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isLCSSAForm(), to test whether a loop is in the form guaranteed by the LoopSimplify pass. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76077 91177308-0d34-0410-b5e6-96231b3b80d8
1023 lines
38 KiB
C++
1023 lines
38 KiB
C++
//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the LoopInfo class that is used to identify natural loops
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// and determine the loop depth of various nodes of the CFG. Note that natural
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// loops may actually be several loops that share the same header node.
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//
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// This analysis calculates the nesting structure of loops in a function. For
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// each natural loop identified, this analysis identifies natural loops
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// contained entirely within the loop and the basic blocks the make up the loop.
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//
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// It can calculate on the fly various bits of information, for example:
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//
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// * whether there is a preheader for the loop
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// * the number of back edges to the header
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// * whether or not a particular block branches out of the loop
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// * the successor blocks of the loop
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// * the loop depth
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// * the trip count
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// * etc...
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_LOOP_INFO_H
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#define LLVM_ANALYSIS_LOOP_INFO_H
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#include "llvm/Pass.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Support/Streams.h"
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#include <algorithm>
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#include <ostream>
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namespace llvm {
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template<typename T>
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static void RemoveFromVector(std::vector<T*> &V, T *N) {
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typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
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assert(I != V.end() && "N is not in this list!");
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V.erase(I);
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}
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class DominatorTree;
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class LoopInfo;
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class Loop;
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template<class N, class M> class LoopInfoBase;
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template<class N, class M> class LoopBase;
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//===----------------------------------------------------------------------===//
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/// LoopBase class - Instances of this class are used to represent loops that
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/// are detected in the flow graph
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///
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template<class BlockT, class LoopT>
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class LoopBase {
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LoopT *ParentLoop;
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// SubLoops - Loops contained entirely within this one.
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std::vector<LoopT *> SubLoops;
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// Blocks - The list of blocks in this loop. First entry is the header node.
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std::vector<BlockT*> Blocks;
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// DO NOT IMPLEMENT
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LoopBase(const LoopBase<BlockT, LoopT> &);
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// DO NOT IMPLEMENT
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const LoopBase<BlockT, LoopT>&operator=(const LoopBase<BlockT, LoopT> &);
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public:
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/// Loop ctor - This creates an empty loop.
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LoopBase() : ParentLoop(0) {}
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~LoopBase() {
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for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
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delete SubLoops[i];
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}
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/// getLoopDepth - Return the nesting level of this loop. An outer-most
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/// loop has depth 1, for consistency with loop depth values used for basic
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/// blocks, where depth 0 is used for blocks not inside any loops.
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unsigned getLoopDepth() const {
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unsigned D = 1;
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for (const LoopT *CurLoop = ParentLoop; CurLoop;
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CurLoop = CurLoop->ParentLoop)
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++D;
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return D;
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}
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BlockT *getHeader() const { return Blocks.front(); }
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LoopT *getParentLoop() const { return ParentLoop; }
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/// contains - Return true if the specified basic block is in this loop
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///
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bool contains(const BlockT *BB) const {
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return std::find(block_begin(), block_end(), BB) != block_end();
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}
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/// iterator/begin/end - Return the loops contained entirely within this loop.
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///
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const std::vector<LoopT *> &getSubLoops() const { return SubLoops; }
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typedef typename std::vector<LoopT *>::const_iterator iterator;
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iterator begin() const { return SubLoops.begin(); }
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iterator end() const { return SubLoops.end(); }
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bool empty() const { return SubLoops.empty(); }
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/// getBlocks - Get a list of the basic blocks which make up this loop.
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///
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const std::vector<BlockT*> &getBlocks() const { return Blocks; }
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typedef typename std::vector<BlockT*>::const_iterator block_iterator;
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block_iterator block_begin() const { return Blocks.begin(); }
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block_iterator block_end() const { return Blocks.end(); }
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/// isLoopExit - True if terminator in the block can branch to another block
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/// that is outside of the current loop.
