search for: preschedulenodeswithmultipleus

Hi, I have reasoned through and believe the problem is with the PrescheduleNodesWithMultipleUses. Take the following DAG (arrow to predecessor): Destroy Destroy ^ ^ | | | | SetUp----->PredSU <-----SU ^ ^ ^ | | | | | | ----------...

Here is a bit more data. After PrescheduleNodesWithMultipleUses has been run, the following Predecessor/Successor links are 'dumpAll'ed. (I attach the full dumpAll before & after "Prescheduling SU #7 next to PredSU #4 to guide scheduling in the presence of multiple uses") SU(3) Predecessors: val SU(5): Latency=1 ch SU(7): Laten...

...::TargetRegisterClass* llvm::TargetRegisterInfo::getMinimalPhysRegClass(unsigned int, llvm::EVT) const: Assertion `BestRC && "Couldn't find the register class"' failed. The interesting thing about this failure is that the Predecessor/Successor of two nodes was changed by PrescheduleNodesWithMultipleUses(). If they were not, the AvailableQueue would have had nodes, and all would have been fine. I am quite uneasy over how PrescheduleNodesWithMultipleUses() has changed the Predecessor/Successor. It seems to have changed the DAG into something impossible to schedule - I need to look more carefully t...

...'Destroy' & 'SetUp' the wrong way around! Robert ________________________________ From: llvmdev-bounces at cs.uiuc.edu [llvmdev-bounces at cs.uiuc.edu] on behalf of Robert Lytton [robert at xmos.com] Sent: 21 August 2013 18:34 To: llvmdev at cs.uiuc.edu Subject: Re: [LLVMdev] PrescheduleNodesWithMultipleUses() causing failure in PickNodeToScheduleBottomUp() ??? Hi, I have reasoned through and believe the problem is with the PrescheduleNodesWithMultipleUses. Take the following DAG (arrow to predecessor): Destroy Destroy ^ ^ | | |...

On Thu, Aug 22, 2013 at 4:15 AM, Robert Lytton <robert at xmos.com> wrote: > > > Outstanding issues > ============ > > 1. Is it too aggressive in searching predecessors and successors? > Should the algorithm give up and assume the worst if the depth of > search reaches a predefined limit? > > 2. Should the initial search for 'SetUp1' and

...Unit. 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::...

Hi I have brought everything together in this email. The problem ======== Take the following DAG (arrow to predecessor): SetUp2 SetUp1 ^ ^ | | | | Destroy2---->PredSU <----SU ^ ^ ^ | | | | | | ----------- | ---------