wasmtime_environ/compile/module_environ.rs
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use crate::module::{
FuncRefIndex, Initializer, MemoryInitialization, MemoryInitializer, Module, TableSegment,
TableSegmentElements,
};
use crate::prelude::*;
use crate::{
ConstExpr, ConstOp, DataIndex, DefinedFuncIndex, ElemIndex, EngineOrModuleTypeIndex,
EntityIndex, EntityType, FuncIndex, GlobalIndex, IndexType, InitMemory, MemoryIndex,
ModuleInternedTypeIndex, ModuleTypesBuilder, PrimaryMap, SizeOverflow, StaticMemoryInitializer,
TableIndex, TableInitialValue, Tunables, TypeConvert, TypeIndex, Unsigned, WasmError,
WasmHeapTopType, WasmHeapType, WasmResult, WasmValType, WasmparserTypeConverter,
};
use anyhow::{bail, Result};
use cranelift_entity::packed_option::ReservedValue;
use std::borrow::Cow;
use std::collections::HashMap;
use std::mem;
use std::path::PathBuf;
use std::sync::Arc;
use wasmparser::{
types::Types, CustomSectionReader, DataKind, ElementItems, ElementKind, Encoding, ExternalKind,
FuncToValidate, FunctionBody, KnownCustom, NameSectionReader, Naming, Parser, Payload, TypeRef,
Validator, ValidatorResources,
};
/// Object containing the standalone environment information.
pub struct ModuleEnvironment<'a, 'data> {
/// The current module being translated
result: ModuleTranslation<'data>,
/// Intern'd types for this entire translation, shared by all modules.
types: &'a mut ModuleTypesBuilder,
// Various bits and pieces of configuration
validator: &'a mut Validator,
tunables: &'a Tunables,
}
/// The result of translating via `ModuleEnvironment`. Function bodies are not
/// yet translated, and data initializers have not yet been copied out of the
/// original buffer.
#[derive(Default)]
pub struct ModuleTranslation<'data> {
/// Module information.
pub module: Module,
/// The input wasm binary.
///
/// This can be useful, for example, when modules are parsed from a
/// component and the embedder wants access to the raw wasm modules
/// themselves.
pub wasm: &'data [u8],
/// References to the function bodies.
pub function_body_inputs: PrimaryMap<DefinedFuncIndex, FunctionBodyData<'data>>,
/// A list of type signatures which are considered exported from this
/// module, or those that can possibly be called. This list is sorted, and
/// trampolines for each of these signatures are required.
pub exported_signatures: Vec<ModuleInternedTypeIndex>,
/// DWARF debug information, if enabled, parsed from the module.
pub debuginfo: DebugInfoData<'data>,
/// Set if debuginfo was found but it was not parsed due to `Tunables`
/// configuration.
pub has_unparsed_debuginfo: bool,
/// List of data segments found in this module which should be concatenated
/// together for the final compiled artifact.
///
/// These data segments, when concatenated, are indexed by the
/// `MemoryInitializer` type.
pub data: Vec<Cow<'data, [u8]>>,
/// The desired alignment of `data` in the final data section of the object
/// file that we'll emit.
///
/// Note that this is 1 by default but `MemoryInitialization::Static` might
/// switch this to a higher alignment to facilitate mmap-ing data from
/// an object file into a linear memory.
pub data_align: Option<u64>,
/// Total size of all data pushed onto `data` so far.
total_data: u32,
/// List of passive element segments found in this module which will get
/// concatenated for the final artifact.
pub passive_data: Vec<&'data [u8]>,
/// Total size of all passive data pushed into `passive_data` so far.
total_passive_data: u32,
/// When we're parsing the code section this will be incremented so we know
/// which function is currently being defined.
code_index: u32,
/// The type information of the current module made available at the end of the
/// validation process.
types: Option<Types>,
}
impl<'data> ModuleTranslation<'data> {
/// Returns a reference to the type information of the current module.
pub fn get_types(&self) -> &Types {
self.types
.as_ref()
.expect("module type information to be available")
}
}
/// Contains function data: byte code and its offset in the module.
pub struct FunctionBodyData<'a> {
/// The body of the function, containing code and locals.
