X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FLoopInfo.cpp;h=7a1daa089e28361ebe3cc7ada275b876f6a64d5a;hb=c53544af06acf3fba1788613a364f1f40317869e;hp=ef4b6430ba2ad4aa1b0c511569c00e25b1cb18fa;hpb=ae5d39e1bba338e41911d5e002c96c88d7618db8;p=oota-llvm.git diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp index ef4b6430ba2..7a1daa089e2 100644 --- a/lib/Analysis/LoopInfo.cpp +++ b/lib/Analysis/LoopInfo.cpp @@ -27,24 +27,24 @@ bool Loop::contains(const BasicBlock *BB) const { bool Loop::isLoopExit(const BasicBlock *BB) const { for (BasicBlock::succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI) { - if (! contains(*SI)) + if (!contains(*SI)) return true; } return false; } unsigned Loop::getNumBackEdges() const { - unsigned numBackEdges = 0; - BasicBlock *header = Blocks.front(); + unsigned NumBackEdges = 0; + BasicBlock *H = getHeader(); for (std::vector::const_iterator I = Blocks.begin(), - E = Blocks.end(); I != E; ++I) { + E = Blocks.end(); I != E; ++I) for (BasicBlock::succ_iterator SI = succ_begin(*I), SE = succ_end(*I); SI != SE; ++SI) - if (header == *SI) - ++numBackEdges; - } - return numBackEdges; + if (*SI == H) + ++NumBackEdges; + + return NumBackEdges; } void Loop::print(std::ostream &OS) const { @@ -52,14 +52,27 @@ void Loop::print(std::ostream &OS) const { for (unsigned i = 0; i < getBlocks().size(); ++i) { if (i) OS << ","; - WriteAsOperand(OS, (const Value*)getBlocks()[i]); + WriteAsOperand(OS, getBlocks()[i], false); + } + if (!ExitBlocks.empty()) { + OS << "\tExitBlocks: "; + for (unsigned i = 0; i < getExitBlocks().size(); ++i) { + if (i) OS << ","; + WriteAsOperand(OS, getExitBlocks()[i], false); + } } + OS << "\n"; for (unsigned i = 0, e = getSubLoops().size(); i != e; ++i) getSubLoops()[i]->print(OS); } +void Loop::dump() const { + print(std::cerr); +} + + //===----------------------------------------------------------------------===// // LoopInfo implementation // @@ -101,6 +114,12 @@ void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const { void LoopInfo::print(std::ostream &OS) const { for (unsigned i = 0; i < TopLevelLoops.size(); ++i) TopLevelLoops[i]->print(OS); +#if 0 + for (std::map::const_iterator I = BBMap.begin(), + E = BBMap.end(); I != E; ++I) + OS << "BB '" << I->first->getName() << "' level = " + << I->second->LoopDepth << "\n"; +#endif } Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS) { @@ -109,12 +128,12 @@ Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS) { std::vector 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... 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); @@ -124,51 +143,61 @@ Loop *LoopInfo::ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS) { BasicBlock *X = TodoStack.back(); TodoStack.pop_back(); - if (!L->contains(X)) { // As of yet unprocessed?? - L->Blocks.push_back(X); + if (!L->contains(X)) { // As of yet unprocessed?? + // 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(getLoopFor(X))) + if (SubLoop->getHeader() == X && X != BB) { + // Remove the subloop from it's current parent... + assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L); + Loop *SLP = SubLoop->ParentLoop; // SubLoopParent + std::vector::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... TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X)); } } + // If there are any loops nested within this loop, create them now! + for (std::vector::iterator I = L->Blocks.begin(), + E = L->Blocks.end(); I != E; ++I) + if (Loop *NewLoop = ConsiderForLoop(*I, DS)) { + 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::reverse_iterator I = L->Blocks.rbegin(), - E = L->Blocks.rend(); I != E; ++I) - - // Check to see if this block starts a new loop - if (*I != BB) - if (Loop *NewLoop = ConsiderForLoop(*I, DS)) { - L->SubLoops.push_back(NewLoop); - NewLoop->ParentLoop = L; - } else { - std::map::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)); - } else { - // If this is already in the BBMap then this means that we already - // added a loop for it, but incorrectly added the loop to a higher - // level loop instead of the current loop we are creating. Fix this - // now by moving the loop into the correct subloop. - // - Loop *SubLoop = BBMI->second; - Loop *OldSubLoopParent = SubLoop->getParentLoop(); - if (OldSubLoopParent != L) { - // Remove SubLoop from OldSubLoopParent's list of subloops... - std::vector::iterator I = - std::find(OldSubLoopParent->SubLoops.begin(), - OldSubLoopParent->SubLoops.end(), SubLoop); - assert(I != OldSubLoopParent->SubLoops.end() - && "Loop parent doesn't contain loop?"); - OldSubLoopParent->SubLoops.erase(I); - SubLoop->ParentLoop = L; - L->SubLoops.push_back(SubLoop); - } - } - } + for (std::vector::iterator I = L->Blocks.begin(), + E = L->Blocks.end(); I != E; ++I) { + std::map::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 + } + + // Now that we know all of the blocks that make up this loop, see if there are + // any branches to outside of the loop... building the ExitBlocks list. + for (std::vector::iterator BI = L->Blocks.begin(), + BE = L->Blocks.end(); BI != BE; ++BI) + for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) + if (!L->contains(*I)) // Not in current loop? + L->ExitBlocks.push_back(*I); // It must be an exit block... return L; } @@ -196,6 +225,13 @@ BasicBlock *Loop::getLoopPreheader() const { return 0; // Multiple predecessors outside the loop Out = *PI; } + + // Make sure there is only one exit out of the preheader... + 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. @@ -223,3 +259,19 @@ void Loop::addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI) { L = L->getParentLoop(); } } + +/// changeExitBlock - This method is used to update loop information. All +/// instances of the specified Old basic block are removed from the exit list +/// and replaced with New. +/// +void Loop::changeExitBlock(BasicBlock *Old, BasicBlock *New) { + assert(Old != New && "Cannot changeExitBlock to the same thing!"); + assert(Old && New && "Cannot changeExitBlock to or from a null node!"); + assert(hasExitBlock(Old) && "Old exit block not found!"); + std::vector::iterator + I = std::find(ExitBlocks.begin(), ExitBlocks.end(), Old); + while (I != ExitBlocks.end()) { + *I = New; + I = std::find(I+1, ExitBlocks.end(), Old); + } +}