X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FBasicBlock.cpp;h=f23a49696e479693c6f0f7326bd89e61cef1937d;hb=d04a8d4b33ff316ca4cf961e06c9e312eff8e64f;hp=b00ce51f2f71e59f9876d156d0632f99e2651013;hpb=f8485c643412dbff46fe87ea2867445169a5c28e;p=oota-llvm.git diff --git a/lib/VMCore/BasicBlock.cpp b/lib/VMCore/BasicBlock.cpp index b00ce51f2f7..f23a49696e4 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. @@ -12,91 +12,72 @@ //===----------------------------------------------------------------------===// #include "llvm/BasicBlock.h" -#include "llvm/iTerminators.h" -#include "llvm/Type.h" -#include "llvm/Support/CFG.h" -#include "llvm/Constant.h" -#include "llvm/iPHINode.h" -#include "llvm/SymbolTable.h" -#include "Support/LeakDetector.h" #include "SymbolTableListTraitsImpl.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/Constants.h" +#include "llvm/Instructions.h" +#include "llvm/IntrinsicInst.h" +#include "llvm/LLVMContext.h" +#include "llvm/Support/CFG.h" +#include "llvm/Support/LeakDetector.h" +#include "llvm/Type.h" #include +using namespace llvm; -namespace llvm { - -// 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) { - // 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)); - } -}; - -Instruction *ilist_traits::createNode() { - return new DummyInst(); +ValueSymbolTable *BasicBlock::getValueSymbolTable() { + if (Function *F = getParent()) + return &F->getValueSymbolTable(); + return 0; } -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 ctor - If the function parameter is specified, the basic block is -// automatically inserted at the end of the function. -// -BasicBlock::BasicBlock(const std::string &name, Function *Parent) - : Value(Type::LabelTy, Value::BasicBlockVal, name) { - // Initialize the instlist... - InstList.setItemParent(this); - - // Make sure that we get added to a function - LeakDetector::addGarbageObject(this); - - if (Parent) - Parent->getBasicBlockList().push_back(this); -} - -/// BasicBlock ctor - If the InsertBefore parameter is specified, the basic -/// block is automatically inserted right before the specified block. -/// -BasicBlock::BasicBlock(const std::string &Name, BasicBlock *InsertBefore) - : Value(Type::LabelTy, Value::BasicBlockVal, Name) { - // Initialize the instlist... - InstList.setItemParent(this); +BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent, + BasicBlock *InsertBefore) + : Value(Type::getLabelTy(C), Value::BasicBlockVal), Parent(0) { // Make sure that we get added to a function LeakDetector::addGarbageObject(this); if (InsertBefore) { - assert(InsertBefore->getParent() && - "Cannot insert block before another block that is not embedded into" - " a function yet!"); - InsertBefore->getParent()->getBasicBlockList().insert(InsertBefore, this); + assert(NewParent && + "Cannot insert block before another block with no function!"); + 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(); } @@ -105,70 +86,145 @@ 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); +} + +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(); } -// hasConstantReferences() - This predicate is true if there is a -// reference to this basic block in the constant pool for this method. For -// example, if a block is reached through a switch table, that table resides -// in the constant pool, and the basic block is reference from it. -// -bool BasicBlock::hasConstantReferences() const { - for (use_const_iterator I = use_begin(), E = use_end(); I != E; ++I) - if (isa((Value*)*I)) - return true; - - return false; +/// 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*/; } -// 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) { - assert(find(pred_begin(this), pred_end(this), Pred) != pred_end(this) && - "removePredecessor: BB is not a predecessor!"); - if (!isa(front())) return; // Quick exit. +/// 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; +} - pred_iterator PI(pred_begin(this)), EI(pred_end(this)); - unsigned max_idx; +/// 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!"); - // Loop over the rest of the predecessors until we run out, or until we find - // out that there are more than 2 predecessors. - for (max_idx = 0; PI != EI && max_idx < 3; ++PI, ++max_idx) /*empty*/; + if (InstList.empty()) return; + PHINode *APN = dyn_cast(&front()); + if (!APN) return; // Quick exit. // If there are exactly two predecessors, then we want to nuke the PHI nodes - // altogether. We cannot do this, however if this in this case however: + // altogether. However, we cannot do this, if this in this case: // // Loop: // %x = phi [X, Loop] @@ -176,30 +232,32 @@ 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) { - PI = pred_begin(this); - BasicBlock *Other = *PI == Pred ? *++PI : *PI; + BasicBlock *Other = APN->getIncomingBlock(APN->getIncomingBlock(0) == Pred); // Disable PHI elimination! 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 } @@ -209,41 +267,50 @@ void BasicBlock::removePredecessor(BasicBlock *Pred) { } else { // Okay, now we know that we need to remove predecessor #pred_idx from all // PHI nodes. Iterate over each PHI node fixing them up - for (iterator II = begin(); PHINode *PN = dyn_cast(II); ++II) - PN->removeIncomingValue(Pred); + PHINode *PN; + 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()); + BasicBlock *InsertBefore = llvm::next(Function::iterator(this)) + .getNodePtrUnchecked(); + BasicBlock *New = BasicBlock::Create(getContext(), BBName, + getParent(), InsertBefore); - // Go from the end of the basic block through to the iterator pointer, moving - // to the new basic block... - Instruction *Inst = 0; - do { - iterator EndIt = end(); - Inst = InstList.remove(--EndIt); // Remove from end - New->InstList.push_front(Inst); // Add to front - } while (Inst != &*I); // Loop until we move the specified instruction. + // 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, 0, 0, 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 @@ -254,8 +321,9 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const std::string &BBName) { // Loop over any phi nodes in the basic block, updating the BB field of // incoming values... BasicBlock *Successor = *I; + PHINode *PN; for (BasicBlock::iterator II = Successor->begin(); - PHINode *PN = dyn_cast(II); ++II) { + (PN = dyn_cast(II)); ++II) { int IDX = PN->getBasicBlockIndex(this); while (IDX != -1) { PN->setIncomingBlock((unsigned)IDX, New); @@ -266,4 +334,38 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const std::string &BBName) { return New; } -} // End llvm namespace +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()); +} +const LandingPadInst *BasicBlock::getLandingPadInst() const { + return dyn_cast(getFirstNonPHI()); +}