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//===----- COFFLinkGraphBuilder.h - COFF LinkGraph builder ----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Generic COFF LinkGraph building code.
//
//===----------------------------------------------------------------------===//
#ifndef LIB_EXECUTIONENGINE_JITLINK_COFFLINKGRAPHBUILDER_H
#define LIB_EXECUTIONENGINE_JITLINK_COFFLINKGRAPHBUILDER_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ExecutionEngine/JITLink/JITLink.h"
#include "llvm/Object/COFF.h"
#include "COFFDirectiveParser.h"
#include "EHFrameSupportImpl.h"
#include "JITLinkGeneric.h"
#define DEBUG_TYPE "jitlink"
#include <list>
namespace llvm {
namespace jitlink {
class COFFLinkGraphBuilder {
public:
virtual ~COFFLinkGraphBuilder();
Expected<std::unique_ptr<LinkGraph>> buildGraph();
protected:
using COFFSectionIndex = int32_t;
using COFFSymbolIndex = int32_t;
COFFLinkGraphBuilder(const object::COFFObjectFile &Obj, Triple TT,
SubtargetFeatures Features,
LinkGraph::GetEdgeKindNameFunction GetEdgeKindName);
LinkGraph &getGraph() const { return *G; }
const object::COFFObjectFile &getObject() const { return Obj; }
virtual Error addRelocations() = 0;
Error graphifySections();
Error graphifySymbols();
void setGraphSymbol(COFFSectionIndex SecIndex, COFFSymbolIndex SymIndex,
Symbol &Sym) {
assert(!GraphSymbols[SymIndex] && "Duplicate symbol at index");
GraphSymbols[SymIndex] = &Sym;
if (!COFF::isReservedSectionNumber(SecIndex))
SymbolSets[SecIndex].insert({Sym.getOffset(), &Sym});
}
Symbol *getGraphSymbol(COFFSymbolIndex SymIndex) const {
if (SymIndex < 0 ||
SymIndex >= static_cast<COFFSymbolIndex>(GraphSymbols.size()))
return nullptr;
return GraphSymbols[SymIndex];
}
void setGraphBlock(COFFSectionIndex SecIndex, Block *B) {
assert(!GraphBlocks[SecIndex] && "Duplicate section at index");
assert(!COFF::isReservedSectionNumber(SecIndex) && "Invalid section index");
GraphBlocks[SecIndex] = B;
}
Block *getGraphBlock(COFFSectionIndex SecIndex) const {
if (SecIndex <= 0 ||
SecIndex >= static_cast<COFFSectionIndex>(GraphSymbols.size()))
return nullptr;
return GraphBlocks[SecIndex];
}
object::COFFObjectFile::section_iterator_range sections() const {
return Obj.sections();
}
/// Traverse all matching relocation records in the given section. The handler
/// function Func should be callable with this signature:
/// Error(const object::RelocationRef&,
/// const object::SectionRef&, Section &)
///
template <typename RelocHandlerFunction>
Error forEachRelocation(const object::SectionRef &RelSec,
RelocHandlerFunction &&Func,
bool ProcessDebugSections = false);
/// Traverse all matching relocation records in the given section. Convenience
/// wrapper to allow passing a member function for the handler.
///
template <typename ClassT, typename RelocHandlerMethod>
Error forEachRelocation(const object::SectionRef &RelSec, ClassT *Instance,
RelocHandlerMethod &&Method,
bool ProcessDebugSections = false) {
return forEachRelocation(
RelSec,
[Instance, Method](const auto &Rel, const auto &Target, auto &GS) {
return (Instance->*Method)(Rel, Target, GS);
},
ProcessDebugSections);
}
private:
// Pending comdat symbol export that is initiated by the first symbol of
// COMDAT sequence.
struct ComdatExportRequest {
COFFSymbolIndex SymbolIndex;
jitlink::Linkage Linkage;
orc::ExecutorAddrDiff Size;
};
std::vector<std::optional<ComdatExportRequest>> PendingComdatExports;
// This represents a pending request to create a weak external symbol with a
// name.
struct WeakExternalRequest {
COFFSymbolIndex Alias;
COFFSymbolIndex Target;
uint32_t Characteristics;
StringRef SymbolName;
};
std::vector<WeakExternalRequest> WeakExternalRequests;
// Per COFF section jitlink symbol set sorted by offset.
