llvm/lib/Target/TargetSchedInfo.cpp
2004-02-29 06:31:16 +00:00

256 lines
8.7 KiB
C++

//===-- SchedInfo.cpp - Generic code to support target schedulers ----------==//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the generic part of a Scheduler description for a
// target. This functionality is defined in the llvm/Target/SchedInfo.h file.
//
//===----------------------------------------------------------------------===//
#include "llvm/Target/TargetSchedInfo.h"
#include "llvm/Target/TargetMachine.h"
namespace llvm {
resourceId_t MachineResource::nextId = 0;
// Check if fromRVec and toRVec have *any* common entries.
// Assume the vectors are sorted in increasing order.
// Algorithm copied from function set_intersection() for sorted ranges
// (stl_algo.h).
//
inline static bool
RUConflict(const std::vector<resourceId_t>& fromRVec,
const std::vector<resourceId_t>& toRVec)
{
unsigned fN = fromRVec.size(), tN = toRVec.size();
unsigned fi = 0, ti = 0;
while (fi < fN && ti < tN) {
if (fromRVec[fi] < toRVec[ti])
++fi;
else if (toRVec[ti] < fromRVec[fi])
++ti;
else
return true;
}
return false;
}
static cycles_t
ComputeMinGap(const InstrRUsage &fromRU,
const InstrRUsage &toRU)
{
cycles_t minGap = 0;
if (fromRU.numBubbles > 0)
minGap = fromRU.numBubbles;
if (minGap < fromRU.numCycles) {
// only need to check from cycle `minGap' onwards
for (cycles_t gap=minGap; gap <= fromRU.numCycles-1; gap++) {
// check if instr. #2 can start executing `gap' cycles after #1
// by checking for resource conflicts in each overlapping cycle
cycles_t numOverlap =std::min(fromRU.numCycles - gap, toRU.numCycles);
for (cycles_t c = 0; c <= numOverlap-1; c++)
if (RUConflict(fromRU.resourcesByCycle[gap + c],
toRU.resourcesByCycle[c])) {
// conflict found so minGap must be more than `gap'
minGap = gap+1;
break;
}
}
}
return minGap;
}
//---------------------------------------------------------------------------
// class TargetSchedInfo
// Interface to machine description for instruction scheduling
//---------------------------------------------------------------------------
TargetSchedInfo::TargetSchedInfo(const TargetMachine& tgt,
int NumSchedClasses,
const InstrClassRUsage* ClassRUsages,
const InstrRUsageDelta* UsageDeltas,
const InstrIssueDelta* IssueDeltas,
unsigned NumUsageDeltas,
unsigned NumIssueDeltas)
: target(tgt),
numSchedClasses(NumSchedClasses), mii(& tgt.getInstrInfo()),
classRUsages(ClassRUsages), usageDeltas(UsageDeltas),
issueDeltas(IssueDeltas), numUsageDeltas(NumUsageDeltas),
numIssueDeltas(NumIssueDeltas)
{}
void
TargetSchedInfo::initializeResources()
{
assert(MAX_NUM_SLOTS >= (int)getMaxNumIssueTotal()
&& "Insufficient slots for static data! Increase MAX_NUM_SLOTS");
// First, compute common resource usage info for each class because
// most instructions will probably behave the same as their class.
// Cannot allocate a vector of InstrRUsage so new each one.
//
std::vector<InstrRUsage> instrRUForClasses;
instrRUForClasses.resize(numSchedClasses);
for (InstrSchedClass sc = 0; sc < numSchedClasses; sc++) {
// instrRUForClasses.push_back(new InstrRUsage);
instrRUForClasses[sc].setMaxSlots(getMaxNumIssueTotal());
instrRUForClasses[sc].setTo(classRUsages[sc]);
}
computeInstrResources(instrRUForClasses);
computeIssueGaps(instrRUForClasses);
}
void
TargetSchedInfo::computeInstrResources(const std::vector<InstrRUsage>&
instrRUForClasses)
{
int numOpCodes = mii->getNumOpcodes();
instrRUsages.resize(numOpCodes);
// First get the resource usage information from the class resource usages.
for (MachineOpCode op = 0; op < numOpCodes; ++op) {
InstrSchedClass sc = getSchedClass(op);
assert(sc < numSchedClasses);
instrRUsages[op] = instrRUForClasses[sc];
}
// Now, modify the resource usages as specified in the deltas.
for (unsigned i = 0; i < numUsageDeltas; ++i) {
MachineOpCode op = usageDeltas[i].opCode;
assert(op < numOpCodes);
instrRUsages[op].addUsageDelta(usageDeltas[i]);
}
// Then modify the issue restrictions as specified in the deltas.
