forked from OSchip/llvm-project
565 lines
20 KiB
C++
565 lines
20 KiB
C++
//===- InputFiles.cpp -----------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "InputFiles.h"
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#include "Config.h"
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#include "InputChunks.h"
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#include "InputEvent.h"
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#include "InputGlobal.h"
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#include "SymbolTable.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Memory.h"
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#include "lld/Common/Reproduce.h"
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#include "llvm/Object/Binary.h"
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#include "llvm/Object/Wasm.h"
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#include "llvm/Support/TarWriter.h"
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#include "llvm/Support/raw_ostream.h"
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#define DEBUG_TYPE "lld"
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using namespace llvm;
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using namespace llvm::object;
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using namespace llvm::wasm;
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namespace lld {
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// Returns a string in the format of "foo.o" or "foo.a(bar.o)".
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std::string toString(const wasm::InputFile *file) {
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if (!file)
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return "<internal>";
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if (file->archiveName.empty())
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return std::string(file->getName());
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return (file->archiveName + "(" + file->getName() + ")").str();
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}
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namespace wasm {
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std::unique_ptr<llvm::TarWriter> tar;
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Optional<MemoryBufferRef> readFile(StringRef path) {
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log("Loading: " + path);
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auto mbOrErr = MemoryBuffer::getFile(path);
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if (auto ec = mbOrErr.getError()) {
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error("cannot open " + path + ": " + ec.message());
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return None;
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}
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std::unique_ptr<MemoryBuffer> &mb = *mbOrErr;
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MemoryBufferRef mbref = mb->getMemBufferRef();
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make<std::unique_ptr<MemoryBuffer>>(std::move(mb)); // take MB ownership
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if (tar)
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tar->append(relativeToRoot(path), mbref.getBuffer());
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return mbref;
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}
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InputFile *createObjectFile(MemoryBufferRef mb,
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StringRef archiveName) {
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file_magic magic = identify_magic(mb.getBuffer());
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if (magic == file_magic::wasm_object) {
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std::unique_ptr<Binary> bin =
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CHECK(createBinary(mb), mb.getBufferIdentifier());
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auto *obj = cast<WasmObjectFile>(bin.get());
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if (obj->isSharedObject())
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return make<SharedFile>(mb);
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return make<ObjFile>(mb, archiveName);
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}
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if (magic == file_magic::bitcode)
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return make<BitcodeFile>(mb, archiveName);
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fatal("unknown file type: " + mb.getBufferIdentifier());
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}
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void ObjFile::dumpInfo() const {
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log("info for: " + toString(this) +
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"\n Symbols : " + Twine(symbols.size()) +
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"\n Function Imports : " + Twine(wasmObj->getNumImportedFunctions()) +
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"\n Global Imports : " + Twine(wasmObj->getNumImportedGlobals()) +
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"\n Event Imports : " + Twine(wasmObj->getNumImportedEvents()));
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}
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// Relocations contain either symbol or type indices. This function takes a
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// relocation and returns relocated index (i.e. translates from the input
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// symbol/type space to the output symbol/type space).
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uint32_t ObjFile::calcNewIndex(const WasmRelocation &reloc) const {
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if (reloc.Type == R_WASM_TYPE_INDEX_LEB) {
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assert(typeIsUsed[reloc.Index]);
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return typeMap[reloc.Index];
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}
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const Symbol *sym = symbols[reloc.Index];
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if (auto *ss = dyn_cast<SectionSymbol>(sym))
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sym = ss->getOutputSectionSymbol();
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return sym->getOutputSymbolIndex();
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}
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// Relocations can contain addend for combined sections. This function takes a
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// relocation and returns updated addend by offset in the output section.
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uint32_t ObjFile::calcNewAddend(const WasmRelocation &reloc) const {
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switch (reloc.Type) {
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case R_WASM_MEMORY_ADDR_LEB:
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case R_WASM_MEMORY_ADDR_SLEB:
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case R_WASM_MEMORY_ADDR_REL_SLEB:
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case R_WASM_MEMORY_ADDR_I32:
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case R_WASM_FUNCTION_OFFSET_I32:
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return reloc.Addend;
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case R_WASM_SECTION_OFFSET_I32:
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return getSectionSymbol(reloc.Index)->section->outputOffset + reloc.Addend;
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default:
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llvm_unreachable("unexpected relocation type");
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}
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}
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// Calculate the value we expect to find at the relocation location.
