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wasmtime: Implement global.{get,set} for externref globals (#1969)

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* wasmtime: Implement `global.{get,set}` for externref globals

We use libcalls to implement these -- unlike `table.{get,set}`, for which we
create inline JIT fast paths -- because no known toolchain actually uses
externref globals.

Part of #929

* wasmtime: Enable `{extern,func}ref` globals in the API
This commit is contained in:
Nick Fitzgerald
2020-07-02 14:04:01 -07:00
committed by GitHub
parent 3fa3ff2ece
commit bffd54c016
19 changed files with 520 additions and 79 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
crates/wasmtime/src/externals.rs
View File

@@ -7,6 +7,8 @@ use crate::{
ValType,
};
use anyhow::{anyhow, bail, Result};
use std::mem;
use std::ptr;
use std::slice;
use wasmtime_environ::wasm;
use wasmtime_runtime::{self as runtime, InstanceHandle};
@@ -227,6 +229,15 @@ impl Global {
ValType::I64 => Val::from(*definition.as_i64()),
ValType::F32 => Val::F32(*definition.as_u32()),
ValType::F64 => Val::F64(*definition.as_u64()),
ValType::ExternRef => Val::ExternRef(
definition
.as_externref()
.clone()
.map(|inner| ExternRef { inner }),
),
ValType::FuncRef => {
from_checked_anyfunc(definition.as_anyfunc() as *mut _, &self.instance.store)
}
ty => unimplemented!("Global::get for {:?}", ty),
}
}
@@ -256,6 +267,19 @@ impl Global {
Val::I64(i) => *definition.as_i64_mut() = i,
Val::F32(f) => *definition.as_u32_mut() = f,
Val::F64(f) => *definition.as_u64_mut() = f,
Val::FuncRef(f) => {
*definition.as_anyfunc_mut() = f.map_or(ptr::null(), |f| {
f.caller_checked_anyfunc().as_ptr() as *const _
});
}
Val::ExternRef(x) => {
// In case the old value's `Drop` implementation is
// re-entrant and tries to touch this global again, do a
// replace, and then drop. This way no one can observe a
// halfway-deinitialized value.
let old = mem::replace(definition.as_externref_mut(), x.map(|x| x.inner));
drop(old);
}
_ => unimplemented!("Global::set for {:?}", val.ty()),
}
}

14
crates/wasmtime/src/func.rs
View File

@@ -10,7 +10,8 @@ use std::panic::{self, AssertUnwindSafe};
use std::ptr::{self, NonNull};
use std::rc::Weak;
use wasmtime_runtime::{
raise_user_trap, Export, InstanceHandle, VMContext, VMFunctionBody, VMTrampoline,
raise_user_trap, Export, InstanceHandle, VMContext, VMFunctionBody, VMSharedSignatureIndex,
VMTrampoline,
};
/// A WebAssembly function which can be called.
@@ -494,19 +495,20 @@ impl Func {
func.into_func(store)
}
pub(crate) fn sig_index(&self) -> VMSharedSignatureIndex {
unsafe { self.export.anyfunc.as_ref().type_index }
}
/// Returns the underlying wasm type that this `Func` has.
pub fn ty(&self) -> FuncType {
// Signatures should always be registered in the store's registry of
// shared signatures, so we should be able to unwrap safely here.
let sig = self
.instance
.store
.lookup_signature(unsafe { self.export.anyfunc.as_ref().type_index });
let wft = self.instance.store.lookup_signature(self.sig_index());
// This is only called with `Export::Function`, and since it's coming
// from wasmtime_runtime itself we should support all the types coming
// out of it, so assert such here.
FuncType::from_wasm_func_type(&sig).expect("core wasm signature should be supported")
FuncType::from_wasm_func_type(&wft).expect("core wasm signature should be supported")
}
/// Returns the number of parameters that this function takes.

