Changes in directory llvm/lib/CodeGen/SelectionDAG:
DAGCombiner.cpp updated: 1.266 -> 1.267 --- Log message: Fix PR1114: http://llvm.org/PR1114 and CodeGen/Generic/2007-01-15-LoadSelectCycle.ll by being careful when folding "c ? load p : load q" that C doesn't reach either load. If so, folding this into load (c ? p : q) will induce a cycle in the graph. --- Diffs of the changes: (+41 -25) DAGCombiner.cpp | 66 ++++++++++++++++++++++++++++++++++---------------------- 1 files changed, 41 insertions(+), 25 deletions(-) Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.266 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.267 --- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.266 Mon Jan 15 22:55:25 2007 +++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Mon Jan 15 23:59:59 2007 @@ -3709,36 +3709,52 @@ // the right thing to do, but nothing uses srcvalues now. When they do, // turn SrcValue into a list of locations. SDOperand Addr; - if (TheSelect->getOpcode() == ISD::SELECT) - Addr = DAG.getNode(ISD::SELECT, LLD->getBasePtr().getValueType(), - TheSelect->getOperand(0), LLD->getBasePtr(), - RLD->getBasePtr()); - else - Addr = DAG.getNode(ISD::SELECT_CC, LLD->getBasePtr().getValueType(), + if (TheSelect->getOpcode() == ISD::SELECT) { + // Check that the condition doesn't reach either load. If so, folding + // this will induce a cycle into the DAG. + if (!LLD->isPredecessor(TheSelect->getOperand(0).Val) && + !RLD->isPredecessor(TheSelect->getOperand(0).Val)) { + Addr = DAG.getNode(ISD::SELECT, LLD->getBasePtr().getValueType(), + TheSelect->getOperand(0), LLD->getBasePtr(), + RLD->getBasePtr()); + } + } else { + // Check that the condition doesn't reach either load. If so, folding + // this will induce a cycle into the DAG. + if (!LLD->isPredecessor(TheSelect->getOperand(0).Val) && + !RLD->isPredecessor(TheSelect->getOperand(0).Val) && + !LLD->isPredecessor(TheSelect->getOperand(1).Val) && + !RLD->isPredecessor(TheSelect->getOperand(1).Val)) { + Addr = DAG.getNode(ISD::SELECT_CC, LLD->getBasePtr().getValueType(), TheSelect->getOperand(0), TheSelect->getOperand(1), LLD->getBasePtr(), RLD->getBasePtr(), TheSelect->getOperand(4)); - - SDOperand Load; - if (LLD->getExtensionType() == ISD::NON_EXTLOAD) - Load = DAG.getLoad(TheSelect->getValueType(0), LLD->getChain(), - Addr,LLD->getSrcValue(), LLD->getSrcValueOffset()); - else { - Load = DAG.getExtLoad(LLD->getExtensionType(), - TheSelect->getValueType(0), - LLD->getChain(), Addr, LLD->getSrcValue(), - LLD->getSrcValueOffset(), - LLD->getLoadedVT()); + } + } + + if (Addr.Val) { + SDOperand Load; + if (LLD->getExtensionType() == ISD::NON_EXTLOAD) + Load = DAG.getLoad(TheSelect->getValueType(0), LLD->getChain(), + Addr,LLD->getSrcValue(), + LLD->getSrcValueOffset()); + else { + Load = DAG.getExtLoad(LLD->getExtensionType(), + TheSelect->getValueType(0), + LLD->getChain(), Addr, LLD->getSrcValue(), + LLD->getSrcValueOffset(), + LLD->getLoadedVT()); + } + // Users of the select now use the result of the load. + CombineTo(TheSelect, Load); + + // Users of the old loads now use the new load's chain. We know the + // old-load value is dead now. + CombineTo(LHS.Val, Load.getValue(0), Load.getValue(1)); + CombineTo(RHS.Val, Load.getValue(0), Load.getValue(1)); + return true; } - // Users of the select now use the result of the load. - CombineTo(TheSelect, Load); - - // Users of the old loads now use the new load's chain. We know the - // old-load value is dead now. - CombineTo(LHS.Val, Load.getValue(0), Load.getValue(1)); - CombineTo(RHS.Val, Load.getValue(0), Load.getValue(1)); - return true; } } } _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
