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llvm-project/llvm/lib/Linker/LinkModules.cpp

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//===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
//
// 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 LLVM module linker.
//
//===----------------------------------------------------------------------===//
#include "llvm/Linker/Linker.h"
#include "LinkDiagnosticInfo.h"
#include "llvm-c/Linker.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/LLVMContext.h"
using namespace llvm;
namespace {
/// This is an implementation class for the LinkModules function, which is the
/// entrypoint for this file.
class ModuleLinker {
IRMover &Mover;
Module &SrcM;
SetVector<GlobalValue *> ValuesToLink;
StringSet<> Internalize;
/// For symbol clashes, prefer those from Src.
unsigned Flags;
/// Function index passed into ModuleLinker for using in function
/// importing/exporting handling.
const FunctionInfoIndex *ImportIndex;
/// Functions to import from source module, all other functions are
/// imported as declarations instead of definitions.
DenseSet<const GlobalValue *> *FunctionsToImport;
/// Set to true if the given FunctionInfoIndex contains any functions
/// from this source module, in which case we must conservatively assume
/// that any of its functions may be imported into another module
/// as part of a different backend compilation process.
bool HasExportedFunctions = false;
/// Association between metadata value id and temporary metadata that
/// remains unmapped after function importing. Saved during function
/// importing and consumed during the metadata linking postpass.
DenseMap<unsigned, MDNode *> *ValIDToTempMDMap;
/// Used as the callback for lazy linking.
/// The mover has just hit GV and we have to decide if it, and other members
/// of the same comdat, should be linked. Every member to be linked is passed
/// to Add.
void addLazyFor(GlobalValue &GV, IRMover::ValueAdder Add);
bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
bool shouldInternalizeLinkedSymbols() {
return Flags & Linker::InternalizeLinkedSymbols;
}
/// Check if we should promote the given local value to global scope.
bool doPromoteLocalToGlobal(const GlobalValue *SGV);
bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
const GlobalValue &Src);
/// Should we have mover and linker error diag info?
bool emitError(const Twine &Message) {
SrcM.getContext().diagnose(LinkDiagnosticInfo(DS_Error, Message));
return true;
}
bool getComdatLeader(Module &M, StringRef ComdatName,
const GlobalVariable *&GVar);
bool computeResultingSelectionKind(StringRef ComdatName,
Comdat::SelectionKind Src,
Comdat::SelectionKind Dst,
Comdat::SelectionKind &Result,
bool &LinkFromSrc);
std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
ComdatsChosen;
bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
bool &LinkFromSrc);
// Keep track of the global value members of each comdat in source.
DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
/// Given a global in the source module, return the global in the
/// destination module that is being linked to, if any.
GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
Module &DstM = Mover.getModule();
// If the source has no name it can't link. If it has local linkage,
// there is no name match-up going on.
if (!SrcGV->hasName() || GlobalValue::isLocalLinkage(getLinkage(SrcGV)))
return nullptr;
// Otherwise see if we have a match in the destination module's symtab.
GlobalValue *DGV = DstM.getNamedValue(getName(SrcGV));
if (!DGV)
return nullptr;
// If we found a global with the same name in the dest module, but it has
// internal linkage, we are really not doing any linkage here.
if (DGV->hasLocalLinkage())
return nullptr;
// Otherwise, we do in fact link to the destination global.
return DGV;
}
bool linkIfNeeded(GlobalValue &GV);
/// Helper methods to check if we are importing from or potentially
/// exporting from the current source module.
bool isPerformingImport() const { return FunctionsToImport != nullptr; }
bool isModuleExporting() const { return HasExportedFunctions; }
/// If we are importing from the source module, checks if we should
/// import SGV as a definition, otherwise import as a declaration.
bool doImportAsDefinition(const GlobalValue *SGV);
/// Get the name for SGV that should be used in the linked destination
/// module. Specifically, this handles the case where we need to rename
/// a local that is being promoted to global scope.
std::string getName(const GlobalValue *SGV);
/// Process globals so that they can be used in ThinLTO. This includes
/// promoting local variables so that they can be reference externally by
/// thin lto imported globals and converting strong external globals to
/// available_externally.
void processGlobalsForThinLTO();
void processGlobalForThinLTO(GlobalValue &GV);
/// Get the new linkage for SGV that should be used in the linked destination
/// module. Specifically, for ThinLTO importing or exporting it may need
/// to be adjusted.
GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
public:
ModuleLinker(IRMover &Mover, Module &SrcM, unsigned Flags,
const FunctionInfoIndex *Index = nullptr,
DenseSet<const GlobalValue *> *FunctionsToImport = nullptr,
DenseMap<unsigned, MDNode *> *ValIDToTempMDMap = nullptr)
: Mover(Mover), SrcM(SrcM), Flags(Flags), ImportIndex(Index),
FunctionsToImport(FunctionsToImport),
ValIDToTempMDMap(ValIDToTempMDMap) {
assert((ImportIndex || !FunctionsToImport) &&
"Expect a FunctionInfoIndex when importing");
// If we have a FunctionInfoIndex but no function to import,
// then this is the primary module being compiled in a ThinLTO
// backend compilation, and we need to see if it has functions that
// may be exported to another backend compilation.
if (ImportIndex && !FunctionsToImport)
HasExportedFunctions = ImportIndex->hasExportedFunctions(SrcM);
assert((ValIDToTempMDMap || !FunctionsToImport) &&
"Function importing must provide a ValIDToTempMDMap");
}
bool run();
};
}
bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
if (!isPerformingImport())
return false;
auto *GA = dyn_cast<GlobalAlias>(SGV);
if (GA) {
if (GA->hasWeakAnyLinkage())
return false;
const GlobalObject *GO = GA->getBaseObject();
if (!GO->hasLinkOnceODRLinkage())
return false;
return doImportAsDefinition(GO);
}
// Always import GlobalVariable definitions, except for the special
// case of WeakAny which are imported as ExternalWeak declarations
// (see comments in ModuleLinker::getLinkage). The linkage changes
// described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
// global variables with external linkage are transformed to
// available_externally definitions, which are ultimately turned into
// declarations after the EliminateAvailableExternally pass).
if (isa<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
!SGV->hasWeakAnyLinkage())
return true;
// Only import the function requested for importing.
auto *SF = dyn_cast<Function>(SGV);
if (SF && FunctionsToImport->count(SF))
return true;
// Otherwise no.
return false;
}
bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
assert(SGV->hasLocalLinkage());
// Both the imported references and the original local variable must
// be promoted.
if (!isPerformingImport() && !isModuleExporting())
return false;
// Local const variables never need to be promoted unless they are address
// taken. The imported uses can simply use the clone created in this module.
// For now we are conservative in determining which variables are not
// address taken by checking the unnamed addr flag. To be more aggressive,
// the address taken information must be checked earlier during parsing
// of the module and recorded in the function index for use when importing
// from that module.
auto *GVar = dyn_cast<GlobalVariable>(SGV);
if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
return false;
// Eventually we only need to promote functions in the exporting module that
// are referenced by a potentially exported function (i.e. one that is in the
// function index).
return true;
}
std::string ModuleLinker::getName(const GlobalValue *SGV) {
// For locals that must be promoted to global scope, ensure that
// the promoted name uniquely identifies the copy in the original module,
// using the ID assigned during combined index creation. When importing,
// we rename all locals (not just those that are promoted) in order to
// avoid naming conflicts between locals imported from different modules.
if (SGV->hasLocalLinkage() &&
(doPromoteLocalToGlobal(SGV) || isPerformingImport()))
return FunctionInfoIndex::getGlobalNameForLocal(
SGV->getName(),
ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
return SGV->getName();
}
GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
// Any local variable that is referenced by an exported function needs
// to be promoted to global scope. Since we don't currently know which
// functions reference which local variables/functions, we must treat
// all as potentially exported if this module is exporting anything.
