--- /dev/null
+//==- llvm/VMCore/DominatorCalculation.h - 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.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_VMCORE_DOMINATOR_CALCULATION_H
+#define LLVM_VMCORE_DOMINATOR_CALCULATION_H
+
+#include "llvm/Analysis/Dominators.h"
+
+//===----------------------------------------------------------------------===//
+//
+// DominatorTree construction - This pass constructs immediate dominator
+// information for a flow-graph based on the algorithm described in this
+// document:
+//
+// A Fast Algorithm for Finding Dominators in a Flowgraph
+// T. Lengauer & R. Tarjan, ACM TOPLAS July 1979, pgs 121-141.
+//
+// This implements both the O(n*ack(n)) and the O(n*log(n)) versions of EVAL and
+// LINK, but it turns out that the theoretically slower O(n*log(n))
+// implementation is actually faster than the "efficient" algorithm (even for
+// large CFGs) because the constant overheads are substantially smaller. The
+// lower-complexity version can be enabled with the following #define:
+//
+#define BALANCE_IDOM_TREE 0
+//
+//===----------------------------------------------------------------------===//
+
+namespace llvm {
+
+void DTCompress(DominatorTree& DT, BasicBlock *VIn) {
+
+ std::vector<BasicBlock *> Work;
+ SmallPtrSet<BasicBlock *, 32> Visited;
+ BasicBlock *VInAncestor = DT.Info[VIn].Ancestor;
+ DominatorTree::InfoRec &VInVAInfo = DT.Info[VInAncestor];
+
+ if (VInVAInfo.Ancestor != 0)
+ Work.push_back(VIn);
+
+ while (!Work.empty()) {
+ BasicBlock *V = Work.back();
+ DominatorTree::InfoRec &VInfo = DT.Info[V];
+ BasicBlock *VAncestor = VInfo.Ancestor;
+ DominatorTree::InfoRec &VAInfo = DT.Info[VAncestor];
+
+ // Process Ancestor first
+ if (Visited.insert(VAncestor) &&
+ VAInfo.Ancestor != 0) {
+ Work.push_back(VAncestor);
+ continue;
+ }
+ Work.pop_back();
+
+ // Update VInfo based on Ancestor info
+ if (VAInfo.Ancestor == 0)
+ continue;
+ BasicBlock *VAncestorLabel = VAInfo.Label;
+ BasicBlock *VLabel = VInfo.Label;
+ if (DT.Info[VAncestorLabel].Semi < DT.Info[VLabel].Semi)
+ VInfo.Label = VAncestorLabel;
+ VInfo.Ancestor = VAInfo.Ancestor;
+ }
+}
+
+BasicBlock *DTEval(DominatorTree& DT, BasicBlock *V) {
+ DominatorTree::InfoRec &VInfo = DT.Info[V];
+#if !BALANCE_IDOM_TREE
+ // Higher-complexity but faster implementation
+ if (VInfo.Ancestor == 0)
+ return V;
+ DTCompress(DT, V);
+ return VInfo.Label;
+#else
+ // Lower-complexity but slower implementation
+ if (VInfo.Ancestor == 0)
+ return VInfo.Label;
+ DTCompress(DT, V);
+ BasicBlock *VLabel = VInfo.Label;
+
+ BasicBlock *VAncestorLabel = DT.Info[VInfo.Ancestor].Label;
+ if (DT.Info[VAncestorLabel].Semi >= DT.Info[VLabel].Semi)
+ return VLabel;
+ else
+ return VAncestorLabel;
+#endif
+}
+
+void DTLink(DominatorTree& DT, BasicBlock *V, BasicBlock *W,
+ DominatorTree::InfoRec &WInfo) {
+#if !BALANCE_IDOM_TREE
+ // Higher-complexity but faster implementation
