Fold the ShrinkDemandedOps pass into the regular DAGCombiner pass,
which is faster, simpler, and less surprising.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106263 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 2ee5f0b..48b4d89 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -372,102 +372,6 @@
};
}
-/// TrivialTruncElim - Eliminate some trivial nops that can result from
-/// ShrinkDemandedOps: (trunc (ext n)) -> n.
-static bool TrivialTruncElim(SDValue Op,
- TargetLowering::TargetLoweringOpt &TLO) {
- SDValue N0 = Op.getOperand(0);
- EVT VT = Op.getValueType();
- if ((N0.getOpcode() == ISD::ZERO_EXTEND ||
- N0.getOpcode() == ISD::SIGN_EXTEND ||
- N0.getOpcode() == ISD::ANY_EXTEND) &&
- N0.getOperand(0).getValueType() == VT) {
- return TLO.CombineTo(Op, N0.getOperand(0));
- }
- return false;
-}
-
-/// ShrinkDemandedOps - A late transformation pass that shrink expressions
-/// using TargetLowering::TargetLoweringOpt::ShrinkDemandedOp. It converts
-/// x+y to (VT)((SmallVT)x+(SmallVT)y) if the casts are free.
-void SelectionDAGISel::ShrinkDemandedOps() {
- SmallVector<SDNode*, 128> Worklist;
- SmallPtrSet<SDNode*, 128> InWorklist;
-
- // Add all the dag nodes to the worklist.
- Worklist.reserve(CurDAG->allnodes_size());
- for (SelectionDAG::allnodes_iterator I = CurDAG->allnodes_begin(),
- E = CurDAG->allnodes_end(); I != E; ++I) {
- Worklist.push_back(I);
- InWorklist.insert(I);
- }
-
- TargetLowering::TargetLoweringOpt TLO(*CurDAG, true, true, true);
- while (!Worklist.empty()) {
- SDNode *N = Worklist.pop_back_val();
- InWorklist.erase(N);
-
- if (N->use_empty() && N != CurDAG->getRoot().getNode()) {
- // Deleting this node may make its operands dead, add them to the worklist
- // if they aren't already there.
- for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
- if (InWorklist.insert(N->getOperand(i).getNode()))
- Worklist.push_back(N->getOperand(i).getNode());
-
- CurDAG->DeleteNode(N);
- continue;
- }
-
- // Run ShrinkDemandedOp on scalar binary operations.
- if (N->getNumValues() != 1 ||
- !N->getValueType(0).isSimple() || !N->getValueType(0).isInteger())
- continue;
-
- unsigned BitWidth = N->getValueType(0).getScalarType().getSizeInBits();
- APInt Demanded = APInt::getAllOnesValue(BitWidth);
- APInt KnownZero, KnownOne;
- if (!TLI.SimplifyDemandedBits(SDValue(N, 0), Demanded,
- KnownZero, KnownOne, TLO) &&
- (N->getOpcode() != ISD::TRUNCATE ||
- !TrivialTruncElim(SDValue(N, 0), TLO)))
- continue;
-
- // Revisit the node.
- assert(!InWorklist.count(N) && "Already in worklist");
- Worklist.push_back(N);
- InWorklist.insert(N);
-
- // Replace the old value with the new one.
- DEBUG(errs() << "\nShrinkDemandedOps replacing ";
- TLO.Old.getNode()->dump(CurDAG);
- errs() << "\nWith: ";
- TLO.New.getNode()->dump(CurDAG);
- errs() << '\n');
-
- if (InWorklist.insert(TLO.New.getNode()))
- Worklist.push_back(TLO.New.getNode());
-
- SDOPsWorkListRemover DeadNodes(Worklist, InWorklist);
- CurDAG->ReplaceAllUsesOfValueWith(TLO.Old, TLO.New, &DeadNodes);
-
- if (!TLO.Old.getNode()->use_empty()) continue;
-
- for (unsigned i = 0, e = TLO.Old.getNode()->getNumOperands();
- i != e; ++i) {
- SDNode *OpNode = TLO.Old.getNode()->getOperand(i).getNode();
- if (OpNode->hasOneUse()) {
- // Add OpNode to the end of the list to revisit.
- DeadNodes.RemoveFromWorklist(OpNode);
- Worklist.push_back(OpNode);
- InWorklist.insert(OpNode);
- }
- }
-
- DeadNodes.RemoveFromWorklist(TLO.Old.getNode());
- CurDAG->DeleteNode(TLO.Old.getNode());
- }
-}
-
void SelectionDAGISel::ComputeLiveOutVRegInfo() {
SmallPtrSet<SDNode*, 128> VisitedNodes;
SmallVector<SDNode*, 128> Worklist;
@@ -636,10 +540,8 @@
DEBUG(dbgs() << "Optimized legalized selection DAG:\n");
DEBUG(CurDAG->dump());
- if (OptLevel != CodeGenOpt::None) {
- ShrinkDemandedOps();
+ if (OptLevel != CodeGenOpt::None)
ComputeLiveOutVRegInfo();
- }
if (ViewISelDAGs) CurDAG->viewGraph("isel input for " + BlockName);