pub body: FunctionBody<'a>,
/// Validator for the function body
pub validator: FuncToValidate<ValidatorResources>,
}
#[derive(Debug, Default)]
#[allow(missing_docs)]
pub struct DebugInfoData<'a> {
pub dwarf: Dwarf<'a>,
pub name_section: NameSection<'a>,
pub wasm_file: WasmFileInfo,
pub debug_loc: gimli::DebugLoc<Reader<'a>>,
pub debug_loclists: gimli::DebugLocLists<Reader<'a>>,
pub debug_ranges: gimli::DebugRanges<Reader<'a>>,
pub debug_rnglists: gimli::DebugRngLists<Reader<'a>>,
pub debug_cu_index: gimli::DebugCuIndex<Reader<'a>>,
pub debug_tu_index: gimli::DebugTuIndex<Reader<'a>>,
}
#[allow(missing_docs)]
pub type Dwarf<'input> = gimli::Dwarf<Reader<'input>>;
type Reader<'input> = gimli::EndianSlice<'input, gimli::LittleEndian>;
#[derive(Debug, Default)]
#[allow(missing_docs)]
pub struct NameSection<'a> {
pub module_name: Option<&'a str>,
pub func_names: HashMap<FuncIndex, &'a str>,
pub locals_names: HashMap<FuncIndex, HashMap<u32, &'a str>>,
}
#[derive(Debug, Default)]
#[allow(missing_docs)]
pub struct WasmFileInfo {
pub path: Option<PathBuf>,
pub code_section_offset: u64,
pub imported_func_count: u32,
pub funcs: Vec<FunctionMetadata>,
}
#[derive(Debug)]
#[allow(missing_docs)]
pub struct FunctionMetadata {
pub params: Box<[WasmValType]>,
pub locals: Box<[(u32, WasmValType)]>,
}
impl<'a, 'data> ModuleEnvironment<'a, 'data> {
/// Allocates the environment data structures.
pub fn new(
tunables: &'a Tunables,
validator: &'a mut Validator,
types: &'a mut ModuleTypesBuilder,
) -> Self {
Self {
result: ModuleTranslation::default(),
types,
tunables,
validator,
}
}
/// Translate a wasm module using this environment.
///
/// This function will translate the `data` provided with `parser`,
/// validating everything along the way with this environment's validator.
///
/// The result of translation, [`ModuleTranslation`], contains everything
/// necessary to compile functions afterwards as well as learn type
/// information about the module at runtime.
pub fn translate(
mut self,
parser: Parser,
data: &'data [u8],
) -> Result<ModuleTranslation<'data>> {
self.result.wasm = data;
for payload in parser.parse_all(data) {
self.translate_payload(payload?)?;
}
Ok(self.result)
}
fn translate_payload(&mut self, payload: Payload<'data>) -> Result<()> {
match payload {
Payload::Version {
num,
encoding,
range,
} => {
self.validator.version(num, encoding, &range)?;
match encoding {
Encoding::Module => {}
Encoding::Component => {
bail!("expected a WebAssembly module but was given a WebAssembly component")
}
}
}
Payload::End(offset) => {
self.result.types = Some(self.validator.end(offset)?);
// With the `escaped_funcs` set of functions finished
// we can calculate the set of signatures that are exported as
// the set of exported functions' signatures.
self.result.exported_signatures = self
.result
.module
.functions
.iter()
.filter_map(|(_, func)| {
if func.is_escaping() {
Some(func.signature)
} else {
None
}
})
.collect();
self.result.exported_signatures.sort_unstable();
self.result.exported_signatures.dedup();
}
Payload::TypeSection(types) => {
self.validator.type_section(&types)?;
let count = self.validator.types(0).unwrap().core_type_count_in_module();
log::trace!("interning {count} Wasm types");
let capacity = usize::try_from(count).unwrap();
self.result.module.types.reserve(capacity);
self.types.reserve_wasm_signatures(capacity);
// Iterate over each *rec group* -- not type -- defined in the
// types section. Rec groups are the unit of canonicalization
// and therefore the unit at which we need to process at a
// time. `wasmparser` has already done the hard work of
// de-duplicating and canonicalizing the rec groups within the
// module for us, we just need to translate them into our data
// structures. Note that, if the Wasm defines duplicate rec
// groups, we need copy the duplicates over (shallowly) as well,
// so that our types index space doesn't have holes.
let mut type_index = 0;
while type_index < count {
let validator_types = self.validator.types(0).unwrap();
// Get the rec group for the current type index, which is
// always the first type defined in a rec group.
log::trace!("looking up wasmparser type for index {type_index}");
let core_type_id = validator_types.core_type_at_in_module(type_index);
log::trace!(
" --> {core_type_id:?} = {:?}",
validator_types[core_type_id],
);
let rec_group_id = validator_types.rec_group_id_of(core_type_id);
debug_assert_eq!(
validator_types
.rec_group_elements(rec_group_id)
.position(|id| id == core_type_id),
Some(0)
);
// Intern the rec group and then fill in this module's types
// index space.
let interned = self.types.intern_rec_group(validator_types, rec_group_id)?;
let elems = self.types.rec_group_elements(interned);
let len = elems.len();
self.result.module.types.reserve(len);
for ty in elems {
self.result.module.types.push(ty);
}
// Advance `type_index` to the start of the next rec group.
type_index += u32::try_from(len).unwrap();
}
}
Payload::ImportSection(imports) => {
self.validator.import_section(&imports)?;
let cnt = usize::try_from(imports.count()).unwrap();
self.result.module.initializers.reserve(cnt);
for entry in imports {
let import = entry?;
let ty = match import.ty {
TypeRef::Func(index) => {
let index = TypeIndex::from_u32(index);
let interned_index = self.result.module.types[index];
self.result.module.num_imported_funcs += 1;
self.result.debuginfo.wasm_file.imported_func_count += 1;
EntityType::Function(EngineOrModuleTypeIndex::Module(interned_index))
}
TypeRef::Memory(ty) => {
self.result.module.num_imported_memories += 1;
EntityType::Memory(ty.into())
}
TypeRef::Global(ty) => {
self.result.module.num_imported_globals += 1;
EntityType::Global(self.convert_global_type(&ty))
}
TypeRef::Table(ty) => {
self.result.module.num_imported_tables += 1;
EntityType::Table(self.convert_table_type(&ty)?)
