BasicBlock.cpp revision ad993cbb77b26b36cee938686b3377c0d92abd5e
1d1e693f2a3883dacf213aa2b477540c57b53b714Chris Lattner//===-- BasicBlock.cpp - Implement BasicBlock related methods -------------===// 2b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 5b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// This file was developed by the LLVM research group and is distributed under 6b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// the University of Illinois Open Source License. See LICENSE.TXT for details. 7b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 9009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// 10b7653df0853f06112b741be09f1b7ae5a6aa6fdeChris Lattner// This file implements the BasicBlock class for the VMCore library. 11009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// 12009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner//===----------------------------------------------------------------------===// 13009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 147e70829632f82de15db187845666aaca6e04b792Chris Lattner#include "llvm/BasicBlock.h" 1544336292fcd9f3f99cbfc2c3366bea0cf95bb675Misha Brukman#include "llvm/Constant.h" 1644336292fcd9f3f99cbfc2c3366bea0cf95bb675Misha Brukman#include "llvm/Instructions.h" 17009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner#include "llvm/Type.h" 18455889aa79e3463a4b0f2161e3d9d72a683268b6Chris Lattner#include "llvm/Support/CFG.h" 197e70829632f82de15db187845666aaca6e04b792Chris Lattner#include "llvm/SymbolTable.h" 20551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/Support/LeakDetector.h" 217e70829632f82de15db187845666aaca6e04b792Chris Lattner#include "SymbolTableListTraitsImpl.h" 227e70829632f82de15db187845666aaca6e04b792Chris Lattner#include <algorithm> 23108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattnerusing namespace llvm; 24108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner 25108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattnernamespace { 26108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner /// DummyInst - An instance of this class is used to mark the end of the 27108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner /// instruction list. This is not a real instruction. 28108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner struct DummyInst : public Instruction { 2996d83f63cdbb33c075901b1b84eb07622d86386fChris Lattner DummyInst() : Instruction(Type::VoidTy, OtherOpsEnd, 0, 0) { 30108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner // This should not be garbage monitored. 31108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner LeakDetector::removeGarbageObject(this); 32108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner } 33009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 34108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner virtual Instruction *clone() const { 35108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner assert(0 && "Cannot clone EOL");abort(); 36108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner return 0; 37108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner } 38108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner virtual const char *getOpcodeName() const { return "*end-of-list-inst*"; } 397e70829632f82de15db187845666aaca6e04b792Chris Lattner 40108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner // Methods for support type inquiry through isa, cast, and dyn_cast... 41108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner static inline bool classof(const DummyInst *) { return true; } 42108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner static inline bool classof(const Instruction *I) { 43108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner return I->getOpcode() == OtherOpsEnd; 44108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner } 45108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner static inline bool classof(const Value *V) { 46108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner return isa<Instruction>(V) && classof(cast<Instruction>(V)); 47108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner } 48108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner }; 49108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner} 507e70829632f82de15db187845666aaca6e04b792Chris Lattner 51bca81448ac8e19c588c9a4ad16fc70732b76327cChris LattnerInstruction *ilist_traits<Instruction>::createSentinel() { 527e70829632f82de15db187845666aaca6e04b792Chris Lattner return new DummyInst(); 537e70829632f82de15db187845666aaca6e04b792Chris Lattner} 547e70829632f82de15db187845666aaca6e04b792Chris Lattneriplist<Instruction> &ilist_traits<Instruction>::getList(BasicBlock *BB) { 557e70829632f82de15db187845666aaca6e04b792Chris Lattner return BB->getInstList(); 567e70829632f82de15db187845666aaca6e04b792Chris Lattner} 577e70829632f82de15db187845666aaca6e04b792Chris Lattner 587e70829632f82de15db187845666aaca6e04b792Chris Lattner// Explicit instantiation of SymbolTableListTraits since some of the methods 597e70829632f82de15db187845666aaca6e04b792Chris Lattner// are not in the public header file... 60e860e0d69c9c155704cd3c4b2533410a8c782d9eChris Lattnertemplate class SymbolTableListTraits<Instruction, BasicBlock, Function>; 617e70829632f82de15db187845666aaca6e04b792Chris Lattner 62009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 634f05611ed948ed1fb3e861d178aae18bd025ce1cChris LattnerBasicBlock::BasicBlock(const std::string &Name, Function *Parent, 644f05611ed948ed1fb3e861d178aae18bd025ce1cChris Lattner BasicBlock *InsertBefore) 650a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner : Value(Type::LabelTy, Value::BasicBlockVal, Name) { 660a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner // Initialize the instlist... 