1 //===-- LegalizeTypes.cpp - Common code for DAG type legalizer ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the SelectionDAG::LegalizeTypes method. It transforms
11 // an arbitrary well-formed SelectionDAG to only consist of legal types. This
12 // is common code shared among the LegalizeTypes*.cpp files.
14 //===----------------------------------------------------------------------===//
16 #include "LegalizeTypes.h"
17 #include "llvm/Constants.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/Support/MathExtras.h"
25 ViewLegalizeTypesDAGs("view-legalize-types-dags", cl::Hidden,
26 cl::desc("Pop up a window to show dags before legalize types"));
28 static const bool ViewLegalizeTypesDAGs = 0;
33 /// run - This is the main entry point for the type legalizer. This does a
34 /// top-down traversal of the dag, legalizing types as it goes.
35 void DAGTypeLegalizer::run() {
36 // Create a dummy node (which is not added to allnodes), that adds a reference
37 // to the root node, preventing it from being deleted, and tracking any
38 // changes of the root.
39 HandleSDNode Dummy(DAG.getRoot());
41 // The root of the dag may dangle to deleted nodes until the type legalizer is
42 // done. Set it to null to avoid confusion.
43 DAG.setRoot(SDOperand());
45 // Walk all nodes in the graph, assigning them a NodeID of 'ReadyToProcess'
46 // (and remembering them) if they are leaves and assigning 'NewNode' if
48 for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
49 E = DAG.allnodes_end(); I != E; ++I) {
50 if (I->getNumOperands() == 0) {
51 I->setNodeId(ReadyToProcess);
52 Worklist.push_back(I);
54 I->setNodeId(NewNode);
58 // Now that we have a set of nodes to process, handle them all.
59 while (!Worklist.empty()) {
60 SDNode *N = Worklist.back();
62 assert(N->getNodeId() == ReadyToProcess &&
63 "Node should be ready if on worklist!");
65 // Scan the values produced by the node, checking to see if any result
68 unsigned NumResults = N->getNumValues();
70 MVT::ValueType ResultVT = N->getValueType(i);
71 LegalizeAction Action = getTypeAction(ResultVT);
72 if (Action == Promote) {
75 } else if (Action == Expand) {
76 // Expand can mean 1) split integer in half 2) scalarize single-element
77 // vector 3) split vector in half.
78 if (!MVT::isVector(ResultVT))
80 else if (MVT::getVectorNumElements(ResultVT) == 1)
81 ScalarizeResult(N, i); // Scalarize the single-element vector.
83 SplitResult(N, i); // Split the vector in half.
86 assert(Action == Legal && "Unknown action!");
88 } while (++i < NumResults);
90 // Scan the operand list for the node, handling any nodes with operands that
93 unsigned NumOperands = N->getNumOperands();
94 bool NeedsRevisit = false;
95 for (i = 0; i != NumOperands; ++i) {
96 MVT::ValueType OpVT = N->getOperand(i).getValueType();
97 LegalizeAction Action = getTypeAction(OpVT);
98 if (Action == Promote) {
99 NeedsRevisit = PromoteOperand(N, i);
101 } else if (Action == Expand) {
102 // Expand can mean 1) split integer in half 2) scalarize single-element
103 // vector 3) split vector in half.
104 if (!MVT::isVector(OpVT)) {
105 NeedsRevisit = ExpandOperand(N, i);
106 } else if (MVT::getVectorNumElements(OpVT) == 1) {
107 // Scalarize the single-element vector.
108 NeedsRevisit = ScalarizeOperand(N, i);
110 NeedsRevisit = SplitOperand(N, i); // Split the vector in half.
114 assert(Action == Legal && "Unknown action!");
118 // If the node needs revisiting, don't add all users to the worklist etc.
122 if (i == NumOperands)
123 DEBUG(cerr << "Legally typed node: "; N->dump(&DAG); cerr << "\n");
127 // If we reach here, the node was processed, potentially creating new nodes.
128 // Mark it as processed and add its users to the worklist as appropriate.
