Refactor unwind generation in Cranelift.
This commit makes the following changes to unwind information generation in Cranelift: * Remove frame layout change implementation in favor of processing the prologue and epilogue instructions when unwind information is requested. This also means this work is no longer performed for Windows, which didn't utilize it. It also helps simplify the prologue and epilogue generation code. * Remove the unwind sink implementation that required each unwind information to be represented in final form. For FDEs, this meant writing a complete frame table per function, which wastes 20 bytes or so for each function with duplicate CIEs. This also enables Cranelift users to collect the unwind information and write it as a single frame table. * For System V calling convention, the unwind information is no longer stored in code memory (it's only a requirement for Windows ABI to do so). This allows for more compact code memory for modules with a lot of functions. * Deletes some duplicate code relating to frame table generation. Users can now simply use gimli to create a frame table from each function's unwind information. Fixes #1181.
This commit is contained in:
Peter Huene
@@ -4,138 +4,13 @@
|
||||
use crate::cache::ModuleCacheDataTupleType;
|
||||
use crate::CacheConfig;
|
||||
use crate::ModuleTranslation;
|
||||
use cranelift_codegen::{binemit, ir, isa, CodegenResult, Context};
|
||||
use cranelift_codegen::{binemit, ir, isa, isa::unwind::UnwindInfo};
|
||||
use cranelift_entity::PrimaryMap;
|
||||
use cranelift_wasm::{DefinedFuncIndex, FuncIndex, WasmError};
|
||||
use serde::{Deserialize, Serialize};
|
||||
use std::ops::Range;
|
||||
use thiserror::Error;
|
||||
|
||||
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
|
||||
pub struct FDERelocEntry(pub i64, pub usize, pub u8);
|
||||
|
||||
/// Relocation entry for unwind info.
|
||||
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
|
||||
pub struct CompiledFunctionUnwindInfoReloc {
|
||||
/// Entry offest in the code block.
|
||||
pub offset: u32,
|
||||
/// Entry addend relative to the code block.
|
||||
pub addend: u32,
|
||||
}
|
||||
|
||||
/// Compiled function unwind information.
|
||||
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
|
||||
pub enum CompiledFunctionUnwindInfo {
|
||||
/// No info.
|
||||
None,
|
||||
/// Windows UNWIND_INFO.
|
||||
Windows(Vec<u8>),
|
||||
/// Frame layout info.
|
||||
FrameLayout(Vec<u8>, usize, Vec<FDERelocEntry>),
|
||||
}
|
||||
|
||||
impl CompiledFunctionUnwindInfo {
|
||||
/// Constructs unwind info object.
|
||||
pub fn new(isa: &dyn isa::TargetIsa, context: &Context) -> CodegenResult<Self> {
|
||||
use cranelift_codegen::binemit::{
|
||||
FrameUnwindKind, FrameUnwindOffset, FrameUnwindSink, Reloc,
|
||||
};
|
||||
use cranelift_codegen::isa::CallConv;
|
||||
|
||||
struct Sink(Vec<u8>, usize, Vec<FDERelocEntry>);
|
||||
impl FrameUnwindSink for Sink {
|
||||
fn len(&self) -> FrameUnwindOffset {
|
||||
self.0.len()
|
||||
}
|
||||
fn bytes(&mut self, b: &[u8]) {
|
||||
self.0.extend_from_slice(b);
|
||||
}
|
||||
fn reserve(&mut self, len: usize) {
|
||||
self.0.reserve(len)
|
||||
}
|
||||
fn reloc(&mut self, r: Reloc, off: FrameUnwindOffset) {
|
||||
self.2.push(FDERelocEntry(
|
||||
0,
|
||||
off,
|
||||
match r {
|
||||
Reloc::Abs4 => 4,
|
||||
Reloc::Abs8 => 8,
|
||||
_ => {
|
||||
panic!("unexpected reloc type");
|
||||
}
|
||||
},
|
||||
))
|
||||
}
|
||||
fn set_entry_offset(&mut self, off: FrameUnwindOffset) {
|
||||
self.1 = off;
|
||||
}
|
||||
}
|
||||
|
||||
let kind = match context.func.signature.call_conv {
|
||||
CallConv::SystemV | CallConv::Fast | CallConv::Cold => FrameUnwindKind::Libunwind,
|
||||
CallConv::WindowsFastcall => FrameUnwindKind::Fastcall,
|
||||
_ => {
|
||||
return Ok(CompiledFunctionUnwindInfo::None);
|
||||
}
|
||||
};
|
||||
|
||||
let mut sink = Sink(Vec::new(), 0, Vec::new());
|
||||
context.emit_unwind_info(isa, kind, &mut sink)?;
|
||||
|
||||
let Sink(data, offset, relocs) = sink;
|
||||
if data.is_empty() {
|
||||
return Ok(CompiledFunctionUnwindInfo::None);
|
||||
}
|
||||
|
||||
let info = match kind {
|
||||
FrameUnwindKind::Fastcall => CompiledFunctionUnwindInfo::Windows(data),
|
||||
FrameUnwindKind::Libunwind => {
|
||||
CompiledFunctionUnwindInfo::FrameLayout(data, offset, relocs)
|
||||
}
|
||||
};
|
||||
|
||||
Ok(info)
|
||||
}
|
||||
|
||||
/// Retuns true is no unwind info data.
