gem5/cpu/o3/fetch_impl.hh
Gabe Black 10c79efe55 Changed the fault enum into a class, and fixed everything up to work with it. Next, the faults need to be pulled out of all the other code so that they are only used to communicate between the CPU and the ISA.
SConscript:
    The new faults.cc file in sim allocates the system wide faults. When these faults are generated through a function interface in the ISA, this file may go away.
arch/alpha/alpha_memory.cc:
    Changed Fault to Fault * and took the underscores out of fault names.
arch/alpha/alpha_memory.hh:
    Changed Fault to Fault *. Also, added an include for the alpha faults.
arch/alpha/ev5.cc:
    Changed the fault_addr array into a fault_addr function. Once all of the faults can be expected to have the same type, fault_addr can go away completely and the info it provided will come from the fault itself. Also, Fault was changed to Fault *, and underscores were taken out of fault names.
arch/alpha/isa/decoder.isa:
    Changed Fault to Fault * and took the underscores out fault names.
arch/alpha/isa/fp.isa:
    Changed Fault to Fault *, and took the underscores out of fault names.
arch/alpha/isa/main.isa:
    Changed Fault to Fault *, removed underscores from fault names, and made an include of the alpha faults show up in all the generated files.
arch/alpha/isa/mem.isa:
    Changed Fault to Fault * and removed underscores from fault names.
arch/alpha/isa/unimp.isa:
arch/alpha/isa/unknown.isa:
cpu/exec_context.hh:
cpu/ozone/cpu.hh:
cpu/simple/cpu.cc:
dev/alpha_console.cc:
dev/ide_ctrl.cc:
dev/isa_fake.cc:
dev/pciconfigall.cc:
dev/pcidev.cc:
dev/pcidev.hh:
dev/tsunami_cchip.cc:
dev/tsunami_io.cc:
dev/tsunami_pchip.cc:
    Changed Fault to Fault *, and removed underscores from fault names.
arch/alpha/isa_traits.hh:
    Changed the include of arch/alpha/faults.hh to sim/faults.hh, since the alpha faults weren't needed.
cpu/base_dyn_inst.cc:
    Changed Fault to Fault *, and removed underscores from fault names. This file probably shouldn't use the Unimplemented Opcode fault.
cpu/base_dyn_inst.hh:
    Changed Fault to Fault * and took the underscores out of the fault names.
cpu/exec_context.cc:
cpu/o3/alpha_dyn_inst.hh:
cpu/o3/alpha_dyn_inst_impl.hh:
cpu/o3/fetch.hh:
dev/alpha_console.hh:
dev/baddev.hh:
dev/ide_ctrl.hh:
dev/isa_fake.hh:
dev/ns_gige.hh:
dev/pciconfigall.hh:
dev/sinic.hh:
dev/tsunami_cchip.hh:
dev/tsunami_io.hh:
dev/tsunami_pchip.hh:
dev/uart.hh:
dev/uart8250.hh:
    Changed Fault to Fault *.
cpu/o3/alpha_cpu.hh:
    Changed Fault to Fault *, removed underscores from fault names.
cpu/o3/alpha_cpu_impl.hh:
    Changed Fault to Fault *, removed underscores from fault names, and changed the fault_addr array to the fault_addr function. Once all faults are from the ISA, this function will probably go away.
cpu/o3/commit_impl.hh:
cpu/o3/fetch_impl.hh:
dev/baddev.cc:
    Changed Fault to Fault *, and removed underscores from the fault names.
cpu/o3/regfile.hh:
    Added an include for the alpha specific faults which will hopefully go away once the ipr stuff is moved, changed Fault to Fault *, and removed the underscores from fault names.
cpu/simple/cpu.hh:
    Changed Fault to Fault *
dev/ns_gige.cc:
    Changed Fault to Fault *, and removdd underscores from fault names.
dev/sinic.cc:
    Changed Fault to Fault *, and removed the underscores from fault names.
dev/uart8250.cc:
    Chanted Fault to Fault *, and removed underscores from fault names.
kern/kernel_stats.cc:
    Removed underscores from fault names, and from NumFaults.
kern/kernel_stats.hh:
    Changed the predeclaration of Fault from an enum to a class, and changd the "fault" function to work with the classes instead of the enum. Once there are no system wide faults anymore, this code will simplify back to something like it was originally.
sim/faults.cc:
    This allocates the system wide faults.
sim/faults.hh:
    This declares the system wide faults.
sim/syscall_emul.cc:
sim/syscall_emul.hh:
    Removed the underscores from fault names.

