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Rewrite the SDep class, and simplify some of the related code.

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The Cost field is removed. It was only being used in a very limited way,
to indicate when the scheduler should attempt to protect a live register,
and it isn't really needed to do that. If we ever want the scheduler to
start inserting copies in non-prohibitive situations, we'll have to
rethink some things anyway.

A Latency field is added. Instead of giving each node a single
fixed latency, each edge can have its own latency. This will eventually
be used to model various micro-architecture properties more accurately.

The PointerIntPair class and an internal union are now used, which
reduce the overall size.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60806 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2008-12-09 22:54:47 +00:00
parent 5a45bf1b48
commit 54e4c36a73
12 changed files with 526 additions and 376 deletions
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16
lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp
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@@ -78,7 +78,7 @@ public:
void Schedule();
private:
void ReleaseSucc(SUnit *SU, SUnit *SuccSU, bool isChain);
void ReleaseSucc(SUnit *SU, const SDep &D);
void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
void ListScheduleTopDown();
};
@@ -107,7 +107,8 @@ void ScheduleDAGList::Schedule() {
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
/// the PendingQueue if the count reaches zero. Also update its cycle bound.
void ScheduleDAGList::ReleaseSucc(SUnit *SU, SUnit *SuccSU, bool isChain) {
void ScheduleDAGList::ReleaseSucc(SUnit *SU, const SDep &D) {
SUnit *SuccSU = D.getSUnit();
--SuccSU->NumPredsLeft;
#ifndef NDEBUG
@@ -121,14 +122,7 @@ void ScheduleDAGList::ReleaseSucc(SUnit *SU, SUnit *SuccSU, bool isChain) {
// Compute the cycle when this SUnit actually becomes available. This
// is the max of the start time of all predecessors plus their latencies.
// If this is a token edge, we don't need to wait for the latency of the
// preceeding instruction (e.g. a long-latency load) unless there is also
// some other data dependence.
unsigned PredDoneCycle = SU->Cycle;
if (!isChain)
PredDoneCycle += SU->Latency;
else if (SU->Latency)
PredDoneCycle += 1;
unsigned PredDoneCycle = SU->Cycle + SU->Latency;
SuccSU->CycleBound = std::max(SuccSU->CycleBound, PredDoneCycle);
if (SuccSU->NumPredsLeft == 0) {
@@ -149,7 +143,7 @@ void ScheduleDAGList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
// Top down: release successors.
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I)
ReleaseSucc(SU, I->Dep, I->isCtrl);
ReleaseSucc(SU, *I);
SU->isScheduled = true;
AvailableQueue->ScheduledNode(SU);