Chris Lattner | 184b298 | 2002-09-08 18:59:35 +0000 | [diff] [blame] | 1 | //===-- BasicBlock.cpp - Implement BasicBlock related methods -------------===// |
John Criswell | 482202a | 2003-10-20 19:43:21 +0000 | [diff] [blame] | 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file was developed by the LLVM research group and is distributed under |
| 6 | // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 9 | // |
Chris Lattner | f739fa8 | 2002-04-08 22:03:57 +0000 | [diff] [blame] | 10 | // This file implements the BasicBlock class for the VMCore library. |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 14 | #include "llvm/BasicBlock.h" |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 15 | #include "llvm/iTerminators.h" |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 16 | #include "llvm/Type.h" |
Chris Lattner | 83d485b | 2002-02-12 22:39:50 +0000 | [diff] [blame] | 17 | #include "llvm/Support/CFG.h" |
Chris Lattner | 5cd012d | 2002-05-23 16:52:34 +0000 | [diff] [blame] | 18 | #include "llvm/Constant.h" |
Chris Lattner | fb5ae02 | 2001-12-03 18:02:31 +0000 | [diff] [blame] | 19 | #include "llvm/iPHINode.h" |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 20 | #include "llvm/SymbolTable.h" |
Chris Lattner | 184b298 | 2002-09-08 18:59:35 +0000 | [diff] [blame] | 21 | #include "Support/LeakDetector.h" |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 22 | #include "SymbolTableListTraitsImpl.h" |
| 23 | #include <algorithm> |
Chris Lattner | a296000 | 2003-11-21 16:52:05 +0000 | [diff] [blame] | 24 | using namespace llvm; |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 25 | |
Chris Lattner | a296000 | 2003-11-21 16:52:05 +0000 | [diff] [blame] | 26 | namespace { |
| 27 | /// DummyInst - An instance of this class is used to mark the end of the |
| 28 | /// instruction list. This is not a real instruction. |
| 29 | struct DummyInst : public Instruction { |
| 30 | DummyInst() : Instruction(Type::VoidTy, OtherOpsEnd) { |
| 31 | // This should not be garbage monitored. |
| 32 | LeakDetector::removeGarbageObject(this); |
| 33 | } |
Brian Gaeke | 960707c | 2003-11-11 22:41:34 +0000 | [diff] [blame] | 34 | |
Chris Lattner | a296000 | 2003-11-21 16:52:05 +0000 | [diff] [blame] | 35 | virtual Instruction *clone() const { |
| 36 | assert(0 && "Cannot clone EOL");abort(); |
| 37 | return 0; |
| 38 | } |
| 39 | virtual const char *getOpcodeName() const { return "*end-of-list-inst*"; } |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 40 | |
Chris Lattner | a296000 | 2003-11-21 16:52:05 +0000 | [diff] [blame] | 41 | // Methods for support type inquiry through isa, cast, and dyn_cast... |
| 42 | static inline bool classof(const DummyInst *) { return true; } |
| 43 | static inline bool classof(const Instruction *I) { |
| 44 | return I->getOpcode() == OtherOpsEnd; |
| 45 | } |
| 46 | static inline bool classof(const Value *V) { |
| 47 | return isa<Instruction>(V) && classof(cast<Instruction>(V)); |
| 48 | } |
| 49 | }; |
| 50 | } |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 51 | |
| 52 | Instruction *ilist_traits<Instruction>::createNode() { |
| 53 | return new DummyInst(); |
| 54 | } |
| 55 | iplist<Instruction> &ilist_traits<Instruction>::getList(BasicBlock *BB) { |
| 56 | return BB->getInstList(); |
| 57 | } |
| 58 | |
| 59 | // Explicit instantiation of SymbolTableListTraits since some of the methods |
| 60 | // are not in the public header file... |
Chris Lattner | 41baa98 | 2003-11-05 05:15:42 +0000 | [diff] [blame] | 61 | template class SymbolTableListTraits<Instruction, BasicBlock, Function>; |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 62 | |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 63 | |
Chris Lattner | bb5f0db | 2004-02-04 03:57:50 +0000 | [diff] [blame] | 64 | BasicBlock::BasicBlock(const std::string &Name, Function *Parent, |
| 65 | BasicBlock *InsertBefore) |
