forked from OSchip/llvm-project
422 lines
15 KiB
C++
422 lines
15 KiB
C++
//===- DataStructure.cpp - Implement the core data structure analysis -----===//
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//
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// This file implements the core data structure functionality.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Module.h"
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#include "llvm/DerivedTypes.h"
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#include "Support/STLExtras.h"
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#include "Support/StatisticReporter.h"
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#include "Support/STLExtras.h"
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#include <algorithm>
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#include <set>
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#include "llvm/Analysis/DataStructure.h"
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using std::vector;
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AnalysisID LocalDataStructures::ID(AnalysisID::create<LocalDataStructures>());
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//===----------------------------------------------------------------------===//
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// DSNode Implementation
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//===----------------------------------------------------------------------===//
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DSNode::DSNode(enum NodeTy NT, const Type *T) : Ty(T), NodeType(NT) {
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// If this node has any fields, allocate them now, but leave them null.
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switch (T->getPrimitiveID()) {
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case Type::PointerTyID: Links.resize(1); break;
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case Type::ArrayTyID: Links.resize(1); break;
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case Type::StructTyID:
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Links.resize(cast<StructType>(T)->getNumContainedTypes());
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break;
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default: break;
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}
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}
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// DSNode copy constructor... do not copy over the referrers list!
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DSNode::DSNode(const DSNode &N)
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: Ty(N.Ty), Links(N.Links), Globals(N.Globals), NodeType(N.NodeType) {
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}
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void DSNode::removeReferrer(DSNodeHandle *H) {
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// Search backwards, because we depopulate the list from the back for
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// efficiency (because it's a vector).
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vector<DSNodeHandle*>::reverse_iterator I =
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std::find(Referrers.rbegin(), Referrers.rend(), H);
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assert(I != Referrers.rend() && "Referrer not pointing to node!");
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Referrers.erase(I.base()-1);
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}
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// addGlobal - Add an entry for a global value to the Globals list. This also
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// marks the node with the 'G' flag if it does not already have it.
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//
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void DSNode::addGlobal(GlobalValue *GV) {
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// Keep the list sorted.
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vector<GlobalValue*>::iterator I =
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std::lower_bound(Globals.begin(), Globals.end(), GV);
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if (I == Globals.end() || *I != GV) {
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assert(GV->getType()->getElementType() == Ty);
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Globals.insert(I, GV);
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NodeType |= GlobalNode;
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}
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}
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// addEdgeTo - Add an edge from the current node to the specified node. This
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// can cause merging of nodes in the graph.
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//
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void DSNode::addEdgeTo(unsigned LinkNo, DSNode *N) {
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assert(LinkNo < Links.size() && "LinkNo out of range!");
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if (N == 0 || Links[LinkNo] == N) return; // Nothing to do
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if (Links[LinkNo] == 0) { // No merging to perform
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Links[LinkNo] = N;
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return;
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}
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// Merge the two nodes...
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Links[LinkNo]->mergeWith(N);
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}
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// mergeWith - Merge this node into the specified node, moving all links to and
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// from the argument node into the current node. The specified node may be a
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// null pointer (in which case, nothing happens).
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//
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void DSNode::mergeWith(DSNode *N) {
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if (N == 0 || N == this) return; // Noop
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assert(N->Ty == Ty && N->Links.size() == Links.size() &&
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"Cannot merge nodes of two different types!");
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// Remove all edges pointing at N, causing them to point to 'this' instead.
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while (!N->Referrers.empty())
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*N->Referrers.back() = this;
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// Make all of the outgoing links of N now be outgoing links of this. This
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// can cause recursive merging!
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//
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for (unsigned i = 0, e = Links.size(); i != e; ++i) {
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addEdgeTo(i, N->Links[i]);
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N->Links[i] = 0; // Reduce unneccesary edges in graph. N is dead
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}
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// Merge the node types
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NodeType |= N->NodeType;
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N->NodeType = 0; // N is now a dead node.
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// Merge the globals list...
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if (!N->Globals.empty()) {
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// Save the current globals off to the side...
