1/*
2 * Copyright (c) 2004-2006 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 * Authors: Kevin Lim
29 */
30
31#include "cpu/o3/decode.hh"
32
33template<class Impl>
34DefaultDecode<Impl>::DefaultDecode(Params *params)
35 : renameToDecodeDelay(params->renameToDecodeDelay),
36 iewToDecodeDelay(params->iewToDecodeDelay),
37 commitToDecodeDelay(params->commitToDecodeDelay),
38 fetchToDecodeDelay(params->fetchToDecodeDelay),
39 decodeWidth(params->decodeWidth),
40 numThreads(params->numberOfThreads)
41{
42 _status = Inactive;
43
44 // Setup status, make sure stall signals are clear.
45 for (int i = 0; i < numThreads; ++i) {
46 decodeStatus[i] = Idle;
47
48 stalls[i].rename = false;
49 stalls[i].iew = false;
50 stalls[i].commit = false;
51
52 squashAfterDelaySlot[i] = false;
53 }
54
55 // @todo: Make into a parameter
56 skidBufferMax = (fetchToDecodeDelay * params->fetchWidth) + decodeWidth;
57}
58
59template <class Impl>
60std::string
61DefaultDecode<Impl>::name() const
62{
63 return cpu->name() + ".decode";
64}
65
66template <class Impl>
67void
68DefaultDecode<Impl>::regStats()
69{
70 decodeIdleCycles
71 .name(name() + ".DECODE:IdleCycles")
72 .desc("Number of cycles decode is idle")
73 .prereq(decodeIdleCycles);
74 decodeBlockedCycles
75 .name(name() + ".DECODE:BlockedCycles")
76 .desc("Number of cycles decode is blocked")
77 .prereq(decodeBlockedCycles);
78 decodeRunCycles
79 .name(name() + ".DECODE:RunCycles")
80 .desc("Number of cycles decode is running")
81 .prereq(decodeRunCycles);
82 decodeUnblockCycles
83 .name(name() + ".DECODE:UnblockCycles")
84 .desc("Number of cycles decode is unblocking")
85 .prereq(decodeUnblockCycles);
86 decodeSquashCycles
87 .name(name() + ".DECODE:SquashCycles")
88 .desc("Number of cycles decode is squashing")
89 .prereq(decodeSquashCycles);
90 decodeBranchResolved
91 .name(name() + ".DECODE:BranchResolved")
92 .desc("Number of times decode resolved a branch")
93 .prereq(decodeBranchResolved);
94 decodeBranchMispred
95 .name(name() + ".DECODE:BranchMispred")
96 .desc("Number of times decode detected a branch misprediction")
97 .prereq(decodeBranchMispred);
98 decodeControlMispred
99 .name(name() + ".DECODE:ControlMispred")
100 .desc("Number of times decode detected an instruction incorrectly"
101 " predicted as a control")
102 .prereq(decodeControlMispred);
103 decodeDecodedInsts
104 .name(name() + ".DECODE:DecodedInsts")
105 .desc("Number of instructions handled by decode")
106 .prereq(decodeDecodedInsts);
107 decodeSquashedInsts
108 .name(name() + ".DECODE:SquashedInsts")
109 .desc("Number of squashed instructions handled by decode")
110 .prereq(decodeSquashedInsts);
111}
112
113template<class Impl>
114void
115DefaultDecode<Impl>::setCPU(O3CPU *cpu_ptr)
116{
117 DPRINTF(Decode, "Setting CPU pointer.\n");
118 cpu = cpu_ptr;
119}
120
121template<class Impl>
122void
123DefaultDecode<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
124{
125 DPRINTF(Decode, "Setting time buffer pointer.\n");
126 timeBuffer = tb_ptr;
127
128 // Setup wire to write information back to fetch.
129 toFetch = timeBuffer->getWire(0);
130
131 // Create wires to get information from proper places in time buffer.
132 fromRename = timeBuffer->getWire(-renameToDecodeDelay);
133 fromIEW = timeBuffer->getWire(-iewToDecodeDelay);
134 fromCommit = timeBuffer->getWire(-commitToDecodeDelay);
135}
136
137template<class Impl>
138void
139DefaultDecode<Impl>::setDecodeQueue(TimeBuffer<DecodeStruct> *dq_ptr)
140{
141 DPRINTF(Decode, "Setting decode queue pointer.\n");
142 decodeQueue = dq_ptr;
143
144 // Setup wire to write information to proper place in decode queue.
145 toRename = decodeQueue->getWire(0);
146}
147
148template<class Impl>
149void
150DefaultDecode<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr)
151{
152 DPRINTF(Decode, "Setting fetch queue pointer.\n");
153 fetchQueue = fq_ptr;
154
155 // Setup wire to read information from fetch queue.
156 fromFetch = fetchQueue->getWire(-fetchToDecodeDelay);
157}
158
159template<class Impl>
160void
161DefaultDecode<Impl>::setActiveThreads(std::list<unsigned> *at_ptr)
162{
163 DPRINTF(Decode, "Setting active threads list pointer.\n");
164 activeThreads = at_ptr;
165}
166
167template <class Impl>
168bool
169DefaultDecode<Impl>::drain()
170{
171 // Decode is done draining at any time.
172 cpu->signalDrained();
173 return true;
174}
175
176template <class Impl>
177void
178DefaultDecode<Impl>::takeOverFrom()
179{
180 _status = Inactive;
181
182 // Be sure to reset state and clear out any old instructions.
183 for (int i = 0; i < numThreads; ++i) {
184 decodeStatus[i] = Idle;
185
186 stalls[i].rename = false;
187 stalls[i].iew = false;
188 stalls[i].commit = false;
189 while (!insts[i].empty())
190 insts[i].pop();
191 while (!skidBuffer[i].empty())
192 skidBuffer[i].pop();
193 branchCount[i] = 0;
194 }
195 wroteToTimeBuffer = false;
196}
197
198template<class Impl>
199bool
200DefaultDecode<Impl>::checkStall(unsigned tid) const
201{
202 bool ret_val = false;
203
204 if (stalls[tid].rename) {
205 DPRINTF(Decode,"[tid:%i]: Stall fom Rename stage detected.\n", tid);
206 ret_val = true;
207 } else if (stalls[tid].iew) {
208 DPRINTF(Decode,"[tid:%i]: Stall fom IEW stage detected.\n", tid);
209 ret_val = true;
210 } else if (stalls[tid].commit) {
211 DPRINTF(Decode,"[tid:%i]: Stall fom Commit stage detected.\n", tid);
212 ret_val = true;
213 }
214
215 return ret_val;
216}
217
218template<class Impl>
219inline bool
220DefaultDecode<Impl>::fetchInstsValid()
221{
222 return fromFetch->size > 0;
223}
224
225template<class Impl>
226bool
227DefaultDecode<Impl>::block(unsigned tid)
228{
229 DPRINTF(Decode, "[tid:%u]: Blocking.\n", tid);
230
231 // Add the current inputs to the skid buffer so they can be
232 // reprocessed when this stage unblocks.
