Files
clang-p2996/llvm/tools/obj2yaml/wasm2yaml.cpp
Nick Fitzgerald 6018930ef1 [lld][WebAssembly] Support for the custom-page-sizes WebAssembly proposal (#128942)
This commit adds support for WebAssembly's custom-page-sizes proposal to
`wasm-ld`. An overview of the proposal can be found
[here](https://github.com/WebAssembly/custom-page-sizes/blob/main/proposals/custom-page-sizes/Overview.md).
In a sentence, it allows customizing a Wasm memory's page size, enabling
Wasm to target environments with less than 64KiB of memory (the default
Wasm page size) available for Wasm memories.

This commit contains the following:

* Adds a `--page-size=N` CLI flag to `wasm-ld` for configuring the
linked Wasm binary's linear memory's page size.

* When the page size is configured to a non-default value, then the
final Wasm binary will use the encodings defined in the
custom-page-sizes proposal to declare the linear memory's page size.

* Defines a `__wasm_first_page_end` symbol, whose address points to the
first page in the Wasm linear memory, a.k.a. is the Wasm memory's page
size. This allows writing code that is compatible with any page size,
and doesn't require re-compiling its object code. At the same time,
because it just lowers to a constant rather than a memory access or
something, it enables link-time optimization.

* Adds tests for these new features.

