SSAUpdater.cpp revision 867be59684afef29f058385c6618ec7753596ffc
193f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner//===- SSAUpdater.cpp - Unstructured SSA Update Tool ----------------------===// 293f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// 393f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// The LLVM Compiler Infrastructure 493f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// 593f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// This file is distributed under the University of Illinois Open Source 693f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// License. See LICENSE.TXT for details. 793f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// 893f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner//===----------------------------------------------------------------------===// 993f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// 1093f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// This file implements the SSAUpdater class. 1193f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner// 1293f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner//===----------------------------------------------------------------------===// 1393f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 1484bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson#define DEBUG_TYPE "ssaupdater" 1593f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner#include "llvm/Instructions.h" 1693f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner#include "llvm/ADT/DenseMap.h" 17cdbd99262286e96729007ac535cd430ecb3d38acDuncan Sands#include "llvm/Analysis/InstructionSimplify.h" 1884bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson#include "llvm/Support/AlignOf.h" 1984bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson#include "llvm/Support/Allocator.h" 2093f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner#include "llvm/Support/CFG.h" 2193f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner#include "llvm/Support/Debug.h" 2293f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner#include "llvm/Support/raw_ostream.h" 234aad88d1fd88413029dd05255306b07cb19396eeBob Wilson#include "llvm/Transforms/Utils/SSAUpdater.h" 244aad88d1fd88413029dd05255306b07cb19396eeBob Wilson#include "llvm/Transforms/Utils/SSAUpdaterImpl.h" 2593f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattnerusing namespace llvm; 2693f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 2784bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilsontypedef DenseMap<BasicBlock*, Value*> AvailableValsTy; 2893f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattnerstatic AvailableValsTy &getAvailableVals(void *AV) { 2993f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner return *static_cast<AvailableValsTy*>(AV); 3093f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner} 3193f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 32f5a1fb6b247611b92d9dec9476202b477661dbe8Chris LattnerSSAUpdater::SSAUpdater(SmallVectorImpl<PHINode*> *NewPHI) 33fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands : AV(0), ProtoType(0), ProtoName(), InsertedPHIs(NewPHI) {} 3493f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 3593f3bcf7f323069e40d9abb950da73d437b6f7daChris LattnerSSAUpdater::~SSAUpdater() { 3693f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner delete &getAvailableVals(AV); 3793f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner} 3893f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 3993f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner/// Initialize - Reset this object to get ready for a new set of SSA 40fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands/// updates with type 'Ty'. PHI nodes get a name based on 'Name'. 41fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sandsvoid SSAUpdater::Initialize(const Type *Ty, StringRef Name) { 4293f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner if (AV == 0) 4393f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner AV = new AvailableValsTy(); 4493f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner else 4593f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner getAvailableVals(AV).clear(); 46fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands ProtoType = Ty; 47fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands ProtoName = Name; 4893f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner} 4993f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 500bef562ea253878ee92a1eaf6db05b0c2edfa74cChris Lattner/// HasValueForBlock - Return true if the SSAUpdater already has a value for 510bef562ea253878ee92a1eaf6db05b0c2edfa74cChris Lattner/// the specified block. 520bef562ea253878ee92a1eaf6db05b0c2edfa74cChris Lattnerbool SSAUpdater::HasValueForBlock(BasicBlock *BB) const { 530bef562ea253878ee92a1eaf6db05b0c2edfa74cChris Lattner return getAvailableVals(AV).count(BB); 540bef562ea253878ee92a1eaf6db05b0c2edfa74cChris Lattner} 550bef562ea253878ee92a1eaf6db05b0c2edfa74cChris Lattner 5693f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner/// AddAvailableValue - Indicate that a rewritten value is available in the 5793f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner/// specified block with the specified value. 5893f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattnervoid SSAUpdater::AddAvailableValue(BasicBlock *BB, Value *V) { 59fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands assert(ProtoType != 0 && "Need to initialize SSAUpdater"); 60fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands assert(ProtoType == V->getType() && 6193f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner "All rewritten values must have the same type"); 6293f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner getAvailableVals(AV)[BB] = V; 6393f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner} 6493f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 65e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson/// IsEquivalentPHI - Check if PHI has the same incoming value as specified 66e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson/// in ValueMapping for each predecessor block. 