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vector<GlobalValue*> OldGlobals(Globals);
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// Resize the globals vector to be big enough to hold both of them...
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Globals.resize(Globals.size()+N->Globals.size());
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// Merge the two sorted globals lists together...
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std::merge(OldGlobals.begin(), OldGlobals.end(),
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N->Globals.begin(), N->Globals.end(), Globals.begin());
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// Erase duplicate entries from the globals list...
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Globals.erase(std::unique(Globals.begin(), Globals.end()), Globals.end());
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// Delete the globals from the old node...
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N->Globals.clear();
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}
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}
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//===----------------------------------------------------------------------===//
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// DSGraph Implementation
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//===----------------------------------------------------------------------===//
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DSGraph::DSGraph(const DSGraph &G) : Func(G.Func) {
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std::map<const DSNode*, DSNode*> NodeMap; // ignored
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RetNode = cloneInto(G, ValueMap, NodeMap, false);
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}
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DSGraph::~DSGraph() {
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FunctionCalls.clear();
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OrigFunctionCalls.clear();
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ValueMap.clear();
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RetNode = 0;
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#ifndef NDEBUG
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// Drop all intra-node references, so that assertions don't fail...
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std::for_each(Nodes.begin(), Nodes.end(),
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std::mem_fun(&DSNode::dropAllReferences));
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#endif
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// Delete all of the nodes themselves...
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std::for_each(Nodes.begin(), Nodes.end(), deleter<DSNode>);
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}
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// dump - Allow inspection of graph in a debugger.
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void DSGraph::dump() const { print(std::cerr); }
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// cloneInto - Clone the specified DSGraph into the current graph, returning the
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// Return node of the graph. The translated ValueMap for the old function is
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// filled into the OldValMap member. If StripLocals is set to true, Scalar and
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// Alloca markers are removed from the graph, as the graph is being cloned into
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// a calling function's graph.
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//
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DSNode *DSGraph::cloneInto(const DSGraph &G,
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std::map<Value*, DSNodeHandle> &OldValMap,
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std::map<const DSNode*, DSNode*> &OldNodeMap,
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bool StripLocals) {
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assert(OldNodeMap.size()==0 && "Return argument OldNodeMap should be empty");
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OldNodeMap[0] = 0; // Null pointer maps to null
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unsigned FN = Nodes.size(); // FirstNode...
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// Duplicate all of the nodes, populating the node map...
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Nodes.reserve(FN+G.Nodes.size());
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for (unsigned i = 0, e = G.Nodes.size(); i != e; ++i) {
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DSNode *Old = G.Nodes[i], *New = new DSNode(*Old);
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Nodes.push_back(New);
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OldNodeMap[Old] = New;
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}
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// Rewrite the links in the nodes to point into the current graph now.
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for (unsigned i = FN, e = Nodes.size(); i != e; ++i)
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for (unsigned j = 0, e = Nodes[i]->getNumLinks(); j != e; ++j)
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Nodes[i]->setLink(j, OldNodeMap[Nodes[i]->getLink(j)]);
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// If we are inlining this graph into the called function graph, remove local
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// markers.
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if (StripLocals)
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for (unsigned i = FN, e = Nodes.size(); i != e; ++i)
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Nodes[i]->NodeType &= ~(DSNode::AllocaNode | DSNode::ScalarNode);
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// Copy the value map...
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for (std::map<Value*, DSNodeHandle>::const_iterator I = G.ValueMap.begin(),
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E = G.ValueMap.end(); I != E; ++I)
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OldValMap[I->first] = OldNodeMap[I->second];
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// Copy the function calls list...
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unsigned FC = FunctionCalls.size(); // FirstCall
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FunctionCalls.reserve(FC+G.FunctionCalls.size());
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for (unsigned i = 0, e = G.FunctionCalls.size(); i != e; ++i) {
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FunctionCalls.push_back(std::vector<DSNodeHandle>());
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FunctionCalls[FC+i].reserve(G.FunctionCalls[i].size());
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for (unsigned j = 0, e = G.FunctionCalls[i].size(); j != e; ++j)
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FunctionCalls[FC+i].push_back(OldNodeMap[G.FunctionCalls[i][j]]);
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}
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// Copy the list of unresolved callers
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PendingCallers.insert(PendingCallers.end(),
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G.PendingCallers.begin(), G.PendingCallers.end());
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// Return the returned node pointer...
