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//===- ValueEnumerator.cpp - Number values and types for bitcode writer ---===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file implements the ValueEnumerator class.
#include "ValueEnumerator.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalIFunc.h"
#include "llvm/IR/GlobalObject.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Use.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/ValueSymbolTable.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cstddef>
#include <iterator>
#include <tuple>
using namespace llvm;
namespace {
struct OrderMap {
DenseMap<const Value *, std::pair<unsigned, bool>> IDs;
unsigned LastGlobalConstantID = 0;
unsigned LastGlobalValueID = 0;
OrderMap() = default;
bool isGlobalConstant(unsigned ID) const {
return ID <= LastGlobalConstantID;
bool isGlobalValue(unsigned ID) const {
return ID <= LastGlobalValueID && !isGlobalConstant(ID);
unsigned size() const { return IDs.size(); }
std::pair<unsigned, bool> &operator[](const Value *V) { return IDs[V]; }
std::pair<unsigned, bool> lookup(const Value *V) const {
return IDs.lookup(V);
void index(const Value *V) {
// Explicitly sequence get-size and insert-value operations to avoid UB.
unsigned ID = IDs.size() + 1;
IDs[V].first = ID;
} // end anonymous namespace
/// Look for a value that might be wrapped as metadata, e.g. a value in a
/// metadata operand. Returns nullptr for a non-wrapped input value if
/// OnlyWrapped is true, or it returns the input value as-is if false.
static const Value *skipMetadataWrapper(const Value *V, bool OnlyWrapped) {
if (const auto *MAV = dyn_cast<MetadataAsValue>(V))
if (const auto *VAM = dyn_cast<ValueAsMetadata>(MAV->getMetadata()))
return VAM->getValue();
return OnlyWrapped ? nullptr : V;
static void orderValue(const Value *V, OrderMap &OM) {
if (OM.lookup(V).first)
if (const Constant *C = dyn_cast<Constant>(V)) {
if (C->getNumOperands() && !isa<GlobalValue>(C)) {
for (const Value *Op : C->operands())
if (!isa<BasicBlock>(Op) && !isa<GlobalValue>(Op))
orderValue(Op, OM);
if (auto *CE = dyn_cast<ConstantExpr>(C))
if (CE->getOpcode() == Instruction::ShuffleVector)
orderValue(CE->getShuffleMaskForBitcode(), OM);
// Note: we cannot cache this lookup above, since inserting into the map
// changes the map's size, and thus affects the other IDs.
static OrderMap orderModule(const Module &M) {
// This needs to match the order used by ValueEnumerator::ValueEnumerator()
// and ValueEnumerator::incorporateFunction().
OrderMap OM;
// In the reader, initializers of GlobalValues are set *after* all the
// globals have been read. Rather than awkwardly modeling this behaviour
// directly in predictValueUseListOrderImpl(), just assign IDs to
// initializers of GlobalValues before GlobalValues themselves to model this
// implicitly.
for (const GlobalVariable &G : M.globals())
if (G.hasInitializer())
if (!isa<GlobalValue>(G.getInitializer()))
orderValue(G.getInitializer(), OM);
for (const GlobalAlias &A : M.aliases())
if (!isa<GlobalValue>(A.getAliasee()))
orderValue(A.getAliasee(), OM);
for (const GlobalIFunc &I : M.ifuncs())
if (!isa<GlobalValue>(I.getResolver()))
orderValue(I.getResolver(), OM);
for (const Function &F : M) {
for (const Use &U : F.operands())
if (!isa<GlobalValue>(U.get()))
orderValue(U.get(), OM);
// As constants used in metadata operands are emitted as module-level
// constants, we must order them before other operands. Also, we must order
// these before global values, as these will be read before setting the
// global values' initializers. The latter matters for constants which have
// uses towards other constants that are used as initializers.
for (const Function &F : M) {
if (F.isDeclaration())
for (const BasicBlock &BB : F)
for (const Instruction &I : BB)
for (const Value *V : I.operands()) {
if (const Value *Op = skipMetadataWrapper(V, true)) {
if ((isa<Constant>(*Op) && !isa<GlobalValue>(*Op)) ||
orderValue(Op, OM);
OM.LastGlobalConstantID = OM.size();
// Initializers of GlobalValues are processed in
// BitcodeReader::ResolveGlobalAndAliasInits(). Match the order there rather
// than ValueEnumerator, and match the code in predictValueUseListOrderImpl()
// by giving IDs in reverse order.
