-//===- LoopInfo.cpp - Natural Loop Calculator -------------------------------=//
+//===- LoopInfo.cpp - Natural Loop Calculator -----------------------------===//
+//
+// 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 defines the LoopInfo class that is used to identify natural loops
// and determine the loop depth of various nodes of the CFG. Note that the
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Constants.h"
+#include "llvm/Instructions.h"
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Assembly/Writer.h"
#include "llvm/Support/CFG.h"
-#include "Support/DepthFirstIterator.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include <algorithm>
+#include <ostream>
+using namespace llvm;
-AnalysisID LoopInfo::ID(AnalysisID::create<LoopInfo>(), true);
+char LoopInfo::ID = 0;
+static RegisterPass<LoopInfo>
+X("loops", "Natural Loop Construction", true);
//===----------------------------------------------------------------------===//
// Loop implementation
//
bool Loop::contains(const BasicBlock *BB) const {
- return find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
+ return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
}
-void LoopInfo::releaseMemory() {
- for (std::vector<Loop*>::iterator I = TopLevelLoops.begin(),
- E = TopLevelLoops.end(); I != E; ++I)
- delete *I; // Delete all of the loops...
+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;
+}
- BBMap.clear(); // Reset internal state of analysis
- TopLevelLoops.clear();
+/// 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
//
-bool LoopInfo::runOnFunction(Function *F) {
+bool LoopInfo::runOnFunction(Function &) {
releaseMemory();
- Calculate(getAnalysis<DominatorSet>()); // Update
+ Calculate(getAnalysis<DominatorTree>()); // Update
return false;
}
-void LoopInfo::Calculate(const DominatorSet &DS) {
- BasicBlock *RootNode = DS.getRoot();
+void LoopInfo::releaseMemory() {
+ for (std::vector<Loop*>::iterator I = TopLevelLoops.begin(),
+ E = TopLevelLoops.end(); I != E; ++I)
+ delete *I; // Delete all of the loops...
+
+ BBMap.clear(); // Reset internal state of analysis
+ TopLevelLoops.clear();
+}
+
+void LoopInfo::Calculate(DominatorTree &DT) {
+ BasicBlock *RootNode = DT.getRootNode()->getBlock();
for (df_iterator<BasicBlock*> NI = df_begin(RootNode),
- NE = df_end(RootNode); NI != NE; ++NI)
- if (Loop *L = ConsiderForLoop(*NI, DS))
+ NE = df_end(RootNode); NI != NE; ++NI)
+ if (Loop *L = ConsiderForLoop(*NI, DT))
TopLevelLoops.push_back(L);
-
- for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
- TopLevelLoops[i]->setLoopDepth(1);
}
void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
- AU.addRequired(DominatorSet::ID);
- AU.addProvided(ID);
+ AU.addRequired<DominatorTree>();
}
+void LoopInfo::print(std::ostream &OS, const Module* ) const {
+ for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
+ TopLevelLoops[i]->print(OS);
+#if 0
+ for (std::map<BasicBlock*, Loop*>::const_iterator I = BBMap.begin(),
+ E = BBMap.end(); I != E; ++I)
+ OS << "BB '" << I->first->getName() << "' level = "
+ << I->second->getLoopDepth() << "\n";
+#endif
+}
-Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS) {
- if (BBMap.find(BB) != BBMap.end()) return 0; // Havn't processed this node?
+static bool isNotAlreadyContainedIn(Loop *SubLoop, Loop *ParentLoop) {
+ if (SubLoop == 0) return true;
+ if (SubLoop == ParentLoop) return false;
+ return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
+}
+
+Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, DominatorTree &DT) {
+ if (BBMap.find(BB) != BBMap.end()) return 0; // Haven't processed this node?
std::vector<BasicBlock *> TodoStack;
// Scan the predecessors of BB, checking to see if BB dominates any of
- // them.
+ // them. This identifies backedges which target this node...
for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I)
- if (DS.dominates(BB, *I)) // If BB dominates it's predecessor...
+ if (DT.dominates(BB, *I)) // If BB dominates it's predecessor...
TodoStack.push_back(*I);
- if (TodoStack.empty()) return 0; // Doesn't dominate any predecessors...
+ if (TodoStack.empty()) return 0; // No backedges to this block...