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// This is used as a sanity check before applying a relocation to a given
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// location. It is useful for catching bugs in the compiler and linker.
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uint32_t ObjFile::calcExpectedValue(const WasmRelocation &reloc) const {
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switch (reloc.Type) {
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case R_WASM_TABLE_INDEX_I32:
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case R_WASM_TABLE_INDEX_SLEB:
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case R_WASM_TABLE_INDEX_REL_SLEB: {
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const WasmSymbol &sym = wasmObj->syms()[reloc.Index];
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return tableEntries[sym.Info.ElementIndex];
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}
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case R_WASM_MEMORY_ADDR_SLEB:
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case R_WASM_MEMORY_ADDR_I32:
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case R_WASM_MEMORY_ADDR_LEB:
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case R_WASM_MEMORY_ADDR_REL_SLEB: {
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const WasmSymbol &sym = wasmObj->syms()[reloc.Index];
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if (sym.isUndefined())
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return 0;
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const WasmSegment &segment =
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wasmObj->dataSegments()[sym.Info.DataRef.Segment];
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return segment.Data.Offset.Value.Int32 + sym.Info.DataRef.Offset +
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reloc.Addend;
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}
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case R_WASM_FUNCTION_OFFSET_I32: {
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const WasmSymbol &sym = wasmObj->syms()[reloc.Index];
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InputFunction *f =
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functions[sym.Info.ElementIndex - wasmObj->getNumImportedFunctions()];
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return f->getFunctionInputOffset() + f->getFunctionCodeOffset() +
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reloc.Addend;
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}
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case R_WASM_SECTION_OFFSET_I32:
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return reloc.Addend;
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case R_WASM_TYPE_INDEX_LEB:
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return reloc.Index;
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case R_WASM_FUNCTION_INDEX_LEB:
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case R_WASM_GLOBAL_INDEX_LEB:
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case R_WASM_EVENT_INDEX_LEB: {
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const WasmSymbol &sym = wasmObj->syms()[reloc.Index];
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return sym.Info.ElementIndex;
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}
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default:
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llvm_unreachable("unknown relocation type");
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}
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}
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// Translate from the relocation's index into the final linked output value.
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uint32_t ObjFile::calcNewValue(const WasmRelocation &reloc) const {
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const Symbol* sym = nullptr;
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if (reloc.Type != R_WASM_TYPE_INDEX_LEB) {
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sym = symbols[reloc.Index];
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// We can end up with relocations against non-live symbols. For example
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// in debug sections.
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if ((isa<FunctionSymbol>(sym) || isa<DataSymbol>(sym)) && !sym->isLive())
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return 0;
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}
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switch (reloc.Type) {
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case R_WASM_TABLE_INDEX_I32:
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case R_WASM_TABLE_INDEX_SLEB:
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case R_WASM_TABLE_INDEX_REL_SLEB: {
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if (!getFunctionSymbol(reloc.Index)->hasTableIndex())
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return 0;
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uint32_t index = getFunctionSymbol(reloc.Index)->getTableIndex();
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if (reloc.Type == R_WASM_TABLE_INDEX_REL_SLEB)
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index -= config->tableBase;
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return index;
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}
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case R_WASM_MEMORY_ADDR_SLEB:
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case R_WASM_MEMORY_ADDR_I32:
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case R_WASM_MEMORY_ADDR_LEB:
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case R_WASM_MEMORY_ADDR_REL_SLEB:
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if (isa<UndefinedData>(sym) || sym->isUndefWeak())
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return 0;
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return cast<DefinedData>(sym)->getVirtualAddress() + reloc.Addend;
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case R_WASM_TYPE_INDEX_LEB:
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return typeMap[reloc.Index];
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case R_WASM_FUNCTION_INDEX_LEB:
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return getFunctionSymbol(reloc.Index)->getFunctionIndex();
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case R_WASM_GLOBAL_INDEX_LEB:
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if (auto gs = dyn_cast<GlobalSymbol>(sym))
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return gs->getGlobalIndex();
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return sym->getGOTIndex();
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case R_WASM_EVENT_INDEX_LEB:
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return getEventSymbol(reloc.Index)->getEventIndex();