Chris Lattner | 4dfede8 | 2002-09-26 05:03:22 +0000 | [diff] [blame] | 66 | : Value(Type::LabelTy, Value::BasicBlockVal, Name) { |
| 67 | // Initialize the instlist... |
| 68 | InstList.setItemParent(this); |
| 69 | |
| 70 | // Make sure that we get added to a function |
| 71 | LeakDetector::addGarbageObject(this); |
| 72 | |
| 73 | if (InsertBefore) { |
Chris Lattner | bb5f0db | 2004-02-04 03:57:50 +0000 | [diff] [blame] | 74 | assert(Parent && |
| 75 | "Cannot insert block before another block with no function!"); |
| 76 | Parent->getBasicBlockList().insert(InsertBefore, this); |
| 77 | } else if (Parent) { |
| 78 | Parent->getBasicBlockList().push_back(this); |
Chris Lattner | 4dfede8 | 2002-09-26 05:03:22 +0000 | [diff] [blame] | 79 | } |
| 80 | } |
| 81 | |
| 82 | |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 83 | BasicBlock::~BasicBlock() { |
Misha Brukman | ede10c9 | 2004-04-16 17:37:12 +0000 | [diff] [blame] | 84 | assert(getParent() == 0 && "BasicBlock still linked into the program!"); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 85 | dropAllReferences(); |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 86 | InstList.clear(); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 87 | } |
| 88 | |
Chris Lattner | 9ed7aef | 2002-09-06 21:33:15 +0000 | [diff] [blame] | 89 | void BasicBlock::setParent(Function *parent) { |
Chris Lattner | 184b298 | 2002-09-08 18:59:35 +0000 | [diff] [blame] | 90 | if (getParent()) |
| 91 | LeakDetector::addGarbageObject(this); |
| 92 | |
Chris Lattner | 9ed7aef | 2002-09-06 21:33:15 +0000 | [diff] [blame] | 93 | InstList.setParent(parent); |
Chris Lattner | 184b298 | 2002-09-08 18:59:35 +0000 | [diff] [blame] | 94 | |
| 95 | if (getParent()) |
| 96 | LeakDetector::removeGarbageObject(this); |
Chris Lattner | 9ed7aef | 2002-09-06 21:33:15 +0000 | [diff] [blame] | 97 | } |
| 98 | |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 99 | // Specialize setName to take care of symbol table majik |
Chris Lattner | 7f74a56 | 2002-01-20 22:54:45 +0000 | [diff] [blame] | 100 | void BasicBlock::setName(const std::string &name, SymbolTable *ST) { |
Chris Lattner | f739fa8 | 2002-04-08 22:03:57 +0000 | [diff] [blame] | 101 | Function *P; |
Chris Lattner | 98cf1f5 | 2002-11-20 18:36:02 +0000 | [diff] [blame] | 102 | assert((ST == 0 || (!getParent() || ST == &getParent()->getSymbolTable())) && |
Chris Lattner | 2d189a5 | 2001-09-07 16:44:17 +0000 | [diff] [blame] | 103 | "Invalid symtab argument!"); |
Chris Lattner | 98cf1f5 | 2002-11-20 18:36:02 +0000 | [diff] [blame] | 104 | if ((P = getParent()) && hasName()) P->getSymbolTable().remove(this); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 105 | Value::setName(name); |
Chris Lattner | 98cf1f5 | 2002-11-20 18:36:02 +0000 | [diff] [blame] | 106 | if (P && hasName()) P->getSymbolTable().insert(this); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 107 | } |
| 108 | |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 109 | TerminatorInst *BasicBlock::getTerminator() { |
| 110 | if (InstList.empty()) return 0; |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 111 | return dyn_cast<TerminatorInst>(&InstList.back()); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 112 | } |
| 113 | |
| 114 | const TerminatorInst *const BasicBlock::getTerminator() const { |
| 115 | if (InstList.empty()) return 0; |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 116 | return dyn_cast<TerminatorInst>(&InstList.back()); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 117 | } |
| 118 | |
| 119 | void BasicBlock::dropAllReferences() { |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 120 | for(iterator I = begin(), E = end(); I != E; ++I) |
| 121 | I->dropAllReferences(); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 122 | } |
| 123 | |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 124 | // removePredecessor - This method is used to notify a BasicBlock that the |
