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fix a bug in findNonImmUse (used by IsLegalToFold) where nodes with

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no id's would cause early exit allowing IsLegalToFold to return true
instead of false, producing a cyclic dag.

This was striking the new isel because it isn't using SelectNodeTo yet,
which theoretically is just an optimization.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96972 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-02-23 19:32:27 +00:00
parent 4548e02bd6
commit da244a091d
1 changed files with 14 additions and 2 deletions
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16
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@ -1318,8 +1318,20 @@ static SDNode *findFlagUse(SDNode *N) {
static bool findNonImmUse(SDNode *Use, SDNode* Def, SDNode *ImmedUse,
SDNode *Root,
SmallPtrSet<SDNode*, 16> &Visited) {
if (Use->getNodeId() < Def->getNodeId() ||
!Visited.insert(Use))
// The NodeID's are given uniques ID's where a node ID is guaranteed to be
// greater than all of its (recursive) operands. If we scan to a point where
// 'use' is smaller than the node we're scanning for, then we know we will
// never find it.
//
// The Use may be -1 (unassigned) if it is a newly allocated node. This can
// happen because we scan down to newly selected nodes in the case of flag
// uses.
if ((Use->getNodeId() < Def->getNodeId() && Use->getNodeId() != -1))
return false;
// Don't revisit nodes if we already scanned it and didn't fail, we know we
// won't fail if we scan it again.
if (!Visited.insert(Use))
return false;
for (unsigned i = 0, e = Use->getNumOperands(); i != e; ++i) {