X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FBasicBlock.cpp;h=d0aa275c8fe27dff846c4ac2d4c256937f525743;hb=9c6cdf4c1c82842a97e02bef4cef2431ad2e61a3;hp=b22a54162b908d9b8deddef093bcd7872cb753bc;hpb=1f21ef1511ce003fc177121b980e783b83992f82;p=oota-llvm.git diff --git a/lib/VMCore/BasicBlock.cpp b/lib/VMCore/BasicBlock.cpp index b22a54162b9..d0aa275c8fe 100644 --- a/lib/VMCore/BasicBlock.cpp +++ b/lib/VMCore/BasicBlock.cpp @@ -1,10 +1,10 @@ //===-- BasicBlock.cpp - Implement BasicBlock related methods -------------===// -// +// // The LLVM Compiler Infrastructure // -// This file was developed by the LLVM research group and is distributed under -// the University of Illinois Open Source License. See LICENSE.TXT for details. -// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// //===----------------------------------------------------------------------===// // // This file implements the BasicBlock class for the VMCore library. @@ -12,74 +12,71 @@ //===----------------------------------------------------------------------===// #include "llvm/BasicBlock.h" -#include "llvm/Constant.h" +#include "llvm/Constants.h" #include "llvm/Instructions.h" +#include "llvm/IntrinsicInst.h" +#include "llvm/LLVMContext.h" #include "llvm/Type.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/Support/CFG.h" -#include "llvm/SymbolTable.h" #include "llvm/Support/LeakDetector.h" #include "SymbolTableListTraitsImpl.h" #include using namespace llvm; -namespace { - /// DummyInst - An instance of this class is used to mark the end of the - /// instruction list. This is not a real instruction. - struct DummyInst : public Instruction { - DummyInst() : Instruction(Type::VoidTy, OtherOpsEnd, 0, 0) { - // This should not be garbage monitored. - LeakDetector::removeGarbageObject(this); - } - - virtual Instruction *clone() const { - assert(0 && "Cannot clone EOL");abort(); - return 0; - } - virtual const char *getOpcodeName() const { return "*end-of-list-inst*"; } - - // Methods for support type inquiry through isa, cast, and dyn_cast... - static inline bool classof(const DummyInst *) { return true; } - static inline bool classof(const Instruction *I) { - return I->getOpcode() == OtherOpsEnd; - } - static inline bool classof(const Value *V) { - return isa(V) && classof(cast(V)); - } - }; +ValueSymbolTable *BasicBlock::getValueSymbolTable() { + if (Function *F = getParent()) + return &F->getValueSymbolTable(); + return 0; } -Instruction *ilist_traits::createSentinel() { - return new DummyInst(); -} -iplist &ilist_traits::getList(BasicBlock *BB) { - return BB->getInstList(); +LLVMContext &BasicBlock::getContext() const { + return getType()->getContext(); } // Explicit instantiation of SymbolTableListTraits since some of the methods // are not in the public header file... -template class SymbolTableListTraits; +template class llvm::SymbolTableListTraits; -BasicBlock::BasicBlock(const std::string &Name, Function *Parent, +BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent, BasicBlock *InsertBefore) - : Value(Type::LabelTy, Value::BasicBlockVal, Name) { - // Initialize the instlist... - InstList.setItemParent(this); + : Value(Type::getLabelTy(C), Value::BasicBlockVal), Parent(0) { // Make sure that we get added to a function LeakDetector::addGarbageObject(this); if (InsertBefore) { - assert(Parent && + assert(NewParent && "Cannot insert block before another block with no function!"); - Parent->getBasicBlockList().insert(InsertBefore, this); - } else if (Parent) { - Parent->getBasicBlockList().push_back(this); + NewParent->getBasicBlockList().insert(InsertBefore, this); + } else if (NewParent) { + NewParent->getBasicBlockList().push_back(this); } + + setName(Name); } BasicBlock::~BasicBlock() { + // If the address of the block is taken and it is being deleted (e.g. because + // it is dead), this means that there is either a dangling constant expr + // hanging off the block, or an undefined use of the block (source code + // expecting the address of a label to keep the block alive even though there + // is no indirect branch). Handle these cases by zapping the BlockAddress + // nodes. There are no other possible uses at this point. + if (hasAddressTaken()) { + assert(!use_empty() && "There should be at least one blockaddress!"); + Constant *Replacement = + ConstantInt::get(llvm::Type::getInt32Ty(getContext()), 1); + while (!use_empty()) { + BlockAddress *BA = cast(use_back()); + BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement, + BA->getType())); + BA->destroyConstant(); + } + } + assert(getParent() == 0 && "BasicBlock still linked into the program!"); dropAllReferences(); InstList.clear(); @@ -89,22 +86,13 @@ void BasicBlock::setParent(Function *parent) { if (getParent()) LeakDetector::addGarbageObject(this); - InstList.setParent(parent); + // Set Parent=parent, updating instruction symtab entries as appropriate. + InstList.setSymTabObject(&Parent, parent); if (getParent()) LeakDetector::removeGarbageObject(this); } -// Specialize setName to take care of symbol table majik -void BasicBlock::setName(const std::string &name, SymbolTable *ST) { - Function *P; - assert((ST == 0 || (!getParent() || ST == &getParent()->getSymbolTable())) && - "Invalid symtab argument!"); - if ((P = getParent()) && hasName()) P->getSymbolTable().remove(this); - Value::setName(name); - if (P && hasName()) P->getSymbolTable().insert(this); -} - void BasicBlock::removeFromParent() { getParent()->getBasicBlockList().remove(this); } @@ -113,32 +101,123 @@ void BasicBlock::eraseFromParent() { getParent()->getBasicBlockList().erase(this); } +/// moveBefore - Unlink this basic block from its current function and +/// insert it into the function that MovePos lives in, right before MovePos. +void BasicBlock::moveBefore(BasicBlock *MovePos) { + MovePos->getParent()->getBasicBlockList().splice(MovePos, + getParent()->getBasicBlockList(), this); +} + +/// moveAfter - Unlink this basic block from its current function and +/// insert it into the function that MovePos lives in, right after MovePos. +void BasicBlock::moveAfter(BasicBlock *MovePos) { + Function::iterator I = MovePos; + MovePos->getParent()->getBasicBlockList().splice(++I, + getParent()->getBasicBlockList(), this); +} + TerminatorInst *BasicBlock::getTerminator() { if (InstList.empty()) return 0; return dyn_cast(&InstList.back()); } -const TerminatorInst *const BasicBlock::getTerminator() const { +const TerminatorInst *BasicBlock::getTerminator() const { if (InstList.empty()) return 0; return dyn_cast(&InstList.back()); } +Instruction* BasicBlock::getFirstNonPHI() { + BasicBlock::iterator i = begin(); + // All valid basic blocks should have a terminator, + // which is not a PHINode. If we have an invalid basic + // block we'll get an assertion failure when dereferencing + // a past-the-end iterator. + while (isa(i)) ++i; + return &*i; +} + +Instruction* BasicBlock::getFirstNonPHIOrDbg() { + BasicBlock::iterator i = begin(); + // All valid basic blocks should have a terminator, + // which is not a PHINode. If we have an invalid basic + // block we'll get an assertion failure when dereferencing + // a past-the-end iterator. + while (isa(i) || isa(i)) ++i; + return &*i; +} + +Instruction* BasicBlock::getFirstNonPHIOrDbgOrLifetime() { + // All valid basic blocks should have a terminator, + // which is not a PHINode. If we have an invalid basic + // block we'll get an assertion failure when dereferencing + // a past-the-end iterator. + BasicBlock::iterator i = begin(); + for (;; ++i) { + if (isa(i) || isa(i)) + continue; + + const IntrinsicInst *II = dyn_cast(i); + if (!II) + break; + if (II->getIntrinsicID() != Intrinsic::lifetime_start && + II->getIntrinsicID() != Intrinsic::lifetime_end) + break; + } + return &*i; +} + +BasicBlock::iterator BasicBlock::getFirstInsertionPt() { + iterator InsertPt = getFirstNonPHI(); + if (isa(InsertPt)) ++InsertPt; + return InsertPt; +} + void BasicBlock::dropAllReferences() { for(iterator I = begin(), E = end(); I != E; ++I) I->dropAllReferences(); } -// removePredecessor - This method is used to notify a