for (unsigned i = 0; i < numIssueDeltas; ++i) {
MachineOpCode op = issueDeltas[i].opCode;
assert(op < numOpCodes);
instrRUsages[issueDeltas[i].opCode].addIssueDelta(issueDeltas[i]);
}
}
void
TargetSchedInfo::computeIssueGaps(const std::vector<InstrRUsage>&
instrRUForClasses)
{
int numOpCodes = mii->getNumOpcodes();
issueGaps.resize(numOpCodes);
conflictLists.resize(numOpCodes);
assert(numOpCodes < (1 << MAX_OPCODE_SIZE) - 1
&& "numOpCodes invalid for implementation of class OpCodePair!");
// First, compute issue gaps between pairs of classes based on common
// resources usages for each class, because most instruction pairs will
// usually behave the same as their class.
//
int classPairGaps[numSchedClasses][numSchedClasses];
for (InstrSchedClass fromSC=0; fromSC < numSchedClasses; fromSC++)
for (InstrSchedClass toSC=0; toSC < numSchedClasses; toSC++) {
int classPairGap = ComputeMinGap(instrRUForClasses[fromSC],
instrRUForClasses[toSC]);
classPairGaps[fromSC][toSC] = classPairGap;
}
// Now, for each pair of instructions, use the class pair gap if both
// instructions have identical resource usage as their respective classes.
// If not, recompute the gap for the pair from scratch.
longestIssueConflict = 0;
for (MachineOpCode fromOp=0; fromOp < numOpCodes; fromOp++)
for (MachineOpCode toOp=0; toOp < numOpCodes; toOp++) {
int instrPairGap =
(instrRUsages[fromOp].sameAsClass && instrRUsages[toOp].sameAsClass)
? classPairGaps[getSchedClass(fromOp)][getSchedClass(toOp)]
: ComputeMinGap(instrRUsages[fromOp], instrRUsages[toOp]);
if (instrPairGap > 0) {
this->setGap(instrPairGap, fromOp, toOp);
conflictLists[fromOp].push_back(toOp);
longestIssueConflict=std::max(longestIssueConflict, instrPairGap);
}
}
}
void InstrRUsage::setTo(const InstrClassRUsage& classRU) {
sameAsClass = true;
isSingleIssue = classRU.isSingleIssue;
breaksGroup = classRU.breaksGroup;
numBubbles = classRU.numBubbles;
for (unsigned i=0; i < classRU.numSlots; i++) {
unsigned slot = classRU.feasibleSlots[i];
assert(slot < feasibleSlots.size() && "Invalid slot specified!");
this->feasibleSlots[slot] = true;
}
numCycles = classRU.totCycles;
resourcesByCycle.resize(this->numCycles);
for (unsigned i=0; i < classRU.numRUEntries; i++)
for (unsigned c=classRU.V[i].startCycle, NC = c + classRU.V[i].numCycles;
c < NC; c++)
this->resourcesByCycle[c].push_back(classRU.V[i].resourceId);
// Sort each resource usage vector by resourceId_t to speed up conflict
// checking
for (unsigned i=0; i < this->resourcesByCycle.size(); i++)
sort(resourcesByCycle[i].begin(), resourcesByCycle[i].end());
}
// Add the extra resource usage requirements specified in the delta.
// Note that a negative value of `numCycles' means one entry for that
// resource should be deleted for each cycle.
//
void InstrRUsage::addUsageDelta(const InstrRUsageDelta &delta) {
int NC = delta.numCycles;
sameAsClass = false;
// resize the resources vector if more cycles are specified
unsigned maxCycles = this->numCycles;
maxCycles = std::max(maxCycles, delta.startCycle + abs(NC) - 1);
if (maxCycles > this->numCycles) {
this->resourcesByCycle.resize(maxCycles);
this->numCycles = maxCycles;
}
if (NC >= 0)
for (unsigned c=delta.startCycle, last=c+NC-1; c <= last; c++)
this->resourcesByCycle[c].push_back(delta.resourceId);
else
// Remove the resource from all NC cycles.
for (unsigned c=delta.startCycle, last=(c-NC)-1; c <= last; c++) {
// Look for the resource backwards so we remove the last entry
// for that resource in each cycle.
std::vector<resourceId_t>& rvec = this->resourcesByCycle[c];
int r;
for (r = rvec.size() - 1; r >= 0; r--)
if (rvec[r] == delta.resourceId) {
// found last entry for the resource
rvec.erase(rvec.begin() + r);
break;
}
assert(r >= 0 && "Resource to remove was unused in cycle c!");
}
}
} // End llvm namespace