--HG--
rename : arch/alpha/faults.cc => sim/faults.cc
rename : arch/alpha/faults.hh => sim/faults.hh
extra : convert_revision : 253d39258237333ae8ec4d8047367cb3ea68569d
2006-02-16 01:22:51 -05:00

617 lines
20 KiB
C++

/*
* Copyright (c) 2004-2005 The Regents of The University of Michigan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
// Remove this later; used only for debugging.
#define OPCODE(X) (X >> 26) & 0x3f
#include "arch/isa_traits.hh"
#include "sim/byteswap.hh"
#include "cpu/exetrace.hh"
#include "mem/base_mem.hh"
#include "mem/mem_interface.hh"
#include "mem/mem_req.hh"
#include "cpu/o3/fetch.hh"
#include "sim/root.hh"
template<class Impl>
SimpleFetch<Impl>::CacheCompletionEvent
::CacheCompletionEvent(SimpleFetch *_fetch)
: Event(&mainEventQueue),
fetch(_fetch)
{
}
template<class Impl>
void
SimpleFetch<Impl>::CacheCompletionEvent::process()
{
fetch->processCacheCompletion();
}
template<class Impl>
const char *
SimpleFetch<Impl>::CacheCompletionEvent::description()
{
return "SimpleFetch cache completion event";
}
template<class Impl>
SimpleFetch<Impl>::SimpleFetch(Params &params)
: icacheInterface(params.icacheInterface),
branchPred(params),
decodeToFetchDelay(params.decodeToFetchDelay),
renameToFetchDelay(params.renameToFetchDelay),
iewToFetchDelay(params.iewToFetchDelay),
commitToFetchDelay(params.commitToFetchDelay),
fetchWidth(params.fetchWidth)
{
DPRINTF(Fetch, "Fetch: Fetch constructor called\n");
// Set status to idle.
_status = Idle;
// Create a new memory request.
memReq = new MemReq();
// Not sure of this parameter. I think it should be based on the
// thread number.
#if !FULL_SYSTEM
memReq->asid = 0;
#else
memReq->asid = 0;
#endif // FULL_SYSTEM
memReq->data = new uint8_t[64];
// Size of cache block.
cacheBlkSize = icacheInterface ? icacheInterface->getBlockSize() : 64;
// Create mask to get rid of offset bits.
cacheBlkMask = (cacheBlkSize - 1);
// Get the size of an instruction.
instSize = sizeof(MachInst);
// Create space to store a cache line.
cacheData = new uint8_t[cacheBlkSize];
}
template <class Impl>
void
SimpleFetch<Impl>::regStats()
{
icacheStallCycles
.name(name() + ".icacheStallCycles")
.desc("Number of cycles fetch is stalled on an Icache miss")
.prereq(icacheStallCycles);
fetchedInsts
.name(name() + ".fetchedInsts")
.desc("Number of instructions fetch has processed")
.prereq(fetchedInsts);
predictedBranches
.name(name() + ".predictedBranches")
.desc("Number of branches that fetch has predicted taken")
.prereq(predictedBranches);
fetchCycles
.name(name() + ".fetchCycles")
.desc("Number of cycles fetch has run and was not squashing or"
" blocked")
.prereq(fetchCycles);
fetchSquashCycles
.name(name() + ".fetchSquashCycles")
.desc("Number of cycles fetch has spent squashing")
.prereq(fetchSquashCycles);
fetchBlockedCycles
.name(name() + ".fetchBlockedCycles")
.desc("Number of cycles fetch has spent blocked")
.prereq(fetchBlockedCycles);
fetchedCacheLines
.name(name() + ".fetchedCacheLines")
.desc("Number of cache lines fetched")
.prereq(fetchedCacheLines);
fetch_nisn_dist
.init(/* base value */ 0,
/* last value */ fetchWidth,
/* bucket size */ 1)
.name(name() + ".FETCH:rate_dist")
.desc("Number of instructions fetched each cycle (Total)")
.flags(Stats::pdf)
;
branchPred.regStats();
}
template<class Impl>
void
SimpleFetch<Impl>::setCPU(FullCPU *cpu_ptr)
{
DPRINTF(Fetch, "Fetch: Setting the CPU pointer.\n");
cpu = cpu_ptr;
// This line will be removed eventually.
