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llvm-6502/lib/Analysis/DataStructure/DataStructure.cpp
Vikram S. Adve 40c600e8f3 Fix comment. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7227 91177308-0d34-0410-b5e6-96231b3b80d8
2003-07-22 12:08:58 +00:00

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//===- DataStructure.cpp - Implement the core data structure analysis -----===//
//
// This file implements the core data structure functionality.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/DSGraph.h"
#include "llvm/Function.h"
#include "llvm/iOther.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Assembly/Writer.h"
#include "Support/STLExtras.h"
#include "Support/Statistic.h"
#include "Support/Timer.h"
#include <algorithm>
namespace {
Statistic<> NumFolds ("dsnode", "Number of nodes completely folded");
Statistic<> NumCallNodesMerged("dsnode", "Number of call nodes merged");
};
namespace DS { // TODO: FIXME
extern TargetData TD;
}
using namespace DS;
DSNode *DSNodeHandle::HandleForwarding() const {
assert(!N->ForwardNH.isNull() && "Can only be invoked if forwarding!");
// Handle node forwarding here!
DSNode *Next = N->ForwardNH.getNode(); // Cause recursive shrinkage
Offset += N->ForwardNH.getOffset();
if (--N->NumReferrers == 0) {
// Removing the last referrer to the node, sever the forwarding link
N->stopForwarding();
}
N = Next;
N->NumReferrers++;
if (N->Size <= Offset) {
assert(N->Size <= 1 && "Forwarded to shrunk but not collapsed node?");
Offset = 0;
}
return N;
}
//===----------------------------------------------------------------------===//
// DSNode Implementation
//===----------------------------------------------------------------------===//
DSNode::DSNode(const Type *T, DSGraph *G)
: NumReferrers(0), Size(0), ParentGraph(G), Ty(Type::VoidTy), NodeType(0) {
// Add the type entry if it is specified...
if (T) mergeTypeInfo(T, 0);
G->getNodes().push_back(this);
}
// DSNode copy constructor... do not copy over the referrers list!
DSNode::DSNode(const DSNode &N, DSGraph *G)
: NumReferrers(0), Size(N.Size), ParentGraph(G),
Ty(N.Ty), Links(N.Links), Globals(N.Globals), NodeType(N.NodeType) {
G->getNodes().push_back(this);
}
void DSNode::assertOK() const {
assert((Ty != Type::VoidTy ||
Ty == Type::VoidTy && (Size == 0 ||
(NodeType & DSNode::Array))) &&
"Node not OK!");
assert(ParentGraph && "Node has no parent?");
const DSGraph::ScalarMapTy &SM = ParentGraph->getScalarMap();
for (unsigned i = 0, e = Globals.size(); i != e; ++i) {
assert(SM.find(Globals[i]) != SM.end());
assert(SM.find(Globals[i])->second.getNode() == this);
}
}
/// forwardNode - Mark this node as being obsolete, and all references to it
/// should be forwarded to the specified node and offset.
///
void DSNode::forwardNode(DSNode *To, unsigned Offset) {
assert(this != To && "Cannot forward a node to itself!");
assert(ForwardNH.isNull() && "Already forwarding from this node!");
if (To->Size <= 1) Offset = 0;
assert((Offset < To->Size || (Offset == To->Size && Offset == 0)) &&
"Forwarded offset is wrong!");
ForwardNH.setNode(To);
ForwardNH.setOffset(Offset);
NodeType = DEAD;
Size = 0;
Ty = Type::VoidTy;
}
// 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;
}
}
/// foldNodeCompletely - If we determine that this node has some funny
/// behavior happening to it that we cannot represent, we fold it down to a
/// single, completely pessimistic, node. This node is represented as a
/// single byte with a single TypeEntry of "void".
///
void DSNode::foldNodeCompletely() {
if (isNodeCompletelyFolded()) return; // If this node is already folded...
++NumFolds;
// Create the node we are going to forward to...
DSNode *DestNode = new DSNode(0, ParentGraph);
DestNode->NodeType = NodeType|DSNode::Array;
DestNode->Ty = Type::VoidTy;
DestNode->Size = 1;
DestNode->Globals.swap(Globals);
// Start forwarding to the destination node...
forwardNode(DestNode, 0);
if (Links.size()) {
DestNode->Links.push_back(Links[0]);
DSNodeHandle NH(DestNode);
// If we have links, merge all of our outgoing links together...
for (unsigned i = Links.size()-1; i != 0; --i)
NH.getNode()->Links[0].mergeWith(Links[i]);
Links.clear();
} else {
DestNode->Links.resize(1);
}
}
/// isNodeCompletelyFolded - Return true if this node has been completely
/// folded down to something that can never be expanded, effectively losing
/// all of the field sensitivity that may be present in the node.
///
bool DSNode::isNodeCompletelyFolded() const {
return getSize() == 1 && Ty == Type::VoidTy && isArray();
}
namespace {
/// TypeElementWalker Class - Used for implementation of physical subtyping...