6784bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilsonstatic bool IsEquivalentPHI(PHINode *PHI, 68e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson DenseMap<BasicBlock*, Value*> &ValueMapping) { 69e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson unsigned PHINumValues = PHI->getNumIncomingValues(); 70e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson if (PHINumValues != ValueMapping.size()) 71e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson return false; 72e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson 73e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson // Scan the phi to see if it matches. 74e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson for (unsigned i = 0, e = PHINumValues; i != e; ++i) 75e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson if (ValueMapping[PHI->getIncomingBlock(i)] != 76e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson PHI->getIncomingValue(i)) { 77e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson return false; 78e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson } 79e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson 80e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson return true; 81e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson} 82e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson 831a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is 841a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// live at the end of the specified block. 855fb107287fd8d35b8fc39aa3e6b084fb2871a8ffChris LattnerValue *SSAUpdater::GetValueAtEndOfBlock(BasicBlock *BB) { 865fb107287fd8d35b8fc39aa3e6b084fb2871a8ffChris Lattner Value *Res = GetValueAtEndOfBlockInternal(BB); 8793f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner return Res; 8893f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner} 8993f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 901a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// GetValueInMiddleOfBlock - Construct SSA form, materializing a value that 911a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// is live in the middle of the specified block. 921a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// 931a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// GetValueInMiddleOfBlock is the same as GetValueAtEndOfBlock except in one 941a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// important case: if there is a definition of the rewritten value after the 951a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// 'use' in BB. Consider code like this: 961a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// 971a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// X1 = ... 981a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// SomeBB: 991a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// use(X) 1001a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// X2 = ... 1011a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// br Cond, SomeBB, OutBB 1021a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// 1031a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// In this case, there are two values (X1 and X2) added to the AvailableVals 1041a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// set by the client of the rewriter, and those values are both live out of 1051a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// their respective blocks. However, the use of X happens in the *middle* of 1061a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// a block. Because of this, we need to insert a new PHI node in SomeBB to 1071a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// merge the appropriate values, and this value isn't live out of the block. 1081a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner/// 1091a8d4de397c360a76f1389d15e862eba265d71fdChris LattnerValue *SSAUpdater::GetValueInMiddleOfBlock(BasicBlock *BB) { 1101a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // If there is no definition of the renamed variable in this block, just use 1111a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // GetValueAtEndOfBlock to do our work. 11284bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson if (!HasValueForBlock(BB)) 1131a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner return GetValueAtEndOfBlock(BB); 114ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1151a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // Otherwise, we have the hard case. Get the live-in values for each 1161a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // predecessor. 1171a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner SmallVector<std::pair<BasicBlock*, Value*>, 8> PredValues; 1181a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner Value *SingularValue = 0; 119ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1201a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // We can get our predecessor info by walking the pred_iterator list, but it 1211a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // is relatively slow. If we already have PHI nodes in this block, walk one 1221a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // of them to get the predecessor list instead. 