Mercurial > hg > graal-compiler
comparison graal/GraalCompiler/src/com/sun/c1x/opt/PhiSimplifier.java @ 2509:16b9a8b5ad39
Renamings Runtime=>GraalRuntime and Compiler=>GraalCompiler
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 27 Apr 2011 11:50:44 +0200 |
parents | graal/Compiler/src/com/sun/c1x/opt/PhiSimplifier.java@9ec15d6914ca |
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2508:fea94949e0a2 | 2509:16b9a8b5ad39 |
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1 /* | |
2 * Copyright (c) 2009, 2011, 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 package com.sun.c1x.opt; | |
24 | |
25 import com.sun.c1x.graph.IR; | |
26 import com.sun.c1x.ir.*; | |
27 import com.sun.c1x.value.*; | |
28 | |
29 /** | |
30 * The {@code PhiSimplifier} class is a helper class that can reduce phi instructions. | |
31 * | |
32 * @author Ben L. Titzer | |
33 */ | |
34 public final class PhiSimplifier implements BlockClosure { | |
35 | |
36 final IR ir; | |
37 final InstructionSubstituter subst; | |
38 | |
39 public PhiSimplifier(IR ir) { | |
40 this.ir = ir; | |
41 this.subst = new InstructionSubstituter(ir); | |
42 ir.startBlock.iterateAnyOrder(this, false); | |
43 subst.finish(); | |
44 } | |
45 | |
46 /** | |
47 * This method is called for each block and processes any phi statements in the block. | |
48 * @param block the block to apply the simplification to | |
49 */ | |
50 public void apply(BlockBegin block) { | |
51 FrameState state = block.stateBefore(); | |
52 for (int i = 0; i < state.stackSize(); i++) { | |
53 simplify(state.stackAt(i)); | |
54 } | |
55 for (int i = 0; i < state.localsSize(); i++) { | |
56 simplify(state.localAt(i)); | |
57 } | |
58 } | |
59 | |
60 Value simplify(Value x) { | |
61 if (x == null || !(x instanceof Phi)) { | |
62 return x; | |
63 } | |
64 Phi phi = (Phi) x; | |
65 if (phi.hasSubst()) { | |
66 // already substituted, but the subst could be a phi itself, so simplify | |
67 return simplify(subst.getSubst(phi)); | |
68 } else if (phi.checkFlag(Value.Flag.PhiCannotSimplify)) { | |
69 // already tried, cannot simplify this phi | |
70 return phi; | |
71 } else if (phi.checkFlag(Value.Flag.PhiVisited)) { | |
72 // break cycles in phis | |
73 return phi; | |
74 } else if (phi.isIllegal()) { | |
75 // don't bother with illegals | |
76 return phi; | |
77 } else { | |
78 // attempt to simplify the phi by recursively simplifying its operands | |
79 phi.setFlag(Value.Flag.PhiVisited); | |
80 Value phiSubst = null; | |
81 int max = phi.inputCount(); | |
82 boolean cannotSimplify = false; | |
83 for (int i = 0; i < max; i++) { | |
84 Value oldInstr = phi.inputAt(i); | |
85 | |
86 if (oldInstr == null || oldInstr.isIllegal() || oldInstr.isDeadPhi()) { | |
87 // if one operand is illegal, make the entire phi illegal | |
88 phi.makeDead(); | |
89 phi.clearFlag(Value.Flag.PhiVisited); | |
90 return phi; | |
91 } | |
92 | |
93 Value newInstr = simplify(oldInstr); | |
94 | |
95 if (newInstr == null || newInstr.isIllegal() || newInstr.isDeadPhi()) { | |
96 // if the subst instruction is illegal, make the entire phi illegal | |
97 phi.makeDead(); | |
98 phi.clearFlag(Value.Flag.PhiVisited); | |
99 return phi; | |
100 } | |
101 | |
102 // attempt to simplify this operand | |
103 if (!cannotSimplify) { | |
104 | |
105 if (newInstr != phi && newInstr != phiSubst) { | |
106 if (phiSubst == null) { | |
107 phiSubst = newInstr; | |
108 continue; | |
109 } | |
110 // this phi cannot be simplified | |
111 cannotSimplify = true; | |
112 } | |
113 } | |
114 } | |
115 if (cannotSimplify) { | |
116 phi.setFlag(Value.Flag.PhiCannotSimplify); | |
117 phi.clearFlag(Value.Flag.PhiVisited); | |
118 return phi; | |
119 } | |
120 | |
121 // successfully simplified the phi | |
122 assert phiSubst != null : "illegal phi function"; | |
123 phi.clearFlag(Value.Flag.PhiVisited); | |
124 subst.setSubst(phi, phiSubst); | |
125 return phiSubst; | |
126 } | |
127 } | |
128 } |