///
class TypeElementWalker {
struct StackState {
const Type *Ty;
unsigned Offset;
unsigned Idx;
StackState(const Type *T, unsigned Off = 0)
: Ty(T), Offset(Off), Idx(0) {}
};
std::vector<StackState> Stack;
public:
TypeElementWalker(const Type *T) {
Stack.push_back(T);
StepToLeaf();
}
bool isDone() const { return Stack.empty(); }
const Type *getCurrentType() const { return Stack.back().Ty; }
unsigned getCurrentOffset() const { return Stack.back().Offset; }
void StepToNextType() {
PopStackAndAdvance();
StepToLeaf();
}
private:
/// PopStackAndAdvance - Pop the current element off of the stack and
/// advance the underlying element to the next contained member.
void PopStackAndAdvance() {
assert(!Stack.empty() && "Cannot pop an empty stack!");
Stack.pop_back();
while (!Stack.empty()) {
StackState &SS = Stack.back();
if (const StructType *ST = dyn_cast<StructType>(SS.Ty)) {
++SS.Idx;
if (SS.Idx != ST->getElementTypes().size()) {
const StructLayout *SL = TD.getStructLayout(ST);
SS.Offset += SL->MemberOffsets[SS.Idx]-SL->MemberOffsets[SS.Idx-1];
return;
}
Stack.pop_back(); // At the end of the structure
} else {
const ArrayType *AT = cast<ArrayType>(SS.Ty);
++SS.Idx;
if (SS.Idx != AT->getNumElements()) {
SS.Offset += TD.getTypeSize(AT->getElementType());
return;
}
Stack.pop_back(); // At the end of the array
}
}
}
/// StepToLeaf - Used by physical subtyping to move to the first leaf node
/// on the type stack.
void StepToLeaf() {
if (Stack.empty()) return;
while (!Stack.empty() && !Stack.back().Ty->isFirstClassType()) {
StackState &SS = Stack.back();
if (const StructType *ST = dyn_cast<StructType>(SS.Ty)) {
if (ST->getElementTypes().empty()) {
assert(SS.Idx == 0);
PopStackAndAdvance();
} else {
// Step into the structure...
assert(SS.Idx < ST->getElementTypes().size());
const StructLayout *SL = TD.getStructLayout(ST);
Stack.push_back(StackState(ST->getElementTypes()[SS.Idx],
SS.Offset+SL->MemberOffsets[SS.Idx]));
}
} else {
const ArrayType *AT = cast<ArrayType>(SS.Ty);
if (AT->getNumElements() == 0) {
assert(SS.Idx == 0);
PopStackAndAdvance();
} else {
// Step into the array...
assert(SS.Idx < AT->getNumElements());
Stack.push_back(StackState(AT->getElementType(),
SS.Offset+SS.Idx*
TD.getTypeSize(AT->getElementType())));
}
}
}
}
};
}
/// ElementTypesAreCompatible - Check to see if the specified types are
/// "physically" compatible. If so, return true, else return false. We only
/// have to check the fields in T1: T2 may be larger than T1.
///
static bool ElementTypesAreCompatible(const Type *T1, const Type *T2) {
TypeElementWalker T1W(T1), T2W(T2);
while (!T1W.isDone() && !T2W.isDone()) {
if (T1W.getCurrentOffset() != T2W.getCurrentOffset())
return false;
const Type *T1 = T1W.getCurrentType();
const Type *T2 = T2W.getCurrentType();
if (T1 != T2 && !T1->isLosslesslyConvertibleTo(T2))
return false;
T1W.StepToNextType();
T2W.StepToNextType();
}
return T1W.isDone();
}
/// mergeTypeInfo - This method merges the specified type into the current node
/// at the specified offset. This may update the current node's type record if
/// this gives more information to the node, it may do nothing to the node if
/// this information is already known, or it may merge the node completely (and
/// return true) if the information is incompatible with what is already known.
///
/// This method returns true if the node is completely folded, otherwise false.
///
bool DSNode::mergeTypeInfo(const Type *NewTy, unsigned Offset,
bool FoldIfIncompatible) {
// Check to make sure the Size member is up-to-date. Size can be one of the
// following:
// Size = 0, Ty = Void: Nothing is known about this node.
// Size = 0, Ty = FnTy: FunctionPtr doesn't have a size, so we use zero
// Size = 1, Ty = Void, Array = 1: The node is collapsed
// Otherwise, sizeof(Ty) = Size
//
assert(((Size == 0 && Ty == Type::VoidTy && !isArray()) ||
(Size == 0 && !Ty->isSized() && !isArray()) ||
(Size == 1 && Ty == Type::VoidTy && isArray()) ||
(Size == 0 && !Ty->isSized() && !isArray()) ||
(TD.getTypeSize(Ty) == Size)) &&
"Size member of DSNode doesn't match the type structure!");
assert(NewTy != Type::VoidTy && "Cannot merge void type into DSNode!");
if (Offset == 0 && NewTy == Ty)
return false; // This should be a common case, handle it efficiently
// Return true immediately if the node is completely folded.
if (isNodeCompletelyFolded()) return true;
// If this is an array type, eliminate the outside arrays because they won't
// be used anyway. This greatly reduces the size of large static arrays used
// as global variables, for example.
//
bool WillBeArray = false;
while (const ArrayType *AT = dyn_cast<ArrayType>(NewTy)) {
// FIXME: we might want to keep small arrays, but must be careful about
// things like: [2 x [10000 x int*]]
NewTy = AT->getElementType();
WillBeArray = true;
}
// Figure out how big the new type we're merging in is...
unsigned NewTySize = NewTy->isSized() ? TD.getTypeSize(NewTy) : 0;
// Otherwise check to see if we can fold this type into the current node. If
// we can't, we fold the node completely, if we can, we potentially update our
// internal state.
//
if (Ty == Type::VoidTy) {
// If this is the first type that this node has seen, just accept it without
// question....
assert(Offset == 0 && "Cannot have an offset into a void node!");
assert(!isArray() && "This shouldn't happen!");
Ty = NewTy;
NodeType &= ~Array;
if (WillBeArray) NodeType |= Array;
Size = NewTySize;
// Calculate the number of outgoing links from this node.