// Used for calculating implicit size of defined symbols.
using SymbolSet = std::set<std::pair<orc::ExecutorAddrDiff, Symbol *>>;
std::vector<SymbolSet> SymbolSets;
Section &getCommonSection();
Symbol *createExternalSymbol(COFFSymbolIndex SymIndex, StringRef SymbolName,
object::COFFSymbolRef Symbol,
const object::coff_section *Section);
Expected<Symbol *> createAliasSymbol(StringRef SymbolName, Linkage L, Scope S,
Symbol &Target);
Expected<Symbol *> createDefinedSymbol(COFFSymbolIndex SymIndex,
StringRef SymbolName,
object::COFFSymbolRef Symbol,
const object::coff_section *Section);
Expected<Symbol *> createCOMDATExportRequest(
COFFSymbolIndex SymIndex, object::COFFSymbolRef Symbol,
const object::coff_aux_section_definition *Definition);
Expected<Symbol *> exportCOMDATSymbol(COFFSymbolIndex SymIndex,
StringRef SymbolName,
object::COFFSymbolRef Symbol);
Error handleDirectiveSection(StringRef Str);
Error flushWeakAliasRequests();
Error handleAlternateNames();
Error calculateImplicitSizeOfSymbols();
static uint64_t getSectionAddress(const object::COFFObjectFile &Obj,
const object::coff_section *Section);
static uint64_t getSectionSize(const object::COFFObjectFile &Obj,
const object::coff_section *Section);
static bool isComdatSection(const object::coff_section *Section);
static unsigned getPointerSize(const object::COFFObjectFile &Obj);
static support::endianness getEndianness(const object::COFFObjectFile &Obj);
static StringRef getDLLImportStubPrefix() { return "__imp_"; }
static StringRef getDirectiveSectionName() { return ".drectve"; }
StringRef getCOFFSectionName(COFFSectionIndex SectionIndex,
const object::coff_section *Sec,
object::COFFSymbolRef Sym);
const object::COFFObjectFile &Obj;
std::unique_ptr<LinkGraph> G;
COFFDirectiveParser DirectiveParser;
Section *CommonSection = nullptr;
std::vector<Block *> GraphBlocks;
std::vector<Symbol *> GraphSymbols;
DenseMap<StringRef, StringRef> AlternateNames;
DenseMap<StringRef, Symbol *> ExternalSymbols;
DenseMap<StringRef, Symbol *> DefinedSymbols;
};
template <typename RelocHandlerFunction>
Error COFFLinkGraphBuilder::forEachRelocation(const object::SectionRef &RelSec,
RelocHandlerFunction &&Func,
bool ProcessDebugSections) {
auto COFFRelSect = Obj.getCOFFSection(RelSec);
// Target sections have names in valid COFF object files.
Expected<StringRef> Name = Obj.getSectionName(COFFRelSect);
if (!Name)
return Name.takeError();
// Skip the unhandled metadata sections.
if (*Name == ".voltbl")
return Error::success();
LLVM_DEBUG(dbgs() << " " << *Name << ":\n");
// Lookup the link-graph node corresponding to the target section name.
auto *BlockToFix = getGraphBlock(RelSec.getIndex() + 1);
if (!BlockToFix)
return make_error<StringError>(
"Referencing a section that wasn't added to the graph: " + *Name,
inconvertibleErrorCode());
// Let the callee process relocation entries one by one.
for (const auto &R : RelSec.relocations())
if (Error Err = Func(R, RelSec, *BlockToFix))
return Err;
LLVM_DEBUG(dbgs() << "\n");
return Error::success();
}
} // end namespace jitlink
} // end namespace llvm
#endif // LIB_EXECUTIONENGINE_JITLINK_COFFLINKGRAPHBUILDER_H
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