}
// doesn't get past validation
TypeRef::Tag(_) => unreachable!(),
};
self.declare_import(import.module, import.name, ty);
}
}
Payload::FunctionSection(functions) => {
self.validator.function_section(&functions)?;
let cnt = usize::try_from(functions.count()).unwrap();
self.result.module.functions.reserve_exact(cnt);
for entry in functions {
let sigindex = entry?;
let ty = TypeIndex::from_u32(sigindex);
let interned_index = self.result.module.types[ty];
self.result.module.push_function(interned_index);
}
}
Payload::TableSection(tables) => {
self.validator.table_section(&tables)?;
let cnt = usize::try_from(tables.count()).unwrap();
self.result.module.tables.reserve_exact(cnt);
for entry in tables {
let wasmparser::Table { ty, init } = entry?;
let table = self.convert_table_type(&ty)?;
self.result.module.tables.push(table);
let init = match init {
wasmparser::TableInit::RefNull => TableInitialValue::Null {
precomputed: Vec::new(),
},
wasmparser::TableInit::Expr(expr) => {
let (init, escaped) = ConstExpr::from_wasmparser(expr)?;
for f in escaped {
self.flag_func_escaped(f);
}
TableInitialValue::Expr(init)
}
};
self.result
.module
.table_initialization
.initial_values
.push(init);
}
}
Payload::MemorySection(memories) => {
self.validator.memory_section(&memories)?;
let cnt = usize::try_from(memories.count()).unwrap();
self.result.module.memories.reserve_exact(cnt);
for entry in memories {
let memory = entry?;
self.result.module.memories.push(memory.into());
}
}
Payload::TagSection(tags) => {
self.validator.tag_section(&tags)?;
// This feature isn't enabled at this time, so we should
// never get here.
unreachable!();
}
Payload::GlobalSection(globals) => {
self.validator.global_section(&globals)?;
let cnt = usize::try_from(globals.count()).unwrap();
self.result.module.globals.reserve_exact(cnt);
for entry in globals {
let wasmparser::Global { ty, init_expr } = entry?;
let (initializer, escaped) = ConstExpr::from_wasmparser(init_expr)?;
for f in escaped {
self.flag_func_escaped(f);
}
let ty = self.convert_global_type(&ty);
self.result.module.globals.push(ty);
self.result.module.global_initializers.push(initializer);
}
}
Payload::ExportSection(exports) => {
self.validator.export_section(&exports)?;
let cnt = usize::try_from(exports.count()).unwrap();
self.result.module.exports.reserve(cnt);
for entry in exports {
let wasmparser::Export { name, kind, index } = entry?;
let entity = match kind {
ExternalKind::Func => {
let index = FuncIndex::from_u32(index);
self.flag_func_escaped(index);
EntityIndex::Function(index)
}
ExternalKind::Table => EntityIndex::Table(TableIndex::from_u32(index)),
ExternalKind::Memory => EntityIndex::Memory(MemoryIndex::from_u32(index)),
ExternalKind::Global => EntityIndex::Global(GlobalIndex::from_u32(index)),
// this never gets past validation
ExternalKind::Tag => unreachable!(),
};
self.result
.module
.exports
.insert(String::from(name), entity);
}
}
Payload::StartSection { func, range } => {
self.validator.start_section(func, &range)?;
let func_index = FuncIndex::from_u32(func);
self.flag_func_escaped(func_index);
debug_assert!(self.result.module.start_func.is_none());
self.result.module.start_func = Some(func_index);
}
Payload::ElementSection(elements) => {
self.validator.element_section(&elements)?;
for (index, entry) in elements.into_iter().enumerate() {
let wasmparser::Element {
kind,
items,
range: _,
} = entry?;
// Build up a list of `FuncIndex` corresponding to all the
// entries listed in this segment. Note that it's not
// possible to create anything other than a `ref.null
// extern` for externref segments, so those just get
// translated to the reserved value of `FuncIndex`.
