// Setup PC and nextPC with initial state.
for (ThreadID tid = 0; tid < numThreads; tid++) {
pc[tid] = cpu->pcState(tid);
+ fetchOffset[tid] = 0;
+ macroop[tid] = NULL;
}
for (ThreadID tid = 0; tid < numThreads; tid++) {
template <class Impl>
bool
-DefaultFetch<Impl>::fetchCacheLine(Addr fetch_PC, Fault &ret_fault, ThreadID tid)
+DefaultFetch<Impl>::fetchCacheLine(Addr vaddr, Fault &ret_fault, ThreadID tid,
+ Addr pc)
{
Fault fault = NoFault;
DPRINTF(Fetch, "[tid:%i] Can't fetch cache line, switched out\n",
tid);
return false;
- } else if (interruptPending && !(fetch_PC & 0x3)) {
+ } else if (interruptPending && !(pc & 0x3)) {
// Hold off fetch from getting new instructions when:
// Cache is blocked, or
// while an interrupt is pending and we're not in PAL mode, or
return false;
}
- // Align the fetch PC so it's at the start of a cache block.
- Addr block_PC = icacheBlockAlignPC(fetch_PC);
+ // Align the fetch address so it's at the start of a cache block.
+ Addr block_PC = icacheBlockAlignPC(vaddr);
// If we've already got the block, no need to try to fetch it again.
if (cacheDataValid[tid] && block_PC == cacheDataPC[tid]) {
// Build request here.
RequestPtr mem_req =
new Request(tid, block_PC, cacheBlkSize, Request::INST_FETCH,
- fetch_PC, cpu->thread[tid]->contextId(), tid);
+ pc, cpu->thread[tid]->contextId(), tid);
memReq[tid] = mem_req;
tid, newPC);
pc[tid] = newPC;
+ fetchOffset[tid] = 0;
+ macroop[tid] = NULL;
+ predecoder.reset();
// Clear the icache miss if it's outstanding.
if (fetchStatus[tid] == IcacheWaitResponse) {
return false;
}
+template<class Impl>
+typename Impl::DynInstPtr
+DefaultFetch<Impl>::buildInst(ThreadID tid, StaticInstPtr staticInst,
+ StaticInstPtr curMacroop, TheISA::PCState thisPC,
+ TheISA::PCState nextPC, bool trace)
+{
+ // Get a sequence number.
+ InstSeqNum seq = cpu->getAndIncrementInstSeq();
+
+ // Create a new DynInst from the instruction fetched.
+ DynInstPtr instruction =
+ new DynInst(staticInst, thisPC, nextPC, seq, cpu);
+ instruction->setTid(tid);
+
+ instruction->setASID(tid);
+
+ instruction->setThreadState(cpu->thread[tid]);
+
+ DPRINTF(Fetch, "[tid:%i]: Instruction PC %#x (%d) created "
+ "[sn:%lli]\n", tid, thisPC.instAddr(),
+ thisPC.microPC(), seq);
+
+ DPRINTF(Fetch, "[tid:%i]: Instruction is: %s\n", tid,
+ instruction->staticInst->
+ disassemble(thisPC.instAddr()));
+
+#if TRACING_ON
+ if (trace) {
+ instruction->traceData =
+ cpu->getTracer()->getInstRecord(curTick, cpu->tcBase(tid),
+ instruction->staticInst, thisPC, curMacroop);
+ }
+#else
+ instruction->traceData = NULL;
+#endif
+
+ // Add instruction to the CPU's list of instructions.
+ instruction->setInstListIt(cpu->addInst(instruction));
+
+ // Write the instruction to the first slot in the queue
+ // that heads to decode.
+ assert(numInst < fetchWidth);
+ toDecode->insts[toDecode->size++] = instruction;
+
+ return instruction;
+}
+
template<class Impl>
void
DefaultFetch<Impl>::fetch(bool &status_change)
DPRINTF(Fetch, "Attempting to fetch from [tid:%i]\n", tid);
// The current PC.
- TheISA::PCState fetchPC = pc[tid];
+ TheISA::PCState thisPC = pc[tid];
// Fault code for memory access.
Fault fault = NoFault;
+ Addr pcOffset = fetchOffset[tid];
+ Addr fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask;
+
// If returning from the delay of a cache miss, then update the status
// to running, otherwise do the cache access. Possibly move this up
// to tick() function.