670a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner InstList.setItemParent(this); 680a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner 690a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner // Make sure that we get added to a function 700a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner LeakDetector::addGarbageObject(this); 710a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner 720a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner if (InsertBefore) { 734f05611ed948ed1fb3e861d178aae18bd025ce1cChris Lattner assert(Parent && 744f05611ed948ed1fb3e861d178aae18bd025ce1cChris Lattner "Cannot insert block before another block with no function!"); 754f05611ed948ed1fb3e861d178aae18bd025ce1cChris Lattner Parent->getBasicBlockList().insert(InsertBefore, this); 764f05611ed948ed1fb3e861d178aae18bd025ce1cChris Lattner } else if (Parent) { 774f05611ed948ed1fb3e861d178aae18bd025ce1cChris Lattner Parent->getBasicBlockList().push_back(this); 780a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner } 790a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner} 800a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner 810a1a874d1f4659f02c0d4fdd6be69f1188bd0625Chris Lattner 82009505452b713ed2e3a8e99c5545a6e721c65495Chris LattnerBasicBlock::~BasicBlock() { 83ea51deb18a60d37e546909af4aa95ca6f2c5d56fMisha Brukman assert(getParent() == 0 && "BasicBlock still linked into the program!"); 84009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner dropAllReferences(); 857e70829632f82de15db187845666aaca6e04b792Chris Lattner InstList.clear(); 86009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner} 87009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 88bded132d00ed626a6541b67ad101ef0fd47d3491Chris Lattnervoid BasicBlock::setParent(Function *parent) { 89d1e693f2a3883dacf213aa2b477540c57b53b714Chris Lattner if (getParent()) 90d1e693f2a3883dacf213aa2b477540c57b53b714Chris Lattner LeakDetector::addGarbageObject(this); 91d1e693f2a3883dacf213aa2b477540c57b53b714Chris Lattner 92bded132d00ed626a6541b67ad101ef0fd47d3491Chris Lattner InstList.setParent(parent); 93d1e693f2a3883dacf213aa2b477540c57b53b714Chris Lattner 94d1e693f2a3883dacf213aa2b477540c57b53b714Chris Lattner if (getParent()) 95d1e693f2a3883dacf213aa2b477540c57b53b714Chris Lattner LeakDetector::removeGarbageObject(this); 96bded132d00ed626a6541b67ad101ef0fd47d3491Chris Lattner} 97bded132d00ed626a6541b67ad101ef0fd47d3491Chris Lattner 98009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// Specialize setName to take care of symbol table majik 99697954c15da58bd8b186dbafdedd8b06db770201Chris Lattnervoid BasicBlock::setName(const std::string &name, SymbolTable *ST) { 100b7653df0853f06112b741be09f1b7ae5a6aa6fdeChris Lattner Function *P; 1016e6026b46569b01f8f6d4dcdb6c899c3a9c76b3eChris Lattner assert((ST == 0 || (!getParent() || ST == &getParent()->getSymbolTable())) && 1026892b126e3d3b90f13744cc1a7c83fd7f8d615f2Chris Lattner "Invalid symtab argument!"); 1036e6026b46569b01f8f6d4dcdb6c899c3a9c76b3eChris Lattner if ((P = getParent()) && hasName()) P->getSymbolTable().remove(this); 104009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner Value::setName(name); 1056e6026b46569b01f8f6d4dcdb6c899c3a9c76b3eChris Lattner if (P && hasName()) P->getSymbolTable().insert(this); 106009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner} 107009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 1084b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattnervoid BasicBlock::removeFromParent() { 1094b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattner getParent()->getBasicBlockList().remove(this); 1104b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattner} 1114b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattner 1124b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattnervoid BasicBlock::eraseFromParent() { 1134b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattner getParent()->getBasicBlockList().erase(this); 1144b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattner} 1154b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattner 1164b83380f330b1c77bb9b4ad8f63bdcf1a596afd6Chris Lattner 117009505452b713ed2e3a8e99c5545a6e721c65495Chris LattnerTerminatorInst *BasicBlock::getTerminator() { 118009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner if (InstList.empty()) return 0; 1197e70829632f82de15db187845666aaca6e04b792Chris Lattner return dyn_cast<TerminatorInst>(&InstList.back()); 120009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner} 121009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 122009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattnerconst TerminatorInst *const BasicBlock::getTerminator() const { 123009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner if (InstList.empty()) return 0; 1247e70829632f82de15db187845666aaca6e04b792Chris Lattner return dyn_cast<TerminatorInst>(&InstList.back()); 125009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner} 126009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 127009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattnervoid BasicBlock::dropAllReferences() { 1287e70829632f82de15db187845666aaca6e04b792Chris Lattner for(iterator I = begin(), E = end(); I != E; ++I) 1297e70829632f82de15db187845666aaca6e04b792Chris Lattner I->dropAllReferences(); 130009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner} 131009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 132ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner/// getSinglePredecessor - If this basic block has a single predecessor block, 133ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner/// return the block, otherwise return a null pointer. 