gem5/cpu/o3/inst_queue_impl.hh
Ali Saidi fb7899aa68 fix problems on darwin/*BSD for syscall emulation mode
arch/alpha/alpha_linux_process.cc:
arch/alpha/alpha_tru64_process.cc:
    fixup for bsd hosts. Some headers are included by default which means that
    more variables need TGT_ prefixes and there isn't a stat call (everything
    is a stat64 call) so we have to work around that a bit
base/intmath.hh:
base/socket.cc:
    this is no longer needed with mac os 10.4
cpu/inst_seq.hh:
    just use a uint64_t instead of long long
cpu/o3/inst_queue_impl.hh:
    I much cleaner way to get max int
sim/syscall_emul.hh:
    fix stat64 problems on *BSD

--HG--
extra : convert_revision : 9eef5f896e083ae1774e818a9765dd83e0305942
2006-02-10 14:21:32 -05:00

1136 lines
34 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.
*/
// Todo:
// Current ordering allows for 0 cycle added-to-scheduled. Could maybe fake
// it; either do in reverse order, or have added instructions put into a
// different ready queue that, in scheduleRreadyInsts(), gets put onto the
// normal ready queue. This would however give only a one cycle delay,
// but probably is more flexible to actually add in a delay parameter than
// just running it backwards.
#include <limits>
#include <vector>
#include "sim/root.hh"
#include "cpu/o3/inst_queue.hh"
// Either compile error or max int due to sign extension.
// Hack to avoid compile warnings.
const InstSeqNum MaxInstSeqNum = std::numeric_limits<InstSeqNum>::max();
template <class Impl>
InstructionQueue<Impl>::InstructionQueue(Params &params)
: memDepUnit(params),
numEntries(params.numIQEntries),
intWidth(params.executeIntWidth),
floatWidth(params.executeFloatWidth),
branchWidth(params.executeBranchWidth),
memoryWidth(params.executeMemoryWidth),
totalWidth(params.issueWidth),
numPhysIntRegs(params.numPhysIntRegs),
numPhysFloatRegs(params.numPhysFloatRegs),
commitToIEWDelay(params.commitToIEWDelay)
{
// Initialize the number of free IQ entries.
freeEntries = numEntries;
// Set the number of physical registers as the number of int + float
numPhysRegs = numPhysIntRegs + numPhysFloatRegs;
DPRINTF(IQ, "IQ: There are %i physical registers.\n", numPhysRegs);
//Create an entry for each physical register within the
//dependency graph.
dependGraph = new DependencyEntry[numPhysRegs];
// Resize the register scoreboard.
regScoreboard.resize(numPhysRegs);
// Initialize all the head pointers to point to NULL, and all the
// entries as unready.
// Note that in actuality, the registers corresponding to the logical
// registers start off as ready. However this doesn't matter for the
// IQ as the instruction should have been correctly told if those
// registers are ready in rename. Thus it can all be initialized as
// unready.