let elements = match items {
ElementItems::Functions(funcs) => {
let mut elems =
Vec::with_capacity(usize::try_from(funcs.count()).unwrap());
for func in funcs {
let func = FuncIndex::from_u32(func?);
self.flag_func_escaped(func);
elems.push(func);
}
TableSegmentElements::Functions(elems.into())
}
ElementItems::Expressions(_ty, items) => {
let mut exprs =
Vec::with_capacity(usize::try_from(items.count()).unwrap());
for expr in items {
let (expr, escaped) = ConstExpr::from_wasmparser(expr?)?;
exprs.push(expr);
for func in escaped {
self.flag_func_escaped(func);
}
}
TableSegmentElements::Expressions(exprs.into())
}
};
match kind {
ElementKind::Active {
table_index,
offset_expr,
} => {
let table_index = TableIndex::from_u32(table_index.unwrap_or(0));
let (offset, escaped) = ConstExpr::from_wasmparser(offset_expr)?;
debug_assert!(escaped.is_empty());
self.result
.module
.table_initialization
.segments
.push(TableSegment {
table_index,
offset,
elements: elements.into(),
});
}
ElementKind::Passive => {
let elem_index = ElemIndex::from_u32(index as u32);
let index = self.result.module.passive_elements.len();
self.result.module.passive_elements.push(elements.into());
self.result
.module
.passive_elements_map
.insert(elem_index, index);
}
ElementKind::Declared => {}
}
}
}
Payload::CodeSectionStart { count, range, .. } => {
self.validator.code_section_start(count, &range)?;
let cnt = usize::try_from(count).unwrap();
self.result.function_body_inputs.reserve_exact(cnt);
self.result.debuginfo.wasm_file.code_section_offset = range.start as u64;
}
Payload::CodeSectionEntry(body) => {
let validator = self.validator.code_section_entry(&body)?;
let func_index =
self.result.code_index + self.result.module.num_imported_funcs as u32;
let func_index = FuncIndex::from_u32(func_index);
if self.tunables.generate_native_debuginfo {
let sig_index = self.result.module.functions[func_index].signature;
let sig = self.types[sig_index].unwrap_func();
let mut locals = Vec::new();
for pair in body.get_locals_reader()? {
let (cnt, ty) = pair?;
let ty = self.convert_valtype(ty);
locals.push((cnt, ty));
}
self.result
.debuginfo
.wasm_file
.funcs
.push(FunctionMetadata {
locals: locals.into_boxed_slice(),
params: sig.params().into(),
});
}
self.result
.function_body_inputs
.push(FunctionBodyData { validator, body });
self.result.code_index += 1;
}
Payload::DataSection(data) => {
self.validator.data_section(&data)?;
let initializers = match &mut self.result.module.memory_initialization {
MemoryInitialization::Segmented(i) => i,
_ => unreachable!(),
};
let cnt = usize::try_from(data.count()).unwrap();
initializers.reserve_exact(cnt);
self.result.data.reserve_exact(cnt);
for (index, entry) in data.into_iter().enumerate() {
let wasmparser::Data {
kind,
data,
range: _,
} = entry?;
let mk_range = |total: &mut u32| -> Result<_, WasmError> {
let range = u32::try_from(data.len())
.ok()
.and_then(|size| {
let start = *total;
let end = start.checked_add(size)?;
Some(start..end)
})
.ok_or_else(|| {
WasmError::Unsupported(format!(
"more than 4 gigabytes of data in wasm module",
))
})?;
*total += range.end - range.start;
Ok(range)
};
match kind {
DataKind::Active {
memory_index,
offset_expr,
} => {
let range = mk_range(&mut self.result.total_data)?;
let memory_index = MemoryIndex::from_u32(memory_index);
let (offset, escaped) = ConstExpr::from_wasmparser(offset_expr)?;
debug_assert!(escaped.is_empty());
initializers.push(MemoryInitializer {
memory_index,
offset,
data: range,
});
self.result.data.push(data.into());
}
DataKind::Passive => {
let data_index = DataIndex::from_u32(index as u32);
let range = mk_range(&mut self.result.total_passive_data)?;
self.result.passive_data.push(data);
self.result
.module
.passive_data_map
.insert(data_index, range);
}
}
}
}
Payload::DataCountSection { count, range } => {
self.validator.data_count_section(count, &range)?;
// Note: the count passed in here is the *total* segment count
// There is no way to reserve for just the passive segments as
// they are discovered when iterating the data section entries
// Given that the total segment count might be much larger than
// the passive count, do not reserve anything here.
}
Payload::CustomSection(s)
if s.name() == "webidl-bindings" || s.name() == "wasm-interface-types" =>
{
bail!(
"\
Support for interface types has temporarily been removed from `wasmtime`.