233 skidInsert(tid);
234
235 // If the decode status is blocked or unblocking then decode has not yet
236 // signalled fetch to unblock. In that case, there is no need to tell
237 // fetch to block.
238 if (decodeStatus[tid] != Blocked) {
239 // Set the status to Blocked.
240 decodeStatus[tid] = Blocked;
241
242 if (decodeStatus[tid] != Unblocking) {
243 toFetch->decodeBlock[tid] = true;
244 wroteToTimeBuffer = true;
245 }
246
247 return true;
248 }
249
250 return false;
251}
252
253template<class Impl>
254bool
255DefaultDecode<Impl>::unblock(unsigned tid)
256{
257 // Decode is done unblocking only if the skid buffer is empty.
258 if (skidBuffer[tid].empty()) {
259 DPRINTF(Decode, "[tid:%u]: Done unblocking.\n", tid);
260 toFetch->decodeUnblock[tid] = true;
261 wroteToTimeBuffer = true;
262
263 decodeStatus[tid] = Running;
264 return true;
265 }
266
267 DPRINTF(Decode, "[tid:%u]: Currently unblocking.\n", tid);
268
269 return false;
270}
271
272template<class Impl>
273void
274DefaultDecode<Impl>::squash(DynInstPtr &inst, unsigned tid)
275{
276 DPRINTF(Decode, "[tid:%i]: Squashing due to incorrect branch prediction "
277 "detected at decode.\n", tid);
278
279 // Send back mispredict information.
280 toFetch->decodeInfo[tid].branchMispredict = true;
281 toFetch->decodeInfo[tid].predIncorrect = true;
282 toFetch->decodeInfo[tid].doneSeqNum = inst->seqNum;
283 toFetch->decodeInfo[tid].squash = true;
284 toFetch->decodeInfo[tid].nextPC = inst->branchTarget();
285#if ISA_HAS_DELAY_SLOT
286 toFetch->decodeInfo[tid].branchTaken = inst->readNextNPC() !=
287 (inst->readNextPC() + sizeof(TheISA::MachInst));
288
289 toFetch->decodeInfo[tid].bdelayDoneSeqNum = bdelayDoneSeqNum[tid];
290 squashAfterDelaySlot[tid] = false;
291
292 InstSeqNum squash_seq_num = bdelayDoneSeqNum[tid];
293#else
294 toFetch->decodeInfo[tid].branchTaken =
295 inst->readNextPC() != (inst->readPC() + sizeof(TheISA::MachInst));
296
297 InstSeqNum squash_seq_num = inst->seqNum;
298#endif
299
300 // Might have to tell fetch to unblock.
301 if (decodeStatus[tid] == Blocked ||
302 decodeStatus[tid] == Unblocking) {
303 toFetch->decodeUnblock[tid] = 1;
304 }
305
306 // Set status to squashing.
307 decodeStatus[tid] = Squashing;
308
309 for (int i=0; i<fromFetch->size; i++) {
310 if (fromFetch->insts[i]->threadNumber == tid &&
311 fromFetch->insts[i]->seqNum > squash_seq_num) {
312 fromFetch->insts[i]->setSquashed();
313 }
314 }
315
316 // Clear the instruction list and skid buffer in case they have any
317 // insts in them.
318 while (!insts[tid].empty()) {
319
320#if ISA_HAS_DELAY_SLOT
321 if (insts[tid].front()->seqNum <= squash_seq_num) {
322 DPRINTF(Decode, "[tid:%i]: Cannot remove incoming decode "
323 "instructions before delay slot [sn:%i]. %i insts"
324 "left in decode.\n", tid, squash_seq_num,
325 insts[tid].size());
326 break;
327 }
328#endif
329 insts[tid].pop();
330 }
331
332 while (!skidBuffer[tid].empty()) {
333
334#if ISA_HAS_DELAY_SLOT
335 if (skidBuffer[tid].front()->seqNum <= squash_seq_num) {
336 DPRINTF(Decode, "[tid:%i]: Cannot remove skidBuffer "
337 "instructions before delay slot [sn:%i]. %i insts"
338 "left in decode.\n", tid, squash_seq_num,
339 insts[tid].size());
340 break;
341 }
342#endif
343 skidBuffer[tid].pop();
344 }
345
346 // Squash instructions up until this one
347 cpu->removeInstsUntil(squash_seq_num, tid);
348}
349
350template<class Impl>
351unsigned
352DefaultDecode<Impl>::squash(unsigned tid)
353{
354 DPRINTF(Decode, "[tid:%i]: Squashing.\n",tid);
355
356 if (decodeStatus[tid] == Blocked ||
357 decodeStatus[tid] == Unblocking) {
358#if !FULL_SYSTEM
359 // In syscall emulation, we can have both a block and a squash due
360 // to a syscall in the same cycle. This would cause both signals to
361 // be high. This shouldn't happen in full system.
362 // @todo: Determine if this still happens.
363 if (toFetch->decodeBlock[tid]) {
364 toFetch->decodeBlock[tid] = 0;
365 } else {
366 toFetch->decodeUnblock[tid] = 1;
367 }
368#else
369 toFetch->decodeUnblock[tid] = 1;
370#endif
371 }
372
373 // Set status to squashing.
374 decodeStatus[tid] = Squashing;
375
376 // Go through incoming instructions from fetch and squash them.
377 unsigned squash_count = 0;
378
379 for (int i=0; i<fromFetch->size; i++) {
380 if (fromFetch->insts[i]->threadNumber == tid) {
381 fromFetch->insts[i]->setSquashed();
382 squash_count++;
383 }
384 }
385
386 // Clear the instruction list and skid buffer in case they have any
387 // insts in them.