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///
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bool isLoopExit(const BlockT *BB) const {
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typedef GraphTraits<BlockT*> BlockTraits;
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for (typename BlockTraits::ChildIteratorType SI =
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BlockTraits::child_begin(const_cast<BlockT*>(BB)),
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SE = BlockTraits::child_end(const_cast<BlockT*>(BB)); SI != SE; ++SI) {
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if (!contains(*SI))
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return true;
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}
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return false;
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}
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/// getNumBackEdges - Calculate the number of back edges to the loop header
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///
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unsigned getNumBackEdges() const {
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unsigned NumBackEdges = 0;
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BlockT *H = getHeader();
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typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
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for (typename InvBlockTraits::ChildIteratorType I =
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InvBlockTraits::child_begin(const_cast<BlockT*>(H)),
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E = InvBlockTraits::child_end(const_cast<BlockT*>(H)); I != E; ++I)
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if (contains(*I))
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++NumBackEdges;
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return NumBackEdges;
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}
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//===--------------------------------------------------------------------===//
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// APIs for simple analysis of the loop.
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//
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// Note that all of these methods can fail on general loops (ie, there may not
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// be a preheader, etc). For best success, the loop simplification and
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// induction variable canonicalization pass should be used to normalize loops
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// for easy analysis. These methods assume canonical loops.
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/// getExitingBlocks - Return all blocks inside the loop that have successors
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/// outside of the loop. These are the blocks _inside of the current loop_
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/// which branch out. The returned list is always unique.
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///
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void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const {
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// Sort the blocks vector so that we can use binary search to do quick
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// lookups.
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SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
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std::sort(LoopBBs.begin(), LoopBBs.end());
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typedef GraphTraits<BlockT*> BlockTraits;
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for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
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for (typename BlockTraits::ChildIteratorType I =
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BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
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I != E; ++I)
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if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) {
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// Not in current loop? It must be an exit block.
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ExitingBlocks.push_back(*BI);
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break;
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}
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}
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/// getExitingBlock - If getExitingBlocks would return exactly one block,
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/// return that block. Otherwise return null.
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BlockT *getExitingBlock() const {
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SmallVector<BlockT*, 8> ExitingBlocks;
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getExitingBlocks(ExitingBlocks);
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if (ExitingBlocks.size() == 1)
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return ExitingBlocks[0];
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return 0;
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}
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/// getExitBlocks - Return all of the successor blocks of this loop. These
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/// are the blocks _outside of the current loop_ which are branched to.
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///
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void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
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// Sort the blocks vector so that we can use binary search to do quick
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// lookups.
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SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
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std::sort(LoopBBs.begin(), LoopBBs.end());
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typedef GraphTraits<BlockT*> BlockTraits;
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for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
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for (typename BlockTraits::ChildIteratorType I =
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BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
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I != E; ++I)
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if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
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// Not in current loop? It must be an exit block.
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ExitBlocks.push_back(*I);
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}
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/// getExitBlock - If getExitBlocks would return exactly one block,
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/// return that block. Otherwise return null.
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BlockT *getExitBlock() const {
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SmallVector<BlockT*, 8> ExitBlocks;
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getExitBlocks(ExitBlocks);
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if (ExitBlocks.size() == 1)
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return ExitBlocks[0];
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return 0;
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}
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/// getUniqueExitBlocks - Return all unique successor blocks of this loop.
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/// These are the blocks _outside of the current loop_ which are branched to.
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/// This assumes that loop is in canonical form.
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///
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void getUniqueExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
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// Sort the blocks vector so that we can use binary search to do quick
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// lookups.
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SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
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std::sort(LoopBBs.begin(), LoopBBs.end());
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std::vector<BlockT*> switchExitBlocks;
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for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) {
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BlockT *current = *BI;
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switchExitBlocks.clear();
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typedef GraphTraits<BlockT*> BlockTraits;
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typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
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for (typename BlockTraits::ChildIteratorType I =
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BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI);
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I != E; ++I) {
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if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
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// If block is inside the loop then it is not a exit block.
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continue;
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typename InvBlockTraits::ChildIteratorType PI =
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InvBlockTraits::child_begin(*I);
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BlockT *firstPred = *PI;
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// If current basic block is this exit block's first predecessor
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// then only insert exit block in to the output ExitBlocks vector.