For more information about this temporary change you can read on the issue online:
https://github.com/bytecodealliance/wasmtime/issues/1271
and for re-adding support for interface types you can see this issue:
https://github.com/bytecodealliance/wasmtime/issues/677
"
)
}
Payload::CustomSection(s) => {
self.register_custom_section(&s);
}
// It's expected that validation will probably reject other
// payloads such as `UnknownSection` or those related to the
// component model. If, however, something gets past validation then
// that's a bug in Wasmtime as we forgot to implement something.
other => {
self.validator.payload(&other)?;
panic!("unimplemented section in wasm file {other:?}");
}
}
Ok(())
}
fn register_custom_section(&mut self, section: &CustomSectionReader<'data>) {
match section.as_known() {
KnownCustom::Name(name) => {
let result = self.name_section(name);
if let Err(e) = result {
log::warn!("failed to parse name section {:?}", e);
}
}
_ => {
let name = section.name().trim_end_matches(".dwo");
if name.starts_with(".debug_") {
self.dwarf_section(name, section);
}
}
}
}
fn dwarf_section(&mut self, name: &str, section: &CustomSectionReader<'data>) {
if !self.tunables.generate_native_debuginfo && !self.tunables.parse_wasm_debuginfo {
self.result.has_unparsed_debuginfo = true;
return;
}
let info = &mut self.result.debuginfo;
let dwarf = &mut info.dwarf;
let endian = gimli::LittleEndian;
let data = section.data();
let slice = gimli::EndianSlice::new(data, endian);
match name {
// `gimli::Dwarf` fields.
".debug_abbrev" => dwarf.debug_abbrev = gimli::DebugAbbrev::new(data, endian),
".debug_addr" => dwarf.debug_addr = gimli::DebugAddr::from(slice),
".debug_info" => {
dwarf.debug_info = gimli::DebugInfo::new(data, endian);
}
".debug_line" => dwarf.debug_line = gimli::DebugLine::new(data, endian),
".debug_line_str" => dwarf.debug_line_str = gimli::DebugLineStr::from(slice),
".debug_str" => dwarf.debug_str = gimli::DebugStr::new(data, endian),
".debug_str_offsets" => dwarf.debug_str_offsets = gimli::DebugStrOffsets::from(slice),
".debug_str_sup" => {
let mut dwarf_sup: Dwarf<'data> = Default::default();
dwarf_sup.debug_str = gimli::DebugStr::from(slice);
dwarf.sup = Some(Arc::new(dwarf_sup));
}
".debug_types" => dwarf.debug_types = gimli::DebugTypes::from(slice),
// Additional fields.
".debug_loc" => info.debug_loc = gimli::DebugLoc::from(slice),
".debug_loclists" => info.debug_loclists = gimli::DebugLocLists::from(slice),
".debug_ranges" => info.debug_ranges = gimli::DebugRanges::new(data, endian),
".debug_rnglists" => info.debug_rnglists = gimli::DebugRngLists::new(data, endian),
// DWARF package fields
".debug_cu_index" => info.debug_cu_index = gimli::DebugCuIndex::new(data, endian),
".debug_tu_index" => info.debug_tu_index = gimli::DebugTuIndex::new(data, endian),
// We don't use these at the moment.
".debug_aranges" | ".debug_pubnames" | ".debug_pubtypes" => return,
other => {
log::warn!("unknown debug section `{}`", other);
return;
}
}
dwarf.ranges = gimli::RangeLists::new(info.debug_ranges, info.debug_rnglists);
dwarf.locations = gimli::LocationLists::new(info.debug_loc, info.debug_loclists);
}
/// Declares a new import with the `module` and `field` names, importing the
/// `ty` specified.
///
/// Note that this method is somewhat tricky due to the implementation of
/// the module linking proposal. In the module linking proposal two-level
/// imports are recast as single-level imports of instances. That recasting
/// happens here by recording an import of an instance for the first time
/// we see a two-level import.
///
/// When the module linking proposal is disabled, however, disregard this
/// logic and instead work directly with two-level imports since no
/// instances are defined.
fn declare_import(&mut self, module: &'data str, field: &'data str, ty: EntityType) {
let index = self.push_type(ty);
self.result.module.initializers.push(Initializer::Import {
name: module.to_owned(),
field: field.to_owned(),
index,
});
}
fn push_type(&mut self, ty: EntityType) -> EntityIndex {
match ty {
EntityType::Function(ty) => EntityIndex::Function({
let func_index = self
.result
.module
.push_function(ty.unwrap_module_type_index());
// Imported functions can escape; in fact, they've already done
// so to get here.
self.flag_func_escaped(func_index);
func_index
}),
EntityType::Table(ty) => EntityIndex::Table(self.result.module.tables.push(ty)),
EntityType::Memory(ty) => EntityIndex::Memory(self.result.module.memories.push(ty)),
EntityType::Global(ty) => EntityIndex::Global(self.result.module.globals.push(ty)),
EntityType::Tag(_) => unimplemented!(),
}
}
fn flag_func_escaped(&mut self, func: FuncIndex) {
let ty = &mut self.result.module.functions[func];
// If this was already assigned a funcref index no need to re-assign it.
if ty.is_escaping() {
return;
}
let index = self.result.module.num_escaped_funcs as u32;
ty.func_ref = FuncRefIndex::from_u32(index);
self.result.module.num_escaped_funcs += 1;
}
/// Parses the Name section of the wasm module.