| 125 | // specified Predecessor of the block is no longer able to reach it. This is |
| 126 | // actually not used to update the Predecessor list, but is actually used to |
| 127 | // update the PHI nodes that reside in the block. Note that this should be |
| 128 | // called while the predecessor still refers to this block. |
| 129 | // |
| 130 | void BasicBlock::removePredecessor(BasicBlock *Pred) { |
Chris Lattner | 83d485b | 2002-02-12 22:39:50 +0000 | [diff] [blame] | 131 | assert(find(pred_begin(this), pred_end(this), Pred) != pred_end(this) && |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 132 | "removePredecessor: BB is not a predecessor!"); |
Chris Lattner | da55810 | 2001-10-02 03:41:24 +0000 | [diff] [blame] | 133 | if (!isa<PHINode>(front())) return; // Quick exit. |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 134 | |
Chris Lattner | 83d485b | 2002-02-12 22:39:50 +0000 | [diff] [blame] | 135 | pred_iterator PI(pred_begin(this)), EI(pred_end(this)); |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 136 | unsigned max_idx; |
| 137 | |
| 138 | // Loop over the rest of the predecessors until we run out, or until we find |
| 139 | // out that there are more than 2 predecessors. |
| 140 | for (max_idx = 0; PI != EI && max_idx < 3; ++PI, ++max_idx) /*empty*/; |
| 141 | |
| 142 | // If there are exactly two predecessors, then we want to nuke the PHI nodes |
Chris Lattner | f7373e4 | 2002-05-21 19:52:49 +0000 | [diff] [blame] | 143 | // altogether. We cannot do this, however if this in this case however: |
| 144 | // |
| 145 | // Loop: |
| 146 | // %x = phi [X, Loop] |
| 147 | // %x2 = add %x, 1 ;; This would become %x2 = add %x2, 1 |
| 148 | // br Loop ;; %x2 does not dominate all uses |
| 149 | // |
| 150 | // This is because the PHI node input is actually taken from the predecessor |
| 151 | // basic block. The only case this can happen is with a self loop, so we |
| 152 | // check for this case explicitly now. |
| 153 | // |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 154 | assert(max_idx != 0 && "PHI Node in block with 0 predecessors!?!?!"); |
Chris Lattner | f7373e4 | 2002-05-21 19:52:49 +0000 | [diff] [blame] | 155 | if (max_idx == 2) { |
| 156 | PI = pred_begin(this); |
| 157 | BasicBlock *Other = *PI == Pred ? *++PI : *PI; |
| 158 | |
| 159 | // Disable PHI elimination! |
| 160 | if (this == Other) max_idx = 3; |
| 161 | } |
| 162 | |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 163 | if (max_idx <= 2) { // <= Two predecessors BEFORE I remove one? |
Chris Lattner | da55810 | 2001-10-02 03:41:24 +0000 | [diff] [blame] | 164 | // Yup, loop through and nuke the PHI nodes |
Chris Lattner | 113f4f4 | 2002-06-25 16:13:24 +0000 | [diff] [blame] | 165 | while (PHINode *PN = dyn_cast<PHINode>(&front())) { |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 166 | PN->removeIncomingValue(Pred); // Remove the predecessor first... |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 167 | |
| 168 | // If the PHI _HAD_ two uses, replace PHI node with its now *single* value |
Chris Lattner | caf5b50 | 2002-10-08 21:36:34 +0000 | [diff] [blame] | 169 | if (max_idx == 2) { |
Chris Lattner | ef8c833 | 2003-04-25 23:14:19 +0000 | [diff] [blame] | 170 | if (PN->getOperand(0) != PN) |
| 171 | PN->replaceAllUsesWith(PN->getOperand(0)); |
| 172 | else |
| 173 | // We are left with an infinite loop with no entries: kill the PHI. |
| 174 | PN->replaceAllUsesWith(Constant::getNullValue(PN->getType())); |
Chris Lattner | caf5b50 | 2002-10-08 21:36:34 +0000 | [diff] [blame] | 175 | getInstList().pop_front(); // Remove the PHI node |
| 176 | } |
| 177 | |
| 178 | // If the PHI node already only had one entry, it got deleted by |
| 179 | // removeIncomingValue. |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 180 | } |
| 181 | } else { |
| 182 | // Okay, now we know that we need to remove predecessor #pred_idx from all |
