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Added -misched-regpressure option.

Browse Source 
Register pressure tracking is half the complexity of the
scheduler. It's useful to be able to turn it off for compile time and
performance comparisons.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189987 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2013-09-04 20:59:59 +00:00
parent b4b7a52ec5
commit 42ebb3ad41
4 changed files with 57 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/llvm/CodeGen/MachineScheduler.h
View File

@ -227,6 +227,7 @@ protected:
PressureDiffs SUPressureDiffs;
/// Register pressure in this region computed by initRegPressure.
bool ShouldTrackPressure;
IntervalPressure RegPressure;
RegPressureTracker RPTracker;
@ -259,8 +260,9 @@ public:
ScheduleDAGMI(MachineSchedContext *C, MachineSchedStrategy *S):
ScheduleDAGInstrs(*C->MF, *C->MLI, *C->MDT, /*IsPostRA=*/false, C->LIS),
AA(C->AA), RegClassInfo(C->RegClassInfo), SchedImpl(S), DFSResult(0),
Topo(SUnits, &ExitSU), RPTracker(RegPressure), CurrentTop(),
TopRPTracker(TopPressure), CurrentBottom(), BotRPTracker(BotPressure),
Topo(SUnits, &ExitSU), ShouldTrackPressure(false),
RPTracker(RegPressure), CurrentTop(), TopRPTracker(TopPressure),
CurrentBottom(), BotRPTracker(BotPressure),
NextClusterPred(NULL), NextClusterSucc(NULL) {
#ifndef NDEBUG
NumInstrsScheduled = 0;

2
include/llvm/CodeGen/RegisterPressure.h
View File

@ -288,6 +288,8 @@ public:
MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(false),
TrackUntiedDefs(false) {}
void reset();
void init(const MachineFunction *mf, const RegisterClassInfo *rci,
const LiveIntervals *lis, const MachineBasicBlock *mbb,
MachineBasicBlock::const_iterator pos,

44
lib/CodeGen/MachineScheduler.cpp
View File

@ -53,6 +53,9 @@ static cl::opt<unsigned> MISchedCutoff("misched-cutoff", cl::Hidden,
static bool ViewMISchedDAGs = false;
#endif // NDEBUG
static cl::opt<bool> EnableRegPressure("misched-regpressure", cl::Hidden,
cl::desc("Enable register pressure scheduling."), cl::init(true));
static cl::opt<bool> EnableCyclicPath("misched-cyclicpath", cl::Hidden,
cl::desc("Enable cyclic critical path analysis."), cl::init(false));
@ -477,6 +480,8 @@ void ScheduleDAGMI::enterRegion(MachineBasicBlock *bb,
{
ScheduleDAGInstrs::enterRegion(bb, begin, end, regioninstrs);
ShouldTrackPressure = EnableRegPressure;
// For convenience remember the end of the liveness region.
LiveRegionEnd =
(RegionEnd == bb->end()) ? RegionEnd : llvm::next(RegionEnd);
@ -657,6 +662,13 @@ void ScheduleDAGMI::schedule() {
/// Build the DAG and setup three register pressure trackers.
void ScheduleDAGMI::buildDAGWithRegPressure() {
if (!ShouldTrackPressure) {
RPTracker.reset();
RegionCriticalPSets.clear();
buildSchedGraph(AA);
return;
}
// Initialize the register pressure tracker used by buildSchedGraph.
RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd,
/*TrackUntiedDefs=*/true);
@ -820,11 +832,13 @@ void ScheduleDAGMI::initQueues(ArrayRef<SUnit*> TopRoots,
SchedImpl->registerRoots();
// Advance past initial DebugValues.
assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker");
CurrentTop = nextIfDebug(RegionBegin, RegionEnd);
TopRPTracker.setPos(CurrentTop);
CurrentBottom = RegionEnd;
if (ShouldTrackPressure) {
assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker");
TopRPTracker.setPos(CurrentTop);
}
}
/// Move an instruction and update register pressure.
@ -841,10 +855,12 @@ void ScheduleDAGMI::scheduleMI(SUnit *SU, bool IsTopNode) {
TopRPTracker.setPos(MI);
}
// Update top scheduled pressure.
TopRPTracker.advance();
assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
updateScheduledPressure(TopRPTracker.getPressure().MaxSetPressure);
if (ShouldTrackPressure) {
// Update top scheduled pressure.
TopRPTracker.advance();
assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
updateScheduledPressure(TopRPTracker.getPressure().MaxSetPressure);
}
}
else {
assert(SU->isBottomReady() && "node still has unscheduled dependencies");
@ -860,12 +876,14 @@ void ScheduleDAGMI::scheduleMI(SUnit *SU, bool IsTopNode) {
moveInstruction(MI, CurrentBottom);
CurrentBottom = MI;
}
// Update bottom scheduled pressure.
SmallVector<unsigned, 8> LiveUses;
BotRPTracker.recede(&LiveUses);
assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
updatePressureDiffs(LiveUses);
updateScheduledPressure(BotRPTracker.getPressure().MaxSetPressure);
if (ShouldTrackPressure) {
// Update bottom scheduled pressure.
SmallVector<unsigned, 8> LiveUses;
BotRPTracker.recede(&LiveUses);
assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
updatePressureDiffs(LiveUses);
updateScheduledPressure(BotRPTracker.getPressure().MaxSetPressure);
}
}
}

28
lib/CodeGen/RegisterPressure.cpp
View File

@ -153,6 +153,24 @@ const LiveInterval *RegPressureTracker::getInterval(unsigned Reg) const {
return LIS->getCachedRegUnit(Reg);
}
void RegPressureTracker::reset() {
MBB = 0;
LIS = 0;
CurrSetPressure.clear();
LiveThruPressure.clear();
P.MaxSetPressure.clear();
if (RequireIntervals)
static_cast<IntervalPressure&>(P).reset();
else
static_cast<RegionPressure&>(P).reset();
LiveRegs.PhysRegs.clear();
LiveRegs.VirtRegs.clear();
UntiedDefs.clear();
}
/// Setup the RegPressureTracker.
///
/// TODO: Add support for pressure without LiveIntervals.
@ -163,6 +181,8 @@ void RegPressureTracker::init(const MachineFunction *mf,
MachineBasicBlock::const_iterator pos,
bool ShouldTrackUntiedDefs)
{
reset();
MF = mf;
TRI = MF->getTarget().getRegisterInfo();
RCI = rci;
@ -177,19 +197,11 @@ void RegPressureTracker::init(const MachineFunction *mf,
CurrPos = pos;
CurrSetPressure.assign(TRI->getNumRegPressureSets(), 0);
LiveThruPressure.clear();
if (RequireIntervals)
static_cast<IntervalPressure&>(P).reset();
else
static_cast<RegionPressure&>(P).reset();
P.MaxSetPressure = CurrSetPressure;
LiveRegs.PhysRegs.clear();
LiveRegs.PhysRegs.setUniverse(TRI->getNumRegs());
LiveRegs.VirtRegs.clear();
LiveRegs.VirtRegs.setUniverse(MRI->getNumVirtRegs());
UntiedDefs.clear();
if (TrackUntiedDefs)
UntiedDefs.setUniverse(MRI->getNumVirtRegs());
}