for (int i = 0; i < numPhysRegs; ++i)
{
dependGraph[i].next = NULL;
dependGraph[i].inst = NULL;
regScoreboard[i] = false;
}
}
template <class Impl>
void
InstructionQueue<Impl>::regStats()
{
iqInstsAdded
.name(name() + ".iqInstsAdded")
.desc("Number of instructions added to the IQ (excludes non-spec)")
.prereq(iqInstsAdded);
iqNonSpecInstsAdded
.name(name() + ".iqNonSpecInstsAdded")
.desc("Number of non-speculative instructions added to the IQ")
.prereq(iqNonSpecInstsAdded);
// iqIntInstsAdded;
iqIntInstsIssued
.name(name() + ".iqIntInstsIssued")
.desc("Number of integer instructions issued")
.prereq(iqIntInstsIssued);
// iqFloatInstsAdded;
iqFloatInstsIssued
.name(name() + ".iqFloatInstsIssued")
.desc("Number of float instructions issued")
.prereq(iqFloatInstsIssued);
// iqBranchInstsAdded;
iqBranchInstsIssued
.name(name() + ".iqBranchInstsIssued")
.desc("Number of branch instructions issued")
.prereq(iqBranchInstsIssued);
// iqMemInstsAdded;
iqMemInstsIssued
.name(name() + ".iqMemInstsIssued")
.desc("Number of memory instructions issued")
.prereq(iqMemInstsIssued);
// iqMiscInstsAdded;
iqMiscInstsIssued
.name(name() + ".iqMiscInstsIssued")
.desc("Number of miscellaneous instructions issued")
.prereq(iqMiscInstsIssued);
iqSquashedInstsIssued
.name(name() + ".iqSquashedInstsIssued")
.desc("Number of squashed instructions issued")
.prereq(iqSquashedInstsIssued);
iqLoopSquashStalls
.name(name() + ".iqLoopSquashStalls")
.desc("Number of times issue loop had to restart due to squashed "
"inst; mainly for profiling")
.prereq(iqLoopSquashStalls);
iqSquashedInstsExamined
.name(name() + ".iqSquashedInstsExamined")
.desc("Number of squashed instructions iterated over during squash;"
" mainly for profiling")
.prereq(iqSquashedInstsExamined);
iqSquashedOperandsExamined
.name(name() + ".iqSquashedOperandsExamined")
.desc("Number of squashed operands that are examined and possibly "
"removed from graph")
.prereq(iqSquashedOperandsExamined);
iqSquashedNonSpecRemoved
.name(name() + ".iqSquashedNonSpecRemoved")
.desc("Number of squashed non-spec instructions that were removed")
.prereq(iqSquashedNonSpecRemoved);
// Tell mem dependence unit to reg stats as well.
memDepUnit.regStats();
}
template <class Impl>
void
InstructionQueue<Impl>::setCPU(FullCPU *cpu_ptr)
{
cpu = cpu_ptr;
tail = cpu->instList.begin();
}
template <class Impl>
void
InstructionQueue<Impl>::setIssueToExecuteQueue(
TimeBuffer<IssueStruct> *i2e_ptr)
{
DPRINTF(IQ, "IQ: Set the issue to execute queue.\n");
issueToExecuteQueue = i2e_ptr;
}
template <class Impl>
void
InstructionQueue<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
{
DPRINTF(IQ, "IQ: Set the time buffer.\n");
timeBuffer = tb_ptr;
fromCommit = timeBuffer->getWire(-commitToIEWDelay);
}
template <class Impl>
unsigned
InstructionQueue<Impl>::numFreeEntries()
{
return freeEntries;
}
// Might want to do something more complex if it knows how many instructions
// will be issued this cycle.
template <class Impl>
bool
InstructionQueue<Impl>::isFull()
{
if (freeEntries == 0) {
return(true);
} else {
return(false);
}
}
template <class Impl>
void
InstructionQueue<Impl>::insert(DynInstPtr &new_inst)
{
// Make sure the instruction is valid
assert(new_inst);
DPRINTF(IQ, "IQ: Adding instruction PC %#x to the IQ.\n",
new_inst->readPC());
// Check if there are any free entries. Panic if there are none.
// Might want to have this return a fault in the future instead of
// panicing.
assert(freeEntries != 0);
// If the IQ currently has nothing in it, then there's a possibility
// that the tail iterator is invalid (might have been pointing at an
// instruction that was retired). Reset the tail iterator.
if (freeEntries == numEntries) {
tail = cpu->instList.begin();
}
// Move the tail iterator. Instructions may not have been issued
// to the IQ, so we may have to increment the iterator more than once.
while ((*tail) != new_inst) {
tail++;
// Make sure the tail iterator points at something legal.
assert(tail != cpu->instList.end());
}
// Decrease the number of free entries.