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// This ensures that same exit block is not inserted twice into
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// ExitBlocks vector.
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if (current != firstPred)
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continue;
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// If a terminator has more then two successors, for example SwitchInst,
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// then it is possible that there are multiple edges from current block
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// to one exit block.
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if (std::distance(BlockTraits::child_begin(current),
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BlockTraits::child_end(current)) <= 2) {
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ExitBlocks.push_back(*I);
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continue;
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}
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// In case of multiple edges from current block to exit block, collect
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// only one edge in ExitBlocks. Use switchExitBlocks to keep track of
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// duplicate edges.
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if (std::find(switchExitBlocks.begin(), switchExitBlocks.end(), *I)
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== switchExitBlocks.end()) {
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switchExitBlocks.push_back(*I);
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ExitBlocks.push_back(*I);
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}
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}
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}
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}
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/// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
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/// block, return that block. Otherwise return null.
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BlockT *getUniqueExitBlock() const {
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SmallVector<BlockT*, 8> UniqueExitBlocks;
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getUniqueExitBlocks(UniqueExitBlocks);
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if (UniqueExitBlocks.size() == 1)
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return UniqueExitBlocks[0];
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return 0;
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}
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/// getLoopPreheader - If there is a preheader for this loop, return it. A
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/// loop has a preheader if there is only one edge to the header of the loop
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/// from outside of the loop. If this is the case, the block branching to the
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/// header of the loop is the preheader node.
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///
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/// This method returns null if there is no preheader for the loop.
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///
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BlockT *getLoopPreheader() const {
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// Keep track of nodes outside the loop branching to the header...
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BlockT *Out = 0;
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// Loop over the predecessors of the header node...
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BlockT *Header = getHeader();
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typedef GraphTraits<BlockT*> BlockTraits;
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typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
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for (typename InvBlockTraits::ChildIteratorType PI =
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InvBlockTraits::child_begin(Header),
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PE = InvBlockTraits::child_end(Header); PI != PE; ++PI)
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if (!contains(*PI)) { // If the block is not in the loop...
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if (Out && Out != *PI)
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return 0; // Multiple predecessors outside the loop
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Out = *PI;
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}
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// Make sure there is only one exit out of the preheader.
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assert(Out && "Header of loop has no predecessors from outside loop?");
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typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out);
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++SI;
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if (SI != BlockTraits::child_end(Out))
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return 0; // Multiple exits from the block, must not be a preheader.
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// If there is exactly one preheader, return it. If there was zero, then
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// Out is still null.
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return Out;
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}
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/// getLoopLatch - If there is a single latch block for this loop, return it.
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/// A latch block is a block that contains a branch back to the header.
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/// A loop header in normal form has two edges into it: one from a preheader
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/// and one from a latch block.
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BlockT *getLoopLatch() const {
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BlockT *Header = getHeader();
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typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
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typename InvBlockTraits::ChildIteratorType PI =
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InvBlockTraits::child_begin(Header);
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typename InvBlockTraits::ChildIteratorType PE =
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InvBlockTraits::child_end(Header);
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if (PI == PE) return 0; // no preds?
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BlockT *Latch = 0;
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if (contains(*PI))
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Latch = *PI;
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++PI;
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if (PI == PE) return 0; // only one pred?
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if (contains(*PI)) {
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if (Latch) return 0; // multiple backedges
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Latch = *PI;
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}
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++PI;
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if (PI != PE) return 0; // more than two preds
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return Latch;
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}
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//===--------------------------------------------------------------------===//
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// APIs for updating loop information after changing the CFG
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//
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/// addBasicBlockToLoop - This method is used by other analyses to update loop
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/// information. NewBB is set to be a new member of the current loop.
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/// Because of this, it is added as a member of all parent loops, and is added
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/// to the specified LoopInfo object as being in the current basic block. It
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/// is not valid to replace the loop header with this method.
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///
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void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
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/// replaceChildLoopWith - This is used when splitting loops up. It replaces
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/// the OldChild entry in our children list with NewChild, and updates the
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/// parent pointer of OldChild to be null and the NewChild to be this loop.
