1 cananian 1.1.2.1 // LocationFactory.java, created Tue Oct 12 19:06:17 1999 by cananian
2 cananian 1.1.2.1 // Copyright (C) 1999 C. Scott Ananian <cananian@alumni.princeton.edu>
3 cananian 1.1.2.1 // Licensed under the terms of the GNU GPL; see COPYING for details.
4 cananian 1.1.2.1 package harpoon.Backend.Generic;
5 cananian 1.1.2.1
6 cananian 1.1.2.2 import harpoon.ClassFile.HCodeElement;
7 cananian 1.1.2.1 import harpoon.ClassFile.HData;
8 cananian 1.1.2.1 import harpoon.IR.Tree.Exp;
9 cananian 1.1.2.2 import harpoon.IR.Tree.TreeFactory;
10 cananian 1.1.2.2 import harpoon.IR.Tree.Type;
11 cananian 1.1.2.1 /**
12 cananian 1.1.2.2 * The <code>LocationFactory</code> interface provides a means for
13 cananian 1.1.2.2 * the runtime system to get access to some global storage for its
14 cananian 1.1.2.2 * use. For example, the memory manager may might to store pointer
15 cananian 1.1.2.2 * to the current top-of-heap and top-of-memory in some place accessible
16 cananian 1.1.2.2 * by every method. The locations returned may be global registers
17 cananian 1.1.2.2 * (in which case the <code>Generic.LocationFactory</code> must coordinate
18 cananian 1.1.2.2 * with <code>Generic.RegFileInfo</code> to ensure those registers
19 cananian 1.1.2.2 * are not used for other purposes by the register allocator) or
20 cananian 1.1.2.2 * static locations in memory (useful on register-constrained machines).
21 cananian 1.1.2.2 * If static storage is allocated, the <code>makeLocationData()</code>
22 cananian 1.1.2.2 * method will generate an <code>HData</code> containing a label and
23 cananian 1.1.2.2 * the appropriate declaration for the storage; otherwise it will
24 cananian 1.1.2.2 * return an empty <code>HData</code>.
25 cananian 1.1.2.1 *
26 cananian 1.1.2.1 * @author C. Scott Ananian <cananian@alumni.princeton.edu>
27 salcianu 1.3 * @version $Id: LocationFactory.java,v 1.3 2003/04/19 01:03:44 salcianu Exp $
28 cananian 1.1.2.1 */
29 salcianu 1.3 public interface LocationFactory extends java.io.Serializable {
30 cananian 1.1.2.3 /** The <code>Location</code>s returned by the
31 cananian 1.1.2.3 * <code>LocationFactory</code> allocation function
32 cananian 1.1.2.2 * are opaque data structures that permit only the creation of
33 cananian 1.1.2.2 * an accessor fragment in Tree form.
34 cananian 1.1.2.2 */
35 cananian 1.1.2.2 public static interface Location {
36 cananian 1.1.2.2 /** Return a <code>Tree.Exp</code> which can be used to address
37 cananian 1.1.2.2 * the contents of this <code>Location</code> for a fetch or
38 cananian 1.1.2.2 * set operation. For a global register, the returned value
39 cananian 1.1.2.2 * will typically be an instance of <code>Tree.TEMP</code>;
40 cananian 1.1.2.2 * for a memory location one would expect an instance of
41 cananian 1.1.2.2 * <code>Tree.MEM</code>. The accessor may return any valid
42 cananian 1.1.2.2 * fragment of Tree code, though. As Tree form may not
43 cananian 1.1.2.2 * reuse subtrees, a new <code>Tree.Exp</code> object should
44 cananian 1.1.2.2 * be returned every time this method is called.<p>
45 cananian 1.1.2.2 * The given <code>TreeFactory</code> is used to create
46 cananian 1.1.2.2 * the accessor fragment.
47 cananian 1.1.2.2 */
48 cananian 1.1.2.2 Exp makeAccessor(TreeFactory tf, HCodeElement source);
49 cananian 1.1.2.2 }
50 cananian 1.1.2.2 /** Allocate a global location of the specified type and return
51 cananian 1.1.2.2 * a handle to it. <strong>This method may not be called after
52 cananian 1.1.2.2 * <code>makeLocationData()</code> has been invoked</strong>. It
53 cananian 1.1.2.2 * is suggested that this constraint is checked in any
54 cananian 1.1.2.2 * implementation using a boolean flag to help ensure correctness.
55 cananian 1.1.2.2 * @param type a <code>IR.Tree.Type</code> specifying the type
56 cananian 1.1.2.2 * of location to allocate.
57 cananian 1.1.2.2 */
58 cananian 1.1.2.2 Location allocateLocation(int type);
59 cananian 1.1.2.2 /** Create an <code>HData</code> object that allocates static space
60 cananian 1.1.2.2 * for any allocated locations which need it.
61 cananian 1.1.2.2 * <strong>The <code>allocateLocation</code> method may not be
62 cananian 1.1.2.2 * called after this method has been invoked</strong>.
63 cananian 1.1.2.2 * @param f the <code>Generic.Frame</code> to which the
64 cananian 1.1.2.2 * <code>HData</code> will belong.
65 cananian 1.1.2.2 */
66 cananian 1.1.2.2 HData makeLocationData(Frame f);
67 cananian 1.2 }