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Implement 2 important changes: (1) rematerialization from the globals graph,

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and (2) faster inlining by cloning only reachable nodes.  In particular:
(1) Added DSGraph::cloneReachableSubgraph and DSGraph::cloneReachableNodes
    to clone the subgraph reachable from a set of root nodes, into the
    current graph, merging the global nodes into thos in the current graph.
    The TD pass now uses this for faster inlining, and so does the
    next function.
(2) Added DSGraph::updateFromGlobalGraph() to rematerialize nodes from the
    globals graph into the current graph in both BU and TD passes.
(3) `I' flags are removed from all nodes in the globals graph, because they
    are difficult to maintain correctly and are not needed anyway.
(4) Aux. function calls are only removed to the globals graph if they
    will never be resovled.  (This is what fixed gap.)  The immediate
    reason is that if we took these out of a function (and moved them to
    the globals graph) we would need to rematerialize these nodes into the
    function graph for every function in the BU pass.  The longer term
    problem is that we would need to find a way to remove them from the
    globals graph iff they have been resolved on all paths through the
    call graph.

llvm-svn: 7187
This commit is contained in:
Vikram S. Adve 2003-07-16 21:36:31 +00:00
parent 0ce80bfa82
commit d1a85b7860
1 changed files with 249 additions and 64 deletions
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313
lib/Analysis/DataStructure/DataStructure.cpp
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@ -737,17 +737,20 @@ DSGraph::DSGraph(const DSGraph &G) : GlobalsGraph(0) {
PrintAuxCalls = false;
NodeMapTy NodeMap;
cloneInto(G, ScalarMap, ReturnNodes, NodeMap);
InlinedGlobals.clear(); // clear set of "up-to-date" globals
}
DSGraph::DSGraph(const DSGraph &G, NodeMapTy &NodeMap)
: GlobalsGraph(0) {
PrintAuxCalls = false;
cloneInto(G, ScalarMap, ReturnNodes, NodeMap);
InlinedGlobals.clear(); // clear set of "up-to-date" globals
}
DSGraph::~DSGraph() {
FunctionCalls.clear();
AuxFunctionCalls.clear();
InlinedGlobals.clear();
ScalarMap.clear();
ReturnNodes.clear();
@ -775,6 +778,126 @@ void DSNode::remapLinks(DSGraph::NodeMapTy &OldNodeMap) {
}
/// cloneReachableNodes - Clone all reachable nodes from *Node into the
/// current graph. This is a recursive function. The map OldNodeMap is a
/// map from the original nodes to their clones.
///
void DSGraph::cloneReachableNodes(const DSNode* Node,
unsigned BitsToClear,
NodeMapTy& OldNodeMap,
NodeMapTy& CompletedNodeMap) {
if (CompletedNodeMap.find(Node) != CompletedNodeMap.end())
return;
DSNodeHandle& NH = OldNodeMap[Node];
if (NH.getNode() != NULL)
return;
// else Node has not yet been cloned: clone it and clear the specified bits
NH = new DSNode(*Node, this); // enters in OldNodeMap
NH.getNode()->maskNodeTypes(~BitsToClear);
// now recursively clone nodes pointed to by this node
for (unsigned i = 0, e = Node->getNumLinks(); i != e; ++i) {
const DSNodeHandle &Link = Node->getLink(i << DS::PointerShift);
if (const DSNode* nextNode = Link.getNode())
cloneReachableNodes(nextNode, BitsToClear, OldNodeMap, CompletedNodeMap);
}
}
void DSGraph::cloneReachableSubgraph(const DSGraph& G,
const hash_set<const DSNode*>& RootNodes,
NodeMapTy& OldNodeMap,
NodeMapTy& CompletedNodeMap,
unsigned CloneFlags) {
if (RootNodes.empty())
return;
assert(OldNodeMap.empty() && "Returned OldNodeMap should be empty!");
assert(&G != this && "Cannot clone graph into itself!");
assert((*RootNodes.begin())->getParentGraph() == &G &&
"Root nodes do not belong to this graph!");
// Remove alloca or mod/ref bits as specified...
unsigned BitsToClear = ((CloneFlags & StripAllocaBit)? DSNode::AllocaNode : 0)
| ((CloneFlags & StripModRefBits)? (DSNode::Modified | DSNode::Read) : 0)
| ((CloneFlags & StripIncompleteBit)? DSNode::Incomplete : 0);
BitsToClear |= DSNode::DEAD; // Clear dead flag...