// Since GlobalValues never reference each other directly (just through
// initializers), their relative IDs only matter for determining order of
// uses in their initializers.
for (const Function &F : M)
orderValue(&F, OM);
for (const GlobalAlias &A : M.aliases())
orderValue(&A, OM);
for (const GlobalIFunc &I : M.ifuncs())
orderValue(&I, OM);
for (const GlobalVariable &G : M.globals())
orderValue(&G, OM);
OM.LastGlobalValueID = OM.size();
for (const Function &F : M) {
if (F.isDeclaration())
// Here we need to match the union of ValueEnumerator::incorporateFunction()
// and WriteFunction(). Basic blocks are implicitly declared before
// anything else (by declaring their size).
for (const BasicBlock &BB : F)
orderValue(&BB, OM);
for (const Argument &A : F.args())
orderValue(&A, OM);
for (const BasicBlock &BB : F)
for (const Instruction &I : BB) {
for (const Value *Op : I.operands())
if ((isa<Constant>(*Op) && !isa<GlobalValue>(*Op)) ||
orderValue(Op, OM);
if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
orderValue(SVI->getShuffleMaskForBitcode(), OM);
for (const BasicBlock &BB : F)
for (const Instruction &I : BB)
orderValue(&I, OM);
return OM;
static void predictValueUseListOrderImpl(const Value *V, const Function *F,
unsigned ID, const OrderMap &OM,
UseListOrderStack &Stack) {
// Predict use-list order for this one.
using Entry = std::pair<const Use *, unsigned>;
SmallVector<Entry, 64> List;
for (const Use &U : V->uses())
// Check if this user will be serialized.
if (OM.lookup(U.getUser()).first)
List.push_back(std::make_pair(&U, List.size()));
if (List.size() < 2)
// We may have lost some users.
bool IsGlobalValue = OM.isGlobalValue(ID);
llvm::sort(List, [&](const Entry &L, const Entry &R) {
const Use *LU = L.first;
const Use *RU = R.first;
if (LU == RU)
return false;
auto LID = OM.lookup(LU->getUser()).first;
auto RID = OM.lookup(RU->getUser()).first;
// Global values are processed in reverse order.
// Moreover, initializers of GlobalValues are set *after* all the globals
// have been read (despite having earlier IDs). Rather than awkwardly
// modeling this behaviour here, orderModule() has assigned IDs to
// initializers of GlobalValues before GlobalValues themselves.
if (OM.isGlobalValue(LID) && OM.isGlobalValue(RID))
return LID < RID;
// If ID is 4, then expect: 7 6 5 1 2 3.
if (LID < RID) {
if (RID <= ID)
if (!IsGlobalValue) // GlobalValue uses don't get reversed.
return true;
return false;
if (RID < LID) {
if (LID <= ID)
if (!IsGlobalValue) // GlobalValue uses don't get reversed.
return false;
return true;
// LID and RID are equal, so we have different operands of the same user.
// Assume operands are added in order for all instructions.
if (LID <= ID)
if (!IsGlobalValue) // GlobalValue uses don't get reversed.
return LU->getOperandNo() < RU->getOperandNo();
return LU->getOperandNo() > RU->getOperandNo();
if (llvm::is_sorted(List, [](const Entry &L, const Entry &R) {
return L.second < R.second;
// Order is already correct.
// Store the shuffle.
Stack.emplace_back(V, F, List.size());
assert(List.size() == Stack.back().Shuffle.size() && "Wrong size");
for (size_t I = 0, E = List.size(); I != E; ++I)
Stack.back().Shuffle[I] = List[I].second;
static void predictValueUseListOrder(const Value *V, const Function *F,
OrderMap &OM, UseListOrderStack &Stack) {
auto &IDPair = OM[V];
assert(IDPair.first && "Unmapped value");
if (IDPair.second)
// Already predicted.
// Do the actual prediction.
