Don't charge full latency for an anti-dependence, in this simplistic

pipeline model.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60733 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2008-12-09 00:26:46 +00:00
parent 55fdaec36a
commit aeac8f9cb4

View File

@ -52,8 +52,9 @@ int LatencyPriorityQueue::CalcLatency(const SUnit &SU) {
WorkList.push_back(&SU);
while (!WorkList.empty()) {
const SUnit *Cur = WorkList.back();
unsigned CurLatency = Cur->Latency;
bool AllDone = true;
int MaxSuccLatency = 0;
unsigned MaxSuccLatency = 0;
for (SUnit::const_succ_iterator I = Cur->Succs.begin(),E = Cur->Succs.end();
I != E; ++I) {
int SuccLatency = Latencies[I->Dep->NodeNum];
@ -61,11 +62,14 @@ int LatencyPriorityQueue::CalcLatency(const SUnit &SU) {
AllDone = false;
WorkList.push_back(I->Dep);
} else {
MaxSuccLatency = std::max(MaxSuccLatency, SuccLatency);
// This assumes that there's no delay for reusing registers.
unsigned NewLatency =
SuccLatency + ((I->isCtrl && I->Reg != 0) ? 1 : CurLatency);
MaxSuccLatency = std::max(MaxSuccLatency, NewLatency);
}
}
if (AllDone) {
Latencies[Cur->NodeNum] = MaxSuccLatency + Cur->Latency;
Latencies[Cur->NodeNum] = MaxSuccLatency;
WorkList.pop_back();
}
}