129 N->setNodeId(Processed);
131 for (SDNode::use_iterator UI = N->use_begin(), E = N->use_end();
134 int NodeID = User->getNodeId();
135 assert(NodeID != ReadyToProcess && NodeID != Processed &&
136 "Invalid node id for user of unprocessed node!");
138 // This node has two options: it can either be a new node or its Node ID
139 // may be a count of the number of operands it has that are not ready.
141 User->setNodeId(NodeID-1);
143 // If this was the last use it was waiting on, add it to the ready list.
144 if (NodeID-1 == ReadyToProcess)
145 Worklist.push_back(User);
149 // Otherwise, this node is new: this is the first operand of it that
150 // became ready. Its new NodeID is the number of operands it has minus 1
151 // (as this node is now processed).
152 assert(NodeID == NewNode && "Unknown node ID!");
153 User->setNodeId(User->getNumOperands()-1);
155 // If the node only has a single operand, it is now ready.
156 if (User->getNumOperands() == 1)
157 Worklist.push_back(User);
161 // If the root changed (e.g. it was a dead load, update the root).
162 DAG.setRoot(Dummy.getValue());
166 // Remove dead nodes. This is important to do for cleanliness but also before
167 // the checking loop below. Implicit folding by the DAG.getNode operators can
168 // cause unreachable nodes to be around with their flags set to new.
169 DAG.RemoveDeadNodes();
171 // In a debug build, scan all the nodes to make sure we found them all. This
172 // ensures that there are no cycles and that everything got processed.
174 for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
175 E = DAG.allnodes_end(); I != E; ++I) {
176 if (I->getNodeId() == Processed)
178 cerr << "Unprocessed node: ";
179 I->dump(&DAG); cerr << "\n";
181 if (I->getNodeId() == NewNode)
182 cerr << "New node not 'noticed'?\n";
183 else if (I->getNodeId() > 0)
184 cerr << "Operand not processed?\n";
185 else if (I->getNodeId() == ReadyToProcess)
186 cerr << "Not added to worklist?\n";
192 /// MarkNewNodes - The specified node is the root of a subtree of potentially
193 /// new nodes. Add the correct NodeId to mark it.
194 void DAGTypeLegalizer::MarkNewNodes(SDNode *N) {
195 // If this was an existing node that is already done, we're done.
196 if (N->getNodeId() != NewNode)
199 // Okay, we know that this node is new. Recursively walk all of its operands
200 // to see if they are new also. The depth of this walk is bounded by the size
201 // of the new tree that was constructed (usually 2-3 nodes), so we don't worry
202 // about revisiting of nodes.
204 // As we walk the operands, keep track of the number of nodes that are
205 // processed. If non-zero, this will become the new nodeid of this node.
206 unsigned NumProcessed = 0;
207 for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
208 int OpId = N->getOperand(i).Val->getNodeId();
210 MarkNewNodes(N->getOperand(i).Val);
211 else if (OpId == Processed)
215 N->setNodeId(N->getNumOperands()-NumProcessed);
216 if (N->getNodeId() == ReadyToProcess)
217 Worklist.push_back(N);
220 /// ReplaceValueWith - The specified value was legalized to the specified other
221 /// value. If they are different, update the DAG and NodeIDs replacing any uses
222 /// of From to use To instead.
223 void DAGTypeLegalizer::ReplaceValueWith(SDOperand From, SDOperand To) {
224 if (From == To) return;
226 // If expansion produced new nodes, make sure they are properly marked.
227 if (To.Val->getNodeId() == NewNode)
228 MarkNewNodes(To.Val);
230 // Anything that used the old node should now use the new one. Note that this
231 // can potentially cause recursive merging.
232 DAG.ReplaceAllUsesOfValueWith(From, To);
234 // The old node may still be present in ExpandedNodes or PromotedNodes.
235 // Inform them about the replacement.
236 ReplacedNodes[From] = To;
238 // Since we just made an unstructured update to the DAG, which could wreak
239 // general havoc on anything that once used From and now uses To, walk all
240 // users of the result, updating their flags.
241 for (SDNode::use_iterator I = To.Val->use_begin(), E = To.Val->use_end();
244 // If the node isn't already processed or in the worklist, mark it as new,
245 // then use MarkNewNodes to recompute its ID.