// Clone all nodes reachable from each root node, using a recursive helper
for (hash_set<const DSNode*>::const_iterator I = RootNodes.begin(),
E = RootNodes.end(); I != E; ++I)
cloneReachableNodes(*I, BitsToClear, OldNodeMap, CompletedNodeMap);
// Merge the map entries in OldNodeMap and CompletedNodeMap to remap links
NodeMapTy MergedMap(OldNodeMap);
MergedMap.insert(CompletedNodeMap.begin(), CompletedNodeMap.end());
// Rewrite the links in the newly created nodes (the nodes in OldNodeMap)
// to point into the current graph. MergedMap gives the full mapping.
for (NodeMapTy::iterator I=OldNodeMap.begin(), E=OldNodeMap.end(); I!= E; ++I)
I->second.getNode()->remapLinks(MergedMap);
// Now merge cloned global nodes with their copies in the current graph
// Just look through OldNodeMap to find such nodes!
for (NodeMapTy::iterator I=OldNodeMap.begin(), E=OldNodeMap.end(); I!= E; ++I)
if (I->first->isGlobalNode()) {
DSNodeHandle &GClone = I->second;
assert(GClone.getNode() != NULL && "NULL node in OldNodeMap?");
const std::vector<GlobalValue*> &Globals = I->first->getGlobals();
for (unsigned gi = 0, ge = Globals.size(); gi != ge; ++gi) {
DSNodeHandle &GH = ScalarMap[Globals[gi]];
GH.mergeWith(GClone);
}
}
}
/// updateFromGlobalGraph - This function rematerializes global nodes and
/// nodes reachable from them from the globals graph into the current graph.
/// It invokes cloneReachableSubgraph, using the globals in the current graph
/// as the roots. It also uses the vector InlinedGlobals to avoid cloning and
/// merging globals that are already up-to-date in the current graph. In
/// practice, in the TD pass, this is likely to be a large fraction of the
/// live global nodes in each function (since most live nodes are likely to
/// have been brought up-to-date in at _some_ caller or callee).
///
void DSGraph::updateFromGlobalGraph() {
// Use a map to keep track of the mapping between nodes in the globals graph
// and this graph for up-to-date global nodes, which do not need to be cloned.
NodeMapTy CompletedMap;
// Put the live, non-up-to-date global nodes into a set and the up-to-date
// ones in the map above, mapping node in GlobalsGraph to the up-to-date node.
hash_set<const DSNode*> GlobalNodeSet;
for (ScalarMapTy::const_iterator I = getScalarMap().begin(),
E = getScalarMap().end(); I != E; ++I)
if (GlobalValue* GV = dyn_cast<GlobalValue>(I->first)) {
DSNode* GNode = I->second.getNode();
assert(GNode && "No node for live global in current Graph?");
if (const DSNode* GGNode = GlobalsGraph->ScalarMap[GV].getNode())
if (InlinedGlobals.count(GV) == 0) // GNode is not up-to-date
GlobalNodeSet.insert(GGNode);
else { // GNode is up-to-date
CompletedMap[GGNode] = I->second;
assert(GGNode->getNumLinks() == GNode->getNumLinks() &&
"Links dont match in a node that is supposed to be up-to-date?"
"\nremapLinks() will not work if the links don't match!");
}
}
// Clone the subgraph reachable from the vector of nodes in GlobalNodes
// and merge the cloned global nodes with the corresponding ones, if any.
NodeMapTy OldNodeMap;
cloneReachableSubgraph(*GlobalsGraph, GlobalNodeSet, OldNodeMap,CompletedMap);
// Merging global nodes leaves behind unused nodes: get rid of them now.
OldNodeMap.clear(); // remove references before dead node cleanup
CompletedMap.clear(); // remove references before dead node cleanup
removeTriviallyDeadNodes();
}
/// cloneInto - Clone the specified DSGraph into the current graph. The
/// translated ScalarMap for the old function is filled into the OldValMap
/// member, and the translated ReturnNodes map is returned into ReturnNodes.
