llvm-6502/lib/VMCore/Metadata.cpp
Benjamin Kramer 611afc0620 Cache the hash value of the operands in the MDNode.
FoldingSet is implemented as a chained hash table. When there is a hash
collision during insertion, which is common as we fill the table until a
load factor of 2.0 is hit, we walk the chained elements, comparing every
operand with the new element's operands. This can be very expensive if the
MDNode has many operands.

We sacrifice a word of space in MDNode to cache the full hash value, reducing
compares on collision to a minimum. MDNode grows from 28 to 32 bytes + operands
on x86. On x86_64 the new bits fit nicely into existing padding, not growing
the struct at all.

The actual speedup depends a lot on the test case and is typically between
1% and 2% for C++ code with clang -c -O0 -g.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154497 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-11 14:06:54 +00:00

592 lines
19 KiB
C++

//===-- Metadata.cpp - Implement Metadata classes -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Metadata classes.
//
//===----------------------------------------------------------------------===//
#include "llvm/Metadata.h"
#include "LLVMContextImpl.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/Instruction.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/STLExtras.h"
#include "SymbolTableListTraitsImpl.h"
#include "llvm/Support/LeakDetector.h"
#include "llvm/Support/ValueHandle.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// MDString implementation.
//
void MDString::anchor() { }
MDString::MDString(LLVMContext &C)
: Value(Type::getMetadataTy(C), Value::MDStringVal) {}
MDString *MDString::get(LLVMContext &Context, StringRef Str) {
LLVMContextImpl *pImpl = Context.pImpl;
StringMapEntry<Value*> &Entry =
pImpl->MDStringCache.GetOrCreateValue(Str);
Value *&S = Entry.getValue();
if (!S) S = new MDString(Context);
S->setValueName(&Entry);
return cast<MDString>(S);
}
//===----------------------------------------------------------------------===//
// MDNodeOperand implementation.
//
// Use CallbackVH to hold MDNode operands.
namespace llvm {
class MDNodeOperand : public CallbackVH {
MDNode *getParent() {
MDNodeOperand *Cur = this;
while (Cur->getValPtrInt() != 1)
--Cur;
assert(Cur->getValPtrInt() == 1 &&
"Couldn't find the beginning of the operand list!");
return reinterpret_cast<MDNode*>(Cur) - 1;
}
public:
MDNodeOperand(Value *V) : CallbackVH(V) {}
~MDNodeOperand() {}
void set(Value *V) { this->setValPtr(V); }
/// setAsFirstOperand - Accessor method to mark the operand as the first in
/// the list.
void setAsFirstOperand(unsigned V) { this->setValPtrInt(V); }
virtual void deleted();
virtual void allUsesReplacedWith(Value *NV);
};
} // end namespace llvm.
void MDNodeOperand::deleted() {
getParent()->replaceOperand(this, 0);
}
void MDNodeOperand::allUsesReplacedWith(Value *NV) {
getParent()->replaceOperand(this, NV);
}
//===----------------------------------------------------------------------===//
// MDNode implementation.
//
/// getOperandPtr - Helper function to get the MDNodeOperand's coallocated on
/// the end of the MDNode.
static MDNodeOperand *getOperandPtr(MDNode *N, unsigned Op) {
// Use <= instead of < to permit a one-past-the-end address.
assert(Op <= N->getNumOperands() && "Invalid operand number");
return reinterpret_cast<MDNodeOperand*>(N+1)+Op;
}
void MDNode::replaceOperandWith(unsigned i, Value *Val) {
MDNodeOperand *Op = getOperandPtr(this, i);
replaceOperand(Op, Val);
}
MDNode::MDNode(LLVMContext &C, ArrayRef<Value*> Vals, bool isFunctionLocal)
: Value(Type::getMetadataTy(C), Value::MDNodeVal) {
NumOperands = Vals.size();
if (isFunctionLocal)
setValueSubclassData(getSubclassDataFromValue() | FunctionLocalBit);
// Initialize the operand list, which is co-allocated on the end of the node.
unsigned i = 0;
for (MDNodeOperand *Op = getOperandPtr(this, 0), *E = Op+NumOperands;
Op != E; ++Op, ++i) {
new (Op) MDNodeOperand(Vals[i]);
// Mark the first MDNodeOperand as being the first in the list of operands.
if (i == 0)
Op->setAsFirstOperand(1);
}
}
/// ~MDNode - Destroy MDNode.