IDPair.second = true;
if (!V->use_empty() && std::next(V->use_begin()) != V->use_end())
predictValueUseListOrderImpl(V, F, IDPair.first, OM, Stack);
// Recursive descent into constants.
if (const Constant *C = dyn_cast<Constant>(V)) {
if (C->getNumOperands()) { // Visit GlobalValues.
for (const Value *Op : C->operands())
if (isa<Constant>(Op)) // Visit GlobalValues.
predictValueUseListOrder(Op, F, OM, Stack);
if (auto *CE = dyn_cast<ConstantExpr>(C))
if (CE->getOpcode() == Instruction::ShuffleVector)
predictValueUseListOrder(CE->getShuffleMaskForBitcode(), F, OM,
static UseListOrderStack predictUseListOrder(const Module &M) {
OrderMap OM = orderModule(M);
// Use-list orders need to be serialized after all the users have been added
// to a value, or else the shuffles will be incomplete. Store them per
// function in a stack.
// Aside from function order, the order of values doesn't matter much here.
UseListOrderStack Stack;
// We want to visit the functions backward now so we can list function-local
// constants in the last Function they're used in. Module-level constants
// have already been visited above.
for (auto I = M.rbegin(), E = M.rend(); I != E; ++I) {
const Function &F = *I;
if (F.isDeclaration())
for (const BasicBlock &BB : F)
predictValueUseListOrder(&BB, &F, OM, Stack);
for (const Argument &A : F.args())
predictValueUseListOrder(&A, &F, OM, Stack);
for (const BasicBlock &BB : F)
for (const Instruction &I : BB) {
for (const Value *Op : I.operands())
if (isa<Constant>(*Op) || isa<InlineAsm>(*Op)) // Visit GlobalValues.
predictValueUseListOrder(Op, &F, OM, Stack);
if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
predictValueUseListOrder(SVI->getShuffleMaskForBitcode(), &F, OM,
for (const BasicBlock &BB : F)
for (const Instruction &I : BB)
predictValueUseListOrder(&I, &F, OM, Stack);
// Visit globals last, since the module-level use-list block will be seen
// before the function bodies are processed.
for (const GlobalVariable &G : M.globals())
predictValueUseListOrder(&G, nullptr, OM, Stack);
for (const Function &F : M)
predictValueUseListOrder(&F, nullptr, OM, Stack);
for (const GlobalAlias &A : M.aliases())
predictValueUseListOrder(&A, nullptr, OM, Stack);
for (const GlobalIFunc &I : M.ifuncs())
predictValueUseListOrder(&I, nullptr, OM, Stack);
for (const GlobalVariable &G : M.globals())
if (G.hasInitializer())
predictValueUseListOrder(G.getInitializer(), nullptr, OM, Stack);
for (const GlobalAlias &A : M.aliases())
predictValueUseListOrder(A.getAliasee(), nullptr, OM, Stack);
for (const GlobalIFunc &I : M.ifuncs())
predictValueUseListOrder(I.getResolver(), nullptr, OM, Stack);
for (const Function &F : M) {
for (const Use &U : F.operands())
predictValueUseListOrder(U.get(), nullptr, OM, Stack);
return Stack;
static bool isIntOrIntVectorValue(const std::pair<const Value*, unsigned> &V) {
return V.first->getType()->isIntOrIntVectorTy();
ValueEnumerator::ValueEnumerator(const Module &M,
bool ShouldPreserveUseListOrder)
: ShouldPreserveUseListOrder(ShouldPreserveUseListOrder) {
if (ShouldPreserveUseListOrder)
UseListOrders = predictUseListOrder(M);
// Enumerate the global variables.
for (const GlobalVariable &GV : M.globals())
// Enumerate the functions.
for (const Function & F : M) {
// Enumerate the aliases.
for (const GlobalAlias &GA : M.aliases())
// Enumerate the ifuncs.
for (const GlobalIFunc &GIF : M.ifuncs())
// Remember what is the cutoff between globalvalue's and other constants.
unsigned FirstConstant = Values.size();
// Enumerate the global variable initializers and attributes.
for (const GlobalVariable &GV : M.globals()) {
if (GV.hasInitializer())
if (GV.hasAttributes())
// Enumerate the aliasees.
for (const GlobalAlias &GA : M.aliases())
// Enumerate the ifunc resolvers.
for (const GlobalIFunc &GIF : M.ifuncs())
// Enumerate any optional Function data.
for (const Function &F : M)
for (const Use &U : F.operands())
// Enumerate the metadata type.