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case R_WASM_FUNCTION_OFFSET_I32: {
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auto *f = cast<DefinedFunction>(sym);
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return f->function->outputOffset + f->function->getFunctionCodeOffset() +
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reloc.Addend;
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}
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case R_WASM_SECTION_OFFSET_I32:
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return getSectionSymbol(reloc.Index)->section->outputOffset + reloc.Addend;
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default:
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llvm_unreachable("unknown relocation type");
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}
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}
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template <class T>
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static void setRelocs(const std::vector<T *> &chunks,
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const WasmSection *section) {
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if (!section)
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return;
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ArrayRef<WasmRelocation> relocs = section->Relocations;
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assert(std::is_sorted(relocs.begin(), relocs.end(),
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[](const WasmRelocation &r1, const WasmRelocation &r2) {
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return r1.Offset < r2.Offset;
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}));
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assert(std::is_sorted(
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chunks.begin(), chunks.end(), [](InputChunk *c1, InputChunk *c2) {
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return c1->getInputSectionOffset() < c2->getInputSectionOffset();
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}));
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auto relocsNext = relocs.begin();
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auto relocsEnd = relocs.end();
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auto relocLess = [](const WasmRelocation &r, uint32_t val) {
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return r.Offset < val;
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};
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for (InputChunk *c : chunks) {
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auto relocsStart = std::lower_bound(relocsNext, relocsEnd,
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c->getInputSectionOffset(), relocLess);
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relocsNext = std::lower_bound(
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relocsStart, relocsEnd, c->getInputSectionOffset() + c->getInputSize(),
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relocLess);
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c->setRelocations(ArrayRef<WasmRelocation>(relocsStart, relocsNext));
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}
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}
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void ObjFile::parse(bool ignoreComdats) {
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// Parse a memory buffer as a wasm file.
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LLVM_DEBUG(dbgs() << "Parsing object: " << toString(this) << "\n");
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std::unique_ptr<Binary> bin = CHECK(createBinary(mb), toString(this));
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auto *obj = dyn_cast<WasmObjectFile>(bin.get());
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if (!obj)
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fatal(toString(this) + ": not a wasm file");
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if (!obj->isRelocatableObject())
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fatal(toString(this) + ": not a relocatable wasm file");
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bin.release();
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wasmObj.reset(obj);
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// Build up a map of function indices to table indices for use when
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// verifying the existing table index relocations
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uint32_t totalFunctions =
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wasmObj->getNumImportedFunctions() + wasmObj->functions().size();
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tableEntries.resize(totalFunctions);
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for (const WasmElemSegment &seg : wasmObj->elements()) {
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if (seg.Offset.Opcode != WASM_OPCODE_I32_CONST)
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fatal(toString(this) + ": invalid table elements");
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uint32_t offset = seg.Offset.Value.Int32;
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for (uint32_t index = 0; index < seg.Functions.size(); index++) {
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uint32_t functionIndex = seg.Functions[index];
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tableEntries[functionIndex] = offset + index;
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}
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}
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uint32_t sectionIndex = 0;
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// Bool for each symbol, true if called directly. This allows us to implement
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// a weaker form of signature checking where undefined functions that are not
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// called directly (i.e. only address taken) don't have to match the defined
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// function's signature. We cannot do this for directly called functions
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// because those signatures are checked at validation times.
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// See https://bugs.llvm.org/show_bug.cgi?id=40412
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std::vector<bool> isCalledDirectly(wasmObj->getNumberOfSymbols(), false);
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for (const SectionRef &sec : wasmObj->sections()) {
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const WasmSection §ion = wasmObj->getWasmSection(sec);
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// Wasm objects can have at most one code and one data section.
