/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.dx.ssa;
import com.android.dx.util.MutabilityControl;
import com.android.dx.rop.code.RegisterSpecSet;
import com.android.dx.rop.code.RegisterSpec;
import java.util.HashMap;
import java.util.List;
/**
* Container for local variable information for a particular {@link
* com.android.dx.ssa.SsaMethod}.
* Stolen from {@link com.android.dx.rop.code.LocalVariableInfo}.
*/
public class LocalVariableInfo extends MutabilityControl {
/** >= 0; the register count for the method */
private final int regCount;
/**
* non-null; {@link com.android.dx.rop.code.RegisterSpecSet} to use when indicating a block
* that has no locals; it is empty and immutable but has an appropriate
* max size for the method
*/
private final RegisterSpecSet emptySet;
/**
* non-null; array consisting of register sets representing the
* sets of variables already assigned upon entry to each block,
* where array indices correspond to block indices
*/
private final RegisterSpecSet[] blockStarts;
/** non-null; map from instructions to the variable each assigns */
private final HashMap<SsaInsn, RegisterSpec> insnAssignments;
/**
* Constructs an instance.
*
* @param method non-null; the method being represented by this instance
*/
public LocalVariableInfo(SsaMethod method) {
if (method == null) {
throw new NullPointerException("method == null");
}
List<SsaBasicBlock> blocks = method.getBlocks();
this.regCount = method.getRegCount();
this.emptySet = new RegisterSpecSet(regCount);
this.blockStarts = new RegisterSpecSet[blocks.size()];
this.insnAssignments =
new HashMap<SsaInsn, RegisterSpec>(/*hint here*/);
emptySet.setImmutable();
}
/**
* Sets the register set associated with the start of the block with
* the given index.
*
* @param index >= 0; the block index
* @param specs non-null; the register set to associate with the block
*/
public void setStarts(int index, RegisterSpecSet specs) {
throwIfImmutable();
if (specs == null) {
throw new NullPointerException("specs == null");
}
try {
blockStarts[index] = specs;
} catch (ArrayIndexOutOfBoundsException ex) {
// Translate the exception.
throw new IllegalArgumentException("bogus index");
}
}
/**
* Merges the given register set into the set for the block with the
* given index. If there was not already an associated set, then this
* is the same as calling {@link #setStarts}. Otherwise, this will
* merge the two sets and call {@link #setStarts} on the result of the
* merge.
*
* @param index >= 0; the block index
* @param specs non-null; the register set to merge into the start set
* for the block
* @return <code>true</code> if the merge resulted in an actual change
* to the associated set (including storing one for the first time) or
* <code>false</code> if there was no change
*/
public boolean mergeStarts(int index, RegisterSpecSet specs) {
RegisterSpecSet start = getStarts0(index);
boolean changed = false;
if (start == null) {
setStarts(index, specs);
return true;
}
RegisterSpecSet newStart = start.mutableCopy();
newStart.intersect(specs, true);
if (start.equals(newStart)) {
return false;
}
newStart.setImmutable();
setStarts(index, newStart);
return true;
}
/**
* Gets the register set associated with the start of the block
* with the given index. This returns an empty set with the appropriate
* max size if no set was associated with the block in question.
*
* @param index >= 0; the block index
* @return non-null; the associated register set
*/
public RegisterSpecSet getStarts(int index) {
RegisterSpecSet result = getStarts0(index);
return (result != null) ? result : emptySet;
}
/**
* Gets the register set associated with the start of the given
* block. This is just convenient shorthand for
* <code>getStarts(block.getLabel())</code>.
*
* @param block non-null; the block in question
* @return non-null; the associated register set
*/
public RegisterSpecSet getStarts(SsaBasicBlock block) {
return getStarts(block.getIndex());
}
/**
* Gets a mutable copy of the register set associated with the
* start of the block with the given index. This returns a
* newly-allocated empty {@link RegisterSpecSet} of appropriate
* max size if there is not yet any set associated with the block.
*
* @param index >= 0; the block index
* @return non-null; the associated register set
*/
public RegisterSpecSet mutableCopyOfStarts(int index) {
RegisterSpecSet result = getStarts0(index);
return (result != null) ?
result.mutableCopy() : new RegisterSpecSet(regCount);
}
/**
* Adds an assignment association for the given instruction and
* register spec. This throws an exception if the instruction
* doesn't actually perform a named variable assignment.
*
* <b>Note:</b> Although the instruction contains its own spec for
* the result, it still needs to be passed in explicitly to this
* method, since the spec that is stored here should always have a
* simple type and the one in the instruction can be an arbitrary
* {@link com.android.dx.rop.type.TypeBearer} (such as a constant value).
*
* @param insn non-null; the instruction in question
* @param spec non-null; the associated register spec
*/
public void addAssignment(SsaInsn insn, RegisterSpec spec) {
throwIfImmutable();
if (insn == null) {
throw new NullPointerException("insn == null");
}
if (spec == null) {
throw new NullPointerException("spec == null");
}
insnAssignments.put(insn, spec);
}
/**
* Gets the named register being assigned by the given instruction, if
* previously stored in this instance.
*
* @param insn non-null; instruction in question
* @return null-ok; the named register being assigned, if any
*/
public RegisterSpec getAssignment(SsaInsn insn) {
return insnAssignments.get(insn);
}
/**
* Gets the number of assignments recorded by this instance.
*
* @return >= 0; the number of assignments
*/
public int getAssignmentCount() {
return insnAssignments.size();
}
public void debugDump() {
for (int index = 0 ; index < blockStarts.length; index++) {
if (blockStarts[index] == null) {
continue;
}
if (blockStarts[index] == emptySet) {
System.out.printf("%04x: empty set\n", index);
} else {
System.out.printf("%04x: %s\n", index, blockStarts[index]);
}
}
}
/**
* Helper method, to get the starts for a index, throwing the
* right exception for range problems.
*
* @param index >= 0; the block index
* @return null-ok; associated register set or <code>null</code> if there
* is none
*/
private RegisterSpecSet getStarts0(int index) {
try {
return blockStarts[index];
} catch (ArrayIndexOutOfBoundsException ex) {
// Translate the exception.
throw new IllegalArgumentException("bogus index");
}
}
}
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