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0c7127a873
Debug info sections need R_WASM_FUNCTION_OFFSET_I32 relocs (with FK_Data_4 fixup kinds) to refer to functions (instead of R_WASM_TABLE_INDEX as is used in data sections). Usually this is done in a convoluted way, with unnamed temp data symbols which target the start of the function, in which case WasmObjectWriter::recordRelocation converts it to use the section symbol instead. However in some cases the function can actually be undefined; in this case the dwarf generator uses the function symbol (a named undefined function symbol) instead. In that case the section-symbol transform doesn't work and we need to generate the correct reloc type a different way. In this change WebAssemblyWasmObjectWriter::getRelocType takes the fixup section type into account to choose the correct reloc type. Fixes PR50408 Differential Revision: https://reviews.llvm.org/D103557
1925 lines
68 KiB
C++
1925 lines
68 KiB
C++
//===- lib/MC/WasmObjectWriter.cpp - Wasm File Writer ---------------------===//
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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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//
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// This file implements Wasm object file writer information.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/BinaryFormat/Wasm.h"
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#include "llvm/BinaryFormat/WasmTraits.h"
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#include "llvm/Config/llvm-config.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAsmLayout.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCFixupKindInfo.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCSectionWasm.h"
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#include "llvm/MC/MCSymbolWasm.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/MC/MCWasmObjectWriter.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/EndianStream.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/LEB128.h"
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#include "llvm/Support/StringSaver.h"
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#include <vector>
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using namespace llvm;
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#define DEBUG_TYPE "mc"
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namespace {
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// When we create the indirect function table we start at 1, so that there is
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// and empty slot at 0 and therefore calling a null function pointer will trap.
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static const uint32_t InitialTableOffset = 1;
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// For patching purposes, we need to remember where each section starts, both
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// for patching up the section size field, and for patching up references to
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// locations within the section.
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struct SectionBookkeeping {
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// Where the size of the section is written.
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uint64_t SizeOffset;
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// Where the section header ends (without custom section name).
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uint64_t PayloadOffset;
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// Where the contents of the section starts.
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uint64_t ContentsOffset;
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uint32_t Index;
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};
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// A wasm data segment. A wasm binary contains only a single data section
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// but that can contain many segments, each with their own virtual location
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// in memory. Each MCSection data created by llvm is modeled as its own
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// wasm data segment.
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struct WasmDataSegment {
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MCSectionWasm *Section;
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StringRef Name;
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uint32_t InitFlags;
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uint64_t Offset;
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uint32_t Alignment;
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uint32_t LinkingFlags;
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SmallVector<char, 4> Data;
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};
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// A wasm function to be written into the function section.
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struct WasmFunction {
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uint32_t SigIndex;
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const MCSymbolWasm *Sym;
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};
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// A wasm global to be written into the global section.
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struct WasmGlobal {
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wasm::WasmGlobalType Type;
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uint64_t InitialValue;
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};
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// Information about a single item which is part of a COMDAT. For each data
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// segment or function which is in the COMDAT, there is a corresponding
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// WasmComdatEntry.
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struct WasmComdatEntry {
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unsigned Kind;
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uint32_t Index;
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};
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// Information about a single relocation.
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struct WasmRelocationEntry {
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uint64_t Offset; // Where is the relocation.
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const MCSymbolWasm *Symbol; // The symbol to relocate with.
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int64_t Addend; // A value to add to the symbol.
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unsigned Type; // The type of the relocation.
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const MCSectionWasm *FixupSection; // The section the relocation is targeting.
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WasmRelocationEntry(uint64_t Offset, const MCSymbolWasm *Symbol,
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int64_t Addend, unsigned Type,
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const MCSectionWasm *FixupSection)
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: Offset(Offset), Symbol(Symbol), Addend(Addend), Type(Type),
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FixupSection(FixupSection) {}
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bool hasAddend() const { return wasm::relocTypeHasAddend(Type); }
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void print(raw_ostream &Out) const {
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Out << wasm::relocTypetoString(Type) << " Off=" << Offset
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<< ", Sym=" << *Symbol << ", Addend=" << Addend
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<< ", FixupSection=" << FixupSection->getName();
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
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#endif
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};
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static const uint32_t InvalidIndex = -1;
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struct WasmCustomSection {
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StringRef Name;
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MCSectionWasm *Section;
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uint32_t OutputContentsOffset;
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uint32_t OutputIndex;
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WasmCustomSection(StringRef Name, MCSectionWasm *Section)
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: Name(Name), Section(Section), OutputContentsOffset(0),
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OutputIndex(InvalidIndex) {}
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};
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#if !defined(NDEBUG)
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raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) {
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Rel.print(OS);
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return OS;
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}
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#endif
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// Write X as an (unsigned) LEB value at offset Offset in Stream, padded
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// to allow patching.
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template <int W>
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void writePatchableLEB(raw_pwrite_stream &Stream, uint64_t X, uint64_t Offset) {
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uint8_t Buffer[W];
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unsigned SizeLen = encodeULEB128(X, Buffer, W);
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assert(SizeLen == W);
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Stream.pwrite((char *)Buffer, SizeLen, Offset);
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}
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// Write X as an signed LEB value at offset Offset in Stream, padded
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// to allow patching.
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template <int W>
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void writePatchableSLEB(raw_pwrite_stream &Stream, int64_t X, uint64_t Offset) {
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uint8_t Buffer[W];
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unsigned SizeLen = encodeSLEB128(X, Buffer, W);
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assert(SizeLen == W);
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Stream.pwrite((char *)Buffer, SizeLen, Offset);
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}
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// Write X as a plain integer value at offset Offset in Stream.
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static void patchI32(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) {
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uint8_t Buffer[4];
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support::endian::write32le(Buffer, X);
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Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset);
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}
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static void patchI64(raw_pwrite_stream &Stream, uint64_t X, uint64_t Offset) {
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uint8_t Buffer[8];
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support::endian::write64le(Buffer, X);
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Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset);
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}
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bool isDwoSection(const MCSection &Sec) {
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return Sec.getName().endswith(".dwo");
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}
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class WasmObjectWriter : public MCObjectWriter {
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support::endian::Writer *W;
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/// The target specific Wasm writer instance.
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std::unique_ptr<MCWasmObjectTargetWriter> TargetObjectWriter;
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// Relocations for fixing up references in the code section.
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std::vector<WasmRelocationEntry> CodeRelocations;
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// Relocations for fixing up references in the data section.
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std::vector<WasmRelocationEntry> DataRelocations;
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// Index values to use for fixing up call_indirect type indices.
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// Maps function symbols to the index of the type of the function
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DenseMap<const MCSymbolWasm *, uint32_t> TypeIndices;
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// Maps function symbols to the table element index space. Used
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// for TABLE_INDEX relocation types (i.e. address taken functions).
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DenseMap<const MCSymbolWasm *, uint32_t> TableIndices;
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// Maps function/global/table symbols to the
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// function/global/table/tag/section index space.
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DenseMap<const MCSymbolWasm *, uint32_t> WasmIndices;
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DenseMap<const MCSymbolWasm *, uint32_t> GOTIndices;
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// Maps data symbols to the Wasm segment and offset/size with the segment.
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DenseMap<const MCSymbolWasm *, wasm::WasmDataReference> DataLocations;
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// Stores output data (index, relocations, content offset) for custom
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// section.
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std::vector<WasmCustomSection> CustomSections;
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std::unique_ptr<WasmCustomSection> ProducersSection;
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std::unique_ptr<WasmCustomSection> TargetFeaturesSection;
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// Relocations for fixing up references in the custom sections.
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DenseMap<const MCSectionWasm *, std::vector<WasmRelocationEntry>>
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CustomSectionsRelocations;
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// Map from section to defining function symbol.
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DenseMap<const MCSection *, const MCSymbol *> SectionFunctions;
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DenseMap<wasm::WasmSignature, uint32_t> SignatureIndices;
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SmallVector<wasm::WasmSignature, 4> Signatures;
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SmallVector<WasmDataSegment, 4> DataSegments;
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unsigned NumFunctionImports = 0;
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unsigned NumGlobalImports = 0;
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unsigned NumTableImports = 0;
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unsigned NumTagImports = 0;
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uint32_t SectionCount = 0;
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enum class DwoMode {
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AllSections,
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NonDwoOnly,
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DwoOnly,
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};
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bool IsSplitDwarf = false;
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raw_pwrite_stream *OS = nullptr;
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raw_pwrite_stream *DwoOS = nullptr;
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// TargetObjectWriter wranppers.
