145 lines
4.6 KiB
Rust
145 lines
4.6 KiB
Rust
//! A `Compilation` contains the compiled function bodies for a WebAssembly
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//! module.
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use cranelift_codegen::binemit;
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use cranelift_codegen::ir;
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use cranelift_codegen::ir::ExternalName;
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use cranelift_codegen::isa;
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use cranelift_codegen::Context;
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use cranelift_entity::{EntityRef, PrimaryMap};
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use cranelift_wasm::{DefinedFuncIndex, FuncIndex, FuncTranslator};
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use environ::{get_func_name, ModuleTranslation};
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use std::string::{String, ToString};
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use std::vec::Vec;
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/// The result of compiling a WebAssemby module's functions.
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#[derive(Debug)]
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pub struct Compilation {
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/// Compiled machine code for the function bodies.
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pub functions: PrimaryMap<DefinedFuncIndex, Vec<u8>>,
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}
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impl Compilation {
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/// Allocates the compilation result with the given function bodies.
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pub fn new(functions: PrimaryMap<DefinedFuncIndex, Vec<u8>>) -> Self {
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Self { functions }
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}
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}
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/// Implementation of a relocation sink that just saves all the information for later
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pub struct RelocSink {
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/// Relocations recorded for the function.
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pub func_relocs: Vec<Relocation>,
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}
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impl binemit::RelocSink for RelocSink {
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fn reloc_ebb(
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&mut self,
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_offset: binemit::CodeOffset,
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_reloc: binemit::Reloc,
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_ebb_offset: binemit::CodeOffset,
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) {
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// This should use the `offsets` field of `ir::Function`.
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panic!("ebb headers not yet implemented");
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}
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fn reloc_external(
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&mut self,
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offset: binemit::CodeOffset,
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reloc: binemit::Reloc,
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name: &ExternalName,
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addend: binemit::Addend,
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) {
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let reloc_target = if let ExternalName::User { namespace, index } = *name {
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debug_assert!(namespace == 0);
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RelocationTarget::UserFunc(FuncIndex::new(index as usize))
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} else if *name == ExternalName::testcase("grow_memory") {
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RelocationTarget::GrowMemory
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} else if *name == ExternalName::testcase("current_memory") {
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RelocationTarget::CurrentMemory
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} else {
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panic!("unrecognized external name")
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};
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self.func_relocs.push(Relocation {
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reloc,
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reloc_target,
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offset,
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addend,
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});
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}
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fn reloc_jt(
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&mut self,
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_offset: binemit::CodeOffset,
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_reloc: binemit::Reloc,
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_jt: ir::JumpTable,
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) {
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panic!("jump tables not yet implemented");
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}
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}
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impl RelocSink {
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fn new() -> Self {
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Self {
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func_relocs: Vec::new(),
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}
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}
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}
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/// A record of a relocation to perform.
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#[derive(Debug, Clone)]
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pub struct Relocation {
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/// The relocation code.
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pub reloc: binemit::Reloc,
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/// Relocation target.
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pub reloc_target: RelocationTarget,
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/// The offset where to apply the relocation.
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pub offset: binemit::CodeOffset,
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/// The addend to add to the relocation value.
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pub addend: binemit::Addend,
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}
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/// Destination function. Can be either user function or some special one, like grow_memory.
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#[derive(Debug, Copy, Clone)]
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pub enum RelocationTarget {
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/// The user function index.
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UserFunc(FuncIndex),
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/// Function for growing the default memory by the specified amount of pages.
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GrowMemory,
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/// Function for query current size of the default linear memory.
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CurrentMemory,
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}
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/// Relocations to apply to function bodies.
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pub type Relocations = PrimaryMap<DefinedFuncIndex, Vec<Relocation>>;
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/// Compile the module, producing a compilation result with associated
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/// relocations.
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pub fn compile_module<'data, 'module>(
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translation: &ModuleTranslation<'data, 'module>,
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isa: &isa::TargetIsa,
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) -> Result<(Compilation, Relocations), String> {
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let mut functions = PrimaryMap::new();
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let mut relocations = PrimaryMap::new();
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for (i, input) in translation.lazy.function_body_inputs.iter() {
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let func_index = translation.module.func_index(i);
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let mut context = Context::new();
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context.func.name = get_func_name(func_index);
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context.func.signature =
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translation.module.signatures[translation.module.functions[func_index]].clone();
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let mut trans = FuncTranslator::new();
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trans
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.translate(input, &mut context.func, &mut translation.func_env())
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.map_err(|e| e.to_string())?;
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let mut code_buf: Vec<u8> = Vec::new();
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let mut reloc_sink = RelocSink::new();
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let mut trap_sink = binemit::NullTrapSink {};
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context
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.compile_and_emit(isa, &mut code_buf, &mut reloc_sink, &mut trap_sink)
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.map_err(|e| e.to_string())?;
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functions.push(code_buf);
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relocations.push(reloc_sink.func_relocs);
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}
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Ok((Compilation::new(functions), relocations))
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}
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