From c9b1e25493b393013b28e5d457f2fb2845a4dd9f Mon Sep 17 00:00:00 2001 From: Andrew Trick Date: Tue, 26 Jun 2012 04:11:38 +0000 Subject: Enable the new LoopInfo algorithm by default. The primary advantage is that loop optimizations will be applied in a stable order. This helps debugging and unit test creation. It is also a better overall implementation without pathologically bad performance on deep functions. On large functions (llvm-stress --size=200000 | opt -loops) Before: 0.1263s After: 0.0225s On deep functions (after tweaking llvm-stress, thanks Nadav): Before: 0.2281s After: 0.0227s See r158790 for more comments. The loop tree is now consistently generated in forward order, but loop passes are applied in reverse order over the program. If we have a loop optimization that prefers forward order, that can easily be achieved by adding a different type of LoopPassManager. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159183 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/LoopInfo.h | 24 +++-- include/llvm/Analysis/LoopInfoImpl.h | 179 ----------------------------------- 2 files changed, 11 insertions(+), 192 deletions(-) (limited to 'include/llvm') diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h index 14d87e0..eeb482d 100644 --- a/include/llvm/Analysis/LoopInfo.h +++ b/include/llvm/Analysis/LoopInfo.h @@ -127,8 +127,12 @@ public: const std::vector &getSubLoops() const { return SubLoops; } std::vector &getSubLoopsVector() { return SubLoops; } typedef typename std::vector::const_iterator iterator; + typedef typename std::vector::const_reverse_iterator + reverse_iterator; iterator begin() const { return SubLoops.begin(); } iterator end() const { return SubLoops.end(); } + reverse_iterator rbegin() const { return SubLoops.rbegin(); } + reverse_iterator rend() const { return SubLoops.rend(); } bool empty() const { return SubLoops.empty(); } /// getBlocks - Get a list of the basic blocks which make up this loop. @@ -431,8 +435,12 @@ public: /// function. /// typedef typename std::vector::const_iterator iterator; + typedef typename std::vector::const_reverse_iterator + reverse_iterator; iterator begin() const { return TopLevelLoops.begin(); } iterator end() const { return TopLevelLoops.end(); } + reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); } + reverse_iterator rend() const { return TopLevelLoops.rend(); } bool empty() const { return TopLevelLoops.empty(); } /// getLoopFor - Return the inner most loop that BB lives in. If a basic @@ -525,19 +533,6 @@ public: return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop); } - void Calculate(DominatorTreeBase &DT); - - LoopT *ConsiderForLoop(BlockT *BB, DominatorTreeBase &DT); - - /// MoveSiblingLoopInto - This method moves the NewChild loop to live inside - /// of the NewParent Loop, instead of being a sibling of it. - void MoveSiblingLoopInto(LoopT *NewChild, LoopT *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 InsertLoopInto(LoopT *L, LoopT *Parent); - /// Create the loop forest using a stable algorithm. void Analyze(DominatorTreeBase &DomTree); @@ -570,8 +565,11 @@ public: /// function. /// typedef LoopInfoBase::iterator iterator; + typedef LoopInfoBase::reverse_iterator reverse_iterator; inline iterator begin() const { return LI.begin(); } inline iterator end() const { return LI.end(); } + inline reverse_iterator rbegin() const { return LI.rbegin(); } + inline reverse_iterator rend() const { return LI.rend(); } bool empty() const { return LI.empty(); } /// getLoopFor - Return the inner most loop that BB lives in. If a basic diff --git a/include/llvm/Analysis/LoopInfoImpl.h b/include/llvm/Analysis/LoopInfoImpl.h index 1be717c..c07fbf7 100644 --- a/include/llvm/Analysis/LoopInfoImpl.h +++ b/include/llvm/Analysis/LoopInfoImpl.h @@ -354,185 +354,6 @@ void LoopBase::print(raw_ostream &OS, unsigned Depth) const { } //===----------------------------------------------------------------------===// -/// LoopInfo - This class builds and contains all of the top level loop -/// structures in the specified