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wasmtime: add build-time option for parallel compilation (#1903)
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When running in embedded environments, threads creation is sometimes
undesirable. This adds a feature to toggle wasmtime's internal thread
creation for parallel compilation.
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@ueno
ueno authored Jul 6, 2020
1 parent 80ff22f commit 2ce2dd0
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Showing 6 changed files with 149 additions and 123 deletions.
1 change: 1 addition & 0 deletions Cargo.lock
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2 changes: 1 addition & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,7 @@ members = [
]

[features]
default = ["jitdump", "wasmtime/wat"]
default = ["jitdump", "wasmtime/wat", "wasmtime/parallel-compilation"]
lightbeam = [
"wasmtime-environ/lightbeam",
"wasmtime-jit/lightbeam",
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6 changes: 5 additions & 1 deletion crates/environ/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ cranelift-wasm = { path = "../../cranelift/wasm", version = "0.65.0", features =
wasmparser = "0.58.0"
lightbeam = { path = "../lightbeam", optional = true, version = "0.18.0" }
indexmap = "1.0.2"
rayon = "1.2.1"
rayon = { version = "1.2.1", optional = true }
thiserror = "1.0.4"
directories = "2.0.1"
sha2 = "0.8.0"
Expand All @@ -32,6 +32,7 @@ zstd = "0.5"
toml = "0.5.5"
file-per-thread-logger = "0.1.1"
more-asserts = "0.2.1"
cfg-if = "0.1.9"

[target.'cfg(target_os = "windows")'.dependencies]
winapi = "0.3.7"
Expand All @@ -46,5 +47,8 @@ pretty_env_logger = "0.4.0"
filetime = "0.2.7"
lazy_static = "1.3.0"

[features]
parallel-compilation = ["rayon"]

[badges]
maintenance = { status = "actively-developed" }
256 changes: 137 additions & 119 deletions crates/environ/src/cranelift.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,7 @@ use cranelift_codegen::print_errors::pretty_error;
use cranelift_codegen::{binemit, isa, Context};
use cranelift_entity::PrimaryMap;
use cranelift_wasm::{DefinedFuncIndex, FuncIndex, FuncTranslator, ModuleTranslationState};
#[cfg(feature = "parallel-compilation")]
use rayon::prelude::{IntoParallelRefIterator, ParallelIterator};
use std::convert::TryFrom;
use std::hash::{Hash, Hasher};
Expand Down Expand Up @@ -318,132 +319,149 @@ fn compile(env: CompileEnv<'_>) -> Result<ModuleCacheDataTupleType, CompileError
let mut traps = PrimaryMap::with_capacity(env.function_body_inputs.len());
let mut stack_maps = PrimaryMap::with_capacity(env.function_body_inputs.len());

env.function_body_inputs
.into_iter()
.collect::<Vec<(DefinedFuncIndex, &FunctionBodyData<'_>)>>()
.par_iter()
.map_init(FuncTranslator::new, |func_translator, (i, input)| {
let func_index = env.local.func_index(*i);
let mut context = Context::new();
context.func.name = get_func_name(func_index);
context.func.signature = env.local.native_func_signature(func_index).clone();
if env.tunables.debug_info {
context.func.collect_debug_info();
}
type FunctionBodyInput<'a> = (DefinedFuncIndex, &'a FunctionBodyData<'a>);

let mut func_env = FuncEnvironment::new(isa.frontend_config(), env.local, env.tunables);

