diff options
Diffstat (limited to 'lib/CodeGen/SelectionDAG/SelectionDAG.cpp')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index b83d537e37..d8124e6d7c 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -4388,9 +4388,16 @@ void SelectionDAG::ReplaceAllUsesWith(SDValue FromN, SDValue To, "Cannot replace with this method!"); assert(From != To.getNode() && "Cannot replace uses of with self"); - while (!From->use_empty()) { - SDNode::use_iterator UI = From->use_begin(); + // Iterate over all the existing uses of From. This specifically avoids + // visiting any new uses of From that arrise while the replacement is + // happening, because any such uses would be the result of CSE: If an + // existing node looks like From after one of its operands is replaced + // by To, we don't want to replace of all its users with To too. + // See PR3018 for more info. + SDNode::use_iterator UI = From->use_begin(), UE = From->use_end(); + while (UI != UE) { SDNode *U = *UI; + do ++UI; while (UI != UE && *UI == U); // This node is about to morph, remove its old self from the CSE maps. RemoveNodeFromCSEMaps(U); @@ -4437,9 +4444,12 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From, SDNode *To, if (From == To) return; - while (!From->use_empty()) { - SDNode::use_iterator UI = From->use_begin(); + // Iterate over just the existing users of From. See the comments in + // the ReplaceAllUsesWith above. + SDNode::use_iterator UI = From->use_begin(), UE = From->use_end(); + while (UI != UE) { SDNode *U = *UI; + do ++UI; while (UI != UE && *UI == U); // This node is about to morph, remove its old self from the CSE maps. RemoveNodeFromCSEMaps(U); @@ -4480,9 +4490,12 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From, if (From->getNumValues() == 1) // Handle the simple case efficiently. return ReplaceAllUsesWith(SDValue(From, 0), To[0], UpdateListener); - while (!From->use_empty()) { - SDNode::use_iterator UI = From->use_begin(); + // Iterate over just the existing users of From. See the comments in + // the ReplaceAllUsesWith above. + SDNode::use_iterator UI = From->use_begin(), UE = From->use_end(); + while (UI != UE) { SDNode *U = *UI; + do ++UI; while (UI != UE && *UI == U); // This node is about to morph, remove its old self from the CSE maps. RemoveNodeFromCSEMaps(U); |