134ad993cbb77b26b36cee938686b3377c0d92abd5eChris LattnerBasicBlock *BasicBlock::getSinglePredecessor() { 135ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner pred_iterator PI = pred_begin(this), E = pred_end(this); 136ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner if (PI == E) return 0; // No preds. 137ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner BasicBlock *ThePred = *PI; 138ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner ++PI; 139ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner return (PI == E) ? ThePred : 0 /*multiple preds*/; 140ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner} 141ad993cbb77b26b36cee938686b3377c0d92abd5eChris Lattner 142b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner// removePredecessor - This method is used to notify a BasicBlock that the 143b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner// specified Predecessor of the block is no longer able to reach it. This is 144b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner// actually not used to update the Predecessor list, but is actually used to 145b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner// update the PHI nodes that reside in the block. Note that this should be 146b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner// called while the predecessor still refers to this block. 147b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner// 148b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattnervoid BasicBlock::removePredecessor(BasicBlock *Pred) { 1491f21ef1511ce003fc177121b980e783b83992f82Chris Lattner assert((hasNUsesOrMore(16)||// Reduce cost of this assertion for complex CFGs. 15035f0aecdb012ba150953f6f3a98862be9c72d265Chris Lattner find(pred_begin(this), pred_end(this), Pred) != pred_end(this)) && 151b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner "removePredecessor: BB is not a predecessor!"); 15235f0aecdb012ba150953f6f3a98862be9c72d265Chris Lattner 153f23586c7efe615d061c00c24cf62f03f7962776fChris Lattner if (InstList.empty()) return; 154a9e7781b3b8e457946491529816feab73c66d774Chris Lattner PHINode *APN = dyn_cast<PHINode>(&front()); 155a9e7781b3b8e457946491529816feab73c66d774Chris Lattner if (!APN) return; // Quick exit. 156b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner 157b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner // If there are exactly two predecessors, then we want to nuke the PHI nodes 158a9e7781b3b8e457946491529816feab73c66d774Chris Lattner // altogether. However, we cannot do this, if this in this case: 15987a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // 16087a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // Loop: 16187a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // %x = phi [X, Loop] 16287a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // %x2 = add %x, 1 ;; This would become %x2 = add %x2, 1 16387a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // br Loop ;; %x2 does not dominate all uses 16487a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // 16587a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // This is because the PHI node input is actually taken from the predecessor 16687a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // basic block. The only case this can happen is with a self loop, so we 16787a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // check for this case explicitly now. 16887a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // 169a9e7781b3b8e457946491529816feab73c66d774Chris Lattner unsigned max_idx = APN->getNumIncomingValues(); 170b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner assert(max_idx != 0 && "PHI Node in block with 0 predecessors!?!?!"); 17187a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner if (max_idx == 2) { 172a9e7781b3b8e457946491529816feab73c66d774Chris Lattner BasicBlock *Other = APN->getIncomingBlock(APN->getIncomingBlock(0) == Pred); 17387a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner 17487a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner // Disable PHI elimination! 17587a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner if (this == Other) max_idx = 3; 17687a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner } 17787a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner 178b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner if (max_idx <= 2) { // <= Two predecessors BEFORE I remove one? 179b00c582b6d40e6b9ff2d1ed4f5eaf7930e792aceChris Lattner // Yup, loop through and nuke the PHI nodes 1807e70829632f82de15db187845666aaca6e04b792Chris Lattner while (PHINode *PN = dyn_cast<PHINode>(&front())) { 181b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner PN->removeIncomingValue(Pred); // Remove the predecessor first... 182b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner 183b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner // If the PHI _HAD_ two uses, replace PHI node with its now *single* value 184dee430d26e14a3d7c8d86688d49ac8b116aa044fChris Lattner if (max_idx == 2) { 18502a78cf7eacf97f2c9584e29d02f77612aead35fChris Lattner if (PN->getOperand(0) != PN) 18602a78cf7eacf97f2c9584e29d02f77612aead35fChris Lattner PN->replaceAllUsesWith(PN->getOperand(0)); 18702a78cf7eacf97f2c9584e29d02f77612aead35fChris Lattner else 18802a78cf7eacf97f2c9584e29d02f77612aead35fChris Lattner // We are left with an infinite loop with no entries: kill the PHI. 18902a78cf7eacf97f2c9584e29d02f77612aead35fChris Lattner PN->replaceAllUsesWith(Constant::getNullValue(PN->getType())); 190dee430d26e14a3d7c8d86688d49ac8b116aa044fChris Lattner getInstList().pop_front(); // Remove the PHI node 191dee430d26e14a3d7c8d86688d49ac8b116aa044fChris Lattner } 192dee430d26e14a3d7c8d86688d49ac8b116aa044fChris Lattner 193dee430d26e14a3d7c8d86688d49ac8b116aa044fChris Lattner // If the PHI node already only had one entry, it got deleted by 194dee430d26e14a3d7c8d86688d49ac8b116aa044fChris Lattner // removeIncomingValue. 