@ -793,8 +916,9 @@ void DSGraph::cloneInto(const DSGraph &G, ScalarMapTy &OldValMap,
Nodes.reserve(FN+G.Nodes.size());
// Remove alloca or mod/ref bits as specified...
unsigned BitsToClear =((CloneFlags & StripAllocaBit) ? DSNode::AllocaNode : 0)
| ((CloneFlags & StripModRefBits) ? (DSNode::Modified | DSNode::Read) : 0);
unsigned BitsToClear = ((CloneFlags & StripAllocaBit)? DSNode::AllocaNode : 0)
| ((CloneFlags & StripModRefBits)? (DSNode::Modified | DSNode::Read) : 0)
| ((CloneFlags & StripIncompleteBit)? DSNode::Incomplete : 0);
BitsToClear |= DSNode::DEAD; // Clear dead flag...
for (unsigned i = 0, e = G.Nodes.size(); i != e; ++i) {
DSNode *Old = G.Nodes[i];
@ -820,8 +944,10 @@ void DSGraph::cloneInto(const DSGraph &G, ScalarMapTy &OldValMap,
I->second.getOffset()+MappedNode.getOffset()));
// If this is a global, add the global to this fn or merge if already exists
if (isa<GlobalValue>(I->first))
ScalarMap[I->first].mergeWith(H);
if (GlobalValue* GV = dyn_cast<GlobalValue>(I->first)) {
ScalarMap[GV].mergeWith(H);
InlinedGlobals.insert(GV);
}
}
if (!(CloneFlags & DontCloneCallNodes)) {
@ -1101,8 +1227,16 @@ void DSGraph::removeTriviallyDeadNodes() {
removeIdenticalCalls(FunctionCalls);
removeIdenticalCalls(AuxFunctionCalls);
bool isGlobalsGraph = !GlobalsGraph;
for (unsigned i = 0; i != Nodes.size(); ++i) {
DSNode *Node = Nodes[i];
// Do not remove *any* global nodes in the globals graph.
// This is a special case because such nodes may not have I, M, R flags set.
if (Node->isGlobalNode() && isGlobalsGraph)
continue;
if (Node->isComplete() && !Node->isModified() && !Node->isRead()) {
// This is a useless node if it has no mod/ref info (checked above),
// outgoing edges (which it cannot, as it is not modified in this
@ -1127,6 +1261,32 @@ void DSGraph::removeTriviallyDeadNodes() {
Node->makeNodeDead();
}
}
#ifdef SANER_CODE_FOR_CHECKING_IF_ALL_REFERRERS_ARE_FROM_SCALARMAP
//
// *** It seems to me that we should be able to simply check if
// *** there are fewer or equal #referrers as #globals and make
// *** sure that all those referrers are in the scalar map?
//
if (Node->getNumReferrers() <= Node->getGlobals().size()) {
const std::vector<GlobalValue*> &Globals = Node->getGlobals();
#ifndef NDEBUG
// Loop through and make sure all of the globals are referring directly
// to the node...
for (unsigned j = 0, e = Globals.size(); j != e; ++j) {
DSNode *N = ScalarMap.find(Globals[j])->second.getNode();
assert(N == Node && "ScalarMap doesn't match globals list!");
}
#endif
// Make sure NumReferrers still agrees. The node is truly dead.
assert(Node->getNumReferrers() == Globals.size());
for (unsigned j = 0, e = Globals.size(); j != e; ++j)
ScalarMap.erase(Globals[j]);
Node->makeNodeDead();
}
#endif
}
if (Node->getNodeFlags() == 0 && Node->hasNoReferrers()) {
@ -1235,6 +1395,7 @@ void DSGraph::removeDeadNodes(unsigned Flags) {
for (ScalarMapTy::iterator I = ScalarMap.begin(), E = ScalarMap.end(); I !=E;)
if (isa<GlobalValue>(I->first)) { // Keep track of global nodes
assert(I->second.getNode() && "Null global node?");
assert(I->second.getNode()->isGlobalNode() && "Should be a global node!");
GlobalNodes.push_back(std::make_pair(I->first, I->second.getNode()));
++I;
} else {
@ -1266,6 +1427,18 @@ void DSGraph::removeDeadNodes(unsigned Flags) {
for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i)
FunctionCalls[i].markReachableNodes(Alive);
// Copy and merge all information about globals to the GlobalsGraph
// if this is not a final pass (where unreachable globals are removed)
NodeMapTy GlobalNodeMap;
hash_set<const DSNode*> GlobalNodeSet;
for (std::vector<std::pair<Value*, DSNode*> >::const_iterator
I = GlobalNodes.begin(), E = GlobalNodes.end(); I != E; ++I)
GlobalNodeSet.insert(I->second); // put global nodes into a set
// Now find globals and aux call nodes that are already live or reach a live
// value (which makes them live in turn), and continue till no more are found.