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/// This updates the loop depth of the new child.
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void replaceChildLoopWith(LoopT *OldChild,
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LoopT *NewChild) {
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assert(OldChild->ParentLoop == this && "This loop is already broken!");
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assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
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typename std::vector<LoopT *>::iterator I =
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std::find(SubLoops.begin(), SubLoops.end(), OldChild);
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assert(I != SubLoops.end() && "OldChild not in loop!");
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*I = NewChild;
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OldChild->ParentLoop = 0;
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NewChild->ParentLoop = static_cast<LoopT *>(this);
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}
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/// addChildLoop - Add the specified loop to be a child of this loop. This
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/// updates the loop depth of the new child.
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///
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void addChildLoop(LoopT *NewChild) {
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assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
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NewChild->ParentLoop = static_cast<LoopT *>(this);
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SubLoops.push_back(NewChild);
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}
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/// removeChildLoop - This removes the specified child from being a subloop of
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/// this loop. The loop is not deleted, as it will presumably be inserted
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/// into another loop.
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LoopT *removeChildLoop(iterator I) {
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assert(I != SubLoops.end() && "Cannot remove end iterator!");
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LoopT *Child = *I;
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assert(Child->ParentLoop == this && "Child is not a child of this loop!");
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SubLoops.erase(SubLoops.begin()+(I-begin()));
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Child->ParentLoop = 0;
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return Child;
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}
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/// addBlockEntry - This adds a basic block directly to the basic block list.
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/// This should only be used by transformations that create new loops. Other
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/// transformations should use addBasicBlockToLoop.
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void addBlockEntry(BlockT *BB) {
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Blocks.push_back(BB);
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}
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/// moveToHeader - This method is used to move BB (which must be part of this
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/// loop) to be the loop header of the loop (the block that dominates all
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/// others).
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void moveToHeader(BlockT *BB) {
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if (Blocks[0] == BB) return;
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for (unsigned i = 0; ; ++i) {
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assert(i != Blocks.size() && "Loop does not contain BB!");
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if (Blocks[i] == BB) {
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Blocks[i] = Blocks[0];
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Blocks[0] = BB;
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return;
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}
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}
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}
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/// removeBlockFromLoop - This removes the specified basic block from the
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/// current loop, updating the Blocks as appropriate. This does not update
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/// the mapping in the LoopInfo class.
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void removeBlockFromLoop(BlockT *BB) {
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RemoveFromVector(Blocks, BB);
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}
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/// verifyLoop - Verify loop structure
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void verifyLoop() const {
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#ifndef NDEBUG
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assert (getHeader() && "Loop header is missing");
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assert (getLoopPreheader() && "Loop preheader is missing");
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assert (getLoopLatch() && "Loop latch is missing");
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for (iterator I = SubLoops.begin(), E = SubLoops.end(); I != E; ++I)
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(*I)->verifyLoop();
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#endif
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}
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void print(std::ostream &OS, unsigned Depth = 0) const {
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OS << std::string(Depth*2, ' ') << "Loop at depth " << getLoopDepth()
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<< " containing: ";
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for (unsigned i = 0; i < getBlocks().size(); ++i) {
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if (i) OS << ",";
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BlockT *BB = getBlocks()[i];
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WriteAsOperand(OS, BB, false);
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if (BB == getHeader()) OS << "<header>";
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if (BB == getLoopLatch()) OS << "<latch>";
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if (isLoopExit(BB)) OS << "<exit>";
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}
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OS << "\n";
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for (iterator I = begin(), E = end(); I != E; ++I)
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(*I)->print(OS, Depth+2);
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}
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void print(std::ostream *O, unsigned Depth = 0) const {
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if (O) print(*O, Depth);
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}
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void dump() const {
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print(cerr);
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}
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protected:
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friend class LoopInfoBase<BlockT, LoopT>;
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explicit LoopBase(BlockT *BB) : ParentLoop(0) {
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Blocks.push_back(BB);
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}
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};
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class Loop : public LoopBase<BasicBlock, Loop> {
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public:
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Loop() {}
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/// isLoopInvariant - Return true if the specified value is loop invariant
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///
|
|
bool isLoopInvariant(Value *V) const;
|
|
|
|
/// isLoopInvariant - Return true if the specified instruction is
|
|
/// loop-invariant.
