It's not necessary to do rounding for alloca operations when the requested

alignment is equal to the stack alignment.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 363 insertions, 0 deletions

diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h
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+++ b/include/llvm/Analysis/LoopInfo.h
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+//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===//
+//
+//                     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 natural
+// loops may actually be several loops that share the same header node.
+//
+// This analysis calculates the nesting structure of loops in a function.  For
+// each natural loop identified, this analysis identifies natural loops
+// contained entirely within the loop and the basic blocks the make up the loop.
+//
+// It can calculate on the fly various bits of information, for example:
+//
+//  * whether there is a preheader for the loop
+//  * the number of back edges to the header
+//  * whether or not a particular block branches out of the loop
+//  * the successor blocks of the loop
+//  * the loop depth
+//  * the trip count
+//  * etc...
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_LOOP_INFO_H
+#define LLVM_ANALYSIS_LOOP_INFO_H
+
+#include "llvm/Pass.h"
+#include "llvm/ADT/GraphTraits.h"
+
+namespace llvm {
+
+class DominatorTree;
+class LoopInfo;
+class PHINode;
+class Instruction;
+
+//===----------------------------------------------------------------------===//
+/// Loop class - Instances of this class are used to represent loops that are
+/// detected in the flow graph
+///
+class Loop {
+  Loop *ParentLoop;
+  std::vector<Loop*> SubLoops;       // Loops contained entirely within this one
+  std::vector<BasicBlock*> Blocks;   // First entry is the header node
+
+  Loop(const Loop &);                  // DO NOT IMPLEMENT
+  const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
+public:
+  /// Loop ctor - This creates an empty loop.
+  Loop() : ParentLoop(0) {}
+  ~Loop() {
+    for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
+      delete SubLoops[i];
+  }
+
+  unsigned getLoopDepth() const {
+    unsigned D = 0;
+    for (const Loop *CurLoop = this; CurLoop; CurLoop = CurLoop->ParentLoop)
+      ++D;
+    return D;
+  }
+  BasicBlock *getHeader() const { return Blocks.front(); }
+  Loop *getParentLoop() const { return ParentLoop; }
+
+  /// contains - Return true of the specified basic block is in this loop
+  ///
+  bool contains(const BasicBlock *BB) const;
+
+  /// iterator/begin/end - Return the loops contained entirely within this loop.
+  ///
+  const std::vector<Loop*> &getSubLoops() const { return SubLoops; }
+  typedef std::vector<Loop*>::const_iterator iterator;
+  iterator begin() const { return SubLoops.begin(); }
+  iterator end() const { return SubLoops.end(); }
+
+  /// getBlocks - Get a list of the basic blocks which make up this loop.
+  ///
+  const std::vector<BasicBlock*> &getBlocks() const { return Blocks; }
+  typedef std::vector<BasicBlock*>::const_iterator block_iterator;
+  block_iterator block_begin() const { return Blocks.begin(); }
+  block_iterator block_end() const { return Blocks.end(); }
+
+  /// isLoopExit - True if terminator in the block can branch to another block
+  /// that is outside of the current loop.
+  ///
+  bool isLoopExit(const BasicBlock *BB) const;
+
+  /// getNumBackEdges - Calculate the number of back edges to the loop header
+  ///
+  unsigned getNumBackEdges() const;
+
+  /// isLoopInvariant - Return true if the specified value is loop invariant
+  ///
+  bool isLoopInvariant(Value *V) const;
+
+  //===--------------------------------------------------------------------===//
+  // APIs for simple analysis of the loop.
+  //
+  // Note that all of these methods can fail on general loops (ie, there may not
+  // be a preheader, etc).  For best success, the loop simplification and
+  // induction variable canonicalization pass should be used to normalize loops
+  // for easy analysis.  These methods assume canonical loops.
+
+  /// 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 getExitingBlocks(std::vector<BasicBlock*> &Blocks) const;
+
+  /// getExitBlocks - Return all of the successor blocks of this loop.  These
+  /// are the blocks _outside of the current loop_ which are branched to.
+  ///
+  void getExitBlocks(std::vector<BasicBlock*> &Blocks) const;
+
+  /// 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 getUniqueExitBlocks(std::vector<BasicBlock*> &ExitBlocks) const;
+
+  /// 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 *getLoopPreheader() const;
+
+  /// 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 *getLoopLatch() 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.
+  ///
+  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.
+  ///
+  Value *getTripCount() const;
+  
+  /// isLCSSAForm - Return true if the Loop is in LCSSA form
+  bool isLCSSAForm() const;
+
+  //===--------------------------------------------------------------------===//
+  // APIs for updating loop information after changing the CFG
+  //
+
+  /// addBasicBlockToLoop - This method 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 addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI);
+
+  /// replaceChildLoopWith - This is used when splitting loops up.  It replaces
+  /// the OldChild entry in our children list with NewChild, and updates the
+  /// parent pointer of OldChild to be null and the NewChild to be this loop.
+  /// This updates the loop depth of the new child.