Links.resize((Size+DS::PointerSize-1) >> DS::PointerShift);
return false;
}
// Handle node expansion case here...
if (Offset+NewTySize > Size) {
// It is illegal to grow this node if we have treated it as an array of
// objects...
if (isArray()) {
if (FoldIfIncompatible) foldNodeCompletely();
return true;
}
if (Offset) { // We could handle this case, but we don't for now...
std::cerr << "UNIMP: Trying to merge a growth type into "
<< "offset != 0: Collapsing!\n";
if (FoldIfIncompatible) foldNodeCompletely();
return true;
}
// Okay, the situation is nice and simple, we are trying to merge a type in
// at offset 0 that is bigger than our current type. Implement this by
// switching to the new type and then merge in the smaller one, which should
// hit the other code path here. If the other code path decides it's not
// ok, it will collapse the node as appropriate.
//
const Type *OldTy = Ty;
Ty = NewTy;
NodeType &= ~Array;
if (WillBeArray) NodeType |= Array;
Size = NewTySize;
// Must grow links to be the appropriate size...
Links.resize((Size+DS::PointerSize-1) >> DS::PointerShift);
// Merge in the old type now... which is guaranteed to be smaller than the
// "current" type.
return mergeTypeInfo(OldTy, 0);
}
assert(Offset <= Size &&
"Cannot merge something into a part of our type that doesn't exist!");
// Find the section of Ty that NewTy overlaps with... first we find the
// type that starts at offset Offset.
//
unsigned O = 0;
const Type *SubType = Ty;
while (O < Offset) {
assert(Offset-O < TD.getTypeSize(SubType) && "Offset out of range!");
switch (SubType->getPrimitiveID()) {
case Type::StructTyID: {
const StructType *STy = cast<StructType>(SubType);
const StructLayout &SL = *TD.getStructLayout(STy);
unsigned i = 0, e = SL.MemberOffsets.size();
for (; i+1 < e && SL.MemberOffsets[i+1] <= Offset-O; ++i)
/* empty */;
// The offset we are looking for must be in the i'th element...
SubType = STy->getElementTypes()[i];
O += SL.MemberOffsets[i];
break;
}
case Type::ArrayTyID: {
SubType = cast<ArrayType>(SubType)->getElementType();
unsigned ElSize = TD.getTypeSize(SubType);
unsigned Remainder = (Offset-O) % ElSize;
O = Offset-Remainder;
break;
}
default:
if (FoldIfIncompatible) foldNodeCompletely();
return true;
}
}
assert(O == Offset && "Could not achieve the correct offset!");
// If we found our type exactly, early exit
if (SubType == NewTy) return false;
unsigned SubTypeSize = SubType->isSized() ? TD.getTypeSize(SubType) : 0;
// Ok, we are getting desperate now. Check for physical subtyping, where we
// just require each element in the node to be compatible.
if (NewTySize <= SubTypeSize && NewTySize && NewTySize < 256 &&
SubTypeSize && SubTypeSize < 256 &&
ElementTypesAreCompatible(NewTy, SubType))
return false;
// Okay, so we found the leader type at the offset requested. Search the list
// of types that starts at this offset. If SubType is currently an array or
// structure, the type desired may actually be the first element of the
// composite type...
//
unsigned PadSize = SubTypeSize; // Size, including pad memory which is ignored
while (SubType != NewTy) {
const Type *NextSubType = 0;
unsigned NextSubTypeSize = 0;
unsigned NextPadSize = 0;
switch (SubType->getPrimitiveID()) {
case Type::StructTyID: {
const StructType *STy = cast<StructType>(SubType);
const StructLayout &SL = *TD.getStructLayout(STy);
if (SL.MemberOffsets.size() > 1)
NextPadSize = SL.MemberOffsets[1];
else
NextPadSize = SubTypeSize;
NextSubType = STy->getElementTypes()[0];
NextSubTypeSize = TD.getTypeSize(NextSubType);
break;
}
case Type::ArrayTyID:
NextSubType = cast<ArrayType>(SubType)->getElementType();
NextSubTypeSize = TD.getTypeSize(NextSubType);
NextPadSize = NextSubTypeSize;
break;
default: ;
// fall out
}
if (NextSubType == 0)
break; // In the default case, break out of the loop
if (NextPadSize < NewTySize)
break; // Don't allow shrinking to a smaller type than NewTySize
SubType = NextSubType;
SubTypeSize = NextSubTypeSize;
PadSize = NextPadSize;
}
// If we found the type exactly, return it...
if (SubType == NewTy)
return false;
// Check to see if we have a compatible, but different type...
if (NewTySize == SubTypeSize) {
// Check to see if this type is obviously convertible... int -> uint f.e.
if (NewTy->isLosslesslyConvertibleTo(SubType))
return false;
// Check to see if we have a pointer & integer mismatch going on here,
// loading a pointer as a long, for example.
//
if (SubType->isInteger() && isa<PointerType>(NewTy) ||
NewTy->isInteger() && isa<PointerType>(SubType))
return false;
} else if (NewTySize > SubTypeSize && NewTySize <= PadSize) {
// We are accessing the field, plus some structure padding. Ignore the
// structure padding.
return false;
}
Module *M = 0;
if (getParentGraph()->getReturnNodes().size())
M = getParentGraph()->getReturnNodes().begin()->first->getParent();
DEBUG(std::cerr << "MergeTypeInfo Folding OrigTy: ";
WriteTypeSymbolic(std::cerr, Ty, M) << "\n due to:";
WriteTypeSymbolic(std::cerr, NewTy, M) << " @ " << Offset << "!\n"
<< "SubType: ";
WriteTypeSymbolic(std::cerr, SubType, M) << "\n\n");
if (FoldIfIncompatible) foldNodeCompletely();
return true;
}
// 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 Offset, const DSNodeHandle &NH) {
if (NH.getNode() == 0) return; // Nothing to do
DSNodeHandle &ExistingEdge = getLink(Offset);
if (ExistingEdge.getNode()) {
// Merge the two nodes...