|
||||
pub fn is_empty(&self) -> bool {
|
||||
match self {
|
||||
CompiledFunctionUnwindInfo::None => true,
|
||||
CompiledFunctionUnwindInfo::Windows(d) => d.is_empty(),
|
||||
CompiledFunctionUnwindInfo::FrameLayout(c, _, _) => c.is_empty(),
|
||||
}
|
||||
}
|
||||
|
||||
/// Returns size of serilized unwind info.
|
||||
pub fn len(&self) -> usize {
|
||||
match self {
|
||||
CompiledFunctionUnwindInfo::None => 0,
|
||||
CompiledFunctionUnwindInfo::Windows(d) => d.len(),
|
||||
CompiledFunctionUnwindInfo::FrameLayout(c, _, _) => c.len(),
|
||||
}
|
||||
}
|
||||
|
||||
/// Serializes data into byte array.
|
||||
pub fn serialize(&self, dest: &mut [u8], relocs: &mut Vec<CompiledFunctionUnwindInfoReloc>) {
|
||||
match self {
|
||||
CompiledFunctionUnwindInfo::None => (),
|
||||
CompiledFunctionUnwindInfo::Windows(d) => {
|
||||
dest.copy_from_slice(d);
|
||||
}
|
||||
CompiledFunctionUnwindInfo::FrameLayout(code, _fde_offset, r) => {
|
||||
dest.copy_from_slice(code);
|
||||
r.iter().for_each(move |r| {
|
||||
assert_eq!(r.2, 8);
|
||||
relocs.push(CompiledFunctionUnwindInfoReloc {
|
||||
offset: r.1 as u32,
|
||||
addend: r.0 as u32,
|
||||
})
|
||||
});
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Compiled function: machine code body, jump table offsets, and unwind information.
|
||||
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
|
||||
pub struct CompiledFunction {
|
||||
@@ -146,7 +21,7 @@ pub struct CompiledFunction {
|
||||
pub jt_offsets: ir::JumpTableOffsets,
|
||||
|
||||
/// The unwind information.
|
||||
pub unwind_info: CompiledFunctionUnwindInfo,
|
||||
pub unwind_info: Option<UnwindInfo>,
|
||||
}
|
||||
|
||||
type Functions = PrimaryMap<DefinedFuncIndex, CompiledFunction>;
|
||||
@@ -167,15 +42,15 @@ impl Compilation {
|
||||
/// Allocates the compilation result with the given function bodies.
|
||||
pub fn from_buffer(
|
||||
buffer: Vec<u8>,
|
||||
functions: impl IntoIterator<Item = (Range<usize>, ir::JumpTableOffsets, Range<usize>)>,
|
||||
functions: impl IntoIterator<Item = (Range<usize>, ir::JumpTableOffsets)>,
|
||||
) -> Self {
|
||||
Self::new(
|
||||
functions
|
||||
.into_iter()
|
||||
.map(|(body_range, jt_offsets, unwind_range)| CompiledFunction {
|
||||
.map(|(body_range, jt_offsets)| CompiledFunction {
|
||||
body: buffer[body_range].to_vec(),
|
||||
jt_offsets,
|
||||
unwind_info: CompiledFunctionUnwindInfo::Windows(buffer[unwind_range].to_vec()),
|
||||
unwind_info: None, // not implemented for lightbeam currently
|
||||
})
|
||||
.collect(),
|
||||
)
|
||||
|
||||
Reference in New Issue
Block a user