+  void replaceChildLoopWith(Loop *OldChild, Loop *NewChild);
+
+  /// addChildLoop - Add the specified loop to be a child of this loop.  This
+  /// updates the loop depth of the new child.
+  ///
+  void addChildLoop(Loop *NewChild);
+
+  /// 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 *removeChildLoop(iterator OldChild);
+
+  /// addBlockEntry - This adds a basic block directly to the basic block list.
+  /// This should only be used by transformations that create new loops.  Other
+  /// transformations should use addBasicBlockToLoop.
+  void addBlockEntry(BasicBlock *BB) {
+    Blocks.push_back(BB);
+  }
+
+  /// moveToHeader - This method is used to move BB (which must be part of this
+  /// loop) to be the loop header of the loop (the block that dominates all
+  /// others).
+  void moveToHeader(BasicBlock *BB) {
+    if (Blocks[0] == BB) return;
+    for (unsigned i = 0; ; ++i) {
+      assert(i != Blocks.size() && "Loop does not contain BB!");
+      if (Blocks[i] == BB) {
+        Blocks[i] = Blocks[0];
+        Blocks[0] = BB;
+        return;
+      }
+    }
+  }
+
+  /// removeBlockFromLoop - This removes the specified basic block from the
+  /// current loop, updating the Blocks as appropriate.  This does not update
+  /// the mapping in the LoopInfo class.
+  void removeBlockFromLoop(BasicBlock *BB);
+
+  void print(std::ostream &O, unsigned Depth = 0) const;
+  void print(std::ostream *O, unsigned Depth = 0) const {
+    if (O) print(*O, Depth);
+  }
+  void dump() const;
+private:
+  friend class LoopInfo;
+  Loop(BasicBlock *BB) : ParentLoop(0) {
+    Blocks.push_back(BB);
+  }
+};
+
+
+
+//===----------------------------------------------------------------------===//
+/// LoopInfo - This class builds and contains all of the top level loop
+/// structures in the specified function.
+///
+class LoopInfo : public FunctionPass {
+  // BBMap - Mapping of basic blocks to the inner most loop they occur in
+  std::map<BasicBlock*, Loop*> BBMap;
+  std::vector<Loop*> TopLevelLoops;
+  friend class Loop;
+public:
+  static char ID; // Pass identification, replacement for typeid
+
+  LoopInfo() : FunctionPass((intptr_t)&ID) {}
+  ~LoopInfo() { releaseMemory(); }
+
+  /// iterator/begin/end - The interface to the top-level loops in the current
+  /// function.
+  ///
+  typedef std::vector<Loop*>::const_iterator iterator;
+  iterator begin() const { return TopLevelLoops.begin(); }
+  iterator end() const { return TopLevelLoops.end(); }
+
+  /// 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.
+  ///
+  Loop *getLoopFor(const BasicBlock *BB) const {
+    std::map<BasicBlock *, Loop*>::const_iterator I=
+      BBMap.find(const_cast<BasicBlock*>(BB));
+    return I != BBMap.end() ? I->second : 0;
+  }
+
+  /// operator[] - same as getLoopFor...
+  ///
+  const Loop *operator[](const BasicBlock *BB) const {
+    return getLoopFor(BB);
+  }
+
+  /// getLoopDepth - Return the loop nesting level of the specified block...
+  ///
+  unsigned getLoopDepth(const BasicBlock *BB) const {
+    const Loop *L = getLoopFor(BB);
+    return L ? L->getLoopDepth() : 0;
+  }
+
+  // isLoopHeader - True if the block is a loop header node
+  bool isLoopHeader(BasicBlock *BB) const {
+    const Loop *L = getLoopFor(BB);
+    return L && L->getHeader() == BB;
+  }
+
+  /// runOnFunction - Calculate the natural loop information.
+  ///
+  virtual bool runOnFunction(Function &F);
+
+  virtual void releaseMemory();
+
+  void print(std::ostream &O, const Module* = 0) const;
+  void print(std::ostream *O, const Module* M = 0) const {
+    if (O) 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.
+  Loop *removeLoop(iterator 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.
+  void changeLoopFor(BasicBlock *BB, Loop *L);
+
+  /// changeTopLevelLoop - Replace the specified loop in the top-level loops
+  /// list with the indicated loop.
+  void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop);
+
+  /// addTopLevelLoop - This adds the specified loop to the collection of
+  /// top-level loops.
+  void addTopLevelLoop(Loop *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(BasicBlock *BB);
+
+private:
+  void Calculate(DominatorTree &DT);
+  Loop *ConsiderForLoop(BasicBlock *BB, DominatorTree &DT);
+  void MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent);
+  void InsertLoopInto(Loop *L, Loop *Parent);
+};
+
+
+// Allow clients to walk the list of nested loops...
+template <> struct GraphTraits<const Loop*> {
+  typedef const Loop NodeType;
+  typedef std::vector<Loop*>::const_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 std::vector<Loop*>::const_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();
+  }
+};
+
+} // End llvm namespace
+
+// Make sure that any clients of this file link in LoopInfo.cpp
+FORCE_DEFINING_FILE_TO_BE_LINKED(LoopInfo)
+
+#endif