1231a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner if (PHINode *SomePhi = dyn_cast<PHINode>(BB->begin())) { 1241a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner for (unsigned i = 0, e = SomePhi->getNumIncomingValues(); i != e; ++i) { 1251a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner BasicBlock *PredBB = SomePhi->getIncomingBlock(i); 1261a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner Value *PredVal = GetValueAtEndOfBlock(PredBB); 1271a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner PredValues.push_back(std::make_pair(PredBB, PredVal)); 128ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1291a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // Compute SingularValue. 1301a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner if (i == 0) 1311a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner SingularValue = PredVal; 1321a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner else if (PredVal != SingularValue) 1331a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner SingularValue = 0; 1341a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner } 1351a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner } else { 1361a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner bool isFirstPred = true; 1371a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 1381a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner BasicBlock *PredBB = *PI; 1391a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner Value *PredVal = GetValueAtEndOfBlock(PredBB); 1401a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner PredValues.push_back(std::make_pair(PredBB, PredVal)); 141ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1421a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // Compute SingularValue. 1431a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner if (isFirstPred) { 1441a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner SingularValue = PredVal; 1451a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner isFirstPred = false; 1461a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner } else if (PredVal != SingularValue) 1471a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner SingularValue = 0; 1481a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner } 1491a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner } 150ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1511a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // If there are no predecessors, just return undef. 1521a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner if (PredValues.empty()) 153fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands return UndefValue::get(ProtoType); 154ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1551a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // Otherwise, if all the merged values are the same, just use it. 1561a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner if (SingularValue != 0) 1571a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner return SingularValue; 158ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 15984bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson // Otherwise, we do need a PHI: check to see if we already have one available 16084bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson // in this block that produces the right value. 16184bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson if (isa<PHINode>(BB->begin())) { 16284bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson DenseMap<BasicBlock*, Value*> ValueMapping(PredValues.begin(), 16384bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson PredValues.end()); 16484bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson PHINode *SomePHI; 16584bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson for (BasicBlock::iterator It = BB->begin(); 16684bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson (SomePHI = dyn_cast<PHINode>(It)); ++It) { 16784bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson if (IsEquivalentPHI(SomePHI, ValueMapping)) 16884bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson return SomePHI; 16984bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 17084bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 171e98585eb36eff3b8c7da1cf7b044da6a05973074Bob Wilson 1724c1e3da0cdd2fd0df5188dea1988beb8bf6a0dc6Chris Lattner // Ok, we have no way out, insert a new one now. 173fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands PHINode *InsertedPHI = PHINode::Create(ProtoType, ProtoName, &BB->front()); 1741a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner InsertedPHI->reserveOperandSpace(PredValues.size()); 175ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1761a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // Fill in all the predecessors of the PHI. 1771a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner for (unsigned i = 0, e = PredValues.size(); i != e; ++i) 1781a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner InsertedPHI->addIncoming(PredValues[i].second, PredValues[i].first); 179ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1801a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // See if the PHI node can be merged to a single value. This can happen in 1811a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner // loop cases when we get a PHI of itself and one other value. 182cdbd99262286e96729007ac535cd430ecb3d38acDuncan Sands if (Value *V = SimplifyInstruction(InsertedPHI)) { 1831a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner InsertedPHI->eraseFromParent(); 184cdbd99262286e96729007ac535cd430ecb3d38acDuncan Sands return V; 1851a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner } 186f5a1fb6b247611b92d9dec9476202b477661dbe8Chris Lattner 187f5a1fb6b247611b92d9dec9476202b477661dbe8Chris Lattner // If the client wants to know about all new instructions, tell it. 188f5a1fb6b247611b92d9dec9476202b477661dbe8Chris Lattner if (InsertedPHIs) InsertedPHIs->push_back(InsertedPHI); 189ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 1901af40cacd4d162ffe9dfbafa1230e502e059be65David Greene DEBUG(dbgs() << " Inserted PHI: " << *InsertedPHI << "\n"); 1911a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner return InsertedPHI; 1921a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner} 1931a8d4de397c360a76f1389d15e862eba265d71fdChris Lattner 19493f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner/// RewriteUse - Rewrite a use of the symbolic value. This handles PHI nodes, 19593f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner/// which use their value in the corresponding predecessor. 