246 int NodeId = User->getNodeId();
247 if (NodeId != ReadyToProcess && NodeId != Processed) {
248 User->setNodeId(NewNode);
254 /// ReplaceNodeWith - Replace uses of the 'from' node's results with the 'to'
255 /// node's results. The from and to node must define identical result types.
256 void DAGTypeLegalizer::ReplaceNodeWith(SDNode *From, SDNode *To) {
257 if (From == To) return;
258 assert(From->getNumValues() == To->getNumValues() &&
259 "Node results don't match");
261 // If expansion produced new nodes, make sure they are properly marked.
262 if (To->getNodeId() == NewNode)
265 // Anything that used the old node should now use the new one. Note that this
266 // can potentially cause recursive merging.
267 DAG.ReplaceAllUsesWith(From, To);
269 // The old node may still be present in ExpandedNodes or PromotedNodes.
270 // Inform them about the replacement.
271 for (unsigned i = 0, e = From->getNumValues(); i != e; ++i) {
272 assert(From->getValueType(i) == To->getValueType(i) &&
273 "Node results don't match");
274 ReplacedNodes[SDOperand(From, i)] = SDOperand(To, i);
277 // Since we just made an unstructured update to the DAG, which could wreak
278 // general havoc on anything that once used From and now uses To, walk all
279 // users of the result, updating their flags.
280 for (SDNode::use_iterator I = To->use_begin(), E = To->use_end();I != E; ++I){
282 // If the node isn't already processed or in the worklist, mark it as new,
283 // then use MarkNewNodes to recompute its ID.
284 int NodeId = User->getNodeId();
285 if (NodeId != ReadyToProcess && NodeId != Processed) {
286 User->setNodeId(NewNode);
293 /// RemapNode - If the specified value was already legalized to another value,
294 /// replace it by that value.
295 void DAGTypeLegalizer::RemapNode(SDOperand &N) {
296 DenseMap<SDOperand, SDOperand>::iterator I = ReplacedNodes.find(N);
297 if (I != ReplacedNodes.end()) {
298 // Use path compression to speed up future lookups if values get multiply
299 // replaced with other values.
300 RemapNode(I->second);
305 void DAGTypeLegalizer::SetPromotedOp(SDOperand Op, SDOperand Result) {
306 if (Result.Val->getNodeId() == NewNode)
307 MarkNewNodes(Result.Val);
309 SDOperand &OpEntry = PromotedNodes[Op];
310 assert(OpEntry.Val == 0 && "Node is already promoted!");
314 void DAGTypeLegalizer::SetScalarizedOp(SDOperand Op, SDOperand Result) {
315 if (Result.Val->getNodeId() == NewNode)
316 MarkNewNodes(Result.Val);
318 SDOperand &OpEntry = ScalarizedNodes[Op];
319 assert(OpEntry.Val == 0 && "Node is already scalarized!");
324 void DAGTypeLegalizer::GetExpandedOp(SDOperand Op, SDOperand &Lo,
326 std::pair<SDOperand, SDOperand> &Entry = ExpandedNodes[Op];
327 RemapNode(Entry.first);
328 RemapNode(Entry.second);
329 assert(Entry.first.Val && "Operand isn't expanded");
334 void DAGTypeLegalizer::SetExpandedOp(SDOperand Op, SDOperand Lo, SDOperand Hi) {
335 // Remember that this is the result of the node.
336 std::pair<SDOperand, SDOperand> &Entry = ExpandedNodes[Op];
337 assert(Entry.first.Val == 0 && "Node already expanded");
341 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant.
342 if (Lo.Val->getNodeId() == NewNode)
343 MarkNewNodes(Lo.Val);
344 if (Hi.Val->getNodeId() == NewNode)
345 MarkNewNodes(Hi.Val);
348 void DAGTypeLegalizer::GetSplitOp(SDOperand Op, SDOperand &Lo, SDOperand &Hi) {
349 std::pair<SDOperand, SDOperand> &Entry = SplitNodes[Op];
350 RemapNode(Entry.first);
351 RemapNode(Entry.second);
352 assert(Entry.first.Val && "Operand isn't split");
357 void DAGTypeLegalizer::SetSplitOp(SDOperand Op, SDOperand Lo, SDOperand Hi) {
358 // Remember that this is the result of the node.