memReq->xc = cpu->xcBase();
}
template<class Impl>
void
SimpleFetch<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *time_buffer)
{
DPRINTF(Fetch, "Fetch: Setting the time buffer pointer.\n");
timeBuffer = time_buffer;
// Create wires to get information from proper places in time buffer.
fromDecode = timeBuffer->getWire(-decodeToFetchDelay);
fromRename = timeBuffer->getWire(-renameToFetchDelay);
fromIEW = timeBuffer->getWire(-iewToFetchDelay);
fromCommit = timeBuffer->getWire(-commitToFetchDelay);
}
template<class Impl>
void
SimpleFetch<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr)
{
DPRINTF(Fetch, "Fetch: Setting the fetch queue pointer.\n");
fetchQueue = fq_ptr;
// Create wire to write information to proper place in fetch queue.
toDecode = fetchQueue->getWire(0);
}
template<class Impl>
void
SimpleFetch<Impl>::processCacheCompletion()
{
DPRINTF(Fetch, "Fetch: Waking up from cache miss.\n");
// Only change the status if it's still waiting on the icache access
// to return.
// Can keep track of how many cache accesses go unused due to
// misspeculation here.
if (_status == IcacheMissStall)
_status = IcacheMissComplete;
}
template <class Impl>
bool
SimpleFetch<Impl>::lookupAndUpdateNextPC(DynInstPtr &inst, Addr &next_PC)
{
// Do branch prediction check here.
// A bit of a misnomer...next_PC is actually the current PC until
// this function updates it.
bool predict_taken;
if (!inst->isControl()) {
next_PC = next_PC + instSize;
inst->setPredTarg(next_PC);
return false;
}
predict_taken = branchPred.predict(inst, next_PC);
if (predict_taken) {
++predictedBranches;
}
return predict_taken;
}
template <class Impl>
Fault *
SimpleFetch<Impl>::fetchCacheLine(Addr fetch_PC)
{
// Check if the instruction exists within the cache.
// If it does, then proceed on to read the instruction and the rest
// of the instructions in the cache line until either the end of the
// cache line or a predicted taken branch is encountered.
#if FULL_SYSTEM
// Flag to say whether or not address is physical addr.
unsigned flags = cpu->inPalMode() ? PHYSICAL : 0;
#else
unsigned flags = 0;
#endif // FULL_SYSTEM
Fault * fault = NoFault;
// Align the fetch PC so it's at the start of a cache block.
fetch_PC = icacheBlockAlignPC(fetch_PC);
// Setup the memReq to do a read of the first isntruction's address.
// Set the appropriate read size and flags as well.
memReq->cmd = Read;
memReq->reset(fetch_PC, cacheBlkSize, flags);
// Translate the instruction request.
// Should this function be
// in the CPU class ? Probably...ITB/DTB should exist within the
// CPU.
fault = cpu->translateInstReq(memReq);
// In the case of faults, the fetch stage may need to stall and wait
// on what caused the fetch (ITB or Icache miss).
// If translation was successful, attempt to read the first
// instruction.
if (fault == NoFault) {
DPRINTF(Fetch, "Fetch: Doing instruction read.\n");
fault = cpu->mem->read(memReq, cacheData);
// This read may change when the mem interface changes.
fetchedCacheLines++;
}
// Now do the timing access to see whether or not the instruction
// exists within the cache.
if (icacheInterface && fault == NoFault) {
DPRINTF(Fetch, "Fetch: Doing timing memory access.\n");
memReq->completionEvent = NULL;
memReq->time = curTick;
MemAccessResult result = icacheInterface->access(memReq);
// If the cache missed (in this model functional and timing
// memories are different), then schedule an event to wake
// up this stage once the cache miss completes.
if (result != MA_HIT && icacheInterface->doEvents()) {
memReq->completionEvent = new CacheCompletionEvent(this);
// How does current model work as far as individual
// stages scheduling/unscheduling?
// Perhaps have only the main CPU scheduled/unscheduled,
// and have it choose what stages to run appropriately.
