Files
wasmtime/lib/wasm/src/module_translator.rs
2017-09-11 18:01:50 -07:00

244 lines
11 KiB
Rust

//! Translation skeletton that traverses the whole WebAssembly module and call helper functions
//! to deal with each part of it.
use wasmparser::{ParserState, SectionCode, ParserInput, Parser, WasmDecoder, BinaryReaderError};
use sections_translator::{SectionParsingError, parse_function_signatures, parse_import_section,
parse_function_section, parse_export_section, parse_memory_section,
parse_global_section, parse_table_section, parse_elements_section,
parse_data_section};
use translation_utils::{Import, SignatureIndex, FunctionIndex};
use cretonne::ir::{Function, FunctionName};
use func_translator::FuncTranslator;
use std::collections::HashMap;
use std::error::Error;
use runtime::WasmRuntime;
/// Output of the [`translate_module`](fn.translate_module.html) function.
pub struct TranslationResult {
/// The translated functions.
pub functions: Vec<Function>,
/// When present, the index of the function defined as `start` of the module.
///
/// Note that this is a WebAssembly function index and not an index into the `functions` vector
/// above. The imported functions are numbered before the local functions.
pub start_index: Option<FunctionIndex>,
}
/// Translate a sequence of bytes forming a valid Wasm binary into a list of valid Cretonne IL
/// [`Function`](../cretonne/ir/function/struct.Function.html).
/// Returns the functions and also the mappings for imported functions and signature between the
/// indexes in the wasm module and the indexes inside each functions.
pub fn translate_module(
data: &[u8],
runtime: &mut WasmRuntime,
) -> Result<TranslationResult, String> {
let mut parser = Parser::new(data);
match *parser.read() {
ParserState::BeginWasm { .. } => {}
ParserState::Error(BinaryReaderError { message, offset }) => {
return Err(format!("at offset {}: {}", offset, message));
}
ref s => panic!("modules should begin properly: {:?}", s),
}
let mut signatures = None;
let mut functions: Option<Vec<SignatureIndex>> = None;
let mut globals = Vec::new();
let mut exports: Option<HashMap<FunctionIndex, String>> = None;
let mut next_input = ParserInput::Default;
let mut function_index: FunctionIndex = 0;
let mut start_index: Option<FunctionIndex> = None;
loop {
match *parser.read_with_input(next_input) {
ParserState::BeginSection { code: SectionCode::Type, .. } => {
match parse_function_signatures(&mut parser, runtime) {
Ok(sigs) => signatures = Some(sigs),
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the type section: {}", s))
}
};
next_input = ParserInput::Default;
}
ParserState::BeginSection { code: SectionCode::Import, .. } => {
match parse_import_section(&mut parser, runtime) {
Ok(imps) => {
for import in imps {
match import {
Import::Function { sig_index } => {
functions = match functions {
None => Some(vec![sig_index as SignatureIndex]),
Some(mut funcs) => {
funcs.push(sig_index as SignatureIndex);
Some(funcs)
}
};
function_index += 1;
}
Import::Memory(mem) => {
runtime.declare_memory(mem);
}
Import::Global(glob) => {
runtime.declare_global(glob);
globals.push(glob);
}
Import::Table(tab) => {
runtime.declare_table(tab);
}
}
}
}
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the import section: {}", s))
}
}
next_input = ParserInput::Default;
}
ParserState::BeginSection { code: SectionCode::Function, .. } => {
match parse_function_section(&mut parser, runtime) {
Ok(funcs) => {
match functions {
None => functions = Some(funcs),
Some(ref mut imps) => imps.extend(funcs),
}
}
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the function section: {}", s))
}
}
next_input = ParserInput::Default;
}
ParserState::BeginSection { code: SectionCode::Table, .. } => {
match parse_table_section(&mut parser, runtime) {
Ok(()) => (),
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the table section: {}", s))
}
}
}
ParserState::BeginSection { code: SectionCode::Memory, .. } => {
match parse_memory_section(&mut parser) {
Ok(mems) => {
for mem in mems {
runtime.declare_memory(mem);
}
}
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the memory section: {}", s))
}
}
next_input = ParserInput::Default;
}
ParserState::BeginSection { code: SectionCode::Global, .. } => {
match parse_global_section(&mut parser, runtime) {
Ok(mut globs) => globals.append(&mut globs),
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the global section: {}", s))
}
}
next_input = ParserInput::Default;
}
ParserState::BeginSection { code: SectionCode::Export, .. } => {
match parse_export_section(&mut parser) {
Ok(exps) => exports = Some(exps),
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the export section: {}", s))
}
}
next_input = ParserInput::Default;
}
ParserState::BeginSection { code: SectionCode::Start, .. } => {
match *parser.read() {
ParserState::StartSectionEntry(index) => {
start_index = Some(index as FunctionIndex)
}
_ => return Err(String::from("wrong content in the start section")),
}
match *parser.read() {
ParserState::EndSection => {}
_ => return Err(String::from("wrong content in the start section")),
}
next_input = ParserInput::Default;
}
ParserState::BeginSection { code: SectionCode::Element, .. } => {
match parse_elements_section(&mut parser, runtime, &globals) {
Ok(()) => (),
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the element section: {}", s))
}
}
next_input = ParserInput::Default;
}
ParserState::BeginSection { code: SectionCode::Code, .. } => {
// The code section begins
break;
}
ParserState::EndSection => {
next_input = ParserInput::Default;
}
ParserState::EndWasm => {
return Ok(TranslationResult {
functions: Vec::new(),
start_index: None,
})
}
ParserState::BeginSection { code: SectionCode::Data, .. } => {
match parse_data_section(&mut parser, runtime, &globals) {
Ok(()) => (),
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the data section: {}", s))
}
}
}
_ => return Err(String::from("wrong content in the preamble")),
};
}
// At this point we've entered the code section
// First we check that we have all that is necessary to translate a function.
let signatures = signatures.unwrap_or_default();
let functions = match functions {
None => return Err(String::from("missing a function section")),
Some(functions) => functions,
};
let mut il_functions: Vec<Function> = Vec::new();
let mut trans = FuncTranslator::new();
runtime.begin_translation();
loop {
match *parser.read() {
ParserState::BeginFunctionBody { .. } => {}
ParserState::EndSection => break,
_ => return Err(String::from("wrong content in code section")),
}
runtime.next_function();
// First we build the Function object with its name and signature
let mut func = Function::new();
func.signature = signatures[functions[function_index]].clone();
if let Some(ref exports) = exports {
if let Some(name) = exports.get(&function_index) {
func.name = FunctionName::new(name.clone());
}
}
trans
.translate_from_reader(parser.create_binary_reader(), &mut func, runtime)
.map_err(|e| String::from(e.description()))?;
il_functions.push(func);
function_index += 1;
}
loop {
match *parser.read() {
ParserState::BeginSection { code: SectionCode::Data, .. } => {
match parse_data_section(&mut parser, runtime, &globals) {
Ok(()) => (),
Err(SectionParsingError::WrongSectionContent(s)) => {
return Err(format!("wrong content in the data section: {}", s))
}
}
}
ParserState::EndWasm => {
return Ok(TranslationResult {
functions: il_functions,
start_index,
})
}
_ => (),
}
}
}