+//==- PostDominatorCalculation.h - Post-Dominator Calculation ----*- C++ -*-==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by Owen Anderson and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// PostDominatorTree calculation implementation.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_POST_DOMINATOR_CALCULATION_H
+#define LLVM_ANALYSIS_POST_DOMINATOR_CALCULATION_H
+
+#include "llvm/Analysis/PostDominators.h"
+
+namespace llvm {
+
+void PDTCompress(PostDominatorTree& PDT, BasicBlock *V,
+ PostDominatorTree::InfoRec &VInfo) {
+ BasicBlock *VAncestor = VInfo.Ancestor;
+ PostDominatorTree::InfoRec &VAInfo = PDT.Info[VAncestor];
+ if (VAInfo.Ancestor == 0)
+ return;
+
+ PDTCompress(PDT, VAncestor, VAInfo);
+
+ BasicBlock *VAncestorLabel = VAInfo.Label;
+ BasicBlock *VLabel = VInfo.Label;
+ if (PDT.Info[VAncestorLabel].Semi < PDT.Info[VLabel].Semi)
+ VInfo.Label = VAncestorLabel;
+
+ VInfo.Ancestor = VAInfo.Ancestor;
+}
+
+BasicBlock *PDTEval(PostDominatorTree& PDT, BasicBlock *V) {
+ PostDominatorTree::InfoRec &VInfo = PDT.Info[V];
+
+ // Higher-complexity but faster implementation
+ if (VInfo.Ancestor == 0)
+ return V;
+ PDTCompress(PDT, V, VInfo);
+ return VInfo.Label;
+}
+
+void PDTLink(PostDominatorTree& PDT, BasicBlock *V, BasicBlock *W,
+ PostDominatorTree::InfoRec &WInfo) {
+ // Higher-complexity but faster implementation
+ WInfo.Ancestor = V;
+}
+
+void PDTcalculate(PostDominatorTree& PDT, Function &F) {
+ // Step #0: Scan the function looking for the root nodes of the post-dominance
+ // relationships. These blocks, which have no successors, end with return and
+ // unwind instructions.
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
+ TerminatorInst *Insn = I->getTerminator();
+ if (Insn->getNumSuccessors() == 0) {
+ // Unreachable block is not a root node.
+ if (!isa<UnreachableInst>(Insn))
+ PDT.Roots.push_back(I);
+ }
+
+ // Prepopulate maps so that we don't get iterator invalidation issues later.
+ PDT.IDoms[I] = 0;
+ PDT.DomTreeNodes[I] = 0;
+ }
+
+ PDT.Vertex.push_back(0);
+
+ // Step #1: Number blocks in depth-first order and initialize variables used
+ // in later stages of the algorithm.
+ unsigned N = 0;
+ for (unsigned i = 0, e = PDT.Roots.size(); i != e; ++i)
+ N = PDT.DFSPass(PDT.Roots[i], N);
+
+ for (unsigned i = N; i >= 2; --i) {
+ BasicBlock *W = PDT.Vertex[i];
+ PostDominatorTree::InfoRec &WInfo = PDT.Info[W];
+
+ // Step #2: Calculate the semidominators of all vertices
+ for (succ_iterator SI = succ_begin(W), SE = succ_end(W); SI != SE; ++SI)
+ if (PDT.Info.count(*SI)) { // Only if this predecessor is reachable!
+ unsigned SemiU = PDT.Info[PDTEval(PDT, *SI)].Semi;
+ if (SemiU < WInfo.Semi)
+ WInfo.Semi = SemiU;
+ }
+
+ PDT.Info[PDT.Vertex[WInfo.Semi]].Bucket.push_back(W);
+
+ BasicBlock *WParent = WInfo.Parent;
+ PDTLink(PDT, WParent, W, WInfo);
+
+ // Step #3: Implicitly define the immediate dominator of vertices
+ std::vector<BasicBlock*> &WParentBucket = PDT.Info[WParent].Bucket;
+ while (!WParentBucket.empty()) {
+ BasicBlock *V = WParentBucket.back();
+ WParentBucket.pop_back();
+ BasicBlock *U = PDTEval(PDT, V);
+ PDT.IDoms[V] = PDT.Info[U].Semi < PDT.Info[V].Semi ? U : WParent;
+ }
+ }
+
+ // Step #4: Explicitly define the immediate dominator of each vertex
+ for (unsigned i = 2; i <= N; ++i) {
+ BasicBlock *W = PDT.Vertex[i];
+ BasicBlock *&WIDom = PDT.IDoms[W];
+ if (WIDom != PDT.Vertex[PDT.Info[W].Semi])
+ WIDom = PDT.IDoms[WIDom];
+ }
+
+ if (PDT.Roots.empty()) return;
+
+ // Add a node for the root. This node might be the actual root, if there is
+ // one exit block, or it may be the virtual exit (denoted by (BasicBlock *)0)
+ // which postdominates all real exits if there are multiple exit blocks.
+ BasicBlock *Root = PDT.Roots.size() == 1 ? PDT.Roots[0] : 0;
+ PDT.DomTreeNodes[Root] = PDT.RootNode = new DomTreeNode(Root, 0);
+
+ // Loop over all of the reachable blocks in the function...
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+ if (BasicBlock *ImmPostDom = PDT.getIDom(I)) { // Reachable block.
+ DomTreeNode *&BBNode = PDT.DomTreeNodes[I];
+ if (!BBNode) { // Haven't calculated this node yet?
+ // Get or calculate the node for the immediate dominator
+ DomTreeNode *IPDomNode = PDT.getNodeForBlock(ImmPostDom);
+
+ // Add a new tree node for this BasicBlock, and link it as a child of
+ // IDomNode
+ DomTreeNode *C = new DomTreeNode(I, IPDomNode);
+ PDT.DomTreeNodes[I] = C;
+ BBNode = IPDomNode->addChild(C);
+ }
+ }
+
+ // Free temporary memory used to construct idom's
+ PDT.IDoms.clear();
+ PDT.Info.clear();
+ std::vector<BasicBlock*>().swap(PDT.Vertex);
+
+ // Start out with the DFS numbers being invalid. Let them be computed if
+ // demanded.
+ PDT.DFSInfoValid = false;
+}
+
+}
+#endif
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