359 std::pair<SDOperand, SDOperand> &Entry = SplitNodes[Op];
360 assert(Entry.first.Val == 0 && "Node already split");
364 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant.
365 if (Lo.Val->getNodeId() == NewNode)
366 MarkNewNodes(Lo.Val);
367 if (Hi.Val->getNodeId() == NewNode)
368 MarkNewNodes(Hi.Val);
372 SDOperand DAGTypeLegalizer::CreateStackStoreLoad(SDOperand Op,
373 MVT::ValueType DestVT) {
374 // Create the stack frame object.
375 SDOperand FIPtr = DAG.CreateStackTemporary(DestVT);
377 // Emit a store to the stack slot.
378 SDOperand Store = DAG.getStore(DAG.getEntryNode(), Op, FIPtr, NULL, 0);
379 // Result is a load from the stack slot.
380 return DAG.getLoad(DestVT, Store, FIPtr, NULL, 0);
383 /// HandleMemIntrinsic - This handles memcpy/memset/memmove with invalid
384 /// operands. This promotes or expands the operands as required.
385 SDOperand DAGTypeLegalizer::HandleMemIntrinsic(SDNode *N) {
386 // The chain and pointer [operands #0 and #1] are always valid types.
387 SDOperand Chain = N->getOperand(0);
388 SDOperand Ptr = N->getOperand(1);
389 SDOperand Op2 = N->getOperand(2);
391 // Op #2 is either a value (memset) or a pointer. Promote it if required.
392 switch (getTypeAction(Op2.getValueType())) {
393 default: assert(0 && "Unknown action for pointer/value operand");
395 case Promote: Op2 = GetPromotedOp(Op2); break;
398 // The length could have any action required.
399 SDOperand Length = N->getOperand(3);
400 switch (getTypeAction(Length.getValueType())) {
401 default: assert(0 && "Unknown action for memop operand");
403 case Promote: Length = GetPromotedZExtOp(Length); break;
405 SDOperand Dummy; // discard the high part.
406 GetExpandedOp(Length, Length, Dummy);
410 SDOperand Align = N->getOperand(4);
411 switch (getTypeAction(Align.getValueType())) {
412 default: assert(0 && "Unknown action for memop operand");
414 case Promote: Align = GetPromotedZExtOp(Align); break;
417 SDOperand AlwaysInline = N->getOperand(5);
418 switch (getTypeAction(AlwaysInline.getValueType())) {
419 default: assert(0 && "Unknown action for memop operand");
421 case Promote: AlwaysInline = GetPromotedZExtOp(AlwaysInline); break;
424 SDOperand Ops[] = { Chain, Ptr, Op2, Length, Align, AlwaysInline };
425 return DAG.UpdateNodeOperands(SDOperand(N, 0), Ops, 6);
428 /// SplitOp - Return the lower and upper halves of Op's bits in a value type
429 /// half the size of Op's.
430 void DAGTypeLegalizer::SplitOp(SDOperand Op, SDOperand &Lo, SDOperand &Hi) {
431 unsigned NVTBits = MVT::getSizeInBits(Op.getValueType())/2;
432 assert(MVT::getSizeInBits(Op.getValueType()) == 2*NVTBits &&
433 "Cannot split odd sized integer type");
434 MVT::ValueType NVT = MVT::getIntegerType(NVTBits);
435 Lo = DAG.getNode(ISD::TRUNCATE, NVT, Op);
436 Hi = DAG.getNode(ISD::SRL, Op.getValueType(), Op,
437 DAG.getConstant(NVTBits, TLI.getShiftAmountTy()));
438 Hi = DAG.getNode(ISD::TRUNCATE, NVT, Hi);
442 //===----------------------------------------------------------------------===//
444 //===----------------------------------------------------------------------===//
446 /// LegalizeTypes - This transforms the SelectionDAG into a SelectionDAG that
447 /// only uses types natively supported by the target.
449 /// Note that this is an involved process that may invalidate pointers into
451 void SelectionDAG::LegalizeTypes() {
452 if (ViewLegalizeTypesDAGs) viewGraph();
454 DAGTypeLegalizer(*this).run();