388 while (!insts[tid].empty()) {
389 insts[tid].pop();
390 }
391
392 while (!skidBuffer[tid].empty()) {
393 skidBuffer[tid].pop();
394 }
395
396 return squash_count;
397}
398
399template<class Impl>
400void
401DefaultDecode<Impl>::skidInsert(unsigned tid)
402{
403 DynInstPtr inst = NULL;
404
405 while (!insts[tid].empty()) {
406 inst = insts[tid].front();
407
408 insts[tid].pop();
409
410 assert(tid == inst->threadNumber);
411
412 DPRINTF(Decode,"Inserting [sn:%lli] PC:%#x into decode skidBuffer %i\n",
413 inst->seqNum, inst->readPC(), inst->threadNumber);
414
415 skidBuffer[tid].push(inst);
416 }
417
418 // @todo: Eventually need to enforce this by not letting a thread
419 // fetch past its skidbuffer
420 assert(skidBuffer[tid].size() <= skidBufferMax);
421}
422
423template<class Impl>
424bool
425DefaultDecode<Impl>::skidsEmpty()
426{
| 1/*
2 * Copyright (c) 2004-2006 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 * Authors: Kevin Lim
29 */
30
31#include "cpu/o3/decode.hh"
32
33template<class Impl>
34DefaultDecode<Impl>::DefaultDecode(Params *params)
35 : renameToDecodeDelay(params->renameToDecodeDelay),
36 iewToDecodeDelay(params->iewToDecodeDelay),
37 commitToDecodeDelay(params->commitToDecodeDelay),
38 fetchToDecodeDelay(params->fetchToDecodeDelay),
39 decodeWidth(params->decodeWidth),
40 numThreads(params->numberOfThreads)
41{
42 _status = Inactive;
43
44 // Setup status, make sure stall signals are clear.
45 for (int i = 0; i < numThreads; ++i) {
46 decodeStatus[i] = Idle;
47
48 stalls[i].rename = false;
49 stalls[i].iew = false;
50 stalls[i].commit = false;
51
52 squashAfterDelaySlot[i] = false;
53 }
54
55 // @todo: Make into a parameter
56 skidBufferMax = (fetchToDecodeDelay * params->fetchWidth) + decodeWidth;
57}
58
59template <class Impl>
60std::string
61DefaultDecode<Impl>::name() const
62{
63 return cpu->name() + ".decode";
64}
65
66template <class Impl>
67void
68DefaultDecode<Impl>::regStats()
69{
70 decodeIdleCycles
71 .name(name() + ".DECODE:IdleCycles")
72 .desc("Number of cycles decode is idle")
73 .prereq(decodeIdleCycles);
74 decodeBlockedCycles
75 .name(name() + ".DECODE:BlockedCycles")
76 .desc("Number of cycles decode is blocked")
77 .prereq(decodeBlockedCycles);
78 decodeRunCycles
79 .name(name() + ".DECODE:RunCycles")
80 .desc("Number of cycles decode is running")
81 .prereq(decodeRunCycles);
82 decodeUnblockCycles
83 .name(name() + ".DECODE:UnblockCycles")
84 .desc("Number of cycles decode is unblocking")
85 .prereq(decodeUnblockCycles);
86 decodeSquashCycles
87 .name(name() + ".DECODE:SquashCycles")
88 .desc("Number of cycles decode is squashing")
89 .prereq(decodeSquashCycles);
90 decodeBranchResolved
91 .name(name() + ".DECODE:BranchResolved")
92 .desc("Number of times decode resolved a branch")
93 .prereq(decodeBranchResolved);
94 decodeBranchMispred
95 .name(name() + ".DECODE:BranchMispred")
96 .desc("Number of times decode detected a branch misprediction")
97 .prereq(decodeBranchMispred);
98 decodeControlMispred
99 .name(name() + ".DECODE:ControlMispred")
100 .desc("Number of times decode detected an instruction incorrectly"
101 " predicted as a control")
102 .prereq(decodeControlMispred);
103 decodeDecodedInsts
104 .name(name() + ".DECODE:DecodedInsts")
105 .desc("Number of instructions handled by decode")
106 .prereq(decodeDecodedInsts);
107 decodeSquashedInsts
108 .name(name() + ".DECODE:SquashedInsts")
109 .desc("Number of squashed instructions handled by decode")
110 .prereq(decodeSquashedInsts);
111}
112
113template<class Impl>
114void
115DefaultDecode<Impl>::setCPU(O3CPU *cpu_ptr)
116{
117 DPRINTF(Decode, "Setting CPU pointer.\n");
118 cpu = cpu_ptr;
119}
120
121template<class Impl>
122void
123DefaultDecode<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
124{
125 DPRINTF(Decode, "Setting time buffer pointer.\n");
126 timeBuffer = tb_ptr;
127
128 // Setup wire to write information back to fetch.
129 toFetch = timeBuffer->getWire(0);
130
131 // Create wires to get information from proper places in time buffer.
132 fromRename = timeBuffer->getWire(-renameToDecodeDelay);
133 fromIEW = timeBuffer->getWire(-iewToDecodeDelay);
134 fromCommit = timeBuffer->getWire(-commitToDecodeDelay);
135}
136
137template<class Impl>
138void
139DefaultDecode<Impl>::setDecodeQueue(TimeBuffer<DecodeStruct> *dq_ptr)
140{
141 DPRINTF(Decode, "Setting decode queue pointer.\n");
142 decodeQueue = dq_ptr;
143
144 // Setup wire to write information to proper place in decode queue.
145 toRename = decodeQueue->getWire(0);
146}
147
148template<class Impl>
149void
150DefaultDecode<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr)
151{
152 DPRINTF(Decode, "Setting fetch queue pointer.\n");
153 fetchQueue = fq_ptr;
154
155 // Setup wire to read information from fetch queue.
156 fromFetch = fetchQueue->getWire(-fetchToDecodeDelay);
157}
158
159template<class Impl>
160void
161DefaultDecode<Impl>::setActiveThreads(std::list<unsigned> *at_ptr)
162{
163 DPRINTF(Decode, "Setting active threads list pointer.\n");
164 activeThreads = at_ptr;
165}
166
167template <class Impl>
168bool
169DefaultDecode<Impl>::drain()
170{
171 // Decode is done draining at any time.
172 cpu->signalDrained();
173 return true;
174}
175
176template <class Impl>
177void
178DefaultDecode<Impl>::takeOverFrom()
179{
180 _status = Inactive;
181
182 // Be sure to reset state and clear out any old instructions.
