Add a simple target-independent heuristic to allow targets with no
instruction itinerary data to back-schedule loads.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61070 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index 30e1846..fa42d39 100644
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -225,6 +225,12 @@
// all nodes flagged together into this SUnit.
SU->Latency =
InstrItins.getLatency(SU->getInstr()->getDesc().getSchedClass());
+
+ // Simplistic target-independent heuristic: assume that loads take
+ // extra time.
+ if (InstrItins.isEmpty())
+ if (SU->getInstr()->getDesc().mayLoad())
+ SU->Latency += 2;
}
void ScheduleDAGInstrs::dumpNode(const SUnit *SU) const {