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Major repairs to the post-dominators implementation. Patch from Florian Brandner!

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@49768 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2008-04-16 04:21:16 +00:00
parent 036a94ed61
commit 1f23e16319
4 changed files with 113 additions and 40 deletions
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100
include/llvm/Analysis/DominatorInternals.h
View File

@ -42,7 +42,7 @@ unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
// documentation purposes.
#if 0
InfoRec &VInfo = DT.Info[DT.Roots[i]];
VInfo.Semi = ++N;
VInfo.DFSNum = VInfo.Semi = ++N;
VInfo.Label = V;
Vertex.push_back(V); // Vertex[n] = V;
@ -58,6 +58,8 @@ unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
}
}
#else
bool IsChilOfArtificialExit = (N != 0);
std::vector<std::pair<typename GraphT::NodeType*,
typename GraphT::ChildIteratorType> > Worklist;
Worklist.push_back(std::make_pair(V, GraphT::child_begin(V)));
@ -65,19 +67,29 @@ unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType* BB = Worklist.back().first;
typename GraphT::ChildIteratorType NextSucc = Worklist.back().second;
// First time we visited this BB?
if (NextSucc == GraphT::child_begin(BB)) {
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &BBInfo =
DT.Info[BB];
BBInfo.Semi = ++N;
// First time we visited this BB?
if (NextSucc == GraphT::child_begin(BB)) {
BBInfo.DFSNum = BBInfo.Semi = ++N;
BBInfo.Label = BB;
DT.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 (IsChilOfArtificialExit)
BBInfo.Parent = 1;
IsChilOfArtificialExit = false;
}
// store the DFS number of the current BB - the reference to BBInfo might
// get invalidated when processing the successors.
unsigned BBDFSNum = BBInfo.DFSNum;
// If we are done with this block, remove it from the worklist.
if (NextSucc == GraphT::child_end(BB)) {
Worklist.pop_back();
@ -93,7 +105,7 @@ unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &SuccVInfo =
DT.Info[Succ];
if (SuccVInfo.Semi == 0) {
SuccVInfo.Parent = BB;
SuccVInfo.Parent = BBDFSNum;
Worklist.push_back(std::make_pair(Succ, GraphT::child_begin(Succ)));
}
}
@ -106,9 +118,8 @@ void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType *VIn) {
std::vector<typename GraphT::NodeType*> Work;
SmallPtrSet<typename GraphT::NodeType*, 32> Visited;
typename GraphT::NodeType* VInAncestor = DT.Info[VIn].Ancestor;
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VInVAInfo =
DT.Info[VInAncestor];
DT.Info[DT.Vertex[DT.Info[VIn].Ancestor]];
if (VInVAInfo.Ancestor != 0)
Work.push_back(VIn);
@ -117,7 +128,7 @@ void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType* V = Work.back();
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VInfo =
DT.Info[V];
typename GraphT::NodeType* VAncestor = VInfo.Ancestor;
typename GraphT::NodeType* VAncestor = DT.Vertex[VInfo.Ancestor];
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VAInfo =
DT.Info[VAncestor];
@ -168,11 +179,11 @@ typename GraphT::NodeType* Eval(DominatorTreeBase<typename GraphT::NodeType>& DT
template<class GraphT>
void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType* V, typename GraphT::NodeType* W,
unsigned DFSNumV, typename GraphT::NodeType* W,
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo) {
#if !BALANCE_IDOM_TREE
// Higher-complexity but faster implementation
WInfo.Ancestor = V;
WInfo.Ancestor = DFSNumV;
#else
// Lower-complexity but slower implementation
GraphT::NodeType* WLabel = WInfo.Label;
@ -221,9 +232,29 @@ void Calculate(DominatorTreeBase<typename GraphTraits<NodeT>::NodeType>& DT,
FuncT& F) {
typedef GraphTraits<NodeT> GraphT;
unsigned N = 0;
// 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.
typename GraphT::NodeType* Root = DT.Roots.size() == 1 ? DT.Roots[0]
: 0;
bool MultipleRoots = (DT.Roots.size() > 1);
if (MultipleRoots) {
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &BBInfo =
DT.Info[NULL];
BBInfo.DFSNum = BBInfo.Semi = ++N;
BBInfo.Label = NULL;
DT.Vertex.push_back(NULL); // Vertex[n] = V;
//BBInfo[V].Ancestor = 0; // Ancestor[n] = 0
//BBInfo[V].Child = 0; // Child[v] = 0
BBInfo.Size = 1; // Size[v] = 1
}
// 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 = DT.Roots.size(); i != e; ++i)
N = DFSPass<GraphT>(DT, DT.Roots[i], N);
@ -233,19 +264,34 @@ void Calculate(DominatorTreeBase<typename GraphTraits<NodeT>::NodeType>& DT,
DT.Info[W];
// Step #2: Calculate the semidominators of all vertices
bool HasChildOutsideDFS = false;
// initialize the semi dominator to point to the parent node
WInfo.Semi = WInfo.Parent;
for (typename GraphTraits<Inverse<NodeT> >::ChildIteratorType CI =
GraphTraits<Inverse<NodeT> >::child_begin(W),
E = GraphTraits<Inverse<NodeT> >::child_end(W); CI != E; ++CI)
E = GraphTraits<Inverse<NodeT> >::child_end(W); CI != E; ++CI) {
if (DT.Info.count(*CI)) { // Only if this predecessor is reachable!
unsigned SemiU = DT.Info[Eval<GraphT>(DT, *CI)].Semi;
if (SemiU < WInfo.Semi)
WInfo.Semi = SemiU;
}
else {
// if the child has no DFS number it is not post-dominated by any exit,
// and so is the current block.
HasChildOutsideDFS = true;
}
}
// if some child has no DFS number it is not post-dominated by any exit,
// and so is the current block.
if (DT.isPostDominator() && HasChildOutsideDFS)
WInfo.Semi = 0;
DT.Info[DT.Vertex[WInfo.Semi]].Bucket.push_back(W);
typename GraphT::NodeType* WParent = WInfo.Parent;
Link<GraphT>(DT, WParent, W, WInfo);
typename GraphT::NodeType* WParent = DT.Vertex[WInfo.Parent];
Link<GraphT>(DT, WInfo.Parent, W, WInfo);
// Step #3: Implicitly define the immediate dominator of vertices
std::vector<typename GraphT::NodeType*> &WParentBucket =
@ -271,27 +317,37 @@ void Calculate(DominatorTreeBase<typename GraphTraits<NodeT>::NodeType>& DT,
// 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.
typename GraphT::NodeType* Root = DT.Roots.size() == 1 ? DT.Roots[0]
: 0;
DT.DomTreeNodes[Root] = DT.RootNode =
new DomTreeNodeBase<typename GraphT::NodeType>(Root, 0);
// Loop over all of the reachable blocks in the function...
for (typename FuncT::iterator I = F.begin(), E = F.end(); I != E; ++I)
if (typename GraphT::NodeType* ImmDom = DT.getIDom(I)) {
// Reachable block.
DomTreeNodeBase<typename GraphT::NodeType> *BBNode = DT.DomTreeNodes[I];
for (unsigned i = 2; i <= N; ++i) {
typename GraphT::NodeType* W = DT.Vertex[i];
DomTreeNodeBase<typename GraphT::NodeType> *BBNode = DT.DomTreeNodes[W];
if (BBNode) continue; // Haven't calculated this node yet?
typename GraphT::NodeType* ImmDom = DT.getIDom(W);
// skip all non root nodes that have no dominator - this occures with
// infinite loops.
if (!ImmDom && std::count(DT.Roots.begin(), DT.Roots.end(), W) == 0)
continue;
// Get or calculate the node for the immediate dominator
DomTreeNodeBase<typename GraphT::NodeType> *IDomNode =
DT.getNodeForBlock(ImmDom);
// skip all children that are dominated by a non root node that, by itself,
// has no dominator.
if (!IDomNode)
continue;
// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
DomTreeNodeBase<typename GraphT::NodeType> *C =
new DomTreeNodeBase<typename GraphT::NodeType>(I, IDomNode);
DT.DomTreeNodes[I] = IDomNode->addChild(C);
new DomTreeNodeBase<typename GraphT::NodeType>(W, IDomNode);
DT.DomTreeNodes[W] = IDomNode->addChild(C);
}
// Free temporary memory used to construct idom's