183 for (int i = 0; i < numThreads; ++i) {
184 decodeStatus[i] = Idle;
185
186 stalls[i].rename = false;
187 stalls[i].iew = false;
188 stalls[i].commit = false;
189 while (!insts[i].empty())
190 insts[i].pop();
191 while (!skidBuffer[i].empty())
192 skidBuffer[i].pop();
193 branchCount[i] = 0;
194 }
195 wroteToTimeBuffer = false;
196}
197
198template<class Impl>
199bool
200DefaultDecode<Impl>::checkStall(unsigned tid) const
201{
202 bool ret_val = false;
203
204 if (stalls[tid].rename) {
205 DPRINTF(Decode,"[tid:%i]: Stall fom Rename stage detected.\n", tid);
206 ret_val = true;
207 } else if (stalls[tid].iew) {
208 DPRINTF(Decode,"[tid:%i]: Stall fom IEW stage detected.\n", tid);
209 ret_val = true;
210 } else if (stalls[tid].commit) {
211 DPRINTF(Decode,"[tid:%i]: Stall fom Commit stage detected.\n", tid);
212 ret_val = true;
213 }
214
215 return ret_val;
216}
217
218template<class Impl>
219inline bool
220DefaultDecode<Impl>::fetchInstsValid()
221{
222 return fromFetch->size > 0;
223}
224
225template<class Impl>
226bool
227DefaultDecode<Impl>::block(unsigned tid)
228{
229 DPRINTF(Decode, "[tid:%u]: Blocking.\n", tid);
230
231 // Add the current inputs to the skid buffer so they can be
232 // reprocessed when this stage unblocks.
233 skidInsert(tid);
234
235 // If the decode status is blocked or unblocking then decode has not yet
236 // signalled fetch to unblock. In that case, there is no need to tell
237 // fetch to block.
238 if (decodeStatus[tid] != Blocked) {
239 // Set the status to Blocked.
240 decodeStatus[tid] = Blocked;
241
242 if (decodeStatus[tid] != Unblocking) {
243 toFetch->decodeBlock[tid] = true;
244 wroteToTimeBuffer = true;
245 }
246
247 return true;
248 }
249
250 return false;
251}
252
253template<class Impl>
254bool
255DefaultDecode<Impl>::unblock(unsigned tid)
256{
257 // Decode is done unblocking only if the skid buffer is empty.
258 if (skidBuffer[tid].empty()) {
259 DPRINTF(Decode, "[tid:%u]: Done unblocking.\n", tid);
260 toFetch->decodeUnblock[tid] = true;
261 wroteToTimeBuffer = true;
262
263 decodeStatus[tid] = Running;
264 return true;
265 }
266
267 DPRINTF(Decode, "[tid:%u]: Currently unblocking.\n", tid);
268
269 return false;
270}
271
272template<class Impl>
273void
274DefaultDecode<Impl>::squash(DynInstPtr &inst, unsigned tid)
275{
276 DPRINTF(Decode, "[tid:%i]: Squashing due to incorrect branch prediction "
277 "detected at decode.\n", tid);
278
279 // Send back mispredict information.
280 toFetch->decodeInfo[tid].branchMispredict = true;
281 toFetch->decodeInfo[tid].predIncorrect = true;
282 toFetch->decodeInfo[tid].doneSeqNum = inst->seqNum;
283 toFetch->decodeInfo[tid].squash = true;
284 toFetch->decodeInfo[tid].nextPC = inst->branchTarget();
285#if ISA_HAS_DELAY_SLOT
286 toFetch->decodeInfo[tid].branchTaken = inst->readNextNPC() !=
287 (inst->readNextPC() + sizeof(TheISA::MachInst));
288
289 toFetch->decodeInfo[tid].bdelayDoneSeqNum = bdelayDoneSeqNum[tid];
290 squashAfterDelaySlot[tid] = false;
291
292 InstSeqNum squash_seq_num = bdelayDoneSeqNum[tid];
293#else
294 toFetch->decodeInfo[tid].branchTaken =
295 inst->readNextPC() != (inst->readPC() + sizeof(TheISA::MachInst));
296
297 InstSeqNum squash_seq_num = inst->seqNum;
298#endif
299
300 // Might have to tell fetch to unblock.
301 if (decodeStatus[tid] == Blocked ||
302 decodeStatus[tid] == Unblocking) {
303 toFetch->decodeUnblock[tid] = 1;
304 }
305
306 // Set status to squashing.
307 decodeStatus[tid] = Squashing;
308
309 for (int i=0; i<fromFetch->size; i++) {
310 if (fromFetch->insts[i]->threadNumber == tid &&
311 fromFetch->insts[i]->seqNum > squash_seq_num) {
312 fromFetch->insts[i]->setSquashed();
313 }
314 }
315
316 // Clear the instruction list and skid buffer in case they have any
317 // insts in them.
318 while (!insts[tid].empty()) {
319
320#if ISA_HAS_DELAY_SLOT
321 if (insts[tid].front()->seqNum <= squash_seq_num) {
322 DPRINTF(Decode, "[tid:%i]: Cannot remove incoming decode "
323 "instructions before delay slot [sn:%i]. %i insts"
324 "left in decode.\n", tid, squash_seq_num,
325 insts[tid].size());
326 break;
327 }
328#endif
329 insts[tid].pop();
330 }
331
332 while (!skidBuffer[tid].empty()) {
333
334#if ISA_HAS_DELAY_SLOT
335 if (skidBuffer[tid].front()->seqNum <= squash_seq_num) {
336 DPRINTF(Decode, "[tid:%i]: Cannot remove skidBuffer "
337 "instructions before delay slot [sn:%i]. %i insts"
338 "left in decode.\n", tid, squash_seq_num,
339 insts[tid].size());
340 break;
341 }
342#endif
343 skidBuffer[tid].pop();
344 }
345
346 // Squash instructions up until this one
347 cpu->removeInstsUntil(squash_seq_num, tid);
348}
349
350template<class Impl>
351unsigned
352DefaultDecode<Impl>::squash(unsigned tid)
353{
354 DPRINTF(Decode, "[tid:%i]: Squashing.\n",tid);
355
356 if (decodeStatus[tid] == Blocked ||
357 decodeStatus[tid] == Unblocking) {
358#if !FULL_SYSTEM
359 // In syscall emulation, we can have both a block and a squash due
360 // to a syscall in the same cycle. This would cause both signals to
361 // be high. This shouldn't happen in full system.
362 // @todo: Determine if this still happens.
363 if (toFetch->decodeBlock[tid]) {
364 toFetch->decodeBlock[tid] = 0;
365 } else {
366 toFetch->decodeUnblock[tid] = 1;
367 }
368#else
369 toFetch->decodeUnblock[tid] = 1;
370#endif
371 }
372
373 // Set status to squashing.
374 decodeStatus[tid] = Squashing;
375
376 // Go through incoming instructions from fetch and squash them.
377 unsigned squash_count = 0;
378
379 for (int i=0; i<fromFetch->size; i++) {
380 if (fromFetch->insts[i]->threadNumber == tid) {
381 fromFetch->insts[i]->setSquashed();
382 squash_count++;
383 }
384 }
385
386 // Clear the instruction list and skid buffer in case they have any
387 // insts in them.