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return OldNodeMap[G.RetNode];
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}
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// markIncompleteNodes - Mark the specified node as having contents that are not
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// known with the current analysis we have performed. Because a node makes all
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// of the nodes it can reach imcomplete if the node itself is incomplete, we
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// must recursively traverse the data structure graph, marking all reachable
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// nodes as incomplete.
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//
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static void markIncompleteNode(DSNode *N) {
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// Stop recursion if no node, or if node already marked...
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if (N == 0 || (N->NodeType & DSNode::Incomplete)) return;
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// Actually mark the node
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N->NodeType |= DSNode::Incomplete;
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// Recusively process children...
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for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
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markIncompleteNode(N->getLink(i));
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}
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// markIncompleteNodes - Traverse the graph, identifying nodes that may be
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// modified by other functions that have not been resolved yet. This marks
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// nodes that are reachable through three sources of "unknownness":
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//
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// Global Variables, Function Calls, and Incoming Arguments
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//
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// For any node that may have unknown components (because something outside the
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// scope of current analysis may have modified it), the 'Incomplete' flag is
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// added to the NodeType.
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//
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void DSGraph::markIncompleteNodes() {
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// Mark any incoming arguments as incomplete...
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for (Function::aiterator I = Func.abegin(), E = Func.aend(); I != E; ++I)
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if (isa<PointerType>(I->getType()))
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markIncompleteNode(ValueMap[I]->getLink(0));
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// Mark stuff passed into functions calls as being incomplete...
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for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i) {
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vector<DSNodeHandle> &Args = FunctionCalls[i];
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// Then the return value is certainly incomplete!
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markIncompleteNode(Args[0]);
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// The call does not make the function argument incomplete...
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// All arguments to the function call are incomplete though!
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for (unsigned i = 2, e = Args.size(); i != e; ++i)
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markIncompleteNode(Args[i]);
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}
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// Mark all of the nodes pointed to by global or cast nodes as incomplete...
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for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
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if (Nodes[i]->NodeType & (DSNode::GlobalNode | DSNode::CastNode)) {
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DSNode *N = Nodes[i];
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for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
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markIncompleteNode(N->getLink(i));
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}
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}
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// isNodeDead - This method checks to see if a node is dead, and if it isn't, it
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// checks to see if there are simple transformations that it can do to make it
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// dead.
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//
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bool DSGraph::isNodeDead(DSNode *N) {
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// Is it a trivially dead shadow node...
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if (N->getReferrers().empty() && N->NodeType == 0)
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return true;
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// Is it a function node or some other trivially unused global?
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if ((N->NodeType & ~DSNode::GlobalNode) == 0 &&
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N->getNumLinks() == 0 &&
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N->getReferrers().size() == N->getGlobals().size()) {
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// Remove the globals from the valuemap, so that the referrer count will go
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// down to zero.
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while (!N->getGlobals().empty()) {
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GlobalValue *GV = N->getGlobals().back();
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N->getGlobals().pop_back();
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ValueMap.erase(GV);
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}
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assert(N->getReferrers().empty() && "Referrers should all be gone now!");
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return true;
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}
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return false;
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}
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// removeTriviallyDeadNodes - After the graph has been constructed, this method
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// removes all unreachable nodes that are created because they got merged with
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// other nodes in the graph. These nodes will all be trivially unreachable, so
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// we don't have to perform any non-trivial analysis here.
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//
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void DSGraph::removeTriviallyDeadNodes() {
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for (unsigned i = 0; i != Nodes.size(); ++i)
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if (isNodeDead(Nodes[i])) { // This node is dead!
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delete Nodes[i]; // Free memory...
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Nodes.erase(Nodes.begin()+i--); // Remove from node list...