--freeEntries;
// Look through its source registers (physical regs), and mark any
// dependencies.
addToDependents(new_inst);
// Have this instruction set itself as the producer of its destination
// register(s).
createDependency(new_inst);
// If it's a memory instruction, add it to the memory dependency
// unit.
if (new_inst->isMemRef()) {
memDepUnit.insert(new_inst);
// Uh..forgot to look it up and put it on the proper dependency list
// if the instruction should not go yet.
} else {
// If the instruction is ready then add it to the ready list.
addIfReady(new_inst);
}
++iqInstsAdded;
assert(freeEntries == (numEntries - countInsts()));
}
template <class Impl>
void
InstructionQueue<Impl>::insertNonSpec(DynInstPtr &inst)
{
nonSpecInsts[inst->seqNum] = inst;
// @todo: Clean up this code; can do it by setting inst as unable
// to issue, then calling normal insert on the inst.
// Make sure the instruction is valid
assert(inst);
DPRINTF(IQ, "IQ: Adding instruction PC %#x to the IQ.\n",
inst->readPC());
// Check if there are any free entries. Panic if there are none.
// Might want to have this return a fault in the future instead of
// panicing.
assert(freeEntries != 0);
// If the IQ currently has nothing in it, then there's a possibility
// that the tail iterator is invalid (might have been pointing at an
// instruction that was retired). Reset the tail iterator.
if (freeEntries == numEntries) {
tail = cpu->instList.begin();
}
// Move the tail iterator. Instructions may not have been issued
// to the IQ, so we may have to increment the iterator more than once.
while ((*tail) != inst) {
tail++;
// Make sure the tail iterator points at something legal.
assert(tail != cpu->instList.end());
}
// Decrease the number of free entries.
--freeEntries;
// Have this instruction set itself as the producer of its destination
// register(s).
createDependency(inst);
// If it's a memory instruction, add it to the memory dependency
// unit.
if (inst->isMemRef()) {
memDepUnit.insertNonSpec(inst);
}
++iqNonSpecInstsAdded;
}
// Slightly hack function to advance the tail iterator in the case that
// the IEW stage issues an instruction that is not added to the IQ. This
// is needed in case a long chain of such instructions occurs.
// I don't think this is used anymore.
template <class Impl>
void
InstructionQueue<Impl>::advanceTail(DynInstPtr &inst)
{
// Make sure the instruction is valid
assert(inst);
DPRINTF(IQ, "IQ: Adding instruction PC %#x to the IQ.\n",
inst->readPC());
// Check if there are any free entries. Panic if there are none.
// Might want to have this return a fault in the future instead of
// panicing.
assert(freeEntries != 0);
// If the IQ currently has nothing in it, then there's a possibility
// that the tail iterator is invalid (might have been pointing at an
// instruction that was retired). Reset the tail iterator.
if (freeEntries == numEntries) {
tail = cpu->instList.begin();
}
// Move the tail iterator. Instructions may not have been issued
// to the IQ, so we may have to increment the iterator more than once.
while ((*tail) != inst) {
tail++;
// Make sure the tail iterator points at something legal.
assert(tail != cpu->instList.end());
}
assert(freeEntries <= numEntries);
// Have this instruction set itself as the producer of its destination
// register(s).
createDependency(inst);
}
// Need to make sure the number of float and integer instructions
// issued does not exceed the total issue bandwidth.
// @todo: Figure out a better way to remove the squashed items from the
// lists. Checking the top item of each list to see if it's squashed
// wastes time and forces jumps.
template <class Impl>
void
InstructionQueue<Impl>::scheduleReadyInsts()
{
DPRINTF(IQ, "IQ: Attempting to schedule ready instructions from "
"the IQ.\n");
int int_issued = 0;
int float_issued = 0;
int branch_issued = 0;
int memory_issued = 0;
int squashed_issued = 0;
int total_issued = 0;
IssueStruct *i2e_info = issueToExecuteQueue->access(0);
bool insts_available = !readyBranchInsts.empty() ||
!readyIntInsts.empty() ||
!readyFloatInsts.empty() ||
!memDepUnit.empty() ||
!readyMiscInsts.empty() ||
!squashedInsts.empty();
// Note: Requires a globally defined constant.