19693f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattnervoid SSAUpdater::RewriteUse(Use &U) { 19793f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner Instruction *User = cast<Instruction>(U.getUser()); 19884bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson 19988a8624f8e104e1ba1ca21efa6ae23680b528a3eChris Lattner Value *V; 20088a8624f8e104e1ba1ca21efa6ae23680b528a3eChris Lattner if (PHINode *UserPN = dyn_cast<PHINode>(User)) 20188a8624f8e104e1ba1ca21efa6ae23680b528a3eChris Lattner V = GetValueAtEndOfBlock(UserPN->getIncomingBlock(U)); 20288a8624f8e104e1ba1ca21efa6ae23680b528a3eChris Lattner else 20388a8624f8e104e1ba1ca21efa6ae23680b528a3eChris Lattner V = GetValueInMiddleOfBlock(User->getParent()); 204ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 205f993327e71d826dcb852929a78881569ef83374dTorok Edwin U.set(V); 20693f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner} 20793f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner 208ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner/// RewriteUseAfterInsertions - Rewrite a use, just like RewriteUse. However, 209ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner/// this version of the method can rewrite uses in the same block as a 210ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner/// definition, because it assumes that all uses of a value are below any 211ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner/// inserted values. 212ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattnervoid SSAUpdater::RewriteUseAfterInsertions(Use &U) { 213ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner Instruction *User = cast<Instruction>(U.getUser()); 214ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner 215ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner Value *V; 216ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner if (PHINode *UserPN = dyn_cast<PHINode>(User)) 217ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner V = GetValueAtEndOfBlock(UserPN->getIncomingBlock(U)); 218ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner else 219ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner V = GetValueAtEndOfBlock(User->getParent()); 220ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner 221ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner U.set(V); 222ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner} 223ffd9beefb8d1fc854fc2863ad443a557be2b4196Chris Lattner 2244aad88d1fd88413029dd05255306b07cb19396eeBob Wilson/// PHIiter - Iterator for PHI operands. This is used for the PHI_iterator 2254aad88d1fd88413029dd05255306b07cb19396eeBob Wilson/// in the SSAUpdaterImpl template. 2264aad88d1fd88413029dd05255306b07cb19396eeBob Wilsonnamespace { 2274aad88d1fd88413029dd05255306b07cb19396eeBob Wilson class PHIiter { 2284aad88d1fd88413029dd05255306b07cb19396eeBob Wilson private: 2294aad88d1fd88413029dd05255306b07cb19396eeBob Wilson PHINode *PHI; 2304aad88d1fd88413029dd05255306b07cb19396eeBob Wilson unsigned idx; 2314aad88d1fd88413029dd05255306b07cb19396eeBob Wilson 2324aad88d1fd88413029dd05255306b07cb19396eeBob Wilson public: 2334aad88d1fd88413029dd05255306b07cb19396eeBob Wilson explicit PHIiter(PHINode *P) // begin iterator 2344aad88d1fd88413029dd05255306b07cb19396eeBob Wilson : PHI(P), idx(0) {} 2354aad88d1fd88413029dd05255306b07cb19396eeBob Wilson PHIiter(PHINode *P, bool) // end iterator 2364aad88d1fd88413029dd05255306b07cb19396eeBob Wilson : PHI(P), idx(PHI->getNumIncomingValues()) {} 2374aad88d1fd88413029dd05255306b07cb19396eeBob Wilson 2384aad88d1fd88413029dd05255306b07cb19396eeBob Wilson PHIiter &operator++() { ++idx; return *this; } 2394aad88d1fd88413029dd05255306b07cb19396eeBob Wilson bool operator==(const PHIiter& x) const { return idx == x.idx; } 2404aad88d1fd88413029dd05255306b07cb19396eeBob Wilson bool operator!=(const PHIiter& x) const { return !operator==(x); } 2414aad88d1fd88413029dd05255306b07cb19396eeBob Wilson Value *getIncomingValue() { return PHI->getIncomingValue(idx); } 2424aad88d1fd88413029dd05255306b07cb19396eeBob Wilson BasicBlock *getIncomingBlock() { return PHI->getIncomingBlock(idx); } 2434aad88d1fd88413029dd05255306b07cb19396eeBob Wilson }; 24484bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson} 24584bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson 2464aad88d1fd88413029dd05255306b07cb19396eeBob Wilson/// SSAUpdaterTraits<SSAUpdater> - Traits for the SSAUpdaterImpl template, 2474aad88d1fd88413029dd05255306b07cb19396eeBob Wilson/// specialized for SSAUpdater. 