llvm-6502/lib/Analysis/DataStructure/Local.cpp
Chris Lattner 448f4949dc Don't create a new node for every reference to a global. This caused a huge
node explosion that doesn't help anything at all.  In previous versions of
the representation this DID help, but not anymore.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4249 91177308-0d34-0410-b5e6-96231b3b80d8
2002-10-21 13:51:30 +00:00

415 lines
15 KiB
C++

//===- Local.cpp - Compute a local data structure graph for a function ----===//
//
// Compute the local version of the data structure graph for a function. The
// external interface to this file is the DSGraph constructor.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/DSGraph.h"
#include "llvm/Analysis/DataStructure.h"
#include "llvm/iMemory.h"
#include "llvm/iTerminators.h"
#include "llvm/iPHINode.h"
#include "llvm/iOther.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Target/TargetData.h"
#include "Support/Statistic.h"
// FIXME: This should eventually be a FunctionPass that is automatically
// aggregated into a Pass.
//
#include "llvm/Module.h"
using std::map;
using std::vector;
static RegisterAnalysis<LocalDataStructures>
X("datastructure", "Local Data Structure Analysis");
using namespace DataStructureAnalysis;
namespace DataStructureAnalysis {
// FIXME: Do something smarter with target data!
TargetData TD("temp-td");
unsigned PointerSize(TD.getPointerSize());
// isPointerType - Return true if this type is big enough to hold a pointer.
bool isPointerType(const Type *Ty) {
if (isa<PointerType>(Ty))
return true;
else if (Ty->isPrimitiveType() && Ty->isInteger())
return Ty->getPrimitiveSize() >= PointerSize;
return false;
}
}
namespace {
//===--------------------------------------------------------------------===//
// GraphBuilder Class
//===--------------------------------------------------------------------===//
//
/// This class is the builder class that constructs the local data structure
/// graph by performing a single pass over the function in question.
///
class GraphBuilder : InstVisitor<GraphBuilder> {
DSGraph &G;
vector<DSNode*> &Nodes;
DSNodeHandle &RetNode; // Node that gets returned...
map<Value*, DSNodeHandle> &ValueMap;
vector<DSCallSite> &FunctionCalls;
public:
GraphBuilder(DSGraph &g, vector<DSNode*> &nodes, DSNodeHandle &retNode,
map<Value*, DSNodeHandle> &vm,
vector<DSCallSite> &fc)
: G(g), Nodes(nodes), RetNode(retNode), ValueMap(vm), FunctionCalls(fc) {
// Create scalar nodes for all pointer arguments...
for (Function::aiterator I = G.getFunction().abegin(),
E = G.getFunction().aend(); I != E; ++I)
if (isPointerType(I->getType()))
getValueDest(*I);
visit(G.getFunction()); // Single pass over the function
// Not inlining, only eliminate trivially dead nodes.
G.removeTriviallyDeadNodes();
}
private:
// Visitor functions, used to handle each instruction type we encounter...
friend class InstVisitor<GraphBuilder>;
void visitMallocInst(MallocInst &MI) { handleAlloc(MI, DSNode::NewNode); }
void visitAllocaInst(AllocaInst &AI) { handleAlloc(AI, DSNode::AllocaNode);}
void handleAlloc(AllocationInst &AI, DSNode::NodeTy NT);
void visitPHINode(PHINode &PN);
void visitGetElementPtrInst(GetElementPtrInst &GEP);
void visitReturnInst(ReturnInst &RI);
void visitLoadInst(LoadInst &LI);
void visitStoreInst(StoreInst &SI);
void visitCallInst(CallInst &CI);
void visitSetCondInst(SetCondInst &SCI) {} // SetEQ & friends are ignored
void visitFreeInst(FreeInst &FI) {} // Ignore free instructions
void visitCastInst(CastInst &CI);
void visitInstruction(Instruction &I) {}
private:
// Helper functions used to implement the visitation functions...
/// createNode - Create a new DSNode, ensuring that it is properly added to
/// the graph.
///
DSNode *createNode(DSNode::NodeTy NodeType, const Type *Ty);
/// getValueNode - Return a DSNode that corresponds the the specified LLVM
/// value. This either returns the already existing node, or creates a new
/// one and adds it to the graph, if none exists.
///
DSNodeHandle getValueNode(Value &V);
/// getValueDest - Return the DSNode that the actual value points to. This
/// is basically the same thing as: getLink(getValueNode(V), 0)
///
DSNodeHandle &getValueDest(Value &V);
/// getGlobalNode - Just like getValueNode, except the global node itself is
/// returned, not a scalar node pointing to a global.
///
DSNodeHandle &getGlobalNode(GlobalValue &V);
/// getLink - This method is used to return the specified link in the
/// specified node if one exists. If a link does not already exist (it's
/// null), then we create a new node, link it, then return it. We must
/// specify the type of the Node field we are accessing so that we know what
/// type should be linked to if we need to create a new node.