InstSeqNum oldest_inst = MaxInstSeqNum;
InstList list_with_oldest = None;
// Temporary values.
DynInstPtr int_head_inst;
DynInstPtr float_head_inst;
DynInstPtr branch_head_inst;
DynInstPtr mem_head_inst;
DynInstPtr misc_head_inst;
DynInstPtr squashed_head_inst;
// Somewhat nasty code to look at all of the lists where issuable
// instructions are located, and choose the oldest instruction among
// those lists. Consider a rewrite in the future.
while (insts_available && total_issued < totalWidth)
{
// Set this to false. Each if-block is required to set it to true
// if there were instructions available this check. This will cause
// this loop to run once more than necessary, but avoids extra calls.
insts_available = false;
oldest_inst = MaxInstSeqNum;
list_with_oldest = None;
if (!readyIntInsts.empty() &&
int_issued < intWidth) {
insts_available = true;
int_head_inst = readyIntInsts.top();
if (int_head_inst->isSquashed()) {
readyIntInsts.pop();
++iqLoopSquashStalls;
continue;
}
oldest_inst = int_head_inst->seqNum;
list_with_oldest = Int;
}
if (!readyFloatInsts.empty() &&
float_issued < floatWidth) {
insts_available = true;
float_head_inst = readyFloatInsts.top();
if (float_head_inst->isSquashed()) {
readyFloatInsts.pop();
++iqLoopSquashStalls;
continue;
} else if (float_head_inst->seqNum < oldest_inst) {
oldest_inst = float_head_inst->seqNum;
list_with_oldest = Float;
}
}
if (!readyBranchInsts.empty() &&
branch_issued < branchWidth) {
insts_available = true;
branch_head_inst = readyBranchInsts.top();
if (branch_head_inst->isSquashed()) {
readyBranchInsts.pop();
++iqLoopSquashStalls;
continue;
} else if (branch_head_inst->seqNum < oldest_inst) {
oldest_inst = branch_head_inst->seqNum;
list_with_oldest = Branch;
}
}
if (!memDepUnit.empty() &&
memory_issued < memoryWidth) {
insts_available = true;
mem_head_inst = memDepUnit.top();
if (mem_head_inst->isSquashed()) {
memDepUnit.pop();
++iqLoopSquashStalls;
continue;
} else if (mem_head_inst->seqNum < oldest_inst) {
oldest_inst = mem_head_inst->seqNum;
list_with_oldest = Memory;
}
}
if (!readyMiscInsts.empty()) {
insts_available = true;
misc_head_inst = readyMiscInsts.top();
if (misc_head_inst->isSquashed()) {
readyMiscInsts.pop();
++iqLoopSquashStalls;
continue;
} else if (misc_head_inst->seqNum < oldest_inst) {
oldest_inst = misc_head_inst->seqNum;
list_with_oldest = Misc;
}
}
if (!squashedInsts.empty()) {
insts_available = true;
squashed_head_inst = squashedInsts.top();
if (squashed_head_inst->seqNum < oldest_inst) {
list_with_oldest = Squashed;
}
}
DynInstPtr issuing_inst = NULL;
switch (list_with_oldest) {
case None:
DPRINTF(IQ, "IQ: Not able to schedule any instructions. Issuing "
"inst is %#x.\n", issuing_inst);
break;
case Int:
issuing_inst = int_head_inst;
readyIntInsts.pop();
++int_issued;
DPRINTF(IQ, "IQ: Issuing integer instruction PC %#x.\n",
issuing_inst->readPC());
break;
case Float:
issuing_inst = float_head_inst;
readyFloatInsts.pop();
++float_issued;
DPRINTF(IQ, "IQ: Issuing float instruction PC %#x.\n",
issuing_inst->readPC());
break;
case Branch:
issuing_inst = branch_head_inst;
readyBranchInsts.pop();
++branch_issued;
DPRINTF(IQ, "IQ: Issuing branch instruction PC %#x.\n",
issuing_inst->readPC());
break;
case Memory:
issuing_inst = mem_head_inst;
memDepUnit.pop();
++memory_issued;
DPRINTF(IQ, "IQ: Issuing memory instruction PC %#x.\n",
issuing_inst->readPC());
break;
case Misc:
issuing_inst = misc_head_inst;
readyMiscInsts.pop();
++iqMiscInstsIssued;
DPRINTF(IQ, "IQ: Issuing a miscellaneous instruction PC %#x.\n",
issuing_inst->readPC());
break;
case Squashed:
assert(0 && "Squashed insts should not issue any more!");
squashedInsts.pop();
// Set the squashed instruction as able to commit so that commit
// can just drop it from the ROB. This is a bit faked.