if (isModuleExporting()) {
if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
return GlobalValue::ExternalLinkage;
return SGV->getLinkage();
}
// Otherwise, if we aren't importing, no linkage change is needed.
if (!isPerformingImport())
return SGV->getLinkage();
switch (SGV->getLinkage()) {
case GlobalValue::ExternalLinkage:
// External defnitions are converted to available_externally
// definitions upon import, so that they are available for inlining
// and/or optimization, but are turned into declarations later
// during the EliminateAvailableExternally pass.
if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
return GlobalValue::AvailableExternallyLinkage;
// An imported external declaration stays external.
return SGV->getLinkage();
case GlobalValue::AvailableExternallyLinkage:
// An imported available_externally definition converts
// to external if imported as a declaration.
if (!doImportAsDefinition(SGV))
return GlobalValue::ExternalLinkage;
// An imported available_externally declaration stays that way.
return SGV->getLinkage();
case GlobalValue::LinkOnceAnyLinkage:
case GlobalValue::LinkOnceODRLinkage:
// These both stay the same when importing the definition.
// The ThinLTO pass will eventually force-import their definitions.
return SGV->getLinkage();
case GlobalValue::WeakAnyLinkage:
// Can't import weak_any definitions correctly, or we might change the
// program semantics, since the linker will pick the first weak_any
// definition and importing would change the order they are seen by the
// linker. The module linking caller needs to enforce this.
assert(!doImportAsDefinition(SGV));
// If imported as a declaration, it becomes external_weak.
return GlobalValue::ExternalWeakLinkage;
case GlobalValue::WeakODRLinkage:
// For weak_odr linkage, there is a guarantee that all copies will be
// equivalent, so the issue described above for weak_any does not exist,
// and the definition can be imported. It can be treated similarly
// to an imported externally visible global value.
if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
return GlobalValue::AvailableExternallyLinkage;
else
return GlobalValue::ExternalLinkage;
case GlobalValue::AppendingLinkage:
// It would be incorrect to import an appending linkage variable,
// since it would cause global constructors/destructors to be
// executed multiple times. This should have already been handled
// by linkIfNeeded, and we will assert in shouldLinkFromSource
// if we try to import, so we simply return AppendingLinkage here
// as this helper is called more widely in getLinkedToGlobal.
return GlobalValue::AppendingLinkage;
case GlobalValue::InternalLinkage:
case GlobalValue::PrivateLinkage:
// If we are promoting the local to global scope, it is handled
// similarly to a normal externally visible global.
if (doPromoteLocalToGlobal(SGV)) {
if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
return GlobalValue::AvailableExternallyLinkage;
else
return GlobalValue::ExternalLinkage;
}
// A non-promoted imported local definition stays local.
// The ThinLTO pass will eventually force-import their definitions.
return SGV->getLinkage();
case GlobalValue::ExternalWeakLinkage:
// External weak doesn't apply to definitions, must be a declaration.
assert(!doImportAsDefinition(SGV));
// Linkage stays external_weak.
return SGV->getLinkage();
case GlobalValue::CommonLinkage:
// Linkage stays common on definitions.
// The ThinLTO pass will eventually force-import their definitions.
return SGV->getLinkage();
}
llvm_unreachable("unknown linkage type");
}
static GlobalValue::VisibilityTypes
getMinVisibility(GlobalValue::VisibilityTypes A,
GlobalValue::VisibilityTypes B) {
if (A == GlobalValue::HiddenVisibility || B == GlobalValue::HiddenVisibility)
return GlobalValue::HiddenVisibility;
if (A == GlobalValue::ProtectedVisibility ||
B == GlobalValue::ProtectedVisibility)
return GlobalValue::ProtectedVisibility;
return GlobalValue::DefaultVisibility;
}
bool ModuleLinker::getComdatLeader(Module &M, StringRef ComdatName,
const GlobalVariable *&GVar) {
const GlobalValue *GVal = M.getNamedValue(ComdatName);
if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
GVal = GA->getBaseObject();
if (!GVal)
// We cannot resolve the size of the aliasee yet.
