1/*
2 * Copyright (c) 2015-2016 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2004-2005 The Regents of The University of Michigan
15 * Copyright (c) 2013 Advanced Micro Devices, Inc.
16 * All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Authors: Kevin Lim
42 * Steve Reinhardt
43 */
44
45#ifndef __CPU_O3_RENAME_MAP_HH__
46#define __CPU_O3_RENAME_MAP_HH__
47
48#include <iostream>
49#include <utility>
50#include <vector>
51
52#include "arch/types.hh"
53#include "config/the_isa.hh"
54#include "cpu/o3/free_list.hh"
55#include "cpu/o3/regfile.hh"
56#include "cpu/reg_class.hh"
57
58/**
59 * Register rename map for a single class of registers (e.g., integer
60 * or floating point). Because the register class is implicitly
61 * determined by the rename map instance being accessed, all
62 * architectural register index parameters and values in this class
63 * are relative (e.g., %fp2 is just index 2).
64 */
65class SimpleRenameMap
66{
67 private:
68 using Arch2PhysMap = std::vector<PhysRegIdPtr>;
69 /** The acutal arch-to-phys register map */
70 Arch2PhysMap map;
71
72 /**
73 * Pointer to the free list from which new physical registers
74 * should be allocated in rename()
75 */
76 SimpleFreeList *freeList;
77
78 /**
79 * The architectural index of the zero register. This register is
80 * mapped but read-only, so we ignore attempts to rename it via
81 * the rename() method. If there is no such register for this map
82 * table, it should be set to an invalid index so that it never
83 * matches.
84 */
85 RegId zeroReg;
86
87 public:
88
89 SimpleRenameMap();
90
91 ~SimpleRenameMap() {};
92
93 /**
94 * Because we have an array of rename maps (one per thread) in the CPU,
95 * it's awkward to initialize this object via the constructor.
96 * Instead, this method is used for initialization.
97 */
98 void init(unsigned size, SimpleFreeList *_freeList, RegIndex _zeroReg);
99
100 /**
101 * Pair of a physical register and a physical register. Used to
102 * return the physical register that a logical register has been
103 * renamed to, and the previous physical register that the same
104 * logical register was previously mapped to.
105 */
106 typedef std::pair<PhysRegIdPtr, PhysRegIdPtr> RenameInfo;
107
108 /**
109 * Tell rename map to get a new free physical register to remap
110 * the specified architectural register.
111 * @param arch_reg The architectural register to remap.
112 * @return A RenameInfo pair indicating both the new and previous
113 * physical registers.
114 */
115 RenameInfo rename(const RegId& arch_reg);
116
117 /**
118 * Look up the physical register mapped to an architectural register.
119 * @param arch_reg The architectural register to look up.
120 * @return The physical register it is currently mapped to.
121 */
122 PhysRegIdPtr lookup(const RegId& arch_reg) const
123 {
124 assert(arch_reg.flatIndex() <= map.size());
125 return map[arch_reg.flatIndex()];
126 }
127
128 /**
129 * Update rename map with a specific mapping. Generally used to
130 * roll back to old mappings on a squash.
131 * @param arch_reg The architectural register to remap.
132 * @param phys_reg The physical register to remap it to.
133 */
134 void setEntry(const RegId& arch_reg, PhysRegIdPtr phys_reg)
135 {
136 assert(arch_reg.flatIndex() <= map.size());
137 map[arch_reg.flatIndex()] = phys_reg;
138 }
139
140 /** Return the number of free entries on the associated free list. */
141 unsigned numFreeEntries() const { return freeList->numFreeRegs(); }
142};
143
144
145/**
146 * Unified register rename map for all classes of registers. Wraps a
147 * set of class-specific rename maps. Methods that do not specify a
148 * register class (e.g., rename()) take register ids,
149 * while methods that do specify a register class (e.g., renameInt())
150 * take register indices.
151 */
152class UnifiedRenameMap
153{
154 private:
155
156 /** The integer register rename map */
157 SimpleRenameMap intMap;
158
159 /** The floating-point register rename map */
160 SimpleRenameMap floatMap;
161
162 /** The condition-code register rename map */
163 SimpleRenameMap ccMap;
164
165 /**
166 * The register file object is used only to get PhysRegIdPtr
167 * on MiscRegs, as they are stored in it.