MDNode::~MDNode() {
assert((getSubclassDataFromValue() & DestroyFlag) != 0 &&
"Not being destroyed through destroy()?");
LLVMContextImpl *pImpl = getType()->getContext().pImpl;
if (isNotUniqued()) {
pImpl->NonUniquedMDNodes.erase(this);
} else {
pImpl->MDNodeSet.RemoveNode(this);
}
// Destroy the operands.
for (MDNodeOperand *Op = getOperandPtr(this, 0), *E = Op+NumOperands;
Op != E; ++Op)
Op->~MDNodeOperand();
}
static const Function *getFunctionForValue(Value *V) {
if (!V) return NULL;
if (Instruction *I = dyn_cast<Instruction>(V)) {
BasicBlock *BB = I->getParent();
return BB ? BB->getParent() : 0;
}
if (Argument *A = dyn_cast<Argument>(V))
return A->getParent();
if (BasicBlock *BB = dyn_cast<BasicBlock>(V))
return BB->getParent();
if (MDNode *MD = dyn_cast<MDNode>(V))
return MD->getFunction();
return NULL;
}
#ifndef NDEBUG
static const Function *assertLocalFunction(const MDNode *N) {
if (!N->isFunctionLocal()) return 0;
// FIXME: This does not handle cyclic function local metadata.
const Function *F = 0, *NewF = 0;
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
if (Value *V = N->getOperand(i)) {
if (MDNode *MD = dyn_cast<MDNode>(V))
NewF = assertLocalFunction(MD);
else
NewF = getFunctionForValue(V);
}
if (F == 0)
F = NewF;
else
assert((NewF == 0 || F == NewF) &&"inconsistent function-local metadata");
}
return F;
}
#endif
// getFunction - If this metadata is function-local and recursively has a
// function-local operand, return the first such operand's parent function.
// Otherwise, return null. getFunction() should not be used for performance-
// critical code because it recursively visits all the MDNode's operands.
const Function *MDNode::getFunction() const {
#ifndef NDEBUG
return assertLocalFunction(this);
#else
if (!isFunctionLocal()) return NULL;
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
if (const Function *F = getFunctionForValue(getOperand(i)))
return F;
return NULL;
#endif
}
// destroy - Delete this node. Only when there are no uses.
void MDNode::destroy() {
setValueSubclassData(getSubclassDataFromValue() | DestroyFlag);
// Placement delete, the free the memory.
this->~MDNode();
free(this);
}
/// isFunctionLocalValue - Return true if this is a value that would require a
/// function-local MDNode.
static bool isFunctionLocalValue(Value *V) {
return isa<Instruction>(V) || isa<Argument>(V) || isa<BasicBlock>(V) ||
(isa<MDNode>(V) && cast<MDNode>(V)->isFunctionLocal());
}
MDNode *MDNode::getMDNode(LLVMContext &Context, ArrayRef<Value*> Vals,
FunctionLocalness FL, bool Insert) {
LLVMContextImpl *pImpl = Context.pImpl;
// Add all the operand pointers. Note that we don't have to add the
// isFunctionLocal bit because that's implied by the operands.
// Note that if the operands are later nulled out, the node will be
// removed from the uniquing map.
FoldingSetNodeID ID;
for (unsigned i = 0; i != Vals.size(); ++i)
ID.AddPointer(Vals[i]);
void *InsertPoint;
MDNode *N = pImpl->MDNodeSet.FindNodeOrInsertPos(ID, InsertPoint);
if (N || !Insert)
return N;
bool isFunctionLocal = false;
switch (FL) {
case FL_Unknown:
for (unsigned i = 0; i != Vals.size(); ++i) {
Value *V = Vals[i];
if (!V) continue;
if (isFunctionLocalValue(V)) {
isFunctionLocal = true;
break;
}
}
break;
case FL_No:
isFunctionLocal = false;
break;
case FL_Yes:
isFunctionLocal = true;
break;
}
// Coallocate space for the node and Operands together, then placement new.
void *Ptr = malloc(sizeof(MDNode)+Vals.size()*sizeof(MDNodeOperand));
N = new (Ptr) MDNode(Context, Vals, isFunctionLocal);
// Cache the operand hash.