return emitError("Linking COMDATs named '" + ComdatName +
"': COMDAT key involves incomputable alias size.");
}
GVar = dyn_cast_or_null<GlobalVariable>(GVal);
if (!GVar)
return emitError(
"Linking COMDATs named '" + ComdatName +
"': GlobalVariable required for data dependent selection!");
return false;
}
bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
Comdat::SelectionKind Src,
Comdat::SelectionKind Dst,
Comdat::SelectionKind &Result,
bool &LinkFromSrc) {
Module &DstM = Mover.getModule();
// The ability to mix Comdat::SelectionKind::Any with
// Comdat::SelectionKind::Largest is a behavior that comes from COFF.
bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
Dst == Comdat::SelectionKind::Largest;
bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
Src == Comdat::SelectionKind::Largest;
if (DstAnyOrLargest && SrcAnyOrLargest) {
if (Dst == Comdat::SelectionKind::Largest ||
Src == Comdat::SelectionKind::Largest)
Result = Comdat::SelectionKind::Largest;
else
Result = Comdat::SelectionKind::Any;
} else if (Src == Dst) {
Result = Dst;
} else {
return emitError("Linking COMDATs named '" + ComdatName +
"': invalid selection kinds!");
}
switch (Result) {
case Comdat::SelectionKind::Any:
// Go with Dst.
LinkFromSrc = false;
break;
case Comdat::SelectionKind::NoDuplicates:
return emitError("Linking COMDATs named '" + ComdatName +
"': noduplicates has been violated!");
case Comdat::SelectionKind::ExactMatch:
case Comdat::SelectionKind::Largest:
case Comdat::SelectionKind::SameSize: {
const GlobalVariable *DstGV;
const GlobalVariable *SrcGV;
if (getComdatLeader(DstM, ComdatName, DstGV) ||
getComdatLeader(SrcM, ComdatName, SrcGV))
return true;
const DataLayout &DstDL = DstM.getDataLayout();
const DataLayout &SrcDL = SrcM.getDataLayout();
uint64_t DstSize =
DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
uint64_t SrcSize =
SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
if (Result == Comdat::SelectionKind::ExactMatch) {
if (SrcGV->getInitializer() != DstGV->getInitializer())
return emitError("Linking COMDATs named '" + ComdatName +
"': ExactMatch violated!");
LinkFromSrc = false;
} else if (Result == Comdat::SelectionKind::Largest) {
LinkFromSrc = SrcSize > DstSize;
} else if (Result == Comdat::SelectionKind::SameSize) {
if (SrcSize != DstSize)
return emitError("Linking COMDATs named '" + ComdatName +
"': SameSize violated!");
LinkFromSrc = false;
} else {
llvm_unreachable("unknown selection kind");
}
break;
}
}
return false;
}
bool ModuleLinker::getComdatResult(const Comdat *SrcC,
Comdat::SelectionKind &Result,
bool &LinkFromSrc) {
Module &DstM = Mover.getModule();
Comdat::SelectionKind SSK = SrcC->getSelectionKind();
StringRef ComdatName = SrcC->getName();
Module::ComdatSymTabType &ComdatSymTab = DstM.getComdatSymbolTable();
Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
if (DstCI == ComdatSymTab.end()) {
// Use the comdat if it is only available in one of the modules.
LinkFromSrc = true;
Result = SSK;
return false;
}
const Comdat *DstC = &DstCI->second;
Comdat::SelectionKind DSK = DstC->getSelectionKind();
return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
LinkFromSrc);
}
bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
const GlobalValue &Dest,
const GlobalValue &Src) {
// Should we unconditionally use the Src?
if (shouldOverrideFromSrc()) {
LinkFromSrc = true;
return false;
}
// We always have to add Src if it has appending linkage.
if (Src.hasAppendingLinkage()) {
// Should have prevented importing for appending linkage in linkIfNeeded.
assert(!isPerformingImport());
LinkFromSrc = true;
return false;
}
bool SrcIsDeclaration = Src.isDeclarationForLinker();
bool DestIsDeclaration = Dest.isDeclarationForLinker();
if (isPerformingImport()) {
if (isa<Function>(&Src)) {
// For functions, LinkFromSrc iff this is a function requested
// for importing. For variables, decide below normally.
