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author | Owen Anderson <resistor@mac.com> | 2007-11-14 02:33:58 +0000 |
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committer | Owen Anderson <resistor@mac.com> | 2007-11-14 02:33:58 +0000 |
commit | 019b92a70c11319f5ab96c9f5e66e4e111a972f8 (patch) | |
tree | fd0d99f80ea76706e99493608a230360ec8d5ddb /lib/Analysis/LoopInfo.cpp | |
parent | ffb15de60e839635d8628b0f4543638239bee39a (diff) | |
download | external_llvm-019b92a70c11319f5ab96c9f5e66e4e111a972f8.zip external_llvm-019b92a70c11319f5ab96c9f5e66e4e111a972f8.tar.gz external_llvm-019b92a70c11319f5ab96c9f5e66e4e111a972f8.tar.bz2 |
Start the process of making MachineLoopInfo possible by templating Loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44097 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis/LoopInfo.cpp')
-rw-r--r-- | lib/Analysis/LoopInfo.cpp | 396 |
1 files changed, 0 insertions, 396 deletions
diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp index 09dca27..20ca892 100644 --- a/lib/Analysis/LoopInfo.cpp +++ b/lib/Analysis/LoopInfo.cpp @@ -34,69 +34,9 @@ X("loops", "Natural Loop Construction", true); //===----------------------------------------------------------------------===// // Loop implementation // -bool Loop::contains(const BasicBlock *BB) const { - return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end(); -} - -bool Loop::isLoopExit(const BasicBlock *BB) const { - for (succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB); - SI != SE; ++SI) { - if (!contains(*SI)) - return true; - } - return false; -} /// getNumBackEdges - Calculate the number of back edges to the loop header. /// -unsigned Loop::getNumBackEdges() const { - unsigned NumBackEdges = 0; - BasicBlock *H = getHeader(); - - for (pred_iterator I = pred_begin(H), E = pred_end(H); I != E; ++I) - if (contains(*I)) - ++NumBackEdges; - - return NumBackEdges; -} - -/// isLoopInvariant - Return true if the specified value is loop invariant -/// -bool Loop::isLoopInvariant(Value *V) const { - if (Instruction *I = dyn_cast<Instruction>(V)) - return !contains(I->getParent()); - return true; // All non-instructions are loop invariant -} - -void Loop::print(std::ostream &OS, unsigned Depth) const { - OS << std::string(Depth*2, ' ') << "Loop Containing: "; - - for (unsigned i = 0; i < getBlocks().size(); ++i) { - if (i) OS << ","; - WriteAsOperand(OS, getBlocks()[i], false); - } - OS << "\n"; - - for (iterator I = begin(), E = end(); I != E; ++I) - (*I)->print(OS, Depth+2); -} - -/// verifyLoop - Verify loop structure -void Loop::verifyLoop() const { -#ifndef NDEBUG - assert (getHeader() && "Loop header is missing"); - assert (getLoopPreheader() && "Loop preheader is missing"); - assert (getLoopLatch() && "Loop latch is missing"); - for (std::vector<Loop*>::const_iterator I = SubLoops.begin(), E = SubLoops.end(); - I != E; ++I) - (*I)->verifyLoop(); -#endif -} - -void Loop::dump() const { - print(cerr); -} - //===----------------------------------------------------------------------===// // LoopInfo implementation @@ -341,341 +281,5 @@ void LoopInfo::removeBlock(BasicBlock *BB) { } } - -//===----------------------------------------------------------------------===// -// APIs for simple analysis of the loop. -// - -/// getExitingBlocks - Return all blocks inside the loop that have successors -/// outside of the loop. These are the blocks _inside of the current loop_ -/// which branch out. The returned list is always unique. -/// -void Loop::getExitingBlocks(SmallVectorImpl<BasicBlock*> &ExitingBlocks) const { - // Sort the blocks vector so that we can use binary search to do quick - // lookups. - SmallVector<BasicBlock*, 128> LoopBBs(block_begin(), block_end()); - std::sort(LoopBBs.begin(), LoopBBs.end()); - - for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(), - BE = Blocks.end(); BI != BE; ++BI) - for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) - if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) { - // Not in current loop? It must be an exit block. - ExitingBlocks.push_back(*BI); - break; - } -} - -/// getExitBlocks - Return all of the successor blocks of this loop. These -/// are the blocks _outside of the current loop_ which are branched to. -/// -void Loop::getExitBlocks(SmallVectorImpl<BasicBlock*> &ExitBlocks) const { - // Sort the blocks vector so that we can use binary search to do quick - // lookups. - SmallVector<BasicBlock*, 128> LoopBBs(block_begin(), block_end()); - std::sort(LoopBBs.begin(), LoopBBs.end()); - - for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(), - BE = Blocks.end(); BI != BE; ++BI) - for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) - if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) - // Not in current loop? It must be an exit block. - ExitBlocks.push_back(*I); -} - -/// getUniqueExitBlocks - Return all unique successor blocks of this loop. These -/// are the blocks _outside of the current loop_ which are branched to. This -/// assumes that loop is in canonical form. -// -void Loop::getUniqueExitBlocks(SmallVectorImpl<BasicBlock*> &ExitBlocks) const { - // Sort the blocks vector so that we can use binary search to do quick - // lookups. - SmallVector<BasicBlock*, 128> LoopBBs(block_begin(), block_end()); - std::sort(LoopBBs.begin(), LoopBBs.end()); - - std::vector<BasicBlock*> switchExitBlocks; - - for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(), - BE = Blocks.end(); BI != BE; ++BI) { - - BasicBlock *current = *BI; - switchExitBlocks.clear(); - - for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) { - if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) - // If block is inside the loop then it is not a exit block. - continue; - - pred_iterator PI = pred_begin(*I); - BasicBlock *firstPred = *PI; - - // If current basic block is this exit block's first predecessor - // then only insert exit block in to the output ExitBlocks vector. - // This ensures that same exit block is not inserted twice into - // ExitBlocks vector. - if (current != firstPred) - continue; - - // If a terminator has more then two successors, for example SwitchInst, - // then it is possible that there are multiple edges from current block - // to one exit block. - if (current->getTerminator()->getNumSuccessors() <= 2) { - ExitBlocks.push_back(*I); - continue; - } - - // In case of multiple edges from current block to exit block, collect - // only one edge in ExitBlocks. Use switchExitBlocks to keep track of - // duplicate edges. - if (std::find(switchExitBlocks.begin(), switchExitBlocks.end(), *I) - == switchExitBlocks.end()) { - switchExitBlocks.push_back(*I); - ExitBlocks.push_back(*I); - } - } - } -} - - -/// getLoopPreheader - If there is a preheader for this loop, return it. A -/// loop has a preheader if there is only one edge to the header of the loop -/// from outside of the loop. If this is the case, the block branching to the -/// header of the loop is the preheader node. -/// -/// This method returns null if there is no preheader for the loop. -/// -BasicBlock *Loop::getLoopPreheader() const { - // Keep track of nodes outside the loop branching to the header... - BasicBlock *Out = 0; - - // Loop over the predecessors of the header node... - BasicBlock *Header = getHeader(); - for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header); - PI != PE; ++PI) - if (!contains(*PI)) { // If the block is not in the loop... - if (Out && Out != *PI) - return 0; // Multiple predecessors outside the loop - Out = *PI; - } - - // Make sure there is only one exit out of the preheader. - assert(Out && "Header of loop has no predecessors from outside loop?"); - succ_iterator SI = succ_begin(Out); - ++SI; - if (SI != succ_end(Out)) - return 0; // Multiple exits from the block, must not be a preheader. - - // If there is exactly one preheader, return it. If there was zero, then Out - // is still null. - return Out; -} - -/// getLoopLatch - If there is a latch block for this loop, return it. A -/// latch block is the canonical backedge for a loop. A loop header in normal -/// form has two edges into it: one from a preheader and one from a latch -/// block. -BasicBlock *Loop::getLoopLatch() const { - BasicBlock *Header = getHeader(); - pred_iterator PI = pred_begin(Header), PE = pred_end(Header); - if (PI == PE) return 0; // no preds? - - BasicBlock *Latch = 0; - if (contains(*PI)) - Latch = *PI; - ++PI; - if (PI == PE) return 0; // only one pred? - - if (contains(*PI)) { - if (Latch) return 0; // multiple backedges - Latch = *PI; - } - ++PI; - if (PI != PE) return 0; // more than two preds - - return Latch; -} - -/// getCanonicalInductionVariable - Check to see if the loop has a canonical -/// induction variable: an integer recurrence that starts at 0 and increments by -/// one each time through the loop. If so, return the phi node that corresponds -/// to it. -/// -PHINode *Loop::getCanonicalInductionVariable() const { - BasicBlock *H = getHeader(); - - BasicBlock *Incoming = 0, *Backedge = 0; - pred_iterator PI = pred_begin(H); - assert(PI != pred_end(H) && "Loop must have at least one backedge!"); - Backedge = *PI++; - if (PI == pred_end(H)) return 0; // dead loop - Incoming = *PI++; - if (PI != pred_end(H)) return 0; // multiple backedges? - - if (contains(Incoming)) { - if (contains(Backedge)) - return 0; - std::swap(Incoming, Backedge); - } else if (!contains(Backedge)) - return 0; - - // Loop over all of the PHI nodes, looking for a canonical indvar. - for (BasicBlock::iterator I = H->begin(); isa<PHINode>(I); ++I) { - PHINode *PN = cast<PHINode>(I); - if (Instruction *Inc = - dyn_cast<Instruction>(PN->getIncomingValueForBlock(Backedge))) - if (Inc->getOpcode() == Instruction::Add && Inc->getOperand(0) == PN) - if (ConstantInt *CI = dyn_cast<ConstantInt>(Inc->getOperand(1))) - if (CI->equalsInt(1)) - return PN; - } - return 0; -} - -/// getCanonicalInductionVariableIncrement - Return the LLVM value that holds -/// the canonical induction variable value for the "next" iteration of the loop. -/// This always succeeds if getCanonicalInductionVariable succeeds. -/// -Instruction *Loop::getCanonicalInductionVariableIncrement() const { - if (PHINode *PN = getCanonicalInductionVariable()) { - bool P1InLoop = contains(PN->getIncomingBlock(1)); - return cast<Instruction>(PN->getIncomingValue(P1InLoop)); - } - return 0; -} - -/// getTripCount - Return a loop-invariant LLVM value indicating the number of -/// times the loop will be executed. Note that this means that the backedge of -/// the loop executes N-1 times. If the trip-count cannot be determined, this -/// returns null. -/// -Value *Loop::getTripCount() const { - // Canonical loops will end with a 'cmp ne I, V', where I is the incremented - // canonical induction variable and V is the trip count of the loop. - Instruction *Inc = getCanonicalInductionVariableIncrement(); - if (Inc == 0) return 0; - PHINode *IV = cast<PHINode>(Inc->getOperand(0)); - - BasicBlock *BackedgeBlock = - IV->getIncomingBlock(contains(IV->getIncomingBlock(1))); - - if (BranchInst *BI = dyn_cast<BranchInst>(BackedgeBlock->getTerminator())) - if (BI->isConditional()) { - if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) { - if (ICI->getOperand(0) == Inc) - if (BI->getSuccessor(0) == getHeader()) { - if (ICI->getPredicate() == ICmpInst::ICMP_NE) - return ICI->getOperand(1); - } else if (ICI->getPredicate() == ICmpInst::ICMP_EQ) { - return ICI->getOperand(1); - } - } - } - - return 0; -} - -/// isLCSSAForm - Return true if the Loop is in