fn name_section(&mut self, names: NameSectionReader<'data>) -> WasmResult<()> {
for subsection in names {
match subsection? {
wasmparser::Name::Function(names) => {
for name in names {
let Naming { index, name } = name?;
// Skip this naming if it's naming a function that
// doesn't actually exist.
if (index as usize) >= self.result.module.functions.len() {
continue;
}
// Store the name unconditionally, regardless of
// whether we're parsing debuginfo, since function
// names are almost always present in the
// final compilation artifact.
let index = FuncIndex::from_u32(index);
self.result
.debuginfo
.name_section
.func_names
.insert(index, name);
}
}
wasmparser::Name::Module { name, .. } => {
self.result.module.name = Some(name.to_string());
if self.tunables.generate_native_debuginfo {
self.result.debuginfo.name_section.module_name = Some(name);
}
}
wasmparser::Name::Local(reader) => {
if !self.tunables.generate_native_debuginfo {
continue;
}
for f in reader {
let f = f?;
// Skip this naming if it's naming a function that
// doesn't actually exist.
if (f.index as usize) >= self.result.module.functions.len() {
continue;
}
for name in f.names {
let Naming { index, name } = name?;
self.result
.debuginfo
.name_section
.locals_names
.entry(FuncIndex::from_u32(f.index))
.or_insert(HashMap::new())
.insert(index, name);
}
}
}
wasmparser::Name::Label(_)
| wasmparser::Name::Type(_)
| wasmparser::Name::Table(_)
| wasmparser::Name::Global(_)
| wasmparser::Name::Memory(_)
| wasmparser::Name::Element(_)
| wasmparser::Name::Data(_)
| wasmparser::Name::Tag(_)
| wasmparser::Name::Field(_)
| wasmparser::Name::Unknown { .. } => {}
}
}
Ok(())
}
}
impl TypeConvert for ModuleEnvironment<'_, '_> {
fn lookup_heap_type(&self, index: wasmparser::UnpackedIndex) -> WasmHeapType {
WasmparserTypeConverter::new(&self.types, |idx| self.result.module.types[idx])
.lookup_heap_type(index)
}
fn lookup_type_index(&self, index: wasmparser::UnpackedIndex) -> EngineOrModuleTypeIndex {
WasmparserTypeConverter::new(&self.types, |idx| self.result.module.types[idx])
.lookup_type_index(index)
}
}
impl ModuleTranslation<'_> {
/// Attempts to convert segmented memory initialization into static
/// initialization for the module that this translation represents.
///
/// If this module's memory initialization is not compatible with paged
/// initialization then this won't change anything. Otherwise if it is
/// compatible then the `memory_initialization` field will be updated.
///
/// Takes a `page_size` argument in order to ensure that all
/// initialization is page-aligned for mmap-ability, and
/// `max_image_size_always_allowed` to control how we decide
/// whether to use static init.
///
/// We will try to avoid generating very sparse images, which are
/// possible if e.g. a module has an initializer at offset 0 and a
/// very high offset (say, 1 GiB). To avoid this, we use a dual
/// condition: we always allow images less than
/// `max_image_size_always_allowed`, and the embedder of Wasmtime
/// can set this if desired to ensure that static init should
/// always be done if the size of the module or its heaps is
/// otherwise bounded by the system. We also allow images with
/// static init data bigger than that, but only if it is "dense",
/// defined as having at least half (50%) of its pages with some
/// data.
///
/// We could do something slightly better by building a dense part
/// and keeping a sparse list of outlier/leftover segments (see
/// issue #3820). This would also allow mostly-static init of
/// modules that have some dynamically-placed data segments. But,
/// for now, this is sufficient to allow a system that "knows what
/// it's doing" to always get static init.
pub fn try_static_init(&mut self, page_size: u64, max_image_size_always_allowed: u64) {
// This method only attempts to transform a `Segmented` memory init
// into a `Static` one, no other state.
if !self.module.memory_initialization.is_segmented() {
return;
}
// First a dry run of memory initialization is performed. This
// collects information about the extent of memory initialized for each
// memory as well as the size of all data segments being copied in.
struct Memory {
data_size: u64,
min_addr: u64,
max_addr: u64,
// The `usize` here is a pointer into `self.data` which is the list
// of data segments corresponding to what was found in the original
// wasm module.