LinkFromSrc = FunctionsToImport->count(&Src);
return false;
}
// Check if this is an alias with an already existing definition
// in Dest, which must have come from a prior importing pass from
// the same Src module. Unlike imported function and variable
// definitions, which are imported as available_externally and are
// not definitions for the linker, that is not a valid linkage for
// imported aliases which must be definitions. Simply use the existing
// Dest copy.
if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
assert(isa<GlobalAlias>(&Dest));
LinkFromSrc = false;
return false;
}
}
if (SrcIsDeclaration) {
// If Src is external or if both Src & Dest are external.. Just link the
// external globals, we aren't adding anything.
if (Src.hasDLLImportStorageClass()) {
// If one of GVs is marked as DLLImport, result should be dllimport'ed.
LinkFromSrc = DestIsDeclaration;
return false;
}
// If the Dest is weak, use the source linkage.
if (Dest.hasExternalWeakLinkage()) {
LinkFromSrc = true;
return false;
}
// Link an available_externally over a declaration.
LinkFromSrc = !Src.isDeclaration() && Dest.isDeclaration();
return false;
}
if (DestIsDeclaration) {
// If Dest is external but Src is not:
LinkFromSrc = true;
return false;
}
if (Src.hasCommonLinkage()) {
if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
LinkFromSrc = true;
return false;
}
if (!Dest.hasCommonLinkage()) {
LinkFromSrc = false;
return false;
}
const DataLayout &DL = Dest.getParent()->getDataLayout();
uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
LinkFromSrc = SrcSize > DestSize;
return false;
}
if (Src.isWeakForLinker()) {
assert(!Dest.hasExternalWeakLinkage());
assert(!Dest.hasAvailableExternallyLinkage());
if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
LinkFromSrc = true;
return false;
}
LinkFromSrc = false;
return false;
}
if (Dest.isWeakForLinker()) {
assert(Src.hasExternalLinkage());
LinkFromSrc = true;
return false;
}
assert(!Src.hasExternalWeakLinkage());
assert(!Dest.hasExternalWeakLinkage());
assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
"Unexpected linkage type!");
return emitError("Linking globals named '" + Src.getName() +
"': symbol multiply defined!");
}
bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
GlobalValue *DGV = getLinkedToGlobal(&GV);
if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration()))
return false;
if (DGV && !GV.hasLocalLinkage() && !GV.hasAppendingLinkage()) {
auto *DGVar = dyn_cast<GlobalVariable>(DGV);
auto *SGVar = dyn_cast<GlobalVariable>(&GV);
if (DGVar && SGVar) {
if (DGVar->isDeclaration() && SGVar->isDeclaration() &&
(!DGVar->isConstant() || !SGVar->isConstant())) {
DGVar->setConstant(false);
SGVar->setConstant(false);
}
if (DGVar->hasCommonLinkage() && SGVar->hasCommonLinkage()) {
unsigned Align = std::max(DGVar->getAlignment(), SGVar->getAlignment());
SGVar->setAlignment(Align);
DGVar->setAlignment(Align);
}
}
GlobalValue::VisibilityTypes Visibility =
getMinVisibility(DGV->getVisibility(), GV.getVisibility());
DGV->setVisibility(Visibility);
GV.setVisibility(Visibility);
bool HasUnnamedAddr = GV.hasUnnamedAddr() && DGV->hasUnnamedAddr();
DGV->setUnnamedAddr(HasUnnamedAddr);
GV.setUnnamedAddr(HasUnnamedAddr);
}
// Don't want to append to global_ctors list, for example, when we
// are importing for ThinLTO, otherwise the global ctors and dtors
// get executed multiple times for local variables (the latter causing
// double frees).
