mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-30 21:29:28 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61715 91177308-0d34-0410-b5e6-96231b3b80d8
364 lines
13 KiB
C++
364 lines
13 KiB
C++
//=== llvm/Analysis/DominatorInternals.h - Dominator Calculation -*- C++ -*-==//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_ANALYSIS_DOMINATOR_INTERNALS_H
|
|
#define LLVM_ANALYSIS_DOMINATOR_INTERNALS_H
|
|
|
|
#include "llvm/Analysis/Dominators.h"
|
|
#include "llvm/ADT/SmallPtrSet.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 {
|
|
|
|
template<class GraphT>
|
|
unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
|
|
typename GraphT::NodeType* 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 = DT.Info[DT.Roots[i]];
|
|
VInfo.DFSNum = 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 = DT.Info[*SI];
|
|
if (SuccVInfo.Semi == 0) {
|
|
SuccVInfo.Parent = V;
|
|
N = DTDFSPass(DT, *SI, N);
|
|
}
|
|
}
|
|
#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)));
|
|
while (!Worklist.empty()) {
|
|
typename GraphT::NodeType* BB = Worklist.back().first;
|
|
typename GraphT::ChildIteratorType NextSucc = Worklist.back().second;
|
|
|
|
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &BBInfo =
|
|
DT.Info[BB];
|
|
|
|
// 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();
|
|
continue;
|
|
}
|
|
|
|
// 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.
|
|
typename GraphT::NodeType* Succ = *NextSucc;
|
|
|
|
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &SuccVInfo =
|
|
DT.Info[Succ];
|
|
if (SuccVInfo.Semi == 0) {
|
|
SuccVInfo.Parent = BBDFSNum;
|
|
Worklist.push_back(std::make_pair(Succ, GraphT::child_begin(Succ)));
|
|
}
|
|
}
|
|
#endif
|
|
return N;
|
|
}
|
|
|
|
template<class GraphT>
|
|
void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
|
|
typename GraphT::NodeType *VIn) {
|
|
std::vector<typename GraphT::NodeType*> Work;
|
|
SmallPtrSet<typename GraphT::NodeType*, 32> Visited;
|
|
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VInVAInfo =
|
|
DT.Info[DT.Vertex[DT.Info[VIn].Ancestor]];
|
|
|
|
if (VInVAInfo.Ancestor != 0)
|
|
Work.push_back(VIn);
|
|
|
|
while (!Work.empty()) {
|
|
typename GraphT::NodeType* V = Work.back();
|
|
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VInfo =
|
|
DT.Info[V];
|
|
typename GraphT::NodeType* VAncestor = DT.Vertex[VInfo.Ancestor];
|
|
typename DominatorTreeBase<typename GraphT::NodeType>::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;
|
|
typename GraphT::NodeType* VAncestorLabel = VAInfo.Label;
|
|
typename GraphT::NodeType* VLabel = VInfo.Label;
|
|
if (DT.Info[VAncestorLabel].Semi < DT.Info[VLabel].Semi)
|
|
VInfo.Label = VAncestorLabel;
|
|
VInfo.Ancestor = VAInfo.Ancestor;
|
|
}
|
|
}
|
|
|
|
template<class GraphT>
|
|
typename GraphT::NodeType* Eval(DominatorTreeBase<typename GraphT::NodeType>& DT,
|
|
typename GraphT::NodeType *V) {
|
|
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VInfo =
|
|
DT.Info[V];
|
|
#if !BALANCE_IDOM_TREE
|
|
// Higher-complexity but faster implementation
|
|
if (VInfo.Ancestor == 0)
|
|
return V;
|
|
Compress<GraphT>(DT, V);
|
|
return VInfo.Label;
|
|
#else
|
|
// Lower-complexity but slower implementation
|
|
if (VInfo.Ancestor == 0)
|
|
return VInfo.Label;
|
|
Compress<GraphT>(DT, V);
|
|
GraphT::NodeType* VLabel = VInfo.Label;
|
|
|
|
GraphT::NodeType* VAncestorLabel = DT.Info[VInfo.Ancestor].Label;
|
|
if (DT.Info[VAncestorLabel].Semi >= DT.Info[VLabel].Semi)
|
|
return VLabel;
|
|
else
|
|
return VAncestorLabel;
|
|
#endif
|
|
}
|
|
|
|
template<class GraphT>
|
|
void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
|
|
unsigned DFSNumV, typename GraphT::NodeType* W,
|