if (fetchStatus[tid] == IcacheAccessComplete) {
- DPRINTF(Fetch, "[tid:%i]: Icache miss is complete.\n",
- tid);
+ DPRINTF(Fetch, "[tid:%i]: Icache miss is complete.\n",tid);
fetchStatus[tid] = Running;
status_change = true;
} else if (fetchStatus[tid] == Running) {
DPRINTF(Fetch, "[tid:%i]: Attempting to translate and read "
- "instruction, starting at PC %s.\n", tid, fetchPC);
+ "instruction, starting at PC %#x.\n", tid, fetchAddr);
- bool fetch_success = fetchCacheLine(fetchPC.instAddr(), fault, tid);
+ bool fetch_success = fetchCacheLine(fetchAddr, fault, tid,
+ thisPC.instAddr());
if (!fetch_success) {
if (cacheBlocked) {
++icacheStallCycles;
return;
}
- TheISA::PCState nextPC = fetchPC;
-
- InstSeqNum inst_seq;
- MachInst inst;
- ExtMachInst ext_inst;
+ TheISA::PCState nextPC = thisPC;
StaticInstPtr staticInst = NULL;
- StaticInstPtr macroop = NULL;
+ StaticInstPtr curMacroop = macroop[tid];
if (fault == NoFault) {
- //XXX Masking out pal mode bit. This will break x86. Alpha needs
- //to pull the pal mode bit ouf ot the instruction address.
- unsigned offset = (fetchPC.instAddr() & ~1) - cacheDataPC[tid];
- assert(offset < cacheBlkSize);
// If the read of the first instruction was successful, then grab the
// instructions from the rest of the cache line and put them into the
// queue heading to decode.
- DPRINTF(Fetch, "[tid:%i]: Adding instructions to queue to "
- "decode.\n",tid);
+ DPRINTF(Fetch,
+ "[tid:%i]: Adding instructions to queue to decode.\n", tid);
// Need to keep track of whether or not a predicted branch
// ended this fetch block.
- bool predicted_branch = false;
+ bool predictedBranch = false;
- while (offset < cacheBlkSize &&
- numInst < fetchWidth &&
- !predicted_branch) {
+ TheISA::MachInst *cacheInsts =
+ reinterpret_cast<TheISA::MachInst *>(cacheData[tid]);
- // Make sure this is a valid index.
- assert(offset <= cacheBlkSize - instSize);
+ const unsigned numInsts = cacheBlkSize / instSize;
+ unsigned blkOffset = (fetchAddr - cacheDataPC[tid]) / instSize;
- if (!macroop) {
- // Get the instruction from the array of the cache line.
- inst = TheISA::gtoh(*reinterpret_cast<TheISA::MachInst *>
- (&cacheData[tid][offset]));
+ // Loop through instruction memory from the cache.
+ while (blkOffset < numInsts &&
+ numInst < fetchWidth &&
+ !predictedBranch) {
+
+ // If we need to process more memory, do it now.
+ if (!curMacroop && !predecoder.extMachInstReady()) {
+ if (ISA_HAS_DELAY_SLOT && pcOffset == 0) {
+ // Walk past any annulled delay slot instructions.
+ Addr pcAddr = thisPC.instAddr() & BaseCPU::PCMask;
+ while (fetchAddr != pcAddr && blkOffset < numInsts) {
+ blkOffset++;
+ fetchAddr += instSize;
+ }
+ if (blkOffset >= numInsts)
+ break;
+ }
+ MachInst inst = TheISA::gtoh(cacheInsts[blkOffset]);
predecoder.setTC(cpu->thread[tid]->getTC());
- predecoder.moreBytes(fetchPC, fetchPC.instAddr(), inst);
+ predecoder.moreBytes(thisPC, fetchAddr, inst);
- ext_inst = predecoder.getExtMachInst(fetchPC);
- staticInst = StaticInstPtr(ext_inst, fetchPC.instAddr());
- if (staticInst->isMacroop())
- macroop = staticInst;
+ if (predecoder.needMoreBytes()) {
+ blkOffset++;
+ fetchAddr += instSize;
+ pcOffset += instSize;
+ }
}
+
+ // Extract as many instructions and/or microops as we can from
+ // the memory we've processed so far.
do {
- if (macroop) {
- staticInst = macroop->fetchMicroop(fetchPC.microPC());
+ if (!curMacroop) {
+ if (predecoder.extMachInstReady()) {
+ ExtMachInst extMachInst;
+
+ extMachInst = predecoder.getExtMachInst(thisPC);
+ pcOffset = 0;
+ staticInst = StaticInstPtr(extMachInst,
+ thisPC.instAddr());
+
+ // Increment stat of fetched instructions.
+ ++fetchedInsts;
+
+ if (staticInst->isMacroop())
+ curMacroop = staticInst;
+ } else {
+ // We need more bytes for this instruction.
+ break;
+ }
+ }
+ if (curMacroop) {
+ staticInst = curMacroop->fetchMicroop(thisPC.microPC());
if (staticInst->isLastMicroop())
- macroop = NULL;
+ curMacroop = NULL;
}
- // Get a sequence number.
- inst_seq = cpu->getAndIncrementInstSeq();
-
- // Create a new DynInst from the instruction fetched.
