rob.hh revision 2307
1/* 2 * Copyright (c) 2004-2005 The Regents of The University of Michigan 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29#ifndef __CPU_O3_ROB_HH__ 30#define __CPU_O3_ROB_HH__ 31 32#include <string> 33#include <utility> 34#include <vector> 35 36/** 37 * ROB class. The ROB is largely what drives squashing. 38 */ 39template <class Impl> 40class ROB 41{ 42 protected: 43 typedef TheISA::RegIndex RegIndex; 44 public: 45 //Typedefs from the Impl. 46 typedef typename Impl::FullCPU FullCPU; 47 typedef typename Impl::DynInstPtr DynInstPtr; 48 49 typedef std::pair<RegIndex, PhysRegIndex> UnmapInfo; 50 typedef typename std::list<DynInstPtr>::iterator InstIt; 51 52 /** Possible ROB statuses. */ 53 enum Status { 54 Running, 55 Idle, 56 ROBSquashing, 57 DcacheMissStall, 58 DcacheMissComplete 59 }; 60 61 /** SMT ROB Sharing Policy */ 62 enum ROBPolicy{ 63 Dynamic, 64 Partitioned, 65 Threshold 66 }; 67 68 private: 69 /** Per-thread ROB status. */ 70 Status robStatus[Impl::MaxThreads]; 71 72 /** ROB resource sharing policy for SMT mode. */ 73 ROBPolicy robPolicy; 74 75 public: 76 /** ROB constructor. 77 * @param _numEntries Number of entries in ROB. 78 * @param _squashWidth Number of instructions that can be squashed in a 79 * single cycle. 80 * @param _smtROBPolicy ROB Partitioning Scheme for SMT. 81 * @param _smtROBThreshold Max Resources(by %) a thread can have in the ROB. 82 * @param _numThreads The number of active threads. 83 */ 84 ROB(unsigned _numEntries, unsigned _squashWidth, std::string smtROBPolicy, 85 unsigned _smtROBThreshold, unsigned _numThreads); 86 87 std::string name() const; 88 89 /** Function to set the CPU pointer, necessary due to which object the ROB 90 * is created within. 91 * @param cpu_ptr Pointer to the implementation specific full CPU object. 92 */ 93 void setCPU(FullCPU *cpu_ptr); 94 95 /** Sets pointer to the list of active threads. 96 * @param at_ptr Pointer to the list of active threads. 97 */ 98 void setActiveThreads(std::list<unsigned>* at_ptr); 99 100 void switchOut(); 101 102 void takeOverFrom(); 103 104 /** Function to insert an instruction into the ROB. Note that whatever 105 * calls this function must ensure that there is enough space within the 106 * ROB for the new instruction. 107 * @param inst The instruction being inserted into the ROB. 108 */ 109 void insertInst(DynInstPtr &inst); 110 111 /** Returns pointer to the head instruction within the ROB. There is 112 * no guarantee as to the return value if the ROB is empty. 113 * @retval Pointer to the DynInst that is at the head of the ROB. 114 */ 115 DynInstPtr readHeadInst(); 116 117 /** Returns a pointer to the head instruction of a specific thread within 118 * the ROB. 119 * @return Pointer to the DynInst that is at the head of the ROB. 120 */ 121 DynInstPtr readHeadInst(unsigned tid); 122 123 /** Returns pointer to the tail instruction within the ROB. There is 124 * no guarantee as to the return value if the ROB is empty. 125 * @retval Pointer to the DynInst that is at the tail of the ROB. 126 */ 127 DynInstPtr readTailInst(); 128 129 /** Returns a pointer to the tail instruction of a specific thread within 130 * the ROB. 131 * @return Pointer to the DynInst that is at the tail of the ROB. 132 */ 133 DynInstPtr readTailInst(unsigned tid); 134 135 /** Retires the head instruction, removing it from the ROB. */ 136 void retireHead(); 137 138 /** Retires the head instruction of a specific thread, removing it from the 139 * ROB. 140 */ 141 void retireHead(unsigned tid); 142 143 /** Is the oldest instruction across all threads ready. */ 144 bool isHeadReady(); 145 146 /** Is the oldest instruction across a particular thread ready. */ 147 bool isHeadReady(unsigned tid); 148 149 /** Is there any commitable head instruction across all threads ready. */ 150 bool canCommit(); 151 152 /** Re-adjust ROB partitioning. */ 153 void resetEntries(); 154 155 /** Number of entries needed For 'num_threads' amount of threads. */ 156 int entryAmount(int num_threads); 157 158 /** Returns the number of total free entries in the ROB. */ 159 unsigned numFreeEntries(); 160 161 /** Returns the number of free entries in a specific ROB paritition. */ 162 unsigned numFreeEntries(unsigned tid); 163 164 /** Returns the maximum number of entries for a specific thread. */ 165 unsigned getMaxEntries(unsigned tid) 166 { return maxEntries[tid]; } 167 168 /** Returns the number of entries being used by a specific thread. */ 169 unsigned getThreadEntries(unsigned tid) 170 { return threadEntries[tid]; } 171 172 /** Returns if the ROB is full. */ 173 bool isFull() 174 { return numInstsInROB == numEntries; } 175 176 /** Returns if a specific thread's partition is full. */ 177 bool isFull(unsigned tid) 178 { return threadEntries[tid] == numEntries; } 179 180 /** Returns if the ROB is empty. */ 181 bool isEmpty() 182 { return numInstsInROB == 0; } 183 184 /** Returns if a specific thread's partition is empty. */ 185 bool isEmpty(unsigned tid) 186 { return threadEntries[tid] == 0; } 187 188 /** Executes the squash, marking squashed instructions. */ 189 void doSquash(unsigned tid); 190 191 /** Squashes all instructions younger than the given sequence number for 192 * the specific thread. 