r? @sbc100 

cc @sunfishcode
2025-03-04 09:39:30 -08:00

436 lines
15 KiB
C++

//===------ utils/wasm2yaml.cpp - obj2yaml conversion tool ------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "obj2yaml.h"
#include "llvm/Object/COFF.h"
#include "llvm/ObjectYAML/WasmYAML.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/YAMLTraits.h"
using namespace llvm;
using object::WasmSection;
namespace {
class WasmDumper {
const object::WasmObjectFile &Obj;
public:
WasmDumper(const object::WasmObjectFile &O) : Obj(O) {}
ErrorOr<WasmYAML::Object *> dump();
std::unique_ptr<WasmYAML::CustomSection>
dumpCustomSection(const WasmSection &WasmSec);
};
} // namespace
static WasmYAML::Limits makeLimits(const wasm::WasmLimits &Limits) {
WasmYAML::Limits L;
L.Flags = Limits.Flags;
L.Minimum = Limits.Minimum;
L.Maximum = Limits.Maximum;
L.PageSize = Limits.PageSize;
return L;
}
static WasmYAML::Table makeTable(uint32_t Index,
const wasm::WasmTableType &Type) {
WasmYAML::Table T;
T.Index = Index;
T.ElemType = (uint32_t)Type.ElemType;
T.TableLimits = makeLimits(Type.Limits);
return T;
}
std::unique_ptr<WasmYAML::CustomSection>
WasmDumper::dumpCustomSection(const WasmSection &WasmSec) {
std::unique_ptr<WasmYAML::CustomSection> CustomSec;
if (WasmSec.Name == "dylink" || WasmSec.Name == "dylink.0") {
std::unique_ptr<WasmYAML::DylinkSection> DylinkSec =
std::make_unique<WasmYAML::DylinkSection>();
const wasm::WasmDylinkInfo& Info = Obj.dylinkInfo();
DylinkSec->MemorySize = Info.MemorySize;
DylinkSec->MemoryAlignment = Info.MemoryAlignment;
DylinkSec->TableSize = Info.TableSize;
DylinkSec->TableAlignment = Info.TableAlignment;
DylinkSec->Needed = Info.Needed;
DylinkSec->RuntimePath = Info.RuntimePath;
for (const auto &Imp : Info.ImportInfo)
DylinkSec->ImportInfo.push_back({Imp.Module, Imp.Field, Imp.Flags});
for (const auto &Exp : Info.ExportInfo)
DylinkSec->ExportInfo.push_back({Exp.Name, Exp.Flags});
CustomSec = std::move(DylinkSec);
} else if (WasmSec.Name == "name") {
std::unique_ptr<WasmYAML::NameSection> NameSec =
std::make_unique<WasmYAML::NameSection>();
for (const llvm::wasm::WasmDebugName &Name : Obj.debugNames()) {
WasmYAML::NameEntry NameEntry;
NameEntry.Name = Name.Name;
NameEntry.Index = Name.Index;
if (Name.Type == llvm::wasm::NameType::FUNCTION) {
NameSec->FunctionNames.push_back(NameEntry);
} else if (Name.Type == llvm::wasm::NameType::GLOBAL) {
NameSec->GlobalNames.push_back(NameEntry);
} else {
assert(Name.Type == llvm::wasm::NameType::DATA_SEGMENT);
NameSec->DataSegmentNames.push_back(NameEntry);
}
}
CustomSec = std::move(NameSec);
} else if (WasmSec.Name == "linking") {
std::unique_ptr<WasmYAML::LinkingSection> LinkingSec =
std::make_unique<WasmYAML::LinkingSection>();
LinkingSec->Version = Obj.linkingData().Version;
ArrayRef<StringRef> Comdats = Obj.linkingData().Comdats;
for (StringRef ComdatName : Comdats)
LinkingSec->Comdats.emplace_back(WasmYAML::Comdat{ComdatName, {}});
for (auto &Func : Obj.functions()) {
if (Func.Comdat != UINT32_MAX) {
LinkingSec->Comdats[Func.Comdat].Entries.emplace_back(
WasmYAML::ComdatEntry{wasm::WASM_COMDAT_FUNCTION, Func.Index});
}
}
uint32_t SegmentIndex = 0;
for (const object::WasmSegment &Segment : Obj.dataSegments()) {
if (!Segment.Data.Name.empty()) {
WasmYAML::SegmentInfo SegmentInfo;
SegmentInfo.Name = Segment.Data.Name;
SegmentInfo.Index = SegmentIndex;
SegmentInfo.Alignment = Segment.Data.Alignment;
SegmentInfo.Flags = Segment.Data.LinkingFlags;
LinkingSec->SegmentInfos.push_back(SegmentInfo);
}
if (Segment.Data.Comdat != UINT32_MAX) {
LinkingSec->Comdats[Segment.Data.Comdat].Entries.emplace_back(
WasmYAML::ComdatEntry{wasm::WASM_COMDAT_DATA, SegmentIndex});
}
SegmentIndex++;
}
uint32_t SectionIndex = 0;
for (const auto &Sec : Obj.sections()) {
const WasmSection &WasmSec = Obj.getWasmSection(Sec);
if (WasmSec.Comdat != UINT32_MAX)
LinkingSec->Comdats[WasmSec.Comdat].Entries.emplace_back(
WasmYAML::ComdatEntry{wasm::WASM_COMDAT_SECTION, SectionIndex});
SectionIndex++;
}
uint32_t SymbolIndex = 0;
for (const object::SymbolRef &Sym : Obj.symbols()) {
const wasm::WasmSymbolInfo &Symbol = Obj.getWasmSymbol(Sym).Info;
WasmYAML::SymbolInfo Info;
Info.Index = SymbolIndex++;
Info.Kind = static_cast<uint32_t>(Symbol.Kind);
Info.Name = Symbol.Name;
Info.Flags = Symbol.Flags;
switch (Symbol.Kind) {