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bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
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bool isEmscripten() const { return TargetObjectWriter->isEmscripten(); }
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void startSection(SectionBookkeeping &Section, unsigned SectionId);
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void startCustomSection(SectionBookkeeping &Section, StringRef Name);
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void endSection(SectionBookkeeping &Section);
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public:
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WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
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raw_pwrite_stream &OS_)
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: TargetObjectWriter(std::move(MOTW)), OS(&OS_) {}
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WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
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raw_pwrite_stream &OS_, raw_pwrite_stream &DwoOS_)
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: TargetObjectWriter(std::move(MOTW)), IsSplitDwarf(true), OS(&OS_),
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DwoOS(&DwoOS_) {}
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private:
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void reset() override {
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CodeRelocations.clear();
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DataRelocations.clear();
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TypeIndices.clear();
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WasmIndices.clear();
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GOTIndices.clear();
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TableIndices.clear();
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DataLocations.clear();
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CustomSections.clear();
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ProducersSection.reset();
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TargetFeaturesSection.reset();
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CustomSectionsRelocations.clear();
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SignatureIndices.clear();
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Signatures.clear();
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DataSegments.clear();
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SectionFunctions.clear();
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NumFunctionImports = 0;
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NumGlobalImports = 0;
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NumTableImports = 0;
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MCObjectWriter::reset();
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}
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void writeHeader(const MCAssembler &Asm);
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void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
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const MCFragment *Fragment, const MCFixup &Fixup,
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MCValue Target, uint64_t &FixedValue) override;
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void executePostLayoutBinding(MCAssembler &Asm,
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const MCAsmLayout &Layout) override;
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void prepareImports(SmallVectorImpl<wasm::WasmImport> &Imports,
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MCAssembler &Asm, const MCAsmLayout &Layout);
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uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
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uint64_t writeOneObject(MCAssembler &Asm, const MCAsmLayout &Layout,
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DwoMode Mode);
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void writeString(const StringRef Str) {
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encodeULEB128(Str.size(), W->OS);
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W->OS << Str;
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}
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void writeI32(int32_t val) {
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char Buffer[4];
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support::endian::write32le(Buffer, val);
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W->OS.write(Buffer, sizeof(Buffer));
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}
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void writeI64(int64_t val) {
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char Buffer[8];
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support::endian::write64le(Buffer, val);
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W->OS.write(Buffer, sizeof(Buffer));
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}
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void writeValueType(wasm::ValType Ty) { W->OS << static_cast<char>(Ty); }
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void writeTypeSection(ArrayRef<wasm::WasmSignature> Signatures);
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void writeImportSection(ArrayRef<wasm::WasmImport> Imports, uint64_t DataSize,
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uint32_t NumElements);
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void writeFunctionSection(ArrayRef<WasmFunction> Functions);
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void writeExportSection(ArrayRef<wasm::WasmExport> Exports);
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void writeElemSection(const MCSymbolWasm *IndirectFunctionTable,
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ArrayRef<uint32_t> TableElems);
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void writeDataCountSection();
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uint32_t writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
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ArrayRef<WasmFunction> Functions);
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uint32_t writeDataSection(const MCAsmLayout &Layout);
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void writeTagSection(ArrayRef<wasm::WasmTagType> Tags);
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void writeGlobalSection(ArrayRef<wasm::WasmGlobal> Globals);
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void writeTableSection(ArrayRef<wasm::WasmTable> Tables);
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void writeRelocSection(uint32_t SectionIndex, StringRef Name,
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std::vector<WasmRelocationEntry> &Relocations);
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void writeLinkingMetaDataSection(
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ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
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ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs,
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const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats);
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void writeCustomSection(WasmCustomSection &CustomSection,
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const MCAssembler &Asm, const MCAsmLayout &Layout);
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void writeCustomRelocSections();
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uint64_t getProvisionalValue(const WasmRelocationEntry &RelEntry,
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const MCAsmLayout &Layout);
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void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations,
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uint64_t ContentsOffset, const MCAsmLayout &Layout);
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uint32_t getRelocationIndexValue(const WasmRelocationEntry &RelEntry);
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uint32_t getFunctionType(const MCSymbolWasm &Symbol);
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uint32_t getTagType(const MCSymbolWasm &Symbol);
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void registerFunctionType(const MCSymbolWasm &Symbol);
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void registerTagType(const MCSymbolWasm &Symbol);
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};
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} // end anonymous namespace
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// Write out a section header and a patchable section size field.
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void WasmObjectWriter::startSection(SectionBookkeeping &Section,
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unsigned SectionId) {
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LLVM_DEBUG(dbgs() << "startSection " << SectionId << "\n");
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W->OS << char(SectionId);
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Section.SizeOffset = W->OS.tell();
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// The section size. We don't know the size yet, so reserve enough space
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// for any 32-bit value; we'll patch it later.
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encodeULEB128(0, W->OS, 5);
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// The position where the section starts, for measuring its size.
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Section.ContentsOffset = W->OS.tell();
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Section.PayloadOffset = W->OS.tell();
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Section.Index = SectionCount++;
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}
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void WasmObjectWriter::startCustomSection(SectionBookkeeping &Section,
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StringRef Name) {
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LLVM_DEBUG(dbgs() << "startCustomSection " << Name << "\n");
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startSection(Section, wasm::WASM_SEC_CUSTOM);
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// The position where the section header ends, for measuring its size.
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Section.PayloadOffset = W->OS.tell();
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// Custom sections in wasm also have a string identifier.
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writeString(Name);
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// The position where the custom section starts.
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Section.ContentsOffset = W->OS.tell();
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}
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// Now that the section is complete and we know how big it is, patch up the
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// section size field at the start of the section.
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void WasmObjectWriter::endSection(SectionBookkeeping &Section) {
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uint64_t Size = W->OS.tell();
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// /dev/null doesn't support seek/tell and can report offset of 0.
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// Simply skip this patching in that case.
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if (!Size)
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return;
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Size -= Section.PayloadOffset;
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if (uint32_t(Size) != Size)
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report_fatal_error("section size does not fit in a uint32_t");
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LLVM_DEBUG(dbgs() << "endSection size=" << Size << "\n");
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// Write the final section size to the payload_len field, which follows
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// the section id byte.
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writePatchableLEB<5>(static_cast<raw_pwrite_stream &>(W->OS), Size,
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Section.SizeOffset);
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}
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// Emit the Wasm header.
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void WasmObjectWriter::writeHeader(const MCAssembler &Asm) {
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W->OS.write(wasm::WasmMagic, sizeof(wasm::WasmMagic));
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W->write<uint32_t>(wasm::WasmVersion);
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}
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void WasmObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
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const MCAsmLayout &Layout) {
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// Some compilation units require the indirect function table to be present
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// but don't explicitly reference it. This is the case for call_indirect
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// without the reference-types feature, and also function bitcasts in all
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// cases. In those cases the __indirect_function_table has the
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// WASM_SYMBOL_NO_STRIP attribute. Here we make sure this symbol makes it to
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// the assembler, if needed.
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if (auto *Sym = Asm.getContext().lookupSymbol("__indirect_function_table")) {
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const auto *WasmSym = static_cast<const MCSymbolWasm *>(Sym);
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if (WasmSym->isNoStrip())
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Asm.registerSymbol(*Sym);
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}
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// Build a map of sections to the function that defines them, for use
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// in recordRelocation.
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for (const MCSymbol &S : Asm.symbols()) {
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const auto &WS = static_cast<const MCSymbolWasm &>(S);
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if (WS.isDefined() && WS.isFunction() && !WS.isVariable()) {
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const auto &Sec = static_cast<const MCSectionWasm &>(S.getSection());
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auto Pair = SectionFunctions.insert(std::make_pair(&Sec, &S));
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if (!Pair.second)
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report_fatal_error("section already has a defining function: " +
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Sec.getName());
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}
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}
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}
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void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
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const MCAsmLayout &Layout,
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const MCFragment *Fragment,
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const MCFixup &Fixup, MCValue Target,
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uint64_t &FixedValue) {
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// The WebAssembly backend should never generate FKF_IsPCRel fixups
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assert(!(Asm.getBackend().getFixupKindInfo(Fixup.getKind()).Flags &
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MCFixupKindInfo::FKF_IsPCRel));
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const auto &FixupSection = cast<MCSectionWasm>(*Fragment->getParent());
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uint64_t C = Target.getConstant();
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uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
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MCContext &Ctx = Asm.getContext();
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bool IsLocRel = false;
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if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
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const auto &SymB = cast<MCSymbolWasm>(RefB->getSymbol());
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|
|
if (FixupSection.getKind().isText()) {
|
|
Ctx.reportError(Fixup.getLoc(),
|
|
Twine("symbol '") + SymB.getName() +
|
|
"' unsupported subtraction expression used in "
|
|
"relocation in code section.");
|
|
return;
|
|
}
|
|
|
|
if (SymB.isUndefined()) {
|
|
Ctx.reportError(Fixup.getLoc(),
|
|
Twine("symbol '") + SymB.getName() +
|
|
"' can not be undefined in a subtraction expression");
|
|
return;
|
|
}
|
|
const MCSection &SecB = SymB.getSection();
|
|
if (&SecB != &FixupSection) {
|
|
Ctx.reportError(Fixup.getLoc(),
|
|
Twine("symbol '") + SymB.getName() +
|
|
"' can not be placed in a different section");
|
|
return;
|
|
}
|
|
IsLocRel = true;
|
|
C += FixupOffset - Layout.getSymbolOffset(SymB);
|
|
}
|
|
|
|
// We either rejected the fixup or folded B into C at this point.
|
|
const MCSymbolRefExpr *RefA = Target.getSymA();
|
|
const auto *SymA = cast<MCSymbolWasm>(&RefA->getSymbol());
|
|
|
|
// The .init_array isn't translated as data, so don't do relocations in it.
|
|
if (FixupSection.getName().startswith(".init_array")) {
|
|
SymA->setUsedInInitArray();
|
|
return;
|
|
}
|
|
|
|
if (SymA->isVariable()) {
|
|
const MCExpr *Expr = SymA->getVariableValue();
|
|
if (const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr))
|
|
if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
|
|
llvm_unreachable("weakref used in reloc not yet implemented");
|
|
}
|
|
|
|
// Put any constant offset in an addend. Offsets can be negative, and
|
|
// LLVM expects wrapping, in contrast to wasm's immediates which can't
|
|
// be negative and don't wrap.
|
|
FixedValue = 0;
|
|
|
|
unsigned Type =
|
|
TargetObjectWriter->getRelocType(Target, Fixup, FixupSection, IsLocRel);
|
|
|
|
// Absolute offset within a section or a function.
|
|
// Currently only supported for for metadata sections.
|
|
// See: test/MC/WebAssembly/blockaddress.ll
|
|
if ((Type == wasm::R_WASM_FUNCTION_OFFSET_I32 ||
|
|
Type == wasm::R_WASM_FUNCTION_OFFSET_I64 ||
|
|
Type == wasm::R_WASM_SECTION_OFFSET_I32) &&
|
|
SymA->isDefined()) {
|
|
// SymA can be a temp data symbol that represents a function (in which case
|
|
// it needs to be replaced by the section symbol), [XXX and it apparently
|
|
// later gets changed again to a func symbol?] or it can be a real
|
|
// function symbol, in which case it can be left as-is.
|
|
|
|
if (!FixupSection.getKind().isMetadata())
|
|
report_fatal_error("relocations for function or section offsets are "
|
|
"only supported in metadata sections");
|
|
|
|
const MCSymbol *SectionSymbol = nullptr;
|
|
const MCSection &SecA = SymA->getSection();
|
|
if (SecA.getKind().isText()) {
|
|
auto SecSymIt = SectionFunctions.find(&SecA);
|
|
if (SecSymIt == SectionFunctions.end())
|
|
report_fatal_error("section doesn\'t have defining symbol");
|
|
SectionSymbol = SecSymIt->second;
|
|
} else {
|
|
SectionSymbol = SecA.getBeginSymbol();
|
|
}
|
|
if (!SectionSymbol)
|
|
report_fatal_error("section symbol is required for relocation");
|
|
|
|
C += Layout.getSymbolOffset(*SymA);
|
|
SymA = cast<MCSymbolWasm>(SectionSymbol);
|
|
}
|
|
|
|
if (Type == wasm::R_WASM_TABLE_INDEX_REL_SLEB ||
|
|
Type == wasm::R_WASM_TABLE_INDEX_REL_SLEB64 ||
|
|
Type == wasm::R_WASM_TABLE_INDEX_SLEB ||
|
|
Type == wasm::R_WASM_TABLE_INDEX_SLEB64 ||
|
|
Type == wasm::R_WASM_TABLE_INDEX_I32 ||
|
|
Type == wasm::R_WASM_TABLE_INDEX_I64) {
|
|
// TABLE_INDEX relocs implicitly use the default indirect function table.
