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Refactor store frame information.

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This commit refactors the store frame information to eliminate the copying of
data out from `CompiledModule`.

It also moves the population of a `BTreeMap` out of the frame information and
into `CompiledModule` where it is only ever calculated once rather than at
every new module instantiation into a `Store`. The map is also lazy-initialized
so the cost of populating the map is incurred only when a trap occurs.

This should help improve instantiation time of modules with a large number of
functions and functions with lots of instructions.
This commit is contained in:
Peter Huene
2021-04-07 00:46:57 -07:00
parent 6b77786a6e
commit 875cb92cf0
6 changed files with 218 additions and 191 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
Cargo.lock generated
View File

@@ -3407,6 +3407,7 @@ dependencies = [
"log",
"more-asserts",
"object",
"once_cell",
"rayon",
"region",
"serde",

1
crates/jit/Cargo.toml
View File

@@ -37,6 +37,7 @@ gimli = { version = "0.23.0", default-features = false, features = ["write"] }
object = { version = "0.23.0", default-features = false, features = ["write"] }
serde = { version = "1.0.94", features = ["derive"] }
addr2line = { version = "0.14", default-features = false }
once_cell = "1.7.2"
[target.'cfg(target_os = "windows")'.dependencies]
winapi = { version = "0.3.8", features = ["winnt", "impl-default"] }

69
crates/jit/src/instantiate.rs
View File

@@ -8,9 +8,11 @@ use crate::compiler::{Compilation, Compiler};
use crate::link::link_module;
use crate::object::ObjectUnwindInfo;
use object::File as ObjectFile;
use once_cell::sync::OnceCell;
#[cfg(feature = "parallel-compilation")]
use rayon::prelude::*;
use serde::{Deserialize, Serialize};
use std::collections::BTreeMap;
use std::ops::Range;
use std::sync::Arc;
use thiserror::Error;
@@ -195,17 +197,26 @@ pub struct TypeTables {
/// Container for data needed for an Instance function to exist.
pub struct ModuleCode {
range: (usize, usize),
code_memory: CodeMemory,
#[allow(dead_code)]
dbg_jit_registration: Option<GdbJitImageRegistration>,
}
impl ModuleCode {
/// Gets the [begin, end) range of the module's code.
pub fn range(&self) -> (usize, usize) {
self.range
}
}
/// A compiled wasm module, ready to be instantiated.
pub struct CompiledModule {
artifacts: CompilationArtifacts,
code: Arc<ModuleCode>,
finished_functions: FinishedFunctions,
trampolines: Vec<(SignatureIndex, VMTrampoline)>,
func_map: OnceCell<BTreeMap<usize, (usize, DefinedFuncIndex)>>,
}
impl CompiledModule {
@@ -259,15 +270,19 @@ impl CompiledModule {
};
let finished_functions = FinishedFunctions(finished_functions);
let start = code_range.0 as usize;
let end = start + code_range.1;
Ok(Arc::new(Self {
artifacts,
code: Arc::new(ModuleCode {
range: (start, end),
code_memory,
dbg_jit_registration,
}),
finished_functions,
trampolines,
func_map: Default::default(),
}))
}
@@ -312,25 +327,45 @@ impl CompiledModule {
)
}
/// Iterates over all functions in this module, returning information about
/// how to decode traps which happen in the function.
pub fn trap_information(
&self,
) -> impl Iterator<
Item = (
DefinedFuncIndex,
*mut [VMFunctionBody],
&[TrapInformation],
&FunctionAddressMap,
),
> {
self.finished_functions()
.iter()
.zip(self.artifacts.funcs.values())
.map(|((i, alloc), func)| (i, *alloc, func.traps.as_slice(), &func.address_map))
/// Gets the function map of the compiled module.
///
/// The map is from ending address (inclusive) to a tuple of starting address and
/// defined function index.
///
/// The map is lazily-initialized, so it will be populated the first time this
/// method is called.
pub fn func_map(&self) -> &BTreeMap<usize, (usize, DefinedFuncIndex)> {
self.func_map.get_or_init(|| {
let mut functions = BTreeMap::new();
for (index, allocated) in self.finished_functions().iter() {
let (start, end) = unsafe {
let ptr = (**allocated).as_ptr();
let len = (**allocated).len();
// First and last byte of the function text.
(ptr as usize, ptr as usize + len - 1)
};
// Finished functions cannot be empty
assert!(start <= end);
assert!(functions.insert(end, (start, index)).is_none());
}
functions
})
}
/// Returns all ranges convered by JIT code.
/// Gets the function information for a given function index.
pub fn func_info(
&self,
index: DefinedFuncIndex,
) -> Option<(&FunctionAddressMap, &[TrapInformation])> {
self.artifacts
.funcs
.get(index)
.map(|f| (&f.address_map, f.traps.as_ref()))
}
/// Returns all ranges covered by JIT code.
pub fn jit_code_ranges<'a>(&'a self) -> impl Iterator<Item = (usize, usize)> + 'a {
self.code.code_memory.published_ranges()
}