+ WInfo.Ancestor = V;
+#else
+ // Lower-complexity but slower implementation
+ BasicBlock *WLabel = WInfo.Label;
+ unsigned WLabelSemi = Info[WLabel].Semi;
+ BasicBlock *S = W;
+ InfoRec *SInfo = &Info[S];
+
+ BasicBlock *SChild = SInfo->Child;
+ InfoRec *SChildInfo = &Info[SChild];
+
+ while (WLabelSemi < Info[SChildInfo->Label].Semi) {
+ BasicBlock *SChildChild = SChildInfo->Child;
+ if (SInfo->Size+Info[SChildChild].Size >= 2*SChildInfo->Size) {
+ SChildInfo->Ancestor = S;
+ SInfo->Child = SChild = SChildChild;
+ SChildInfo = &Info[SChild];
+ } else {
+ SChildInfo->Size = SInfo->Size;
+ S = SInfo->Ancestor = SChild;
+ SInfo = SChildInfo;
+ SChild = SChildChild;
+ SChildInfo = &Info[SChild];
+ }
+ }
+
+ InfoRec &VInfo = Info[V];
+ SInfo->Label = WLabel;
+
+ assert(V != W && "The optimization here will not work in this case!");
+ unsigned WSize = WInfo.Size;
+ unsigned VSize = (VInfo.Size += WSize);
+
+ if (VSize < 2*WSize)
+ std::swap(S, VInfo.Child);
+
+ while (S) {
+ SInfo = &Info[S];
+ SInfo->Ancestor = V;
+ S = SInfo->Child;
+ }
+#endif
+}
+
+void DTcalculate(DominatorTree& DT, Function &F) {
+ BasicBlock* Root = DT.Roots[0];
+
+ // Add a node for the root...
+ DT.DomTreeNodes[Root] = DT.RootNode = new DomTreeNode(Root, 0);
+
+ DT.Vertex.push_back(0);
+
+ // Step #1: Number blocks in depth-first order and initialize variables used
+ // in later stages of the algorithm.
+ unsigned N = DT.DFSPass(Root, 0);
+
+ for (unsigned i = N; i >= 2; --i) {
+ BasicBlock *W = DT.Vertex[i];
+ DominatorTree::InfoRec &WInfo = DT.Info[W];
+
+ // Step #2: Calculate the semidominators of all vertices
+ for (pred_iterator PI = pred_begin(W), E = pred_end(W); PI != E; ++PI)
+ if (DT.Info.count(*PI)) { // Only if this predecessor is reachable!
+ unsigned SemiU = DT.Info[DTEval(DT, *PI)].Semi;
+ if (SemiU < WInfo.Semi)
+ WInfo.Semi = SemiU;
+ }
+
+ DT.Info[DT.Vertex[WInfo.Semi]].Bucket.push_back(W);
+
+ BasicBlock *WParent = WInfo.Parent;
+ DTLink(DT, WParent, W, WInfo);
+
+ // Step #3: Implicitly define the immediate dominator of vertices
+ std::vector<BasicBlock*> &WParentBucket = DT.Info[WParent].Bucket;
+ while (!WParentBucket.empty()) {
+ BasicBlock *V = WParentBucket.back();
+ WParentBucket.pop_back();
+ BasicBlock *U = DTEval(DT, V);
+ DT.IDoms[V] = DT.Info[U].Semi < DT.Info[V].Semi ? U : WParent;
+ }
+ }
+
+ // Step #4: Explicitly define the immediate dominator of each vertex
+ for (unsigned i = 2; i <= N; ++i) {
+ BasicBlock *W = DT.Vertex[i];
+ BasicBlock *&WIDom = DT.IDoms[W];
+ if (WIDom != DT.Vertex[DT.Info[W].Semi])
+ WIDom = DT.IDoms[WIDom];
+ }
+
+ // Loop over all of the reachable blocks in the function...
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+ if (BasicBlock *ImmDom = DT.getIDom(I)) { // Reachable block.
+ DomTreeNode *BBNode = DT.DomTreeNodes[I];
+ if (BBNode) continue; // Haven't calculated this node yet?