|
|
// We require the function table to have already been defined.
|
|
auto TableName = "__indirect_function_table";
|
|
MCSymbolWasm *Sym = cast_or_null<MCSymbolWasm>(Ctx.lookupSymbol(TableName));
|
|
if (!Sym) {
|
|
report_fatal_error("missing indirect function table symbol");
|
|
} else {
|
|
if (!Sym->isFunctionTable())
|
|
report_fatal_error("__indirect_function_table symbol has wrong type");
|
|
// Ensure that __indirect_function_table reaches the output.
|
|
Sym->setNoStrip();
|
|
Asm.registerSymbol(*Sym);
|
|
}
|
|
}
|
|
|
|
// Relocation other than R_WASM_TYPE_INDEX_LEB are required to be
|
|
// against a named symbol.
|
|
if (Type != wasm::R_WASM_TYPE_INDEX_LEB) {
|
|
if (SymA->getName().empty())
|
|
report_fatal_error("relocations against un-named temporaries are not yet "
|
|
"supported by wasm");
|
|
|
|
SymA->setUsedInReloc();
|
|
}
|
|
|
|
if (RefA->getKind() == MCSymbolRefExpr::VK_GOT)
|
|
SymA->setUsedInGOT();
|
|
|
|
WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection);
|
|
LLVM_DEBUG(dbgs() << "WasmReloc: " << Rec << "\n");
|
|
|
|
if (FixupSection.isWasmData()) {
|
|
DataRelocations.push_back(Rec);
|
|
} else if (FixupSection.getKind().isText()) {
|
|
CodeRelocations.push_back(Rec);
|
|
} else if (FixupSection.getKind().isMetadata()) {
|
|
CustomSectionsRelocations[&FixupSection].push_back(Rec);
|
|
} else {
|
|
llvm_unreachable("unexpected section type");
|
|
}
|
|
}
|
|
|
|
// Compute a value to write into the code at the location covered
|
|
// by RelEntry. This value isn't used by the static linker; it just serves
|
|
// to make the object format more readable and more likely to be directly
|
|
// useable.
|
|
uint64_t
|
|
WasmObjectWriter::getProvisionalValue(const WasmRelocationEntry &RelEntry,
|
|
const MCAsmLayout &Layout) {
|
|
if ((RelEntry.Type == wasm::R_WASM_GLOBAL_INDEX_LEB ||
|
|
RelEntry.Type == wasm::R_WASM_GLOBAL_INDEX_I32) &&
|
|
!RelEntry.Symbol->isGlobal()) {
|
|
assert(GOTIndices.count(RelEntry.Symbol) > 0 && "symbol not found in GOT index space");
|
|
return GOTIndices[RelEntry.Symbol];
|
|
}
|
|
|
|
switch (RelEntry.Type) {
|
|
case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
|
|
case wasm::R_WASM_TABLE_INDEX_REL_SLEB64:
|
|
case wasm::R_WASM_TABLE_INDEX_SLEB:
|
|
case wasm::R_WASM_TABLE_INDEX_SLEB64:
|
|
case wasm::R_WASM_TABLE_INDEX_I32:
|
|
case wasm::R_WASM_TABLE_INDEX_I64: {
|
|
// Provisional value is table address of the resolved symbol itself
|
|
const MCSymbolWasm *Base =
|
|
cast<MCSymbolWasm>(Layout.getBaseSymbol(*RelEntry.Symbol));
|
|
assert(Base->isFunction());
|
|
if (RelEntry.Type == wasm::R_WASM_TABLE_INDEX_REL_SLEB ||
|
|
RelEntry.Type == wasm::R_WASM_TABLE_INDEX_REL_SLEB64)
|
|
return TableIndices[Base] - InitialTableOffset;
|
|
else
|
|
return TableIndices[Base];
|
|
}
|
|
case wasm::R_WASM_TYPE_INDEX_LEB:
|
|
// Provisional value is same as the index
|
|
return getRelocationIndexValue(RelEntry);
|
|
case wasm::R_WASM_FUNCTION_INDEX_LEB:
|
|
case wasm::R_WASM_GLOBAL_INDEX_LEB:
|
|
case wasm::R_WASM_GLOBAL_INDEX_I32:
|
|
case wasm::R_WASM_TAG_INDEX_LEB:
|
|
case wasm::R_WASM_TABLE_NUMBER_LEB:
|
|
// Provisional value is function/global/tag Wasm index
|
|
assert(WasmIndices.count(RelEntry.Symbol) > 0 && "symbol not found in wasm index space");
|
|
return WasmIndices[RelEntry.Symbol];
|
|
case wasm::R_WASM_FUNCTION_OFFSET_I32:
|
|
case wasm::R_WASM_FUNCTION_OFFSET_I64:
|
|
case wasm::R_WASM_SECTION_OFFSET_I32: {
|
|
if (!RelEntry.Symbol->isDefined())
|
|
return 0;
|
|
const auto &Section =
|
|
static_cast<const MCSectionWasm &>(RelEntry.Symbol->getSection());
|
|
return Section.getSectionOffset() + RelEntry.Addend;
|
|
}
|
|
case wasm::R_WASM_MEMORY_ADDR_LEB:
|
|
case wasm::R_WASM_MEMORY_ADDR_LEB64:
|
|
case wasm::R_WASM_MEMORY_ADDR_SLEB:
|
|
case wasm::R_WASM_MEMORY_ADDR_SLEB64:
|
|
case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
|
|
case wasm::R_WASM_MEMORY_ADDR_REL_SLEB64:
|
|
case wasm::R_WASM_MEMORY_ADDR_I32:
|
|
case wasm::R_WASM_MEMORY_ADDR_I64:
|
|
case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB:
|
|
case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB64:
|
|
case wasm::R_WASM_MEMORY_ADDR_LOCREL_I32: {
|
|
// Provisional value is address of the global plus the offset
|
|
// For undefined symbols, use zero
|
|
if (!RelEntry.Symbol->isDefined())
|
|
return 0;
|
|
const wasm::WasmDataReference &SymRef = DataLocations[RelEntry.Symbol];
|
|
const WasmDataSegment &Segment = DataSegments[SymRef.Segment];
|
|
// Ignore overflow. LLVM allows address arithmetic to silently wrap.
|
|
return Segment.Offset + SymRef.Offset + RelEntry.Addend;
|
|
}
|
|
default:
|
|
llvm_unreachable("invalid relocation type");
|
|
}
|
|
}
|
|
|
|
static void addData(SmallVectorImpl<char> &DataBytes,
|
|
MCSectionWasm &DataSection) {
|
|
LLVM_DEBUG(errs() << "addData: " << DataSection.getName() << "\n");
|
|
|
|
DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment()));
|
|
|
|
for (const MCFragment &Frag : DataSection) {
|
|
if (Frag.hasInstructions())
|
|
report_fatal_error("only data supported in data sections");
|
|
|
|
if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) {
|
|
if (Align->getValueSize() != 1)
|
|
report_fatal_error("only byte values supported for alignment");
|
|
// If nops are requested, use zeros, as this is the data section.
|
|
uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue();
|
|
uint64_t Size =
|
|
std::min<uint64_t>(alignTo(DataBytes.size(), Align->getAlignment()),
|
|
DataBytes.size() + Align->getMaxBytesToEmit());
|
|
DataBytes.resize(Size, Value);
|
|
} else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) {
|
|
int64_t NumValues;
|
|
if (!Fill->getNumValues().evaluateAsAbsolute(NumValues))
|
|
llvm_unreachable("The fill should be an assembler constant");
|
|
DataBytes.insert(DataBytes.end(), Fill->getValueSize() * NumValues,
|
|
Fill->getValue());
|
|
} else if (auto *LEB = dyn_cast<MCLEBFragment>(&Frag)) {
|
|
const SmallVectorImpl<char> &Contents = LEB->getContents();
|
|
llvm::append_range(DataBytes, Contents);
|
|
} else {
|
|
const auto &DataFrag = cast<MCDataFragment>(Frag);
|
|
const SmallVectorImpl<char> &Contents = DataFrag.getContents();
|
|
llvm::append_range(DataBytes, Contents);
|
|
}
|
|
}
|
|
|
|
LLVM_DEBUG(dbgs() << "addData -> " << DataBytes.size() << "\n");
|
|
}
|
|
|
|
uint32_t
|
|
WasmObjectWriter::getRelocationIndexValue(const WasmRelocationEntry &RelEntry) {
|
|
if (RelEntry.Type == wasm::R_WASM_TYPE_INDEX_LEB) {
|
|
if (!TypeIndices.count(RelEntry.Symbol))
|
|
report_fatal_error("symbol not found in type index space: " +
|
|
RelEntry.Symbol->getName());
|
|
return TypeIndices[RelEntry.Symbol];
|
|
}
|
|
|
|
return RelEntry.Symbol->getIndex();
|
|
}
|
|
|
|
// Apply the portions of the relocation records that we can handle ourselves
|
|
// directly.