N->Hash = ID.ComputeHash();
// InsertPoint will have been set by the FindNodeOrInsertPos call.
pImpl->MDNodeSet.InsertNode(N, InsertPoint);
return N;
}
MDNode *MDNode::get(LLVMContext &Context, ArrayRef<Value*> Vals) {
return getMDNode(Context, Vals, FL_Unknown);
}
MDNode *MDNode::getWhenValsUnresolved(LLVMContext &Context,
ArrayRef<Value*> Vals,
bool isFunctionLocal) {
return getMDNode(Context, Vals, isFunctionLocal ? FL_Yes : FL_No);
}
MDNode *MDNode::getIfExists(LLVMContext &Context, ArrayRef<Value*> Vals) {
return getMDNode(Context, Vals, FL_Unknown, false);
}
MDNode *MDNode::getTemporary(LLVMContext &Context, ArrayRef<Value*> Vals) {
MDNode *N =
(MDNode *)malloc(sizeof(MDNode)+Vals.size()*sizeof(MDNodeOperand));
N = new (N) MDNode(Context, Vals, FL_No);
N->setValueSubclassData(N->getSubclassDataFromValue() |
NotUniquedBit);
LeakDetector::addGarbageObject(N);
return N;
}
void MDNode::deleteTemporary(MDNode *N) {
assert(N->use_empty() && "Temporary MDNode has uses!");
assert(!N->getContext().pImpl->MDNodeSet.RemoveNode(N) &&
"Deleting a non-temporary uniqued node!");
assert(!N->getContext().pImpl->NonUniquedMDNodes.erase(N) &&
"Deleting a non-temporary non-uniqued node!");
assert((N->getSubclassDataFromValue() & NotUniquedBit) &&
"Temporary MDNode does not have NotUniquedBit set!");
assert((N->getSubclassDataFromValue() & DestroyFlag) == 0 &&
"Temporary MDNode has DestroyFlag set!");
LeakDetector::removeGarbageObject(N);
N->destroy();
}
/// getOperand - Return specified operand.
Value *MDNode::getOperand(unsigned i) const {
return *getOperandPtr(const_cast<MDNode*>(this), i);
}
void MDNode::Profile(FoldingSetNodeID &ID) const {
// Add all the operand pointers. Note that we don't have to add the
// isFunctionLocal bit because that's implied by the operands.
// Note that if the operands are later nulled out, the node will be
// removed from the uniquing map.
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
ID.AddPointer(getOperand(i));
}
void MDNode::setIsNotUniqued() {
setValueSubclassData(getSubclassDataFromValue() | NotUniquedBit);
LLVMContextImpl *pImpl = getType()->getContext().pImpl;
pImpl->NonUniquedMDNodes.insert(this);
}
// Replace value from this node's operand list.
void MDNode::replaceOperand(MDNodeOperand *Op, Value *To) {
Value *From = *Op;
// If is possible that someone did GV->RAUW(inst), replacing a global variable
// with an instruction or some other function-local object. If this is a
// non-function-local MDNode, it can't point to a function-local object.
// Handle this case by implicitly dropping the MDNode reference to null.
// Likewise if the MDNode is function-local but for a different function.
if (To && isFunctionLocalValue(To)) {
if (!isFunctionLocal())
To = 0;
else {
const Function *F = getFunction();
const Function *FV = getFunctionForValue(To);
// Metadata can be function-local without having an associated function.
// So only consider functions to have changed if non-null.
if (F && FV && F != FV)
To = 0;
}
}
if (From == To)
return;
// Update the operand.