388 while (!insts[tid].empty()) {
389 insts[tid].pop();
390 }
391
392 while (!skidBuffer[tid].empty()) {
393 skidBuffer[tid].pop();
394 }
395
396 return squash_count;
397}
398
399template<class Impl>
400void
401DefaultDecode<Impl>::skidInsert(unsigned tid)
402{
403 DynInstPtr inst = NULL;
404
405 while (!insts[tid].empty()) {
406 inst = insts[tid].front();
407
408 insts[tid].pop();
409
410 assert(tid == inst->threadNumber);
411
412 DPRINTF(Decode,"Inserting [sn:%lli] PC:%#x into decode skidBuffer %i\n",
413 inst->seqNum, inst->readPC(), inst->threadNumber);
414
415 skidBuffer[tid].push(inst);
416 }
417
418 // @todo: Eventually need to enforce this by not letting a thread
419 // fetch past its skidbuffer
420 assert(skidBuffer[tid].size() <= skidBufferMax);
421}
422
423template<class Impl>
424bool
425DefaultDecode<Impl>::skidsEmpty()
426{
|
427 std::list<unsigned>::iterator threads = (*activeThreads).begin();
| 427 std::list<unsigned>::iterator threads = activeThreads->begin();
428 std::list<unsigned>::iterator end = activeThreads->end();
|
428
| 429
|
429 while (threads != (*activeThreads).end()) {
430 if (!skidBuffer[*threads++].empty())
| 430 while (threads != end) {
431 unsigned tid = *threads++;
432 if (!skidBuffer[tid].empty())
|
431 return false;
432 }
433
434 return true;
435}
436
437template<class Impl>
438void
439DefaultDecode<Impl>::updateStatus()
440{
441 bool any_unblocking = false;
442
| 433 return false;
434 }
435
436 return true;
437}
438
439template<class Impl>
440void
441DefaultDecode<Impl>::updateStatus()
442{
443 bool any_unblocking = false;
444
|
443 std::list<unsigned>::iterator threads = (*activeThreads).begin();
| 445 std::list<unsigned>::iterator threads = activeThreads->begin();
446 std::list<unsigned>::iterator end = activeThreads->end();
|
444
| 447
|
445 threads = (*activeThreads).begin();
446
447 while (threads != (*activeThreads).end()) {
| 448 while (threads != end) {
|
448 unsigned tid = *threads++;
449
450 if (decodeStatus[tid] == Unblocking) {
451 any_unblocking = true;
452 break;
453 }
454 }
455
456 // Decode will have activity if it's unblocking.
457 if (any_unblocking) {
458 if (_status == Inactive) {
459 _status = Active;
460
461 DPRINTF(Activity, "Activating stage.\n");
462
463 cpu->activateStage(O3CPU::DecodeIdx);
464 }
465 } else {
466 // If it's not unblocking, then decode will not have any internal
467 // activity. Switch it to inactive.
468 if (_status == Active) {
469 _status = Inactive;
470 DPRINTF(Activity, "Deactivating stage.\n");
471
472 cpu->deactivateStage(O3CPU::DecodeIdx);
473 }
474 }
475}
476
477template <class Impl>
478void
479DefaultDecode<Impl>::sortInsts()
480{
481 int insts_from_fetch = fromFetch->size;
482#ifdef DEBUG
483 for (int i=0; i < numThreads; i++)
484 assert(insts[i].empty());
485#endif
486 for (int i = 0; i < insts_from_fetch; ++i) {
487 insts[fromFetch->insts[i]->threadNumber].push(fromFetch->insts[i]);
488 }
489}
490
491template<class Impl>
492void
493DefaultDecode<Impl>::readStallSignals(unsigned tid)
494{
495 if (fromRename->renameBlock[tid]) {
496 stalls[tid].rename = true;
497 }
498
499 if (fromRename->renameUnblock[tid]) {
500 assert(stalls[tid].rename);
501 stalls[tid].rename = false;
502 }
503
504 if (fromIEW->iewBlock[tid]) {
505 stalls[tid].iew = true;
506 }
507
508 if (fromIEW->iewUnblock[tid]) {
509 assert(stalls[tid].iew);
510 stalls[tid].iew = false;
511 }
512
513 if (fromCommit->commitBlock[tid]) {
514 stalls[tid].commit = true;
515 }
516
517 if (fromCommit->commitUnblock[tid]) {
518 assert(stalls[tid].commit);
519 stalls[tid].commit = false;
520 }
521}
522
523template <class Impl>
524bool
525DefaultDecode<Impl>::checkSignalsAndUpdate(unsigned tid)
526{
527 // Check if there's a squash signal, squash if there is.
528 // Check stall signals, block if necessary.
529 // If status was blocked
530 // Check if stall conditions have passed
531 // if so then go to unblocking
532 // If status was Squashing
533 // check if squashing is not high. Switch to running this cycle.
534
535 // Update the per thread stall statuses.
536 readStallSignals(tid);
537
538 // Check squash signals from commit.
539 if (fromCommit->commitInfo[tid].squash) {
540
541 DPRINTF(Decode, "[tid:%u]: Squashing instructions due to squash "
542 "from commit.\n", tid);
543
544 squash(tid);
545
546 return true;
547 }
548
549 // Check ROB squash signals from commit.
550 if (fromCommit->commitInfo[tid].robSquashing) {
551 DPRINTF(Decode, "[tid:%u]: ROB is still squashing.\n", tid);
552
553 // Continue to squash.
554 decodeStatus[tid] = Squashing;
555
556 return true;
557 }
558
559 if (checkStall(tid)) {
560 return block(tid);
561 }
562
563 if (decodeStatus[tid] == Blocked) {
564 DPRINTF(Decode, "[tid:%u]: Done blocking, switching to unblocking.\n",
565 tid);
566
567 decodeStatus[tid] = Unblocking;
568
569 unblock(tid);
570
571 return true;
572 }
573
574 if (decodeStatus[tid] == Squashing) {
575 // Switch status to running if decode isn't being told to block or
576 // squash this cycle.
577 DPRINTF(Decode, "[tid:%u]: Done squashing, switching to running.\n",
578 tid);
579
580 decodeStatus[tid] = Running;
581
582 return false;
583 }
584
585 // If we've reached this point, we have not gotten any signals that
586 // cause decode to change its status. Decode remains the same as before.