LCSSA form -bool Loop::isLCSSAForm() const { - // Sort the blocks vector so that we can use binary search to do quick - // lookups. - SmallPtrSet<BasicBlock*, 16> LoopBBs(block_begin(), block_end()); - - for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) { - BasicBlock *BB = *BI; - for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) - for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; - ++UI) { - BasicBlock *UserBB = cast<Instruction>(*UI)->getParent(); - if (PHINode *P = dyn_cast<PHINode>(*UI)) { - unsigned OperandNo = UI.getOperandNo(); - UserBB = P->getIncomingBlock(OperandNo/2); - } - - // Check the current block, as a fast-path. Most values are used in the - // same block they are defined in. - if (UserBB != BB && !LoopBBs.count(UserBB)) - return false; - } - } - - return true; -} - -//===-------------------------------------------------------------------===// -// APIs for updating loop information after changing the CFG -// - -/// addBasicBlockToLoop - This function is used by other analyses to update loop -/// information. NewBB is set to be a new member of the current loop. Because -/// of this, it is added as a member of all parent loops, and is added to the -/// specified LoopInfo object as being in the current basic block. It is not -/// valid to replace the loop header with this method. -/// -void Loop::addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI) { - assert((Blocks.empty() || LI[getHeader()] == this) && - "Incorrect LI specified for this loop!"); - assert(NewBB && "Cannot add a null basic block to the loop!"); - assert(LI[NewBB] == 0 && "BasicBlock already in the loop!"); - - // Add the loop mapping to the LoopInfo object... - LI.BBMap[NewBB] = this; - - // Add the basic block to this loop and all parent loops... - Loop *L = this; - while (L) { - L->Blocks.push_back(NewBB); - L = L->getParentLoop(); - } -} - -/// replaceChildLoopWith - This is used when splitting loops up. It replaces -/// the OldChild entry in our children list with NewChild, and updates the -/// parent pointers of the two loops as appropriate. -void Loop::replaceChildLoopWith(Loop *OldChild, Loop *NewChild) { - assert(OldChild->ParentLoop == this && "This loop is already broken!"); - assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); - std::vector<Loop*>::iterator I = std::find(SubLoops.begin(), SubLoops.end(), - OldChild); - assert(I != SubLoops.end() && "OldChild not in loop!"); - *I = NewChild; - OldChild->ParentLoop = 0; - NewChild->ParentLoop = this; -} - -/// addChildLoop - Add the specified loop to be a child of this loop. -/// -void Loop::addChildLoop(Loop *NewChild) { - assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); - NewChild->ParentLoop = this; - SubLoops.push_back(NewChild); -} - -template<typename T> -static void RemoveFromVector(std::vector<T*> &V, T *N) { - typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N); - assert(I != V.end() && "N is not in this list!"); - V.erase(I); -} - -/// removeChildLoop - This removes the specified child from being a subloop of -/// this loop. The loop is not deleted, as it will presumably be inserted -/// into another loop. -Loop *Loop::removeChildLoop(iterator I) { - assert(I != SubLoops.end() && "Cannot remove end iterator!"); - Loop *Child = *I; - assert(Child->ParentLoop == this && "Child is not a child of this loop!"); - SubLoops.erase(SubLoops.begin()+(I-begin())); - Child->ParentLoop = 0; - return Child; -} - - -/// removeBlockFromLoop - This removes the specified basic block from the -/// current loop, updating the Blocks and ExitBlocks lists as appropriate. This -/// does not update the mapping in the LoopInfo class. -void Loop::removeBlockFromLoop(BasicBlock *BB) { - RemoveFromVector(Blocks, BB); -} - // Ensure this file gets linked when LoopInfo.h is used. DEFINING_FILE_FOR(LoopInfo) |