|
|
void WasmObjectWriter::applyRelocations(
|
|
ArrayRef<WasmRelocationEntry> Relocations, uint64_t ContentsOffset,
|
|
const MCAsmLayout &Layout) {
|
|
auto &Stream = static_cast<raw_pwrite_stream &>(W->OS);
|
|
for (const WasmRelocationEntry &RelEntry : Relocations) {
|
|
uint64_t Offset = ContentsOffset +
|
|
RelEntry.FixupSection->getSectionOffset() +
|
|
RelEntry.Offset;
|
|
|
|
LLVM_DEBUG(dbgs() << "applyRelocation: " << RelEntry << "\n");
|
|
auto Value = getProvisionalValue(RelEntry, Layout);
|
|
|
|
switch (RelEntry.Type) {
|
|
case wasm::R_WASM_FUNCTION_INDEX_LEB:
|
|
case wasm::R_WASM_TYPE_INDEX_LEB:
|
|
case wasm::R_WASM_GLOBAL_INDEX_LEB:
|
|
case wasm::R_WASM_MEMORY_ADDR_LEB:
|
|
case wasm::R_WASM_TAG_INDEX_LEB:
|
|
case wasm::R_WASM_TABLE_NUMBER_LEB:
|
|
writePatchableLEB<5>(Stream, Value, Offset);
|
|
break;
|
|
case wasm::R_WASM_MEMORY_ADDR_LEB64:
|
|
writePatchableLEB<10>(Stream, Value, Offset);
|
|
break;
|
|
case wasm::R_WASM_TABLE_INDEX_I32:
|
|
case wasm::R_WASM_MEMORY_ADDR_I32:
|
|
case wasm::R_WASM_FUNCTION_OFFSET_I32:
|
|
case wasm::R_WASM_SECTION_OFFSET_I32:
|
|
case wasm::R_WASM_GLOBAL_INDEX_I32:
|
|
case wasm::R_WASM_MEMORY_ADDR_LOCREL_I32:
|
|
patchI32(Stream, Value, Offset);
|
|
break;
|
|
case wasm::R_WASM_TABLE_INDEX_I64:
|
|
case wasm::R_WASM_MEMORY_ADDR_I64:
|
|
case wasm::R_WASM_FUNCTION_OFFSET_I64:
|
|
patchI64(Stream, Value, Offset);
|
|
break;
|
|
case wasm::R_WASM_TABLE_INDEX_SLEB:
|
|
case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
|
|
case wasm::R_WASM_MEMORY_ADDR_SLEB:
|
|
case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
|
|
case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB:
|
|
writePatchableSLEB<5>(Stream, Value, Offset);
|
|
break;
|
|
case wasm::R_WASM_TABLE_INDEX_SLEB64:
|
|
case wasm::R_WASM_TABLE_INDEX_REL_SLEB64:
|
|
case wasm::R_WASM_MEMORY_ADDR_SLEB64:
|
|
case wasm::R_WASM_MEMORY_ADDR_REL_SLEB64:
|
|
case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB64:
|
|
writePatchableSLEB<10>(Stream, Value, Offset);
|
|
break;
|
|
default:
|
|
llvm_unreachable("invalid relocation type");
|
|
}
|
|
}
|
|
}
|
|
|
|
void WasmObjectWriter::writeTypeSection(
|
|
ArrayRef<wasm::WasmSignature> Signatures) {
|
|
if (Signatures.empty())
|
|
return;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_TYPE);
|
|
|
|
encodeULEB128(Signatures.size(), W->OS);
|
|
|
|
for (const wasm::WasmSignature &Sig : Signatures) {
|
|
W->OS << char(wasm::WASM_TYPE_FUNC);
|
|
encodeULEB128(Sig.Params.size(), W->OS);
|
|
for (wasm::ValType Ty : Sig.Params)
|
|
writeValueType(Ty);
|
|
encodeULEB128(Sig.Returns.size(), W->OS);
|
|
for (wasm::ValType Ty : Sig.Returns)
|
|
writeValueType(Ty);
|
|
}
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeImportSection(ArrayRef<wasm::WasmImport> Imports,
|
|
uint64_t DataSize,
|
|
uint32_t NumElements) {
|
|
if (Imports.empty())
|
|
return;
|
|
|
|
uint64_t NumPages = (DataSize + wasm::WasmPageSize - 1) / wasm::WasmPageSize;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_IMPORT);
|
|
|
|
encodeULEB128(Imports.size(), W->OS);
|
|
for (const wasm::WasmImport &Import : Imports) {
|
|
writeString(Import.Module);
|
|
writeString(Import.Field);
|
|
W->OS << char(Import.Kind);
|
|
|
|
switch (Import.Kind) {
|
|
case wasm::WASM_EXTERNAL_FUNCTION:
|
|
encodeULEB128(Import.SigIndex, W->OS);
|
|
break;
|
|
case wasm::WASM_EXTERNAL_GLOBAL:
|
|
W->OS << char(Import.Global.Type);
|
|
W->OS << char(Import.Global.Mutable ? 1 : 0);
|
|
break;
|
|
case wasm::WASM_EXTERNAL_MEMORY:
|
|
encodeULEB128(Import.Memory.Flags, W->OS);
|
|
encodeULEB128(NumPages, W->OS); // initial
|
|
break;
|
|
case wasm::WASM_EXTERNAL_TABLE:
|
|
W->OS << char(Import.Table.ElemType);
|
|
encodeULEB128(0, W->OS); // flags
|
|
encodeULEB128(NumElements, W->OS); // initial
|
|
break;
|
|
case wasm::WASM_EXTERNAL_TAG:
|
|
W->OS << char(Import.Tag.Attribute);
|
|
encodeULEB128(Import.Tag.SigIndex, W->OS);
|
|
break;
|
|
default:
|
|
llvm_unreachable("unsupported import kind");
|
|
}
|
|
}
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeFunctionSection(ArrayRef<WasmFunction> Functions) {
|
|
if (Functions.empty())
|
|
return;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_FUNCTION);
|
|
|
|
encodeULEB128(Functions.size(), W->OS);
|
|
for (const WasmFunction &Func : Functions)
|
|
encodeULEB128(Func.SigIndex, W->OS);
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeTagSection(ArrayRef<wasm::WasmTagType> Tags) {
|
|
if (Tags.empty())
|
|
return;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_TAG);
|
|
|
|
encodeULEB128(Tags.size(), W->OS);
|
|
for (const wasm::WasmTagType &Tag : Tags) {
|
|
W->OS << char(Tag.Attribute);
|
|
encodeULEB128(Tag.SigIndex, W->OS);
|
|
}
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeGlobalSection(ArrayRef<wasm::WasmGlobal> Globals) {
|
|
if (Globals.empty())
|
|
return;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_GLOBAL);
|
|
|
|
encodeULEB128(Globals.size(), W->OS);
|
|
for (const wasm::WasmGlobal &Global : Globals) {
|
|
encodeULEB128(Global.Type.Type, W->OS);
|
|
W->OS << char(Global.Type.Mutable);
|
|
W->OS << char(Global.InitExpr.Opcode);
|
|
switch (Global.Type.Type) {
|
|
case wasm::WASM_TYPE_I32:
|
|
encodeSLEB128(0, W->OS);
|
|
break;
|
|
case wasm::WASM_TYPE_I64:
|
|
encodeSLEB128(0, W->OS);
|
|
break;
|
|
case wasm::WASM_TYPE_F32:
|
|
writeI32(0);
|
|
break;
|
|
case wasm::WASM_TYPE_F64:
|
|
writeI64(0);
|
|
break;
|
|
case wasm::WASM_TYPE_EXTERNREF:
|
|
writeValueType(wasm::ValType::EXTERNREF);
|
|
break;
|
|
default:
|
|
llvm_unreachable("unexpected type");
|
|
}
|
|
W->OS << char(wasm::WASM_OPCODE_END);
|
|
}
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeTableSection(ArrayRef<wasm::WasmTable> Tables) {
|
|
if (Tables.empty())
|
|
return;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_TABLE);
|
|
|
|
encodeULEB128(Tables.size(), W->OS);
|
|
for (const wasm::WasmTable &Table : Tables) {
|
|
encodeULEB128(Table.Type.ElemType, W->OS);
|
|
encodeULEB128(Table.Type.Limits.Flags, W->OS);
|
|
encodeULEB128(Table.Type.Limits.Minimum, W->OS);
|
|
if (Table.Type.Limits.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX)
|
|
encodeULEB128(Table.Type.Limits.Maximum, W->OS);
|
|
}
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeExportSection(ArrayRef<wasm::WasmExport> Exports) {
|
|
if (Exports.empty())
|
|
return;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_EXPORT);
|
|
|
|
encodeULEB128(Exports.size(), W->OS);
|
|
for (const wasm::WasmExport &Export : Exports) {
|
|
writeString(Export.Name);
|
|
W->OS << char(Export.Kind);
|
|
encodeULEB128(Export.Index, W->OS);
|
|
}
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeElemSection(
|
|
const MCSymbolWasm *IndirectFunctionTable, ArrayRef<uint32_t> TableElems) {
|
|
if (TableElems.empty())
|
|
return;
|
|
|
|
assert(IndirectFunctionTable);
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_ELEM);
|
|
|
|
encodeULEB128(1, W->OS); // number of "segments"
|
|
|
|
assert(WasmIndices.count(IndirectFunctionTable));
|
|
uint32_t TableNumber = WasmIndices.find(IndirectFunctionTable)->second;
|
|
uint32_t Flags = 0;
|
|
if (TableNumber)
|
|
Flags |= wasm::WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER;
|
|
encodeULEB128(Flags, W->OS);
|
|
if (Flags & wasm::WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER)
|
|
encodeULEB128(TableNumber, W->OS); // the table number
|
|
|
|
// init expr for starting offset
|
|
W->OS << char(wasm::WASM_OPCODE_I32_CONST);
|
|
encodeSLEB128(InitialTableOffset, W->OS);
|
|
W->OS << char(wasm::WASM_OPCODE_END);
|
|
|
|
if (Flags & wasm::WASM_ELEM_SEGMENT_MASK_HAS_ELEM_KIND) {
|
|
// We only write active function table initializers, for which the elem kind
|
|
// is specified to be written as 0x00 and interpreted to mean "funcref".
|
|
const uint8_t ElemKind = 0;
|
|
W->OS << ElemKind;
|
|
}
|
|
|
|
encodeULEB128(TableElems.size(), W->OS);
|
|
for (uint32_t Elem : TableElems)
|
|
encodeULEB128(Elem, W->OS);
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeDataCountSection() {
|
|
if (DataSegments.empty())
|
|
return;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_DATACOUNT);
|
|
encodeULEB128(DataSegments.size(), W->OS);
|
|
endSection(Section);
|
|
}
|
|
|
|
uint32_t WasmObjectWriter::writeCodeSection(const MCAssembler &Asm,
|
|
const MCAsmLayout &Layout,
|
|
ArrayRef<WasmFunction> Functions) {
|
|
if (Functions.empty())
|
|
return 0;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_CODE);
|
|
|
|
encodeULEB128(Functions.size(), W->OS);
|
|
|
|
for (const WasmFunction &Func : Functions) {
|
|
auto &FuncSection = static_cast<MCSectionWasm &>(Func.Sym->getSection());
|
|
|
|
int64_t Size = 0;
|
|
if (!Func.Sym->getSize()->evaluateAsAbsolute(Size, Layout))
|
|
report_fatal_error(".size expression must be evaluatable");
|
|
|
|
encodeULEB128(Size, W->OS);
|
|
FuncSection.setSectionOffset(W->OS.tell() - Section.ContentsOffset);
|
|
Asm.writeSectionData(W->OS, &FuncSection, Layout);
|
|
}
|
|
|
|
// Apply fixups.