DPRINTF(Fetch, "Fetch: Stalling due to icache miss.\n");
_status = IcacheMissStall;
}
}
return fault;
}
template <class Impl>
inline void
SimpleFetch<Impl>::doSquash(const Addr &new_PC)
{
DPRINTF(Fetch, "Fetch: Squashing, setting PC to: %#x.\n", new_PC);
cpu->setNextPC(new_PC + instSize);
cpu->setPC(new_PC);
// Clear the icache miss if it's outstanding.
if (_status == IcacheMissStall && icacheInterface) {
DPRINTF(Fetch, "Fetch: Squashing outstanding Icache miss.\n");
// @todo: Use an actual thread number here.
icacheInterface->squash(0);
}
_status = Squashing;
++fetchSquashCycles;
}
template<class Impl>
void
SimpleFetch<Impl>::squashFromDecode(const Addr &new_PC,
const InstSeqNum &seq_num)
{
DPRINTF(Fetch, "Fetch: Squashing from decode.\n");
doSquash(new_PC);
// Tell the CPU to remove any instructions that are in flight between
// fetch and decode.
cpu->removeInstsUntil(seq_num);
}
template <class Impl>
void
SimpleFetch<Impl>::squash(const Addr &new_PC)
{
DPRINTF(Fetch, "Fetch: Squash from commit.\n");
doSquash(new_PC);
// Tell the CPU to remove any instructions that are not in the ROB.
cpu->removeInstsNotInROB();
}
template<class Impl>
void
SimpleFetch<Impl>::tick()
{
// Check squash signals from commit.
if (fromCommit->commitInfo.squash) {
DPRINTF(Fetch, "Fetch: Squashing instructions due to squash "
"from commit.\n");
// In any case, squash.
squash(fromCommit->commitInfo.nextPC);
// Also check if there's a mispredict that happened.
if (fromCommit->commitInfo.branchMispredict) {
branchPred.squash(fromCommit->commitInfo.doneSeqNum,
fromCommit->commitInfo.nextPC,
fromCommit->commitInfo.branchTaken);
} else {
branchPred.squash(fromCommit->commitInfo.doneSeqNum);
}
return;
} else if (fromCommit->commitInfo.doneSeqNum) {
// Update the branch predictor if it wasn't a squashed instruction
// that was braodcasted.
branchPred.update(fromCommit->commitInfo.doneSeqNum);
}
// Check ROB squash signals from commit.
if (fromCommit->commitInfo.robSquashing) {
DPRINTF(Fetch, "Fetch: ROB is still squashing.\n");
// Continue to squash.
_status = Squashing;
++fetchSquashCycles;
return;
}
// Check squash signals from decode.
if (fromDecode->decodeInfo.squash) {
DPRINTF(Fetch, "Fetch: Squashing instructions due to squash "
"from decode.\n");
// Update the branch predictor.
if (fromDecode->decodeInfo.branchMispredict) {
branchPred.squash(fromDecode->decodeInfo.doneSeqNum,
fromDecode->decodeInfo.nextPC,
fromDecode->decodeInfo.branchTaken);
} else {
branchPred.squash(fromDecode->decodeInfo.doneSeqNum);
}
if (_status != Squashing) {
// Squash unless we're already squashing?
squashFromDecode(fromDecode->decodeInfo.nextPC,
fromDecode->decodeInfo.doneSeqNum);
return;
}
}
// Check if any of the stall signals are high.
if (fromDecode->decodeInfo.stall ||
fromRename->renameInfo.stall ||
fromIEW->iewInfo.stall ||
fromCommit->commitInfo.stall)
{
// Block stage, regardless of current status.
DPRINTF(Fetch, "Fetch: Stalling stage.\n");
DPRINTF(Fetch, "Fetch: Statuses: Decode: %i Rename: %i IEW: %i "
"Commit: %i\n",
fromDecode->decodeInfo.stall,
fromRename->renameInfo.stall,
fromIEW->iewInfo.stall,
fromCommit->commitInfo.stall);
_status = Blocked;
++fetchBlockedCycles;
return;
} else if (_status == Blocked) {
// Unblock stage if status is currently blocked and none of the
// stall signals are being held high.
_status = Running;
++fetchBlockedCycles;
return;
}
// If fetch has reached this point, then there are no squash signals
// still being held high. Check if fetch is in the squashing state;
// if so, fetch can switch to running.
// Similarly, there are no blocked signals still being held high.
// Check if fetch is in the blocked state; if so, fetch can switch to
// running.
if (_status == Squashing) {
DPRINTF(Fetch, "Fetch: Done squashing, switching to running.\n");
// Switch status to running
_status = Running;
++fetchCycles;
fetch();
} else if (_status != IcacheMissStall) {
DPRINTF(Fetch, "Fetch: Running stage.\n");
++fetchCycles;
fetch();
}
}
template<class Impl>
void
SimpleFetch<Impl>::fetch()
{
//////////////////////////////////////////
// Start actual fetch
//////////////////////////////////////////
// The current PC.