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}
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// Remove trivially identical function calls
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unsigned NumFns = FunctionCalls.size();
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std::sort(FunctionCalls.begin(), FunctionCalls.end());
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FunctionCalls.erase(std::unique(FunctionCalls.begin(), FunctionCalls.end()),
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FunctionCalls.end());
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DEBUG(if (NumFns != FunctionCalls.size())
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std::cerr << "Merged " << (NumFns-FunctionCalls.size())
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<< " call nodes in " << Func.getName() << "\n";);
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}
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// markAlive - Simple graph traverser that recursively walks the graph marking
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// stuff to be alive.
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//
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static void markAlive(DSNode *N, std::set<DSNode*> &Alive) {
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if (N == 0 || Alive.count(N)) return;
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Alive.insert(N);
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for (unsigned i = 0, e = N->getNumLinks(); i != e; ++i)
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markAlive(N->getLink(i), Alive);
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}
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// removeDeadNodes - Use a more powerful reachability analysis to eliminate
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// subgraphs that are unreachable. This often occurs because the data
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// structure doesn't "escape" into it's caller, and thus should be eliminated
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// from the caller's graph entirely. This is only appropriate to use when
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// inlining graphs.
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//
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void DSGraph::removeDeadNodes() {
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// Reduce the amount of work we have to do...
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removeTriviallyDeadNodes();
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// FIXME: Merge nontrivially identical call nodes...
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// Alive - a set that holds all nodes found to be reachable/alive.
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std::set<DSNode*> Alive;
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// Mark all nodes reachable by call nodes as alive...
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for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i)
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for (unsigned j = 0, e = FunctionCalls[i].size(); j != e; ++j)
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markAlive(FunctionCalls[i][j], Alive);
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for (unsigned i = 0, e = OrigFunctionCalls.size(); i != e; ++i)
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for (unsigned j = 0, e = OrigFunctionCalls[i].size(); j != e; ++j)
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markAlive(OrigFunctionCalls[i][j], Alive);
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// Mark all nodes reachable by scalar, global, or incomplete nodes as
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// reachable...
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for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
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if (Nodes[i]->NodeType & (DSNode::ScalarNode | DSNode::GlobalNode))
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markAlive(Nodes[i], Alive);
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// Loop over all unreachable nodes, dropping their references...
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std::vector<DSNode*> DeadNodes;
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DeadNodes.reserve(Nodes.size()); // Only one allocation is allowed.
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for (unsigned i = 0; i != Nodes.size(); ++i)
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if (!Alive.count(Nodes[i])) {
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DSNode *N = Nodes[i];
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Nodes.erase(Nodes.begin()+i--); // Erase node from alive list.
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DeadNodes.push_back(N); // Add node to our list of dead nodes
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N->dropAllReferences(); // Drop all outgoing edges
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}
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// The return value is alive as well...
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markAlive(RetNode, Alive);
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// Delete all dead nodes...
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std::for_each(DeadNodes.begin(), DeadNodes.end(), deleter<DSNode>);
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}
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// maskNodeTypes - Apply a mask to all of the node types in the graph. This
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// is useful for clearing out markers like Scalar or Incomplete.
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//
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void DSGraph::maskNodeTypes(unsigned char Mask) {
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for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
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Nodes[i]->NodeType &= Mask;
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}
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//===----------------------------------------------------------------------===//
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// LocalDataStructures Implementation
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//===----------------------------------------------------------------------===//
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// releaseMemory - If the pass pipeline is done with this pass, we can release
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// our memory... here...
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//
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void LocalDataStructures::releaseMemory() {
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for (std::map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
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E = DSInfo.end(); I != E; ++I)
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delete I->second;
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// Empty map so next time memory is released, data structures are not
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// re-deleted.
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DSInfo.clear();
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}
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bool LocalDataStructures::run(Module &M) {
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// Calculate all of the graphs...
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
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if (!I->isExternal())
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DSInfo.insert(std::make_pair(&*I, new DSGraph(*I)));
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return false;
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}
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