///
DSNodeHandle &getLink(const DSNodeHandle &Node, unsigned Link,
const Type *FieldTy);
};
}
//===----------------------------------------------------------------------===//
// DSGraph constructor - Simply use the GraphBuilder to construct the local
// graph.
DSGraph::DSGraph(Function &F) : Func(&F) {
// Use the graph builder to construct the local version of the graph
GraphBuilder B(*this, Nodes, RetNode, ValueMap, FunctionCalls);
markIncompleteNodes();
}
//===----------------------------------------------------------------------===//
// Helper method implementations...
//
// createNode - Create a new DSNode, ensuring that it is properly added to the
// graph.
//
DSNode *GraphBuilder::createNode(DSNode::NodeTy NodeType, const Type *Ty) {
DSNode *N = new DSNode(NodeType, Ty);
Nodes.push_back(N);
return N;
}
// getGlobalNode - Just like getValueNode, except the global node itself is
// returned, not a scalar node pointing to a global.
//
DSNodeHandle &GraphBuilder::getGlobalNode(GlobalValue &V) {
DSNodeHandle &NH = ValueMap[&V];
if (NH.getNode()) return NH; // Already have a node? Just return it...
// Create a new global node for this global variable...
DSNode *G = createNode(DSNode::GlobalNode, V.getType()->getElementType());
G->addGlobal(&V);
// If this node has outgoing edges, make sure to recycle the same node for
// each use. For functions and other global variables, this is unneccesary,
// so avoid excessive merging by cloning these nodes on demand.
//
NH.setNode(G);
return NH;
}
// getValueNode - Return a DSNode that corresponds the the specified LLVM value.
// This either returns the already existing node, or creates a new one and adds
// it to the graph, if none exists.
//
DSNodeHandle GraphBuilder::getValueNode(Value &V) {
assert(isPointerType(V.getType()) && "Should only use pointer scalars!");
DSNodeHandle &NH = ValueMap[&V];
if (NH.getNode()) return NH; // Already have a node? Just return it...
// Otherwise we need to create a new scalar node...
DSNode *N = createNode(DSNode::ScalarNode, V.getType());
// If this is a global value, create the global pointed to.
if (GlobalValue *GV = dyn_cast<GlobalValue>(&V)) {
N->addEdgeTo(0, getGlobalNode(*GV));
return DSNodeHandle(N, 0);
} else {
NH.setOffset(0);
NH.setNode(N);
}
return NH;
}
/// getValueDest - Return the DSNode that the actual value points to. This
/// is basically the same thing as: getLink(getValueNode(V), 0)
///
DSNodeHandle &GraphBuilder::getValueDest(Value &V) {
return getLink(getValueNode(V), 0, V.getType());
}
/// getLink - This method is used to return the specified link in the
/// specified node if one exists. If a link does not already exist (it's
/// null), then we create a new node, link it, then return it. We must
/// specify the type of the Node field we are accessing so that we know what
/// type should be linked to if we need to create a new node.
///
DSNodeHandle &GraphBuilder::getLink(const DSNodeHandle &node,
unsigned LinkNo, const Type *FieldTy) {
DSNodeHandle &Node = const_cast<DSNodeHandle&>(node);
DSNodeHandle *Link = Node.getLink(LinkNo);
if (Link) return *Link;
// If the link hasn't been created yet, make and return a new shadow node of
// the appropriate type for FieldTy...
//
// If we are indexing with a typed pointer, then the thing we are pointing
// to is of the pointed type. If we are pointing to it with an integer
// (because of cast to an integer), we represent it with a void type.
//
const Type *ReqTy;
if (const PointerType *Ptr = dyn_cast<PointerType>(FieldTy))
ReqTy = Ptr->getElementType();
else
ReqTy = Type::VoidTy;
DSNode *N = createNode(DSNode::ShadowNode, ReqTy);
Node.setLink(LinkNo, N);
return *Node.getLink(LinkNo);
}
//===----------------------------------------------------------------------===//
// Specific instruction type handler implementations...
//
/// Alloca & Malloc instruction implementation - Simply create a new memory
/// object, pointing the scalar to it.
///
void GraphBuilder::handleAlloc(AllocationInst &AI, DSNode::NodeTy NodeType) {
//DSNode *New = createNode(NodeType, Type::VoidTy);
DSNode *New = createNode(NodeType, AI.getAllocatedType());
// Make the scalar point to the new node...
getValueNode(AI).addEdgeTo(New);
}
// PHINode - Make the scalar for the PHI node point to all of the things the
// incoming values point to... which effectively causes them to be merged.