2484aad88d1fd88413029dd05255306b07cb19396eeBob Wilsonnamespace llvm { 2494aad88d1fd88413029dd05255306b07cb19396eeBob Wilsontemplate<> 2504aad88d1fd88413029dd05255306b07cb19396eeBob Wilsonclass SSAUpdaterTraits<SSAUpdater> { 2514aad88d1fd88413029dd05255306b07cb19396eeBob Wilsonpublic: 2524aad88d1fd88413029dd05255306b07cb19396eeBob Wilson typedef BasicBlock BlkT; 2534aad88d1fd88413029dd05255306b07cb19396eeBob Wilson typedef Value *ValT; 2544aad88d1fd88413029dd05255306b07cb19396eeBob Wilson typedef PHINode PhiT; 2554aad88d1fd88413029dd05255306b07cb19396eeBob Wilson 2564aad88d1fd88413029dd05255306b07cb19396eeBob Wilson typedef succ_iterator BlkSucc_iterator; 2574aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static BlkSucc_iterator BlkSucc_begin(BlkT *BB) { return succ_begin(BB); } 2584aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static BlkSucc_iterator BlkSucc_end(BlkT *BB) { return succ_end(BB); } 2594aad88d1fd88413029dd05255306b07cb19396eeBob Wilson 2604aad88d1fd88413029dd05255306b07cb19396eeBob Wilson typedef PHIiter PHI_iterator; 2614aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static inline PHI_iterator PHI_begin(PhiT *PHI) { return PHI_iterator(PHI); } 2624aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static inline PHI_iterator PHI_end(PhiT *PHI) { 2634aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return PHI_iterator(PHI, true); 26484bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 26549c283fd3f8f81e04b84dc848981b4bf17b2d706Bob Wilson 2664aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// FindPredecessorBlocks - Put the predecessors of Info->BB into the Preds 2674aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// vector, set Info->NumPreds, and allocate space in Info->Preds. 2684aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static void FindPredecessorBlocks(BasicBlock *BB, 2694aad88d1fd88413029dd05255306b07cb19396eeBob Wilson SmallVectorImpl<BasicBlock*> *Preds) { 2704aad88d1fd88413029dd05255306b07cb19396eeBob Wilson // We can get our predecessor info by walking the pred_iterator list, 2714aad88d1fd88413029dd05255306b07cb19396eeBob Wilson // but it is relatively slow. If we already have PHI nodes in this 2724aad88d1fd88413029dd05255306b07cb19396eeBob Wilson // block, walk one of them to get the predecessor list instead. 2734aad88d1fd88413029dd05255306b07cb19396eeBob Wilson if (PHINode *SomePhi = dyn_cast<PHINode>(BB->begin())) { 2744aad88d1fd88413029dd05255306b07cb19396eeBob Wilson for (unsigned PI = 0, E = SomePhi->getNumIncomingValues(); PI != E; ++PI) 2754aad88d1fd88413029dd05255306b07cb19396eeBob Wilson Preds->push_back(SomePhi->getIncomingBlock(PI)); 2764aad88d1fd88413029dd05255306b07cb19396eeBob Wilson } else { 2774aad88d1fd88413029dd05255306b07cb19396eeBob Wilson for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 2784aad88d1fd88413029dd05255306b07cb19396eeBob Wilson Preds->push_back(*PI); 27984bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 28084bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 28184bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson 2824aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// GetUndefVal - Get an undefined value of the same type as the value 2834aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// being handled. 2844aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static Value *GetUndefVal(BasicBlock *BB, SSAUpdater *Updater) { 285fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands return UndefValue::get(Updater->ProtoType); 28684bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 28784bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson 2884aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// CreateEmptyPHI - Create a new PHI instruction in the specified block. 2894aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// Reserve space for the operands but do not fill them in yet. 2904aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static Value *CreateEmptyPHI(BasicBlock *BB, unsigned NumPreds, 2914aad88d1fd88413029dd05255306b07cb19396eeBob Wilson SSAUpdater *Updater) { 292fc6e29d4ab52b7d3efd83846ed495a9ca7e51e49Duncan Sands PHINode *PHI = PHINode::Create(Updater->ProtoType, Updater->ProtoName, 2934aad88d1fd88413029dd05255306b07cb19396eeBob Wilson &BB->front()); 2944aad88d1fd88413029dd05255306b07cb19396eeBob Wilson PHI->reserveOperandSpace(NumPreds); 2954aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return PHI; 296a0c6057061be055faa542d05b2213f2bd779e160Bob Wilson } 297a0c6057061be055faa542d05b2213f2bd779e160Bob Wilson 2984aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// AddPHIOperand - Add the specified value as an operand of the PHI for 2994aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// the specified predecessor block. 3004aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static void AddPHIOperand(PHINode *PHI, Value *Val, BasicBlock *Pred) { 3014aad88d1fd88413029dd05255306b07cb19396eeBob Wilson PHI->addIncoming(Val, Pred); 30284bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 303ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 3044aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// InstrIsPHI - Check if an instruction is a PHI. 3054aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// 3064aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static PHINode *InstrIsPHI(Instruction *I) { 3074aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return dyn_cast<PHINode>(I); 308a0c6057061be055faa542d05b2213f2bd779e160Bob Wilson } 30945305d4ff6bff8dfe62228c68b3cb61bb2d7254fChris Lattner 3104aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// ValueIsPHI - Check if a value is a PHI. 3114aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// 3124aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static PHINode *ValueIsPHI(Value *Val, SSAUpdater *Updater) { 3134aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return dyn_cast<PHINode>(Val); 31484bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 315ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 3164aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// ValueIsNewPHI - Like ValueIsPHI but also check if the PHI has no source 3174aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// operands, i.e., it was just added. 