ExistingEdge.mergeWith(NH);
} else { // No merging to perform...
setLink(Offset, NH); // Just force a link in there...
}
}
// MergeSortedVectors - Efficiently merge a vector into another vector where
// duplicates are not allowed and both are sorted. This assumes that 'T's are
// efficiently copyable and have sane comparison semantics.
//
static void MergeSortedVectors(std::vector<GlobalValue*> &Dest,
const std::vector<GlobalValue*> &Src) {
// By far, the most common cases will be the simple ones. In these cases,
// avoid having to allocate a temporary vector...
//
if (Src.empty()) { // Nothing to merge in...
return;
} else if (Dest.empty()) { // Just copy the result in...
Dest = Src;
} else if (Src.size() == 1) { // Insert a single element...
const GlobalValue *V = Src[0];
std::vector<GlobalValue*>::iterator I =
std::lower_bound(Dest.begin(), Dest.end(), V);
if (I == Dest.end() || *I != Src[0]) // If not already contained...
Dest.insert(I, Src[0]);
} else if (Dest.size() == 1) {
GlobalValue *Tmp = Dest[0]; // Save value in temporary...
Dest = Src; // Copy over list...
std::vector<GlobalValue*>::iterator I =
std::lower_bound(Dest.begin(), Dest.end(), Tmp);
if (I == Dest.end() || *I != Tmp) // If not already contained...
Dest.insert(I, Tmp);
} else {
// Make a copy to the side of Dest...
std::vector<GlobalValue*> Old(Dest);
// Make space for all of the type entries now...
Dest.resize(Dest.size()+Src.size());
// Merge the two sorted ranges together... into Dest.
std::merge(Old.begin(), Old.end(), Src.begin(), Src.end(), Dest.begin());
// Now erase any duplicate entries that may have accumulated into the
// vectors (because they were in both of the input sets)
Dest.erase(std::unique(Dest.begin(), Dest.end()), Dest.end());
}
}
// MergeNodes() - Helper function for DSNode::mergeWith().
// This function does the hard work of merging two nodes, CurNodeH
// and NH after filtering out trivial cases and making sure that
// CurNodeH.offset >= NH.offset.
//
// ***WARNING***
// Since merging may cause either node to go away, we must always
// use the node-handles to refer to the nodes. These node handles are
// automatically updated during merging, so will always provide access
// to the correct node after a merge.
//
void DSNode::MergeNodes(DSNodeHandle& CurNodeH, DSNodeHandle& NH) {
assert(CurNodeH.getOffset() >= NH.getOffset() &&
"This should have been enforced in the caller.");
// Now we know that Offset >= NH.Offset, so convert it so our "Offset" (with
// respect to NH.Offset) is now zero. NOffset is the distance from the base
// of our object that N starts from.
//
unsigned NOffset = CurNodeH.getOffset()-NH.getOffset();
unsigned NSize = NH.getNode()->getSize();
// If the two nodes are of different size, and the smaller node has the array
// bit set, collapse!
if (NSize != CurNodeH.getNode()->getSize()) {
if (NSize < CurNodeH.getNode()->getSize()) {
if (NH.getNode()->isArray())
NH.getNode()->foldNodeCompletely();
} else if (CurNodeH.getNode()->isArray()) {
NH.getNode()->foldNodeCompletely();
}
}
// Merge the type entries of the two nodes together...
if (NH.getNode()->Ty != Type::VoidTy)
CurNodeH.getNode()->mergeTypeInfo(NH.getNode()->Ty, NOffset);
assert(!CurNodeH.getNode()->isDeadNode());
// If we are merging a node with a completely folded node, then both nodes are
// now completely folded.
//
if (CurNodeH.getNode()->isNodeCompletelyFolded()) {
if (!NH.getNode()->isNodeCompletelyFolded()) {
NH.getNode()->foldNodeCompletely();
assert(NH.getNode() && NH.getOffset() == 0 &&
"folding did not make offset 0?");
NOffset = NH.getOffset();
NSize = NH.getNode()->getSize();
assert(NOffset == 0 && NSize == 1);
}
} else if (NH.getNode()->isNodeCompletelyFolded()) {
CurNodeH.getNode()->foldNodeCompletely();
assert(CurNodeH.getNode() && CurNodeH.getOffset() == 0 &&
"folding did not make offset 0?");
NOffset = NH.getOffset();
NSize = NH.getNode()->getSize();
assert(NOffset == 0 && NSize == 1);
}
DSNode *N = NH.getNode();
if (CurNodeH.getNode() == N || N == 0) return;
assert(!CurNodeH.getNode()->isDeadNode());
// Merge the NodeType information...
CurNodeH.getNode()->NodeType |= N->NodeType;
// Start forwarding to the new node!
N->forwardNode(CurNodeH.getNode(), NOffset);
assert(!CurNodeH.getNode()->isDeadNode());
// Make all of the outgoing links of N now be outgoing links of CurNodeH.
//
for (unsigned i = 0; i < N->getNumLinks(); ++i) {
DSNodeHandle &Link = N->getLink(i << DS::PointerShift);
if (Link.getNode()) {
// Compute the offset into the current node at which to
// merge this link. In the common case, this is a linear
// relation to the offset in the original node (with
// wrapping), but if the current node gets collapsed due to
// recursive merging, we must make sure to merge in all remaining
// links at offset zero.
unsigned MergeOffset = 0;
DSNode *CN = CurNodeH.getNode();
if (CN->Size != 1)
MergeOffset = ((i << DS::PointerShift)+NOffset) % CN->getSize();
CN->addEdgeTo(MergeOffset, Link);
}
}
// Now that there are no outgoing edges, all of the Links are dead.