+
+ // Get or calculate the node for the immediate dominator
+ DomTreeNode *IDomNode = DT.getNodeForBlock(ImmDom);
+
+ // Add a new tree node for this BasicBlock, and link it as a child of
+ // IDomNode
+ DomTreeNode *C = new DomTreeNode(I, IDomNode);
+ DT.DomTreeNodes[I] = IDomNode->addChild(C);
+ }
+
+ // Free temporary memory used to construct idom's
+ DT.Info.clear();
+ DT.IDoms.clear();
+ std::vector<BasicBlock*>().swap(DT.Vertex);
+
+ DT.updateDFSNumbers();
+}
+
+}
+#endif
\ No newline at end of file
#include "llvm/ADT/SmallVector.h"
#include "llvm/Instructions.h"
#include "llvm/Support/Streams.h"
+#include "DominatorCalculation.h"
#include <algorithm>
using namespace llvm;
// DominatorTree Implementation
//===----------------------------------------------------------------------===//
//
-// DominatorTree construction - This pass constructs immediate dominator
-// information for a flow-graph based on the algorithm described in this
-// document:
-//
-// A Fast Algorithm for Finding Dominators in a Flowgraph
-// T. Lengauer & R. Tarjan, ACM TOPLAS July 1979, pgs 121-141.
-//
-// This implements both the O(n*ack(n)) and the O(n*log(n)) versions of EVAL and
-// LINK, but it turns out that the theoretically slower O(n*log(n))
-// implementation is actually faster than the "efficient" algorithm (even for
-// large CFGs) because the constant overheads are substantially smaller. The
-// lower-complexity version can be enabled with the following #define:
-//
-#define BALANCE_IDOM_TREE 0
+// Provide public access to DominatorTree information. Implementation details
+// can be found in DominatorCalculation.h.
//
//===----------------------------------------------------------------------===//
static RegisterPass<DominatorTree>
E("domtree", "Dominator Tree Construction", true);
+unsigned DominatorTreeBase::DFSPass(BasicBlock *V, unsigned N) {
+ // This is more understandable as a recursive algorithm, but we can't use the
+ // recursive algorithm due to stack depth issues. Keep it here for
+ // documentation purposes.
+#if 0
+ InfoRec &VInfo = Info[Roots[i]];
+ VInfo.Semi = ++N;
+ VInfo.Label = V;
+
+ Vertex.push_back(V); // Vertex[n] = V;
+ //Info[V].Ancestor = 0; // Ancestor[n] = 0
+ //Info[V].Child = 0; // Child[v] = 0
+ VInfo.Size = 1; // Size[v] = 1
+
+ for (succ_iterator SI = succ_begin(V), E = succ_end(V); SI != E; ++SI) {
+ InfoRec &SuccVInfo = Info[*SI];
+ if (SuccVInfo.Semi == 0) {
+ SuccVInfo.Parent = V;
+ N = DFSPass(*SI, N);
+ }
+ }
+#else
+ std::vector<std::pair<BasicBlock*, unsigned> > Worklist;
+ Worklist.push_back(std::make_pair(V, 0U));
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.back().first;
+ unsigned NextSucc = Worklist.back().second;
+
+ // First time we visited this BB?
+ if (NextSucc == 0) {
+ InfoRec &BBInfo = Info[BB];
+ BBInfo.Semi = ++N;
+ BBInfo.Label = BB;
+
+ Vertex.push_back(BB); // Vertex[n] = V;
+ //BBInfo[V].Ancestor = 0; // Ancestor[n] = 0
+ //BBInfo[V].Child = 0; // Child[v] = 0
+ BBInfo.Size = 1; // Size[v] = 1
+ }
+
+ // If we are done with this block, remove it from the worklist.
+ if (NextSucc == BB->getTerminator()->getNumSuccessors()) {
+ Worklist.pop_back();
+ continue;
+ }
+
+ // Otherwise, increment the successor number for the next time we get to it.