++squashed_issued;
++freeEntries;
DPRINTF(IQ, "IQ: Issuing squashed instruction PC %#x.\n",
squashed_head_inst->readPC());
break;
}
if (list_with_oldest != None && list_with_oldest != Squashed) {
i2e_info->insts[total_issued] = issuing_inst;
i2e_info->size++;
issuing_inst->setIssued();
++freeEntries;
++total_issued;
}
assert(freeEntries == (numEntries - countInsts()));
}
iqIntInstsIssued += int_issued;
iqFloatInstsIssued += float_issued;
iqBranchInstsIssued += branch_issued;
iqMemInstsIssued += memory_issued;
iqSquashedInstsIssued += squashed_issued;
}
template <class Impl>
void
InstructionQueue<Impl>::scheduleNonSpec(const InstSeqNum &inst)
{
DPRINTF(IQ, "IQ: Marking nonspeculative instruction with sequence "
"number %i as ready to execute.\n", inst);
non_spec_it_t inst_it = nonSpecInsts.find(inst);
assert(inst_it != nonSpecInsts.end());
// Mark this instruction as ready to issue.
(*inst_it).second->setCanIssue();
// Now schedule the instruction.
if (!(*inst_it).second->isMemRef()) {
addIfReady((*inst_it).second);
} else {
memDepUnit.nonSpecInstReady((*inst_it).second);
}
nonSpecInsts.erase(inst_it);
}
template <class Impl>
void
InstructionQueue<Impl>::wakeDependents(DynInstPtr &completed_inst)
{
DPRINTF(IQ, "IQ: Waking dependents of completed instruction.\n");
//Look at the physical destination register of the DynInst
//and look it up on the dependency graph. Then mark as ready
//any instructions within the instruction queue.
DependencyEntry *curr;
// Tell the memory dependence unit to wake any dependents on this
// instruction if it is a memory instruction.
if (completed_inst->isMemRef()) {
memDepUnit.wakeDependents(completed_inst);
}
for (int dest_reg_idx = 0;
dest_reg_idx < completed_inst->numDestRegs();
dest_reg_idx++)
{
PhysRegIndex dest_reg =
completed_inst->renamedDestRegIdx(dest_reg_idx);
// Special case of uniq or control registers. They are not
// handled by the IQ and thus have no dependency graph entry.
// @todo Figure out a cleaner way to handle this.
if (dest_reg >= numPhysRegs) {
continue;
}
DPRINTF(IQ, "IQ: Waking any dependents on register %i.\n",
(int) dest_reg);
//Maybe abstract this part into a function.
//Go through the dependency chain, marking the registers as ready
//within the waiting instructions.
while (dependGraph[dest_reg].next) {
curr = dependGraph[dest_reg].next;
DPRINTF(IQ, "IQ: Waking up a dependent instruction, PC%#x.\n",
curr->inst->readPC());
// Might want to give more information to the instruction
// so that it knows which of its source registers is ready.