3184aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static PHINode *ValueIsNewPHI(Value *Val, SSAUpdater *Updater) { 3194aad88d1fd88413029dd05255306b07cb19396eeBob Wilson PHINode *PHI = ValueIsPHI(Val, Updater); 3204aad88d1fd88413029dd05255306b07cb19396eeBob Wilson if (PHI && PHI->getNumIncomingValues() == 0) 3214aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return PHI; 3224aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return 0; 32384bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 32484bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson 3254aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// GetPHIValue - For the specified PHI instruction, return the value 3264aad88d1fd88413029dd05255306b07cb19396eeBob Wilson /// that it defines. 3274aad88d1fd88413029dd05255306b07cb19396eeBob Wilson static Value *GetPHIValue(PHINode *PHI) { 3284aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return PHI; 32984bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson } 3304aad88d1fd88413029dd05255306b07cb19396eeBob Wilson}; 33184bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson 3324aad88d1fd88413029dd05255306b07cb19396eeBob Wilson} // End llvm namespace 333ed90342d8ae0756305219e0f01e03e77599ebb41Duncan Sands 3344aad88d1fd88413029dd05255306b07cb19396eeBob Wilson/// GetValueAtEndOfBlockInternal - Check to see if AvailableVals has an entry 3354aad88d1fd88413029dd05255306b07cb19396eeBob Wilson/// for the specified BB and if so, return it. If not, construct SSA form by 3364aad88d1fd88413029dd05255306b07cb19396eeBob Wilson/// first calculating the required placement of PHIs and then inserting new 3374aad88d1fd88413029dd05255306b07cb19396eeBob Wilson/// PHIs where needed. 3384aad88d1fd88413029dd05255306b07cb19396eeBob WilsonValue *SSAUpdater::GetValueAtEndOfBlockInternal(BasicBlock *BB) { 33984bd6b0c31f41cdd1d859dab54b6bc1177c4c6bbBob Wilson AvailableValsTy &AvailableVals = getAvailableVals(AV); 3404aad88d1fd88413029dd05255306b07cb19396eeBob Wilson if (Value *V = AvailableVals[BB]) 3414aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return V; 3424aad88d1fd88413029dd05255306b07cb19396eeBob Wilson 3434aad88d1fd88413029dd05255306b07cb19396eeBob Wilson SSAUpdaterImpl<SSAUpdater> Impl(this, &AvailableVals, InsertedPHIs); 3444aad88d1fd88413029dd05255306b07cb19396eeBob Wilson return Impl.GetValue(BB); 34593f3bcf7f323069e40d9abb950da73d437b6f7daChris Lattner} 346a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 347a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner//===----------------------------------------------------------------------===// 348a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner// LoadAndStorePromoter Implementation 349a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner//===----------------------------------------------------------------------===// 350a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 351deaf55f69865bbc997a569c2a689ec5b0fbdefefChris LattnerLoadAndStorePromoter:: 352deaf55f69865bbc997a569c2a689ec5b0fbdefefChris LattnerLoadAndStorePromoter(const SmallVectorImpl<Instruction*> &Insts, 353deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner SSAUpdater &S, StringRef BaseName) : SSA(S) { 354a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (Insts.empty()) return; 355a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 356deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner Value *SomeVal; 357a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(Insts[0])) 358deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner SomeVal = LI; 359a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner else 360deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner SomeVal = cast<StoreInst>(Insts[0])->getOperand(0); 361deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner 362deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner if (BaseName.empty()) 363deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner BaseName = SomeVal->getName(); 364deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner SSA.Initialize(SomeVal->getType(), BaseName); 365deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner} 366deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner 367deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner 368deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattnervoid LoadAndStorePromoter:: 369deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattnerrun(const SmallVectorImpl<Instruction*> &Insts) const { 370a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 371a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // First step: bucket up uses of the alloca by the block they occur in. 372a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // This is important because we have to handle multiple defs/uses in a block 373a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // ourselves: SSAUpdater is purely for cross-block references. 374a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // FIXME: Want a TinyVector<Instruction*> since there is often 0/1 element. 375a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner DenseMap<BasicBlock*, std::vector<Instruction*> > UsesByBlock; 376a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 377a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner for (unsigned i = 0, e = Insts.size(); i != e; ++i) { 378a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner Instruction *User = Insts[i]; 379a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner UsesByBlock[User->getParent()].push_back(User); 380a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 381a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 382a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Okay, now we can iterate over all the blocks in the function with uses, 383a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // processing them. Keep track of which loads are loading a live-in value. 384a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Walk the uses in the use-list order to be determinstic. 