// TODO: Move this to ValueEnumerator::EnumerateOperandType() once bitcode
// only encodes the metadata type when it's used as a value.
// Insert constants and metadata that are named at module level into the slot
// pool so that the module symbol table can refer to them...
SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
for (const GlobalVariable &GV : M.globals()) {
for (const auto &I : MDs)
// FIXME: Pass GV to EnumerateMetadata and arrange for the bitcode writer
// to write metadata to the global variable's own metadata block
// (PR28134).
EnumerateMetadata(nullptr, I.second);
// Enumerate types used by function bodies and argument lists.
for (const Function &F : M) {
for (const Argument &A : F.args())
// Enumerate metadata attached to this function.
for (const auto &I : MDs)
EnumerateMetadata(F.isDeclaration() ? nullptr : &F, I.second);
for (const BasicBlock &BB : F)
for (const Instruction &I : BB) {
for (const Use &Op : I.operands()) {
auto *MD = dyn_cast<MetadataAsValue>(&Op);
if (!MD) {
// Local metadata is enumerated during function-incorporation.
if (isa<LocalAsMetadata>(MD->getMetadata()) ||
EnumerateMetadata(&F, MD->getMetadata());
if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
if (const auto *Call = dyn_cast<CallBase>(&I))
// Enumerate metadata attached with this instruction.
for (unsigned i = 0, e = MDs.size(); i != e; ++i)
EnumerateMetadata(&F, MDs[i].second);
// Don't enumerate the location directly -- it has a special record
// type -- but enumerate its operands.
if (DILocation *L = I.getDebugLoc())
for (const Metadata *Op : L->operands())
EnumerateMetadata(&F, Op);
// Optimize constant ordering.
OptimizeConstants(FirstConstant, Values.size());
// Organize metadata ordering.
unsigned ValueEnumerator::getInstructionID(const Instruction *Inst) const {
InstructionMapType::const_iterator I = InstructionMap.find(Inst);
assert(I != InstructionMap.end() && "Instruction is not mapped!");
return I->second;
unsigned ValueEnumerator::getComdatID(const Comdat *C) const {
unsigned ComdatID = Comdats.idFor(C);
assert(ComdatID && "Comdat not found!");
return ComdatID;
void ValueEnumerator::setInstructionID(const Instruction *I) {
InstructionMap[I] = InstructionCount++;
unsigned ValueEnumerator::getValueID(const Value *V) const {
if (auto *MD = dyn_cast<MetadataAsValue>(V))
return getMetadataID(MD->getMetadata());
ValueMapType::const_iterator I = ValueMap.find(V);
assert(I != ValueMap.end() && "Value not in slotcalculator!");
return I->second-1;
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void ValueEnumerator::dump() const {
print(dbgs(), ValueMap, "Default");
dbgs() << '\n';
print(dbgs(), MetadataMap, "MetaData");
dbgs() << '\n';
void ValueEnumerator::print(raw_ostream &OS, const ValueMapType &Map,
const char *Name) const {
OS << "Map Name: " << Name << "\n";
OS << "Size: " << Map.size() << "\n";
for (ValueMapType::const_iterator I = Map.begin(),
E = Map.end(); I != E; ++I) {
const Value *V = I->first;
if (V->hasName())
OS << "Value: " << V->getName();
OS << "Value: [null]\n";
errs() << '\n';
OS << " Uses(" << V->getNumUses() << "):";
for (const Use &U : V->uses()) {
if (&U != &*V->use_begin())
OS << ",";
OS << " " << U->getName();
OS << " [null]";
OS << "\n\n";
void ValueEnumerator::print(raw_ostream &OS, const MetadataMapType &Map,
const char *Name) const {
OS << "Map Name: " << Name << "\n";
OS << "Size: " << Map.size() << "\n";
for (auto I = Map.begin(), E = Map.end(); I != E; ++I) {
const Metadata *MD = I->first;
OS << "Metadata: slot = " << I->second.ID << "\n";
OS << "Metadata: function = " << I->second.F << "\n";
OS << "\n";
/// OptimizeConstants - Reorder constant pool for denser encoding.
void ValueEnumerator::OptimizeConstants(unsigned CstStart, unsigned CstEnd) {
if (CstStart == CstEnd || CstStart+1 == CstEnd) return;
if (ShouldPreserveUseListOrder)
// Optimizing constants makes the use-list order difficult to predict.