+ ++Worklist.back().second;
+
+ // Visit the successor next, if it isn't already visited.
+ BasicBlock *Succ = BB->getTerminator()->getSuccessor(NextSucc);
+
+ InfoRec &SuccVInfo = Info[Succ];
+ if (SuccVInfo.Semi == 0) {
+ SuccVInfo.Parent = BB;
+ Worklist.push_back(std::make_pair(Succ, 0U));
+ }
+ }
+#endif
+ return N;
+}
+
// NewBB is split and now it has one successor. Update dominator tree to
// reflect this change.
void DominatorTree::splitBlock(BasicBlock *NewBB) {
}
}
-unsigned DominatorTree::DFSPass(BasicBlock *V, unsigned N) {
- // This is more understandable as a recursive algorithm, but we can't use the
- // recursive algorithm due to stack depth issues. Keep it here for
- // documentation purposes.
-#if 0
- InfoRec &VInfo = Info[Roots[i]];
- VInfo.Semi = ++N;
- VInfo.Label = V;
-
- Vertex.push_back(V); // Vertex[n] = V;
- //Info[V].Ancestor = 0; // Ancestor[n] = 0
- //Info[V].Child = 0; // Child[v] = 0
- VInfo.Size = 1; // Size[v] = 1
-
- for (succ_iterator SI = succ_begin(V), E = succ_end(V); SI != E; ++SI) {
- InfoRec &SuccVInfo = Info[*SI];
- if (SuccVInfo.Semi == 0) {
- SuccVInfo.Parent = V;
- N = DFSPass(*SI, N);
- }
- }
-#else
- std::vector<std::pair<BasicBlock*, unsigned> > Worklist;
- Worklist.push_back(std::make_pair(V, 0U));
- while (!Worklist.empty()) {
- BasicBlock *BB = Worklist.back().first;
- unsigned NextSucc = Worklist.back().second;
-
- // First time we visited this BB?
- if (NextSucc == 0) {
- InfoRec &BBInfo = Info[BB];
- BBInfo.Semi = ++N;
- BBInfo.Label = BB;
-
- Vertex.push_back(BB); // Vertex[n] = V;
- //BBInfo[V].Ancestor = 0; // Ancestor[n] = 0
- //BBInfo[V].Child = 0; // Child[v] = 0
- BBInfo.Size = 1; // Size[v] = 1
- }
-
- // If we are done with this block, remove it from the worklist.
- if (NextSucc == BB->getTerminator()->getNumSuccessors()) {
- Worklist.pop_back();
- continue;
- }
-
- // Otherwise, increment the successor number for the next time we get to it.
- ++Worklist.back().second;
-
- // Visit the successor next, if it isn't already visited.
