Use a latency value of 0 for the artificial edges inserted by

AddPseudoTwoAddrDeps. This lets the scheduling infrastructure
avoid recalculating node heights. In very large testcases this
was a major bottleneck. Thanks to Roman Levenstein for finding
this!

As a side effect, fold-pcmpeqd-0.ll is now scheduled better
and it no longer requires spilling on x86-32.

llvm-svn: 61778

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index 436056c6445..676a69bd633 100644
--- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -1252,7 +1252,7 @@ void RegReductionPriorityQueue<SF>::AddPseudoTwoAddrDeps() {
             !scheduleDAG->IsReachable(SuccSU, SU)) {
           DOUT << "Adding a pseudo-two-addr edge from SU # " << SU->NodeNum
                << " to SU #" << SuccSU->NodeNum << "\n";
-          scheduleDAG->AddPred(SU, SDep(SuccSU, SDep::Order, /*Latency=*/1,
+          scheduleDAG->AddPred(SU, SDep(SuccSU, SDep::Order, /*Latency=*/0,
                                         /*Reg=*/0, /*isMustAlias=*/false,
                                         /*isArtificial=*/true));
         }