N->Links.clear();
// Merge the globals list...
if (!N->Globals.empty()) {
MergeSortedVectors(CurNodeH.getNode()->Globals, N->Globals);
// Delete the globals from the old node...
std::vector<GlobalValue*>().swap(N->Globals);
}
}
// mergeWith - Merge this node and the specified node, moving all links to and
// from the argument node into the current node, deleting the node argument.
// Offset indicates what offset the specified node is to be merged into the
// current node.
//
// The specified node may be a null pointer (in which case, nothing happens).
//
void DSNode::mergeWith(const DSNodeHandle &NH, unsigned Offset) {
DSNode *N = NH.getNode();
if (N == 0 || (N == this && NH.getOffset() == Offset))
return; // Noop
assert(!N->isDeadNode() && !isDeadNode());
assert(!hasNoReferrers() && "Should not try to fold a useless node!");
if (N == this) {
// We cannot merge two pieces of the same node together, collapse the node
// completely.
DEBUG(std::cerr << "Attempting to merge two chunks of"
<< " the same node together!\n");
foldNodeCompletely();
return;
}
// If both nodes are not at offset 0, make sure that we are merging the node
// at an later offset into the node with the zero offset.
//
if (Offset < NH.getOffset()) {
N->mergeWith(DSNodeHandle(this, Offset), NH.getOffset());
return;
} else if (Offset == NH.getOffset() && getSize() < N->getSize()) {
// If the offsets are the same, merge the smaller node into the bigger node
N->mergeWith(DSNodeHandle(this, Offset), NH.getOffset());
return;
}
// Ok, now we can merge the two nodes. Use a static helper that works with
// two node handles, since "this" may get merged away at intermediate steps.
DSNodeHandle CurNodeH(this, Offset);
DSNodeHandle NHCopy(NH);
DSNode::MergeNodes(CurNodeH, NHCopy);
}
//===----------------------------------------------------------------------===//
// DSCallSite Implementation
//===----------------------------------------------------------------------===//
// Define here to avoid including iOther.h and BasicBlock.h in DSGraph.h
Function &DSCallSite::getCaller() const {
return *Inst->getParent()->getParent();
}
//===----------------------------------------------------------------------===//
// DSGraph Implementation
//===----------------------------------------------------------------------===//
/// getFunctionNames - Return a space separated list of the name of the
/// functions in this graph (if any)
std::string DSGraph::getFunctionNames() const {
switch (getReturnNodes().size()) {
case 0: return "Globals graph";
case 1: return getReturnNodes().begin()->first->getName();
default:
std::string Return;
for (DSGraph::ReturnNodesTy::const_iterator I = getReturnNodes().begin();
I != getReturnNodes().end(); ++I)
Return += I->first->getName() + " ";
Return.erase(Return.end()-1, Return.end()); // Remove last space character
return Return;
}
}
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();
// Drop all intra-node references, so that assertions don't fail...
std::for_each(Nodes.begin(), Nodes.end(),
std::mem_fun(&DSNode::dropAllReferences));
// 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); }
/// remapLinks - Change all of the Links in the current node according to the
/// specified mapping.
///
void DSNode::remapLinks(DSGraph::NodeMapTy &OldNodeMap) {
for (unsigned i = 0, e = Links.size(); i != e; ++i) {
DSNodeHandle &H = OldNodeMap[Links[i].getNode()];
Links[i].setNode(H.getNode());
Links[i].setOffset(Links[i].getOffset()+H.getOffset());
}
}
/// 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.
///
/// The CloneFlags member controls various aspects of the cloning process.
///
void DSGraph::cloneInto(const DSGraph &G, ScalarMapTy &OldValMap,
ReturnNodesTy &OldReturnNodes, NodeMapTy &OldNodeMap,
unsigned CloneFlags) {
assert(OldNodeMap.empty() && "Returned OldNodeMap should be empty!");
assert(&G != this && "Cannot clone graph into itself!");
unsigned FN = Nodes.size(); // First new node...
// Duplicate all of the nodes, populating the node map...
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)
| ((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];
DSNode *New = new DSNode(*Old, this);
New->maskNodeTypes(~BitsToClear);
OldNodeMap[Old] = New;
}
#ifndef NDEBUG
Timer::addPeakMemoryMeasurement();
#endif
// Rewrite the links in the new nodes to point into the current graph now.
for (unsigned i = FN, e = Nodes.size(); i != e; ++i)
Nodes[i]->remapLinks(OldNodeMap);
// Copy the scalar map... merging all of the global nodes...
for (ScalarMapTy::const_iterator I = G.ScalarMap.begin(),
E = G.ScalarMap.end(); I != E; ++I) {
DSNodeHandle &MappedNode = OldNodeMap[I->second.getNode()];
DSNodeHandle &H = OldValMap[I->first];
H.mergeWith(DSNodeHandle(MappedNode.getNode(),
I->second.getOffset()+MappedNode.getOffset()));
// If this is a global, add the global to this fn or merge if already exists
if (GlobalValue* GV = dyn_cast<GlobalValue>(I->first)) {
ScalarMap[GV].mergeWith(H);
InlinedGlobals.insert(GV);
}
}
if (!(CloneFlags & DontCloneCallNodes)) {
// Copy the function calls list...
unsigned FC = FunctionCalls.size(); // FirstCall
FunctionCalls.reserve(FC+G.FunctionCalls.size());
for (unsigned i = 0, ei = G.FunctionCalls.size(); i != ei; ++i)
FunctionCalls.push_back(DSCallSite(G.FunctionCalls[i], OldNodeMap));
}
if (!(CloneFlags & DontCloneAuxCallNodes)) {
// Copy the auxillary function calls list...
