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 switch (getTypeAction(ResultVT)) {
73 assert(false && "Unknown action!");
83 ScalarizeResult(N, i);
89 } while (++i < NumResults);
91 // Scan the operand list for the node, handling any nodes with operands that
94 unsigned NumOperands = N->getNumOperands();
95 bool NeedsRevisit = false;
96 for (i = 0; i != NumOperands; ++i) {
97 MVT::ValueType OpVT = N->getOperand(i).getValueType();
98 switch (getTypeAction(OpVT)) {
100 assert(false && "Unknown action!");
104 NeedsRevisit = PromoteOperand(N, i);
107 NeedsRevisit = ExpandOperand(N, i);
110 NeedsRevisit = ScalarizeOperand(N, i);
113 NeedsRevisit = SplitOperand(N, i);
119 // If the node needs revisiting, don't add all users to the worklist etc.
123 if (i == NumOperands)
124 DEBUG(cerr << "Legally typed node: "; N->dump(&DAG); cerr << "\n");
128 // If we reach here, the node was processed, potentially creating new nodes.
129 // Mark it as processed and add its users to the worklist as appropriate.
130 N->setNodeId(Processed);
132 for (SDNode::use_iterator UI = N->use_begin(), E = N->use_end();
135 int NodeID = User->getNodeId();
136 assert(NodeID != ReadyToProcess && NodeID != Processed &&
137 "Invalid node id for user of unprocessed node!");
139 // This node has two options: it can either be a new node or its Node ID
140 // may be a count of the number of operands it has that are not ready.
142 User->setNodeId(NodeID-1);
144 // If this was the last use it was waiting on, add it to the ready list.
145 if (NodeID-1 == ReadyToProcess)
146 Worklist.push_back(User);
150 // Otherwise, this node is new: this is the first operand of it that
151 // became ready. Its new NodeID is the number of operands it has minus 1
152 // (as this node is now processed).
153 assert(NodeID == NewNode && "Unknown node ID!");
154 User->setNodeId(User->getNumOperands()-1);
156 // If the node only has a single operand, it is now ready.
157 if (User->getNumOperands() == 1)
158 Worklist.push_back(User);
162 // If the root changed (e.g. it was a dead load, update the root).
163 DAG.setRoot(Dummy.getValue());
167 // Remove dead nodes. This is important to do for cleanliness but also before
168 // the checking loop below. Implicit folding by the DAG.getNode operators can
169 // cause unreachable nodes to be around with their flags set to new.
170 DAG.RemoveDeadNodes();
172 // In a debug build, scan all the nodes to make sure we found them all. This
173 // ensures that there are no cycles and that everything got processed.
175 for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
176 E = DAG.allnodes_end(); I != E; ++I) {
179 // Check that all result types are legal.
180 for (unsigned i = 0, NumVals = I->getNumValues(); i < NumVals; ++i)
181 if (!isTypeLegal(I->getValueType(i))) {
182 cerr << "Result type " << i << " illegal!\n";
186 // Check that all operand types are legal.
187 for (unsigned i = 0, NumOps = I->getNumOperands(); i < NumOps; ++i)
188 if (!isTypeLegal(I->getOperand(i).getValueType())) {
189 cerr << "Operand type " << i << " illegal!\n";
193 if (I->getNodeId() != Processed) {
194 if (I->getNodeId() == NewNode)
195 cerr << "New node not 'noticed'?\n";
196 else if (I->getNodeId() > 0)
197 cerr << "Operand not processed?\n";
198 else if (I->getNodeId() == ReadyToProcess)
199 cerr << "Not added to worklist?\n";
204 I->dump(&DAG); cerr << "\n";
211 /// AnalyzeNewNode - The specified node is the root of a subtree of potentially
212 /// new nodes. Correct any processed operands (this may change the node) and
213 /// calculate the NodeId.
214 void DAGTypeLegalizer::AnalyzeNewNode(SDNode *&N) {
215 // If this was an existing node that is already done, we're done.
216 if (N->getNodeId() != NewNode)
219 // Okay, we know that this node is new. Recursively walk all of its operands
220 // to see if they are new also. The depth of this walk is bounded by the size
221 // of the new tree that was constructed (usually 2-3 nodes), so we don't worry
222 // about revisiting of nodes.
224 // As we walk the operands, keep track of the number of nodes that are
225 // processed. If non-zero, this will become the new nodeid of this node.
226 // Already processed operands may need to be remapped to the node that
227 // replaced them, which can result in our node changing. Since remapping
228 // is rare, the code tries to minimize overhead in the non-remapping case.
230 SmallVector<SDOperand, 8> NewOps;
231 unsigned NumProcessed = 0;
232 for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
233 SDOperand OrigOp = N->getOperand(i);
234 SDOperand Op = OrigOp;
236 if (Op.Val->getNodeId() == Processed)
239 if (Op.Val->getNodeId() == NewNode)
240 AnalyzeNewNode(Op.Val);
241 else if (Op.Val->getNodeId() == Processed)
244 if (!NewOps.empty()) {
245 // Some previous operand changed. Add this one to the list.