Op->set(To);
// If this node is already not being uniqued (because one of the operands
// already went to null), then there is nothing else to do here.
if (isNotUniqued()) return;
LLVMContextImpl *pImpl = getType()->getContext().pImpl;
// Remove "this" from the context map. FoldingSet doesn't have to reprofile
// this node to remove it, so we don't care what state the operands are in.
pImpl->MDNodeSet.RemoveNode(this);
// If we are dropping an argument to null, we choose to not unique the MDNode
// anymore. This commonly occurs during destruction, and uniquing these
// brings little reuse. Also, this means we don't need to include
// isFunctionLocal bits in FoldingSetNodeIDs for MDNodes.
if (To == 0) {
setIsNotUniqued();
return;
}
// Now that the node is out of the folding set, get ready to reinsert it.
// First, check to see if another node with the same operands already exists
// in the set. If so, then this node is redundant.
FoldingSetNodeID ID;
Profile(ID);
void *InsertPoint;
if (MDNode *N = pImpl->MDNodeSet.FindNodeOrInsertPos(ID, InsertPoint)) {
replaceAllUsesWith(N);
destroy();
return;
}
// Cache the operand hash.
Hash = ID.ComputeHash();
// InsertPoint will have been set by the FindNodeOrInsertPos call.
pImpl->MDNodeSet.InsertNode(this, InsertPoint);
// If this MDValue was previously function-local but no longer is, clear
// its function-local flag.
if (isFunctionLocal() && !isFunctionLocalValue(To)) {
bool isStillFunctionLocal = false;
for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
Value *V = getOperand(i);
if (!V) continue;
if (isFunctionLocalValue(V)) {
isStillFunctionLocal = true;
break;
}
}
if (!isStillFunctionLocal)
setValueSubclassData(getSubclassDataFromValue() & ~FunctionLocalBit);
}
}
//===----------------------------------------------------------------------===//
// NamedMDNode implementation.
//
static SmallVector<TrackingVH<MDNode>, 4> &getNMDOps(void *Operands) {
return *(SmallVector<TrackingVH<MDNode>, 4>*)Operands;
}
NamedMDNode::NamedMDNode(const Twine &N)
: Name(N.str()), Parent(0),
Operands(new SmallVector<TrackingVH<MDNode>, 4>()) {
}
NamedMDNode::~NamedMDNode() {
dropAllReferences();
delete &getNMDOps(Operands);
}
/// getNumOperands - Return number of NamedMDNode operands.
unsigned NamedMDNode::getNumOperands() const {
return (unsigned)getNMDOps(Operands).size();
}
/// getOperand - Return specified operand.
MDNode *NamedMDNode::getOperand(unsigned i) const {
assert(i < getNumOperands() && "Invalid Operand number!");
return dyn_cast<MDNode>(&*getNMDOps(Operands)[i]);
}
/// addOperand - Add metadata Operand.
void NamedMDNode::addOperand(MDNode *M) {
assert(!M->isFunctionLocal() &&
"NamedMDNode operands must not be function-local!");
getNMDOps(Operands).push_back(TrackingVH<MDNode>(M));
}
/// eraseFromParent - Drop all references and remove the node from parent
/// module.
void NamedMDNode::eraseFromParent() {
getParent()->eraseNamedMetadata(this);
}
/// dropAllReferences - Remove all uses and clear node vector.
void NamedMDNode::dropAllReferences() {
getNMDOps(Operands).clear();
}
/// getName - Return a constant reference to this named metadata's name.
StringRef NamedMDNode::getName() const {
return StringRef(Name);
}
//===----------------------------------------------------------------------===//
// Instruction Metadata method implementations.
//
void Instruction::setMetadata(StringRef Kind, MDNode *Node) {
if (Node == 0 && !hasMetadata()) return;
setMetadata(getContext().getMDKindID(Kind), Node);
}
MDNode *Instruction::getMetadataImpl(StringRef Kind) const {
return getMetadataImpl(getContext().getMDKindID(Kind));
}
/// setMetadata - Set the metadata of of the specified kind to the specified
/// node. This updates/replaces metadata if already present, or removes it if
/// Node is null.
void Instruction::setMetadata(unsigned KindID, MDNode *Node) {
if (Node == 0 && !hasMetadata()) return;
// Handle 'dbg' as a special case since it is not stored in the hash table.