//
bool Iterate;
hash_set<DSNode*> Visited;
std::vector<unsigned char> AuxFCallsAlive(AuxFunctionCalls.size());
@ -1276,40 +1449,86 @@ void DSGraph::removeDeadNodes(unsigned Flags) {
// unreachable globals in the list.
//
Iterate = false;
for (unsigned i = 0; i != GlobalNodes.size(); ++i)
if (CanReachAliveNodes(GlobalNodes[i].second, Alive, Visited,
Flags & DSGraph::RemoveUnreachableGlobals)) {
std::swap(GlobalNodes[i--], GlobalNodes.back()); // Move to end to erase
GlobalNodes.pop_back(); // Erase efficiently
Iterate = true;
}
if (!(Flags & DSGraph::RemoveUnreachableGlobals))
for (unsigned i = 0; i != GlobalNodes.size(); ++i)
if (CanReachAliveNodes(GlobalNodes[i].second, Alive, Visited,
Flags & DSGraph::RemoveUnreachableGlobals)) {
std::swap(GlobalNodes[i--], GlobalNodes.back()); // Move to end to...
GlobalNodes.pop_back(); // erase efficiently
Iterate = true;
}
// Mark only unresolvable call nodes for moving to the GlobalsGraph since
// call nodes that get resolved will be difficult to remove from that graph.
// The final unresolved call nodes must be handled specially at the end of
// the BU pass (i.e., in main or other roots of the call graph).
for (unsigned i = 0, e = AuxFunctionCalls.size(); i != e; ++i)
if (!AuxFCallsAlive[i] &&
CallSiteUsesAliveArgs(AuxFunctionCalls[i], Alive, Visited,
Flags & DSGraph::RemoveUnreachableGlobals)) {
(AuxFunctionCalls[i].isIndirectCall()
|| CallSiteUsesAliveArgs(AuxFunctionCalls[i], Alive, Visited,
Flags & DSGraph::RemoveUnreachableGlobals))) {
AuxFunctionCalls[i].markReachableNodes(Alive);
AuxFCallsAlive[i] = true;
Iterate = true;
}
} while (Iterate);
// Remove all dead aux function calls...
// Move dead aux function calls to the end of the list
unsigned CurIdx = 0;
for (unsigned i = 0, e = AuxFunctionCalls.size(); i != e; ++i)
if (AuxFCallsAlive[i])
AuxFunctionCalls[CurIdx++].swap(AuxFunctionCalls[i]);
// Copy and merge all global nodes and dead aux call nodes into the
// GlobalsGraph, and all nodes reachable from those nodes
//
if (!(Flags & DSGraph::RemoveUnreachableGlobals)) {
// First, add the dead aux call nodes to the set of root nodes for cloning
// -- return value at this call site, if any
// -- actual arguments passed at this call site
// -- callee node at this call site, if this is an indirect call
for (unsigned i = CurIdx, e = AuxFunctionCalls.size(); i != e; ++i) {
if (const DSNode* RetNode = AuxFunctionCalls[i].getRetVal().getNode())
GlobalNodeSet.insert(RetNode);
for (unsigned j=0, N=AuxFunctionCalls[i].getNumPtrArgs(); j < N; ++j)
if (const DSNode* ArgTarget=AuxFunctionCalls[i].getPtrArg(j).getNode())
GlobalNodeSet.insert(ArgTarget);
if (AuxFunctionCalls[i].isIndirectCall())
GlobalNodeSet.insert(AuxFunctionCalls[i].getCalleeNode());
}
// There are no "pre-completed" nodes so use any empty map for those.
// Strip all alloca bits since the current function is only for the BU pass.
// Strip all incomplete bits since they are short-lived properties and they
// will be correctly computed when rematerializing nodes into the functions.
//
NodeMapTy CompletedMap;
GlobalsGraph->cloneReachableSubgraph(*this, GlobalNodeSet,
GlobalNodeMap, CompletedMap,
(DSGraph::StripAllocaBit |
DSGraph::StripIncompleteBit));
}
// Remove all dead aux function calls...
if (!(Flags & DSGraph::RemoveUnreachableGlobals)) {
assert(GlobalsGraph && "No globals graph available??");
// Move the unreachable call nodes to the globals graph...
