+static cl::opt<bool>
+EnableExpensiveChecks("enable-legalize-types-checking", cl::Hidden);
+
+/// PerformExpensiveChecks - Do extensive, expensive, sanity checking.
+void DAGTypeLegalizer::PerformExpensiveChecks() {
+ // If a node is not processed, then none of its values should be mapped by any
+ // of PromotedIntegers, ExpandedIntegers, ..., ReplacedValues.
+
+ // If a node is processed, then each value with an illegal type must be mapped
+ // by exactly one of PromotedIntegers, ExpandedIntegers, ..., ReplacedValues.
+ // Values with a legal type may be mapped by ReplacedValues, but not by any of
+ // the other maps.
+
+ // Note that these invariants may not hold momentarily when processing a node:
+ // the node being processed may be put in a map before being marked Processed.
+
+ // Note that it is possible to have nodes marked NewNode in the DAG. This can
+ // occur in two ways. Firstly, a node may be created during legalization but
+ // never passed to the legalization core. This is usually due to the implicit
+ // folding that occurs when using the DAG.getNode operators. Secondly, a new
+ // node may be passed to the legalization core, but when analyzed may morph
+ // into a different node, leaving the original node as a NewNode in the DAG.
+ // A node may morph if one of its operands changes during analysis. Whether
+ // it actually morphs or not depends on whether, after updating its operands,
+ // it is equivalent to an existing node: if so, it morphs into that existing
+ // node (CSE). An operand can change during analysis if the operand is a new
+ // node that morphs, or it is a processed value that was mapped to some other
+ // value (as recorded in ReplacedValues) in which case the operand is turned
+ // into that other value. If a node morphs then the node it morphed into will
+ // be used instead of it for legalization, however the original node continues
+ // to live on in the DAG.
+ // The conclusion is that though there may be nodes marked NewNode in the DAG,
+ // all uses of such nodes are also marked NewNode: the result is a fungus of
+ // NewNodes growing on top of the useful nodes, and perhaps using them, but
+ // not used by them.
+
+ // If a value is mapped by ReplacedValues, then it must have no uses, except
+ // by nodes marked NewNode (see above).
+
+ // The final node obtained by mapping by ReplacedValues is not marked NewNode.
+ // Note that ReplacedValues should be applied iteratively.
+
+ // Note that the ReplacedValues map may also map deleted nodes (by iterating
+ // over the DAG we never dereference deleted nodes). This means that it may
+ // also map nodes marked NewNode if the deallocated memory was reallocated as
+ // another node, and that new node was not seen by the LegalizeTypes machinery
+ // (for example because it was created but not used). In general, we cannot
+ // distinguish between new nodes and deleted nodes.
+ SmallVector<SDNode*, 16> NewNodes;
+ for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
+ E = DAG.allnodes_end(); I != E; ++I) {
+ // Remember nodes marked NewNode - they are subject to extra checking below.
+ if (I->getNodeId() == NewNode)
+ NewNodes.push_back(I);
+
+ for (unsigned i = 0, e = I->getNumValues(); i != e; ++i) {
+ SDValue Res(I, i);
+ bool Failed = false;
+
+ unsigned Mapped = 0;
+ if (ReplacedValues.find(Res) != ReplacedValues.end()) {
+ Mapped |= 1;
+ // Check that remapped values are only used by nodes marked NewNode.
+ for (SDNode::use_iterator UI = I->use_begin(), UE = I->use_end();
+ UI != UE; ++UI)
+ if (UI.getUse().getResNo() == i)
+ assert(UI->getNodeId() == NewNode &&
+ "Remapped value has non-trivial use!");
+
+ // Check that the final result of applying ReplacedValues is not
+ // marked NewNode.
+ SDValue NewVal = ReplacedValues[Res];
+ DenseMap<SDValue, SDValue>::iterator I = ReplacedValues.find(NewVal);
+ while (I != ReplacedValues.end()) {
+ NewVal = I->second;
+ I = ReplacedValues.find(NewVal);
+ }
+ assert(NewVal.getNode()->getNodeId() != NewNode &&
+ "ReplacedValues maps to a new node!");
+ }
+ if (PromotedIntegers.find(Res) != PromotedIntegers.end())
+ Mapped |= 2;
+ if (SoftenedFloats.find(Res) != SoftenedFloats.end())
+ Mapped |= 4;
+ if (ScalarizedVectors.find(Res) != ScalarizedVectors.end())
+ Mapped |= 8;
+ if (ExpandedIntegers.find(Res) != ExpandedIntegers.end())
+ Mapped |= 16;
+ if (ExpandedFloats.find(Res) != ExpandedFloats.end())
+ Mapped |= 32;
+ if (SplitVectors.find(Res) != SplitVectors.end())
+ Mapped |= 64;
+ if (WidenedVectors.find(Res) != WidenedVectors.end())
+ Mapped |= 128;
+
+ if (I->getNodeId() != Processed) {
+ // Since we allow ReplacedValues to map deleted nodes, it may map nodes
+ // marked NewNode too, since a deleted node may have been reallocated as
+ // another node that has not been seen by the LegalizeTypes machinery.
+ if ((I->getNodeId() == NewNode && Mapped > 1) ||
+ (I->getNodeId() != NewNode && Mapped != 0)) {
+ dbgs() << "Unprocessed value in a map!";
+ Failed = true;
+ }
+ } else if (isTypeLegal(Res.getValueType()) || IgnoreNodeResults(I)) {
+ if (Mapped > 1) {
+ dbgs() << "Value with legal type was transformed!";
+ Failed = true;
+ }
+ } else {
+ if (Mapped == 0) {
+ dbgs() << "Processed value not in any map!";
+ Failed = true;
+ } else if (Mapped & (Mapped - 1)) {
+ dbgs() << "Value in multiple maps!";
+ Failed = true;
+ }
+ }
+
+ if (Failed) {
+ if (Mapped & 1)
+ dbgs() << " ReplacedValues";
+ if (Mapped & 2)
+ dbgs() << " PromotedIntegers";
+ if (Mapped & 4)
+ dbgs() << " SoftenedFloats";
+ if (Mapped & 8)
+ dbgs() << " ScalarizedVectors";
+ if (Mapped & 16)
+ dbgs() << " ExpandedIntegers";
+ if (Mapped & 32)
+ dbgs() << " ExpandedFloats";
+ if (Mapped & 64)
+ dbgs() << " SplitVectors";
+ if (Mapped & 128)
+ dbgs() << " WidenedVectors";
+ dbgs() << "\n";
+ llvm_unreachable(0);
+ }
+ }
+ }
+
+ // Checked that NewNodes are only used by other NewNodes.
+ for (unsigned i = 0, e = NewNodes.size(); i != e; ++i) {
+ SDNode *N = NewNodes[i];
+ for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
+ UI != UE; ++UI)
+ assert(UI->getNodeId() == NewNode && "NewNode used by non-NewNode!");
+ }
+}
+