193 */ 194 void squash(InstSeqNum squash_num, unsigned tid); 195 196 /** Updates the head instruction with the new oldest instruction. */ 197 void updateHead(); 198 199 /** Updates the tail instruction with the new youngest instruction. */ 200 void updateTail(); 201 202 /** Reads the PC of the oldest head instruction. */ 203 uint64_t readHeadPC(); 204 205 /** Reads the PC of the head instruction of a specific thread. */ 206 uint64_t readHeadPC(unsigned tid); 207 208 /** Reads the next PC of the oldest head instruction. */ 209 uint64_t readHeadNextPC(); 210 211 /** Reads the next PC of the head instruction of a specific thread. */ 212 uint64_t readHeadNextPC(unsigned tid); 213 214 /** Reads the sequence number of the oldest head instruction. */ 215 InstSeqNum readHeadSeqNum(); 216 217 /** Reads the sequence number of the head instruction of a specific thread. 218 */ 219 InstSeqNum readHeadSeqNum(unsigned tid); 220 221 /** Reads the PC of the youngest tail instruction. */ 222 uint64_t readTailPC(); 223 224 /** Reads the PC of the tail instruction of a specific thread. */ 225 uint64_t readTailPC(unsigned tid); 226 227 /** Reads the sequence number of the youngest tail instruction. */ 228 InstSeqNum readTailSeqNum(); 229 230 /** Reads the sequence number of tail instruction of a specific thread. */ 231 InstSeqNum readTailSeqNum(unsigned tid); 232 233 /** Checks if the ROB is still in the process of squashing instructions. 234 * @retval Whether or not the ROB is done squashing. 235 */ 236 bool isDoneSquashing(unsigned tid) const 237 { return doneSquashing[tid]; } 238 239 /** Checks if the ROB is still in the process of squashing instructions for 240 * any thread. 241 */ 242 bool isDoneSquashing(); 243 244 /** This is more of a debugging function than anything. Use 245 * numInstsInROB to get the instructions in the ROB unless you are 246 * double checking that variable. 247 */ 248 int countInsts(); 249 250 /** This is more of a debugging function than anything. Use 251 * threadEntries to get the instructions in the ROB unless you are 252 * double checking that variable. 253 */ 254 int countInsts(unsigned tid); 255 256 private: 257 /** Pointer to the CPU. */ 258 FullCPU *cpu; 259 260 /** Active Threads in CPU */ 261 std::list<unsigned>* activeThreads; 262 263 /** Number of instructions in the ROB. */ 264 unsigned numEntries; 265 266 /** Entries Per Thread */ 267 unsigned threadEntries[Impl::MaxThreads]; 268 269 /** Max Insts a Thread Can Have in the ROB */ 270 unsigned maxEntries[Impl::MaxThreads]; 271 272 /** ROB List of Instructions */ 273 std::list<DynInstPtr> instList[Impl::MaxThreads]; 274 275 /** Number of instructions that can be squashed in a single cycle. */ 276 unsigned squashWidth; 277 278 public: 279 /** Iterator pointing to the instruction which is the last instruction 280 * in the ROB. This may at times be invalid (ie when the ROB is empty), 281 * however it should never be incorrect. 282 */ 283 InstIt tail; 284 285 /** Iterator pointing to the instruction which is the first instruction in 286 * in the ROB*/ 287 InstIt head; 288 289 private: 290 /** Iterator used for walking through the list of instructions when 291 * squashing. Used so that there is persistent state between cycles; 292 * when squashing, the instructions are marked as squashed but not 293 * immediately removed, meaning the tail iterator remains the same before 294 * and after a squash. 295 * This will always be set to cpu->instList.end() if it is invalid. 296 */ 297 InstIt squashIt[Impl::MaxThreads]; 298 299 public: 300 /** Number of instructions in the ROB. */ 301 int numInstsInROB; 302 303 DynInstPtr dummyInst; 304 305 private: 306 /** The sequence number of the squashed instruction. */ 307 InstSeqNum squashedSeqNum; 308 309 /** Is the ROB done squashing. */ 310 bool doneSquashing[Impl::MaxThreads]; 311 312 /** Number of active threads. */ 313 unsigned numThreads; 314}; 315 316#endif //__CPU_O3_ROB_HH__ 317