// However that would mean that the dependency graph entries
// would need to hold the src_reg_idx.
curr->inst->markSrcRegReady();
addIfReady(curr->inst);
dependGraph[dest_reg].next = curr->next;
DependencyEntry::mem_alloc_counter--;
curr->inst = NULL;
delete curr;
}
// Reset the head node now that all of its dependents have been woken
// up.
dependGraph[dest_reg].next = NULL;
dependGraph[dest_reg].inst = NULL;
// Mark the scoreboard as having that register ready.
regScoreboard[dest_reg] = true;
}
}
template <class Impl>
void
InstructionQueue<Impl>::violation(DynInstPtr &store,
DynInstPtr &faulting_load)
{
memDepUnit.violation(store, faulting_load);
}
template <class Impl>
void
InstructionQueue<Impl>::squash()
{
DPRINTF(IQ, "IQ: Starting to squash instructions in the IQ.\n");
// Read instruction sequence number of last instruction out of the
// time buffer.
squashedSeqNum = fromCommit->commitInfo.doneSeqNum;
// Setup the squash iterator to point to the tail.
squashIt = tail;
// Call doSquash if there are insts in the IQ
if (freeEntries != numEntries) {
doSquash();
}
// Also tell the memory dependence unit to squash.
memDepUnit.squash(squashedSeqNum);
}
template <class Impl>
void
InstructionQueue<Impl>::doSquash()
{
// Make sure the squash iterator isn't pointing to nothing.
assert(squashIt != cpu->instList.end());
// Make sure the squashed sequence number is valid.
assert(squashedSeqNum != 0);
DPRINTF(IQ, "IQ: Squashing instructions in the IQ.\n");
// Squash any instructions younger than the squashed sequence number
// given.
while ((*squashIt)->seqNum > squashedSeqNum) {
DynInstPtr squashed_inst = (*squashIt);
// Only handle the instruction if it actually is in the IQ and
// hasn't already been squashed in the IQ.
if (!squashed_inst->isIssued() &&
!squashed_inst->isSquashedInIQ()) {
// Remove the instruction from the dependency list.
// Hack for now: These below don't add themselves to the
// dependency list, so don't try to remove them.
if (!squashed_inst->isNonSpeculative()/* &&
!squashed_inst->isStore()*/
) {
for (int src_reg_idx = 0;
src_reg_idx < squashed_inst->numSrcRegs();
src_reg_idx++)
{
PhysRegIndex src_reg =
squashed_inst->renamedSrcRegIdx(src_reg_idx);
// Only remove it from the dependency graph if it was
// placed there in the first place.
// HACK: This assumes that instructions woken up from the
// dependency chain aren't informed that a specific src
// register has become ready. This may not always be true
// in the future.
if (!squashed_inst->isReadySrcRegIdx(src_reg_idx) &&
src_reg < numPhysRegs) {
dependGraph[src_reg].remove(squashed_inst);
}
++iqSquashedOperandsExamined;
}
// Might want to remove producers as well.
} else {
nonSpecInsts[squashed_inst->seqNum] = NULL;
nonSpecInsts.erase(squashed_inst->seqNum);
++iqSquashedNonSpecRemoved;
}
// Might want to also clear out the head of the dependency graph.
// Mark it as squashed within the IQ.
squashed_inst->setSquashedInIQ();
// squashedInsts.push(squashed_inst);
squashed_inst->setIssued();
squashed_inst->setCanCommit();
++freeEntries;
DPRINTF(IQ, "IQ: Instruction PC %#x squashed.\n",
squashed_inst->readPC());
}
--squashIt;
++iqSquashedInstsExamined;
}
assert(freeEntries <= numEntries);
if (freeEntries == numEntries) {
tail = cpu->instList.end();
}
}
template <class Impl>
void
InstructionQueue<Impl>::stopSquash()
{
// Clear up the squash variables to ensure that squashing doesn't
// get called improperly.
squashedSeqNum = 0;
squashIt = cpu->instList.end();
}
template <class Impl>
void
InstructionQueue<Impl>::DependencyEntry::insert(DynInstPtr &new_inst)
{
//Add this new, dependent instruction at the head of the dependency
//chain.
