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author | Lukas Stadler <lukas.stadler@jku.at> |
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date | Fri, 06 May 2011 10:25:37 +0200 |
parents | 4a016ff4d2df |
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/* * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.sun.c1x.gen; import com.sun.c1x.alloc.OperandPool.*; import com.sun.c1x.ir.*; import com.sun.c1x.util.*; import com.sun.cri.ci.*; /** * A helper utility for loading the {@linkplain Value#operand() result} * of an instruction for use by another instruction. This helper takes * into account the specifics of the consuming instruction such as whether * it requires the input operand to be in memory or a register, any * register size requirements of the input operand, and whether the * usage has the side-effect of overwriting the input operand. To satisfy * these constraints, an intermediate operand may be created and move * instruction inserted to copy the output of the producer instruction * into the intermediate operand. * * @author Marcelo Cintra * @author Thomas Wuerthinger * @author Doug Simon */ public class LIRItem { /** * The instruction whose usage by another instruction is being modeled by this object. * An instruction {@code x} uses instruction {@code y} if the {@linkplain Value#operand() result} * of {@code y} is an input operand of {@code x}. */ public Value instruction; /** * The LIR context of this helper object. */ private final LIRGenerator gen; /** * The operand holding the result of this item's {@linkplain #instruction}. */ private CiValue resultOperand; /** * Denotes if the use of the instruction's {@linkplain #resultOperand result operand} * overwrites the value in the operand. That is, the use both uses and defines the * operand. In this case, an {@linkplain #intermediateOperand intermediate operand} * is created for the use so that other consumers of this item's {@linkplain #instruction} * are not impacted. */ private boolean destructive; /** * @see #destructive */ private CiValue intermediateOperand; public LIRItem(Value instruction, LIRGenerator gen) { this.gen = gen; this.instruction = instruction; resultOperand = gen.makeOperand(instruction); intermediateOperand = CiValue.IllegalValue; } public void loadForStore(CiKind kind) { if (gen.canStoreAsConstant(instruction, kind)) { resultOperand = instruction.operand(); if (!resultOperand.isConstant()) { resultOperand = instruction.asConstant(); } } else if (kind == CiKind.Byte || kind == CiKind.Boolean) { loadByteItem(); } else { loadItem(); } } public CiValue result() { assert !destructive || !resultOperand.isRegister() : "shouldn't use setDestroysRegister with physical registers"; if (destructive && (resultOperand.isVariable() || resultOperand.isConstant())) { if (intermediateOperand.isIllegal()) { intermediateOperand = gen.newVariable(instruction.kind); gen.lir.move(resultOperand, intermediateOperand); } return intermediateOperand; } else { return resultOperand; } } public void setDestroysRegister() { destructive = true; } /** * Determines if the operand is in a stack slot. */ public boolean isStack() { return resultOperand.isAddress() || resultOperand.isStackSlot(); } /** * Determines if the operand is in a register or may be * resolved to a register by the register allocator. */ public boolean isRegisterOrVariable() { return resultOperand.isVariableOrRegister(); } public void loadByteItem() { if (gen.compilation.target.arch.isX86()) { loadItem(); CiValue res = result(); if (!res.isVariable() || !gen.operands.mustBeByteRegister(res)) { // make sure that it is a byte register assert !instruction.kind.isFloat() && !instruction.kind.isDouble() : "can't load floats in byte register"; CiValue reg = gen.operands.newVariable(CiKind.Byte, VariableFlag.MustBeByteRegister); gen.lir.move(res, reg); resultOperand = reg; } } else if (gen.compilation.target.arch.isSPARC()) { loadItem(); } else { Util.shouldNotReachHere(); } } public void loadNonconstant() { assert gen.compilation.target.arch.isX86(); CiValue r = instruction.operand(); if (r.isConstant()) { resultOperand = r; } else { loadItem(); } } private void setResult(CiVariable operand) { gen.setResult(instruction, operand); resultOperand = operand; } /** * Creates an operand containing the result of {@linkplain #instruction input instruction}. */ public void loadItem() { if (result().isIllegal()) { // update the item's result resultOperand = instruction.operand(); } CiValue result = result(); if (!result.isVariableOrRegister()) { CiVariable operand; operand = gen.newVariable(instruction.kind); gen.lir.move(result, operand); if (result.isConstant()) { resultOperand = operand; } else { setResult(operand); } } } @Override public String toString() { return result().toString(); } }