Fix a tricky issue in the SimplifyDemandedBits code where CombineTo wasn't
exactly the API we wanted to call into. This fixes the crash on crafty last
night.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26269 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index f1d0a9b..4f7df4f 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -99,15 +99,40 @@
return SDOperand(N, 0);
}
- bool DemandedBitsAreZero(SDOperand Op, uint64_t DemandedMask) {
+ /// SimplifyDemandedBits - Check the specified integer node value to see if
+ /// it can be simplified or if things is uses can be simplified by bit
+ /// propagation. If so, return true.
+ bool SimplifyDemandedBits(SDOperand Op) {
TargetLowering::TargetLoweringOpt TLO(DAG);
uint64_t KnownZero, KnownOne;
- if (TLI.SimplifyDemandedBits(Op, DemandedMask, KnownZero, KnownOne, TLO)){
- WorkList.push_back(Op.Val);
- CombineTo(TLO.Old.Val, TLO.New);
- return true;
- }
- return false;
+ uint64_t Demanded = MVT::getIntVTBitMask(Op.getValueType());
+ if (!TLI.SimplifyDemandedBits(Op, Demanded, KnownZero, KnownOne, TLO))
+ return false;
+
+ // Revisit the node.
+ WorkList.push_back(Op.Val);
+
+ // Replace the old value with the new one.
+ ++NodesCombined;
+ DEBUG(std::cerr << "\nReplacing "; TLO.Old.Val->dump();
+ std::cerr << "\nWith: "; TLO.New.Val->dump());
+
+ std::vector<SDNode*> NowDead;
+ DAG.ReplaceAllUsesOfValueWith(TLO.Old, TLO.New, NowDead);
+
+ // Push the new node and any (now) users onto the worklist.
+ WorkList.push_back(TLO.New.Val);
+ AddUsersToWorkList(TLO.New.Val);
+
+ // Nodes can end up on the worklist more than once. Make sure we do
+ // not process a node that has been replaced.
+ removeFromWorkList(TLO.Old.Val);
+ for (unsigned i = 0, e = NowDead.size(); i != e; ++i)
+ removeFromWorkList(NowDead[i]);
+
+ // Finally, since the node is now dead, remove it from the graph.
+ DAG.DeleteNode(TLO.Old.Val);
+ return true;
}
SDOperand CombineTo(SDNode *N, SDOperand Res) {
@@ -985,7 +1010,7 @@
}
// fold (and (sign_extend_inreg x, i16 to i32), 1) -> (and x, 1)
// fold (and (sra)) -> (and (srl)) when possible.
- if (DemandedBitsAreZero(SDOperand(N, 0), MVT::getIntVTBitMask(VT)))
+ if (SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand();
// fold (zext_inreg (extload x)) -> (zextload x)
if (N0.getOpcode() == ISD::EXTLOAD) {
@@ -1267,7 +1292,7 @@
// if (shl x, c) is known to be zero, return 0
if (TLI.MaskedValueIsZero(SDOperand(N, 0), MVT::getIntVTBitMask(VT)))
return DAG.getConstant(0, VT);
- if (DemandedBitsAreZero(SDOperand(N,0), MVT::getIntVTBitMask(VT)))
+ if (SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand();
// fold (shl (shl x, c1), c2) -> 0 or (shl x, c1+c2)
if (N1C && N0.getOpcode() == ISD::SHL &&