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misched: avoid scheduling instructions that can't be dispatched.

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llvm-svn: 159408
This commit is contained in:
Andrew Trick 2012-06-29 03:23:24 +00:00
parent bcf581b08c
commit f990c5c8ba
1 changed files with 29 additions and 6 deletions
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35
lib/CodeGen/MachineScheduler.cpp
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@ -824,6 +824,8 @@ class ConvergingScheduler : public MachineSchedStrategy {
return Available.getID() == ConvergingScheduler::TopQID;
}
bool checkHazard(SUnit *SU);
void releaseNode(SUnit *SU, unsigned ReadyCycle);
void bumpCycle();
@ -932,6 +934,29 @@ void ConvergingScheduler::releaseBottomNode(SUnit *SU) {
Bot.releaseNode(SU, SU->BotReadyCycle);
}
/// Does this SU have a hazard within the current instruction group.
///
/// The scheduler supports two modes of hazard recognition. The first is the
/// ScheduleHazardRecognizer API. It is a fully general hazard recognizer that
/// supports highly complicated in-order reservation tables
/// (ScoreboardHazardRecognizer) and arbitraty target-specific logic.
///
/// The second is a streamlined mechanism that checks for hazards based on
/// simple counters that the scheduler itself maintains. It explicitly checks
/// for instruction dispatch limitations, including the number of micro-ops that
/// can dispatch per cycle.
///
/// TODO: Also check whether the SU must start a new group.
bool ConvergingScheduler::SchedBoundary::checkHazard(SUnit *SU) {
if (HazardRec->isEnabled())
return HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard;
if (IssueCount + DAG->getNumMicroOps(SU->getInstr()) > DAG->getIssueWidth())
return true;
return false;
}
void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU,
unsigned ReadyCycle) {
if (ReadyCycle < MinReadyCycle)
@ -939,9 +964,7 @@ void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU,
// Check for interlocks first. For the purpose of other heuristics, an
// instruction that cannot issue appears as if it's not in the ReadyQueue.
if (ReadyCycle > CurrCycle
|| (HazardRec->isEnabled() && (HazardRec->getHazardType(SU)
!= ScheduleHazardRecognizer::NoHazard)))
if (ReadyCycle > CurrCycle || checkHazard(SU))
Pending.push(SU);
else
Available.push(SU);
@ -985,7 +1008,8 @@ void ConvergingScheduler::SchedBoundary::bumpNode(SUnit *SU) {
}
HazardRec->EmitInstruction(SU);
}
// Check the instruction group size limit.
// Check the instruction group dispatch limit.
// TODO: Check if this SU must end a dispatch group.
IssueCount += DAG->getNumMicroOps(SU->getInstr());
if (IssueCount >= DAG->getIssueWidth()) {
DEBUG(dbgs() << "*** Max instrs at cycle " << CurrCycle << '\n');
@ -1012,8 +1036,7 @@ void ConvergingScheduler::SchedBoundary::releasePending() {
if (ReadyCycle > CurrCycle)
continue;
if (HazardRec->isEnabled()
&& HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard)
if (checkHazard(SU))
continue;
Available.push(SU);