- BasicBlock *Succ = BB->getTerminator()->getSuccessor(NextSucc);
-
- InfoRec &SuccVInfo = Info[Succ];
- if (SuccVInfo.Semi == 0) {
- SuccVInfo.Parent = BB;
- Worklist.push_back(std::make_pair(Succ, 0U));
- }
- }
-#endif
- return N;
-}
-
-void DominatorTree::Compress(BasicBlock *VIn) {
-
- std::vector<BasicBlock *> Work;
- SmallPtrSet<BasicBlock *, 32> Visited;
- BasicBlock *VInAncestor = Info[VIn].Ancestor;
- InfoRec &VInVAInfo = Info[VInAncestor];
-
- if (VInVAInfo.Ancestor != 0)
- Work.push_back(VIn);
-
- while (!Work.empty()) {
- BasicBlock *V = Work.back();
- InfoRec &VInfo = Info[V];
- BasicBlock *VAncestor = VInfo.Ancestor;
- InfoRec &VAInfo = Info[VAncestor];
-
- // Process Ancestor first
- if (Visited.insert(VAncestor) &&
- VAInfo.Ancestor != 0) {
- Work.push_back(VAncestor);
- continue;
- }
- Work.pop_back();
-
- // Update VInfo based on Ancestor info
- if (VAInfo.Ancestor == 0)
- continue;
- BasicBlock *VAncestorLabel = VAInfo.Label;
- BasicBlock *VLabel = VInfo.Label;
- if (Info[VAncestorLabel].Semi < Info[VLabel].Semi)
- VInfo.Label = VAncestorLabel;
- VInfo.Ancestor = VAInfo.Ancestor;
- }
-}
-
-BasicBlock *DominatorTree::Eval(BasicBlock *V) {
- InfoRec &VInfo = Info[V];
-#if !BALANCE_IDOM_TREE
- // Higher-complexity but faster implementation
- if (VInfo.Ancestor == 0)
- return V;
- Compress(V);
- return VInfo.Label;
-#else
- // Lower-complexity but slower implementation
- if (VInfo.Ancestor == 0)
- return VInfo.Label;
- Compress(V);
- BasicBlock *VLabel = VInfo.Label;
-
- BasicBlock *VAncestorLabel = Info[VInfo.Ancestor].Label;
- if (Info[VAncestorLabel].Semi >= Info[VLabel].Semi)
- return VLabel;
- else
- return VAncestorLabel;
-#endif
-}
-
-void DominatorTree::Link(BasicBlock *V, BasicBlock *W, InfoRec &WInfo){
-#if !BALANCE_IDOM_TREE
- // Higher-complexity but faster implementation
- WInfo.Ancestor = V;
-#else
- // Lower-complexity but slower implementation
- BasicBlock *WLabel = WInfo.Label;
- unsigned WLabelSemi = Info[WLabel].Semi;
- BasicBlock *S = W;
- InfoRec *SInfo = &Info[S];
-
- BasicBlock *SChild = SInfo->Child;
- InfoRec *SChildInfo = &Info[SChild];
-
- while (WLabelSemi < Info[SChildInfo->Label].Semi) {
- BasicBlock *SChildChild = SChildInfo->Child;
- if (SInfo->Size+Info[SChildChild].Size >= 2*SChildInfo->Size) {
- SChildInfo->Ancestor = S;
- SInfo->Child = SChild = SChildChild;
- SChildInfo = &Info[SChild];
- } else {
- SChildInfo->Size = SInfo->Size;
- S = SInfo->Ancestor = SChild;
- SInfo = SChildInfo;
- SChild = SChildChild;
- SChildInfo = &Info[SChild];
- }
- }
-
- InfoRec &VInfo = Info[V];
- SInfo->Label = WLabel;
-
- assert(V != W && "The optimization here will not work in this case!");
- unsigned WSize = WInfo.Size;
- unsigned VSize = (VInfo.Size += WSize);
-
- if (VSize < 2*WSize)
- std::swap(S, VInfo.Child);
-
- while (S) {
- SInfo = &Info[S];
- SInfo->Ancestor = V;
- S = SInfo->Child;
- }
-#endif
-}
-
-void DominatorTree::calculate(Function &F) {
- BasicBlock* Root = Roots[0];
-
- // Add a node for the root...
- DomTreeNodes[Root] = RootNode = new DomTreeNode(Root, 0);
-
- Vertex.push_back(0);
-
- // Step #1: Number blocks in depth-first order and initialize variables used
- // in later stages of the algorithm.
- unsigned N = DFSPass(Root, 0);
-
- for (unsigned i = N; i >= 2; --i) {
- BasicBlock *W = Vertex[i];
- InfoRec &WInfo = Info[W];
-
- // Step #2: Calculate the semidominators of all vertices
- for (pred_iterator PI = pred_begin(W), E = pred_end(W); PI != E; ++PI)
- if (Info.count(*PI)) { // Only if this predecessor is reachable!