function. -/// - -template -void LoopInfoBase::Calculate(DominatorTreeBase &DT) { - BlockT *RootNode = DT.getRootNode()->getBlock(); - - for (df_iterator NI = df_begin(RootNode), - NE = df_end(RootNode); NI != NE; ++NI) - if (LoopT *L = ConsiderForLoop(*NI, DT)) - TopLevelLoops.push_back(L); -} - -template -LoopT *LoopInfoBase:: -ConsiderForLoop(BlockT *BB, DominatorTreeBase &DT) { - if (BBMap.count(BB)) return 0; // Haven't processed this node? - - std::vector TodoStack; - - // Scan the predecessors of BB, checking to see if BB dominates any of - // them. This identifies backedges which target this node... - typedef GraphTraits > InvBlockTraits; - for (typename InvBlockTraits::ChildIteratorType I = - InvBlockTraits::child_begin(BB), E = InvBlockTraits::child_end(BB); - I != E; ++I) { - typename InvBlockTraits::NodeType *N = *I; - // If BB dominates its predecessor... - if (DT.dominates(BB, N) && DT.isReachableFromEntry(N)) - TodoStack.push_back(N); - } - - if (TodoStack.empty()) return 0; // No backedges to this block... - - // Create a new loop to represent this basic block... - LoopT *L = new LoopT(BB); - BBMap[BB] = L; - - while (!TodoStack.empty()) { // Process all the nodes in the loop - BlockT *X = TodoStack.back(); - TodoStack.pop_back(); - - if (!L->contains(X) && // As of yet unprocessed?? - DT.isReachableFromEntry(X)) { - // 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 (LoopT *SubLoop = - const_cast(getLoopFor(X))) - if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)){ - // Remove the subloop from its current parent... - assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L); - LoopT *SLP = SubLoop->ParentLoop; // SubLoopParent - typename 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); - - typedef GraphTraits > InvBlockTraits; - - // Add all of the predecessors of X to the end of the work stack... - TodoStack.insert(TodoStack.end(), InvBlockTraits::child_begin(X), - InvBlockTraits::child_end(X)); - } - } - - // If there are any loops nested within this loop, create them now! - for (typename std::vector::iterator I = L->Blocks.begin(), - E = L->Blocks.end(); I != E; ++I) - if (LoopT *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. - // - for (typename std::vector::iterator I = L->Blocks.begin(), - E = L->Blocks.end(); I != E; ++I) - BBMap.insert(std::make_pair(*I, 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 ContainingLoops; - for (unsigned i = 0; i != L->SubLoops.size(); ++i) { - LoopT *Child = L->SubLoops[i]; - assert(Child->getParentLoop() == L && "Not proper child loop?"); - - if (LoopT *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) { - LoopT *&BlockLoop = ContainingLoops[Child->Blocks[b]]; - if (BlockLoop == 0) { // Child block not processed yet... - BlockLoop = Child; - } else if (BlockLoop != Child) { - LoopT *SubLoop = BlockLoop; - // Reparent all of the blocks which used to belong to BlockLoops - for (unsigned j = 0, f = SubLoop->Blocks.size(); j != f; ++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. - } - } - } - } - } - - return L; -} - -/// MoveSiblingLoopInto - This method moves the NewChild loop to live inside -/// of the NewParent Loop, instead of being a sibling of it. -template -void LoopInfoBase:: -MoveSiblingLoopInto(LoopT *NewChild, LoopT *NewParent) { - LoopT *OldParent = NewChild->getParentLoop(); - assert(OldParent && OldParent == NewParent->getParentLoop() && - NewChild != NewParent && "Not sibling loops!"); - - // Remove NewChild from being a child of OldParent - typename std::vector::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. -template -void LoopInfoBase::InsertLoopInto(LoopT *L, LoopT *Parent) { - BlockT *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 = static_cast(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; -} - -//===----------------------------------------------------------------------===// /// Stable LoopInfo Analysis - Build a loop tree using stable iterators so the /// result does / not depend on use list (block predecessor) order. /// -- cgit v1.1