segments: Vec<(usize, StaticMemoryInitializer)>,
}
let mut info = PrimaryMap::with_capacity(self.module.memories.len());
for _ in 0..self.module.memories.len() {
info.push(Memory {
data_size: 0,
min_addr: u64::MAX,
max_addr: 0,
segments: Vec::new(),
});
}
struct InitMemoryAtCompileTime<'a> {
module: &'a Module,
info: &'a mut PrimaryMap<MemoryIndex, Memory>,
idx: usize,
}
impl InitMemory for InitMemoryAtCompileTime<'_> {
fn memory_size_in_bytes(
&mut self,
memory_index: MemoryIndex,
) -> Result<u64, SizeOverflow> {
self.module.memories[memory_index].minimum_byte_size()
}
fn eval_offset(&mut self, memory_index: MemoryIndex, expr: &ConstExpr) -> Option<u64> {
match (expr.ops(), self.module.memories[memory_index].idx_type) {
(&[ConstOp::I32Const(offset)], IndexType::I32) => {
Some(offset.unsigned().into())
}
(&[ConstOp::I64Const(offset)], IndexType::I64) => Some(offset.unsigned()),
_ => None,
}
}
fn write(&mut self, memory: MemoryIndex, init: &StaticMemoryInitializer) -> bool {
// Currently `Static` only applies to locally-defined memories,
// so if a data segment references an imported memory then
// transitioning to a `Static` memory initializer is not
// possible.
if self.module.defined_memory_index(memory).is_none() {
return false;
};
let info = &mut self.info[memory];
let data_len = u64::from(init.data.end - init.data.start);
if data_len > 0 {
info.data_size += data_len;
info.min_addr = info.min_addr.min(init.offset);
info.max_addr = info.max_addr.max(init.offset + data_len);
info.segments.push((self.idx, init.clone()));
}
self.idx += 1;
true
}
}
let ok = self
.module
.memory_initialization
.init_memory(&mut InitMemoryAtCompileTime {
idx: 0,
module: &self.module,
info: &mut info,
});
if !ok {
return;
}
// Validate that the memory information collected is indeed valid for
// static memory initialization.
for (i, info) in info.iter().filter(|(_, info)| info.data_size > 0) {
let image_size = info.max_addr - info.min_addr;
// Simplify things for now by bailing out entirely if any memory has
// a page size smaller than the host's page size. This fixes a case
// where currently initializers are created in host-page-size units
// of length which means that a larger-than-the-entire-memory
// initializer can be created. This can be handled technically but
// would require some more changes to help fix the assert elsewhere
// that this protects against.
if self.module.memories[i].page_size() < page_size {
return;
}
// If the range of memory being initialized is less than twice the
// total size of the data itself then it's assumed that static
// initialization is ok. This means we'll at most double memory
// consumption during the memory image creation process, which is
// currently assumed to "probably be ok" but this will likely need
// tweaks over time.
if image_size < info.data_size.saturating_mul(2) {
continue;
}
// If the memory initialization image is larger than the size of all
// data, then we still allow memory initialization if the image will
// be of a relatively modest size, such as 1MB here.
if image_size < max_image_size_always_allowed {
continue;
}
// At this point memory initialization is concluded to be too
// expensive to do at compile time so it's entirely deferred to
// happen at runtime.
return;
}
// Here's where we've now committed to changing to static memory. The
// memory initialization image is built here from the page data and then
// it's converted to a single initializer.
let data = mem::replace(&mut self.data, Vec::new());
let mut map = PrimaryMap::with_capacity(info.len());
let mut module_data_size = 0u32;
for (memory, info) in info.iter() {
// Create the in-memory `image` which is the initialized contents of
// this linear memory.
let extent = if info.segments.len() > 0 {
(info.max_addr - info.min_addr) as usize
} else {
0
};
let mut image = Vec::with_capacity(extent);
for (idx, init) in info.segments.iter() {
let data = &data[*idx];
assert_eq!(data.len(), init.data.len());
let offset = usize::try_from(init.offset - info.min_addr).unwrap();
if image.len() < offset {
image.resize(offset, 0u8);
image.extend_from_slice(data);
} else {
image.splice(
offset..(offset + data.len()).min(image.len()),
data.iter().copied(),
);
}
}
assert_eq!(image.len(), extent);
assert_eq!(image.capacity(), extent);
let mut offset = if info.segments.len() > 0 {
info.min_addr
} else {
0
};
// Chop off trailing zeros from the image as memory is already
// zero-initialized. Note that `i` is the position of a nonzero
// entry here, so to not lose it we truncate to `i + 1`.
if let Some(i) = image.iter().rposition(|i| *i != 0) {
image.truncate(i + 1);
}
// Also chop off leading zeros, if any.
if let Some(i) = image.iter().position(|i| *i != 0) {
offset += i as u64;
image.drain(..i);
}
let mut len = u64::try_from(image.len()).unwrap();
// The goal is to enable mapping this image directly into memory, so
// the offset into linear memory must be a multiple of the page
// size. If that's not already the case then the image is padded at
// the front and back with extra zeros as necessary
if offset % page_size != 0 {
let zero_padding = offset % page_size;
self.data.push(vec![0; zero_padding as usize].into());
offset -= zero_padding;
len += zero_padding;
}
self.data.push(image.into());
if len % page_size != 0 {
let zero_padding = page_size - (len % page_size);
self.data.push(vec![0; zero_padding as usize].into());
len += zero_padding;
}
// Offset/length should now always be page-aligned.