// We use these as constant offsets below in
// `stack_limit_from_arguments`, so assert their values here. This
// allows the closure below to get coerced to a function pointer, as
// needed by `ir::Function`.
//
// Otherwise our stack limit is specially calculated from the vmctx
// argument, where we need to load the `*const VMInterrupts`
// pointer, and then from that pointer we need to load the stack
// limit itself. Note that manual register allocation is needed here
// too due to how late in the process this codegen happens.
//
// For more information about interrupts and stack checks, see the
// top of this file.
let vmctx = context
.func
.create_global_value(ir::GlobalValueData::VMContext);
let interrupts_ptr = context.func.create_global_value(ir::GlobalValueData::Load {
base: vmctx,
offset: i32::try_from(func_env.offsets.vmctx_interrupts())
.unwrap()
.into(),
global_type: isa.pointer_type(),
readonly: true,
});
let stack_limit = context.func.create_global_value(ir::GlobalValueData::Load {
base: interrupts_ptr,
offset: i32::try_from(func_env.offsets.vminterrupts_stack_limit())
.unwrap()
.into(),
global_type: isa.pointer_type(),
readonly: false,
});
context.func.stack_limit = Some(stack_limit);
func_translator.translate(
env.module_translation.0,
input.data,
input.module_offset,
&mut context.func,
&mut func_env,
)?;

let mut code_buf: Vec<u8> = Vec::new();
let mut reloc_sink = RelocSink::new(func_index);
let mut trap_sink = TrapSink::new();
let mut stack_map_sink = StackMapSink::default();
context
.compile_and_emit(
isa,
&mut code_buf,
&mut reloc_sink,
&mut trap_sink,
&mut stack_map_sink,
)
.map_err(|error| {
CompileError::Codegen(pretty_error(&context.func, Some(isa), error))
})?;

let unwind_info = context.create_unwind_info(isa).map_err(|error| {
let compile_function = |func_translator: &mut FuncTranslator,
(i, input): &FunctionBodyInput| {
let func_index = env.local.func_index(*i);
let mut context = Context::new();
context.func.name = get_func_name(func_index);
context.func.signature = env.local.native_func_signature(func_index).clone();
if env.tunables.debug_info {
context.func.collect_debug_info();
}

let mut func_env = FuncEnvironment::new(isa.frontend_config(), env.local, env.tunables);

// We use these as constant offsets below in
// `stack_limit_from_arguments`, so assert their values here. This
// allows the closure below to get coerced to a function pointer, as
// needed by `ir::Function`.
//
// Otherwise our stack limit is specially calculated from the vmctx
// argument, where we need to load the `*const VMInterrupts`
// pointer, and then from that pointer we need to load the stack
// limit itself. Note that manual register allocation is needed here
// too due to how late in the process this codegen happens.
//
// For more information about interrupts and stack checks, see the
// top of this file.
let vmctx = context
.func
.create_global_value(ir::GlobalValueData::VMContext);
let interrupts_ptr = context.func.create_global_value(ir::GlobalValueData::Load {
base: vmctx,
offset: i32::try_from(func_env.offsets.vmctx_interrupts())
.unwrap()
.into(),
global_type: isa.pointer_type(),
readonly: true,
});
let stack_limit = context.func.create_global_value(ir::GlobalValueData::Load {
base: interrupts_ptr,
offset: i32::try_from(func_env.offsets.vminterrupts_stack_limit())
.unwrap()
.into(),
global_type: isa.pointer_type(),
readonly: false,
});
context.func.stack_limit = Some(stack_limit);
func_translator.translate(
env.module_translation.0,
input.data,
input.module_offset,
&mut context.func,
&mut func_env,
)?;

let mut code_buf: Vec<u8> = Vec::new();
let mut reloc_sink = RelocSink::new(func_index);
let mut trap_sink = TrapSink::new();
let mut stack_map_sink = StackMapSink::default();
context
.compile_and_emit(
isa,
&mut code_buf,
&mut reloc_sink,
&mut trap_sink,
&mut stack_map_sink,
)
.map_err(|error| {
CompileError::Codegen(pretty_error(&context.func, Some(isa), error))
})?;

let address_transform = get_function_address_map(&context, input, code_buf.len(), isa);
let unwind_info = context.create_unwind_info(isa).map_err(|error| {
CompileError::Codegen(pretty_error(&context.func, Some(isa), error))
})?;

let address_transform = get_function_address_map(&context, input, code_buf.len(), isa);

