mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-17 05:29:24 +00:00
Fix PR681 by using the standard Lengauer and Tarjan algorithm for dominator
set construction, rather than intersecting various std::sets. This reduces the memory usage for the testcase in PR681 from 496 to 26MB of ram on my darwin system, and reduces the runtime from 32.8 to 0.8 seconds on a 2.5GHz G5. This also enables future code sharing between Dom and PostDom now that they share near-identical implementations. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26707 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
parent
78167faa18
commit
442b32b5c5
@ -18,6 +18,42 @@
|
||||
|
||||
namespace llvm {
|
||||
|
||||
//===-------------------------------------
|
||||
/// ImmediatePostDominators Class - Concrete subclass of ImmediateDominatorsBase
|
||||
/// that is used to compute a normal immediate dominator set.
|
||||
///
|
||||
struct ImmediatePostDominators : public ImmediateDominatorsBase {
|
||||
ImmediatePostDominators() : ImmediateDominatorsBase(false) {}
|
||||
|
||||
virtual bool runOnFunction(Function &F);
|
||||
|
||||
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
||||
AU.setPreservesAll();
|
||||
}
|
||||
|
||||
private:
|
||||
struct InfoRec {
|
||||
unsigned Semi;
|
||||
unsigned Size;
|
||||
BasicBlock *Label, *Parent, *Child, *Ancestor;
|
||||
|
||||
std::vector<BasicBlock*> Bucket;
|
||||
|
||||
InfoRec() : Semi(0), Size(0), Label(0), Parent(0), Child(0), Ancestor(0){}
|
||||
};
|
||||
|
||||
// Vertex - Map the DFS number to the BasicBlock*
|
||||
std::vector<BasicBlock*> Vertex;
|
||||
|
||||
// Info - Collection of information used during the computation of idoms.
|
||||
std::map<BasicBlock*, InfoRec> Info;
|
||||
|
||||
unsigned DFSPass(BasicBlock *V, InfoRec &VInfo, unsigned N);
|
||||
void Compress(BasicBlock *V, InfoRec &VInfo);
|
||||
BasicBlock *Eval(BasicBlock *v);
|
||||
void Link(BasicBlock *V, BasicBlock *W, InfoRec &WInfo);
|
||||
};
|
||||
|
||||
/// PostDominatorSet Class - Concrete subclass of DominatorSetBase that is used
|
||||
/// to compute the post-dominator set. Because there can be multiple exit nodes
|
||||
/// in an LLVM function, we calculate post dominators with a special null block
|
||||
@ -27,40 +63,20 @@ namespace llvm {
|
||||
///
|
||||
struct PostDominatorSet : public DominatorSetBase {
|
||||
PostDominatorSet() : DominatorSetBase(true) {}
|
||||
|
||||
|
||||
virtual bool runOnFunction(Function &F);
|
||||
|
||||
/// getAnalysisUsage - This pass does not modify the function at all.
|
||||
|
||||
/// getAnalysisUsage - This simply provides a dominator set
|
||||
///
|
||||
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
||||
AU.addRequired<ImmediatePostDominators>();
|
||||
AU.setPreservesAll();
|
||||
}
|
||||
|
||||
// stub - dummy function, just ignore it
|
||||
static void stub();
|
||||
};
|
||||
|
||||
|
||||
/// ImmediatePostDominators Class - Concrete subclass of ImmediateDominatorsBase
|
||||
/// that is used to compute the immediate post-dominators.
|
||||
///
|
||||
struct ImmediatePostDominators : public ImmediateDominatorsBase {
|
||||
ImmediatePostDominators() : ImmediateDominatorsBase(true) {}
|
||||
|
||||
virtual bool runOnFunction(Function &F) {
|
||||
IDoms.clear(); // Reset from the last time we were run...
|
||||
PostDominatorSet &DS = getAnalysis<PostDominatorSet>();
|
||||
Roots = DS.getRoots();
|
||||
calcIDoms(DS);
|
||||
return false;
|
||||
}
|
||||
|
||||
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
||||
AU.setPreservesAll();
|
||||
AU.addRequired<PostDominatorSet>();
|
||||
}
|
||||
private:
|
||||
void calcIDoms(const DominatorSetBase &DS);
|
||||
};
|
||||
|
||||
|
||||
/// PostDominatorTree Class - Concrete subclass of DominatorTree that is used to
|
||||
/// compute the a post-dominator tree.
|
||||
///
|
||||
@ -69,18 +85,19 @@ struct PostDominatorTree : public DominatorTreeBase {
|
||||
|
||||
virtual bool runOnFunction(Function &F) {
|
||||
reset(); // Reset from the last time we were run...