323
crates/wasmtime/src/frame_info.rs
View File

@@ -1,16 +1,14 @@
use std::cmp;
use std::collections::BTreeMap;
use std::sync::Arc;
use std::sync::Mutex;
use wasmtime_environ::entity::EntityRef;
use wasmtime_environ::ir;
use wasmtime_environ::wasm::FuncIndex;
use wasmtime_environ::{FunctionAddressMap, Module, TrapInformation};
use wasmtime_jit::{CompiledModule, SymbolizeContext};
use wasmtime_environ::wasm::DefinedFuncIndex;
use wasmtime_environ::{FunctionAddressMap, TrapInformation};
use wasmtime_jit::CompiledModule;
/// This is a structure that lives within a `Store` and retains information
/// about all wasm code registered with the `Store` (e.g. modules that have
/// been instantiated into a store).
/// about all modules registered with the `Store` via instantiation.
///
/// "frame information" here refers to things like determining whether a
/// program counter is a wasm program counter, and additionally mapping program
@@ -31,25 +29,6 @@ pub struct StoreFrameInfo {
ranges: BTreeMap<usize, ModuleFrameInfo>,
}
/// This is a listing of information for each module registered with a store
/// which lives in `StoreFrameInfo`.
struct ModuleFrameInfo {
start: usize,
functions: Arc<BTreeMap<usize, FunctionInfo>>,
module: Arc<Module>,
symbolize: Option<SymbolizeContext>,
has_unparsed_debuginfo: bool,
}
/// Information about a function, specifically information about individual
/// traps and such.
struct FunctionInfo {
start: usize,
index: FuncIndex,
traps: Vec<TrapInformation>,
instr_map: FunctionAddressMap,
}
impl StoreFrameInfo {
/// Fetches frame information about a program counter in a backtrace.
///
@@ -58,8 +37,103 @@ impl StoreFrameInfo {
/// returned indicates whether the original module has unparsed debug
/// information due to the compiler's configuration.
pub fn lookup_frame_info(&self, pc: usize) -> Option<(FrameInfo, bool)> {
let (module, func) = self.func(pc)?;
let pos = func.instr_pos(pc);
let module = self.module(pc)?;
module
.lookup_frame_info(pc)
.map(|info| (info, module.has_unparsed_debuginfo()))
}
/// Returns whether the `pc` specified is contained within some module's
/// function.
pub fn contains_pc(&self, pc: usize) -> bool {
match self.module(pc) {
Some(module) => module.contains_pc(pc),
None => false,
}
}
/// Fetches trap information about a program counter in a backtrace.
pub fn lookup_trap_info(&self, pc: usize) -> Option<&TrapInformation> {
self.module(pc)?.lookup_trap_info(pc)
}
fn module(&self, pc: usize) -> Option<&ModuleFrameInfo> {
let (end, info) = self.ranges.range(pc..).next()?;
if pc < info.start || *end < pc {
return None;
}
Some(info)
}
/// Registers a new compiled module's frame information.
pub fn register(&mut self, module: &Arc<CompiledModule>) {
let (start, end) = module.code().range();
// Ignore modules with no code or finished functions
if start == end || module.finished_functions().is_empty() {
return;
}
// The module code range is exclusive for end, so make it inclusive as it
// may be a valid PC value
let end = end - 1;
if self.contains_pc(start) {
return;
}
// Assert that this module's code doesn't collide with any other registered modules
if let Some((_, prev)) = self.ranges.range(end..).next() {
assert!(prev.start > end);
}
if let Some((prev_end, _)) = self.ranges.range(..=start).next_back() {
assert!(*prev_end < start);
}
let prev = self.ranges.insert(
end,
ModuleFrameInfo {
start,
module: module.clone(),
},
);
assert!(prev.is_none());
