//===- PostDominators.cpp - Post-Dominator Calculation --------------------===//
//
+// 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 implements the post-dominator construction algorithms.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/PostDominators.h"
-#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Instructions.h"
#include "llvm/Support/CFG.h"
-#include "Support/DepthFirstIterator.h"
-#include "Support/SetOperations.h"
-using std::set;
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SetOperations.h"
+#include "PostDominatorCalculation.h"
+using namespace llvm;
//===----------------------------------------------------------------------===//
-// PostDominatorSet Implementation
+// PostDominatorTree Implementation
//===----------------------------------------------------------------------===//
-static RegisterAnalysis<PostDominatorSet>
-B("postdomset", "Post-Dominator Set Construction", true);
-
-// Postdominator set construction. This converts the specified function to only
-// have a single exit node (return stmt), then calculates the post dominance
-// sets for the function.
-//
-bool PostDominatorSet::runOnFunction(Function &F) {
- Doms.clear(); // Reset from the last time we were run...
- // Since we require that the unify all exit nodes pass has been run, we know
- // that there can be at most one return instruction in the function left.
- // Get it.
- //
- Root = getAnalysis<UnifyFunctionExitNodes>().getExitNode();
+char PostDominatorTree::ID = 0;
+char PostDominanceFrontier::ID = 0;
+static RegisterPass<PostDominatorTree>
+F("postdomtree", "Post-Dominator Tree Construction", true);
- if (Root == 0) { // No exit node for the function? Postdomsets are all empty
- for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
- Doms[FI] = DomSetType();
- return false;
- }
+unsigned PostDominatorTree::DFSPass(BasicBlock *V, unsigned N) {
+ std::vector<BasicBlock *> workStack;
+ SmallPtrSet<BasicBlock *, 32> Visited;
+ workStack.push_back(V);
- bool Changed;
do {
- Changed = false;
-
- set<const BasicBlock*> Visited;
- DomSetType WorkingSet;
- idf_iterator<BasicBlock*> It = idf_begin(Root), End = idf_end(Root);
- for ( ; It != End; ++It) {
- BasicBlock *BB = *It;
- succ_iterator PI = succ_begin(BB), PEnd = succ_end(BB);
- if (PI != PEnd) { // Is there SOME predecessor?
- // Loop until we get to a successor that has had it's dom set filled
- // in at least once. We are guaranteed to have this because we are
- // traversing the graph in DFO and have handled start nodes specially.
- //
- while (Doms[*PI].size() == 0) ++PI;
- WorkingSet = Doms[*PI];
-
- for (++PI; PI != PEnd; ++PI) { // Intersect all of the successor sets
- DomSetType &PredSet = Doms[*PI];
- if (PredSet.size())
- set_intersect(WorkingSet, PredSet);
- }
- }
-
- WorkingSet.insert(BB); // A block always dominates itself
- DomSetType &BBSet = Doms[BB];
- if (BBSet != WorkingSet) {
- BBSet.swap(WorkingSet); // Constant time operation!
- Changed = true; // The sets changed.
- }
- WorkingSet.clear(); // Clear out the set for next iteration
- }
- } while (Changed);
- return false;
-}
+ BasicBlock *currentBB = workStack.back();
+ InfoRec &CurVInfo = Info[currentBB];
-// getAnalysisUsage - This obviously provides a post-dominator set, but it also
-// requires the UnifyFunctionExitNodes pass.
-//
-void PostDominatorSet::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesAll();
- AU.addRequired<UnifyFunctionExitNodes>();
-}
-
-//===----------------------------------------------------------------------===//
-// ImmediatePostDominators Implementation
-//===----------------------------------------------------------------------===//
+ // Visit each block only once.
+ if (Visited.insert(currentBB)) {
+ CurVInfo.Semi = ++N;
+ CurVInfo.Label = currentBB;
+
+ Vertex.push_back(currentBB); // Vertex[n] = current;
+ // Info[currentBB].Ancestor = 0;
+ // Ancestor[n] = 0
+ // Child[currentBB] = 0;
+ CurVInfo.Size = 1; // Size[currentBB] = 1
+ }
-static RegisterAnalysis<ImmediatePostDominators>
-D("postidom", "Immediate Post-Dominators Construction", true);
+ // Visit children
+ bool visitChild = false;
+ for (pred_iterator PI = pred_begin(currentBB), PE = pred_end(currentBB);
+ PI != PE && !visitChild; ++PI) {
+ InfoRec &SuccVInfo = Info[*PI];
+ if (SuccVInfo.Semi == 0) {
+ SuccVInfo.Parent = currentBB;
+ if (!Visited.count(*PI)) {
+ workStack.push_back(*PI);
+ visitChild = true;
+ }
+ }
+ }
-//===----------------------------------------------------------------------===//
-// PostDominatorTree Implementation
-//===----------------------------------------------------------------------===//
+ // If all children are visited or if this block has no child then pop this
+ // block out of workStack.