if (KindID == LLVMContext::MD_dbg) {
DbgLoc = DebugLoc::getFromDILocation(Node);
return;
}
// Handle the case when we're adding/updating metadata on an instruction.
if (Node) {
LLVMContextImpl::MDMapTy &Info = getContext().pImpl->MetadataStore[this];
assert(!Info.empty() == hasMetadataHashEntry() &&
"HasMetadata bit is wonked");
if (Info.empty()) {
setHasMetadataHashEntry(true);
} else {
// Handle replacement of an existing value.
for (unsigned i = 0, e = Info.size(); i != e; ++i)
if (Info[i].first == KindID) {
Info[i].second = Node;
return;
}
}
// No replacement, just add it to the list.
Info.push_back(std::make_pair(KindID, Node));
return;
}
// Otherwise, we're removing metadata from an instruction.
assert((hasMetadataHashEntry() ==
getContext().pImpl->MetadataStore.count(this)) &&
"HasMetadata bit out of date!");
if (!hasMetadataHashEntry())
return; // Nothing to remove!
LLVMContextImpl::MDMapTy &Info = getContext().pImpl->MetadataStore[this];
// Common case is removing the only entry.
if (Info.size() == 1 && Info[0].first == KindID) {
getContext().pImpl->MetadataStore.erase(this);
setHasMetadataHashEntry(false);
return;
}
// Handle removal of an existing value.
for (unsigned i = 0, e = Info.size(); i != e; ++i)
if (Info[i].first == KindID) {
Info[i] = Info.back();
Info.pop_back();
assert(!Info.empty() && "Removing last entry should be handled above");
return;
}
// Otherwise, removing an entry that doesn't exist on the instruction.
}
MDNode *Instruction::getMetadataImpl(unsigned KindID) const {
// Handle 'dbg' as a special case since it is not stored in the hash table.
if (KindID == LLVMContext::MD_dbg)
return DbgLoc.getAsMDNode(getContext());
if (!hasMetadataHashEntry()) return 0;
LLVMContextImpl::MDMapTy &Info = getContext().pImpl->MetadataStore[this];
assert(!Info.empty() && "bit out of sync with hash table");
for (LLVMContextImpl::MDMapTy::iterator I = Info.begin(), E = Info.end();
I != E; ++I)
if (I->first == KindID)
return I->second;
return 0;
}
void Instruction::getAllMetadataImpl(SmallVectorImpl<std::pair<unsigned,
MDNode*> > &Result) const {
Result.clear();
// Handle 'dbg' as a special case since it is not stored in the hash table.
if (!DbgLoc.isUnknown()) {
Result.push_back(std::make_pair((unsigned)LLVMContext::MD_dbg,
DbgLoc.getAsMDNode(getContext())));
if (!hasMetadataHashEntry()) return;
}
assert(hasMetadataHashEntry() &&
getContext().pImpl->MetadataStore.count(this) &&
"Shouldn't have called this");
const LLVMContextImpl::MDMapTy &Info =
getContext().pImpl->MetadataStore.find(this)->second;
assert(!Info.empty() && "Shouldn't have called this");
Result.append(Info.begin(), Info.end());
// Sort the resulting array so it is stable.
if (Result.size() > 1)
array_pod_sort(Result.begin(), Result.end());
}
void Instruction::
getAllMetadataOtherThanDebugLocImpl(SmallVectorImpl<std::pair<unsigned,
MDNode*> > &Result) const {
Result.clear();
assert(hasMetadataHashEntry() &&
getContext().pImpl->MetadataStore.count(this) &&
"Shouldn't have called this");
const LLVMContextImpl::MDMapTy &Info =
getContext().pImpl->MetadataStore.find(this)->second;
assert(!Info.empty() && "Shouldn't have called this");
Result.append(Info.begin(), Info.end());
// Sort the resulting array so it is stable.
if (Result.size() > 1)
array_pod_sort(Result.begin(), Result.end());
}
/// clearMetadataHashEntries - Clear all hashtable-based metadata from
/// this instruction.
void Instruction::clearMetadataHashEntries() {
assert(hasMetadataHashEntry() && "Caller should check");
getContext().pImpl->MetadataStore.erase(this);
setHasMetadataHashEntry(false);
}