assert!(offset % page_size == 0);
assert!(len % page_size == 0);
// Create the `StaticMemoryInitializer` which describes this image,
// only needed if the image is actually present and has a nonzero
// length. The `offset` has been calculates above, originally
// sourced from `info.min_addr`. The `data` field is the extent
// within the final data segment we'll emit to an ELF image, which
// is the concatenation of `self.data`, so here it's the size of
// the section-so-far plus the current segment we're appending.
let len = u32::try_from(len).unwrap();
let init = if len > 0 {
Some(StaticMemoryInitializer {
offset,
data: module_data_size..module_data_size + len,
})
} else {
None
};
let idx = map.push(init);
assert_eq!(idx, memory);
module_data_size += len;
}
self.data_align = Some(page_size);
self.module.memory_initialization = MemoryInitialization::Static { map };
}
/// Attempts to convert the module's table initializers to
/// FuncTable form where possible. This enables lazy table
/// initialization later by providing a one-to-one map of initial
/// table values, without having to parse all segments.
pub fn try_func_table_init(&mut self) {
// This should be large enough to support very large Wasm
// modules with huge funcref tables, but small enough to avoid
// OOMs or DoS on truly sparse tables.
const MAX_FUNC_TABLE_SIZE: u64 = 1024 * 1024;
// First convert any element-initialized tables to images of just that
// single function if the minimum size of the table allows doing so.
for ((_, init), (_, table)) in self
.module
.table_initialization
.initial_values
.iter_mut()
.zip(
self.module
.tables
.iter()
.skip(self.module.num_imported_tables),
)
{
let table_size = table.limits.min;
if table_size > MAX_FUNC_TABLE_SIZE {
continue;
}
if let TableInitialValue::Expr(expr) = init {
if let [ConstOp::RefFunc(f)] = expr.ops() {
*init = TableInitialValue::Null {
precomputed: vec![*f; table_size as usize],
};
}
}
}
let mut segments = mem::take(&mut self.module.table_initialization.segments)
.into_iter()
.peekable();
// The goal of this loop is to interpret a table segment and apply it
// "statically" to a local table. This will iterate over segments and
// apply them one-by-one to each table.
//
// If any segment can't be applied, however, then this loop exits and
// all remaining segments are placed back into the segment list. This is
// because segments are supposed to be initialized one-at-a-time which
// means that intermediate state is visible with respect to traps. If
// anything isn't statically known to not trap it's pessimistically
// assumed to trap meaning all further segment initializers must be
// applied manually at instantiation time.
while let Some(segment) = segments.peek() {
let defined_index = match self.module.defined_table_index(segment.table_index) {
Some(index) => index,
// Skip imported tables: we can't provide a preconstructed
// table for them, because their values depend on the
// imported table overlaid with whatever segments we have.
None => break,
};
// If the base of this segment is dynamic, then we can't
// include it in the statically-built array of initial
// contents.
let offset = match segment.offset.ops() {
&[ConstOp::I32Const(offset)] => u64::from(offset.unsigned()),
&[ConstOp::I64Const(offset)] => offset.unsigned(),
_ => break,
};
// Get the end of this segment. If out-of-bounds, or too
// large for our dense table representation, then skip the
// segment.
let top = match offset.checked_add(segment.elements.len()) {
Some(top) => top,
None => break,
};
let table_size = self.module.tables[segment.table_index].limits.min;
if top > table_size || top > MAX_FUNC_TABLE_SIZE {
break;
}
match self.module.tables[segment.table_index]
.ref_type
.heap_type
.top()
{
WasmHeapTopType::Func => {}
// If this is not a funcref table, then we can't support a
// pre-computed table of function indices. Technically this
// initializer won't trap so we could continue processing
// segments, but that's left as a future optimization if
// necessary.
WasmHeapTopType::Any | WasmHeapTopType::Extern => break,
}
// Function indices can be optimized here, but fully general
// expressions are deferred to get evaluated at runtime.
let function_elements = match &segment.elements {
TableSegmentElements::Functions(indices) => indices,
TableSegmentElements::Expressions(_) => break,
};
let precomputed =
match &mut self.module.table_initialization.initial_values[defined_index] {
TableInitialValue::Null { precomputed } => precomputed,
// If this table is still listed as an initial value here
// then that means the initial size of the table doesn't
// support a precomputed function list, so skip this.
// Technically this won't trap so it's possible to process
// further initializers, but that's left as a future
// optimization.
TableInitialValue::Expr(_) => break,
};
// At this point we're committing to pre-initializing the table
// with the `segment` that's being iterated over. This segment is
// applied to the `precomputed` list for the table by ensuring
// it's large enough to hold the segment and then copying the
// segment into the precomputed list.
if precomputed.len() < top as usize {
precomputed.resize(top as usize, FuncIndex::reserved_value());
}
let dst = &mut precomputed[offset as usize..top as usize];
dst.copy_from_slice(&function_elements);
// advance the iterator to see the next segment
let _ = segments.next();
}
self.module.table_initialization.segments = segments.collect();
}
}