385a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner SmallVector<LoadInst*, 32> LiveInLoads; 386a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner DenseMap<Value*, Value*> ReplacedLoads; 387a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 388a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner for (unsigned i = 0, e = Insts.size(); i != e; ++i) { 389a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner Instruction *User = Insts[i]; 390a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner BasicBlock *BB = User->getParent(); 391a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner std::vector<Instruction*> &BlockUses = UsesByBlock[BB]; 392a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 393a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // If this block has already been processed, ignore this repeat use. 394a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (BlockUses.empty()) continue; 395a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 396a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Okay, this is the first use in the block. If this block just has a 397a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // single user in it, we can rewrite it trivially. 398a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (BlockUses.size() == 1) { 399a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // If it is a store, it is a trivial def of the value in the block. 400a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (StoreInst *SI = dyn_cast<StoreInst>(User)) 401deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner SSA.AddAvailableValue(BB, SI->getOperand(0)); 402a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner else 403a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Otherwise it is a load, queue it to rewrite as a live-in load. 404a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner LiveInLoads.push_back(cast<LoadInst>(User)); 405a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner BlockUses.clear(); 406a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner continue; 407a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 408a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 409a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Otherwise, check to see if this block is all loads. 410a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner bool HasStore = false; 411a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner for (unsigned i = 0, e = BlockUses.size(); i != e; ++i) { 412a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (isa<StoreInst>(BlockUses[i])) { 413a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner HasStore = true; 414a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner break; 415a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 416a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 417a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 418a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // If so, we can queue them all as live in loads. We don't have an 419a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // efficient way to tell which on is first in the block and don't want to 420a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // scan large blocks, so just add all loads as live ins. 421a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (!HasStore) { 422a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner for (unsigned i = 0, e = BlockUses.size(); i != e; ++i) 423a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner LiveInLoads.push_back(cast<LoadInst>(BlockUses[i])); 424a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner BlockUses.clear(); 425a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner continue; 426a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 427a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 428a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Otherwise, we have mixed loads and stores (or just a bunch of stores). 429a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Since SSAUpdater is purely for cross-block values, we need to determine 430a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // the order of these instructions in the block. If the first use in the 431a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // block is a load, then it uses the live in value. The last store defines 432a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // the live out value. We handle this by doing a linear scan of the block. 433a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner Value *StoredValue = 0; 434a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { 435a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (LoadInst *L = dyn_cast<LoadInst>(II)) { 436a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // If this is a load from an unrelated pointer, ignore it. 437a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (!isInstInList(L, Insts)) continue; 438a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 439a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // If we haven't seen a store yet, this is a live in use, otherwise 440a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // use the stored value. 