246 NewOps.push_back(Op);
247 } else if (Op != OrigOp) {
248 // This is the first operand to change - add all operands so far.
249 for (unsigned j = 0; j < i; ++j)
250 NewOps.push_back(N->getOperand(j));
251 NewOps.push_back(Op);
255 // Some operands changed - update the node.
257 N = DAG.UpdateNodeOperands(SDOperand(N, 0), &NewOps[0], NewOps.size()).Val;
259 N->setNodeId(N->getNumOperands()-NumProcessed);
260 if (N->getNodeId() == ReadyToProcess)
261 Worklist.push_back(N);
265 /// NodeUpdateListener - This class is a DAGUpdateListener that listens for
266 /// updates to nodes and recomputes their ready state.
267 class VISIBILITY_HIDDEN NodeUpdateListener :
268 public SelectionDAG::DAGUpdateListener {
269 DAGTypeLegalizer &DTL;
271 NodeUpdateListener(DAGTypeLegalizer &dtl) : DTL(dtl) {}
273 virtual void NodeDeleted(SDNode *N) {
275 assert(N->getNodeId() != DAGTypeLegalizer::Processed &&
276 N->getNodeId() != DAGTypeLegalizer::ReadyToProcess &&
277 "RAUW deleted processed node!");
280 virtual void NodeUpdated(SDNode *N) {
281 // Node updates can mean pretty much anything. It is possible that an
282 // operand was set to something already processed (f.e.) in which case
283 // this node could become ready. Recompute its flags.
284 assert(N->getNodeId() != DAGTypeLegalizer::Processed &&
285 N->getNodeId() != DAGTypeLegalizer::ReadyToProcess &&
286 "RAUW updated processed node!");
287 DTL.ReanalyzeNode(N);
293 /// ReplaceValueWith - The specified value was legalized to the specified other
294 /// value. If they are different, update the DAG and NodeIDs replacing any uses
295 /// of From to use To instead.
296 void DAGTypeLegalizer::ReplaceValueWith(SDOperand From, SDOperand To) {
297 if (From == To) return;
299 // If expansion produced new nodes, make sure they are properly marked.
300 AnalyzeNewNode(To.Val);
302 // Anything that used the old node should now use the new one. Note that this
303 // can potentially cause recursive merging.
304 NodeUpdateListener NUL(*this);
305 DAG.ReplaceAllUsesOfValueWith(From, To, &NUL);
307 // The old node may still be present in ExpandedNodes or PromotedNodes.
308 // Inform them about the replacement.
309 ReplacedNodes[From] = To;
312 /// ReplaceNodeWith - Replace uses of the 'from' node's results with the 'to'
313 /// node's results. The from and to node must define identical result types.
314 void DAGTypeLegalizer::ReplaceNodeWith(SDNode *From, SDNode *To) {
315 if (From == To) return;
317 // If expansion produced new nodes, make sure they are properly marked.
320 assert(From->getNumValues() == To->getNumValues() &&
321 "Node results don't match");
323 // Anything that used the old node should now use the new one. Note that this
324 // can potentially cause recursive merging.
325 NodeUpdateListener NUL(*this);
326 DAG.ReplaceAllUsesWith(From, To, &NUL);
328 // The old node may still be present in ExpandedNodes or PromotedNodes.
329 // Inform them about the replacement.
330 for (unsigned i = 0, e = From->getNumValues(); i != e; ++i) {
331 assert(From->getValueType(i) == To->getValueType(i) &&
332 "Node results don't match");
333 ReplacedNodes[SDOperand(From, i)] = SDOperand(To, i);
338 /// RemapNode - If the specified value was already legalized to another value,
339 /// replace it by that value.
340 void DAGTypeLegalizer::RemapNode(SDOperand &N) {
341 DenseMap<SDOperand, SDOperand>::iterator I = ReplacedNodes.find(N);
342 if (I != ReplacedNodes.end()) {
343 // Use path compression to speed up future lookups if values get multiply
344 // replaced with other values.
345 RemapNode(I->second);
350 void DAGTypeLegalizer::SetPromotedOp(SDOperand Op, SDOperand Result) {
351 AnalyzeNewNode(Result.Val);
353 SDOperand &OpEntry = PromotedNodes[Op];
354 assert(OpEntry.Val == 0 && "Node is already promoted!");
358 void DAGTypeLegalizer::SetScalarizedOp(SDOperand Op, SDOperand Result) {
359 AnalyzeNewNode(Result.Val);
361 SDOperand &OpEntry = ScalarizedNodes[Op];
362 assert(OpEntry.Val == 0 && "Node is already scalarized!");
367 void DAGTypeLegalizer::GetExpandedOp(SDOperand Op, SDOperand &Lo,
369 std::pair<SDOperand, SDOperand> &Entry = ExpandedNodes[Op];
370 RemapNode(Entry.first);
371 RemapNode(Entry.second);
372 assert(Entry.first.Val && "Operand isn't expanded");
377 void DAGTypeLegalizer::SetExpandedOp(SDOperand Op, SDOperand Lo, SDOperand Hi) {
378 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant.