//
void GraphBuilder::visitPHINode(PHINode &PN) {
if (!isPointerType(PN.getType())) return; // Only pointer PHIs
DSNodeHandle &ScalarDest = getValueDest(PN);
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
if (!isa<ConstantPointerNull>(PN.getIncomingValue(i)))
ScalarDest.mergeWith(getValueDest(*PN.getIncomingValue(i)));
}
void GraphBuilder::visitGetElementPtrInst(GetElementPtrInst &GEP) {
DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
unsigned Offset = 0;
const Type *CurTy = GEP.getOperand(0)->getType();
for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i)
if (GEP.getOperand(i)->getType() == Type::LongTy) {
// Get the type indexing into...
const SequentialType *STy = cast<SequentialType>(CurTy);
CurTy = STy->getElementType();
if (ConstantSInt *CS = dyn_cast<ConstantSInt>(GEP.getOperand(i))) {
if (isa<PointerType>(STy))
std::cerr << "Pointer indexing not handled yet!\n";
else
Offset += CS->getValue()*TD.getTypeSize(CurTy);
} else {
// Variable index into a node. We must merge all of the elements of the
// sequential type here.
if (isa<PointerType>(STy))
std::cerr << "Pointer indexing not handled yet!\n";
else {
const ArrayType *ATy = cast<ArrayType>(STy);
unsigned ElSize = TD.getTypeSize(CurTy);
DSNode *N = Value.getNode();
assert(N && "Value must have a node!");
unsigned RawOffset = Offset+Value.getOffset();
// Loop over all of the elements of the array, merging them into the
// zero'th element.
for (unsigned i = 1, e = ATy->getNumElements(); i != e; ++i)
// Merge all of the byte components of this array element
for (unsigned j = 0; j != ElSize; ++j)
N->mergeIndexes(RawOffset+j, RawOffset+i*ElSize+j);
}
}
} else if (GEP.getOperand(i)->getType() == Type::UByteTy) {
unsigned FieldNo = cast<ConstantUInt>(GEP.getOperand(i))->getValue();
const StructType *STy = cast<StructType>(CurTy);
Offset += TD.getStructLayout(STy)->MemberOffsets[FieldNo];
CurTy = STy->getContainedType(FieldNo);
}
// Add in the offset calculated...
Value.setOffset(Value.getOffset()+Offset);
// Value is now the pointer we want to GEP to be...
getValueNode(GEP).addEdgeTo(Value);
}
void GraphBuilder::visitLoadInst(LoadInst &LI) {
DSNodeHandle &Ptr = getValueDest(*LI.getOperand(0));
Ptr.getNode()->NodeType |= DSNode::Read;
if (isPointerType(LI.getType()))
getValueNode(LI).addEdgeTo(getLink(Ptr, 0, LI.getType()));
}
void GraphBuilder::visitStoreInst(StoreInst &SI) {
DSNodeHandle &Dest = getValueDest(*SI.getOperand(1));
Dest.getNode()->NodeType |= DSNode::Modified;
// Avoid adding edges from null, or processing non-"pointer" stores
if (isPointerType(SI.getOperand(0)->getType()) &&
!isa<ConstantPointerNull>(SI.getOperand(0))) {
Dest.addEdgeTo(getValueDest(*SI.getOperand(0)));
}
}
void GraphBuilder::visitReturnInst(ReturnInst &RI) {
if (RI.getNumOperands() && isPointerType(RI.getOperand(0)->getType()) &&
!isa<ConstantPointerNull>(RI.getOperand(0))) {
DSNodeHandle &Value = getValueDest(*RI.getOperand(0));
Value.mergeWith(RetNode);
RetNode = Value;
}
}
void GraphBuilder::visitCallInst(CallInst &CI) {
// Set up the return value...
DSNodeHandle RetVal;
if (isPointerType(CI.getType()))
RetVal = getLink(getValueNode(CI), 0, CI.getType());
DSNodeHandle Callee;
// Special case for a direct call, avoid creating spurious scalar node...
if (GlobalValue *GV = dyn_cast<GlobalValue>(CI.getOperand(0)))
Callee = getGlobalNode(*GV);
else
Callee = getLink(getValueNode(*CI.getOperand(0)), 0,
CI.getOperand(0)->getType());
std::vector<DSNodeHandle> Args;
Args.reserve(CI.getNumOperands()-1);
// Calculate the arguments vector...
for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
if (isPointerType(CI.getOperand(i)->getType()))
Args.push_back(getLink(getValueNode(*CI.getOperand(i)), 0,
CI.getOperand(i)->getType()));
// Add a new function call entry...
FunctionCalls.push_back(DSCallSite(CI, RetVal, Callee, Args));
}
/// Handle casts...
void GraphBuilder::visitCastInst(CastInst &CI) {
if (isPointerType(CI.getType()) && isPointerType(CI.getOperand(0)->getType()))
getValueNode(CI).addEdgeTo(getLink(getValueNode(*CI.getOperand(0)), 0,
CI.getOperand(0)->getType()));
}
//===----------------------------------------------------------------------===//
// LocalDataStructures Implementation
//===----------------------------------------------------------------------===//
// releaseMemory - If the pass pipeline is done with this pass, we can release
// our memory... here...
//
void LocalDataStructures::releaseMemory() {
for (std::map<const 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;
}