|
||||
PostDominatorSet &DS = getAnalysis<PostDominatorSet>();
|
||||
Roots = DS.getRoots();
|
||||
calculate(DS);
|
||||
ImmediatePostDominators &IPD = getAnalysis<ImmediatePostDominators>();
|
||||
Roots = IPD.getRoots();
|
||||
calculate(IPD);
|
||||
return false;
|
||||
}
|
||||
|
||||
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
||||
AU.setPreservesAll();
|
||||
AU.addRequired<PostDominatorSet>();
|
||||
AU.addRequired<ImmediatePostDominators>();
|
||||
}
|
||||
private:
|
||||
void calculate(const PostDominatorSet &DS);
|
||||
void calculate(const ImmediatePostDominators &IPD);
|
||||
Node *getNodeForBlock(BasicBlock *BB);
|
||||
};
|
||||
|
||||
|
||||
|
@ -16,8 +16,131 @@
|
||||
#include "llvm/Support/CFG.h"
|
||||
#include "llvm/ADT/DepthFirstIterator.h"
|
||||
#include "llvm/ADT/SetOperations.h"
|
||||
#include <iostream>
|
||||
using namespace llvm;
|
||||
|
||||
//===----------------------------------------------------------------------===//
|
||||
// ImmediatePostDominators Implementation
|
||||
//===----------------------------------------------------------------------===//
|
||||
|
||||
static RegisterAnalysis<ImmediatePostDominators>
|
||||
D("postidom", "Immediate Post-Dominators Construction", true);
|
||||
|
||||
unsigned ImmediatePostDominators::DFSPass(BasicBlock *V, InfoRec &VInfo,
|
||||
unsigned N) {
|
||||
VInfo.Semi = ++N;
|
||||
VInfo.Label = V;
|
||||
|
||||
Vertex.push_back(V); // Vertex[n] = V;
|
||||
//Info[V].Ancestor = 0; // Ancestor[n] = 0
|
||||
//Child[V] = 0; // Child[v] = 0
|
||||
VInfo.Size = 1; // Size[v] = 1
|
||||
|
||||
// For PostDominators, we want to walk predecessors rather than successors
|
||||
// as we do in forward Dominators.
|
||||
for (pred_iterator PI = pred_begin(V), PE = pred_end(V); PI != PE; ++PI) {
|
||||
InfoRec &SuccVInfo = Info[*PI];
|
||||
if (SuccVInfo.Semi == 0) {
|
||||
SuccVInfo.Parent = V;
|
||||
N = DFSPass(*PI, SuccVInfo, N);
|
||||
}
|
||||
}
|
||||
return N;
|
||||
}
|
||||
|
||||
void ImmediatePostDominators::Compress(BasicBlock *V, InfoRec &VInfo) {
|
||||
BasicBlock *VAncestor = VInfo.Ancestor;
|
||||
InfoRec &VAInfo = Info[VAncestor];
|
||||
if (VAInfo.Ancestor == 0)
|
||||
return;
|
||||
|
||||
Compress(VAncestor, VAInfo);
|
||||
|
||||
BasicBlock *VAncestorLabel = VAInfo.Label;
|
||||
BasicBlock *VLabel = VInfo.Label;
|
||||
if (Info[VAncestorLabel].Semi < Info[VLabel].Semi)
|
||||
VInfo.Label = VAncestorLabel;
|
||||
|
||||
VInfo.Ancestor = VAInfo.Ancestor;
|
||||
}
|
||||
|
||||
BasicBlock *ImmediatePostDominators::Eval(BasicBlock *V) {
|
||||
InfoRec &VInfo = Info[V];
|
||||
|
||||
// Higher-complexity but faster implementation
|
||||
if (VInfo.Ancestor == 0)
|
||||
return V;
|
||||
Compress(V, VInfo);
|
||||
return VInfo.Label;
|
||||
}
|
||||
|
||||
void ImmediatePostDominators::Link(BasicBlock *V, BasicBlock *W,
|
||||
InfoRec &WInfo) {
|
||||
// Higher-complexity but faster implementation
|
||||
WInfo.Ancestor = V;
|
||||
}
|
||||
|
||||
bool ImmediatePostDominators::runOnFunction(Function &F) {
|
||||
IDoms.clear(); // Reset from the last time we were run...
|
||||
Roots.clear();
|
||||
|
||||
// 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)
|
||||
if (succ_begin(I) == succ_end(I))
|
||||
Roots.push_back(I);
|
||||
|
||||
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 = Roots.size(); i != e; ++i)
|
||||
N = DFSPass(Roots[i], Info[Roots[i]], N);
|
||||
|
||||
for (unsigned i = N; i >= 2; --i) {
|
||||
BasicBlock *W = Vertex[i];
|
||||
InfoRec &WInfo = 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 (Info.count(*SI)) { // Only if this predecessor is reachable!