379 AnalyzeNewNode(Lo.Val);
380 AnalyzeNewNode(Hi.Val);
382 // Remember that this is the result of the node.
383 std::pair<SDOperand, SDOperand> &Entry = ExpandedNodes[Op];
384 assert(Entry.first.Val == 0 && "Node already expanded");
389 void DAGTypeLegalizer::GetSplitOp(SDOperand Op, SDOperand &Lo, SDOperand &Hi) {
390 std::pair<SDOperand, SDOperand> &Entry = SplitNodes[Op];
391 RemapNode(Entry.first);
392 RemapNode(Entry.second);
393 assert(Entry.first.Val && "Operand isn't split");
398 void DAGTypeLegalizer::SetSplitOp(SDOperand Op, SDOperand Lo, SDOperand Hi) {
399 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant.
400 AnalyzeNewNode(Lo.Val);
401 AnalyzeNewNode(Hi.Val);
403 // Remember that this is the result of the node.
404 std::pair<SDOperand, SDOperand> &Entry = SplitNodes[Op];
405 assert(Entry.first.Val == 0 && "Node already split");
411 SDOperand DAGTypeLegalizer::CreateStackStoreLoad(SDOperand Op,
412 MVT::ValueType DestVT) {
413 // Create the stack frame object.
414 SDOperand FIPtr = DAG.CreateStackTemporary(DestVT);
416 // Emit a store to the stack slot.
417 SDOperand Store = DAG.getStore(DAG.getEntryNode(), Op, FIPtr, NULL, 0);
418 // Result is a load from the stack slot.
419 return DAG.getLoad(DestVT, Store, FIPtr, NULL, 0);
422 /// HandleMemIntrinsic - This handles memcpy/memset/memmove with invalid
423 /// operands. This promotes or expands the operands as required.
424 SDOperand DAGTypeLegalizer::HandleMemIntrinsic(SDNode *N) {
425 // The chain and pointer [operands #0 and #1] are always valid types.
426 SDOperand Chain = N->getOperand(0);
427 SDOperand Ptr = N->getOperand(1);
428 SDOperand Op2 = N->getOperand(2);
430 // Op #2 is either a value (memset) or a pointer. Promote it if required.
431 switch (getTypeAction(Op2.getValueType())) {
432 default: assert(0 && "Unknown action for pointer/value operand");
434 case Promote: Op2 = GetPromotedOp(Op2); break;
437 // The length could have any action required.
438 SDOperand Length = N->getOperand(3);
439 switch (getTypeAction(Length.getValueType())) {
440 default: assert(0 && "Unknown action for memop operand");
442 case Promote: Length = GetPromotedZExtOp(Length); break;
444 SDOperand Dummy; // discard the high part.
445 GetExpandedOp(Length, Length, Dummy);
449 SDOperand Align = N->getOperand(4);
450 switch (getTypeAction(Align.getValueType())) {
451 default: assert(0 && "Unknown action for memop operand");
453 case Promote: Align = GetPromotedZExtOp(Align); break;
456 SDOperand AlwaysInline = N->getOperand(5);
457 switch (getTypeAction(AlwaysInline.getValueType())) {
458 default: assert(0 && "Unknown action for memop operand");
460 case Promote: AlwaysInline = GetPromotedZExtOp(AlwaysInline); break;
463 SDOperand Ops[] = { Chain, Ptr, Op2, Length, Align, AlwaysInline };
464 return DAG.UpdateNodeOperands(SDOperand(N, 0), Ops, 6);
467 /// SplitOp - Return the lower and upper halves of Op's bits in a value type
468 /// half the size of Op's.
469 void DAGTypeLegalizer::SplitOp(SDOperand Op, SDOperand &Lo, SDOperand &Hi) {
470 unsigned NVTBits = MVT::getSizeInBits(Op.getValueType())/2;
471 assert(MVT::getSizeInBits(Op.getValueType()) == 2*NVTBits &&
472 "Cannot split odd sized integer type");
473 MVT::ValueType NVT = MVT::getIntegerType(NVTBits);
474 Lo = DAG.getNode(ISD::TRUNCATE, NVT, Op);
475 Hi = DAG.getNode(ISD::SRL, Op.getValueType(), Op,
476 DAG.getConstant(NVTBits, TLI.getShiftAmountTy()));
477 Hi = DAG.getNode(ISD::TRUNCATE, NVT, Hi);
481 //===----------------------------------------------------------------------===//
483 //===----------------------------------------------------------------------===//
485 /// LegalizeTypes - This transforms the SelectionDAG into a SelectionDAG that
486 /// only uses types natively supported by the target.
488 /// Note that this is an involved process that may invalidate pointers into
490 void SelectionDAG::LegalizeTypes() {
491 if (ViewLegalizeTypesDAGs) viewGraph();
493 DAGTypeLegalizer(*this).run();