GlobalsGraph->AuxFunctionCalls.insert(GlobalsGraph->AuxFunctionCalls.end(),
AuxFunctionCalls.begin()+CurIdx,
AuxFunctionCalls.end());
// Copy the unreachable call nodes to the globals graph, updating
// their target pointers using the GlobalNodeMap
for (unsigned i = CurIdx, e = AuxFunctionCalls.size(); i != e; ++i)
GlobalsGraph->AuxFunctionCalls.push_back(DSCallSite(AuxFunctionCalls[i],
GlobalNodeMap));
}
// Crop all the useless ones out...
AuxFunctionCalls.erase(AuxFunctionCalls.begin()+CurIdx,
AuxFunctionCalls.end());
// We are finally done with the GlobalNodeMap so we can clear it and
// then get rid of unused nodes in the GlobalsGraph produced by merging.
GlobalNodeMap.clear();
GlobalsGraph->removeTriviallyDeadNodes();
// At this point, any nodes which are visited, but not alive, are nodes which
// should be moved to the globals graph. Loop over all nodes, eliminating
// completely unreachable nodes, and moving visited nodes to the globals graph
@ -1321,58 +1540,23 @@ void DSGraph::removeDeadNodes(unsigned Flags) {
DSNode *N = Nodes[i];
Nodes[i--] = Nodes.back(); // move node to end of vector
Nodes.pop_back(); // Erase node from alive list.
if (!(Flags & DSGraph::RemoveUnreachableGlobals) && // Not in TD pass
Visited.count(N)) { // Visited but not alive?
GlobalsGraph->Nodes.push_back(N); // Move node to globals graph
N->setParentGraph(GlobalsGraph);
} else { // Otherwise, delete the node
assert((!N->isGlobalNode() ||
(Flags & DSGraph::RemoveUnreachableGlobals))
&& "Killing a global?");
//std::cerr << "[" << i+1 << "/" << DeadNodes.size()
// << "] Node is dead: "; N->dump();
DeadNodes.push_back(N);
N->dropAllReferences();
}
DeadNodes.push_back(N);
N->dropAllReferences();
} else {
assert(Nodes[i]->getForwardNode() == 0 && "Alive forwarded node?");
}
// Now that the nodes have either been deleted or moved to the globals graph,
// loop over the scalarmap, updating the entries for globals...
//
if (!(Flags & DSGraph::RemoveUnreachableGlobals)) { // Not in the TD pass?
// In this array we start the remapping, which can cause merging. Because
// of this, the DSNode pointers in GlobalNodes may be invalidated, so we
// must always go through the ScalarMap (which contains DSNodeHandles [which
// cannot be invalidated by merging]).
//
for (unsigned i = 0, e = GlobalNodes.size(); i != e; ++i) {
Value *G = GlobalNodes[i].first;
ScalarMapTy::iterator I = ScalarMap.find(G);
assert(I != ScalarMap.end() && "Global not in scalar map anymore?");
assert(I->second.getNode() && "Global not pointing to anything?");
assert(!Alive.count(I->second.getNode()) && "Node is alive??");
GlobalsGraph->ScalarMap[G].mergeWith(I->second);
assert(GlobalsGraph->ScalarMap[G].getNode() &&
"Global not pointing to anything?");
ScalarMap.erase(I);
}
// Merging leaves behind silly nodes, we remove them to avoid polluting the
// globals graph.
if (!GlobalNodes.empty())
GlobalsGraph->removeTriviallyDeadNodes();
} else {
// If we are in the top-down pass, remove all unreachable globals from the
// ScalarMap...
for (unsigned i = 0, e = GlobalNodes.size(); i != e; ++i)
if (!Alive.count(GlobalNodes[i].second))
ScalarMap.erase(GlobalNodes[i].first);
// Remove all unreachable globals from the ScalarMap.
// If flag RemoveUnreachableGlobals is set, GlobalNodes has only dead nodes.
// In either case, the dead nodes will not be in the set Alive.
for (unsigned i = 0, e = GlobalNodes.size(); i != e; ++i) {
assert(((Flags & DSGraph::RemoveUnreachableGlobals) ||
!Alive.count(GlobalNodes[i].second)) && "huh? non-dead global");
if (!Alive.count(GlobalNodes[i].second))
ScalarMap.erase(GlobalNodes[i].first);
}
// Loop over all of the dead nodes now, deleting them since their referrer
// count is zero.
// Delete all dead nodes now since their referrer counts are zero.
for (unsigned i = 0, e = DeadNodes.size(); i != e; ++i)
delete DeadNodes[i];
@ -1396,3 +1580,4 @@ void DSGraph::AssertGraphOK() const {
AssertCallNodesInGraph();
AssertAuxCallNodesInGraph();
}