BasicBlock that the -// specified Predecessor of the block is no longer able to reach it. This is -// actually not used to update the Predecessor list, but is actually used to -// update the PHI nodes that reside in the block. Note that this should be -// called while the predecessor still refers to this block. -// -void BasicBlock::removePredecessor(BasicBlock *Pred) { +/// getSinglePredecessor - If this basic block has a single predecessor block, +/// return the block, otherwise return a null pointer. +BasicBlock *BasicBlock::getSinglePredecessor() { + pred_iterator PI = pred_begin(this), E = pred_end(this); + if (PI == E) return 0; // No preds. + BasicBlock *ThePred = *PI; + ++PI; + return (PI == E) ? ThePred : 0 /*multiple preds*/; +} + +/// getUniquePredecessor - If this basic block has a unique predecessor block, +/// return the block, otherwise return a null pointer. +/// Note that unique predecessor doesn't mean single edge, there can be +/// multiple edges from the unique predecessor to this block (for example +/// a switch statement with multiple cases having the same destination). +BasicBlock *BasicBlock::getUniquePredecessor() { + pred_iterator PI = pred_begin(this), E = pred_end(this); + if (PI == E) return 0; // No preds. + BasicBlock *PredBB = *PI; + ++PI; + for (;PI != E; ++PI) { + if (*PI != PredBB) + return 0; + // The same predecessor appears multiple times in the predecessor list. + // This is OK. + } + return PredBB; +} + +/// removePredecessor - This method is used to notify a BasicBlock that the +/// specified Predecessor of the block is no longer able to reach it. This is +/// actually not used to update the Predecessor list, but is actually used to +/// update the PHI nodes that reside in the block. Note that this should be +/// called while the predecessor still refers to this block. +/// +void BasicBlock::removePredecessor(BasicBlock *Pred, + bool DontDeleteUselessPHIs) { assert((hasNUsesOrMore(16)||// Reduce cost of this assertion for complex CFGs. find(pred_begin(this), pred_end(this), Pred) != pred_end(this)) && - "removePredecessor: BB is not a predecessor!"); + "removePredecessor: BB is not a predecessor!"); if (InstList.empty()) return; PHINode *APN = dyn_cast(&front()); @@ -153,9 +232,9 @@ void BasicBlock::removePredecessor(BasicBlock *Pred) { // br Loop ;; %x2 does not dominate all uses // // This is because the PHI node input is actually taken from the predecessor - // basic block. The only case this can happen is with a self loop, so we + // basic block. The only case this can happen is with a self loop, so we // check for this case explicitly now. - // + // unsigned max_idx = APN->getNumIncomingValues(); assert(max_idx != 0 && "PHI Node in block with 0 predecessors!?!?!"); if (max_idx == 2) { @@ -165,18 +244,20 @@ void BasicBlock::removePredecessor(BasicBlock *Pred) { if (this == Other) max_idx = 3; } - if (max_idx <= 2) { // <= Two predecessors BEFORE I remove one? + // <= Two predecessors BEFORE I remove one? + if (max_idx <= 2 && !DontDeleteUselessPHIs) { // Yup, loop through and nuke the PHI nodes while (PHINode *PN = dyn_cast(&front())) { - PN->removeIncomingValue(Pred); // Remove the predecessor first... + // Remove the predecessor first. + PN->removeIncomingValue(Pred, !DontDeleteUselessPHIs); // If the PHI _HAD_ two uses, replace PHI node with its now *single* value if (max_idx == 2) { - if (PN->getOperand(0) != PN) - PN->replaceAllUsesWith(PN->getOperand(0)); + if (PN->getIncomingValue(0) != PN) + PN->replaceAllUsesWith(PN->getIncomingValue(0)); else // We are left with an infinite loop with no entries: kill the PHI. - PN->replaceAllUsesWith(Constant::getNullValue(PN->getType())); + PN->replaceAllUsesWith(UndefValue::get(PN->getType())); getInstList().pop_front(); // Remove the PHI node } @@ -187,36 +268,49 @@ void BasicBlock::removePredecessor(BasicBlock *Pred) { // Okay, now we know that we need to remove predecessor #pred_idx from all // PHI nodes. Iterate over each PHI node fixing them up PHINode *PN; - for (iterator II = begin(); (PN = dyn_cast(II)); ++II) - PN->removeIncomingValue(Pred); + for (iterator II = begin(); (PN = dyn_cast(II)); ) { + ++II; + PN->removeIncomingValue(Pred, false); + // If all incoming values to the Phi are the same, we can replace the Phi + // with that value. + Value* PNV = 0; + if (!DontDeleteUselessPHIs && (PNV = PN->hasConstantValue())) + if (PNV != PN) { + PN->replaceAllUsesWith(PNV); + PN->eraseFromParent(); + } + } } } -// splitBasicBlock - This splits a basic block into two at the specified -// instruction. Note that all instructions BEFORE the specified iterator stay -// as part of the original basic block, an unconditional branch is added to -// the new BB, and the rest of the instructions in the BB are moved to the new -// BB, including the old terminator. This invalidates the iterator. -// -// Note that this only works on well formed basic blocks (must have a -// terminator), and 'I' must not be the end of instruction list (which would -// cause a degenerate basic block to be formed, having a terminator inside of -// the basic block). -// -BasicBlock *BasicBlock::splitBasicBlock(iterator I, const std::string &BBName) { +/// splitBasicBlock - This splits a basic block into two at the specified +/// instruction. Note that all instructions BEFORE the specified iterator stay +/// as part of the original basic block, an unconditional branch is added to +/// the new BB, and the rest of the instructions in the BB are moved to the new +/// BB, including the old terminator. This invalidates the iterator. +/// +/// Note that this only works on well formed basic blocks (must have a +/// terminator), and 'I' must not be the end of instruction list (which would +/// cause a degenerate basic block to be formed, having a terminator inside of +/// the basic block). +/// +BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName) { assert(getTerminator() && "Can't use splitBasicBlock on degenerate BB!"); - assert(I != InstList.end() && - "Trying to get me to create degenerate basic block!"); + assert(I != InstList.end() && + "Trying to get me to create degenerate basic block!"); - BasicBlock *New = new BasicBlock(BBName, getParent(), getNext()); + BasicBlock *InsertBefore = llvm::next(Function::iterator(this)) + .getNodePtrUnchecked(); + BasicBlock *New = BasicBlock::Create(getContext(), BBName, + getParent(), InsertBefore); // Move all of the specified instructions from the original basic block into // the new basic block. New->getInstList().splice(New->end(), this->getInstList(), I, end()); // Add a branch instruction to the newly formed basic block. - new BranchInst(New, this); + BranchInst::Create(New, this); // Now we must loop through all of the successors of the New block (which // _were_ the successors of the 'this' block), and update any PHI nodes in @@ -239,3 +333,36 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const std::string &BBName) { } return New; } + +void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) { + TerminatorInst *TI = getTerminator(); + if (!TI) + // Cope with being called on a BasicBlock that doesn't have a terminator + // yet. Clang's CodeGenFunction::EmitReturnBlock() likes to do this. + return; + for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) { + BasicBlock *Succ = TI->getSuccessor(i); + // N.B. Succ might not be a complete BasicBlock, so don't assume + // that it ends with a non-phi instruction. + for (iterator II = Succ->begin(), IE = Succ->end(); II != IE; ++II) { + PHINode *PN = dyn_cast(II); + if (!PN) + break; + int i; + while ((i = PN->getBasicBlockIndex(this)) >= 0) + PN->setIncomingBlock(i, New); + } + } +} + +/// isLandingPad - Return true if this basic block is a landing pad. I.e., it's +/// the destination of the 'unwind' edge of an invoke instruction. +bool BasicBlock::isLandingPad() const { + return isa(getFirstNonPHI()); +} + +/// getLandingPadInst() - Return the landingpad instruction associated with +/// the landing pad. +LandingPadInst *BasicBlock::getLandingPadInst() { + return dyn_cast(getFirstNonPHI()); +}