GLOBAL_INFO.lock().unwrap().register(start, end, module);
}
}
impl Drop for StoreFrameInfo {
fn drop(&mut self) {
let mut info = GLOBAL_INFO.lock().unwrap();
for end in self.ranges.keys() {
info.unregister(*end);
}
}
}
/// Represents a module's frame information.
#[derive(Clone)]
pub struct ModuleFrameInfo {
start: usize,
module: Arc<CompiledModule>,
}
impl ModuleFrameInfo {
/// Determines if the related module has unparsed debug information.
pub fn has_unparsed_debuginfo(&self) -> bool {
self.module.has_unparsed_debuginfo()
}
/// Fetches frame information about a program counter in a backtrace.
///
/// Returns an object if this `pc` is known to this module, or returns `None`
/// if no information can be found.
pub fn lookup_frame_info(&self, pc: usize) -> Option<FrameInfo> {
let (index, offset) = self.func(pc)?;
let (addr_map, _) = self.module.func_info(index)?;
let pos = Self::instr_pos(offset, addr_map);
// In debug mode for now assert that we found a mapping for `pc` within
// the function, because otherwise something is buggy along the way and
@@ -68,8 +142,8 @@ impl StoreFrameInfo {
debug_assert!(pos.is_some(), "failed to find instruction for {:x}", pc);
let instr = match pos {
Some(pos) => func.instr_map.instructions[pos].srcloc,
None => func.instr_map.start_srcloc,
Some(pos) => addr_map.instructions[pos].srcloc,
None => addr_map.start_srcloc,
};
// Use our wasm-relative pc to symbolize this frame. If there's a
@@ -81,7 +155,8 @@ impl StoreFrameInfo {
// here for now since technically wasm modules can always have any
// custom section contents.
let mut symbols = Vec::new();
if let Some(s) = &module.symbolize {
if let Some(s) = &self.module.symbolize_context().ok().and_then(|c| c) {
let to_lookup = (instr.bits() as u64) - s.code_section_offset();
if let Ok(mut frames) = s.addr2line().find_frames(to_lookup) {
while let Ok(Some(frame)) = frames.next() {
@@ -103,20 +178,20 @@ impl StoreFrameInfo {
}
}
Some((
FrameInfo {
module_name: module.module.name.clone(),
func_index: func.index.index() as u32,
func_name: module.module.func_names.get(&func.index).cloned(),
instr,
func_start: func.instr_map.start_srcloc,
symbols,
},
module.has_unparsed_debuginfo,
))
let module = self.module.module();
let index = module.func_index(index);
Some(FrameInfo {
module_name: module.name.clone(),
func_index: index.index() as u32,
func_name: module.func_names.get(&index).cloned(),
instr,
func_start: addr_map.start_srcloc,
symbols,
})
}
/// Returns whether the `pc` specified is contaained within some module's
/// Returns whether the `pc` specified is contained within some module's
/// function.
pub fn contains_pc(&self, pc: usize) -> bool {
self.func(pc).is_some()
@@ -124,89 +199,31 @@ impl StoreFrameInfo {
/// Fetches trap information about a program counter in a backtrace.
pub fn lookup_trap_info(&self, pc: usize) -> Option<&TrapInformation> {
let (_module, func) = self.func(pc)?;
let idx = func
.traps
.binary_search_by_key(&((pc - func.start) as u32), |info| info.code_offset)
let (index, offset) = self.func(pc)?;
let (_, traps) = self.module.func_info(index)?;
let idx = traps
.binary_search_by_key(&offset, |info| info.code_offset)
.ok()?;
Some(&func.traps[idx])
Some(&traps[idx])
}
fn func(&self, pc: usize) -> Option<(&ModuleFrameInfo, &FunctionInfo)> {
func(pc, &self.ranges, |t| (t.start, &t.functions))
fn func(&self, pc: usize) -> Option<(DefinedFuncIndex, u32)> {
let (end, (start, index)) = self.module.func_map().range(pc..).next()?;