|
|
applyRelocations(CodeRelocations, Section.ContentsOffset, Layout);
|
|
|
|
endSection(Section);
|
|
return Section.Index;
|
|
}
|
|
|
|
uint32_t WasmObjectWriter::writeDataSection(const MCAsmLayout &Layout) {
|
|
if (DataSegments.empty())
|
|
return 0;
|
|
|
|
SectionBookkeeping Section;
|
|
startSection(Section, wasm::WASM_SEC_DATA);
|
|
|
|
encodeULEB128(DataSegments.size(), W->OS); // count
|
|
|
|
for (const WasmDataSegment &Segment : DataSegments) {
|
|
encodeULEB128(Segment.InitFlags, W->OS); // flags
|
|
if (Segment.InitFlags & wasm::WASM_DATA_SEGMENT_HAS_MEMINDEX)
|
|
encodeULEB128(0, W->OS); // memory index
|
|
if ((Segment.InitFlags & wasm::WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
|
|
W->OS << char(is64Bit() ? wasm::WASM_OPCODE_I64_CONST
|
|
: wasm::WASM_OPCODE_I32_CONST);
|
|
encodeSLEB128(Segment.Offset, W->OS); // offset
|
|
W->OS << char(wasm::WASM_OPCODE_END);
|
|
}
|
|
encodeULEB128(Segment.Data.size(), W->OS); // size
|
|
Segment.Section->setSectionOffset(W->OS.tell() - Section.ContentsOffset);
|
|
W->OS << Segment.Data; // data
|
|
}
|
|
|
|
// Apply fixups.
|
|
applyRelocations(DataRelocations, Section.ContentsOffset, Layout);
|
|
|
|
endSection(Section);
|
|
return Section.Index;
|
|
}
|
|
|
|
void WasmObjectWriter::writeRelocSection(
|
|
uint32_t SectionIndex, StringRef Name,
|
|
std::vector<WasmRelocationEntry> &Relocs) {
|
|
// See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md
|
|
// for descriptions of the reloc sections.
|
|
|
|
if (Relocs.empty())
|
|
return;
|
|
|
|
// First, ensure the relocations are sorted in offset order. In general they
|
|
// should already be sorted since `recordRelocation` is called in offset
|
|
// order, but for the code section we combine many MC sections into single
|
|
// wasm section, and this order is determined by the order of Asm.Symbols()
|
|
// not the sections order.
|
|
llvm::stable_sort(
|
|
Relocs, [](const WasmRelocationEntry &A, const WasmRelocationEntry &B) {
|
|
return (A.Offset + A.FixupSection->getSectionOffset()) <
|
|
(B.Offset + B.FixupSection->getSectionOffset());
|
|
});
|
|
|
|
SectionBookkeeping Section;
|
|
startCustomSection(Section, std::string("reloc.") + Name.str());
|
|
|
|
encodeULEB128(SectionIndex, W->OS);
|
|
encodeULEB128(Relocs.size(), W->OS);
|
|
for (const WasmRelocationEntry &RelEntry : Relocs) {
|
|
uint64_t Offset =
|
|
RelEntry.Offset + RelEntry.FixupSection->getSectionOffset();
|
|
uint32_t Index = getRelocationIndexValue(RelEntry);
|
|
|
|
W->OS << char(RelEntry.Type);
|
|
encodeULEB128(Offset, W->OS);
|
|
encodeULEB128(Index, W->OS);
|
|
if (RelEntry.hasAddend())
|
|
encodeSLEB128(RelEntry.Addend, W->OS);
|
|
}
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeCustomRelocSections() {
|
|
for (const auto &Sec : CustomSections) {
|
|
auto &Relocations = CustomSectionsRelocations[Sec.Section];
|
|
writeRelocSection(Sec.OutputIndex, Sec.Name, Relocations);
|
|
}
|
|
}
|
|
|
|
void WasmObjectWriter::writeLinkingMetaDataSection(
|
|
ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
|
|
ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs,
|
|
const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats) {
|
|
SectionBookkeeping Section;
|
|
startCustomSection(Section, "linking");
|
|
encodeULEB128(wasm::WasmMetadataVersion, W->OS);
|
|
|
|
SectionBookkeeping SubSection;
|
|
if (SymbolInfos.size() != 0) {
|
|
startSection(SubSection, wasm::WASM_SYMBOL_TABLE);
|
|
encodeULEB128(SymbolInfos.size(), W->OS);
|
|
for (const wasm::WasmSymbolInfo &Sym : SymbolInfos) {
|
|
encodeULEB128(Sym.Kind, W->OS);
|
|
encodeULEB128(Sym.Flags, W->OS);
|
|
switch (Sym.Kind) {
|
|
case wasm::WASM_SYMBOL_TYPE_FUNCTION:
|
|
case wasm::WASM_SYMBOL_TYPE_GLOBAL:
|
|
case wasm::WASM_SYMBOL_TYPE_TAG:
|
|
case wasm::WASM_SYMBOL_TYPE_TABLE:
|
|
encodeULEB128(Sym.ElementIndex, W->OS);
|
|
if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0 ||
|
|
(Sym.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
|
|
writeString(Sym.Name);
|
|
break;
|
|
case wasm::WASM_SYMBOL_TYPE_DATA:
|
|
writeString(Sym.Name);
|
|
if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0) {
|
|
encodeULEB128(Sym.DataRef.Segment, W->OS);
|
|
encodeULEB128(Sym.DataRef.Offset, W->OS);
|
|
encodeULEB128(Sym.DataRef.Size, W->OS);
|
|
}
|
|
break;
|
|
case wasm::WASM_SYMBOL_TYPE_SECTION: {
|
|
const uint32_t SectionIndex =
|
|
CustomSections[Sym.ElementIndex].OutputIndex;
|
|
encodeULEB128(SectionIndex, W->OS);
|
|
break;
|
|
}
|
|
default:
|
|
llvm_unreachable("unexpected kind");
|
|
}
|
|
}
|
|
endSection(SubSection);
|
|
}
|
|
|
|
if (DataSegments.size()) {
|
|
startSection(SubSection, wasm::WASM_SEGMENT_INFO);
|
|
encodeULEB128(DataSegments.size(), W->OS);
|
|
for (const WasmDataSegment &Segment : DataSegments) {
|
|
writeString(Segment.Name);
|
|
encodeULEB128(Segment.Alignment, W->OS);
|
|
encodeULEB128(Segment.LinkingFlags, W->OS);
|
|
}
|
|
endSection(SubSection);
|
|
}
|
|
|
|
if (!InitFuncs.empty()) {
|
|
startSection(SubSection, wasm::WASM_INIT_FUNCS);
|
|
encodeULEB128(InitFuncs.size(), W->OS);
|
|
for (auto &StartFunc : InitFuncs) {
|
|
encodeULEB128(StartFunc.first, W->OS); // priority
|
|
encodeULEB128(StartFunc.second, W->OS); // function index
|
|
}
|
|
endSection(SubSection);
|
|
}
|
|
|
|
if (Comdats.size()) {
|
|
startSection(SubSection, wasm::WASM_COMDAT_INFO);
|
|
encodeULEB128(Comdats.size(), W->OS);
|
|
for (const auto &C : Comdats) {
|
|
writeString(C.first);
|
|
encodeULEB128(0, W->OS); // flags for future use
|
|
encodeULEB128(C.second.size(), W->OS);
|
|
for (const WasmComdatEntry &Entry : C.second) {
|
|
encodeULEB128(Entry.Kind, W->OS);
|
|
encodeULEB128(Entry.Index, W->OS);
|
|
}
|
|
}
|
|
endSection(SubSection);
|
|
}
|
|
|
|
endSection(Section);
|
|
}
|
|
|
|
void WasmObjectWriter::writeCustomSection(WasmCustomSection &CustomSection,
|
|
const MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
SectionBookkeeping Section;
|
|
auto *Sec = CustomSection.Section;
|
|
startCustomSection(Section, CustomSection.Name);
|
|
|
|
Sec->setSectionOffset(W->OS.tell() - Section.ContentsOffset);
|
|
Asm.writeSectionData(W->OS, Sec, Layout);
|
|
|
|
CustomSection.OutputContentsOffset = Section.ContentsOffset;
|
|
CustomSection.OutputIndex = Section.Index;
|
|
|
|
endSection(Section);
|
|
|
|
// Apply fixups.
|
|
auto &Relocations = CustomSectionsRelocations[CustomSection.Section];
|
|
applyRelocations(Relocations, CustomSection.OutputContentsOffset, Layout);
|
|
}
|
|
|
|
uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm &Symbol) {
|
|
assert(Symbol.isFunction());
|
|
assert(TypeIndices.count(&Symbol));
|
|
return TypeIndices[&Symbol];
|
|
}
|
|
|
|
uint32_t WasmObjectWriter::getTagType(const MCSymbolWasm &Symbol) {
|
|
assert(Symbol.isTag());
|
|
assert(TypeIndices.count(&Symbol));
|
|
return TypeIndices[&Symbol];
|
|
}
|
|
|
|
void WasmObjectWriter::registerFunctionType(const MCSymbolWasm &Symbol) {
|
|
assert(Symbol.isFunction());
|
|
|
|
wasm::WasmSignature S;
|
|
|
|
if (auto *Sig = Symbol.getSignature()) {
|
|
S.Returns = Sig->Returns;
|
|
S.Params = Sig->Params;
|
|
}
|
|
|
|
auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size()));
|
|
if (Pair.second)
|
|
Signatures.push_back(S);
|
|
TypeIndices[&Symbol] = Pair.first->second;
|
|
|
|
LLVM_DEBUG(dbgs() << "registerFunctionType: " << Symbol
|
|
<< " new:" << Pair.second << "\n");
|
|
LLVM_DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n");
|
|
}
|
|
|
|
void WasmObjectWriter::registerTagType(const MCSymbolWasm &Symbol) {
|
|
assert(Symbol.isTag());
|
|
|
|
// TODO Currently we don't generate imported exceptions, but if we do, we
|
|
// should have a way of infering types of imported exceptions.
