[llvm-commits] CVS: llvm/include/llvm/Analysis/ET-Forest.h Dominators.h PostDominators.h
Chris Lattner
lattner at cs.uiuc.edu
Sun Jan 8 00:20:10 PST 2006
Changes in directory llvm/include/llvm/Analysis:
ET-Forest.h added (r1.1)
Dominators.h updated: 1.51 -> 1.52
PostDominators.h updated: 1.9 -> 1.10
---
Log message:
Initial implementation of the ET-Forest data structure for dominators and
post-dominators. This code was written/adapted by Daniel Berlin!
---
Diffs of the changes: (+447 -1)
Dominators.h | 116 ++++++++++++++++++++
ET-Forest.h | 309 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
PostDominators.h | 23 ++++
3 files changed, 447 insertions(+), 1 deletion(-)
Index: llvm/include/llvm/Analysis/ET-Forest.h
diff -c /dev/null llvm/include/llvm/Analysis/ET-Forest.h:1.1
*** /dev/null Sun Jan 8 02:20:08 2006
--- llvm/include/llvm/Analysis/ET-Forest.h Sun Jan 8 02:19:58 2006
***************
*** 0 ****
--- 1,309 ----
+ //===- llvm/Analysis/ET-Forest.h - ET-Forest implementation -----*- C++ -*-===//
+ //
+ // The LLVM Compiler Infrastructure
+ //
+ // This file was written by Daniel Berlin from code written by Pavel Nejedy, and
+ // is distributed under the University of Illinois Open Source License. See
+ // LICENSE.TXT for details.
+ //
+ //===----------------------------------------------------------------------===//
+ //
+ // This file defines the following classes:
+ // 1. ETNode: A node in the ET forest.
+ // 2. ETOccurrence: An occurrence of the node in the splay tree
+ // storing the DFS path information.
+ //
+ // The ET-forest structure is described in:
+ // D. D. Sleator and R. E. Tarjan. A data structure for dynamic trees.
+ // J. G'omput. System Sci., 26(3):362 381, 1983.
+ //
+ // Basically, the ET-Forest is storing the dominator tree (ETNode),
+ // and a splay tree containing the depth first path information for
+ // those nodes (ETOccurrence). This enables us to answer queries
+ // about domination (DominatedBySlow), and ancestry (NCA) in
+ // logarithmic time, and perform updates to the information in
+ // logarithmic time.
+ //
+ //===----------------------------------------------------------------------===//
+
+ #ifndef LLVM_ANALYSIS_ETFOREST_H
+ #define LLVM_ANALYSIS_ETFOREST_H
+
+ #include <cassert>
+
+ namespace llvm {
+ class ETNode;
+
+ /// ETOccurrence - An occurrence for a node in the et tree
+ ///
+ /// The et occurrence tree is really storing the sequences you get from
+ /// doing a DFS over the ETNode's. It is stored as a modified splay
+ /// tree.
+ /// ET occurrences can occur at multiple places in the ordering depending
+ /// on how many ET nodes have it as their father. To handle
+ /// this, they are separate from the nodes.
+ ///
+ class ETOccurrence {
+ public:
+ ETOccurrence(ETNode *n): OccFor(n), Parent(NULL), Left(NULL), Right(NULL),
+ Depth(0), Min(0), MinOccurrence(this) {};
+
+ void setParent(ETOccurrence *n) {
+ Parent = n;
+ }
+
+ // Add D to our current depth
+ void setDepthAdd(int d) {
+ Min += d;
+ Depth += d;
+ }
+
+ // Reset our depth to D
+ void setDepth(int d) {
+ Min += d - Depth;
+ Depth = d;
+ }
+
+ // Set Left to N
+ void setLeft(ETOccurrence *n) {
+ assert(n != this && "Trying to set our left to ourselves");
+ Left = n;
+ if (n)
+ n->setParent(this);
+ }
+
+ // Set Right to N
+ void setRight(ETOccurrence *n) {
+ assert(n != this && "Trying to set our right to ourselves");
+ Right = n;
+ if (n)
+ n->setParent(this);
+ }
+
+ // Splay us to the root of the tree
+ void Splay(void);
+
+ // Recompute the minimum occurrence for this occurrence.
+ void recomputeMin(void) {
+ ETOccurrence *themin = Left;
+
+ // The min may be our Right, too.
