PrescheduleNodesWithMultipleUses() probable mistake.

Project Infrastructure LLVM Dev List Archives
#1

Hi,

At the moment the same test is being ran twice - same output so pointless!
I believe this may not be what was intended.
The change below runs the virtual register test the second time on the Predecessor SUnit.

Robert

diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index f5fe168…6e888da
— a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -2850,7 +2850,7 @@ void RegReductionPQBase::PrescheduleNodesWithMultipleUses() {
continue;
// Avoid prescheduling to copies from virtual registers, which don’t behave
// like other nodes from the perspective of scheduling heuristics.

  • if (SDNode *N = SU->getNode())
  • if (SDNode *N = PredSU->getNode())
    if (N->getOpcode() == ISD::CopyFromReg &&
    TargetRegisterInfo::isVirtualRegister
    (cast(N->getOperand(1))->getReg()))
#2

Dan,

You wrote this code...What do you think? :slight_smile:

-bw