if (GV.hasAppendingLinkage() && isPerformingImport())
return false;
if (isPerformingImport() && !doImportAsDefinition(&GV))
return false;
if (!DGV && !shouldOverrideFromSrc() &&
(GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
GV.hasAvailableExternallyLinkage()))
return false;
if (GV.isDeclaration())
return false;
if (const Comdat *SC = GV.getComdat()) {
bool LinkFromSrc;
Comdat::SelectionKind SK;
std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
if (LinkFromSrc)
ValuesToLink.insert(&GV);
return false;
}
bool LinkFromSrc = true;
if (DGV && shouldLinkFromSource(LinkFromSrc, *DGV, GV))
return true;
if (LinkFromSrc)
ValuesToLink.insert(&GV);
return false;
}
void ModuleLinker::addLazyFor(GlobalValue &GV, IRMover::ValueAdder Add) {
// Add these to the internalize list
if (!GV.hasLinkOnceLinkage())
return;
if (shouldInternalizeLinkedSymbols())
Internalize.insert(GV.getName());
Add(GV);
const Comdat *SC = GV.getComdat();
if (!SC)
return;
for (GlobalValue *GV2 : ComdatMembers[SC]) {
if (!GV2->hasLocalLinkage() && shouldInternalizeLinkedSymbols())
Internalize.insert(GV2->getName());
Add(*GV2);
}
}
void ModuleLinker::processGlobalForThinLTO(GlobalValue &GV) {
if (GV.hasLocalLinkage() &&
(doPromoteLocalToGlobal(&GV) || isPerformingImport())) {
GV.setName(getName(&GV));
GV.setLinkage(getLinkage(&GV));
if (!GV.hasLocalLinkage())
GV.setVisibility(GlobalValue::HiddenVisibility);
if (isModuleExporting())
ValuesToLink.insert(&GV);
return;
}
GV.setLinkage(getLinkage(&GV));
}
void ModuleLinker::processGlobalsForThinLTO() {
for (GlobalVariable &GV : SrcM.globals())
processGlobalForThinLTO(GV);
for (Function &SF : SrcM)
processGlobalForThinLTO(SF);
for (GlobalAlias &GA : SrcM.aliases())
processGlobalForThinLTO(GA);
}
bool ModuleLinker::run() {
for (const auto &SMEC : SrcM.getComdatSymbolTable()) {
const Comdat &C = SMEC.getValue();
if (ComdatsChosen.count(&C))
continue;
Comdat::SelectionKind SK;
bool LinkFromSrc;
if (getComdatResult(&C, SK, LinkFromSrc))
return true;
ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
}
for (GlobalVariable &GV : SrcM.globals())
if (const Comdat *SC = GV.getComdat())
ComdatMembers[SC].push_back(&GV);
for (Function &SF : SrcM)
if (const Comdat *SC = SF.getComdat())
ComdatMembers[SC].push_back(&SF);
for (GlobalAlias &GA : SrcM.aliases())
if (const Comdat *SC = GA.getComdat())
ComdatMembers[SC].push_back(&GA);
// Insert all of the globals in src into the DstM module... without linking
// initializers (which could refer to functions not yet mapped over).