// Create a new loop to represent this basic block...
Loop *L = new Loop(BB);
BBMap[BB] = L;
+ BasicBlock *EntryBlock = &BB->getParent()->getEntryBlock();
+
while (!TodoStack.empty()) { // Process all the nodes in the loop
BasicBlock *X = TodoStack.back();
TodoStack.pop_back();
- if (!L->contains(X)) { // As of yet unprocessed??
+ if (!L->contains(X) && // As of yet unprocessed??
+ DT.dominates(EntryBlock, X)) { // X is reachable from entry block?
+ // Check to see if this block already belongs to a loop. If this occurs
+ // then we have a case where a loop that is supposed to be a child of the
+ // current loop was processed before the current loop. When this occurs,
+ // this child loop gets added to a part of the current loop, making it a
+ // sibling to the current loop. We have to reparent this loop.
+ if (Loop *SubLoop = const_cast<Loop*>(getLoopFor(X)))
+ if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)) {
+ // Remove the subloop from it's current parent...
+ assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L);
+ Loop *SLP = SubLoop->ParentLoop; // SubLoopParent
+ std::vector<Loop*>::iterator I =
+ std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop);
+ assert(I != SLP->SubLoops.end() && "SubLoop not a child of parent?");
+ SLP->SubLoops.erase(I); // Remove from parent...
+
+ // Add the subloop to THIS loop...
+ SubLoop->ParentLoop = L;
+ L->SubLoops.push_back(SubLoop);
+ }
+
+ // Normal case, add the block to our loop...
L->Blocks.push_back(X);
// Add all of the predecessors of X to the end of the work stack...
}
}
+ // If there are any loops nested within this loop, create them now!
+ for (std::vector<BasicBlock*>::iterator I = L->Blocks.begin(),
+ E = L->Blocks.end(); I != E; ++I)
+ if (Loop *NewLoop = ConsiderForLoop(*I, DT)) {
+ L->SubLoops.push_back(NewLoop);
+ NewLoop->ParentLoop = L;
+ }
+
// Add the basic blocks that comprise this loop to the BBMap so that this
- // loop can be found for them. Also check subsidary basic blocks to see if
- // they start subloops of their own.
+ // loop can be found for them.
//
- for (std::vector<BasicBlock*>::reverse_iterator I = L->Blocks.rbegin(),
- E = L->Blocks.rend(); I != E; ++I) {
+ for (std::vector<BasicBlock*>::iterator I = L->Blocks.begin(),
+ E = L->Blocks.end(); I != E; ++I) {
+ std::map<BasicBlock*, Loop*>::iterator BBMI = BBMap.lower_bound(*I);
+ if (BBMI == BBMap.end() || BBMI->first != *I) // Not in map yet...
+ BBMap.insert(BBMI, std::make_pair(*I, L)); // Must be at this level
+ }
- // Check to see if this block starts a new loop
- if (Loop *NewLoop = ConsiderForLoop(*I, DS)) {
- L->SubLoops.push_back(NewLoop);
- NewLoop->ParentLoop = L;
+ // Now that we have a list of all of the child loops of this loop, check to
+ // see if any of them should actually be nested inside of each other. We can
+ // accidentally pull loops our of their parents, so we must make sure to
+ // organize the loop nests correctly now.
+ {
+ std::map<BasicBlock*, Loop*> ContainingLoops;
+ for (unsigned i = 0; i != L->SubLoops.size(); ++i) {
+ Loop *Child = L->SubLoops[i];
+ assert(Child->getParentLoop() == L && "Not proper child loop?");
+
+ if (Loop *ContainingLoop = ContainingLoops[Child->getHeader()]) {
+ // If there is already a loop which contains this loop, move this loop
+ // into the containing loop.
+ MoveSiblingLoopInto(Child, ContainingLoop);
+ --i; // The loop got removed from the SubLoops list.
+ } else {
+ // This is currently considered to be a top-level loop. Check to see if
+ // any of the contained blocks are loop headers for subloops we have
+ // already processed.
+ for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) {
+ Loop *&BlockLoop = ContainingLoops[Child->Blocks[b]];
+ if (BlockLoop == 0) { // Child block not processed yet...