// Disable it for now when trying to preserve the order.
std::stable_sort(Values.begin() + CstStart, Values.begin() + CstEnd,
[this](const std::pair<const Value *, unsigned> &LHS,
const std::pair<const Value *, unsigned> &RHS) {
// Sort by plane.
if (LHS.first->getType() != RHS.first->getType())
return getTypeID(LHS.first->getType()) < getTypeID(RHS.first->getType());
// Then by frequency.
return LHS.second > RHS.second;
// Ensure that integer and vector of integer constants are at the start of the
// constant pool. This is important so that GEP structure indices come before
// gep constant exprs.
std::stable_partition(Values.begin() + CstStart, Values.begin() + CstEnd,
// Rebuild the modified portion of ValueMap.
for (; CstStart != CstEnd; ++CstStart)
ValueMap[Values[CstStart].first] = CstStart+1;
/// EnumerateValueSymbolTable - Insert all of the values in the specified symbol
/// table into the values table.
void ValueEnumerator::EnumerateValueSymbolTable(const ValueSymbolTable &VST) {
for (ValueSymbolTable::const_iterator VI = VST.begin(), VE = VST.end();
VI != VE; ++VI)
/// Insert all of the values referenced by named metadata in the specified
/// module.
void ValueEnumerator::EnumerateNamedMetadata(const Module &M) {
for (const auto &I : M.named_metadata())
void ValueEnumerator::EnumerateNamedMDNode(const NamedMDNode *MD) {
for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i)
EnumerateMetadata(nullptr, MD->getOperand(i));
unsigned ValueEnumerator::getMetadataFunctionID(const Function *F) const {
return F ? getValueID(F) + 1 : 0;
void ValueEnumerator::EnumerateMetadata(const Function *F, const Metadata *MD) {
EnumerateMetadata(getMetadataFunctionID(F), MD);
void ValueEnumerator::EnumerateFunctionLocalMetadata(
const Function &F, const LocalAsMetadata *Local) {
EnumerateFunctionLocalMetadata(getMetadataFunctionID(&F), Local);
void ValueEnumerator::dropFunctionFromMetadata(
MetadataMapType::value_type &FirstMD) {
SmallVector<const MDNode *, 64> Worklist;
auto push = [&Worklist](MetadataMapType::value_type &MD) {
auto &Entry = MD.second;
// Nothing to do if this metadata isn't tagged.
if (!Entry.F)
// Drop the function tag.
Entry.F = 0;
// If this is has an ID and is an MDNode, then its operands have entries as
// well. We need to drop the function from them too.
if (Entry.ID)
if (auto *N = dyn_cast<MDNode>(MD.first))
while (!Worklist.empty())
for (const Metadata *Op : Worklist.pop_back_val()->operands()) {
if (!Op)
auto MD = MetadataMap.find(Op);
if (MD != MetadataMap.end())
void ValueEnumerator::EnumerateMetadata(unsigned F, const Metadata *MD) {
// It's vital for reader efficiency that uniqued subgraphs are done in
// post-order; it's expensive when their operands have forward references.
// If a distinct node is referenced from a uniqued node, it'll be delayed
// until the uniqued subgraph has been completely traversed.
SmallVector<const MDNode *, 32> DelayedDistinctNodes;
// Start by enumerating MD, and then work through its transitive operands in
// post-order. This requires a depth-first search.
SmallVector<std::pair<const MDNode *, MDNode::op_iterator>, 32> Worklist;
if (const MDNode *N = enumerateMetadataImpl(F, MD))
Worklist.push_back(std::make_pair(N, N->op_begin()));
while (!Worklist.empty()) {
const MDNode *N = Worklist.back().first;
// Enumerate operands until we hit a new node. We need to traverse these
// nodes' operands before visiting the rest of N's operands.
MDNode::op_iterator I = std::find_if(
Worklist.back().second, N->op_end(),
[&](const Metadata *MD) { return enumerateMetadataImpl(F, MD); });
if (I != N->op_end()) {
auto *Op = cast<MDNode>(*I);
Worklist.back().second = ++I;
// Delay traversing Op if it's a distinct node and N is uniqued.
if (Op->isDistinct() && !N->isDistinct())
Worklist.push_back(std::make_pair(Op, Op->op_begin()));
// All the operands have been visited. Now assign an ID.