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if (section.Type == WASM_SEC_CODE) {
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assert(!codeSection);
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codeSection = §ion;
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} else if (section.Type == WASM_SEC_DATA) {
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assert(!dataSection);
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dataSection = §ion;
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} else if (section.Type == WASM_SEC_CUSTOM) {
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customSections.emplace_back(make<InputSection>(section, this));
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customSections.back()->setRelocations(section.Relocations);
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customSectionsByIndex[sectionIndex] = customSections.back();
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}
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sectionIndex++;
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// Scans relocations to determine if a function symbol is called directly.
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for (const WasmRelocation &reloc : section.Relocations)
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if (reloc.Type == R_WASM_FUNCTION_INDEX_LEB)
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isCalledDirectly[reloc.Index] = true;
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}
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typeMap.resize(getWasmObj()->types().size());
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typeIsUsed.resize(getWasmObj()->types().size(), false);
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ArrayRef<StringRef> comdats = wasmObj->linkingData().Comdats;
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for (StringRef comdat : comdats) {
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bool isNew = ignoreComdats || symtab->addComdat(comdat);
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keptComdats.push_back(isNew);
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}
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// Populate `Segments`.
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for (const WasmSegment &s : wasmObj->dataSegments()) {
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auto* seg = make<InputSegment>(s, this);
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seg->discarded = isExcludedByComdat(seg);
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segments.emplace_back(seg);
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}
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setRelocs(segments, dataSection);
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// Populate `Functions`.
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ArrayRef<WasmFunction> funcs = wasmObj->functions();
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ArrayRef<uint32_t> funcTypes = wasmObj->functionTypes();
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ArrayRef<WasmSignature> types = wasmObj->types();
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functions.reserve(funcs.size());
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for (size_t i = 0, e = funcs.size(); i != e; ++i) {
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auto* func = make<InputFunction>(types[funcTypes[i]], &funcs[i], this);
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func->discarded = isExcludedByComdat(func);
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functions.emplace_back(func);
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}
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setRelocs(functions, codeSection);
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// Populate `Globals`.
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for (const WasmGlobal &g : wasmObj->globals())
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globals.emplace_back(make<InputGlobal>(g, this));
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// Populate `Events`.
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for (const WasmEvent &e : wasmObj->events())
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events.emplace_back(make<InputEvent>(types[e.Type.SigIndex], e, this));
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// Populate `Symbols` based on the symbols in the object.
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symbols.reserve(wasmObj->getNumberOfSymbols());
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for (const SymbolRef &sym : wasmObj->symbols()) {
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const WasmSymbol &wasmSym = wasmObj->getWasmSymbol(sym.getRawDataRefImpl());
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if (wasmSym.isDefined()) {
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// createDefined may fail if the symbol is comdat excluded in which case
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// we fall back to creating an undefined symbol
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if (Symbol *d = createDefined(wasmSym)) {
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symbols.push_back(d);
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continue;
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}
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}
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size_t idx = symbols.size();
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symbols.push_back(createUndefined(wasmSym, isCalledDirectly[idx]));
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}
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}
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bool ObjFile::isExcludedByComdat(InputChunk *chunk) const {
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uint32_t c = chunk->getComdat();
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if (c == UINT32_MAX)
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return false;
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return !keptComdats[c];
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}
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FunctionSymbol *ObjFile::getFunctionSymbol(uint32_t index) const {
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return cast<FunctionSymbol>(symbols[index]);
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}
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GlobalSymbol *ObjFile::getGlobalSymbol(uint32_t index) const {
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return cast<GlobalSymbol>(symbols[index]);
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}
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EventSymbol *ObjFile::getEventSymbol(uint32_t index) const {
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return cast<EventSymbol>(symbols[index]);
