change Module::define_function to take TrapSink instances
Experience with the `define_function` API has shown that returning borrowed slices of `TrapSite` is not ideal: the returned slice represents a borrow on the entire `Module`, which makes calling back into methods taking `&mut self` a bit tricky. To eliminate the problem, let's require the callers of `define_function` to provide `TrapSink` instances. This style of API enables them to control when and how traps are collected, and makes the `object` and `faerie` backends simpler/more efficient by not having to worry about trap collection.
This commit is contained in:
Nathan Froyd
@@ -1,15 +1,14 @@
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//! Defines `ObjectBackend`.
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use crate::traps::ObjectTrapSink;
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use cranelift_codegen::binemit::{
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Addend, CodeOffset, NullStackmapSink, NullTrapSink, Reloc, RelocSink,
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Addend, CodeOffset, NullStackmapSink, Reloc, RelocSink, TrapSink,
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};
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use cranelift_codegen::entity::SecondaryMap;
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use cranelift_codegen::isa::TargetIsa;
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use cranelift_codegen::{self, binemit, ir};
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use cranelift_module::{
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Backend, DataContext, DataDescription, DataId, FuncId, Init, Linkage, ModuleNamespace,
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ModuleResult, TrapSite,
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ModuleResult,
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};
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use object::write::{
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Object, Relocation, SectionId, StandardSection, Symbol, SymbolId, SymbolSection,
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@@ -17,24 +16,12 @@ use object::write::{
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use object::{RelocationEncoding, RelocationKind, SymbolFlags, SymbolKind, SymbolScope};
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use std::collections::HashMap;
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use std::mem;
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use std::ops::IndexMut;
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use target_lexicon::{BinaryFormat, PointerWidth};
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#[derive(Debug)]
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/// Setting to enable collection of traps. Setting this to `Enabled` in
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/// `ObjectBuilder` means that `ObjectProduct` will contains trap sites.
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pub enum ObjectTrapCollection {
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/// `ObjectProduct::traps` will be empty
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Disabled,
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/// `ObjectProduct::traps` will contain trap sites
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Enabled,
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}
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/// A builder for `ObjectBackend`.
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pub struct ObjectBuilder {
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isa: Box<dyn TargetIsa>,
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name: Vec<u8>,
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collect_traps: ObjectTrapCollection,
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libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
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function_alignment: u64,
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}
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@@ -43,9 +30,6 @@ impl ObjectBuilder {
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/// Create a new `ObjectBuilder` using the given Cranelift target, that
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/// can be passed to [`Module::new`](cranelift_module::Module::new).
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///
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/// `collect_traps` setting determines whether trap information is collected in the
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/// `ObjectProduct`.
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///
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/// The `libcall_names` function provides a way to translate `cranelift_codegen`'s `ir::LibCall`
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/// enum to symbols. LibCalls are inserted in the IR as part of the legalization for certain
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/// floating point instructions, and for stack probes. If you don't know what to use for this
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@@ -53,13 +37,11 @@ impl ObjectBuilder {
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pub fn new<V: Into<Vec<u8>>>(
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isa: Box<dyn TargetIsa>,
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name: V,
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collect_traps: ObjectTrapCollection,
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libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
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) -> Self {
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Self {
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isa,
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name: name.into(),
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collect_traps,
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libcall_names,
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function_alignment: 1,
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}
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@@ -80,11 +62,9 @@ pub struct ObjectBackend {
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object: Object,
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functions: SecondaryMap<FuncId, Option<SymbolId>>,
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data_objects: SecondaryMap<DataId, Option<SymbolId>>,
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traps: SecondaryMap<FuncId, Vec<TrapSite>>,
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relocs: Vec<SymbolRelocs>,
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libcalls: HashMap<ir::LibCall, SymbolId>,
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libcall_names: Box<dyn Fn(ir::LibCall) -> String>,
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collect_traps: ObjectTrapCollection,
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function_alignment: u64,
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}
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@@ -111,11 +91,9 @@ impl Backend for ObjectBackend {
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object,
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functions: SecondaryMap::new(),
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data_objects: SecondaryMap::new(),
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traps: SecondaryMap::new(),
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relocs: Vec::new(),
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libcalls: HashMap::new(),
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libcall_names: builder.libcall_names,
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collect_traps: builder.collect_traps,