case wasm::WASM_SYMBOL_TYPE_DATA:
Info.DataRef = Symbol.DataRef;
break;
case wasm::WASM_SYMBOL_TYPE_FUNCTION:
case wasm::WASM_SYMBOL_TYPE_GLOBAL:
case wasm::WASM_SYMBOL_TYPE_TABLE:
case wasm::WASM_SYMBOL_TYPE_TAG:
Info.ElementIndex = Symbol.ElementIndex;
break;
case wasm::WASM_SYMBOL_TYPE_SECTION:
Info.ElementIndex = Symbol.ElementIndex;
break;
}
LinkingSec->SymbolTable.emplace_back(Info);
}
for (const wasm::WasmInitFunc &Func : Obj.linkingData().InitFunctions) {
WasmYAML::InitFunction F{Func.Priority, Func.Symbol};
LinkingSec->InitFunctions.emplace_back(F);
}
CustomSec = std::move(LinkingSec);
} else if (WasmSec.Name == "producers") {
std::unique_ptr<WasmYAML::ProducersSection> ProducersSec =
std::make_unique<WasmYAML::ProducersSection>();
const llvm::wasm::WasmProducerInfo &Info = Obj.getProducerInfo();
for (auto &E : Info.Languages) {
WasmYAML::ProducerEntry Producer;
Producer.Name = E.first;
Producer.Version = E.second;
ProducersSec->Languages.push_back(Producer);
}
for (auto &E : Info.Tools) {
WasmYAML::ProducerEntry Producer;
Producer.Name = E.first;
Producer.Version = E.second;
ProducersSec->Tools.push_back(Producer);
}
for (auto &E : Info.SDKs) {
WasmYAML::ProducerEntry Producer;
Producer.Name = E.first;
Producer.Version = E.second;
ProducersSec->SDKs.push_back(Producer);
}
CustomSec = std::move(ProducersSec);
} else if (WasmSec.Name == "target_features") {
std::unique_ptr<WasmYAML::TargetFeaturesSection> TargetFeaturesSec =
std::make_unique<WasmYAML::TargetFeaturesSection>();
for (auto &E : Obj.getTargetFeatures()) {
WasmYAML::FeatureEntry Feature;
Feature.Prefix = E.Prefix;
Feature.Name = E.Name;
TargetFeaturesSec->Features.push_back(Feature);
}
CustomSec = std::move(TargetFeaturesSec);
} else {
CustomSec = std::make_unique<WasmYAML::CustomSection>(WasmSec.Name);
}
CustomSec->Payload = yaml::BinaryRef(WasmSec.Content);
return CustomSec;
}
ErrorOr<WasmYAML::Object *> WasmDumper::dump() {
auto Y = std::make_unique<WasmYAML::Object>();
// Dump header
Y->Header.Version = Obj.getHeader().Version;
// Dump sections
for (const auto &Sec : Obj.sections()) {
const WasmSection &WasmSec = Obj.getWasmSection(Sec);
std::unique_ptr<WasmYAML::Section> S;
switch (WasmSec.Type) {
case wasm::WASM_SEC_CUSTOM: {
if (WasmSec.Name.starts_with("reloc.")) {
// Relocations are attached the sections they apply to rather than
// being represented as a custom section in the YAML output.
continue;
}
S = dumpCustomSection(WasmSec);
break;
}
case wasm::WASM_SEC_TYPE: {
auto TypeSec = std::make_unique<WasmYAML::TypeSection>();
uint32_t Index = 0;
for (const auto &FunctionSig : Obj.types()) {
WasmYAML::Signature Sig;
Sig.Index = Index++;
for (const auto &ParamType : FunctionSig.Params)
Sig.ParamTypes.emplace_back(static_cast<uint32_t>(ParamType));
for (const auto &ReturnType : FunctionSig.Returns)
Sig.ReturnTypes.emplace_back(static_cast<uint32_t>(ReturnType));
TypeSec->Signatures.push_back(Sig);
}
S = std::move(TypeSec);
break;
}
case wasm::WASM_SEC_IMPORT: {
auto ImportSec = std::make_unique<WasmYAML::ImportSection>();
for (auto &Import : Obj.imports()) {
WasmYAML::Import Im;
Im.Module = Import.Module;
Im.Field = Import.Field;
Im.Kind = Import.Kind;
switch (Im.Kind) {
case wasm::WASM_EXTERNAL_FUNCTION:
Im.SigIndex = Import.SigIndex;
break;
case wasm::WASM_EXTERNAL_GLOBAL:
Im.GlobalImport.Type = Import.Global.Type;
Im.GlobalImport.Mutable = Import.Global.Mutable;
break;
case wasm::WASM_EXTERNAL_TAG:
Im.SigIndex = Import.SigIndex;
break;
case wasm::WASM_EXTERNAL_TABLE:
// FIXME: Currently we always output an index of 0 for any imported
// table.
Im.TableImport = makeTable(0, Import.Table);
break;
case wasm::WASM_EXTERNAL_MEMORY:
Im.Memory = makeLimits(Import.Memory);
break;
}
ImportSec->Imports.push_back(Im);
}
S = std::move(ImportSec);
break;
}
case wasm::WASM_SEC_FUNCTION: {
auto FuncSec = std::make_unique<WasmYAML::FunctionSection>();
for (const auto &Func : Obj.functions()) {
FuncSec->FunctionTypes.push_back(Func.SigIndex);
}
S = std::move(FuncSec);
break;
}
case wasm::WASM_SEC_TABLE: {
auto TableSec = std::make_unique<WasmYAML::TableSection>();
for (const wasm::WasmTable &Table : Obj.tables()) {
TableSec->Tables.push_back(makeTable(Table.Index, Table.Type));
}
S = std::move(TableSec);
break;
}
case wasm::WASM_SEC_MEMORY: {