|
|
///
|
|
bool isLoopInvariant(Instruction *I) const;
|
|
|
|
/// makeLoopInvariant - If the given value is an instruction inside of the
|
|
/// loop and it can be hoisted, do so to make it trivially loop-invariant.
|
|
/// Return true if the value after any hoisting is loop invariant. This
|
|
/// function can be used as a slightly more aggressive replacement for
|
|
/// isLoopInvariant.
|
|
///
|
|
/// If InsertPt is specified, it is the point to hoist instructions to.
|
|
/// If null, the terminator of the loop preheader is used.
|
|
///
|
|
bool makeLoopInvariant(Value *V, bool &Changed,
|
|
Instruction *InsertPt = 0) const;
|
|
|
|
/// makeLoopInvariant - If the given instruction is inside of the
|
|
/// loop and it can be hoisted, do so to make it trivially loop-invariant.
|
|
/// Return true if the instruction after any hoisting is loop invariant. This
|
|
/// function can be used as a slightly more aggressive replacement for
|
|
/// isLoopInvariant.
|
|
///
|
|
/// If InsertPt is specified, it is the point to hoist instructions to.
|
|
/// If null, the terminator of the loop preheader is used.
|
|
///
|
|
bool makeLoopInvariant(Instruction *I, bool &Changed,
|
|
Instruction *InsertPt = 0) const;
|
|
|
|
/// 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.
|
|
///
|
|
/// The IndVarSimplify pass transforms loops to have a canonical induction
|
|
/// variable.
|
|
///
|
|
PHINode *getCanonicalInductionVariable() const;
|
|
|
|
/// 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 *getCanonicalInductionVariableIncrement() const;
|
|
|
|
/// 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.
|
|
///
|
|
/// The IndVarSimplify pass transforms loops to have a form that this
|
|
/// function easily understands.
|
|
///
|
|
Value *getTripCount() const;
|
|
|
|
/// getSmallConstantTripCount - Returns the trip count of this loop as a
|
|
/// normal unsigned value, if possible. Returns 0 if the trip count is unknown
|
|
/// of not constant. Will also return 0 if the trip count is very large
|
|
/// (>= 2^32)
|
|
unsigned getSmallConstantTripCount() const;
|
|
|
|
/// getSmallConstantTripMultiple - Returns the largest constant divisor of the
|
|
/// trip count of this loop as a normal unsigned value, if possible. This
|
|
/// means that the actual trip count is always a multiple of the returned
|
|
/// value (don't forget the trip count could very well be zero as well!).
|
|
///
|
|
/// Returns 1 if the trip count is unknown or not guaranteed to be the
|
|
/// multiple of a constant (which is also the case if the trip count is simply
|
|
/// constant, use getSmallConstantTripCount for that case), Will also return 1
|
|
/// if the trip count is very large (>= 2^32).
|
|
unsigned getSmallConstantTripMultiple() const;
|
|
|
|
/// isLCSSAForm - Return true if the Loop is in LCSSA form
|
|
bool isLCSSAForm() const;
|
|
|
|
/// isLoopSimplifyForm - Return true if the Loop is in the form that
|
|
/// the LoopSimplify form transforms loops to, which is sometimes called
|
|
/// normal form.
|
|
bool isLoopSimplifyForm() const;
|
|
|
|
private:
|
|
friend class LoopInfoBase<BasicBlock, Loop>;
|
|
explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
|
|
};
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
/// LoopInfo - This class builds and contains all of the top level loop
|
|
/// structures in the specified function.