|
|
wasm::WasmSignature S;
|
|
if (auto *Sig = Symbol.getSignature()) {
|
|
S.Returns = Sig->Returns;
|
|
S.Params = Sig->Params;
|
|
}
|
|
|
|
auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size()));
|
|
if (Pair.second)
|
|
Signatures.push_back(S);
|
|
TypeIndices[&Symbol] = Pair.first->second;
|
|
|
|
LLVM_DEBUG(dbgs() << "registerTagType: " << Symbol << " new:" << Pair.second
|
|
<< "\n");
|
|
LLVM_DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n");
|
|
}
|
|
|
|
static bool isInSymtab(const MCSymbolWasm &Sym) {
|
|
if (Sym.isUsedInReloc() || Sym.isUsedInInitArray())
|
|
return true;
|
|
|
|
if (Sym.isComdat() && !Sym.isDefined())
|
|
return false;
|
|
|
|
if (Sym.isTemporary())
|
|
return false;
|
|
|
|
if (Sym.isSection())
|
|
return false;
|
|
|
|
if (Sym.omitFromLinkingSection())
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
void WasmObjectWriter::prepareImports(
|
|
SmallVectorImpl<wasm::WasmImport> &Imports, MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
// For now, always emit the memory import, since loads and stores are not
|
|
// valid without it. In the future, we could perhaps be more clever and omit
|
|
// it if there are no loads or stores.
|
|
wasm::WasmImport MemImport;
|
|
MemImport.Module = "env";
|
|
MemImport.Field = "__linear_memory";
|
|
MemImport.Kind = wasm::WASM_EXTERNAL_MEMORY;
|
|
MemImport.Memory.Flags = is64Bit() ? wasm::WASM_LIMITS_FLAG_IS_64
|
|
: wasm::WASM_LIMITS_FLAG_NONE;
|
|
Imports.push_back(MemImport);
|
|
|
|
// Populate SignatureIndices, and Imports and WasmIndices for undefined
|
|
// symbols. This must be done before populating WasmIndices for defined
|
|
// symbols.
|
|
for (const MCSymbol &S : Asm.symbols()) {
|
|
const auto &WS = static_cast<const MCSymbolWasm &>(S);
|
|
|
|
// Register types for all functions, including those with private linkage
|
|
// (because wasm always needs a type signature).
|
|
if (WS.isFunction()) {
|
|
const auto *BS = Layout.getBaseSymbol(S);
|
|
if (!BS)
|
|
report_fatal_error(Twine(S.getName()) +
|
|
": absolute addressing not supported!");
|
|
registerFunctionType(*cast<MCSymbolWasm>(BS));
|
|
}
|
|
|
|
if (WS.isTag())
|
|
registerTagType(WS);
|
|
|
|
if (WS.isTemporary())
|
|
continue;
|
|
|
|
// If the symbol is not defined in this translation unit, import it.
|
|
if (!WS.isDefined() && !WS.isComdat()) {
|
|
if (WS.isFunction()) {
|
|
wasm::WasmImport Import;
|
|
Import.Module = WS.getImportModule();
|
|
Import.Field = WS.getImportName();
|
|
Import.Kind = wasm::WASM_EXTERNAL_FUNCTION;
|
|
Import.SigIndex = getFunctionType(WS);
|
|
Imports.push_back(Import);
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = NumFunctionImports++;
|
|
} else if (WS.isGlobal()) {
|
|
if (WS.isWeak())
|
|
report_fatal_error("undefined global symbol cannot be weak");
|
|
|
|
wasm::WasmImport Import;
|
|
Import.Field = WS.getImportName();
|
|
Import.Kind = wasm::WASM_EXTERNAL_GLOBAL;
|
|
Import.Module = WS.getImportModule();
|
|
Import.Global = WS.getGlobalType();
|
|
Imports.push_back(Import);
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = NumGlobalImports++;
|
|
} else if (WS.isTag()) {
|
|
if (WS.isWeak())
|
|
report_fatal_error("undefined tag symbol cannot be weak");
|
|
|
|
wasm::WasmImport Import;
|
|
Import.Module = WS.getImportModule();
|
|
Import.Field = WS.getImportName();
|
|
Import.Kind = wasm::WASM_EXTERNAL_TAG;
|
|
Import.Tag.Attribute = wasm::WASM_TAG_ATTRIBUTE_EXCEPTION;
|
|
Import.Tag.SigIndex = getTagType(WS);
|
|
Imports.push_back(Import);
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = NumTagImports++;
|
|
} else if (WS.isTable()) {
|
|
if (WS.isWeak())
|
|
report_fatal_error("undefined table symbol cannot be weak");
|
|
|
|
wasm::WasmImport Import;
|
|
Import.Module = WS.getImportModule();
|
|
Import.Field = WS.getImportName();
|
|
Import.Kind = wasm::WASM_EXTERNAL_TABLE;
|
|
Import.Table = WS.getTableType();
|
|
Imports.push_back(Import);
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = NumTableImports++;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Add imports for GOT globals
|
|
for (const MCSymbol &S : Asm.symbols()) {
|
|
const auto &WS = static_cast<const MCSymbolWasm &>(S);
|
|
if (WS.isUsedInGOT()) {
|
|
wasm::WasmImport Import;
|
|
if (WS.isFunction())
|
|
Import.Module = "GOT.func";
|
|
else
|
|
Import.Module = "GOT.mem";
|
|
Import.Field = WS.getName();
|
|
Import.Kind = wasm::WASM_EXTERNAL_GLOBAL;
|
|
Import.Global = {wasm::WASM_TYPE_I32, true};
|
|
Imports.push_back(Import);
|
|
assert(GOTIndices.count(&WS) == 0);
|
|
GOTIndices[&WS] = NumGlobalImports++;
|
|
}
|
|
}
|
|
}
|
|
|
|
uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout) {
|
|
support::endian::Writer MainWriter(*OS, support::little);
|
|
W = &MainWriter;
|
|
if (IsSplitDwarf) {
|
|
uint64_t TotalSize = writeOneObject(Asm, Layout, DwoMode::NonDwoOnly);
|
|
assert(DwoOS);
|
|
support::endian::Writer DwoWriter(*DwoOS, support::little);
|
|
W = &DwoWriter;
|
|
return TotalSize + writeOneObject(Asm, Layout, DwoMode::DwoOnly);
|
|
} else {
|
|
return writeOneObject(Asm, Layout, DwoMode::AllSections);
|
|
}
|
|
}
|
|
|
|
uint64_t WasmObjectWriter::writeOneObject(MCAssembler &Asm,
|
|
const MCAsmLayout &Layout,
|
|
DwoMode Mode) {
|
|
uint64_t StartOffset = W->OS.tell();
|
|
SectionCount = 0;
|
|
CustomSections.clear();
|
|
|
|
LLVM_DEBUG(dbgs() << "WasmObjectWriter::writeObject\n");
|
|
|
|
// Collect information from the available symbols.
|
|
SmallVector<WasmFunction, 4> Functions;
|
|
SmallVector<uint32_t, 4> TableElems;
|
|
SmallVector<wasm::WasmImport, 4> Imports;
|
|
SmallVector<wasm::WasmExport, 4> Exports;
|
|
SmallVector<wasm::WasmTagType, 1> Tags;
|
|
SmallVector<wasm::WasmGlobal, 1> Globals;
|
|
SmallVector<wasm::WasmTable, 1> Tables;
|
|
SmallVector<wasm::WasmSymbolInfo, 4> SymbolInfos;
|
|
SmallVector<std::pair<uint16_t, uint32_t>, 2> InitFuncs;
|
|
std::map<StringRef, std::vector<WasmComdatEntry>> Comdats;
|
|
uint64_t DataSize = 0;
|
|
if (Mode != DwoMode::DwoOnly) {
|
|
prepareImports(Imports, Asm, Layout);
|
|
}
|
|
|
|
// Populate DataSegments and CustomSections, which must be done before
|
|
// populating DataLocations.
|
|
for (MCSection &Sec : Asm) {
|
|
auto &Section = static_cast<MCSectionWasm &>(Sec);
|
|
StringRef SectionName = Section.getName();
|
|
|
|
if (Mode == DwoMode::NonDwoOnly && isDwoSection(Sec))
|
|
continue;
|
|
if (Mode == DwoMode::DwoOnly && !isDwoSection(Sec))
|
|
continue;
|
|
|
|
LLVM_DEBUG(dbgs() << "Processing Section " << SectionName << " group "
|
|
<< Section.getGroup() << "\n";);
|
|
|
|
// .init_array sections are handled specially elsewhere.
|
|
if (SectionName.startswith(".init_array"))
|
|
continue;
|
|
|
|
// Code is handled separately
|
|
if (Section.getKind().isText())
|
|
continue;
|
|
|
|
if (Section.isWasmData()) {
|
|
uint32_t SegmentIndex = DataSegments.size();
|
|
DataSize = alignTo(DataSize, Section.getAlignment());
|
|
DataSegments.emplace_back();
|
|
WasmDataSegment &Segment = DataSegments.back();
|
|
Segment.Name = SectionName;
|
|
Segment.InitFlags = Section.getPassive()
|
|
? (uint32_t)wasm::WASM_DATA_SEGMENT_IS_PASSIVE
|
|
: 0;
|
|
Segment.Offset = DataSize;
|
|
Segment.Section = &Section;
|
|
addData(Segment.Data, Section);
|
|
Segment.Alignment = Log2_32(Section.getAlignment());
|
|
Segment.LinkingFlags = Section.getSegmentFlags();
|
|
DataSize += Segment.Data.size();
|
|
Section.setSegmentIndex(SegmentIndex);
|
|
|
|
if (const MCSymbolWasm *C = Section.getGroup()) {
|
|
Comdats[C->getName()].emplace_back(
|
|
WasmComdatEntry{wasm::WASM_COMDAT_DATA, SegmentIndex});
|
|
}
|
|
} else {
|
|
// Create custom sections
|
|
assert(Sec.getKind().isMetadata());
|
|
|
|
StringRef Name = SectionName;
|
|
|
|
// For user-defined custom sections, strip the prefix
|
|
if (Name.startswith(".custom_section."))