Addr fetch_PC = cpu->readPC();
// Fault code for memory access.
Fault * fault = NoFault;
// 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 (_status == IcacheMissComplete) {
DPRINTF(Fetch, "Fetch: Icache miss is complete.\n");
// Reset the completion event to NULL.
memReq->completionEvent = NULL;
_status = Running;
} else {
DPRINTF(Fetch, "Fetch: Attempting to translate and read "
"instruction, starting at PC %08p.\n",
fetch_PC);
fault = fetchCacheLine(fetch_PC);
}
// If we had a stall due to an icache miss, then return. It'd
// be nicer if this were handled through the kind of fault that
// is returned by the function.
if (_status == IcacheMissStall) {
return;
}
// As far as timing goes, the CPU will need to send an event through
// the MemReq in order to be woken up once the memory access completes.
// Probably have a status on a per thread basis so each thread can
// block independently and be woken up independently.
Addr next_PC = fetch_PC;
InstSeqNum inst_seq;
MachInst inst;
unsigned offset = fetch_PC & cacheBlkMask;
unsigned fetched;
if (fault == NoFault) {
// 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, "Fetch: Adding instructions to queue to decode.\n");
//////////////////////////
// Fetch first instruction
//////////////////////////
// Need to keep track of whether or not a predicted branch
// ended this fetch block.
bool predicted_branch = false;
for (fetched = 0;
offset < cacheBlkSize &&
fetched < fetchWidth &&
!predicted_branch;
++fetched)
{
// Get a sequence number.
inst_seq = cpu->getAndIncrementInstSeq();
// Make sure this is a valid index.
assert(offset <= cacheBlkSize - instSize);
// Get the instruction from the array of the cache line.
inst = gtoh(*reinterpret_cast<MachInst *>
(&cacheData[offset]));
// Create a new DynInst from the instruction fetched.
DynInstPtr instruction = new DynInst(inst, fetch_PC, next_PC,
inst_seq, cpu);
DPRINTF(Fetch, "Fetch: Instruction %i created, with PC %#x\n",
inst_seq, instruction->readPC());
DPRINTF(Fetch, "Fetch: Instruction opcode is: %03p\n",
OPCODE(inst));
instruction->traceData =
Trace::getInstRecord(curTick, cpu->xcBase(), cpu,
instruction->staticInst,
instruction->readPC(), 0);
predicted_branch = lookupAndUpdateNextPC(instruction, next_PC);
// Add instruction to the CPU's list of instructions.
cpu->addInst(instruction);
// Write the instruction to the first slot in the queue
// that heads to decode.
toDecode->insts[fetched] = instruction;
toDecode->size++;
// Increment stat of fetched instructions.
++fetchedInsts;
// Move to the next instruction, unless we have a branch.
fetch_PC = next_PC;
offset+= instSize;
}
fetch_nisn_dist.sample(fetched);
}
// Now that fetching is completed, update the PC to signify what the next
// cycle will be. Might want to move this to the beginning of this
// function so that the PC updates at the beginning of everything.
// Or might want to leave setting the PC to the main CPU, with fetch
// only changing the nextPC (will require correct determination of
// next PC).
if (fault == NoFault) {
DPRINTF(Fetch, "Fetch: Setting PC to %08p.\n", next_PC);
cpu->setPC(next_PC);
cpu->setNextPC(next_PC + instSize);
} else {
// If the issue was an icache miss, then we can just return and
// wait until it is handled.
if (_status == IcacheMissStall) {
return;
}
// Handle the fault.
// This stage will not be able to continue until all the ROB
// slots are empty, at which point the fault can be handled.
// The only other way it can wake up is if a squash comes along
// and changes the PC. Not sure how to handle that case...perhaps
// have it handled by the upper level CPU class which peeks into the
// time buffer and sees if a squash comes along, in which case it
// changes the status.
DPRINTF(Fetch, "Fetch: Blocked, need to handle the trap.\n");
_status = Blocked;
#if FULL_SYSTEM
// cpu->trap(fault);
// Send a signal to the ROB indicating that there's a trap from the
// fetch stage that needs to be handled. Need to indicate that
// there's a fault, and the fault type.
#else // !FULL_SYSTEM
fatal("fault (%d) detected @ PC %08p", fault, cpu->readPC());
#endif // FULL_SYSTEM
}
}