if pc < *start || *end < pc {
return None;
}
Some((*index, (pc - *start) as u32))
}
/// Registers a new compiled module's frame information.
///
/// This function will register the `names` information for all of the
/// compiled functions within `module`. If the `module` has no functions
/// then `None` will be returned. Otherwise the returned object, when
/// dropped, will be used to unregister all name information from this map.
pub fn register(&mut self, module: &CompiledModule) {
let mut min = usize::max_value();
let mut max = 0;
let mut functions = BTreeMap::new();
for (i, allocated, traps, address_map) in module.trap_information() {
let (start, end) = unsafe {
let ptr = (*allocated).as_ptr();
let len = (*allocated).len();
// First and last byte of the function text.
(ptr as usize, ptr as usize + len - 1)
};
// Skip empty functions.
if end < start {
continue;
}
min = cmp::min(min, start);
max = cmp::max(max, end);
let func = FunctionInfo {
start,
index: module.module().func_index(i),
traps: traps.to_vec(),
instr_map: address_map.clone(),
};
assert!(functions.insert(end, func).is_none());
}
if functions.len() == 0 {
return;
}
let functions = Arc::new(functions);
// First up assert that our chunk of jit functions doesn't collide with
// any other known chunks of jit functions...
if let Some((_, prev)) = self.ranges.range(max..).next() {
assert!(prev.start > max);
}
if let Some((prev_end, _)) = self.ranges.range(..=min).next_back() {
assert!(*prev_end < min);
}
// ... then insert our range and assert nothing was there previously
GLOBAL_INFO.lock().unwrap().register(min, max, &functions);
let prev = self.ranges.insert(
max,
ModuleFrameInfo {
start: min,
functions,
module: module.module().clone(),
symbolize: module.symbolize_context().ok().and_then(|c| c),
has_unparsed_debuginfo: module.has_unparsed_debuginfo(),
},
);
assert!(prev.is_none());
}
}
impl FunctionInfo {
fn instr_pos(&self, pc: usize) -> Option<usize> {
fn instr_pos(offset: u32, addr_map: &FunctionAddressMap) -> Option<usize> {
// Use our relative position from the start of the function to find the
// machine instruction that corresponds to `pc`, which then allows us to
// map that to a wasm original source location.
let rel_pos = (pc - self.start) as u32;
match self
.instr_map
match addr_map
.instructions
.binary_search_by_key(&rel_pos, |map| map.code_offset)
.binary_search_by_key(&offset, |map| map.code_offset)
{
// Exact hit!
Ok(pos) => Some(pos),
@@ -221,15 +238,6 @@ impl FunctionInfo {
}
}
impl Drop for StoreFrameInfo {
fn drop(&mut self) {
let mut info = GLOBAL_INFO.lock().unwrap();
for end in self.ranges.keys() {
info.unregister(*end);
}
}
}
/// This is the dual of `StoreFrameInfo` and is stored globally (as the name
/// implies) rather than simply in one `Store`.
///
@@ -244,16 +252,14 @@ impl Drop for StoreFrameInfo {
/// information. When a `StoreFrameInfo` is destroyed then all of its entries
/// are removed from the global frame information.
#[derive(Default)]
pub(crate) struct GlobalFrameInfo {
pub struct GlobalFrameInfo {
// The map here behaves the same way as `StoreFrameInfo`.
ranges: BTreeMap<usize, GlobalModuleFrameInfo>,
}
/// This is the equivalent of `ModuleFrameInfo` except has less code and is
/// stored within `GlobalFrameInfo`.
/// This is the equivalent of `ModuleFrameInfo` except it keeps a reference count.
struct GlobalModuleFrameInfo {
start: usize,
functions: Arc<BTreeMap<usize, FunctionInfo>>,
module: ModuleFrameInfo,
