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MachineScheduler: Remember top/bottom choice in bidirectional scheduling

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Remember the last choice for the top/bottom scheduling boundary in
bidirectional scheduling mode. The top choice should not change if we
schedule at the bottom and vice versa.

This allows us to improve compiletime: We only recalculate the best pick
for one border and re-use the cached top-pick from the other border.

Differential Revision: http://reviews.llvm.org/D19350

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273766 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matthias Braun 2016-06-25 02:03:36 +00:00
parent 16fa6f1061
commit 2feb69ebcd
2 changed files with 77 additions and 11 deletions
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29
include/llvm/CodeGen/MachineScheduler.h
View File

@ -779,6 +779,15 @@ public:
unsigned DemandResIdx;
CandPolicy(): ReduceLatency(false), ReduceResIdx(0), DemandResIdx(0) {}
bool operator==(const CandPolicy &RHS) const {
return ReduceLatency == RHS.ReduceLatency &&
ReduceResIdx == RHS.ReduceResIdx &&
DemandResIdx == RHS.DemandResIdx;
}
bool operator!=(const CandPolicy &RHS) const {
return !(*this == RHS);
}
};
/// Status of an instruction's critical resource consumption.
@ -820,8 +829,17 @@ public:
// Critical resource consumption of the best candidate.
SchedResourceDelta ResDelta;
SchedCandidate(const CandPolicy &policy)
: Policy(policy), SU(nullptr), Reason(NoCand), AtTop(false) {}
SchedCandidate() { reset(CandPolicy()); }
SchedCandidate(const CandPolicy &Policy) { reset(Policy); }
void reset(const CandPolicy &NewPolicy) {
Policy = NewPolicy;
SU = nullptr;
Reason = NoCand;
AtTop = false;
RPDelta = RegPressureDelta();
ResDelta = SchedResourceDelta();
}
bool isValid() const { return SU; }
@ -866,6 +884,11 @@ class GenericScheduler : public GenericSchedulerBase {
SchedBoundary Top;
SchedBoundary Bot;
/// Candidate last picked from Top boundary.
SchedCandidate TopCand;
/// Candidate last picked from Bot boundary.
SchedCandidate BotCand;
MachineSchedPolicy RegionPolicy;
public:
GenericScheduler(const MachineSchedContext *C):
@ -894,10 +917,12 @@ public:
void releaseTopNode(SUnit *SU) override {
Top.releaseTopNode(SU);
TopCand.SU = nullptr;
}
void releaseBottomNode(SUnit *SU) override {
Bot.releaseBottomNode(SU);
BotCand.SU = nullptr;
}
void registerRoots() override;

59
lib/CodeGen/MachineScheduler.cpp
View File

@ -2557,6 +2557,8 @@ void GenericScheduler::initialize(ScheduleDAGMI *dag) {
DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer(
Itin, DAG);
}
TopCand.SU = nullptr;
BotCand.SU = nullptr;
}
/// Initialize the per-region scheduling policy.
@ -2954,17 +2956,56 @@ SUnit *GenericScheduler::pickNodeBidirectional(bool &IsTopNode) {
CandPolicy TopPolicy;
setPolicy(TopPolicy, /*IsPostRA=*/false, Top, &Bot);
// Prefer bottom scheduling when heuristics are silent.
CandPolicy NoPolicy;
SchedCandidate Cand(NoPolicy);
// See if BotCand is still valid (because we previously scheduled from Top).
DEBUG(dbgs() << "Picking from Bot:\n");
pickNodeFromQueue(Bot, BotPolicy, DAG->getBotRPTracker(), Cand);
assert(Cand.Reason != NoCand && "failed to find the first candidate");
if (!BotCand.isValid() || BotCand.SU->isScheduled ||
BotCand.Policy != BotPolicy) {
BotCand.reset(CandPolicy());
pickNodeFromQueue(Bot, BotPolicy, DAG->getBotRPTracker(), BotCand);
assert(BotCand.Reason != NoCand && "failed to find the first candidate");
} else {
DEBUG(traceCandidate(BotCand));
#ifndef NDEBUG
if (VerifyScheduling) {
SchedCandidate TCand;
TCand.reset(CandPolicy());
pickNodeFromQueue(Bot, BotPolicy, DAG->getBotRPTracker(), TCand);
assert(TCand.SU == BotCand.SU &&
"Last pick result should correspond to re-picking right now");
}
#endif
}
// Check if the top Q has a better candidate.
DEBUG(dbgs() << "Picking from Top:\n");
pickNodeFromQueue(Top, TopPolicy, DAG->getTopRPTracker(), Cand);
assert(Cand.Reason != NoCand && "failed to find the first candidate");
if (!TopCand.isValid() || TopCand.SU->isScheduled ||
TopCand.Policy != TopPolicy) {
TopCand.reset(CandPolicy());
pickNodeFromQueue(Top, TopPolicy, DAG->getTopRPTracker(), TopCand);
assert(TopCand.Reason != NoCand && "failed to find the first candidate");
} else {
DEBUG(traceCandidate(TopCand));
#ifndef NDEBUG
if (VerifyScheduling) {
SchedCandidate TCand;
TCand.reset(CandPolicy());
pickNodeFromQueue(Top, TopPolicy, DAG->getTopRPTracker(), TCand);
assert(TCand.SU == TopCand.SU &&
"Last pick result should correspond to re-picking right now");
}
#endif
}
// Pick best from BotCand and TopCand.
assert(BotCand.isValid());
assert(TopCand.isValid());
SchedCandidate Cand = BotCand;
TopCand.Reason = NoCand;
tryCandidate(Cand, TopCand, nullptr);
if (TopCand.Reason != NoCand) {
Cand.setBest(TopCand);
DEBUG(traceCandidate(Cand));
}
IsTopNode = Cand.AtTop;
tracePick(Cand);
@ -2984,7 +3025,7 @@ SUnit *GenericScheduler::pickNode(bool &IsTopNode) {
SU = Top.pickOnlyChoice();
if (!SU) {
CandPolicy NoPolicy;
SchedCandidate TopCand(NoPolicy);
TopCand.reset(NoPolicy);
pickNodeFromQueue(Top, NoPolicy, DAG->getTopRPTracker(), TopCand);
assert(TopCand.Reason != NoCand && "failed to find a candidate");
tracePick(TopCand);
@ -2995,7 +3036,7 @@ SUnit *GenericScheduler::pickNode(bool &IsTopNode) {
SU = Bot.pickOnlyChoice();
if (!SU) {
CandPolicy NoPolicy;
SchedCandidate BotCand(NoPolicy);
BotCand.reset(NoPolicy);
pickNodeFromQueue(Bot, NoPolicy, DAG->getBotRPTracker(), BotCand);
assert(BotCand.Reason != NoCand && "failed to find a candidate");
tracePick(BotCand);