|
|
///
|
|
|
|
template<class BlockT, class LoopT>
|
|
class LoopInfoBase {
|
|
// BBMap - Mapping of basic blocks to the inner most loop they occur in
|
|
std::map<BlockT *, LoopT *> BBMap;
|
|
std::vector<LoopT *> TopLevelLoops;
|
|
friend class LoopBase<BlockT, LoopT>;
|
|
|
|
void operator=(const LoopInfoBase &); // do not implement
|
|
LoopInfoBase(const LoopInfo &); // do not implement
|
|
public:
|
|
LoopInfoBase() { }
|
|
~LoopInfoBase() { releaseMemory(); }
|
|
|
|
void releaseMemory() {
|
|
for (typename std::vector<LoopT *>::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();
|
|
}
|
|
|
|
/// iterator/begin/end - The interface to the top-level loops in the current
|
|
/// function.
|
|
///
|
|
typedef typename std::vector<LoopT *>::const_iterator iterator;
|
|
iterator begin() const { return TopLevelLoops.begin(); }
|
|
iterator end() const { return TopLevelLoops.end(); }
|
|
bool empty() const { return TopLevelLoops.empty(); }
|
|
|
|
/// getLoopFor - Return the inner most loop that BB lives in. If a basic
|
|
/// block is in no loop (for example the entry node), null is returned.
|
|
///
|
|
LoopT *getLoopFor(const BlockT *BB) const {
|
|
typename std::map<BlockT *, LoopT *>::const_iterator I=
|
|
BBMap.find(const_cast<BlockT*>(BB));
|
|
return I != BBMap.end() ? I->second : 0;
|
|
}
|
|
|
|
/// operator[] - same as getLoopFor...
|
|
///
|
|
const LoopT *operator[](const BlockT *BB) const {
|
|
return getLoopFor(BB);
|
|
}
|
|
|
|
/// getLoopDepth - Return the loop nesting level of the specified block. A
|
|
/// depth of 0 means the block is not inside any loop.
|
|
///
|
|
unsigned getLoopDepth(const BlockT *BB) const {
|
|
const LoopT *L = getLoopFor(BB);
|
|
return L ? L->getLoopDepth() : 0;
|
|
}
|
|
|
|
// isLoopHeader - True if the block is a loop header node
|
|
bool isLoopHeader(BlockT *BB) const {
|
|
const LoopT *L = getLoopFor(BB);
|
|
return L && L->getHeader() == BB;
|
|
}
|
|
|
|
/// 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.
|
|
LoopT *removeLoop(iterator I) {
|
|
assert(I != end() && "Cannot remove end iterator!");
|
|
LoopT *L = *I;
|
|
assert(L->getParentLoop() == 0 && "Not a top-level loop!");
|
|
TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
|
|
return L;
|
|
}
|
|
|
|
/// 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 changeLoopFor(BlockT *BB, LoopT *L) {
|
|
LoopT *&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 changeTopLevelLoop(LoopT *OldLoop,
|
|
LoopT *NewLoop) {
|
|
typename std::vector<LoopT *>::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!");
|
|
}
|
|
|
|
/// addTopLevelLoop - This adds the specified loop to the collection of
|
|
/// top-level loops.
|
|
void addTopLevelLoop(LoopT *New) {
|
|
assert(New->getParentLoop() == 0 && "Loop already in subloop!");
|
|
TopLevelLoops.push_back(New);
|
|
}
|
|
|
|
/// 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 removeBlock(BlockT *BB) {
|
|
typename std::map<BlockT *, LoopT *>::iterator I = BBMap.find(BB);
|
|
if (I != BBMap.end()) {
|
|
for (LoopT *L = I->second; L; L = L->getParentLoop())
|
|
L->removeBlockFromLoop(BB);
|
|
|
|
BBMap.erase(I);
|
|
}
|
|
}
|
|
|
|
// Internals
|
|
|
|
static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
|
|
const LoopT *ParentLoop) {
|
|
if (SubLoop == 0) return true;
|
|
if (SubLoop == ParentLoop) return false;
|
|
return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
|
|
}
|
|
|
|
void Calculate(DominatorTreeBase<BlockT> &DT) {
|
|
BlockT *RootNode = DT.getRootNode()->getBlock();
|
|
|
|
for (df_iterator<BlockT*> NI = df_begin(RootNode),
|
|
NE = df_end(RootNode); NI != NE; ++NI)
|
|
if (LoopT *L = ConsiderForLoop(*NI, DT))
|
|
TopLevelLoops.push_back(L);
|
|
}
|
|
|
|
LoopT *ConsiderForLoop(BlockT *BB, DominatorTreeBase<BlockT> &DT) {
|
|
if (BBMap.find(BB) != BBMap.end()) return 0;// Haven't processed this node?