587 return false;
588}
589
590template<class Impl>
591void
592DefaultDecode<Impl>::tick()
593{
594 wroteToTimeBuffer = false;
595
596 bool status_change = false;
597
598 toRenameIndex = 0;
599
| 449 unsigned tid = *threads++;
450
451 if (decodeStatus[tid] == Unblocking) {
452 any_unblocking = true;
453 break;
454 }
455 }
456
457 // Decode will have activity if it's unblocking.
458 if (any_unblocking) {
459 if (_status == Inactive) {
460 _status = Active;
461
462 DPRINTF(Activity, "Activating stage.\n");
463
464 cpu->activateStage(O3CPU::DecodeIdx);
465 }
466 } else {
467 // If it's not unblocking, then decode will not have any internal
468 // activity. Switch it to inactive.
469 if (_status == Active) {
470 _status = Inactive;
471 DPRINTF(Activity, "Deactivating stage.\n");
472
473 cpu->deactivateStage(O3CPU::DecodeIdx);
474 }
475 }
476}
477
478template <class Impl>
479void
480DefaultDecode<Impl>::sortInsts()
481{
482 int insts_from_fetch = fromFetch->size;
483#ifdef DEBUG
484 for (int i=0; i < numThreads; i++)
485 assert(insts[i].empty());
486#endif
487 for (int i = 0; i < insts_from_fetch; ++i) {
488 insts[fromFetch->insts[i]->threadNumber].push(fromFetch->insts[i]);
489 }
490}
491
492template<class Impl>
493void
494DefaultDecode<Impl>::readStallSignals(unsigned tid)
495{
496 if (fromRename->renameBlock[tid]) {
497 stalls[tid].rename = true;
498 }
499
500 if (fromRename->renameUnblock[tid]) {
501 assert(stalls[tid].rename);
502 stalls[tid].rename = false;
503 }
504
505 if (fromIEW->iewBlock[tid]) {
506 stalls[tid].iew = true;
507 }
508
509 if (fromIEW->iewUnblock[tid]) {
510 assert(stalls[tid].iew);
511 stalls[tid].iew = false;
512 }
513
514 if (fromCommit->commitBlock[tid]) {
515 stalls[tid].commit = true;
516 }
517
518 if (fromCommit->commitUnblock[tid]) {
519 assert(stalls[tid].commit);
520 stalls[tid].commit = false;
521 }
522}
523
524template <class Impl>
525bool
526DefaultDecode<Impl>::checkSignalsAndUpdate(unsigned tid)
527{
528 // Check if there's a squash signal, squash if there is.
529 // Check stall signals, block if necessary.
530 // If status was blocked
531 // Check if stall conditions have passed
532 // if so then go to unblocking
533 // If status was Squashing
534 // check if squashing is not high. Switch to running this cycle.
535
536 // Update the per thread stall statuses.
537 readStallSignals(tid);
538
539 // Check squash signals from commit.
540 if (fromCommit->commitInfo[tid].squash) {
541
542 DPRINTF(Decode, "[tid:%u]: Squashing instructions due to squash "
543 "from commit.\n", tid);
544
545 squash(tid);
546
547 return true;
548 }
549
550 // Check ROB squash signals from commit.
551 if (fromCommit->commitInfo[tid].robSquashing) {
552 DPRINTF(Decode, "[tid:%u]: ROB is still squashing.\n", tid);
553
554 // Continue to squash.
555 decodeStatus[tid] = Squashing;
556
557 return true;
558 }
559
560 if (checkStall(tid)) {
561 return block(tid);
562 }
563
564 if (decodeStatus[tid] == Blocked) {
565 DPRINTF(Decode, "[tid:%u]: Done blocking, switching to unblocking.\n",
566 tid);
567
568 decodeStatus[tid] = Unblocking;
569
570 unblock(tid);
571
572 return true;
573 }
574
575 if (decodeStatus[tid] == Squashing) {
576 // Switch status to running if decode isn't being told to block or
577 // squash this cycle.
578 DPRINTF(Decode, "[tid:%u]: Done squashing, switching to running.\n",
579 tid);
580
581 decodeStatus[tid] = Running;
582
583 return false;
584 }
585
586 // If we've reached this point, we have not gotten any signals that
587 // cause decode to change its status. Decode remains the same as before.
588 return false;
589}
590
591template<class Impl>
592void
593DefaultDecode<Impl>::tick()
594{
595 wroteToTimeBuffer = false;
596
597 bool status_change = false;
598
599 toRenameIndex = 0;
600
|
600 std::list<unsigned>::iterator threads = (*activeThreads).begin();
| 601 std::list<unsigned>::iterator threads = activeThreads->begin();
602 std::list<unsigned>::iterator end = activeThreads->end();
|
601
602 sortInsts();
603
604 //Check stall and squash signals.
| 603
604 sortInsts();
605
606 //Check stall and squash signals.
|
605 while (threads != (*activeThreads).end()) {
606 unsigned tid = *threads++;
| 607 while (threads != end) {
608 unsigned tid = *threads++;
|
607
608 DPRINTF(Decode,"Processing [tid:%i]\n",tid);
609 status_change = checkSignalsAndUpdate(tid) || status_change;
610
611 decode(status_change, tid);
612 }
613
614 if (status_change) {
615 updateStatus();
616 }
617
618 if (wroteToTimeBuffer) {
619 DPRINTF(Activity, "Activity this cycle.\n");
620
621 cpu->activityThisCycle();
622 }
623}
624
625template<class Impl>
626void
627DefaultDecode<Impl>::decode(bool &status_change, unsigned tid)
628{
629 // If status is Running or idle,
630 // call decodeInsts()
631 // If status is Unblocking,
632 // buffer any instructions coming from fetch
633 // continue trying to empty skid buffer
634 // check if stall conditions have passed
635
636 if (decodeStatus[tid] == Blocked) {
637 ++decodeBlockedCycles;
638 } else if (decodeStatus[tid] == Squashing) {
639 ++decodeSquashCycles;
640 }
641
642 // Decode should try to decode as many instructions as its bandwidth
643 // will allow, as long as it is not currently blocked.
644 if (decodeStatus[tid] == Running ||
645 decodeStatus[tid] == Idle) {
646 DPRINTF(Decode, "[tid:%u]: Not blocked, so attempting to run "
647 "stage.\n",tid);
648
649 decodeInsts(tid);
650 } else if (decodeStatus[tid] == Unblocking) {
651 // Make sure that the skid buffer has something in it if the
652 // status is unblocking.
653 assert(!skidsEmpty());
654
655 // If the status was unblocking, then instructions from the skid
656 // buffer were used. Remove those instructions and handle
657 // the rest of unblocking.
658 decodeInsts(tid);
659
660 if (fetchInstsValid()) {
661 // Add the current inputs to the skid buffer so they can be
662 // reprocessed when this stage unblocks.
