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RegisterPressureTracker: reword stale comments.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237544 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2015-05-17 23:40:27 +00:00
parent 2bb2ea8105
commit eddedaab45
2 changed files with 13 additions and 9 deletions
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3
lib/CodeGen/MachineScheduler.cpp
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@ -2611,8 +2611,7 @@ void GenericScheduler::tryCandidate(SchedCandidate &Cand,
TryCand, Cand, PhysRegCopy))
return;
// Avoid exceeding the target's limit. If signed PSetID is negative, it is
// invalid; convert it to INT_MAX to give it lowest priority.
// Avoid exceeding the target's limit.
if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.Excess,
Cand.RPDelta.Excess,
TryCand, Cand, RegExcess))

19
lib/CodeGen/RegisterPressure.cpp
View File

@ -750,9 +750,11 @@ void RegPressureTracker::bumpUpwardPressure(const MachineInstr *MI) {
///
/// This assumes that the current LiveOut set is sufficient.
///
/// FIXME: This is expensive for an on-the-fly query. We need to cache the
/// result per-SUnit with enough information to adjust for the current
/// scheduling position. But this works as a proof of concept.
/// This is expensive for an on-the-fly query because it calls
/// bumpUpwardPressure to recompute the pressure sets based on current
/// liveness. This mainly exists to verify correctness, e.g. with
/// -verify-misched. getUpwardPressureDelta is the fast version of this query
/// that uses the per-SUnit cache of the PressureDiff.
void RegPressureTracker::
getMaxUpwardPressureDelta(const MachineInstr *MI, PressureDiff *PDiff,
RegPressureDelta &Delta,
@ -809,10 +811,8 @@ getMaxUpwardPressureDelta(const MachineInstr *MI, PressureDiff *PDiff,
#endif
}
/// This is a prototype of the fast version of querying register pressure that
/// does not directly depend on current liveness. It's still slow because we
/// recompute pressure change on-the-fly. This implementation only exists to
/// prove correctness.
/// This is the fast version of querying register pressure that does not
/// directly depend on current liveness.
///
/// @param Delta captures information needed for heuristics.
///
@ -950,6 +950,11 @@ void RegPressureTracker::bumpDownwardPressure(const MachineInstr *MI) {
/// register units of that pressure set introduced by this instruction.
///
/// This assumes that the current LiveIn set is sufficient.
///
/// This is expensive for an on-the-fly query because it calls
/// bumpDownwardPressure to recompute the pressure sets based on current
/// liveness. We don't yet have a fast version of downward pressure tracking
/// analagous to getUpwardPressureDelta.
void RegPressureTracker::
getMaxDownwardPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta,
ArrayRef<PressureChange> CriticalPSets,