From cc358128772e39675be1db35eb608bb2ce1bbe1a Mon Sep 17 00:00:00 2001 From: Pawel Bylica Date: Wed, 24 Jun 2015 12:49:42 +0000 Subject: Fix instruction scheduling live register tracking Summary: This patch fixes PR23405 (https://llvm.org/bugs/show_bug.cgi?id=23405). During a node unscheduling an entry in LiveRegGens can be replaced with a new value. That corrupts the live reg tracking and LiveReg* structure is not cleared as should be during unscheduling. Problematic condition that enforces Gen replacement is `I->getSUnit()->getHeight() < LiveRegGens[I->getReg()]->getHeight()`. This condition should be checked only if LiveRegGen was set in current node unscheduling. Test Plan: Regression test included. Reviewers: hfinkel, atrick Reviewed By: atrick Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D9993 llvm-svn: 240538 --- .../lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp | 25 +++++++++++++++------- 1 file changed, 17 insertions(+), 8 deletions(-) (limited to 'llvm/lib/CodeGen') diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp index fd0fa31842b..12ca59ff18c 100644 --- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp @@ -848,17 +848,26 @@ void ScheduleDAGRRList::UnscheduleNodeBottomUp(SUnit *SU) { } } - for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end(); - I != E; ++I) { - if (I->isAssignedRegDep()) { - if (!LiveRegDefs[I->getReg()]) + for (auto &Succ : SU->Succs) { + if (Succ.isAssignedRegDep()) { + auto Reg = Succ.getReg(); + if (!LiveRegDefs[Reg]) ++NumLiveRegs; // This becomes the nearest def. Note that an earlier def may still be // pending if this is a two-address node. - LiveRegDefs[I->getReg()] = SU; - if (LiveRegGens[I->getReg()] == nullptr || - I->getSUnit()->getHeight() < LiveRegGens[I->getReg()]->getHeight()) - LiveRegGens[I->getReg()] = I->getSUnit(); + LiveRegDefs[Reg] = SU; + + // Update LiveRegGen only if was empty before this unscheduling. + // This is to avoid incorrect updating LiveRegGen set in previous run. + if (!LiveRegGens[Reg]) { + // Find the successor with the lowest height. + LiveRegGens[Reg] = Succ.getSUnit(); + for (auto &Succ2 : SU->Succs) { + if (Succ2.isAssignedRegDep() && Succ2.getReg() == Reg && + Succ2.getSUnit()->getHeight() < LiveRegGens[Reg]->getHeight()) + LiveRegGens[Reg] = Succ2.getSUnit(); + } + } } } if (SU->getHeight() < MinAvailableCycle) -- cgit v1.2.3