|
||||
unsigned SemiU = Info[Eval(*SI)].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];
|
||||
}
|
||||
|
||||
// Free temporary memory used to construct idom's
|
||||
Info.clear();
|
||||
std::vector<BasicBlock*>().swap(Vertex);
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
//===----------------------------------------------------------------------===//
|
||||
// PostDominatorSet Implementation
|
||||
//===----------------------------------------------------------------------===//
|
||||
@ -30,119 +153,59 @@ B("postdomset", "Post-Dominator Set Construction", true);
|
||||
// sets for the function.
|
||||
//
|
||||
bool PostDominatorSet::runOnFunction(Function &F) {
|
||||
Doms.clear(); // Reset from the last time we were run...
|
||||
|
||||
// Scan the function looking for the root nodes of the post-dominance
|
||||
// relationships. These blocks end with return and unwind instructions.
|
||||
// While we are iterating over the function, we also initialize all of the
|
||||
// domsets to empty.
|
||||
Roots.clear();
|
||||
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
|
||||
Doms[I]; // Initialize to empty
|
||||
|
||||
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
|
||||
if (succ_begin(I) == succ_end(I))
|
||||
Roots.push_back(I);
|
||||
}
|
||||
|
||||
// If there are no exit nodes for the function, postdomsets are all empty.
|
||||
// This can happen if the function just contains an infinite loop, for
|
||||
// example.
|
||||
ImmediatePostDominators &IPD = getAnalysis<ImmediatePostDominators>();
|
||||
Doms.clear(); // Reset from the last time we were run...
|
||||
if (Roots.empty()) return false;
|
||||
|
||||
// If we have more than one root, we insert an artificial "null" exit, which
|
||||
// has "virtual edges" to each of the real exit nodes.
|
||||
if (Roots.size() > 1)
|
||||
Doms[0].insert(0);
|
||||
//if (Roots.size() > 1)
|
||||
// Doms[0].insert(0);
|
||||
|
||||
bool Changed;
|
||||
do {
|
||||
Changed = false;
|
||||
// Root nodes only dominate themselves.
|
||||
for (unsigned i = 0, e = Roots.size(); i != e; ++i)
|
||||
Doms[Roots[i]].insert(Roots[i]);
|
||||
|
||||
// Loop over all of the blocks in the function, calculating dominator sets for
|
||||
// each function.
|
||||
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
|
||||
if (BasicBlock *IPDom = IPD[I]) { // Get idom if block is reachable
|
||||
DomSetType &DS = Doms[I];
|
||||
assert(DS.empty() && "PostDomset already filled in for this block?");
|
||||
DS.insert(I); // Blocks always dominate themselves
|
||||
|
||||
std::set<BasicBlock*> Visited;
|
||||
DomSetType WorkingSet;
|
||||
|
||||
for (unsigned i = 0, e = Roots.size(); i != e; ++i)
|
||||
for (idf_ext_iterator<BasicBlock*> It = idf_ext_begin(Roots[i], Visited),
|
||||
E = idf_ext_end(Roots[i], Visited); It != E; ++It) {
|
||||
BasicBlock *BB = *It;
|
||||
succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
|
||||
if (SI != SE) { // Is there SOME successor?
|
||||
// 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[*SI].size() == 0) ++SI;
|
||||
WorkingSet = Doms[*SI];
|
||||
|
||||
for (++SI; SI != SE; ++SI) { // Intersect all of the successor sets
|
||||
DomSetType &SuccSet = Doms[*SI];
|
||||
if (SuccSet.size())
|
||||
set_intersect(WorkingSet, SuccSet);
|
||||
}
|
||||
// Insert all dominators into the set...
|
||||
while (IPDom) {
|
||||
// If we have already computed the dominator sets for our immediate post
|
||||
// dominator, just use it instead of walking all the way up to the root.
|
||||
DomSetType &IPDS = Doms[IPDom];
|
||||
if (!IPDS.empty()) {
|
||||
DS.insert(IPDS.begin(), IPDS.end());
|
||||
break;
|
||||
} else {
|
||||
// If this node has no successors, it must be one of the root nodes.
|
||||
// We will already take care of the notion that the node
|
||||
// post-dominates itself. The only thing we have to add is that if
|
||||
// there are multiple root nodes, we want to insert a special "null"
|
||||
// exit node which dominates the roots as well.