441a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (StoredValue) { 442deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner replaceLoadWithValue(L, StoredValue); 443a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner L->replaceAllUsesWith(StoredValue); 444a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner ReplacedLoads[L] = StoredValue; 445a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } else { 446a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner LiveInLoads.push_back(L); 447a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 448a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner continue; 449a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 450a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 451a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (StoreInst *S = dyn_cast<StoreInst>(II)) { 452a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // If this is a store to an unrelated pointer, ignore it. 453a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (!isInstInList(S, Insts)) continue; 454a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 455a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Remember that this is the active value in the block. 456a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner StoredValue = S->getOperand(0); 457a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 458a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 459a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 460a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // The last stored value that happened is the live-out for the block. 461a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner assert(StoredValue && "Already checked that there is a store in block"); 462deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner SSA.AddAvailableValue(BB, StoredValue); 463a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner BlockUses.clear(); 464a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 465a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 466a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Okay, now we rewrite all loads that use live-in values in the loop, 467a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // inserting PHI nodes as necessary. 468a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner for (unsigned i = 0, e = LiveInLoads.size(); i != e; ++i) { 469a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner LoadInst *ALoad = LiveInLoads[i]; 470deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner Value *NewVal = SSA.GetValueInMiddleOfBlock(ALoad->getParent()); 471deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner replaceLoadWithValue(ALoad, NewVal); 472867be59684afef29f058385c6618ec7753596ffcChris Lattner 473867be59684afef29f058385c6618ec7753596ffcChris Lattner // Avoid assertions in unreachable code. 474867be59684afef29f058385c6618ec7753596ffcChris Lattner if (NewVal == ALoad) NewVal = UndefValue::get(NewVal->getType()); 475a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner ALoad->replaceAllUsesWith(NewVal); 476a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner ReplacedLoads[ALoad] = NewVal; 477a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 478a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 479deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner // Allow the client to do stuff before we start nuking things. 480deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner doExtraRewritesBeforeFinalDeletion(); 481deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner 482a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Now that everything is rewritten, delete the old instructions from the 483a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // function. They should all be dead now. 484a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner for (unsigned i = 0, e = Insts.size(); i != e; ++i) { 485a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner Instruction *User = Insts[i]; 486a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 487a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // If this is a load that still has uses, then the load must have been added 488a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // as a live value in the SSAUpdate data structure for a block (e.g. because 489a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // the loaded value was stored later). In this case, we need to recursively 490a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // propagate the updates until we get to the real value. 491a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner if (!User->use_empty()) { 492a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner Value *NewVal = ReplacedLoads[User]; 493a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner assert(NewVal && "not a replaced load?"); 494a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 495a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // Propagate down to the ultimate replacee. The intermediately loads 496a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // could theoretically already have been deleted, so we don't want to 497a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner // dereference the Value*'s. 498a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner DenseMap<Value*, Value*>::iterator RLI = ReplacedLoads.find(NewVal); 499a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner while (RLI != ReplacedLoads.end()) { 500a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner NewVal = RLI->second; 501a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner RLI = ReplacedLoads.find(NewVal); 502a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 503a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 504deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner replaceLoadWithValue(cast<LoadInst>(User), NewVal); 505a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner User->replaceAllUsesWith(NewVal); 506a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 507a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner 508deaf55f69865bbc997a569c2a689ec5b0fbdefefChris Lattner instructionDeleted(User); 509a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner User->eraseFromParent(); 510a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner } 511a2d845a3ff0b11ca7de6dd0485aa23edef7d149aChris Lattner} 512