/// Note that modules can be instantiated in many stores, so the purpose of
/// this field is to keep track of how many stores have registered a
@@ -271,64 +277,57 @@ impl GlobalFrameInfo {
/// is a wasm trap or not.
pub(crate) fn is_wasm_pc(pc: usize) -> bool {
let info = GLOBAL_INFO.lock().unwrap();
match func(pc, &info.ranges, |i| (i.start, &i.functions)) {
Some((_, info)) => info.instr_pos(pc).is_some(),
match info.ranges.range(pc..).next() {
Some((end, info)) => {
if pc < info.module.start || *end < pc {
return false;
}
match info.module.func(pc) {
Some((index, offset)) => {
let (addr_map, _) = info.module.module.func_info(index).unwrap();
ModuleFrameInfo::instr_pos(offset, addr_map).is_some()
}
None => false,
}
}
None => false,
}
}
/// Registers a new region of code, described by `(start, end)` and with
/// the given function information, with the global information.
fn register(
&mut self,
start: usize,
end: usize,
functions: &Arc<BTreeMap<usize, FunctionInfo>>,
) {
fn register(&mut self, start: usize, end: usize, module: &Arc<CompiledModule>) {
let info = self
.ranges
.entry(end)
.or_insert_with(|| GlobalModuleFrameInfo {
start,
functions: functions.clone(),
module: ModuleFrameInfo {
start,
module: module.clone(),
},
references: 0,
});
// Note that ideally we'd debug_assert that the information previously
// stored, if any, matches the `functions` we were given, but for now we
// just do some simple checks to hope it's the same.
assert_eq!(info.start, start);
assert_eq!(info.functions.len(), functions.len());
assert_eq!(info.module.start, start);
info.references += 1;
}
/// Unregisters a region of code (keyed by the `end` address) from this
/// global information.
fn unregister(&mut self, end: usize) {
let val = self.ranges.get_mut(&end).unwrap();
val.references -= 1;
if val.references == 0 {
let info = self.ranges.get_mut(&end).unwrap();
info.references -= 1;
if info.references == 0 {
self.ranges.remove(&end);
}
}
}
fn func<T>(
pc: usize,
ranges: &BTreeMap<usize, T>,
get_start_and_functions: impl FnOnce(&T) -> (usize, &BTreeMap<usize, FunctionInfo>),
) -> Option<(&T, &FunctionInfo)> {
let (end, info) = ranges.range(pc..).next()?;
let (start, functions) = get_start_and_functions(info);
if pc < start || *end < pc {
return None;
}
let (end, func) = functions.range(pc..).next()?;
if pc < func.start || *end < pc {
return None;
}
Some((info, func))
}
/// Description of a frame in a backtrace for a [`Trap`].
///
/// Whenever a WebAssembly trap occurs an instance of [`Trap`] is created. Each

2
crates/wasmtime/src/module.rs
View File

@@ -436,7 +436,7 @@ impl Module {
}
}
pub(crate) fn compiled_module(&self) -> &CompiledModule {
pub(crate) fn compiled_module(&self) -> &Arc<CompiledModule> {
&self.inner.module
}

13
crates/wasmtime/src/store.rs
View File

@@ -294,17 +294,8 @@ impl Store {
.insert(ArcModuleCode(module.compiled_module().code().clone()));
}
fn register_jit_code(&self, module: &CompiledModule) {
let functions = module.finished_functions();
let first_pc = match functions.values().next() {
Some(f) => unsafe { (**f).as_ptr() as usize },
None => return,
};
// Only register this module if it hasn't already been registered.
let mut info = self.inner.frame_info.borrow_mut();
if !info.contains_pc(first_pc) {
info.register(module);
}
fn register_jit_code(&self, module: &Arc<CompiledModule>) {
self.inner.frame_info.borrow_mut().register(module)
}
fn register_stack_maps(&self, module: &CompiledModule) {