|
||||
if (Roots.size() > 1)
|
||||
WorkingSet.insert(0);
|
||||
DS.insert(IPDom);
|
||||
IPDom = IPD[IPDom];
|
||||
}
|
||||
|
||||
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;
|
||||
}
|
||||
|
||||
//===----------------------------------------------------------------------===//
|
||||
// ImmediatePostDominators Implementation
|
||||
//===----------------------------------------------------------------------===//
|
||||
|
||||
static RegisterAnalysis<ImmediatePostDominators>
|
||||
D("postidom", "Immediate Post-Dominators Construction", true);
|
||||
|
||||
|
||||
// calcIDoms - Calculate the immediate dominator mapping, given a set of
|
||||
// dominators for every basic block.
|
||||
void ImmediatePostDominators::calcIDoms(const DominatorSetBase &DS) {
|
||||
// Loop over all of the nodes that have dominators... figuring out the IDOM
|
||||
// for each node...
|
||||
//
|
||||
for (DominatorSet::const_iterator DI = DS.begin(), DEnd = DS.end();
|
||||
DI != DEnd; ++DI) {
|
||||
BasicBlock *BB = DI->first;
|
||||
const DominatorSet::DomSetType &Dominators = DI->second;
|
||||
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!
|
||||
//
|
||||
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) {
|
||||
IDoms[BB] = *I;
|
||||
break;
|
||||
}
|
||||
} else {
|
||||
// Ensure that every basic block has at least an empty set of nodes. This
|
||||
// is important for the case when there is unreachable blocks.
|
||||
Doms[I];
|
||||
}
|
||||
}
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
//===----------------------------------------------------------------------===//
|
||||
@ -152,59 +215,45 @@ void ImmediatePostDominators::calcIDoms(const DominatorSetBase &DS) {
|
||||
static RegisterAnalysis<PostDominatorTree>
|
||||
F("postdomtree", "Post-Dominator Tree Construction", true);
|
||||
|
||||
void PostDominatorTree::calculate(const PostDominatorSet &DS) {
|
||||
DominatorTreeBase::Node *PostDominatorTree::getNodeForBlock(BasicBlock *BB) {
|
||||
Node *&BBNode = Nodes[BB];
|
||||
if (BBNode) return BBNode;
|
||||
|
||||
// Haven't calculated this node yet? Get or calculate the node for the
|
||||
// immediate postdominator.
|
||||
BasicBlock *IPDom = getAnalysis<ImmediatePostDominators>()[BB];
|
||||
Node *IPDomNode = getNodeForBlock(IPDom);
|
||||
|
||||
// Add a new tree node for this BasicBlock, and link it as a child of
|
||||
// IDomNode
|
||||
return BBNode = IPDomNode->addChild(new Node(BB, IPDomNode));
|
||||
}
|
||||
|
||||
void PostDominatorTree::calculate(const ImmediatePostDominators &IPD) {
|
||||
if (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 = Roots.size() == 1 ? Roots[0] : 0;
|
||||
|
||||
Nodes[Root] = RootNode = new Node(Root, 0); // Add a node for the root...
|
||||
|
||||
// Iterate over all nodes in depth first order...
|
||||
for (unsigned i = 0, e = Roots.size(); i != e; ++i)
|
||||
for (idf_iterator<BasicBlock*> I = idf_begin(Roots[i]),
|
||||
E = idf_end(Roots[i]); 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
|
||||
|
||||
// If we have already computed the immediate dominator for this node,
|
||||
// don't revisit. This can happen due to nodes reachable from multiple
|
||||
// roots, but which the idf_iterator doesn't know about.
|
||||
if (Nodes.find(BB) != Nodes.end()) continue;
|
||||
|
||||
// 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.
|
||||
//
|
||||
for (DominatorSet::DomSetType::const_iterator I = Dominators.begin(),
|
||||
E = Dominators.end(); I != E; ++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;
|
||||
}
|
||||
Nodes[Root] = RootNode = new Node(Root, 0);
|
||||
|
||||
Function *F = Roots[0]->getParent();
|
||||
// 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 = IPD.get(I)) { // Reachable block.
|
||||
Node *&BBNode = Nodes[I];
|
||||
if (!BBNode) { // Haven't calculated this node yet?
|
||||
// Get or calculate the node for the immediate dominator
|
||||
Node *IPDomNode = getNodeForBlock(ImmPostDom);
|
||||
|
||||
// Add a new tree node for this BasicBlock, and link it as a child of
|
||||
// IDomNode
|
||||
BBNode = IPDomNode->addChild(new Node(I, IPDomNode));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
//===----------------------------------------------------------------------===//
|
||||
// PostETForest Implementation
|
||||
//===----------------------------------------------------------------------===//
|
||||
|
Loading…
Reference in New Issue
Block a user