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Reapply r106634, now that the bug it exposed is fixed.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106746 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2010-06-24 14:30:44 +00:00
parent fef8c4eb54
commit 4e39e9da0f
9 changed files with 62 additions and 119 deletions
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lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+1 -99
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@@ -372,102 +372,6 @@ public:
};
}
/// 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;
@@ -617,10 +521,8 @@ MachineBasicBlock *SelectionDAGISel::CodeGenAndEmitDAG(MachineBasicBlock *BB) {
DEBUG(dbgs() << "Optimized legalized selection DAG:\n"; CurDAG->dump());
if (OptLevel != CodeGenOpt::None) {
ShrinkDemandedOps();
if (OptLevel != CodeGenOpt::None)
ComputeLiveOutVRegInfo();
}
if (ViewISelDAGs) CurDAG->viewGraph("isel input for " + BlockName);