unsigned FC = AuxFunctionCalls.size(); // FirstCall
AuxFunctionCalls.reserve(FC+G.AuxFunctionCalls.size());
for (unsigned i = 0, ei = G.AuxFunctionCalls.size(); i != ei; ++i)
AuxFunctionCalls.push_back(DSCallSite(G.AuxFunctionCalls[i], OldNodeMap));
}
// Map the return node pointers over...
for (ReturnNodesTy::const_iterator I = G.getReturnNodes().begin(),
E = G.getReturnNodes().end(); I != E; ++I) {
const DSNodeHandle &Ret = I->second;
DSNodeHandle &MappedRet = OldNodeMap[Ret.getNode()];
OldReturnNodes.insert(std::make_pair(I->first,
DSNodeHandle(MappedRet.getNode(),
MappedRet.getOffset()+Ret.getOffset())));
}
}
/// mergeInGraph - The method is used for merging graphs together. If the
/// argument graph is not *this, it makes a clone of the specified graph, then
/// merges the nodes specified in the call site with the formal arguments in the
/// graph.
///
void DSGraph::mergeInGraph(const DSCallSite &CS, Function &F,
const DSGraph &Graph, unsigned CloneFlags) {
ScalarMapTy OldValMap, *ScalarMap;
DSNodeHandle RetVal;
// If this is not a recursive call, clone the graph into this graph...
if (&Graph != this) {
// Clone the callee's graph into the current graph, keeping
// track of where scalars in the old graph _used_ to point,
// and of the new nodes matching nodes of the old graph.
NodeMapTy OldNodeMap;
// The clone call may invalidate any of the vectors in the data
// structure graph. Strip locals and don't copy the list of callers
ReturnNodesTy OldRetNodes;
cloneInto(Graph, OldValMap, OldRetNodes, OldNodeMap, CloneFlags);
// We need to map the arguments for the function to the cloned nodes old
// argument values. Do this now.
RetVal = OldRetNodes[&F];
ScalarMap = &OldValMap;
} else {
RetVal = getReturnNodeFor(F);
ScalarMap = &getScalarMap();
}
// Merge the return value with the return value of the context...
RetVal.mergeWith(CS.getRetVal());
// Resolve all of the function arguments...
Function::aiterator AI = F.abegin();
for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i, ++AI) {
// Advance the argument iterator to the first pointer argument...
while (AI != F.aend() && !isPointerType(AI->getType())) {
++AI;
#ifndef NDEBUG
if (AI == F.aend())
std::cerr << "Bad call to Function: " << F.getName() << "\n";
#endif
}
if (AI == F.aend()) break;
// Add the link from the argument scalar to the provided value
assert(ScalarMap->count(AI) && "Argument not in scalar map?");
DSNodeHandle &NH = (*ScalarMap)[AI];
assert(NH.getNode() && "Pointer argument without scalarmap entry?");
NH.mergeWith(CS.getPtrArg(i));
}
}
/// getCallSiteForArguments - Get the arguments and return value bindings for
/// the specified function in the current graph.
///
DSCallSite DSGraph::getCallSiteForArguments(Function &F) const {
std::vector<DSNodeHandle> Args;
for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
if (isPointerType(I->getType()))
Args.push_back(getScalarMap().find(I)->second);
return DSCallSite(*(CallInst*)0, getReturnNodeFor(F), &F, Args);
}
// 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 incomplete 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->isIncomplete()) return;
// Actually mark the node
N->setIncompleteMarker();
// Recusively process children...
for (unsigned i = 0, e = N->getSize(); i < e; i += DS::PointerSize)
if (DSNode *DSN = N->getLink(i).getNode())
markIncompleteNode(DSN);
}
static void markIncomplete(DSCallSite &Call) {
// Then the return value is certainly incomplete!
markIncompleteNode(Call.getRetVal().getNode());
// All objects pointed to by function arguments are incomplete!
for (unsigned i = 0, e = Call.getNumPtrArgs(); i != e; ++i)
markIncompleteNode(Call.getPtrArg(i).getNode());
}
// 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(unsigned Flags) {
// Mark any incoming arguments as incomplete...
if (Flags & DSGraph::MarkFormalArgs)
for (ReturnNodesTy::iterator FI = ReturnNodes.begin(), E =ReturnNodes.end();
FI != E; ++FI) {
Function &F = *FI->first;
if (F.getName() != "main")
for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
if (isPointerType(I->getType()) &&
ScalarMap.find(I) != ScalarMap.end())
markIncompleteNode(ScalarMap[I].getNode());
}
// Mark stuff passed into functions calls as being incomplete...
if (!shouldPrintAuxCalls())
for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i)
markIncomplete(FunctionCalls[i]);
else
for (unsigned i = 0, e = AuxFunctionCalls.size(); i != e; ++i)
markIncomplete(AuxFunctionCalls[i]);
// Mark all global nodes as incomplete...
if ((Flags & DSGraph::IgnoreGlobals) == 0)
for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
if (Nodes[i]->isGlobalNode() && Nodes[i]->getNumLinks())
markIncompleteNode(Nodes[i]);
}
static inline void killIfUselessEdge(DSNodeHandle &Edge) {
if (DSNode *N = Edge.getNode()) // Is there an edge?
if (N->getNumReferrers() == 1) // Does it point to a lonely node?
// No interesting info?
if ((N->getNodeFlags() & ~DSNode::Incomplete) == 0 &&
N->getType() == Type::VoidTy && !N->isNodeCompletelyFolded())
Edge.setNode(0); // Kill the edge!