|
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo) {
|
|
#if !BALANCE_IDOM_TREE
|
|
// Higher-complexity but faster implementation
|
|
WInfo.Ancestor = DFSNumV;
|
|
#else
|
|
// Lower-complexity but slower implementation
|
|
GraphT::NodeType* WLabel = WInfo.Label;
|
|
unsigned WLabelSemi = DT.Info[WLabel].Semi;
|
|
GraphT::NodeType* S = W;
|
|
InfoRec *SInfo = &DT.Info[S];
|
|
|
|
GraphT::NodeType* SChild = SInfo->Child;
|
|
InfoRec *SChildInfo = &DT.Info[SChild];
|
|
|
|
while (WLabelSemi < DT.Info[SChildInfo->Label].Semi) {
|
|
GraphT::NodeType* SChildChild = SChildInfo->Child;
|
|
if (SInfo->Size+DT.Info[SChildChild].Size >= 2*SChildInfo->Size) {
|
|
SChildInfo->Ancestor = S;
|
|
SInfo->Child = SChild = SChildChild;
|
|
SChildInfo = &DT.Info[SChild];
|
|
} else {
|
|
SChildInfo->Size = SInfo->Size;
|
|
S = SInfo->Ancestor = SChild;
|
|
SInfo = SChildInfo;
|
|
SChild = SChildChild;
|
|
SChildInfo = &DT.Info[SChild];
|
|
}
|
|
}
|
|
|
|
DominatorTreeBase::InfoRec &VInfo = DT.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 = &DT.Info[S];
|
|
SInfo->Ancestor = V;
|
|
S = SInfo->Child;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
template<class FuncT, class NodeT>
|
|
void Calculate(DominatorTreeBase<typename GraphTraits<NodeT>::NodeType>& DT,
|
|
FuncT& F) {
|
|
typedef GraphTraits<NodeT> GraphT;
|
|
|
|
unsigned N = 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.
|
|
for (unsigned i = 0, e = static_cast<unsigned>(DT.Roots.size());
|
|
i != e; ++i)
|
|
N = DFSPass<GraphT>(DT, DT.Roots[i], N);
|
|
|
|
// it might be that some blocks did not get a DFS number (e.g., blocks of
|
|
// infinite loops). In these cases an artificial exit node is required.
|
|
MultipleRoots |= (DT.isPostDominator() && N != F.size());
|
|
|
|
for (unsigned i = N; i >= 2; --i) {
|
|
typename GraphT::NodeType* W = DT.Vertex[i];
|
|
typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo =
|
|
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) {
|
|
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 = 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 =
|
|
DT.Info[WParent].Bucket;
|
|
while (!WParentBucket.empty()) {
|
|
typename GraphT::NodeType* V = WParentBucket.back();
|
|
WParentBucket.pop_back();
|
|
typename GraphT::NodeType* U = Eval<GraphT>(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) {
|
|
typename GraphT::NodeType* W = DT.Vertex[i];
|
|
typename GraphT::NodeType*& WIDom = DT.IDoms[W];
|
|
if (WIDom != DT.Vertex[DT.Info[W].Semi])
|
|
WIDom = DT.IDoms[WIDom];
|
|
}
|
|
|
|
if (DT.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, or
|
|
// an infinite loop.
|
|
typename GraphT::NodeType* Root = !MultipleRoots ? 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 (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);
|
|
|
|
assert(ImmDom || DT.DomTreeNodes[NULL]);
|
|
|
|
// Get or calculate the node for the immediate dominator
|
|
DomTreeNodeBase<typename GraphT::NodeType> *IDomNode =
|
|
DT.getNodeForBlock(ImmDom);
|
|
|
|
// 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>(W, IDomNode);
|
|
DT.DomTreeNodes[W] = IDomNode->addChild(C);
|
|
}
|
|
|
|
// Free temporary memory used to construct idom's
|
|
DT.IDoms.clear();
|
|
DT.Info.clear();
|
|
std::vector<typename GraphT::NodeType*>().swap(DT.Vertex);
|
|
|
|
// FIXME: This does not work on PostDomTrees. It seems likely that this is
|
|
// due to an error in the algorithm for post-dominators. This really should
|
|
// be investigated and fixed at some point.
|
|
// DT.updateDFSNumbers();
|
|
|
|
// Start out with the DFS numbers being invalid. Let them be computed if
|
|
// demanded.
|
|
DT.DFSInfoValid = false;
|
|
}
|
|
|
|
}
|
|
|
|
#endif
|