From b2215030d6a6c3096ed5da8fde43c4eed7165768 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 12 Mar 2006 03:52:09 +0000 Subject: [PATCH] Chain operands aren't real uses: they don't require the full latency of the predecessor to finish before they can start. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26717 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp index ac0543d7d79..f3d97fe18c5 100644 --- a/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp +++ b/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp @@ -387,8 +387,6 @@ void ScheduleDAGList::dumpSchedule() const { } /// Schedule - Schedule the DAG using list scheduling. -/// FIXME: Right now it only supports the burr (bottom up register reducing) -/// heuristic. void ScheduleDAGList::Schedule() { DEBUG(std::cerr << "********** List Scheduling **********\n"); @@ -552,8 +550,16 @@ void ScheduleDAGList::ReleaseSucc(SUnit *SuccSU, bool isChain) { unsigned AvailableCycle = 0; for (std::set >::iterator I = SuccSU->Preds.begin(), E = SuccSU->Preds.end(); I != E; ++I) { - AvailableCycle = std::max(AvailableCycle, - I->first->Cycle + I->first->Latency); + // If this is a token edge, we don't need to wait for the full latency of + // the preceeding instruction (e.g. a long-latency load) unless there is + // also some other data dependence. + unsigned PredDoneCycle = I->first->Cycle; + if (!I->second) + PredDoneCycle += I->first->Latency; + else + PredDoneCycle += 1; + + AvailableCycle = std::max(AvailableCycle, PredDoneCycle); } PendingQueue.push_back(std::make_pair(AvailableCycle, SuccSU));