}
static inline bool nodeContainsExternalFunction(const DSNode *N) {
const std::vector<GlobalValue*> &Globals = N->getGlobals();
for (unsigned i = 0, e = Globals.size(); i != e; ++i)
if (Globals[i]->isExternal())
return true;
return false;
}
static void removeIdenticalCalls(std::vector<DSCallSite> &Calls) {
// Remove trivially identical function calls
unsigned NumFns = Calls.size();
std::sort(Calls.begin(), Calls.end()); // Sort by callee as primary key!
// Scan the call list cleaning it up as necessary...
DSNode *LastCalleeNode = 0;
Function *LastCalleeFunc = 0;
unsigned NumDuplicateCalls = 0;
bool LastCalleeContainsExternalFunction = false;
for (unsigned i = 0; i != Calls.size(); ++i) {
DSCallSite &CS = Calls[i];
// If the Callee is a useless edge, this must be an unreachable call site,
// eliminate it.
if (CS.isIndirectCall() && CS.getCalleeNode()->getNumReferrers() == 1 &&
CS.getCalleeNode()->getNodeFlags() == 0) { // No useful info?
std::cerr << "WARNING: Useless call site found??\n";
CS.swap(Calls.back());
Calls.pop_back();
--i;
} else {
// If the return value or any arguments point to a void node with no
// information at all in it, and the call node is the only node to point
// to it, remove the edge to the node (killing the node).
//
killIfUselessEdge(CS.getRetVal());
for (unsigned a = 0, e = CS.getNumPtrArgs(); a != e; ++a)
killIfUselessEdge(CS.getPtrArg(a));
// If this call site calls the same function as the last call site, and if
// the function pointer contains an external function, this node will
// never be resolved. Merge the arguments of the call node because no
// information will be lost.
//
if ((CS.isDirectCall() && CS.getCalleeFunc() == LastCalleeFunc) ||
(CS.isIndirectCall() && CS.getCalleeNode() == LastCalleeNode)) {
++NumDuplicateCalls;
if (NumDuplicateCalls == 1) {
if (LastCalleeNode)
LastCalleeContainsExternalFunction =
nodeContainsExternalFunction(LastCalleeNode);
else
LastCalleeContainsExternalFunction = LastCalleeFunc->isExternal();
}
#if 1
if (LastCalleeContainsExternalFunction ||
// This should be more than enough context sensitivity!
// FIXME: Evaluate how many times this is tripped!
NumDuplicateCalls > 20) {
DSCallSite &OCS = Calls[i-1];
OCS.mergeWith(CS);
// The node will now be eliminated as a duplicate!
if (CS.getNumPtrArgs() < OCS.getNumPtrArgs())
CS = OCS;
else if (CS.getNumPtrArgs() > OCS.getNumPtrArgs())
OCS = CS;
}
#endif
} else {
if (CS.isDirectCall()) {
LastCalleeFunc = CS.getCalleeFunc();
LastCalleeNode = 0;
} else {
LastCalleeNode = CS.getCalleeNode();
LastCalleeFunc = 0;
}
NumDuplicateCalls = 0;
}
}
}
Calls.erase(std::unique(Calls.begin(), Calls.end()),
Calls.end());
// Track the number of call nodes merged away...
NumCallNodesMerged += NumFns-Calls.size();
DEBUG(if (NumFns != Calls.size())
std::cerr << "Merged " << (NumFns-Calls.size()) << " call nodes.\n";);
}
// removeTriviallyDeadNodes - 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::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
// context), and it has no incoming edges. If it is a global node it may
// have all of these properties and still have incoming edges, due to the
// scalar map, so we check those now.
//
if (Node->getNumReferrers() == Node->getGlobals().size()) {
const std::vector<GlobalValue*> &Globals = Node->getGlobals();
// 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!");
}
// Make sure NumReferrers still agrees, if so, the node is truly dead.
if (Node->getNumReferrers() == Globals.size()) {
for (unsigned j = 0, e = Globals.size(); j != e; ++j)
ScalarMap.erase(Globals[j]);
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()) {
// This node is dead!
delete Node; // Free memory...
Nodes[i--] = Nodes.back();
Nodes.pop_back(); // Remove from node list...
}
}
}
/// markReachableNodes - This method recursively traverses the specified
/// DSNodes, marking any nodes which are reachable. All reachable nodes it adds
/// to the set, which allows it to only traverse visited nodes once.
///
void DSNode::markReachableNodes(hash_set<DSNode*> &ReachableNodes) {
if (this == 0) return;
assert(getForwardNode() == 0 && "Cannot mark a forwarded node!");
if (ReachableNodes.count(this)) return; // Already marked reachable
ReachableNodes.insert(this); // Is reachable now
for (unsigned i = 0, e = getSize(); i < e; i += DS::PointerSize)
getLink(i).getNode()->markReachableNodes(ReachableNodes);
}
void DSCallSite::markReachableNodes(hash_set<DSNode*> &Nodes) {
getRetVal().getNode()->markReachableNodes(Nodes);
if (isIndirectCall()) getCalleeNode()->markReachableNodes(Nodes);
for (unsigned i = 0, e = getNumPtrArgs(); i != e; ++i)
getPtrArg(i).getNode()->markReachableNodes(Nodes);
}
// CanReachAliveNodes - Simple graph walker that recursively traverses the graph
// looking for a node that is marked alive. If an alive node is found, return
// true, otherwise return false. If an alive node is reachable, this node is
// marked as alive...