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}
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SectionSymbol *ObjFile::getSectionSymbol(uint32_t index) const {
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return cast<SectionSymbol>(symbols[index]);
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}
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DataSymbol *ObjFile::getDataSymbol(uint32_t index) const {
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return cast<DataSymbol>(symbols[index]);
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}
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Symbol *ObjFile::createDefined(const WasmSymbol &sym) {
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StringRef name = sym.Info.Name;
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uint32_t flags = sym.Info.Flags;
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switch (sym.Info.Kind) {
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case WASM_SYMBOL_TYPE_FUNCTION: {
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InputFunction *func =
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functions[sym.Info.ElementIndex - wasmObj->getNumImportedFunctions()];
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if (sym.isBindingLocal())
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return make<DefinedFunction>(name, flags, this, func);
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if (func->discarded)
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return nullptr;
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return symtab->addDefinedFunction(name, flags, this, func);
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}
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case WASM_SYMBOL_TYPE_DATA: {
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InputSegment *seg = segments[sym.Info.DataRef.Segment];
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uint32_t offset = sym.Info.DataRef.Offset;
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uint32_t size = sym.Info.DataRef.Size;
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if (sym.isBindingLocal())
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return make<DefinedData>(name, flags, this, seg, offset, size);
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if (seg->discarded)
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return nullptr;
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return symtab->addDefinedData(name, flags, this, seg, offset, size);
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}
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case WASM_SYMBOL_TYPE_GLOBAL: {
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InputGlobal *global =
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globals[sym.Info.ElementIndex - wasmObj->getNumImportedGlobals()];
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if (sym.isBindingLocal())
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return make<DefinedGlobal>(name, flags, this, global);
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return symtab->addDefinedGlobal(name, flags, this, global);
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}
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case WASM_SYMBOL_TYPE_SECTION: {
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InputSection *section = customSectionsByIndex[sym.Info.ElementIndex];
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assert(sym.isBindingLocal());
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return make<SectionSymbol>(flags, section, this);
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}
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case WASM_SYMBOL_TYPE_EVENT: {
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InputEvent *event =
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events[sym.Info.ElementIndex - wasmObj->getNumImportedEvents()];
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if (sym.isBindingLocal())
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return make<DefinedEvent>(name, flags, this, event);
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return symtab->addDefinedEvent(name, flags, this, event);
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}
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}
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llvm_unreachable("unknown symbol kind");
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}
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Symbol *ObjFile::createUndefined(const WasmSymbol &sym, bool isCalledDirectly) {
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StringRef name = sym.Info.Name;
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uint32_t flags = sym.Info.Flags | WASM_SYMBOL_UNDEFINED;
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switch (sym.Info.Kind) {
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case WASM_SYMBOL_TYPE_FUNCTION:
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if (sym.isBindingLocal())
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return make<UndefinedFunction>(name, sym.Info.ImportName,
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sym.Info.ImportModule, flags, this,
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sym.Signature, isCalledDirectly);
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return symtab->addUndefinedFunction(name, sym.Info.ImportName,
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sym.Info.ImportModule, flags, this,
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sym.Signature, isCalledDirectly);
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case WASM_SYMBOL_TYPE_DATA:
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if (sym.isBindingLocal())
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return make<UndefinedData>(name, flags, this);
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return symtab->addUndefinedData(name, flags, this);
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case WASM_SYMBOL_TYPE_GLOBAL:
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if (sym.isBindingLocal())
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|
return make<UndefinedGlobal>(name, sym.Info.ImportName,
|
|
sym.Info.ImportModule, flags, this,
|
|
sym.GlobalType);
|
|
return symtab->addUndefinedGlobal(name, sym.Info.ImportName,
|
|
sym.Info.ImportModule, flags, this,
|
|
sym.GlobalType);
|
|
case WASM_SYMBOL_TYPE_SECTION:
|
|
llvm_unreachable("section symbols cannot be undefined");
|
|
}
|
|
llvm_unreachable("unknown symbol kind");
|
|
}
|
|
|
|
void ArchiveFile::parse() {
|
|
// Parse a MemoryBufferRef as an archive file.
|
|
LLVM_DEBUG(dbgs() << "Parsing library: " << toString(this) << "\n");
|
|
file = CHECK(Archive::create(mb), toString(this));
|
|
|
|
// Read the symbol table to construct Lazy symbols.