663 skidInsert(tid);
664 }
665
666 status_change = unblock(tid) || status_change;
667 }
668}
669
670template <class Impl>
671void
672DefaultDecode<Impl>::decodeInsts(unsigned tid)
673{
674 // Instructions can come either from the skid buffer or the list of
675 // instructions coming from fetch, depending on decode's status.
676 int insts_available = decodeStatus[tid] == Unblocking ?
677 skidBuffer[tid].size() : insts[tid].size();
678
679 if (insts_available == 0) {
680 DPRINTF(Decode, "[tid:%u] Nothing to do, breaking out"
681 " early.\n",tid);
682 // Should I change the status to idle?
683 ++decodeIdleCycles;
684 return;
685 } else if (decodeStatus[tid] == Unblocking) {
686 DPRINTF(Decode, "[tid:%u] Unblocking, removing insts from skid "
687 "buffer.\n",tid);
688 ++decodeUnblockCycles;
689 } else if (decodeStatus[tid] == Running) {
690 ++decodeRunCycles;
691 }
692
693 DynInstPtr inst;
694
695 std::queue<DynInstPtr>
696 &insts_to_decode = decodeStatus[tid] == Unblocking ?
697 skidBuffer[tid] : insts[tid];
698
699 DPRINTF(Decode, "[tid:%u]: Sending instruction to rename.\n",tid);
700
701 while (insts_available > 0 && toRenameIndex < decodeWidth) {
702 assert(!insts_to_decode.empty());
703
704 inst = insts_to_decode.front();
705
706 insts_to_decode.pop();
707
708 DPRINTF(Decode, "[tid:%u]: Processing instruction [sn:%lli] with "
709 "PC %#x\n",
710 tid, inst->seqNum, inst->readPC());
711
712 if (inst->isSquashed()) {
713 DPRINTF(Decode, "[tid:%u]: Instruction %i with PC %#x is "
714 "squashed, skipping.\n",
715 tid, inst->seqNum, inst->readPC());
716
717 ++decodeSquashedInsts;
718
719 --insts_available;
720
721 continue;
722 }
723
724 // Also check if instructions have no source registers. Mark
725 // them as ready to issue at any time. Not sure if this check
726 // should exist here or at a later stage; however it doesn't matter
727 // too much for function correctness.
728 if (inst->numSrcRegs() == 0) {
729 inst->setCanIssue();
730 }
731
732 // This current instruction is valid, so add it into the decode
733 // queue. The next instruction may not be valid, so check to
734 // see if branches were predicted correctly.
735 toRename->insts[toRenameIndex] = inst;
736
737 ++(toRename->size);
738 ++toRenameIndex;
739 ++decodeDecodedInsts;
740 --insts_available;
741
742 // Ensure that if it was predicted as a branch, it really is a
743 // branch.
| 609
610 DPRINTF(Decode,"Processing [tid:%i]\n",tid);
611 status_change = checkSignalsAndUpdate(tid) || status_change;
612
613 decode(status_change, tid);
614 }
615
616 if (status_change) {
617 updateStatus();
618 }
619
620 if (wroteToTimeBuffer) {
621 DPRINTF(Activity, "Activity this cycle.\n");
622
623 cpu->activityThisCycle();
624 }
625}
626
627template<class Impl>
628void
629DefaultDecode<Impl>::decode(bool &status_change, unsigned tid)
630{
631 // If status is Running or idle,
632 // call decodeInsts()
633 // If status is Unblocking,
634 // buffer any instructions coming from fetch
635 // continue trying to empty skid buffer
636 // check if stall conditions have passed
637
638 if (decodeStatus[tid] == Blocked) {
639 ++decodeBlockedCycles;
640 } else if (decodeStatus[tid] == Squashing) {
641 ++decodeSquashCycles;
642 }
643
644 // Decode should try to decode as many instructions as its bandwidth
645 // will allow, as long as it is not currently blocked.
646 if (decodeStatus[tid] == Running ||
647 decodeStatus[tid] == Idle) {
648 DPRINTF(Decode, "[tid:%u]: Not blocked, so attempting to run "
649 "stage.\n",tid);
650
651 decodeInsts(tid);
652 } else if (decodeStatus[tid] == Unblocking) {
653 // Make sure that the skid buffer has something in it if the
654 // status is unblocking.
655 assert(!skidsEmpty());
656
657 // If the status was unblocking, then instructions from the skid
658 // buffer were used. Remove those instructions and handle
659 // the rest of unblocking.
660 decodeInsts(tid);
661
662 if (fetchInstsValid()) {
663 // Add the current inputs to the skid buffer so they can be
664 // reprocessed when this stage unblocks.
665 skidInsert(tid);
666 }
667
668 status_change = unblock(tid) || status_change;
669 }
670}
671
672template <class Impl>
673void
674DefaultDecode<Impl>::decodeInsts(unsigned tid)
675{
676 // Instructions can come either from the skid buffer or the list of
677 // instructions coming from fetch, depending on decode's status.
678 int insts_available = decodeStatus[tid] == Unblocking ?
679 skidBuffer[tid].size() : insts[tid].size();
680
681 if (insts_available == 0) {
682 DPRINTF(Decode, "[tid:%u] Nothing to do, breaking out"
683 " early.\n",tid);
684 // Should I change the status to idle?
685 ++decodeIdleCycles;
686 return;
687 } else if (decodeStatus[tid] == Unblocking) {
688 DPRINTF(Decode, "[tid:%u] Unblocking, removing insts from skid "
689 "buffer.\n",tid);
690 ++decodeUnblockCycles;
691 } else if (decodeStatus[tid] == Running) {
692 ++decodeRunCycles;
693 }
694
695 DynInstPtr inst;
696
697 std::queue<DynInstPtr>
698 &insts_to_decode = decodeStatus[tid] == Unblocking ?
699 skidBuffer[tid] : insts[tid];
700
701 DPRINTF(Decode, "[tid:%u]: Sending instruction to rename.\n",tid);
702
703 while (insts_available > 0 && toRenameIndex < decodeWidth) {
704 assert(!insts_to_decode.empty());
705
706 inst = insts_to_decode.front();
707
708 insts_to_decode.pop();
709
710 DPRINTF(Decode, "[tid:%u]: Processing instruction [sn:%lli] with "
711 "PC %#x\n",
712 tid, inst->seqNum, inst->readPC());
713
714 if (inst->isSquashed()) {
715 DPRINTF(Decode, "[tid:%u]: Instruction %i with PC %#x is "
716 "squashed, skipping.\n",
717 tid, inst->seqNum, inst->readPC());
718
719 ++decodeSquashedInsts;
720
721 --insts_available;
722
723 continue;
724 }
725
726 // Also check if instructions have no source registers. Mark
727 // them as ready to issue at any time. Not sure if this check
728 // should exist here or at a later stage; however it doesn't matter
729 // too much for function correctness.