- DynInstPtr instruction = new DynInst(staticInst,
- fetchPC, nextPC,
- inst_seq, cpu);
- instruction->setTid(tid);
-
- instruction->setASID(tid);
-
- instruction->setThreadState(cpu->thread[tid]);
-
- DPRINTF(Fetch, "[tid:%i]: Instruction PC %s (%d) created "
- "[sn:%lli]\n", tid, instruction->pcState(),
- instruction->microPC(), inst_seq);
+ DynInstPtr instruction =
+ buildInst(tid, staticInst, curMacroop,
+ thisPC, nextPC, true);
- //DPRINTF(Fetch, "[tid:%i]: MachInst is %#x\n", tid, ext_inst);
+ numInst++;
- DPRINTF(Fetch, "[tid:%i]: Instruction is: %s\n", tid,
- instruction->staticInst->
- disassemble(fetchPC.instAddr()));
-
-#if TRACING_ON
- instruction->traceData =
- cpu->getTracer()->getInstRecord(curTick, cpu->tcBase(tid),
- instruction->staticInst, fetchPC, macroop);
-#else
- instruction->traceData = NULL;
-#endif
+ nextPC = thisPC;
// If we're branching after this instruction, quite fetching
// from the same block then.
- predicted_branch = fetchPC.branching();
- predicted_branch |=
+ predictedBranch |= thisPC.branching();
+ predictedBranch |=
lookupAndUpdateNextPC(instruction, nextPC);
- if (predicted_branch) {
- DPRINTF(Fetch, "Branch detected with PC = %s\n", fetchPC);
+ if (predictedBranch) {
+ DPRINTF(Fetch, "Branch detected with PC = %s\n", thisPC);
}
- // Add instruction to the CPU's list of instructions.
- instruction->setInstListIt(cpu->addInst(instruction));
-
- // Write the instruction to the first slot in the queue
- // that heads to decode.
- toDecode->insts[numInst] = instruction;
-
- toDecode->size++;
-
- // Increment stat of fetched instructions.
- ++fetchedInsts;
-
// Move to the next instruction, unless we have a branch.
- fetchPC = nextPC;
+ thisPC = nextPC;
if (instruction->isQuiesce()) {
- DPRINTF(Fetch, "Quiesce instruction encountered, halting fetch!",
- curTick);
+ DPRINTF(Fetch,
+ "Quiesce instruction encountered, halting fetch!");
fetchStatus[tid] = QuiescePending;
- ++numInst;
status_change = true;
break;
}
-
- ++numInst;
- } while (staticInst->isMicroop() &&
- !staticInst->isLastMicroop() &&
+ } while ((curMacroop || predecoder.extMachInstReady()) &&
numInst < fetchWidth);
- //XXX Masking out pal mode bit.
- offset = (fetchPC.instAddr() & ~1) - cacheDataPC[tid];
}
- if (predicted_branch) {
+ if (predictedBranch) {
DPRINTF(Fetch, "[tid:%i]: Done fetching, predicted branch "
"instruction encountered.\n", tid);
} else if (numInst >= fetchWidth) {
DPRINTF(Fetch, "[tid:%i]: Done fetching, reached fetch bandwidth "
"for this cycle.\n", tid);
- } else if (offset >= cacheBlkSize) {
+ } else if (blkOffset >= cacheBlkSize) {
DPRINTF(Fetch, "[tid:%i]: Done fetching, reached the end of cache "
"block.\n", tid);
}
}
+ macroop[tid] = curMacroop;
+ fetchOffset[tid] = pcOffset;
+
if (numInst > 0) {
wroteToTimeBuffer = true;
}
// Send the fault to commit. This thread will not do anything
// until commit handles the fault. The only other way it can
- // wake up is if a squash comes along and changes the PC.
- assert(numInst < fetchWidth);
- // Get a sequence number.
- inst_seq = cpu->getAndIncrementInstSeq();
- // We will use a nop in order to carry the fault.
- ext_inst = TheISA::NoopMachInst;
-
- // Create a new DynInst from the dummy nop.
- DynInstPtr instruction = new DynInst(ext_inst, fetchPC, nextPC,
- inst_seq, cpu);
- TheISA::advancePC(nextPC, instruction->staticInst);
- instruction->setPredTarg(nextPC);
- instruction->setTid(tid);
-
- instruction->setASID(tid);
+ // wake up is if a squash comes along and changes the PC. Send the
+ // fault on a dummy nop.
+ staticInst = StaticInstPtr(TheISA::NoopMachInst, thisPC.instAddr());
- instruction->setThreadState(cpu->thread[tid]);
-
- instruction->traceData = NULL;
-
- instruction->setInstListIt(cpu->addInst(instruction));
+ DynInstPtr instruction =
+ buildInst(tid, staticInst, NULL, thisPC, nextPC, false);
+ TheISA::advancePC(nextPC, staticInst);
+ instruction->setPredTarg(nextPC);
instruction->fault = fault;
- toDecode->insts[numInst] = instruction;
- toDecode->size++;
-
- wroteToTimeBuffer = true;
-
DPRINTF(Fetch, "[tid:%i]: Blocked, need to handle the trap.\n",tid);
fetchStatus[tid] = TrapPending;
status_change = true;
DPRINTF(Fetch, "[tid:%i]: fault (%s) detected @ PC %s",
- tid, fault->name(), pc[tid]);
+ tid, fault->name(), thisPC);
}
}
projects / gem5.git / commitdiff