+ BlockLoop = Child;
+ } else if (BlockLoop != Child) {
+ Loop *SubLoop = BlockLoop;
+ // Reparent all of the blocks which used to belong to BlockLoops
+ for (unsigned j = 0, e = SubLoop->Blocks.size(); j != e; ++j)
+ ContainingLoops[SubLoop->Blocks[j]] = Child;
+
+ // There is already a loop which contains this block, that means
+ // that we should reparent the loop which the block is currently
+ // considered to belong to to be a child of this loop.
+ MoveSiblingLoopInto(SubLoop, Child);
+ --i; // We just shrunk the SubLoops list.
+ }
+ }
+ }
}
-
- if (BBMap.find(*I) == BBMap.end())
- BBMap.insert(std::make_pair(*I, L));
}
return L;
}
+
+/// MoveSiblingLoopInto - This method moves the NewChild loop to live inside of
+/// the NewParent Loop, instead of being a sibling of it.
+void LoopInfo::MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent) {
+ Loop *OldParent = NewChild->getParentLoop();
+ assert(OldParent && OldParent == NewParent->getParentLoop() &&
+ NewChild != NewParent && "Not sibling loops!");
+
+ // Remove NewChild from being a child of OldParent
+ std::vector<Loop*>::iterator I =
+ std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(), NewChild);
+ assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??");
+ OldParent->SubLoops.erase(I); // Remove from parent's subloops list
+ NewChild->ParentLoop = 0;
+
+ InsertLoopInto(NewChild, NewParent);
+}
+
+/// InsertLoopInto - This inserts loop L into the specified parent loop. If the
+/// parent loop contains a loop which should contain L, the loop gets inserted
+/// into L instead.
+void LoopInfo::InsertLoopInto(Loop *L, Loop *Parent) {
+ BasicBlock *LHeader = L->getHeader();
+ assert(Parent->contains(LHeader) && "This loop should not be inserted here!");
+
+ // Check to see if it belongs in a child loop...
+ for (unsigned i = 0, e = Parent->SubLoops.size(); i != e; ++i)
+ if (Parent->SubLoops[i]->contains(LHeader)) {
+ InsertLoopInto(L, Parent->SubLoops[i]);
+ return;
+ }
+
+ // If not, insert it here!
+ Parent->SubLoops.push_back(L);
+ L->ParentLoop = Parent;
+}
+
+/// changeLoopFor - Change the top-level loop that contains BB to the
+/// specified loop. This should be used by transformations that restructure
+/// the loop hierarchy tree.
+void LoopInfo::changeLoopFor(BasicBlock *BB, Loop *L) {
+ Loop *&OldLoop = BBMap[BB];
+ assert(OldLoop && "Block not in a loop yet!");
+ OldLoop = L;
+}
+
+/// changeTopLevelLoop - Replace the specified loop in the top-level loops
+/// list with the indicated loop.
+void LoopInfo::changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
+ std::vector<Loop*>::iterator I = std::find(TopLevelLoops.begin(),
+ TopLevelLoops.end(), OldLoop);
+ assert(I != TopLevelLoops.end() && "Old loop not at top level!");
+ *I = NewLoop;
+ assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 &&
+ "Loops already embedded into a subloop!");
+}
+
+/// removeLoop - This removes the specified top-level loop from this loop info
+/// object. The loop is not deleted, as it will presumably be inserted into
+/// another loop.
+Loop *LoopInfo::removeLoop(iterator I) {
+ assert(I != end() && "Cannot remove end iterator!");
+ Loop *L = *I;
+ assert(L->getParentLoop() == 0 && "Not a top-level loop!");
+ TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
+ return L;
+}
+
+/// removeBlock - This method completely removes BB from all data structures,
+/// including all of the Loop objects it is nested in and our mapping from
+/// BasicBlocks to loops.
+void LoopInfo::removeBlock(BasicBlock *BB) {
+ std::map<BasicBlock *, Loop*>::iterator I = BBMap.find(BB);
+ if (I != BBMap.end()) {
+ for (Loop *L = I->second; L; L = L->getParentLoop())
+ L->removeBlockFromLoop(BB);
+
+ BBMap.erase(I);
+ }
+}
+
+
+//===----------------------------------------------------------------------===//
+// 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)
projects / oota-llvm.git / blobdiff