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MachineScheduler: Remove ineffective heuristic; NFC 

Currently all nodes get added to the NextSU list when they are released,
so any candidate must be in that list, making the heuristic ineffective.
Remove it for now, we can add it back later in a working fashion if
necessary.

llvm-svn: 282200
This commit is contained in:
Matthias Braun 2016-09-22 21:39:52 +00:00
parent c7957ef86c
commit 46533e614b
2 changed files with 0 additions and 19 deletions
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8
llvm/include/llvm/CodeGen/MachineScheduler.h
View File

@ -589,10 +589,6 @@ private:
/// instruction.
bool CheckPending;
// For heuristics, keep a list of the nodes that immediately depend on the
// most recently scheduled node.
SmallPtrSet<const SUnit*, 8> NextSUs;
/// Number of cycles it takes to issue the instructions scheduled in this
/// zone. It is defined as: scheduled-micro-ops / issue-width + stalls.
/// See getStalls().
@ -669,10 +665,6 @@ public:
/// Micro-ops issued in the current cycle
unsigned getCurrMOps() const { return CurrMOps; }
/// Return true if the given SU is used by the most recently scheduled
/// instruction.
bool isNextSU(const SUnit *SU) const { return NextSUs.count(SU); }
// The latency of dependence chains leading into this zone.
unsigned getDependentLatency() const { return DependentLatency; }

11
llvm/lib/CodeGen/MachineScheduler.cpp
View File

@ -1793,7 +1793,6 @@ void SchedBoundary::reset() {
Available.clear();
Pending.clear();
CheckPending = false;
NextSUs.clear();
CurrCycle = 0;
CurrMOps = 0;
MinReadyCycle = UINT_MAX;
@ -1994,9 +1993,6 @@ void SchedBoundary::releaseNode(SUnit *SU, unsigned ReadyCycle) {
Pending.push(SU);
else
Available.push(SU);
// Record this node as an immediate dependent of the scheduled node.
NextSUs.insert(SU);
}
void SchedBoundary::releaseTopNode(SUnit *SU) {
@ -2921,13 +2917,6 @@ void GenericScheduler::tryCandidate(SchedCandidate &Cand,
!Rem.IsAcyclicLatencyLimited && tryLatency(TryCand, Cand, *Zone))
return;
// Prefer immediate defs/users of the last scheduled instruction. This is a
// local pressure avoidance strategy that also makes the machine code
// readable.
if (tryGreater(Zone->isNextSU(TryCand.SU), Zone->isNextSU(Cand.SU),
TryCand, Cand, NextDefUse))
return;
// Fall through to original instruction order.
if ((Zone->isTop() && TryCand.SU->NodeNum < Cand.SU->NodeNum)
|| (!Zone->isTop() && TryCand.SU->NodeNum > Cand.SU->NodeNum)) {