+ if (!themin || (Right && themin->Min > Right->Min))
+ themin = Right;
+
+ if (themin && themin->Min < 0) {
+ Min = themin->Min + Depth;
+ MinOccurrence = themin->MinOccurrence;
+ } else {
+ Min = Depth;
+ MinOccurrence = this;
+ }
+ }
+ private:
+ friend class ETNode;
+
+ // Node we represent
+ ETNode *OccFor;
+
+ // Parent in the splay tree
+ ETOccurrence *Parent;
+
+ // Left Son in the splay tree
+ ETOccurrence *Left;
+
+ // Right Son in the splay tree
+ ETOccurrence *Right;
+
+ // Depth of the node is the sum of the depth on the path to the
+ // root.
+ int Depth;
+
+ // Subtree occurrence's minimum depth
+ int Min;
+
+ // Subtree occurrence with minimum depth
+ ETOccurrence *MinOccurrence;
+ };
+
+
+ class ETNode {
+ public:
+ ETNode(void *d) : data(d), Father(NULL), Left(NULL),
+ Right(NULL), Son(NULL), ParentOcc(NULL) {
+ RightmostOcc = new ETOccurrence(this);
+ };
+
+ // This does *not* maintain the tree structure.
+ // If you want to remove a node from the forest structure, use
+ // removeFromForest()
+ ~ETNode() {
+ delete RightmostOcc;
+ }
+
+ void removeFromForest() {
+ // Split us away from all our sons.
+ while (Son)
+ Son->Split();
+
+ // And then split us away from our father.
+ if (Father)
+ Father->Split();
+ }
+
+ // Split us away from our parents and children, so that we can be
+ // reparented. NB: setFather WILL NOT DO WHAT YOU WANT IF YOU DO NOT
+ // SPLIT US FIRST.
+ void Split();
+
+ // Set our parent node to the passed in node
+ void setFather(ETNode *);
+
+ // Nearest Common Ancestor of two et nodes.
+ ETNode *NCA(ETNode *);
+
+ // Return true if we are below the passed in node in the forest.
+ bool Below(ETNode *);
+ /*
+ Given a dominator tree, we can determine whether one thing
+ dominates another in constant time by using two DFS numbers:
+
+ 1. The number for when we visit a node on the way down the tree
+ 2. The number for when we visit a node on the way back up the tree
+
+ You can view these as bounds for the range of dfs numbers the
+ nodes in the subtree of the dominator tree rooted at that node
+ will contain.
+
+ The dominator tree is always a simple acyclic tree, so there are
+ only three possible relations two nodes in the dominator tree have
+ to each other:
+
+ 1. Node A is above Node B (and thus, Node A dominates node B)
+
+ A
+ |
+ C
+ / \
+ B D
+
+
+ In the above case, DFS_Number_In of A will be <= DFS_Number_In of
+ B, and DFS_Number_Out of A will be >= DFS_Number_Out of B. This is
+ because we must hit A in the dominator tree *before* B on the walk
+ down, and we will hit A *after* B on the walk back up
+
+ 2. Node A is below node B (and thus, node B dominates node B)
+
+ B
+ |
+ A
+ / \
+ C D
+
+ In the above case, DFS_Number_In of A will be >= DFS_Number_In of
+ B, and DFS_Number_Out of A will be <= DFS_Number_Out of B.
+
+ This is because we must hit A in the dominator tree *after* B on
+ the walk down, and we will hit A *before* B on the walk back up
+
+ 3. Node A and B are siblings (and thus, neither dominates the other)
+
+ C
+ |
+ D
+ / \
+ A B
+
+ In the above case, DFS_Number_In of A will *always* be <=
+ DFS_Number_In of B, and DFS_Number_Out of A will *always* be <=
+ DFS_Number_Out of B. This is because we will always finish the dfs
+ walk of one of the subtrees before the other, and thus, the dfs
+ numbers for one subtree can't intersect with the range of dfs
+ numbers for the other subtree. If you swap A and B's position in
+ the dominator tree, the comparison changes direction, but the point
+ is that both comparisons will always go the same way if there is no
+ dominance relationship.