for (GlobalVariable &GV : SrcM.globals())
if (linkIfNeeded(GV))
return true;
for (Function &SF : SrcM)
if (linkIfNeeded(SF))
return true;
for (GlobalAlias &GA : SrcM.aliases())
if (linkIfNeeded(GA))
return true;
processGlobalsForThinLTO();
for (unsigned I = 0; I < ValuesToLink.size(); ++I) {
GlobalValue *GV = ValuesToLink[I];
const Comdat *SC = GV->getComdat();
if (!SC)
continue;
for (GlobalValue *GV2 : ComdatMembers[SC])
ValuesToLink.insert(GV2);
}
if (shouldInternalizeLinkedSymbols()) {
for (GlobalValue *GV : ValuesToLink)
Internalize.insert(GV->getName());
}
if (Mover.move(SrcM, ValuesToLink.getArrayRef(),
[this](GlobalValue &GV, IRMover::ValueAdder Add) {
addLazyFor(GV, Add);
},
ValIDToTempMDMap, false))
return true;
Module &DstM = Mover.getModule();
for (auto &P : Internalize) {
GlobalValue *GV = DstM.getNamedValue(P.first());
GV->setLinkage(GlobalValue::InternalLinkage);
}
return false;
}
Linker::Linker(Module &M) : Mover(M) {}
bool Linker::linkInModule(std::unique_ptr<Module> Src, unsigned Flags,
const FunctionInfoIndex *Index,
DenseSet<const GlobalValue *> *FunctionsToImport,
DenseMap<unsigned, MDNode *> *ValIDToTempMDMap) {
ModuleLinker ModLinker(Mover, *Src, Flags, Index, FunctionsToImport,
ValIDToTempMDMap);
return ModLinker.run();
}
bool Linker::linkInModuleForCAPI(Module &Src) {
ModuleLinker ModLinker(Mover, Src, 0, nullptr, nullptr);
return ModLinker.run();
}
bool Linker::linkInMetadata(Module &Src,
DenseMap<unsigned, MDNode *> *ValIDToTempMDMap) {
SetVector<GlobalValue *> ValuesToLink;
if (Mover.move(
Src, ValuesToLink.getArrayRef(),
[this](GlobalValue &GV, IRMover::ValueAdder Add) { assert(false); },
ValIDToTempMDMap, true))
return true;
return false;
}
//===----------------------------------------------------------------------===//
// LinkModules entrypoint.
//===----------------------------------------------------------------------===//
/// This function links two modules together, with the resulting Dest module
/// modified to be the composite of the two input modules. If an error occurs,
/// true is returned and ErrorMsg (if not null) is set to indicate the problem.
/// Upon failure, the Dest module could be in a modified state, and shouldn't be
/// relied on to be consistent.
bool Linker::linkModules(Module &Dest, std::unique_ptr<Module> Src,
unsigned Flags) {
Linker L(Dest);
return L.linkInModule(std::move(Src), Flags);
}
std::unique_ptr<Module>
llvm::renameModuleForThinLTO(std::unique_ptr<Module> M,
const FunctionInfoIndex *Index) {
std::unique_ptr<llvm::Module> RenamedModule(
new llvm::Module(M->getModuleIdentifier(), M->getContext()));
Linker L(*RenamedModule.get());
if (L.linkInModule(std::move(M), llvm::Linker::Flags::None, Index))
return nullptr;
return RenamedModule;
}
//===----------------------------------------------------------------------===//
// C API.
//===----------------------------------------------------------------------===//
static void diagnosticHandler(const DiagnosticInfo &DI, void *C) {
auto *Message = reinterpret_cast<std::string *>(C);
raw_string_ostream Stream(*Message);
DiagnosticPrinterRawOStream DP(Stream);
DI.print(DP);
}
LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
LLVMLinkerMode Unused, char **OutMessages) {
Module *D = unwrap(Dest);
LLVMContext &Ctx = D->getContext();
LLVMContext::DiagnosticHandlerTy OldDiagnosticHandler =
Ctx.getDiagnosticHandler();
void *OldDiagnosticContext = Ctx.getDiagnosticContext();
std::string Message;
Ctx.setDiagnosticHandler(diagnosticHandler, &Message, true);
Linker L(*D);
Module *M = unwrap(Src);
LLVMBool Result = L.linkInModuleForCAPI(*M);
Ctx.setDiagnosticHandler(OldDiagnosticHandler, OldDiagnosticContext, true);
if (OutMessages && Result)
*OutMessages = strdup(Message.c_str());
return Result;
}
LLVMBool LLVMLinkModules2(LLVMModuleRef Dest, LLVMModuleRef Src) {
Module *D = unwrap(Dest);
std::unique_ptr<Module> M(unwrap(Src));
return Linker::linkModules(*D, std::move(M));
}
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