MetadataMap[N].ID = MDs.size();
// Flush out any delayed distinct nodes; these are all the distinct nodes
// that are leaves in last uniqued subgraph.
if (Worklist.empty() || Worklist.back().first->isDistinct()) {
for (const MDNode *N : DelayedDistinctNodes)
Worklist.push_back(std::make_pair(N, N->op_begin()));
const MDNode *ValueEnumerator::enumerateMetadataImpl(unsigned F, const Metadata *MD) {
if (!MD)
return nullptr;
(isa<MDNode>(MD) || isa<MDString>(MD) || isa<ConstantAsMetadata>(MD)) &&
"Invalid metadata kind");
auto Insertion = MetadataMap.insert(std::make_pair(MD, MDIndex(F)));
MDIndex &Entry = Insertion.first->second;
if (!Insertion.second) {
// Already mapped. If F doesn't match the function tag, drop it.
if (Entry.hasDifferentFunction(F))
return nullptr;
// Don't assign IDs to metadata nodes.
if (auto *N = dyn_cast<MDNode>(MD))
return N;
// Save the metadata.
Entry.ID = MDs.size();
// Enumerate the constant, if any.
if (auto *C = dyn_cast<ConstantAsMetadata>(MD))
return nullptr;
/// EnumerateFunctionLocalMetadataa - Incorporate function-local metadata
/// information reachable from the metadata.
void ValueEnumerator::EnumerateFunctionLocalMetadata(
unsigned F, const LocalAsMetadata *Local) {
assert(F && "Expected a function");
// Check to see if it's already in!
MDIndex &Index = MetadataMap[Local];
if (Index.ID) {
assert(Index.F == F && "Expected the same function");
Index.F = F;
Index.ID = MDs.size();
static unsigned getMetadataTypeOrder(const Metadata *MD) {
// Strings are emitted in bulk and must come first.
if (isa<MDString>(MD))
return 0;
// ConstantAsMetadata doesn't reference anything. We may as well shuffle it
// to the front since we can detect it.
auto *N = dyn_cast<MDNode>(MD);
if (!N)
return 1;
// The reader is fast forward references for distinct node operands, but slow
// when uniqued operands are unresolved.
return N->isDistinct() ? 2 : 3;
void ValueEnumerator::organizeMetadata() {
assert(MetadataMap.size() == MDs.size() &&
"Metadata map and vector out of sync");
if (MDs.empty())
// Copy out the index information from MetadataMap in order to choose a new
// order.
SmallVector<MDIndex, 64> Order;
for (const Metadata *MD : MDs)
// Partition:
// - by function, then
// - by isa<MDString>
// and then sort by the original/current ID. Since the IDs are guaranteed to
// be unique, the result of std::sort will be deterministic. There's no need
// for std::stable_sort.
llvm::sort(Order, [this](MDIndex LHS, MDIndex RHS) {
return std::make_tuple(LHS.F, getMetadataTypeOrder(LHS.get(MDs)), LHS.ID) <
std::make_tuple(RHS.F, getMetadataTypeOrder(RHS.get(MDs)), RHS.ID);
// Rebuild MDs, index the metadata ranges for each function in FunctionMDs,
// and fix up MetadataMap.
std::vector<const Metadata *> OldMDs;
for (unsigned I = 0, E = Order.size(); I != E && !Order[I].F; ++I) {
auto *MD = Order[I].get(OldMDs);
MetadataMap[MD].ID = I + 1;
if (isa<MDString>(MD))
// Return early if there's nothing for the functions.
if (MDs.size() == Order.size())
// Build the function metadata ranges.
