diff --git a/include/llvm/CodeGen/SelectionDAGNodes.h b/include/llvm/CodeGen/SelectionDAGNodes.h index 30823833b79..fe1d4b68c2e 100644 --- a/include/llvm/CodeGen/SelectionDAGNodes.h +++ b/include/llvm/CodeGen/SelectionDAGNodes.h @@ -780,6 +780,14 @@ public: inline bool isTargetOpcode() const; inline unsigned getTargetOpcode() const; + + /// reachesChainWithoutSideEffects - Return true if this operand (which must + /// be a chain) reaches the specified operand without crossing any + /// side-effecting instructions. In practice, this looks through token + /// factors and non-volatile loads. In order to remain efficient, this only + /// looks a couple of nodes in, it does not do an exhaustive search. + bool reachesChainWithoutSideEffects(SDOperand Dest, unsigned Depth = 2) const; + /// hasOneUse - Return true if there is exactly one operation using this /// result value of the defining operator. inline bool hasOneUse() const; diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 0bb11fa330b..09e0c3e0008 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -4122,33 +4122,6 @@ SDOperand DAGCombiner::visitLOAD(SDNode *N) { return SDOperand(); } -/// ReachesChainWithoutSideEffects - Do a little local search to see if Src can -/// reach Dest without any side effects like a store, or call. Non-volatile -/// loads are ok though. -static bool ReachesChainWithoutSideEffects(SDOperand Src, SDOperand Dest, - unsigned Depth = 0) { - if (Src == Dest) return true; - - // Don't search too deeply, we just want to be able to see through - // TokenFactor's etc. - if (Depth == 2) return false; - - // If this is a token factor, all inputs to the TF happen in parallel. If any - // of the operands of the TF reach dest, then we can do the xform. - if (Src.getOpcode() == ISD::TokenFactor) { - for (unsigned i = 0, e = Src.getNumOperands(); i != e; ++i) - if (ReachesChainWithoutSideEffects(Src.getOperand(i), Dest, Depth+1)) - return true; - return false; - } - - // Loads don't have side effects, look through them. - if (LoadSDNode *Ld = dyn_cast(Src)) { - if (!Ld->isVolatile()) - return ReachesChainWithoutSideEffects(Ld->getChain(), Dest, Depth+1); - } - return false; -} SDOperand DAGCombiner::visitSTORE(SDNode *N) { StoreSDNode *ST = cast(N); @@ -4283,7 +4256,7 @@ SDOperand DAGCombiner::visitSTORE(SDNode *N) { !ST->isVolatile() && // There can't be any side effects between the load and store, such as // a call or store. - ReachesChainWithoutSideEffects(Chain, SDOperand(Ld, 1))) { + Chain.reachesChainWithoutSideEffects(SDOperand(Ld, 1))) { // The store is dead, remove it. return Chain; } diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 381e9dec646..67da854aa4f 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -3562,6 +3562,37 @@ bool SDNode::isOperand(SDNode *N) const { return false; } +/// reachesChainWithoutSideEffects - Return true if this operand (which must +/// be a chain) reaches the specified operand without crossing any +/// side-effecting instructions. In practice, this looks through token +/// factors and non-volatile loads. In order to remain efficient, this only +/// looks a couple of nodes in, it does not do an exhaustive search. +bool SDOperand::reachesChainWithoutSideEffects(SDOperand Dest, + unsigned Depth) const { + if (*this == Dest) return true; + + // Don't search too deeply, we just want to be able to see through + // TokenFactor's etc. + if (Depth == 0) return false; + + // If this is a token factor, all inputs to the TF happen in parallel. If any + // of the operands of the TF reach dest, then we can do the xform. + if (getOpcode() == ISD::TokenFactor) { + for (unsigned i = 0, e = getNumOperands(); i != e; ++i) + if (getOperand(i).reachesChainWithoutSideEffects(Dest, Depth-1)) + return true; + return false; + } + + // Loads don't have side effects, look through them. + if (LoadSDNode *Ld = dyn_cast(*this)) { + if (!Ld->isVolatile()) + return Ld->getChain().reachesChainWithoutSideEffects(Dest, Depth-1); + } + return false; +} + + static void findPredecessor(SDNode *N, const SDNode *P, bool &found, SmallPtrSet &Visited) { if (found || !Visited.insert(N))