195b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner } 196b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner } else { 197b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner // Okay, now we know that we need to remove predecessor #pred_idx from all 198b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner // PHI nodes. Iterate over each PHI node fixing them up 199f878218c972dc570eb50e739c2ee2b9dd75ee5ddChris Lattner PHINode *PN; 2009bf2a926cbdf05c5b412ec35e72908a08a4cf34bChris Lattner for (iterator II = begin(); (PN = dyn_cast<PHINode>(II)); ++II) 20187a09b10f8e03182e9edcb6e9ee8386f4a5d8daeChris Lattner PN->removeIncomingValue(Pred); 202b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner } 203b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner} 204b47af25099cac5c59795d6f1eb3b7cf9f962b32fChris Lattner 205009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 206009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// splitBasicBlock - This splits a basic block into two at the specified 207009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// instruction. Note that all instructions BEFORE the specified iterator stay 208009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// as part of the original basic block, an unconditional branch is added to 209009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// the new BB, and the rest of the instructions in the BB are moved to the new 210009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// BB, including the old terminator. This invalidates the iterator. 211009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// 212009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// Note that this only works on well formed basic blocks (must have a 213009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// terminator), and 'I' must not be the end of instruction list (which would 214009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// cause a degenerate basic block to be formed, having a terminator inside of 215009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// the basic block). 216009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner// 2174bd4aa5e3c41c0fc803e960252bb6fe75b804b1dChris LattnerBasicBlock *BasicBlock::splitBasicBlock(iterator I, const std::string &BBName) { 218009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner assert(getTerminator() && "Can't use splitBasicBlock on degenerate BB!"); 219009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner assert(I != InstList.end() && 220009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner "Trying to get me to create degenerate basic block!"); 221009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 2224f05611ed948ed1fb3e861d178aae18bd025ce1cChris Lattner BasicBlock *New = new BasicBlock(BBName, getParent(), getNext()); 223009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 224f2c3106866137b0c06e99f453a83d9558c0c6934Chris Lattner // Move all of the specified instructions from the original basic block into 225f2c3106866137b0c06e99f453a83d9558c0c6934Chris Lattner // the new basic block. 226f2c3106866137b0c06e99f453a83d9558c0c6934Chris Lattner New->getInstList().splice(New->end(), this->getInstList(), I, end()); 227009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner 228009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner // Add a branch instruction to the newly formed basic block. 229108e4ab159b59a616b0868e396dc7ddc1fb48616Chris Lattner new BranchInst(New, this); 230e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner 231e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner // Now we must loop through all of the successors of the New block (which 232e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner // _were_ the successors of the 'this' block), and update any PHI nodes in 233e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner // successors. If there were PHI nodes in the successors, then they need to 234e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner // know that incoming branches will be from New, not from Old. 235e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner // 2361c9ab515de41707c8e04a51694a50479068e891dChris Lattner for (succ_iterator I = succ_begin(New), E = succ_end(New); I != E; ++I) { 237e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner // Loop over any phi nodes in the basic block, updating the BB field of 238e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner // incoming values... 239e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner BasicBlock *Successor = *I; 240f878218c972dc570eb50e739c2ee2b9dd75ee5ddChris Lattner PHINode *PN; 241e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner for (BasicBlock::iterator II = Successor->begin(); 2429bf2a926cbdf05c5b412ec35e72908a08a4cf34bChris Lattner (PN = dyn_cast<PHINode>(II)); ++II) { 243e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner int IDX = PN->getBasicBlockIndex(this); 244e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner while (IDX != -1) { 245e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner PN->setIncomingBlock((unsigned)IDX, New); 246e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner IDX = PN->getBasicBlockIndex(this); 247e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner } 248e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner } 249e8e320d2faa997605c76a7c3ab9e9b4fb578e8c0Chris Lattner } 250009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner return New; 251009505452b713ed2e3a8e99c5545a6e721c65495Chris Lattner} 252