MDRange R;
unsigned PrevF = 0;
for (unsigned I = MDs.size(), E = Order.size(), ID = MDs.size(); I != E;
++I) {
unsigned F = Order[I].F;
if (!PrevF) {
PrevF = F;
} else if (PrevF != F) {
R.Last = FunctionMDs.size();
std::swap(R, FunctionMDInfo[PrevF]);
R.First = FunctionMDs.size();
ID = MDs.size();
PrevF = F;
auto *MD = Order[I].get(OldMDs);
MetadataMap[MD].ID = ++ID;
if (isa<MDString>(MD))
R.Last = FunctionMDs.size();
FunctionMDInfo[PrevF] = R;
void ValueEnumerator::incorporateFunctionMetadata(const Function &F) {
NumModuleMDs = MDs.size();
auto R = FunctionMDInfo.lookup(getValueID(&F) + 1);
NumMDStrings = R.NumStrings;
MDs.insert(MDs.end(), FunctionMDs.begin() + R.First,
FunctionMDs.begin() + R.Last);
void ValueEnumerator::EnumerateValue(const Value *V) {
assert(!V->getType()->isVoidTy() && "Can't insert void values!");
assert(!isa<MetadataAsValue>(V) && "EnumerateValue doesn't handle Metadata!");
// Check to see if it's already in!
unsigned &ValueID = ValueMap[V];
if (ValueID) {
// Increment use count.
if (auto *GO = dyn_cast<GlobalObject>(V))
if (const Comdat *C = GO->getComdat())
// Enumerate the type of this value.
if (const Constant *C = dyn_cast<Constant>(V)) {
if (isa<GlobalValue>(C)) {
// Initializers for globals are handled explicitly elsewhere.
} else if (C->getNumOperands()) {
// If a constant has operands, enumerate them. This makes sure that if a
// constant has uses (for example an array of const ints), that they are
// inserted also.
// We prefer to enumerate them with values before we enumerate the user
// itself. This makes it more likely that we can avoid forward references
// in the reader. We know that there can be no cycles in the constants
// graph that don't go through a global variable.
for (User::const_op_iterator I = C->op_begin(), E = C->op_end();
I != E; ++I)
if (!isa<BasicBlock>(*I)) // Don't enumerate BB operand to BlockAddress.
if (auto *CE = dyn_cast<ConstantExpr>(C))
if (CE->getOpcode() == Instruction::ShuffleVector)
// Finally, add the value. Doing this could make the ValueID reference be
// dangling, don't reuse it.
Values.push_back(std::make_pair(V, 1U));
ValueMap[V] = Values.size();
// Add the value.
Values.push_back(std::make_pair(V, 1U));
ValueID = Values.size();
void ValueEnumerator::EnumerateType(Type *Ty) {
unsigned *TypeID = &TypeMap[Ty];
// We've already seen this type.
if (*TypeID)
// If it is a non-anonymous struct, mark the type as being visited so that we
// don't recursively visit it. This is safe because we allow forward
// references of these in the bitcode reader.
if (StructType *STy = dyn_cast<StructType>(Ty))
if (!STy->isLiteral())
*TypeID = ~0U;
// Enumerate all of the subtypes before we enumerate this type. This ensures
// that the type will be enumerated in an order that can be directly built.
for (Type *SubTy : Ty->subtypes())
// Refresh the TypeID pointer in case the table rehashed.
TypeID = &TypeMap[Ty];
// Check to see if we got the pointer another way. This can happen when
// enumerating recursive types that hit the base case deeper than they start.
// If this is actually a struct that we are treating as forward ref'able,
// then emit the definition now that all of its contents are available.
if (*TypeID && *TypeID != ~0U)
// Add this type now that its contents are all happily enumerated.
*TypeID = Types.size();
// Enumerate the types for the specified value. If the value is a constant,
// walk through it, enumerating the types of the constant.
void ValueEnumerator::EnumerateOperandType(const Value *V) {
assert(!isa<MetadataAsValue>(V) && "Unexpected metadata operand");
const Constant *C = dyn_cast<Constant>(V);
if (!C)
// If this constant is already enumerated, ignore it, we know its type must
// be enumerated.
if (ValueMap.count(C))
// This constant may have operands, make sure to enumerate the types in
// them.
for (const Value *Op : C->operands()) {
// Don't enumerate basic blocks here, this happens as operands to
// blockaddress.
if (isa<BasicBlock>(Op))
if (auto *CE = dyn_cast<ConstantExpr>(C))
if (CE->getOpcode() == Instruction::ShuffleVector)
void ValueEnumerator::EnumerateAttributes(AttributeList PAL) {
if (PAL.isEmpty()) return; // null is always 0.
// Do a lookup.
unsigned &Entry = AttributeListMap[PAL];
if (Entry == 0) {
// Never saw this before, add it.