| 183 | // PHI nodes. Iterate over each PHI node fixing them up |
Chris Lattner | 708ee9d | 2004-06-05 00:11:27 +0000 | [diff] [blame^] | 184 | PHINode *PN; |
| 185 | for (iterator II = begin(); PN = dyn_cast<PHINode>(II); ++II) |
Chris Lattner | f7373e4 | 2002-05-21 19:52:49 +0000 | [diff] [blame] | 186 | PN->removeIncomingValue(Pred); |
Chris Lattner | 615d3cf | 2001-06-29 05:25:23 +0000 | [diff] [blame] | 187 | } |
| 188 | } |
| 189 | |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 190 | |
| 191 | // splitBasicBlock - This splits a basic block into two at the specified |
| 192 | // instruction. Note that all instructions BEFORE the specified iterator stay |
| 193 | // as part of the original basic block, an unconditional branch is added to |
| 194 | // the new BB, and the rest of the instructions in the BB are moved to the new |
| 195 | // BB, including the old terminator. This invalidates the iterator. |
| 196 | // |
| 197 | // Note that this only works on well formed basic blocks (must have a |
| 198 | // terminator), and 'I' must not be the end of instruction list (which would |
| 199 | // cause a degenerate basic block to be formed, having a terminator inside of |
| 200 | // the basic block). |
| 201 | // |
Chris Lattner | 6d56935 | 2003-08-24 03:41:39 +0000 | [diff] [blame] | 202 | BasicBlock *BasicBlock::splitBasicBlock(iterator I, const std::string &BBName) { |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 203 | assert(getTerminator() && "Can't use splitBasicBlock on degenerate BB!"); |
| 204 | assert(I != InstList.end() && |
| 205 | "Trying to get me to create degenerate basic block!"); |
| 206 | |
Chris Lattner | bb5f0db | 2004-02-04 03:57:50 +0000 | [diff] [blame] | 207 | BasicBlock *New = new BasicBlock(BBName, getParent(), getNext()); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 208 | |
Chris Lattner | c4c7ea5 | 2004-02-03 23:11:21 +0000 | [diff] [blame] | 209 | // Move all of the specified instructions from the original basic block into |
| 210 | // the new basic block. |
| 211 | New->getInstList().splice(New->end(), this->getInstList(), I, end()); |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 212 | |
| 213 | // Add a branch instruction to the newly formed basic block. |
Chris Lattner | a296000 | 2003-11-21 16:52:05 +0000 | [diff] [blame] | 214 | new BranchInst(New, this); |
Chris Lattner | 4eed0b8 | 2002-02-25 00:35:07 +0000 | [diff] [blame] | 215 | |
| 216 | // Now we must loop through all of the successors of the New block (which |
| 217 | // _were_ the successors of the 'this' block), and update any PHI nodes in |
| 218 | // successors. If there were PHI nodes in the successors, then they need to |
| 219 | // know that incoming branches will be from New, not from Old. |
| 220 | // |
Chris Lattner | 64d88bc | 2003-09-24 22:03:22 +0000 | [diff] [blame] | 221 | for (succ_iterator I = succ_begin(New), E = succ_end(New); I != E; ++I) { |
Chris Lattner | 4eed0b8 | 2002-02-25 00:35:07 +0000 | [diff] [blame] | 222 | // Loop over any phi nodes in the basic block, updating the BB field of |
| 223 | // incoming values... |
| 224 | BasicBlock *Successor = *I; |
Chris Lattner | 708ee9d | 2004-06-05 00:11:27 +0000 | [diff] [blame^] | 225 | PHINode *PN; |
Chris Lattner | 4eed0b8 | 2002-02-25 00:35:07 +0000 | [diff] [blame] | 226 | for (BasicBlock::iterator II = Successor->begin(); |
Chris Lattner | 708ee9d | 2004-06-05 00:11:27 +0000 | [diff] [blame^] | 227 | PN = dyn_cast<PHINode>(II); ++II) { |
Chris Lattner | 4eed0b8 | 2002-02-25 00:35:07 +0000 | [diff] [blame] | 228 | int IDX = PN->getBasicBlockIndex(this); |
| 229 | while (IDX != -1) { |
| 230 | PN->setIncomingBlock((unsigned)IDX, New); |
| 231 | IDX = PN->getBasicBlockIndex(this); |
| 232 | } |
| 233 | } |
| 234 | } |
Chris Lattner | 2f7c963 | 2001-06-06 20:29:01 +0000 | [diff] [blame] | 235 | return New; |
| 236 | } |