Index: src/IceCfgNode.cpp |
diff --git a/src/IceCfgNode.cpp b/src/IceCfgNode.cpp |
index cb8d97e95ade4a9da16f91d828fe471885538945..0ccc6ea11268f5501cde38bddfc6a95e60f7a900 100644 |
--- a/src/IceCfgNode.cpp |
+++ b/src/IceCfgNode.cpp |
@@ -80,6 +80,46 @@ void CfgNode::computeSuccessors() { |
OutEdges = Insts.rbegin()->getTerminatorEdges(); |
} |
+// Validate each Phi instruction in the node with respect to control flow. For |
+// every phi argument, its label must appear in the predecessor list. For each |
+// predecessor, there must be a phi argument with that label. We don't check |
+// that phi arguments with the same label have the same value. |
+void CfgNode::validatePhis() { |
+ for (Inst &Instr : Phis) { |
+ auto *Phi = llvm::cast<InstPhi>(&Instr); |
+ // We do a simple O(N^2) algorithm to check for consistency. Even so, it |
+ // shows up as only about 0.2% of the total translation time. But if |
+ // necessary, we could improve the complexity by using a hash table to count |
+ // how many times each node is referenced in the Phi instruction, and how |
+ // many times each node is referenced in the incoming edge list, and compare |
+ // the two for equality. |
+ for (SizeT i = 0; i < Phi->getSrcSize(); ++i) { |
+ CfgNode *Label = Phi->getLabel(i); |
+ bool Found = false; |
+ for (CfgNode *InNode : getInEdges()) { |
+ if (InNode == Label) { |
+ Found = true; |
+ break; |
+ } |
+ } |
+ if (!Found) |
+ llvm::report_fatal_error("Phi error: label for bad incoming edge"); |
+ } |
+ for (CfgNode *InNode : getInEdges()) { |
+ bool Found = false; |
+ for (SizeT i = 0; i < Phi->getSrcSize(); ++i) { |
+ CfgNode *Label = Phi->getLabel(i); |
+ if (InNode == Label) { |
+ Found = true; |
+ break; |
+ } |
+ } |
+ if (!Found) |
+ llvm::report_fatal_error("Phi error: missing label for incoming edge"); |
+ } |
+ } |
+} |
+ |
// This does part 1 of Phi lowering, by creating a new dest variable |
// for each Phi instruction, replacing the Phi instruction's dest with |
// that variable, and adding an explicit assignment of the old dest to |