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function_alignment: builder.function_alignment,
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}
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}
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@@ -182,41 +160,31 @@ impl Backend for ObjectBackend {
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}
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}
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fn define_function(
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fn define_function<TS>(
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&mut self,
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func_id: FuncId,
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_name: &str,
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ctx: &cranelift_codegen::Context,
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_namespace: &ModuleNamespace<Self>,
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code_size: u32,
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) -> ModuleResult<(ObjectCompiledFunction, &[TrapSite])> {
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trap_sink: &mut TS,
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) -> ModuleResult<ObjectCompiledFunction>
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where
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TS: TrapSink,
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{
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let mut code: Vec<u8> = vec![0; code_size as usize];
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let mut reloc_sink = ObjectRelocSink::new(self.object.format());
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let mut trap_sink = ObjectTrapSink::default();
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let mut stackmap_sink = NullStackmapSink {};
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if let ObjectTrapCollection::Enabled = self.collect_traps {
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unsafe {
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ctx.emit_to_memory(
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&*self.isa,
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code.as_mut_ptr(),
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&mut reloc_sink,
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&mut trap_sink,
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&mut stackmap_sink,
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)
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};
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} else {
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let mut trap_sink = NullTrapSink {};
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unsafe {
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ctx.emit_to_memory(
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&*self.isa,
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code.as_mut_ptr(),
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&mut reloc_sink,
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&mut trap_sink,
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&mut stackmap_sink,
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)
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};
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}
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unsafe {
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ctx.emit_to_memory(
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&*self.isa,
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code.as_mut_ptr(),
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&mut reloc_sink,
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trap_sink,
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&mut stackmap_sink,
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)
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};
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let symbol = self.functions[func_id].unwrap();
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let section = self.object.section_id(StandardSection::Text);
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@@ -230,9 +198,7 @@ impl Backend for ObjectBackend {
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relocs: reloc_sink.relocs,
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});
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}
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let trapref = self.traps.index_mut(func_id);
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*trapref = trap_sink.sites;
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Ok((ObjectCompiledFunction, trapref))
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Ok(ObjectCompiledFunction)
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}
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fn define_function_bytes(
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@@ -241,16 +207,13 @@ impl Backend for ObjectBackend {
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_name: &str,
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bytes: &[u8],
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_namespace: &ModuleNamespace<Self>,
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traps: Vec<TrapSite>,
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) -> ModuleResult<(ObjectCompiledFunction, &[TrapSite])> {
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) -> ModuleResult<ObjectCompiledFunction> {
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let symbol = self.functions[func_id].unwrap();
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let section = self.object.section_id(StandardSection::Text);
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let _offset = self
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.object
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.add_symbol_data(symbol, section, bytes, self.function_alignment);
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let trapref = self.traps.index_mut(func_id);
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*trapref = traps;
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Ok((ObjectCompiledFunction, trapref))
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Ok(ObjectCompiledFunction)
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}
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fn define_data(
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@@ -421,7 +384,6 @@ impl Backend for ObjectBackend {
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object: self.object,
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functions: self.functions,
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data_objects: self.data_objects,
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traps: self.traps,
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}
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}
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}
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@@ -496,8 +458,6 @@ pub struct ObjectProduct {
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pub functions: SecondaryMap<FuncId, Option<SymbolId>>,
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/// Symbol IDs for data objects (both declared and defined).
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pub data_objects: SecondaryMap<DataId, Option<SymbolId>>,
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/// Trap sites for defined functions.
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pub traps: SecondaryMap<FuncId, Vec<TrapSite>>,
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}
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impl ObjectProduct {
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