auto MemorySec = std::make_unique<WasmYAML::MemorySection>();
for (const wasm::WasmLimits &Memory : Obj.memories()) {
MemorySec->Memories.push_back(makeLimits(Memory));
}
S = std::move(MemorySec);
break;
}
case wasm::WASM_SEC_TAG: {
auto TagSec = std::make_unique<WasmYAML::TagSection>();
for (auto &Tag : Obj.tags()) {
TagSec->TagTypes.push_back(Tag.SigIndex);
}
S = std::move(TagSec);
break;
}
case wasm::WASM_SEC_GLOBAL: {
auto GlobalSec = std::make_unique<WasmYAML::GlobalSection>();
for (auto &Global : Obj.globals()) {
WasmYAML::Global G;
G.Index = Global.Index;
G.Type = Global.Type.Type;
G.Mutable = Global.Type.Mutable;
G.Init.Extended = Global.InitExpr.Extended;
if (Global.InitExpr.Extended) {
G.Init.Body = Global.InitExpr.Body;
} else {
G.Init.Inst = Global.InitExpr.Inst;
}
GlobalSec->Globals.push_back(G);
}
S = std::move(GlobalSec);
break;
}
case wasm::WASM_SEC_START: {
auto StartSec = std::make_unique<WasmYAML::StartSection>();
StartSec->StartFunction = Obj.startFunction();
S = std::move(StartSec);
break;
}
case wasm::WASM_SEC_EXPORT: {
auto ExportSec = std::make_unique<WasmYAML::ExportSection>();
for (auto &Export : Obj.exports()) {
WasmYAML::Export Ex;
Ex.Name = Export.Name;
Ex.Kind = Export.Kind;
Ex.Index = Export.Index;
ExportSec->Exports.push_back(Ex);
}
S = std::move(ExportSec);
break;
}
case wasm::WASM_SEC_ELEM: {
auto ElemSec = std::make_unique<WasmYAML::ElemSection>();
for (auto &Segment : Obj.elements()) {
WasmYAML::ElemSegment Seg;
Seg.Flags = Segment.Flags;
Seg.TableNumber = Segment.TableNumber;
Seg.ElemKind = (uint32_t)Segment.ElemKind;
Seg.Offset.Extended = Segment.Offset.Extended;
if (Seg.Offset.Extended) {
Seg.Offset.Body = yaml::BinaryRef(Segment.Offset.Body);
} else {
Seg.Offset.Inst = Segment.Offset.Inst;
}
append_range(Seg.Functions, Segment.Functions);
ElemSec->Segments.push_back(Seg);
}
S = std::move(ElemSec);
break;
}
case wasm::WASM_SEC_CODE: {
auto CodeSec = std::make_unique<WasmYAML::CodeSection>();
for (auto &Func : Obj.functions()) {
WasmYAML::Function Function;
Function.Index = Func.Index;
for (auto &Local : Func.Locals) {
WasmYAML::LocalDecl LocalDecl;
LocalDecl.Type = Local.Type;
LocalDecl.Count = Local.Count;
Function.Locals.push_back(LocalDecl);
}
Function.Body = yaml::BinaryRef(Func.Body);
CodeSec->Functions.push_back(Function);
}
S = std::move(CodeSec);
break;
}
case wasm::WASM_SEC_DATA: {
auto DataSec = std::make_unique<WasmYAML::DataSection>();
for (const object::WasmSegment &Segment : Obj.dataSegments()) {
WasmYAML::DataSegment Seg;
Seg.SectionOffset = Segment.SectionOffset;
Seg.InitFlags = Segment.Data.InitFlags;
Seg.MemoryIndex = Segment.Data.MemoryIndex;
Seg.Offset.Extended = Segment.Data.Offset.Extended;
if (Seg.Offset.Extended) {
Seg.Offset.Body = yaml::BinaryRef(Segment.Data.Offset.Body);
} else {
Seg.Offset.Inst = Segment.Data.Offset.Inst;
}
Seg.Content = yaml::BinaryRef(Segment.Data.Content);
DataSec->Segments.push_back(Seg);
}
S = std::move(DataSec);
break;
}
case wasm::WASM_SEC_DATACOUNT: {
auto DataCountSec = std::make_unique<WasmYAML::DataCountSection>();
DataCountSec->Count = Obj.dataSegments().size();
S = std::move(DataCountSec);
break;
}
default:
llvm_unreachable("Unknown section type");
break;
}
// Only propagate the section size encoding length if it's not the minimal
// size or 5 (the default "padded" value). This is to avoid having every
// YAML output polluted with this value when we usually don't care about it
// (and avoid rewriting all the test expectations).
if (WasmSec.HeaderSecSizeEncodingLen &&
WasmSec.HeaderSecSizeEncodingLen !=
getULEB128Size(WasmSec.Content.size()) &&
WasmSec.HeaderSecSizeEncodingLen != 5)
S->HeaderSecSizeEncodingLen = WasmSec.HeaderSecSizeEncodingLen;
for (const wasm::WasmRelocation &Reloc : WasmSec.Relocations) {
WasmYAML::Relocation R;
R.Type = Reloc.Type;
R.Index = Reloc.Index;
R.Offset = Reloc.Offset;
R.Addend = Reloc.Addend;
S->Relocations.push_back(R);
}
Y->Sections.push_back(std::move(S));
}
return Y.release();
}
std::error_code wasm2yaml(raw_ostream &Out, const object::WasmObjectFile &Obj) {
WasmDumper Dumper(Obj);
ErrorOr<WasmYAML::Object *> YAMLOrErr = Dumper.dump();
if (std::error_code EC = YAMLOrErr.getError())
return EC;
std::unique_ptr<WasmYAML::Object> YAML(YAMLOrErr.get());
yaml::Output Yout(Out);
Yout << *YAML;
return std::error_code();
}