// First create the entry that will be added to the head of the
// dependency chain.
DependencyEntry *new_entry = new DependencyEntry;
new_entry->next = this->next;
new_entry->inst = new_inst;
// Then actually add it to the chain.
this->next = new_entry;
++mem_alloc_counter;
}
template <class Impl>
void
InstructionQueue<Impl>::DependencyEntry::remove(DynInstPtr &inst_to_remove)
{
DependencyEntry *prev = this;
DependencyEntry *curr = this->next;
// Make sure curr isn't NULL. Because this instruction is being
// removed from a dependency list, it must have been placed there at
// an earlier time. The dependency chain should not be empty,
// unless the instruction dependent upon it is already ready.
if (curr == NULL) {
return;
}
// Find the instruction to remove within the dependency linked list.
while(curr->inst != inst_to_remove)
{
prev = curr;
curr = curr->next;
assert(curr != NULL);
}
// Now remove this instruction from the list.
prev->next = curr->next;
--mem_alloc_counter;
// Could push this off to the destructor of DependencyEntry
curr->inst = NULL;
delete curr;
}
template <class Impl>
bool
InstructionQueue<Impl>::addToDependents(DynInstPtr &new_inst)
{
// Loop through the instruction's source registers, adding
// them to the dependency list if they are not ready.
int8_t total_src_regs = new_inst->numSrcRegs();
bool return_val = false;
for (int src_reg_idx = 0;
src_reg_idx < total_src_regs;
src_reg_idx++)
{
// Only add it to the dependency graph if it's not ready.
if (!new_inst->isReadySrcRegIdx(src_reg_idx)) {
PhysRegIndex src_reg = new_inst->renamedSrcRegIdx(src_reg_idx);
// Check the IQ's scoreboard to make sure the register
// hasn't become ready while the instruction was in flight
// between stages. Only if it really isn't ready should
// it be added to the dependency graph.
if (src_reg >= numPhysRegs) {
continue;
} else if (regScoreboard[src_reg] == false) {
DPRINTF(IQ, "IQ: Instruction PC %#x has src reg %i that "
"is being added to the dependency chain.\n",
new_inst->readPC(), src_reg);
dependGraph[src_reg].insert(new_inst);
// Change the return value to indicate that something
// was added to the dependency graph.
return_val = true;
} else {
DPRINTF(IQ, "IQ: Instruction PC %#x has src reg %i that "
"became ready before it reached the IQ.\n",
new_inst->readPC(), src_reg);
// Mark a register ready within the instruction.
new_inst->markSrcRegReady();
}
}
}
return return_val;
}
template <class Impl>
void
InstructionQueue<Impl>::createDependency(DynInstPtr &new_inst)
{
//Actually nothing really needs to be marked when an
//instruction becomes the producer of a register's value,
//but for convenience a ptr to the producing instruction will
//be placed in the head node of the dependency links.
int8_t total_dest_regs = new_inst->numDestRegs();
for (int dest_reg_idx = 0;
dest_reg_idx < total_dest_regs;
dest_reg_idx++)
{
PhysRegIndex dest_reg = new_inst->renamedDestRegIdx(dest_reg_idx);
// Instructions that use the misc regs will have a reg number
// higher than the normal physical registers. In this case these
// registers are not renamed, and there is no need to track
// dependencies as these instructions must be executed at commit.
if (dest_reg >= numPhysRegs) {
continue;
}
dependGraph[dest_reg].inst = new_inst;
if (dependGraph[dest_reg].next) {
dumpDependGraph();
panic("IQ: Dependency graph not empty!");
}
// Mark the scoreboard to say it's not yet ready.
regScoreboard[dest_reg] = false;
}
}
template <class Impl>
void
InstructionQueue<Impl>::addIfReady(DynInstPtr &inst)
{
//If the instruction now has all of its source registers
// available, then add it to the list of ready instructions.