|
|
Name = Name.substr(strlen(".custom_section."));
|
|
|
|
MCSymbol *Begin = Sec.getBeginSymbol();
|
|
if (Begin) {
|
|
assert(WasmIndices.count(cast<MCSymbolWasm>(Begin)) == 0);
|
|
WasmIndices[cast<MCSymbolWasm>(Begin)] = CustomSections.size();
|
|
}
|
|
|
|
// Separate out the producers and target features sections
|
|
if (Name == "producers") {
|
|
ProducersSection = std::make_unique<WasmCustomSection>(Name, &Section);
|
|
continue;
|
|
}
|
|
if (Name == "target_features") {
|
|
TargetFeaturesSection =
|
|
std::make_unique<WasmCustomSection>(Name, &Section);
|
|
continue;
|
|
}
|
|
|
|
// Custom sections can also belong to COMDAT groups. In this case the
|
|
// decriptor's "index" field is the section index (in the final object
|
|
// file), but that is not known until after layout, so it must be fixed up
|
|
// later
|
|
if (const MCSymbolWasm *C = Section.getGroup()) {
|
|
Comdats[C->getName()].emplace_back(
|
|
WasmComdatEntry{wasm::WASM_COMDAT_SECTION,
|
|
static_cast<uint32_t>(CustomSections.size())});
|
|
}
|
|
|
|
CustomSections.emplace_back(Name, &Section);
|
|
}
|
|
}
|
|
|
|
if (Mode != DwoMode::DwoOnly) {
|
|
// Populate WasmIndices and DataLocations for defined symbols.
|
|
for (const MCSymbol &S : Asm.symbols()) {
|
|
// Ignore unnamed temporary symbols, which aren't ever exported, imported,
|
|
// or used in relocations.
|
|
if (S.isTemporary() && S.getName().empty())
|
|
continue;
|
|
|
|
const auto &WS = static_cast<const MCSymbolWasm &>(S);
|
|
LLVM_DEBUG(dbgs()
|
|
<< "MCSymbol: "
|
|
<< toString(WS.getType().getValueOr(wasm::WASM_SYMBOL_TYPE_DATA))
|
|
<< " '" << S << "'"
|
|
<< " isDefined=" << S.isDefined() << " isExternal="
|
|
<< S.isExternal() << " isTemporary=" << S.isTemporary()
|
|
<< " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden()
|
|
<< " isVariable=" << WS.isVariable() << "\n");
|
|
|
|
if (WS.isVariable())
|
|
continue;
|
|
if (WS.isComdat() && !WS.isDefined())
|
|
continue;
|
|
|
|
if (WS.isFunction()) {
|
|
unsigned Index;
|
|
if (WS.isDefined()) {
|
|
if (WS.getOffset() != 0)
|
|
report_fatal_error(
|
|
"function sections must contain one function each");
|
|
|
|
if (WS.getSize() == nullptr)
|
|
report_fatal_error(
|
|
"function symbols must have a size set with .size");
|
|
|
|
// A definition. Write out the function body.
|
|
Index = NumFunctionImports + Functions.size();
|
|
WasmFunction Func;
|
|
Func.SigIndex = getFunctionType(WS);
|
|
Func.Sym = &WS;
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = Index;
|
|
Functions.push_back(Func);
|
|
|
|
auto &Section = static_cast<MCSectionWasm &>(WS.getSection());
|
|
if (const MCSymbolWasm *C = Section.getGroup()) {
|
|
Comdats[C->getName()].emplace_back(
|
|
WasmComdatEntry{wasm::WASM_COMDAT_FUNCTION, Index});
|
|
}
|
|
|
|
if (WS.hasExportName()) {
|
|
wasm::WasmExport Export;
|
|
Export.Name = WS.getExportName();
|
|
Export.Kind = wasm::WASM_EXTERNAL_FUNCTION;
|
|
Export.Index = Index;
|
|
Exports.push_back(Export);
|
|
}
|
|
} else {
|
|
// An import; the index was assigned above.
|
|
Index = WasmIndices.find(&WS)->second;
|
|
}
|
|
|
|
LLVM_DEBUG(dbgs() << " -> function index: " << Index << "\n");
|
|
|
|
} else if (WS.isData()) {
|
|
if (!isInSymtab(WS))
|
|
continue;
|
|
|
|
if (!WS.isDefined()) {
|
|
LLVM_DEBUG(dbgs() << " -> segment index: -1"
|
|
<< "\n");
|
|
continue;
|
|
}
|
|
|
|
if (!WS.getSize())
|
|
report_fatal_error("data symbols must have a size set with .size: " +
|
|
WS.getName());
|
|
|
|
int64_t Size = 0;
|
|
if (!WS.getSize()->evaluateAsAbsolute(Size, Layout))
|
|
report_fatal_error(".size expression must be evaluatable");
|
|
|
|
auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection());
|
|
if (!DataSection.isWasmData())
|
|
report_fatal_error("data symbols must live in a data section: " +
|
|
WS.getName());
|
|
|
|
// For each data symbol, export it in the symtab as a reference to the
|
|
// corresponding Wasm data segment.
|
|
wasm::WasmDataReference Ref = wasm::WasmDataReference{
|
|
DataSection.getSegmentIndex(), Layout.getSymbolOffset(WS),
|
|
static_cast<uint64_t>(Size)};
|
|
assert(DataLocations.count(&WS) == 0);
|
|
DataLocations[&WS] = Ref;
|
|
LLVM_DEBUG(dbgs() << " -> segment index: " << Ref.Segment << "\n");
|
|
|
|
} else if (WS.isGlobal()) {
|
|
// A "true" Wasm global (currently just __stack_pointer)
|
|
if (WS.isDefined()) {
|
|
wasm::WasmGlobal Global;
|
|
Global.Type = WS.getGlobalType();
|
|
Global.Index = NumGlobalImports + Globals.size();
|
|
switch (Global.Type.Type) {
|
|
case wasm::WASM_TYPE_I32:
|
|
Global.InitExpr.Opcode = wasm::WASM_OPCODE_I32_CONST;
|
|
break;
|
|
case wasm::WASM_TYPE_I64:
|
|
Global.InitExpr.Opcode = wasm::WASM_OPCODE_I64_CONST;
|
|
break;
|
|
case wasm::WASM_TYPE_F32:
|
|
Global.InitExpr.Opcode = wasm::WASM_OPCODE_F32_CONST;
|
|
break;
|
|
case wasm::WASM_TYPE_F64:
|
|
Global.InitExpr.Opcode = wasm::WASM_OPCODE_F64_CONST;
|
|
break;
|
|
case wasm::WASM_TYPE_EXTERNREF:
|
|
Global.InitExpr.Opcode = wasm::WASM_OPCODE_REF_NULL;
|
|
break;
|
|
default:
|
|
llvm_unreachable("unexpected type");
|
|
}
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = Global.Index;
|
|
Globals.push_back(Global);
|
|
} else {
|
|
// An import; the index was assigned above
|
|
LLVM_DEBUG(dbgs() << " -> global index: "
|
|
<< WasmIndices.find(&WS)->second << "\n");
|
|
}
|
|
} else if (WS.isTable()) {
|
|
if (WS.isDefined()) {
|
|
wasm::WasmTable Table;
|
|
Table.Index = NumTableImports + Tables.size();
|
|
Table.Type = WS.getTableType();
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = Table.Index;
|
|
Tables.push_back(Table);
|
|
}
|
|
LLVM_DEBUG(dbgs() << " -> table index: "
|
|
<< WasmIndices.find(&WS)->second << "\n");
|
|
} else if (WS.isTag()) {
|
|
// C++ exception symbol (__cpp_exception)
|
|
unsigned Index;
|
|
if (WS.isDefined()) {
|
|
Index = NumTagImports + Tags.size();
|
|
wasm::WasmTagType Tag;
|
|
Tag.SigIndex = getTagType(WS);
|
|
Tag.Attribute = wasm::WASM_TAG_ATTRIBUTE_EXCEPTION;
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = Index;
|
|
Tags.push_back(Tag);
|
|
} else {
|
|
// An import; the index was assigned above.
|
|
assert(WasmIndices.count(&WS) > 0);
|
|
}
|
|
LLVM_DEBUG(dbgs() << " -> tag index: " << WasmIndices.find(&WS)->second
|
|
<< "\n");
|
|
|
|
} else {
|
|
assert(WS.isSection());
|
|
}
|
|
}
|
|
|
|
// Populate WasmIndices and DataLocations for aliased symbols. We need to
|
|
// process these in a separate pass because we need to have processed the
|
|
// target of the alias before the alias itself and the symbols are not
|
|
// necessarily ordered in this way.
|
|
for (const MCSymbol &S : Asm.symbols()) {
|
|
if (!S.isVariable())
|
|
continue;
|
|
|
|
assert(S.isDefined());
|
|
|
|
const auto *BS = Layout.getBaseSymbol(S);
|
|
if (!BS)
|
|
report_fatal_error(Twine(S.getName()) +
|
|
": absolute addressing not supported!");
|
|
const MCSymbolWasm *Base = cast<MCSymbolWasm>(BS);
|
|
|
|
// Find the target symbol of this weak alias and export that index
|
|
const auto &WS = static_cast<const MCSymbolWasm &>(S);
|
|
LLVM_DEBUG(dbgs() << WS.getName() << ": weak alias of '" << *Base
|
|
<< "'\n");
|
|
|
|
if (Base->isFunction()) {
|
|
assert(WasmIndices.count(Base) > 0);
|
|
uint32_t WasmIndex = WasmIndices.find(Base)->second;
|
|
assert(WasmIndices.count(&WS) == 0);
|
|
WasmIndices[&WS] = WasmIndex;
|
|
LLVM_DEBUG(dbgs() << " -> index:" << WasmIndex << "\n");
|
|
} else if (Base->isData()) {
|
|
auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection());
|
|
uint64_t Offset = Layout.getSymbolOffset(S);
|
|
int64_t Size = 0;
|
|
// For data symbol alias we use the size of the base symbol as the
|
|
// size of the alias. When an offset from the base is involved this
|
|
// can result in a offset + size goes past the end of the data section
|
|
// which out object format doesn't support. So we must clamp it.
|
|
if (!Base->getSize()->evaluateAsAbsolute(Size, Layout))
|
|
report_fatal_error(".size expression must be evaluatable");
|
|
const WasmDataSegment &Segment =
|
|
DataSegments[DataSection.getSegmentIndex()];
|
|
Size =
|
|
std::min(static_cast<uint64_t>(Size), Segment.Data.size() - Offset);
|
|
wasm::WasmDataReference Ref = wasm::WasmDataReference{
|
|
DataSection.getSegmentIndex(),
|
|
static_cast<uint32_t>(Layout.getSymbolOffset(S)),
|
|
static_cast<uint32_t>(Size)};
|
|
DataLocations[&WS] = Ref;
|
|
LLVM_DEBUG(dbgs() << " -> index:" << Ref.Segment << "\n");
|
|
} else {
|
|
report_fatal_error("don't yet support global/tag aliases");
|
|
}
|
|
}
|
|
}
|
|
|
|
// Finally, populate the symbol table itself, in its "natural" order.