let ranges = if env.tunables.debug_info {
let ranges = context.build_value_labels_ranges(isa).map_err(|error| {
CompileError::Codegen(pretty_error(&context.func, Some(isa), error))
})?;
Some(ranges)
} else {
None
};

let ranges = if env.tunables.debug_info {
let ranges = context.build_value_labels_ranges(isa).map_err(|error| {
CompileError::Codegen(pretty_error(&context.func, Some(isa), error))
})?;
Some(ranges)
Ok((
code_buf,
context.func.jt_offsets,
reloc_sink.func_relocs,
address_transform,
ranges,
context.func.stack_slots,
trap_sink.traps,
unwind_info,
stack_map_sink.finish(),
))
};

let inputs: Vec<FunctionBodyInput> = env.function_body_inputs.into_iter().collect();

let results: Result<Vec<_>, CompileError> = {
cfg_if::cfg_if! {
if #[cfg(feature = "parallel-compilation")] {
inputs
.par_iter()
.map_init(FuncTranslator::new, compile_function)
.collect()
} else {
None
};

Ok((
code_buf,
context.func.jt_offsets,
reloc_sink.func_relocs,
address_transform,
ranges,
context.func.stack_slots,
trap_sink.traps,
unwind_info,
stack_map_sink.finish(),
))
})
.collect::<Result<Vec<_>, CompileError>>()?
.into_iter()
.for_each(
|(
function,
func_jt_offsets,
relocs,
address_transform,
ranges,
sss,
function_traps,
let mut func_translator = FuncTranslator::new();
inputs
.iter()
.map(|input| compile_function(&mut func_translator, input))
.collect()
}
}
};

results?.into_iter().for_each(
|(
function,
func_jt_offsets,
relocs,
address_transform,
ranges,
sss,
function_traps,
unwind_info,
stack_map,
)| {
functions.push(CompiledFunction {
body: function,
jt_offsets: func_jt_offsets,
unwind_info,
stack_map,
)| {
functions.push(CompiledFunction {
body: function,
jt_offsets: func_jt_offsets,
unwind_info,
});
relocations.push(relocs);
address_transforms.push(address_transform);
value_ranges.push(ranges.unwrap_or_default());
stack_slots.push(sss);
traps.push(function_traps);
stack_maps.push(stack_map);
},
);
});
relocations.push(relocs);
address_transforms.push(address_transform);
value_ranges.push(ranges.unwrap_or_default());
stack_slots.push(sss);
traps.push(function_traps);
stack_maps.push(stack_map);
},
);

// TODO: Reorganize where we create the Vec for the resolved imports.

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5 changes: 4 additions & 1 deletion crates/wasmtime/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,7 @@ wasmtime-wasi = { path = "../wasi" }
maintenance = { status = "actively-developed" }

[features]
default = ['wat', 'jitdump']
default = ['wat', 'jitdump', 'parallel-compilation']

# Enables experimental support for the lightbeam codegen backend, an alternative
# to cranelift. Requires Nightly Rust currently, and this is not enabled by
Expand All @@ -50,3 +50,6 @@ jitdump = ["wasmtime-jit/jitdump"]

# Enables support for the `VTune` profiler
vtune = ["wasmtime-jit/vtune"]

# Enables parallel compilation of WebAssembly code
parallel-compilation = ["wasmtime-environ/parallel-compilation"]
2 changes: 1 addition & 1 deletion crates/wiggle/wasmtime/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
include = ["src/**/*", "LICENSE"]

[dependencies]
wasmtime = { path = "../../wasmtime", version = "0.18.0" }
wasmtime = { path = "../../wasmtime", version = "0.18.0", default-features = false }
wasmtime-wiggle-macro = { path = "./macro", version = "0.18.0" }
witx = { path = "../../wasi-common/WASI/tools/witx", version = "0.8.5", optional = true }
wiggle = { path = "..", version = "0.18.0" }
Expand Down

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