- unsigned SemiU = Info[Eval(*PI)].Semi;
- if (SemiU < WInfo.Semi)
- WInfo.Semi = SemiU;
- }
-
- Info[Vertex[WInfo.Semi]].Bucket.push_back(W);
-
- BasicBlock *WParent = WInfo.Parent;
- Link(WParent, W, WInfo);
-
- // Step #3: Implicitly define the immediate dominator of vertices
- std::vector<BasicBlock*> &WParentBucket = Info[WParent].Bucket;
- while (!WParentBucket.empty()) {
- BasicBlock *V = WParentBucket.back();
- WParentBucket.pop_back();
- BasicBlock *U = Eval(V);
- IDoms[V] = Info[U].Semi < Info[V].Semi ? U : WParent;
- }
- }
-
- // Step #4: Explicitly define the immediate dominator of each vertex
- for (unsigned i = 2; i <= N; ++i) {
- BasicBlock *W = Vertex[i];
- BasicBlock *&WIDom = IDoms[W];
- if (WIDom != Vertex[Info[W].Semi])
- WIDom = IDoms[WIDom];
- }
-
- // Loop over all of the reachable blocks in the function...
- for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
- if (BasicBlock *ImmDom = getIDom(I)) { // Reachable block.
- DomTreeNode *BBNode = DomTreeNodes[I];
- if (BBNode) continue; // Haven't calculated this node yet?
-
- // Get or calculate the node for the immediate dominator
- DomTreeNode *IDomNode = getNodeForBlock(ImmDom);
-
- // Add a new tree node for this BasicBlock, and link it as a child of
- // IDomNode
- DomTreeNode *C = new DomTreeNode(I, IDomNode);
- DomTreeNodes[I] = IDomNode->addChild(C);
- }
-
- // Free temporary memory used to construct idom's
- Info.clear();
- IDoms.clear();
- std::vector<BasicBlock*>().swap(Vertex);
-
- updateDFSNumbers();
-}
-
void DominatorTreeBase::updateDFSNumbers() {
unsigned DFSNum = 0;
RootNode = 0;
}
+DomTreeNode *DominatorTreeBase::getNodeForBlock(BasicBlock *BB) {
+ if (DomTreeNode *BBNode = DomTreeNodes[BB])
+ return BBNode;
+
+ // Haven't calculated this node yet? Get or calculate the node for the
+ // immediate dominator.
+ BasicBlock *IDom = getIDom(BB);
+ DomTreeNode *IDomNode = getNodeForBlock(IDom);
+
+ // Add a new tree node for this BasicBlock, and link it as a child of
+ // IDomNode
+ DomTreeNode *C = new DomTreeNode(BB, IDomNode);
+ return DomTreeNodes[BB] = IDomNode->addChild(C);
+}
+
/// findNearestCommonDominator - Find nearest common dominator basic block
/// for basic block A and B. If there is no such block then return NULL.
BasicBlock *DominatorTreeBase::findNearestCommonDominator(BasicBlock *A,
}
}
-DomTreeNode *DominatorTree::getNodeForBlock(BasicBlock *BB) {
- if (DomTreeNode *BBNode = DomTreeNodes[BB])
- return BBNode;
-
- // Haven't calculated this node yet? Get or calculate the node for the
- // immediate dominator.
- BasicBlock *IDom = getIDom(BB);
- DomTreeNode *IDomNode = getNodeForBlock(IDom);
-
- // Add a new tree node for this BasicBlock, and link it as a child of
- // IDomNode
- DomTreeNode *C = new DomTreeNode(BB, IDomNode);
- return DomTreeNodes[BB] = IDomNode->addChild(C);
-}
-
static std::ostream &operator<<(std::ostream &o, const DomTreeNode *Node) {
if (Node->getBlock())
WriteAsOperand(o, Node->getBlock(), false);
bool DominatorTree::runOnFunction(Function &F) {
reset(); // Reset from the last time we were run...
Roots.push_back(&F.getEntryBlock());
- calculate(F);
+ DTcalculate(*this, F);
return false;
}
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