if (inst->readyToIssue()) {
//Add the instruction to the proper ready list.
if (inst->isControl()) {
DPRINTF(IQ, "IQ: Branch instruction is ready to issue, "
"putting it onto the ready list, PC %#x.\n",
inst->readPC());
readyBranchInsts.push(inst);
} else if (inst->isMemRef()) {
DPRINTF(IQ, "IQ: Checking if memory instruction can issue.\n");
// Message to the mem dependence unit that this instruction has
// its registers ready.
memDepUnit.regsReady(inst);
#if 0
if (memDepUnit.readyToIssue(inst)) {
DPRINTF(IQ, "IQ: Memory instruction is ready to issue, "
"putting it onto the ready list, PC %#x.\n",
inst->readPC());
readyMemInsts.push(inst);
} else {
// Make dependent on the store.
// Will need some way to get the store instruction it should
// be dependent upon; then when the store issues it can
// put the instruction on the ready list.
// Yet another tree?
assert(0 && "Instruction has no way to actually issue");
}
#endif
} else if (inst->isInteger()) {
DPRINTF(IQ, "IQ: Integer instruction is ready to issue, "
"putting it onto the ready list, PC %#x.\n",
inst->readPC());
readyIntInsts.push(inst);
} else if (inst->isFloating()) {
DPRINTF(IQ, "IQ: Floating instruction is ready to issue, "
"putting it onto the ready list, PC %#x.\n",
inst->readPC());
readyFloatInsts.push(inst);
} else {
DPRINTF(IQ, "IQ: Miscellaneous instruction is ready to issue, "
"putting it onto the ready list, PC %#x..\n",
inst->readPC());
readyMiscInsts.push(inst);
}
}
}
/*
* Caution, this function must not be called prior to tail being updated at
* least once, otherwise it will fail the assertion. This is because
* instList.begin() actually changes upon the insertion of an element into the
* list when the list is empty.
*/
template <class Impl>
int
InstructionQueue<Impl>::countInsts()
{
ListIt count_it = cpu->instList.begin();
int total_insts = 0;
if (tail == cpu->instList.end())
return 0;
while (count_it != tail) {
if (!(*count_it)->isIssued()) {
++total_insts;
}
++count_it;
assert(count_it != cpu->instList.end());
}
// Need to count the tail iterator as well.
if (count_it != cpu->instList.end() &&
(*count_it) &&
!(*count_it)->isIssued()) {
++total_insts;
}
return total_insts;
}
template <class Impl>
void
InstructionQueue<Impl>::dumpDependGraph()
{
DependencyEntry *curr;
for (int i = 0; i < numPhysRegs; ++i)
{
curr = &dependGraph[i];
if (curr->inst) {
cprintf("dependGraph[%i]: producer: %#x consumer: ", i,
curr->inst->readPC());
} else {
cprintf("dependGraph[%i]: No producer. consumer: ", i);
}
while (curr->next != NULL) {
curr = curr->next;
cprintf("%#x ", curr->inst->readPC());
}
cprintf("\n");
}
}
template <class Impl>
void
InstructionQueue<Impl>::dumpLists()
{
cprintf("Ready integer list size: %i\n", readyIntInsts.size());
cprintf("Ready float list size: %i\n", readyFloatInsts.size());
cprintf("Ready branch list size: %i\n", readyBranchInsts.size());
cprintf("Ready misc list size: %i\n", readyMiscInsts.size());
cprintf("Squashed list size: %i\n", squashedInsts.size());
cprintf("Non speculative list size: %i\n", nonSpecInsts.size());
non_spec_it_t non_spec_it = nonSpecInsts.begin();
cprintf("Non speculative list: ");
while (non_spec_it != nonSpecInsts.end()) {
cprintf("%#x ", (*non_spec_it).second->readPC());
++non_spec_it;
}
cprintf("\n");
}