|
|
|
|
std::vector<BlockT *> TodoStack;
|
|
|
|
// Scan the predecessors of BB, checking to see if BB dominates any of
|
|
// them. This identifies backedges which target this node...
|
|
typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
|
|
for (typename InvBlockTraits::ChildIteratorType I =
|
|
InvBlockTraits::child_begin(BB), E = InvBlockTraits::child_end(BB);
|
|
I != E; ++I)
|
|
if (DT.dominates(BB, *I)) // If BB dominates it's predecessor...
|
|
TodoStack.push_back(*I);
|
|
|
|
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;
|
|
|
|
BlockT *EntryBlock = BB->getParent()->begin();
|
|
|
|
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.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 (LoopT *SubLoop =
|
|
const_cast<LoopT *>(getLoopFor(X)))
|
|
if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)){
|
|
// Remove the subloop from it's current parent...
|
|
assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L);
|
|
LoopT *SLP = SubLoop->ParentLoop; // SubLoopParent
|
|
typename std::vector<LoopT *>::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<Inverse<BlockT*> > 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<BlockT*>::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<BlockT*>::iterator I = L->Blocks.begin(),
|
|
E = L->Blocks.end(); I != E; ++I) {
|
|
typename std::map<BlockT*, LoopT *>::iterator BBMI = BBMap.find(*I);
|
|
if (BBMI == BBMap.end()) // Not in map yet...
|
|
BBMap.insert(BBMI, std::make_pair(*I, L)); // Must be at this level
|
|
}
|
|
|
|
// 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<BlockT *, LoopT *> 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, 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.
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return L;
|
|
}
|
|
|
|
/// 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) {
|
|
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<LoopT *>::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 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<unsigned>(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;
|
|
}
|
|
|
|
// Debugging
|
|
|
|
void 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*, LoopT*>::const_iterator I = BBMap.begin(),
|
|
E = BBMap.end(); I != E; ++I)
|
|
OS << "BB '" << I->first->getName() << "' level = "
|
|
<< I->second->getLoopDepth() << "\n";
|
|
#endif
|
|
}
|
|
};
|
|
|
|
class LoopInfo : public FunctionPass {
|
|
LoopInfoBase<BasicBlock, Loop> LI;
|
|
friend class LoopBase<BasicBlock, Loop>;
|
|
|
|
void operator=(const LoopInfo &); // do not implement
|
|
LoopInfo(const LoopInfo &); // do not implement
|
|
public:
|
|
static char ID; // Pass identification, replacement for typeid
|
|
|
|
LoopInfo() : FunctionPass(&ID) {}
|
|
|
|
LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; }
|
|
|
|
/// iterator/begin/end - The interface to the top-level loops in the current
|
|
/// function.
|
|
///
|
|
typedef LoopInfoBase<BasicBlock, Loop>::iterator iterator;
|
|
inline iterator begin() const { return LI.begin(); }
|
|
inline iterator end() const { return LI.end(); }
|
|
bool empty() const { return LI.empty(); }
|
|
|
|
/// getLoopFor - Return the inner most loop that BB lives in. If a basic
|
|
/// block is in no loop (for example the entry node), null is returned.
|
|
///
|
|
inline Loop *getLoopFor(const BasicBlock *BB) const {
|
|
return LI.getLoopFor(BB);
|
|
}
|
|
|
|
/// operator[] - same as getLoopFor...
|
|
///
|
|
inline const Loop *operator[](const BasicBlock *BB) const {
|
|
return LI.getLoopFor(BB);
|
|
}
|
|
|
|
/// getLoopDepth - Return the loop nesting level of the specified block. A
|
|
/// depth of 0 means the block is not inside any loop.