Entry = AttributeLists.size();
// Do lookups for all attribute groups.
for (unsigned i = PAL.index_begin(), e = PAL.index_end(); i != e; ++i) {
AttributeSet AS = PAL.getAttributes(i);
if (!AS.hasAttributes())
IndexAndAttrSet Pair = {i, AS};
unsigned &Entry = AttributeGroupMap[Pair];
if (Entry == 0) {
Entry = AttributeGroups.size();
void ValueEnumerator::incorporateFunction(const Function &F) {
InstructionCount = 0;
NumModuleValues = Values.size();
// Add global metadata to the function block. This doesn't include
// LocalAsMetadata.
// Adding function arguments to the value table.
for (const auto &I : F.args()) {
if (I.hasAttribute(Attribute::ByVal))
else if (I.hasAttribute(Attribute::StructRet))
else if (I.hasAttribute(Attribute::ByRef))
FirstFuncConstantID = Values.size();
// Add all function-level constants to the value table.
for (const BasicBlock &BB : F) {
for (const Instruction &I : BB) {
for (const Use &OI : I.operands()) {
if ((isa<Constant>(OI) && !isa<GlobalValue>(OI)) || isa<InlineAsm>(OI))
if (auto *SVI = dyn_cast<ShuffleVectorInst>(&I))
ValueMap[&BB] = BasicBlocks.size();
// Optimize the constant layout.
OptimizeConstants(FirstFuncConstantID, Values.size());
// Add the function's parameter attributes so they are available for use in
// the function's instruction.
FirstInstID = Values.size();
SmallVector<LocalAsMetadata *, 8> FnLocalMDVector;
SmallVector<DIArgList *, 8> ArgListMDVector;
// Add all of the instructions.
for (const BasicBlock &BB : F) {
for (const Instruction &I : BB) {
for (const Use &OI : I.operands()) {
if (auto *MD = dyn_cast<MetadataAsValue>(&OI)) {
if (auto *Local = dyn_cast<LocalAsMetadata>(MD->getMetadata())) {
// Enumerate metadata after the instructions they might refer to.
} else if (auto *ArgList = dyn_cast<DIArgList>(MD->getMetadata())) {
for (ValueAsMetadata *VMD : ArgList->getArgs()) {
if (auto *Local = dyn_cast<LocalAsMetadata>(VMD)) {
// Enumerate metadata after the instructions they might refer
// to.
if (!I.getType()->isVoidTy())
// Add all of the function-local metadata.
for (unsigned i = 0, e = FnLocalMDVector.size(); i != e; ++i) {
// At this point, every local values have been incorporated, we shouldn't
// have a metadata operand that references a value that hasn't been seen.
assert(ValueMap.count(FnLocalMDVector[i]->getValue()) &&
"Missing value for metadata operand");
EnumerateFunctionLocalMetadata(F, FnLocalMDVector[i]);
// DIArgList entries must come after function-local metadata, as it is not
// possible to forward-reference them.
for (const DIArgList *ArgList : ArgListMDVector)
EnumerateMetadata(&F, ArgList);
void ValueEnumerator::purgeFunction() {
/// Remove purged values from the ValueMap.
for (unsigned i = NumModuleValues, e = Values.size(); i != e; ++i)
for (unsigned i = NumModuleMDs, e = MDs.size(); i != e; ++i)
for (unsigned i = 0, e = BasicBlocks.size(); i != e; ++i)
NumMDStrings = 0;
static void IncorporateFunctionInfoGlobalBBIDs(const Function *F,
DenseMap<const BasicBlock*, unsigned> &IDMap) {
unsigned Counter = 0;
for (const BasicBlock &BB : *F)
IDMap[&BB] = ++Counter;
/// getGlobalBasicBlockID - This returns the function-specific ID for the
/// specified basic block. This is relatively expensive information, so it
/// should only be used by rare constructs such as address-of-label.
unsigned ValueEnumerator::getGlobalBasicBlockID(const BasicBlock *BB) const {
unsigned &Idx = GlobalBasicBlockIDs[BB];
if (Idx != 0)
return Idx-1;
IncorporateFunctionInfoGlobalBBIDs(BB->getParent(), GlobalBasicBlockIDs);
return getGlobalBasicBlockID(BB);
uint64_t ValueEnumerator::computeBitsRequiredForTypeIndicies() const {
return Log2_32_Ceil(getTypes().size() + 1);