//
static bool CanReachAliveNodes(DSNode *N, hash_set<DSNode*> &Alive,
hash_set<DSNode*> &Visited,
bool IgnoreGlobals) {
if (N == 0) return false;
assert(N->getForwardNode() == 0 && "Cannot mark a forwarded node!");
// If this is a global node, it will end up in the globals graph anyway, so we
// don't need to worry about it.
if (IgnoreGlobals && N->isGlobalNode()) return false;
// If we know that this node is alive, return so!
if (Alive.count(N)) return true;
// Otherwise, we don't think the node is alive yet, check for infinite
// recursion.
if (Visited.count(N)) return false; // Found a cycle
Visited.insert(N); // No recursion, insert into Visited...
for (unsigned i = 0, e = N->getSize(); i < e; i += DS::PointerSize)
if (CanReachAliveNodes(N->getLink(i).getNode(), Alive, Visited,
IgnoreGlobals)) {
N->markReachableNodes(Alive);
return true;
}
return false;
}
// CallSiteUsesAliveArgs - Return true if the specified call site can reach any
// alive nodes.
//
static bool CallSiteUsesAliveArgs(DSCallSite &CS, hash_set<DSNode*> &Alive,
hash_set<DSNode*> &Visited,
bool IgnoreGlobals) {
if (CanReachAliveNodes(CS.getRetVal().getNode(), Alive, Visited,
IgnoreGlobals))
return true;
if (CS.isIndirectCall() &&
CanReachAliveNodes(CS.getCalleeNode(), Alive, Visited, IgnoreGlobals))
return true;
for (unsigned i = 0, e = CS.getNumPtrArgs(); i != e; ++i)
if (CanReachAliveNodes(CS.getPtrArg(i).getNode(), Alive, Visited,
IgnoreGlobals))
return true;
return false;
}
// removeDeadNodes - Use a more powerful reachability analysis to eliminate
// subgraphs that are unreachable. This often occurs because the data
// structure doesn't "escape" into it's caller, and thus should be eliminated
// from the caller's graph entirely. This is only appropriate to use when
// inlining graphs.
//
void DSGraph::removeDeadNodes(unsigned Flags) {
DEBUG(AssertGraphOK(); GlobalsGraph->AssertGraphOK());
// Reduce the amount of work we have to do... remove dummy nodes left over by
// merging...
removeTriviallyDeadNodes();
// FIXME: Merge nontrivially identical call nodes...
// Alive - a set that holds all nodes found to be reachable/alive.
hash_set<DSNode*> Alive;
std::vector<std::pair<Value*, DSNode*> > GlobalNodes;
// Mark all nodes reachable by (non-global) scalar nodes as alive...
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 {
// Check to see if this is a worthless node generated for non-pointer
// values, such as integers. Consider an addition of long types: A+B.
// Assuming we can track all uses of the value in this context, and it is
// NOT used as a pointer, we can delete the node. We will be able to
// detect this situation if the node pointed to ONLY has Unknown bit set
// in the node. In this case, the node is not incomplete, does not point
// to any other nodes (no mod/ref bits set), and is therefore
// uninteresting for data structure analysis. If we run across one of
// these, prune the scalar pointing to it.
//
DSNode *N = I->second.getNode();
if (N->getNodeFlags() == DSNode::UnknownNode && !isa<Argument>(I->first)){
ScalarMap.erase(I++);
} else {
I->second.getNode()->markReachableNodes(Alive);
++I;
}
}
// The return value is alive as well...
for (ReturnNodesTy::iterator I = ReturnNodes.begin(), E = ReturnNodes.end();
I != E; ++I)
I->second.getNode()->markReachableNodes(Alive);
// Mark any nodes reachable by primary calls as alive...
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());
do {
Visited.clear();
// If any global node points to a non-global that is "alive", the global is
// "alive" as well... Remove it from the GlobalNodes list so we only have
// unreachable globals in the list.
//
Iterate = false;
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] &&
(AuxFunctionCalls[i].isIndirectCall()
|| CallSiteUsesAliveArgs(AuxFunctionCalls[i], Alive, Visited,
Flags & DSGraph::RemoveUnreachableGlobals))) {
AuxFunctionCalls[i].markReachableNodes(Alive);
AuxFCallsAlive[i] = true;
Iterate = true;
}
} while (Iterate);
// 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??");
// 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 can be removed. Loop over all nodes, eliminating completely
// unreachable nodes.
//
std::vector<DSNode*> DeadNodes;
DeadNodes.reserve(Nodes.size());
for (unsigned i = 0; i != Nodes.size(); ++i)
if (!Alive.count(Nodes[i])) {
DSNode *N = Nodes[i];
Nodes[i--] = Nodes.back(); // move node to end of vector
Nodes.pop_back(); // Erase node from alive list.
DeadNodes.push_back(N);
N->dropAllReferences();
} else {
assert(Nodes[i]->getForwardNode() == 0 && "Alive forwarded node?");
}
// 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);
}
// Delete all dead nodes now since their referrer counts are zero.
for (unsigned i = 0, e = DeadNodes.size(); i != e; ++i)
delete DeadNodes[i];
DEBUG(AssertGraphOK(); GlobalsGraph->AssertGraphOK());
}
void DSGraph::AssertGraphOK() const {
for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
Nodes[i]->assertOK();
for (ScalarMapTy::const_iterator I = ScalarMap.begin(),
E = ScalarMap.end(); I != E; ++I) {
assert(I->second.getNode() && "Null node in scalarmap!");
AssertNodeInGraph(I->second.getNode());
if (GlobalValue *GV = dyn_cast<GlobalValue>(I->first)) {
assert(I->second.getNode()->isGlobalNode() &&
"Global points to node, but node isn't global?");
AssertNodeContainsGlobal(I->second.getNode(), GV);
}
}
AssertCallNodesInGraph();
AssertAuxCallNodesInGraph();
}
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