+
+ Thus, it is sufficient to write
+
+ A_Dominates_B(node A, node B) {
+ return DFS_Number_In(A) <= DFS_Number_In(B) &&
+ DFS_Number_Out(A) >= DFS_Number_Out(B);
+ }
+
+ A_Dominated_by_B(node A, node B) {
+ return DFS_Number_In(A) >= DFS_Number_In(A) &&
+ DFS_Number_Out(A) <= DFS_Number_Out(B);
+ }
+ */
+ bool DominatedBy(ETNode *other) const {
+ return this->DFSNumIn >= other->DFSNumIn &&
+ this->DFSNumOut <= other->DFSNumOut;
+ }
+
+ // This method is slower, but doesn't require the DFS numbers to
+ // be up to date.
+ bool DominatedBySlow(ETNode *other) {
+ return this->Below(other);
+ }
+
+ void assignDFSNumber(int &num) {
+ DFSNumIn = num++;
+
+ if (Son) {
+ Son->assignDFSNumber(num);
+ for (ETNode *son = Son->Right; son != Son; son = son->Right)
+ son->assignDFSNumber(num);
+ }
+ DFSNumOut = num++;
+ }
+
+ bool hasFather() const {
+ return Father != NULL;
+ }
+
+ // Do not let people play around with fathers.
+ const ETNode *getFather() const {
+ return Father;
+ }
+
+ template <typename T>
+ T *getData() const {
+ return static_cast<T*>(data);
+ }
+
+ unsigned getDFSNumIn() const {
+ return DFSNumIn;
+ }
+
+ unsigned getDFSNumOut() const {
+ return DFSNumOut;
+ }
+
+ private:
+ // Data represented by the node
+ void *data;
+
+ // DFS Numbers
+ unsigned DFSNumIn, DFSNumOut;
+
+ // Father
+ ETNode *Father;
+
+ // Brothers. Node, this ends up being a circularly linked list.
+ // Thus, if you want to get all the brothers, you need to stop when
+ // you hit node == this again.
+ ETNode *Left, *Right;
+
+ // First Son
+ ETNode *Son;
+
+ // Rightmost occurrence for this node
+ ETOccurrence *RightmostOcc;
+
+ // Parent occurrence for this node
+ ETOccurrence *ParentOcc;
+ };
+ } // end llvm namespace
+
+ #endif
Index: llvm/include/llvm/Analysis/Dominators.h
diff -u llvm/include/llvm/Analysis/Dominators.h:1.51 llvm/include/llvm/Analysis/Dominators.h:1.52
--- llvm/include/llvm/Analysis/Dominators.h:1.51 Mon Nov 28 19:07:12 2005
+++ llvm/include/llvm/Analysis/Dominators.h Sun Jan 8 02:19:58 2006
@@ -13,7 +13,9 @@
// 2. DominatorSet: Calculates the [reverse] dominator set for a function
// 3. DominatorTree: Represent the ImmediateDominator as an explicit tree
// structure.
-// 4. DominanceFrontier: Calculate and hold the dominance frontier for a
+// 4. ETForest: Efficient data structure for dominance comparisons and
+// nearest-common-ancestor queries.
+// 5. DominanceFrontier: Calculate and hold the dominance frontier for a
// function.
//
// These data structures are listed in increasing order of complexity. It
@@ -25,6 +27,7 @@
#ifndef LLVM_ANALYSIS_DOMINATORS_H
#define LLVM_ANALYSIS_DOMINATORS_H
+#include "llvm/Analysis/ET-Forest.h"
#include "llvm/Pass.h"
#include <set>
@@ -389,6 +392,116 @@
//===-------------------------------------
+/// ET-Forest Class - Class used to construct forwards and backwards
+/// ET-Forests
+///
+struct ETForestBase : public DominatorBase {
+ ETForestBase(bool isPostDom) : DominatorBase(isPostDom), Nodes(),
+ DFSInfoValid(false) {}
+
+ virtual void releaseMemory() { reset(); }
+
+ typedef std::map<BasicBlock*, ETNode*> ETMapType;
+
+
+ /// dominates - Return true if A dominates B.
+ ///
+ inline bool dominates(BasicBlock *A, BasicBlock *B) const {
+ if (A == B)
+ return true;
+
+ ETNode *NodeA = getNode(A);
+ ETNode *NodeB = getNode(B);
+
+ if (DFSInfoValid)
+ return NodeB->DominatedBy(NodeA);
+ else
+ return NodeB->DominatedBySlow(NodeA);
+ }
+
+ /// properlyDominates - Return true if A dominates B and A != B.