22
include/llvm/Analysis/Dominators.h
View File

@ -182,13 +182,16 @@ protected:
unsigned int SlowQueries;
// Information record used during immediate dominators computation.
struct InfoRec {
unsigned DFSNum;
unsigned Semi;
unsigned Size;
NodeT *Label, *Parent, *Child, *Ancestor;
NodeT *Label, *Child;
unsigned Parent, Ancestor;
std::vector<NodeT*> Bucket;
InfoRec() : Semi(0), Size(0), Label(0), Parent(0), Child(0), Ancestor(0) {}
InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0),
Ancestor(0) {}
};
DenseMap<NodeT*, NodeT*> IDoms;
@ -544,8 +547,7 @@ protected:
template<class GraphT>
friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
typename GraphT::NodeType* V,
typename GraphT::NodeType* W,
unsigned DFSNumV, typename GraphT::NodeType* W,
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo);
template<class GraphT>
@ -602,8 +604,18 @@ protected:
// Haven't calculated this node yet? Get or calculate the node for the
// immediate dominator.
NodeT *IDom = getIDom(BB);
// skip all non root nodes that have no dominator
if (!IDom && std::count(this->Roots.begin(), this->Roots.end(), BB) == 0)
return NULL;
DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
// skip all nodes that are dominated by a non root node that, by itself,
// has no dominator.
if (!IDomNode)
return NULL;
// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode);
@ -616,8 +628,6 @@ protected:
}
inline void addRoot(NodeT* BB) {
// Unreachable block is not a root node.
if (!isa<UnreachableInst>(&BB->back()))
this->Roots.push_back(BB);
}

4
lib/Analysis/PostDominators.cpp
View File

@ -11,9 +11,12 @@
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "postdomtree"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/Instructions.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/Analysis/DominatorInternals.h"
@ -30,6 +33,7 @@ F("postdomtree", "Post-Dominator Tree Construction", true, true);
bool PostDominatorTree::runOnFunction(Function &F) {
DT->recalculate(F);
DEBUG(DT->dump());
return false;
}

5
lib/VMCore/Dominators.cpp
View File

@ -14,9 +14,12 @@
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "domtree"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/SmallPtrSet.h"
@ -58,7 +61,7 @@ E("domtree", "Dominator Tree Construction", true, true);
bool DominatorTree::runOnFunction(Function &F) {
DT->recalculate(F);
DEBUG(DT->dump());
return false;
}