically only
* instances of {@link BlockEnd} have a non-null state after.
* @return the state after the instruction
*/
public FrameState stateAfter() {
return null;
}
}