1 /*
2 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 import java.lang.reflect.code.*;
25 import java.lang.reflect.code.op.CoreOp;
26 import java.util.HashMap;
27 import java.util.function.BiConsumer;
28
29 import static java.lang.reflect.code.op.CoreOp.sub;
30 import static java.lang.reflect.code.analysis.Patterns.*;
31
32 public final class ExpressionElimination {
33 private ExpressionElimination() {
34 }
35
36 static OpPattern negP(Pattern operand) {
37 return opP(CoreOp.NegOp.class, operand);
38 }
39
40 static OpPattern addP(Pattern lhs, Pattern rhs) {
41 return opP(CoreOp.AddOp.class, lhs, rhs);
42 }
43
44 static OpPattern mulP(Pattern lhs, Pattern rhs) {
45 return opP(CoreOp.MulOp.class, lhs, rhs);
46 }
47
48 public static <T extends Op> T eliminate(T f) {
49 // Note expression elimination and other forms of analysis is simplified if first of all expressions
50 // are normalized e.g. when they have an operand that is a constant expression
51 // and the operation is associative such as add(0, x) -> add(x, 0)
52
53 var actions = multiMatch(new HashMap<Op.Result, BiConsumer<Block.Builder, Op>>(), f)
54 .pattern(mulP(_P(), valueP(constantP(0.0d))))
55 .pattern(mulP(valueP(constantP(0.0d)), _P()))
56 .pattern(addP(valueP(), constantP(0.0d)))
57 .pattern(addP(constantP(0.0d), valueP()))
58 .pattern(mulP(constantP(1.0d), valueP()))
59 .pattern(mulP(valueP(), constantP(1.0d)))
60 .target((ms, as) -> {
61 Value a = ms.matchedOperands().get(0);
62 as.put(ms.op().result(), (block, op) -> {
63 CopyContext cc = block.context();
64 cc.mapValue(ms.op().result(), cc.getValue(a));
65 });
66 return as;
67 })
68 // add(neg(x), y) -> sub(y, x)
69 .pattern(addP(negP(valueP()), valueP()))
70 .target((ms, as) -> {
71 Value x = ms.matchedOperands().get(0);
72 Value y = ms.matchedOperands().get(1);
73
74 as.put(ms.op().result(), (block, op) -> {
75 CopyContext cc = block.context();
76 Op.Result r = block.op(sub(cc.getValue(y), cc.getValue(x)));
77 cc.mapValue(ms.op().result(), r);
78 });
79 return as;
80 })
81 .matchThenApply();
82
83 // Eliminate
84 Op ef = f.transform(CopyContext.create(), (block, op) -> {
85 BiConsumer<Block.Builder, Op> a = actions.get(op.result());
86 if (a != null) {
87 a.accept(block, op);
88 } else {
89 block.op(op);
90 }
91 return block;
92 });
93
94 // Remove dead ops
95 ef = ef.transform(CopyContext.create(), (block, op) -> {
96 if (!(op instanceof Op.Pure) ||
97 !op.result().uses().isEmpty()) {
98 block.op(op);
99 }
100 return block;
101 });
102
103 @SuppressWarnings("unchecked")
104 T t = (T) ef;
105 return t;
106 }
107 }