llvm-6502/lib/Analysis/DataStructure/DataStructure.cpp
Vikram S. Adve 6aa0d62cb9 Add support for a top-down propagation pass.
Each DSGraph now keeps a list of pending callers that have not
been inlined into the function represented by that graph.
It also keeps a copy of the original call nodes before the BU pass
eliminates some of them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2965 91177308-0d34-0410-b5e6-96231b3b80d8
2002-07-18 16:12:08 +00:00

369 lines
13 KiB
C++

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