|
|
int count = 0;
|
|
for (const Archive::Symbol &sym : file->symbols()) {
|
|
symtab->addLazy(this, &sym);
|
|
++count;
|
|
}
|
|
LLVM_DEBUG(dbgs() << "Read " << count << " symbols\n");
|
|
}
|
|
|
|
void ArchiveFile::addMember(const Archive::Symbol *sym) {
|
|
const Archive::Child &c =
|
|
CHECK(sym->getMember(),
|
|
"could not get the member for symbol " + sym->getName());
|
|
|
|
// Don't try to load the same member twice (this can happen when members
|
|
// mutually reference each other).
|
|
if (!seen.insert(c.getChildOffset()).second)
|
|
return;
|
|
|
|
LLVM_DEBUG(dbgs() << "loading lazy: " << sym->getName() << "\n");
|
|
LLVM_DEBUG(dbgs() << "from archive: " << toString(this) << "\n");
|
|
|
|
MemoryBufferRef mb =
|
|
CHECK(c.getMemoryBufferRef(),
|
|
"could not get the buffer for the member defining symbol " +
|
|
sym->getName());
|
|
|
|
InputFile *obj = createObjectFile(mb, getName());
|
|
symtab->addFile(obj);
|
|
}
|
|
|
|
static uint8_t mapVisibility(GlobalValue::VisibilityTypes gvVisibility) {
|
|
switch (gvVisibility) {
|
|
case GlobalValue::DefaultVisibility:
|
|
return WASM_SYMBOL_VISIBILITY_DEFAULT;
|
|
case GlobalValue::HiddenVisibility:
|
|
case GlobalValue::ProtectedVisibility:
|
|
return WASM_SYMBOL_VISIBILITY_HIDDEN;
|
|
}
|
|
llvm_unreachable("unknown visibility");
|
|
}
|
|
|
|
static Symbol *createBitcodeSymbol(const std::vector<bool> &keptComdats,
|
|
const lto::InputFile::Symbol &objSym,
|
|
BitcodeFile &f) {
|
|
StringRef name = saver.save(objSym.getName());
|
|
|
|
uint32_t flags = objSym.isWeak() ? WASM_SYMBOL_BINDING_WEAK : 0;
|
|
flags |= mapVisibility(objSym.getVisibility());
|
|
|
|
int c = objSym.getComdatIndex();
|
|
bool excludedByComdat = c != -1 && !keptComdats[c];
|
|
|
|
if (objSym.isUndefined() || excludedByComdat) {
|
|
flags |= WASM_SYMBOL_UNDEFINED;
|
|
if (objSym.isExecutable())
|
|
return symtab->addUndefinedFunction(name, None, None, flags, &f, nullptr,
|
|
true);
|
|
return symtab->addUndefinedData(name, flags, &f);
|
|
}
|
|
|
|
if (objSym.isExecutable())
|
|
return symtab->addDefinedFunction(name, flags, &f, nullptr);
|
|
return symtab->addDefinedData(name, flags, &f, nullptr, 0, 0);
|
|
}
|
|
|
|
bool BitcodeFile::doneLTO = false;
|
|
|
|
void BitcodeFile::parse() {
|
|
if (doneLTO) {
|
|
error(toString(mb.getBufferIdentifier()) +
|
|
": attempt to add bitcode file after LTO.");
|
|
return;
|
|
}
|
|
|
|
obj = check(lto::InputFile::create(MemoryBufferRef(
|
|
mb.getBuffer(), saver.save(archiveName + mb.getBufferIdentifier()))));
|
|
Triple t(obj->getTargetTriple());
|
|
if (t.getArch() != Triple::wasm32) {
|
|
error(toString(mb.getBufferIdentifier()) + ": machine type must be wasm32");
|
|
return;
|
|
}
|
|
std::vector<bool> keptComdats;
|
|
for (StringRef s : obj->getComdatTable())
|
|
keptComdats.push_back(symtab->addComdat(s));
|
|
|
|
for (const lto::InputFile::Symbol &objSym : obj->symbols())
|
|
symbols.push_back(createBitcodeSymbol(keptComdats, objSym, *this));
|
|
}
|
|
|
|
} // namespace wasm
|
|
} // namespace lld
|