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111 lines
3.1 KiB
111 lines
3.1 KiB
package jode;
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import sun.tools.java.*;
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/**
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* The LocalInfo represents a local variable of a method.
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* The problem is that two different local variables may use the same
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* slot. The current strategie is to make the range of a local variable
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* as small as possible.
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*
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* There may be more than one LocalInfo for a single local variable,
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* because the algorithm begins with totally disjunct variables and
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* then unifies locals. One of the local is then a shadow object which
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* calls the member functions of the other local.
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*/
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public class LocalInfo {
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private static int serialnr = 0;
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private int slot;
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private Identifier name;
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private Type type;
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private LocalInfo shadow;
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/**
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* Create a new local info. The name will be an identifier
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* of the form local_x__yyy, where x is the slot number and
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* yyy a unique number.
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* @param slot The slot of this variable.
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*/
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public LocalInfo(int slot) {
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name = null;
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type = MyType.tUnknown;
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this.slot = slot;
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}
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/**
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* Combines the LocalInfo with another. This will make this
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* a shadow object to the other local info. That is all member
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* functions will use the new local info instead of data in this
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* object. <p>
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* If this is called with ourself nothing will happen.
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* @param li the local info that we want to shadow.
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*/
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public void combineWith(LocalInfo li) {
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if (shadow != null)
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shadow.combineWith(li);
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li = li.getLocalInfo();
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if (this != li) {
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shadow = li;
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li.setType(type);
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}
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}
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/**
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* Get the real LocalInfo. This may be different from the
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* current object if this is a shadow local info.
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*/
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public LocalInfo getLocalInfo() {
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if (shadow != null)
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return shadow.getLocalInfo();
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return this;
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}
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/**
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* Get the name of this local.
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*/
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public Identifier getName() {
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if (shadow != null)
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return shadow.getName();
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if (name == null)
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name = Identifier.lookup("local_"+slot+"__"+serialnr++);
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return name;
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}
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/**
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* Set the name of this local.
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*/
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public void setName(Identifier name) {
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if (shadow != null)
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shadow.setName(name);
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else
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this.name = name;
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}
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/**
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* Get the type of this local.
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*/
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public Type getType() {
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if (shadow != null)
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return shadow.getType();
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return type;
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}
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/**
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* Sets a new information about the type of this local.
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* The type of the local is may be made more specific by this call.
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* @param The new type information to be set.
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* @return The new type of the local.
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*/
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public Type setType(Type newType) {
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if (shadow != null)
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return shadow.setType(newType);
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this.type = MyType.intersection(this.type, newType);
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if (this.type == MyType.tError)
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System.err.println("Type error in "+getName());
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return this.type;
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}
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public boolean isShadow() {
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return (shadow != null);
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}
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}
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