168 */
169 PhysRegFile *regFile;
170
171 public:
172
173 typedef SimpleRenameMap::RenameInfo RenameInfo;
174
175 /** Default constructor. init() must be called prior to use. */
176 UnifiedRenameMap() : regFile(nullptr) {};
177
178 /** Destructor. */
179 ~UnifiedRenameMap() {};
180
181 /** Initializes rename map with given parameters. */
182 void init(PhysRegFile *_regFile,
183 RegIndex _intZeroReg,
184 RegIndex _floatZeroReg,
185 UnifiedFreeList *freeList);
186
187 /**
188 * Tell rename map to get a new free physical register to remap
189 * the specified architectural register. This version takes a
190 * RegId and reads the appropriate class-specific rename table.
191 * @param arch_reg The architectural register id to remap.
192 * @return A RenameInfo pair indicating both the new and previous
193 * physical registers.
194 */
195 RenameInfo rename(const RegId& arch_reg)
196 {
197 switch (arch_reg.classValue()) {
198 case IntRegClass:
199 return intMap.rename(arch_reg);
200 case FloatRegClass:
201 return floatMap.rename(arch_reg);
202 case CCRegClass:
203 return ccMap.rename(arch_reg);
204 case MiscRegClass:
205 {
206 // misc regs aren't really renamed, just remapped
207 PhysRegIdPtr phys_reg = lookup(arch_reg);
208 // Set the new register to the previous one to keep the same
209 // mapping throughout the execution.
210 return RenameInfo(phys_reg, phys_reg);
211 }
212
213 default:
214 panic("rename rename(): unknown reg class %s\n",
215 arch_reg.className());
216 }
217 }
218
219 /**
220 * Look up the physical register mapped to an architectural register.
221 * This version takes a flattened architectural register id
222 * and calls the appropriate class-specific rename table.
223 * @param arch_reg The architectural register to look up.
224 * @return The physical register it is currently mapped to.
225 */
226 PhysRegIdPtr lookup(const RegId& arch_reg) const
227 {
228 switch (arch_reg.classValue()) {
229 case IntRegClass:
230 return intMap.lookup(arch_reg);
231
232 case FloatRegClass:
233 return floatMap.lookup(arch_reg);
234
235 case CCRegClass:
236 return ccMap.lookup(arch_reg);
237
238 case MiscRegClass:
239 // misc regs aren't really renamed, they keep the same
240 // mapping throughout the execution.
241 return regFile->getMiscRegId(arch_reg.flatIndex());
242
243 default:
244 panic("rename lookup(): unknown reg class %s\n",
245 arch_reg.className());
246 }
247 }
248
249 /**
250 * Update rename map with a specific mapping. Generally used to
251 * roll back to old mappings on a squash. This version takes a
252 * flattened architectural register id and calls the
253 * appropriate class-specific rename table.
254 * @param arch_reg The architectural register to remap.
255 * @param phys_reg The physical register to remap it to.
256 */
257 void setEntry(const RegId& arch_reg, PhysRegIdPtr phys_reg)
258 {
259 switch (arch_reg.classValue()) {
260 case IntRegClass:
261 assert(phys_reg->isIntPhysReg());
262 return intMap.setEntry(arch_reg, phys_reg);
263
264 case FloatRegClass:
265 assert(phys_reg->isFloatPhysReg());
266 return floatMap.setEntry(arch_reg, phys_reg);
267
268 case CCRegClass:
269 assert(phys_reg->isCCPhysReg());
270 return ccMap.setEntry(arch_reg, phys_reg);
271
272 case MiscRegClass:
273 // Misc registers do not actually rename, so don't change
274 // their mappings. We end up here when a commit or squash
275 // tries to update or undo a hardwired misc reg nmapping,
276 // which should always be setting it to what it already is.
277 assert(phys_reg == lookup(arch_reg));
278 return;
279
280 default:
281 panic("rename setEntry(): unknown reg class %s\n",
282 arch_reg.className());
283 }
284 }
285
286 /**
287 * Return the minimum number of free entries across all of the
288 * register classes. The minimum is used so we guarantee that
289 * this number of entries is available regardless of which class
290 * of registers is requested.
291 */
292 unsigned numFreeEntries() const
293 {
294 return std::min(intMap.numFreeEntries(), floatMap.numFreeEntries());
295 }
296
297 /**
298 * Return whether there are enough registers to serve the request.
299 */
300 bool canRename(uint32_t intRegs, uint32_t floatRegs, uint32_t ccRegs) const
301 {
302 return intRegs <= intMap.numFreeEntries() &&
303 floatRegs <= floatMap.numFreeEntries() &&
304 ccRegs <= ccMap.numFreeEntries();
305 }
306
307};
308
309#endif //__CPU_O3_RENAME_MAP_HH__