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misched: Infrastructure for weak DAG edges.

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This adds support for weak DAG edges to the general scheduling
infrastructure in preparation for MachineScheduler support for
heuristics based on weak edges.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167738 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick
2012-11-12 19:28:57 +00:00
parent 95d8afc5f2
commit ae692f2bae
8 changed files with 142 additions and 66 deletions
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lib/CodeGen/MachineScheduler.cpp
+18 -8
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@@ -310,6 +310,10 @@ void ReadyQueue::dump() {
void ScheduleDAGMI::releaseSucc(SUnit *SU, SDep *SuccEdge) {
SUnit *SuccSU = SuccEdge->getSUnit();
if (SuccEdge->isWeak()) {
--SuccSU->WeakPredsLeft;
return;
}
#ifndef NDEBUG
if (SuccSU->NumPredsLeft == 0) {
dbgs() << "*** Scheduling failed! ***\n";
@@ -338,6 +342,10 @@ void ScheduleDAGMI::releaseSuccessors(SUnit *SU) {
void ScheduleDAGMI::releasePred(SUnit *SU, SDep *PredEdge) {
SUnit *PredSU = PredEdge->getSUnit();
if (PredEdge->isWeak()) {
--PredSU->WeakSuccsLeft;
return;
}
#ifndef NDEBUG
if (PredSU->NumSuccsLeft == 0) {
dbgs() << "*** Scheduling failed! ***\n";
@@ -530,17 +538,20 @@ void ScheduleDAGMI::postprocessDAG() {
}
// Release all DAG roots for scheduling.
//
// Nodes with unreleased weak edges can still be roots.
void ScheduleDAGMI::releaseRoots() {
SmallVector<SUnit*, 16> BotRoots;
for (std::vector<SUnit>::iterator
I = SUnits.begin(), E = SUnits.end(); I != E; ++I) {
SUnit *SU = &(*I);
// A SUnit is ready to top schedule if it has no predecessors.
if (I->Preds.empty())
SchedImpl->releaseTopNode(&(*I));
if (!I->NumPredsLeft && SU != &EntrySU)
SchedImpl->releaseTopNode(SU);
// A SUnit is ready to bottom schedule if it has no successors.
if (I->Succs.empty())
BotRoots.push_back(&(*I));
if (!I->NumSuccsLeft && SU != &ExitSU)
BotRoots.push_back(SU);
}
// Release bottom roots in reverse order so the higher priority nodes appear
// first. This is more natural and slightly more efficient.
@@ -555,13 +566,12 @@ void ScheduleDAGMI::initQueues() {
// Initialize the strategy before modifying the DAG.
SchedImpl->initialize(this);
// Release edges from the special Entry node or to the special Exit node.
// Release all DAG roots for scheduling, not including EntrySU/ExitSU.
releaseRoots();
releaseSuccessors(&EntrySU);
releasePredecessors(&ExitSU);
// Release all DAG roots for scheduling.
releaseRoots();
SchedImpl->registerRoots();
CurrentTop = nextIfDebug(RegionBegin, RegionEnd);