+ ///
+ bool properlyDominates(BasicBlock *A, BasicBlock *B) const {
+ return dominates(A, B) && A != B;
+ }
+
+ /// Return the nearest common dominator of A and B.
+ BasicBlock *nearestCommonDominator(BasicBlock *A, BasicBlock *B) const {
+ ETNode *NodeA = getNode(A);
+ ETNode *NodeB = getNode(B);
+
+ ETNode *Common = NodeA->NCA(NodeB);
+ if (!Common)
+ return NULL;
+ return Common->getData<BasicBlock>();
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<ImmediateDominators>();
+ }
+ //===--------------------------------------------------------------------===//
+ // API to update Forest information based on modifications
+ // to the CFG...
+
+ /// addNewBlock - Add a new block to the CFG, with the specified immediate
+ /// dominator.
+ ///
+ void addNewBlock(BasicBlock *BB, BasicBlock *IDom);
+
+ /// setImmediateDominator - Update the immediate dominator information to
+ /// change the current immediate dominator for the specified block
+ /// to another block. This method requires that BB for NewIDom
+ /// already have an ETNode, otherwise just use addNewBlock.
+ ///
+ void setImmediateDominator(BasicBlock *BB, BasicBlock *NewIDom);
+ /// print - Convert to human readable form
+ ///
+ virtual void print(std::ostream &OS, const Module* = 0) const;
+protected:
+ /// getNode - return the (Post)DominatorTree node for the specified basic
+ /// block. This is the same as using operator[] on this class.
+ ///
+ inline ETNode *getNode(BasicBlock *BB) const {
+ ETMapType::const_iterator i = Nodes.find(BB);
+ return (i != Nodes.end()) ? i->second : 0;
+ }
+
+ inline ETNode *operator[](BasicBlock *BB) const {
+ return getNode(BB);
+ }
+
+ void reset();
+ ETMapType Nodes;
+ bool DFSInfoValid;
+
+};
+
+//==-------------------------------------
+/// ETForest Class - Concrete subclass of ETForestBase that is used to
+/// compute a forwards ET-Forest.
+
+struct ETForest : public ETForestBase {
+ ETForest() : ETForestBase(false) {}
+
+ BasicBlock *getRoot() const {
+ assert(Roots.size() == 1 && "Should always have entry node!");
+ return Roots[0];
+ }
+
+ virtual bool runOnFunction(Function &F) {
+ reset(); // Reset from the last time we were run...
+ ImmediateDominators &ID = getAnalysis<ImmediateDominators>();
+ Roots = ID.getRoots();
+ calculate(ID);
+ return false;
+ }
+
+ void calculate(const ImmediateDominators &ID);
+ ETNode *getNodeForBlock(BasicBlock *BB);
+};
+
+//===-------------------------------------
/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
/// compute a normal dominator tree.
///
@@ -518,6 +631,7 @@
const DominatorTree::Node *Node);
};
+
// Make sure that any clients of this file link in Dominators.cpp
static IncludeFile
DOMINATORS_INCLUDE_FILE((void*)&DominatorSet::stub);
Index: llvm/include/llvm/Analysis/PostDominators.h
diff -u llvm/include/llvm/Analysis/PostDominators.h:1.9 llvm/include/llvm/Analysis/PostDominators.h:1.10
--- llvm/include/llvm/Analysis/PostDominators.h:1.9 Thu Apr 21 15:16:32 2005
+++ llvm/include/llvm/Analysis/PostDominators.h Sun Jan 8 02:19:58 2006
@@ -84,6 +84,29 @@
};
+/// PostETForest Class - Concrete subclass of ETForestBase that is used to
+/// compute a forwards post-dominator ET-Forest.
+struct PostETForest : public ETForestBase {
+ PostETForest() : ETForestBase(true) {}
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<ImmediatePostDominators>();
+ }
+
+ virtual bool runOnFunction(Function &F) {
+ reset(); // Reset from the last time we were run...
+ ImmediatePostDominators &ID = getAnalysis<ImmediatePostDominators>();
+ Roots = ID.getRoots();
+ calculate(ID);
+ return false;
+ }
+
+ void calculate(const ImmediatePostDominators &ID);
+ ETNode *getNodeForBlock(BasicBlock *BB);
+};
+
+
/// PostDominanceFrontier Class - Concrete subclass of DominanceFrontier that is
/// used to compute the a post-dominance frontier.
///
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