|
|
///
|
|
inline unsigned getLoopDepth(const BasicBlock *BB) const {
|
|
return LI.getLoopDepth(BB);
|
|
}
|
|
|
|
// isLoopHeader - True if the block is a loop header node
|
|
inline bool isLoopHeader(BasicBlock *BB) const {
|
|
return LI.isLoopHeader(BB);
|
|
}
|
|
|
|
/// runOnFunction - Calculate the natural loop information.
|
|
///
|
|
virtual bool runOnFunction(Function &F);
|
|
|
|
virtual void releaseMemory() { LI.releaseMemory(); }
|
|
|
|
virtual void print(std::ostream &O, const Module* M = 0) const {
|
|
LI.print(O, M);
|
|
}
|
|
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
|
|
|
|
/// 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.
|
|
inline Loop *removeLoop(iterator I) { return LI.removeLoop(I); }
|
|
|
|
/// 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.
|
|
inline void changeLoopFor(BasicBlock *BB, Loop *L) {
|
|
LI.changeLoopFor(BB, L);
|
|
}
|
|
|
|
/// changeTopLevelLoop - Replace the specified loop in the top-level loops
|
|
/// list with the indicated loop.
|
|
inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
|
|
LI.changeTopLevelLoop(OldLoop, NewLoop);
|
|
}
|
|
|
|
/// addTopLevelLoop - This adds the specified loop to the collection of
|
|
/// top-level loops.
|
|
inline void addTopLevelLoop(Loop *New) {
|
|
LI.addTopLevelLoop(New);
|
|
}
|
|
|
|
/// 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 removeBlock(BasicBlock *BB) {
|
|
LI.removeBlock(BB);
|
|
}
|
|
|
|
static bool isNotAlreadyContainedIn(const Loop *SubLoop,
|
|
const Loop *ParentLoop) {
|
|
return
|
|
LoopInfoBase<BasicBlock, Loop>::isNotAlreadyContainedIn(SubLoop,
|
|
ParentLoop);
|
|
}
|
|
};
|
|
|
|
|
|
// Allow clients to walk the list of nested loops...
|
|
template <> struct GraphTraits<const Loop*> {
|
|
typedef const Loop NodeType;
|
|
typedef LoopInfo::iterator ChildIteratorType;
|
|
|
|
static NodeType *getEntryNode(const Loop *L) { return L; }
|
|
static inline ChildIteratorType child_begin(NodeType *N) {
|
|
return N->begin();
|
|
}
|
|
static inline ChildIteratorType child_end(NodeType *N) {
|
|
return N->end();
|
|
}
|
|
};
|
|
|
|
template <> struct GraphTraits<Loop*> {
|
|
typedef Loop NodeType;
|
|
typedef LoopInfo::iterator ChildIteratorType;
|
|
|
|
static NodeType *getEntryNode(Loop *L) { return L; }
|
|
static inline ChildIteratorType child_begin(NodeType *N) {
|
|
return N->begin();
|
|
}
|
|
static inline ChildIteratorType child_end(NodeType *N) {
|
|
return N->end();
|
|
}
|
|
};
|
|
|
|
template<class BlockT, class LoopT>
|
|
void
|
|
LoopBase<BlockT, LoopT>::addBasicBlockToLoop(BlockT *NewBB,
|
|
LoopInfoBase<BlockT, LoopT> &LIB) {
|
|
assert((Blocks.empty() || LIB[getHeader()] == this) &&
|
|
"Incorrect LI specified for this loop!");
|
|
assert(NewBB && "Cannot add a null basic block to the loop!");
|
|
assert(LIB[NewBB] == 0 && "BasicBlock already in the loop!");
|
|
|
|
LoopT *L = static_cast<LoopT *>(this);
|
|
|
|
// Add the loop mapping to the LoopInfo object...
|
|
LIB.BBMap[NewBB] = L;
|
|
|
|
// Add the basic block to this loop and all parent loops...
|
|
while (L) {
|
|
L->Blocks.push_back(NewBB);
|
|
L = L->getParentLoop();
|
|
}
|
|
}
|
|
|
|
} // End llvm namespace
|
|
|
|
#endif
|