|
|
for (const MCSymbol &S : Asm.symbols()) {
|
|
const auto &WS = static_cast<const MCSymbolWasm &>(S);
|
|
if (!isInSymtab(WS)) {
|
|
WS.setIndex(InvalidIndex);
|
|
continue;
|
|
}
|
|
LLVM_DEBUG(dbgs() << "adding to symtab: " << WS << "\n");
|
|
|
|
uint32_t Flags = 0;
|
|
if (WS.isWeak())
|
|
Flags |= wasm::WASM_SYMBOL_BINDING_WEAK;
|
|
if (WS.isHidden())
|
|
Flags |= wasm::WASM_SYMBOL_VISIBILITY_HIDDEN;
|
|
if (!WS.isExternal() && WS.isDefined())
|
|
Flags |= wasm::WASM_SYMBOL_BINDING_LOCAL;
|
|
if (WS.isUndefined())
|
|
Flags |= wasm::WASM_SYMBOL_UNDEFINED;
|
|
if (WS.isNoStrip()) {
|
|
Flags |= wasm::WASM_SYMBOL_NO_STRIP;
|
|
if (isEmscripten()) {
|
|
Flags |= wasm::WASM_SYMBOL_EXPORTED;
|
|
}
|
|
}
|
|
if (WS.hasImportName())
|
|
Flags |= wasm::WASM_SYMBOL_EXPLICIT_NAME;
|
|
if (WS.hasExportName())
|
|
Flags |= wasm::WASM_SYMBOL_EXPORTED;
|
|
|
|
wasm::WasmSymbolInfo Info;
|
|
Info.Name = WS.getName();
|
|
Info.Kind = WS.getType().getValueOr(wasm::WASM_SYMBOL_TYPE_DATA);
|
|
Info.Flags = Flags;
|
|
if (!WS.isData()) {
|
|
assert(WasmIndices.count(&WS) > 0);
|
|
Info.ElementIndex = WasmIndices.find(&WS)->second;
|
|
} else if (WS.isDefined()) {
|
|
assert(DataLocations.count(&WS) > 0);
|
|
Info.DataRef = DataLocations.find(&WS)->second;
|
|
}
|
|
WS.setIndex(SymbolInfos.size());
|
|
SymbolInfos.emplace_back(Info);
|
|
}
|
|
|
|
{
|
|
auto HandleReloc = [&](const WasmRelocationEntry &Rel) {
|
|
// Functions referenced by a relocation need to put in the table. This is
|
|
// purely to make the object file's provisional values readable, and is
|
|
// ignored by the linker, which re-calculates the relocations itself.
|
|
if (Rel.Type != wasm::R_WASM_TABLE_INDEX_I32 &&
|
|
Rel.Type != wasm::R_WASM_TABLE_INDEX_I64 &&
|
|
Rel.Type != wasm::R_WASM_TABLE_INDEX_SLEB &&
|
|
Rel.Type != wasm::R_WASM_TABLE_INDEX_SLEB64 &&
|
|
Rel.Type != wasm::R_WASM_TABLE_INDEX_REL_SLEB &&
|
|
Rel.Type != wasm::R_WASM_TABLE_INDEX_REL_SLEB64)
|
|
return;
|
|
assert(Rel.Symbol->isFunction());
|
|
const MCSymbolWasm *Base =
|
|
cast<MCSymbolWasm>(Layout.getBaseSymbol(*Rel.Symbol));
|
|
uint32_t FunctionIndex = WasmIndices.find(Base)->second;
|
|
uint32_t TableIndex = TableElems.size() + InitialTableOffset;
|
|
if (TableIndices.try_emplace(Base, TableIndex).second) {
|
|
LLVM_DEBUG(dbgs() << " -> adding " << Base->getName()
|
|
<< " to table: " << TableIndex << "\n");
|
|
TableElems.push_back(FunctionIndex);
|
|
registerFunctionType(*Base);
|
|
}
|
|
};
|
|
|
|
for (const WasmRelocationEntry &RelEntry : CodeRelocations)
|
|
HandleReloc(RelEntry);
|
|
for (const WasmRelocationEntry &RelEntry : DataRelocations)
|
|
HandleReloc(RelEntry);
|
|
}
|
|
|
|
// Translate .init_array section contents into start functions.
|
|
for (const MCSection &S : Asm) {
|
|
const auto &WS = static_cast<const MCSectionWasm &>(S);
|
|
if (WS.getName().startswith(".fini_array"))
|
|
report_fatal_error(".fini_array sections are unsupported");
|
|
if (!WS.getName().startswith(".init_array"))
|
|
continue;
|
|
if (WS.getFragmentList().empty())
|
|
continue;
|
|
|
|
// init_array is expected to contain a single non-empty data fragment
|
|
if (WS.getFragmentList().size() != 3)
|
|
report_fatal_error("only one .init_array section fragment supported");
|
|
|
|
auto IT = WS.begin();
|
|
const MCFragment &EmptyFrag = *IT;
|
|
if (EmptyFrag.getKind() != MCFragment::FT_Data)
|
|
report_fatal_error(".init_array section should be aligned");
|
|
|
|
IT = std::next(IT);
|
|
const MCFragment &AlignFrag = *IT;
|
|
if (AlignFrag.getKind() != MCFragment::FT_Align)
|
|
report_fatal_error(".init_array section should be aligned");
|
|
if (cast<MCAlignFragment>(AlignFrag).getAlignment() != (is64Bit() ? 8 : 4))
|
|
report_fatal_error(".init_array section should be aligned for pointers");
|
|
|
|
const MCFragment &Frag = *std::next(IT);
|
|
if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
|
|
report_fatal_error("only data supported in .init_array section");
|
|
|
|
uint16_t Priority = UINT16_MAX;
|
|
unsigned PrefixLength = strlen(".init_array");
|
|
if (WS.getName().size() > PrefixLength) {
|
|
if (WS.getName()[PrefixLength] != '.')
|
|
report_fatal_error(
|
|
".init_array section priority should start with '.'");
|
|
if (WS.getName().substr(PrefixLength + 1).getAsInteger(10, Priority))
|
|
report_fatal_error("invalid .init_array section priority");
|
|
}
|
|
const auto &DataFrag = cast<MCDataFragment>(Frag);
|
|
const SmallVectorImpl<char> &Contents = DataFrag.getContents();
|
|
for (const uint8_t *
|
|
P = (const uint8_t *)Contents.data(),
|
|
*End = (const uint8_t *)Contents.data() + Contents.size();
|
|
P != End; ++P) {
|
|
if (*P != 0)
|
|
report_fatal_error("non-symbolic data in .init_array section");
|
|
}
|
|
for (const MCFixup &Fixup : DataFrag.getFixups()) {
|
|
assert(Fixup.getKind() ==
|
|
MCFixup::getKindForSize(is64Bit() ? 8 : 4, false));
|
|
const MCExpr *Expr = Fixup.getValue();
|
|
auto *SymRef = dyn_cast<MCSymbolRefExpr>(Expr);
|
|
if (!SymRef)
|
|
report_fatal_error("fixups in .init_array should be symbol references");
|
|
const auto &TargetSym = cast<const MCSymbolWasm>(SymRef->getSymbol());
|
|
if (TargetSym.getIndex() == InvalidIndex)
|
|
report_fatal_error("symbols in .init_array should exist in symtab");
|
|
if (!TargetSym.isFunction())
|
|
report_fatal_error("symbols in .init_array should be for functions");
|
|
InitFuncs.push_back(
|
|
std::make_pair(Priority, TargetSym.getIndex()));
|
|
}
|
|
}
|
|
|
|
// Write out the Wasm header.
|
|
writeHeader(Asm);
|
|
|
|
uint32_t CodeSectionIndex, DataSectionIndex;
|
|
if (Mode != DwoMode::DwoOnly) {
|
|
writeTypeSection(Signatures);
|
|
writeImportSection(Imports, DataSize, TableElems.size());
|
|
writeFunctionSection(Functions);
|
|
writeTableSection(Tables);
|
|
// Skip the "memory" section; we import the memory instead.
|
|
writeTagSection(Tags);
|
|
writeGlobalSection(Globals);
|
|
writeExportSection(Exports);
|
|
const MCSymbol *IndirectFunctionTable =
|
|
Asm.getContext().lookupSymbol("__indirect_function_table");
|
|
writeElemSection(cast_or_null<const MCSymbolWasm>(IndirectFunctionTable),
|
|
TableElems);
|
|
writeDataCountSection();
|
|
|
|
CodeSectionIndex = writeCodeSection(Asm, Layout, Functions);
|
|
DataSectionIndex = writeDataSection(Layout);
|
|
}
|
|
|
|
// The Sections in the COMDAT list have placeholder indices (their index among
|
|
// custom sections, rather than among all sections). Fix them up here.
|
|
for (auto &Group : Comdats) {
|
|
for (auto &Entry : Group.second) {
|
|
if (Entry.Kind == wasm::WASM_COMDAT_SECTION) {
|
|
Entry.Index += SectionCount;
|
|
}
|
|
}
|
|
}
|
|
for (auto &CustomSection : CustomSections)
|
|
writeCustomSection(CustomSection, Asm, Layout);
|
|
|
|
if (Mode != DwoMode::DwoOnly) {
|
|
writeLinkingMetaDataSection(SymbolInfos, InitFuncs, Comdats);
|
|
|
|
writeRelocSection(CodeSectionIndex, "CODE", CodeRelocations);
|
|
writeRelocSection(DataSectionIndex, "DATA", DataRelocations);
|
|
}
|
|
writeCustomRelocSections();
|
|
if (ProducersSection)
|
|
writeCustomSection(*ProducersSection, Asm, Layout);
|
|
if (TargetFeaturesSection)
|
|
writeCustomSection(*TargetFeaturesSection, Asm, Layout);
|
|
|
|
// TODO: Translate the .comment section to the output.
|
|
return W->OS.tell() - StartOffset;
|
|
}
|
|
|
|
std::unique_ptr<MCObjectWriter>
|
|
llvm::createWasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
|
|
raw_pwrite_stream &OS) {
|
|
return std::make_unique<WasmObjectWriter>(std::move(MOTW), OS);
|
|
}
|
|
|
|
std::unique_ptr<MCObjectWriter>
|
|
llvm::createWasmDwoObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
|
|
raw_pwrite_stream &OS,
|
|
raw_pwrite_stream &DwoOS) {
|
|
return std::make_unique<WasmObjectWriter>(std::move(MOTW), OS, DwoOS);
|
|
}
|