730 if (inst->numSrcRegs() == 0) {
731 inst->setCanIssue();
732 }
733
734 // This current instruction is valid, so add it into the decode
735 // queue. The next instruction may not be valid, so check to
736 // see if branches were predicted correctly.
737 toRename->insts[toRenameIndex] = inst;
738
739 ++(toRename->size);
740 ++toRenameIndex;
741 ++decodeDecodedInsts;
742 --insts_available;
743
744 // Ensure that if it was predicted as a branch, it really is a
745 // branch.
|
744 if (inst->readPredTaken() && !inst->isControl()) {
| 746 if (inst->predTaken() && !inst->isControl()) {
|
745 DPRINTF(Decode, "PredPC : %#x != NextPC: %#x\n",inst->predPC,
746 inst->nextPC + 4);
747
748 panic("Instruction predicted as a branch!");
749
750 ++decodeControlMispred;
751
752 // Might want to set some sort of boolean and just do
753 // a check at the end
754 squash(inst, inst->threadNumber);
755
756 break;
757 }
758
759 // Go ahead and compute any PC-relative branches.
760 if (inst->isDirectCtrl() && inst->isUncondCtrl()) {
761 ++decodeBranchResolved;
762
| 747 DPRINTF(Decode, "PredPC : %#x != NextPC: %#x\n",inst->predPC,
748 inst->nextPC + 4);
749
750 panic("Instruction predicted as a branch!");
751
752 ++decodeControlMispred;
753
754 // Might want to set some sort of boolean and just do
755 // a check at the end
756 squash(inst, inst->threadNumber);
757
758 break;
759 }
760
761 // Go ahead and compute any PC-relative branches.
762 if (inst->isDirectCtrl() && inst->isUncondCtrl()) {
763 ++decodeBranchResolved;
764
|
763 if (inst->branchTarget() != inst->readPredPC()) {
| 765 if (inst->branchTarget() != inst->readPredTarg()) {
|
764 ++decodeBranchMispred;
765
766 // Might want to set some sort of boolean and just do
767 // a check at the end
768#if !ISA_HAS_DELAY_SLOT
769 squash(inst, inst->threadNumber);
| 766 ++decodeBranchMispred;
767
768 // Might want to set some sort of boolean and just do
769 // a check at the end
770#if !ISA_HAS_DELAY_SLOT
771 squash(inst, inst->threadNumber);
|
770 Addr target = inst->branchTarget();
771 inst->setPredTarg(target, target + sizeof(TheISA::MachInst));
| 772 inst->setPredTarg(inst->branchTarget());
|
772 break;
773#else
774 // If mispredicted as taken, then ignore delay slot
775 // instruction... else keep delay slot and squash
776 // after it is sent to rename
| 773 break;
774#else
775 // If mispredicted as taken, then ignore delay slot
776 // instruction... else keep delay slot and squash
777 // after it is sent to rename
|
777 if (inst->readPredTaken() && inst->isCondDelaySlot()) {
| 778 if (inst->predTaken() && inst->isCondDelaySlot()) {
|
778 DPRINTF(Decode, "[tid:%i]: Conditional delay slot inst."
779 "[sn:%i] PC %#x mispredicted as taken.\n", tid,
780 inst->seqNum, inst->PC);
781 bdelayDoneSeqNum[tid] = inst->seqNum;
782 squash(inst, inst->threadNumber);
| 779 DPRINTF(Decode, "[tid:%i]: Conditional delay slot inst."
780 "[sn:%i] PC %#x mispredicted as taken.\n", tid,
781 inst->seqNum, inst->PC);
782 bdelayDoneSeqNum[tid] = inst->seqNum;
783 squash(inst, inst->threadNumber);
|
783 Addr target = inst->branchTarget();
784 inst->setPredTarg(target,
785 target + sizeof(TheISA::MachInst));
| 784 inst->setPredTarg(inst->branchTarget());
|
786 break;
787 } else {
788 DPRINTF(Decode, "[tid:%i]: Misprediction detected at "
789 "[sn:%i] PC %#x, will squash after delay slot "
790 "inst. is sent to Rename\n",
791 tid, inst->seqNum, inst->PC);
792 bdelayDoneSeqNum[tid] = inst->seqNum + 1;
793 squashAfterDelaySlot[tid] = true;
794 squashInst[tid] = inst;
795 continue;
796 }
797#endif
798 }
799 }
800
801 if (squashAfterDelaySlot[tid]) {
802 assert(!inst->isSquashed());
803 squash(squashInst[tid], squashInst[tid]->threadNumber);
| 785 break;
786 } else {
787 DPRINTF(Decode, "[tid:%i]: Misprediction detected at "
788 "[sn:%i] PC %#x, will squash after delay slot "
789 "inst. is sent to Rename\n",
790 tid, inst->seqNum, inst->PC);
791 bdelayDoneSeqNum[tid] = inst->seqNum + 1;
792 squashAfterDelaySlot[tid] = true;
793 squashInst[tid] = inst;
794 continue;
795 }
796#endif
797 }
798 }
799
800 if (squashAfterDelaySlot[tid]) {
801 assert(!inst->isSquashed());
802 squash(squashInst[tid], squashInst[tid]->threadNumber);
|
804 Addr target = squashInst[tid]->branchTarget();
805 squashInst[tid]->setPredTarg(target,
806 target + sizeof(TheISA::MachInst));
| 803 squashInst[tid]->setPredTarg(squashInst[tid]->branchTarget());
|
807 assert(!inst->isSquashed());
808 break;
809 }
810 }
811
812 // If we didn't process all instructions, then we will need to block
813 // and put all those instructions into the skid buffer.
814 if (!insts_to_decode.empty()) {
815 block(tid);
816 }
817
818 // Record that decode has written to the time buffer for activity
819 // tracking.
820 if (toRenameIndex) {
821 wroteToTimeBuffer = true;
822 }
823}
| 804 assert(!inst->isSquashed());
805 break;
806 }
807 }
808
809 // If we didn't process all instructions, then we will need to block
810 // and put all those instructions into the skid buffer.
811 if (!insts_to_decode.empty()) {
812 block(tid);
813 }
814
815 // Record that decode has written to the time buffer for activity
816 // tracking.
817 if (toRenameIndex) {
818 wroteToTimeBuffer = true;
819 }
820}
|