+ if (!visitChild)
+ workStack.pop_back();
-static RegisterAnalysis<PostDominatorTree>
-F("postdomtree", "Post-Dominator Tree Construction", true);
+ } while (!workStack.empty());
-void PostDominatorTree::calculate(const PostDominatorSet &DS) {
- Nodes[Root] = new Node(Root, 0); // Add a node for the root...
-
- if (Root) {
- // Iterate over all nodes in depth first order...
- for (idf_iterator<BasicBlock*> I = idf_begin(Root), E = idf_end(Root);
- I != E; ++I) {
- BasicBlock *BB = *I;
- const DominatorSet::DomSetType &Dominators = DS.getDominators(BB);
- unsigned DomSetSize = Dominators.size();
- if (DomSetSize == 1) continue; // Root node... IDom = null
-
- // Loop over all dominators of this node. This corresponds to looping
- // over nodes in the dominator chain, looking for a node whose dominator
- // set is equal to the current nodes, except that the current node does
- // not exist in it. This means that it is one level higher in the dom
- // chain than the current node, and it is our idom! We know that we have
- // already added a DominatorTree node for our idom, because the idom must
- // be a predecessor in the depth first order that we are iterating through
- // the function.
- //
- DominatorSet::DomSetType::const_iterator I = Dominators.begin();
- DominatorSet::DomSetType::const_iterator End = Dominators.end();
- for (; I != End; ++I) { // Iterate over dominators...
- // All of our dominators should form a chain, where the number
- // of elements in the dominator set indicates what level the
- // node is at in the chain. We want the node immediately
- // above us, so it will have an identical dominator set,
- // except that BB will not dominate it... therefore it's
- // dominator set size will be one less than BB's...
- //
- if (DS.getDominators(*I).size() == DomSetSize - 1) {
- // We know that the immediate dominator should already have a node,
- // because we are traversing the CFG in depth first order!
- //
- Node *IDomNode = Nodes[*I];
- assert(IDomNode && "No node for IDOM?");
-
- // Add a new tree node for this BasicBlock, and link it as a child of
- // IDomNode
- Nodes[BB] = IDomNode->addChild(new Node(BB, IDomNode));
- break;
- }
- }
- }
- }
+ return N;
}
//===----------------------------------------------------------------------===//
// PostDominanceFrontier Implementation
//===----------------------------------------------------------------------===//
-static Register
Analysis<PostDominanceFrontier>
+static Register
Pass<PostDominanceFrontier>
H("postdomfrontier", "Post-Dominance Frontier Construction", true);
const DominanceFrontier::DomSetType &
-PostDominanceFrontier::calculate(const PostDominatorTree &DT,
- const DominatorTree::Node *Node) {
+PostDominanceFrontier::calculate(const PostDominatorTree &DT,
+ const DomTreeNode *Node) {
// Loop over CFG successors to calculate DFlocal[Node]
- BasicBlock *BB = Node->getNode();
+ BasicBlock *BB = Node->getBlock();
DomSetType &S = Frontiers[BB]; // The new set to fill in...
- if (!Root) return S;
-
- for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
- SI != SE; ++SI) {
- // Does Node immediately dominate this predeccessor?
- if (DT[*SI]->getIDom() != Node)
- S.insert(*SI);
- }
+ if (getRoots().empty()) return S;
+
+ if (BB)
+ for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
+ SI != SE; ++SI) {
+ // Does Node immediately dominate this predecessor?
+ DomTreeNode *SINode = DT[*SI];
+ if (SINode && SINode->getIDom() != Node)
+ S.insert(*SI);
+ }
// At this point, S is DFlocal. Now we union in DFup's of our children...
// Loop through and visit the nodes that Node immediately dominates (Node's
// children in the IDomTree)
//
- for (PostDominatorTree::Node::const_iterator
+ for (DomTreeNode::const_iterator
NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
- DominatorTree::Node *IDominee = *NI;
+ DomTreeNode *IDominee = *NI;
const DomSetType &ChildDF = calculate(DT, IDominee);
DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
for (; CDFI != CDFE; ++CDFI) {
- if (!Node->dominates(DT[*CDFI]))
- S.insert(*CDFI);
+ if (!DT.properlyDominates(Node, DT[*CDFI]))
+ S.insert(*CDFI);
}
}
return S;
}
-// stub - a dummy function to make linking work ok.
-void PostDominanceFrontier::stub() {
-}
+// Ensure that this .cpp file gets linked when PostDominators.h is used.
+DEFINING_FILE_FOR(PostDominanceFrontier)
projects / oota-llvm.git / blobdiff