11
crates/wasmtime/src/runtime.rs
View File

@@ -900,6 +900,17 @@ impl Store {
.expect("failed to lookup signature")
}
pub(crate) fn lookup_wasm_and_native_signatures(
&self,
sig_index: VMSharedSignatureIndex,
) -> (wasm::WasmFuncType, ir::Signature) {
self.inner
.signatures
.borrow()
.lookup_wasm_and_native_signatures(sig_index)
.expect("failed to lookup signature")
}
pub(crate) fn register_signature(
&self,
wasm_sig: wasm::WasmFuncType,

7
crates/wasmtime/src/trampoline/create_handle.rs
View File

@@ -7,11 +7,11 @@ use std::any::Any;
use std::collections::HashMap;
use std::sync::Arc;
use wasmtime_environ::entity::PrimaryMap;
use wasmtime_environ::wasm::DefinedFuncIndex;
use wasmtime_environ::wasm::{DefinedFuncIndex, FuncIndex};
use wasmtime_environ::Module;
use wasmtime_runtime::{
Imports, InstanceHandle, StackMapRegistry, VMExternRefActivationsTable, VMFunctionBody,
VMSharedSignatureIndex, VMTrampoline,
VMFunctionImport, VMSharedSignatureIndex, VMTrampoline,
};
pub(crate) fn create_handle(
@@ -20,9 +20,10 @@ pub(crate) fn create_handle(
finished_functions: PrimaryMap<DefinedFuncIndex, *mut [VMFunctionBody]>,
trampolines: HashMap<VMSharedSignatureIndex, VMTrampoline>,
state: Box<dyn Any>,
func_imports: PrimaryMap<FuncIndex, VMFunctionImport>,
) -> Result<StoreInstanceHandle> {
let imports = Imports::new(
PrimaryMap::new(),
func_imports,
PrimaryMap::new(),
PrimaryMap::new(),
PrimaryMap::new(),

22
crates/wasmtime/src/trampoline/func.rs
View File

@@ -3,7 +3,7 @@
use super::create_handle::create_handle;
use crate::trampoline::StoreInstanceHandle;
use crate::{FuncType, Store, Trap};
use anyhow::{bail, Result};
use anyhow::Result;
use std::any::Any;
use std::cmp;
use std::collections::HashMap;
@@ -211,10 +211,7 @@ pub fn create_handle_with_function(
let isa = store.engine().config().target_isa();
let pointer_type = isa.pointer_type();
let sig = match ft.get_wasmtime_signature(pointer_type) {
Some(sig) => sig,
None => bail!("not a supported core wasm signature {:?}", ft),
};
let sig = ft.get_wasmtime_signature(pointer_type);
let mut fn_builder_ctx = FunctionBuilderContext::new();
let mut module = Module::new();
@@ -259,6 +256,7 @@ pub fn create_handle_with_function(
finished_functions,
trampolines,
Box::new(trampoline_state),
PrimaryMap::new(),
)
.map(|instance| (instance, trampoline))
}
@@ -277,10 +275,7 @@ pub unsafe fn create_handle_with_raw_function(
};
let pointer_type = isa.pointer_type();
let sig = match ft.get_wasmtime_signature(pointer_type) {
Some(sig) => sig,
None => bail!("not a supported core wasm signature {:?}", ft),
};
let sig = ft.get_wasmtime_signature(pointer_type);
let mut module = Module::new();
let mut finished_functions = PrimaryMap::new();
@@ -298,5 +293,12 @@ pub unsafe fn create_handle_with_raw_function(
let sig_id = store.register_signature(ft.to_wasm_func_type(), sig);
trampolines.insert(sig_id, trampoline);
create_handle(module, store, finished_functions, trampolines, state)
create_handle(
module,
store,
finished_functions,
trampolines,
state,
PrimaryMap::new(),
)
}

57
crates/wasmtime/src/trampoline/global.rs
View File

@@ -1,17 +1,19 @@
use super::create_handle::create_handle;
use crate::trampoline::StoreInstanceHandle;
use crate::{GlobalType, Mutability, Store, Val};
use anyhow::{bail, Result};
use anyhow::Result;
use wasmtime_environ::entity::PrimaryMap;
use wasmtime_environ::{wasm, EntityIndex, Module};
use wasmtime_runtime::VMFunctionImport;
pub fn create_global(store: &Store, gt: &GlobalType, val: Val) -> Result<StoreInstanceHandle> {
let mut module = Module::new();
let mut func_imports = PrimaryMap::new();
let mut externref_init = None;
let global = wasm::Global {
wasm_ty: gt.content().to_wasm_type(),
ty: match gt.content().get_wasmtime_type() {
Some(t) => t,
None => bail!("cannot support {:?} as a wasm global type", gt.content()),
},
ty: gt.content().get_wasmtime_type(),
mutability: match gt.mutability() {
Mutability::Const => false,
Mutability::Var => true,
@@ -21,10 +23,42 @@ pub fn create_global(store: &Store, gt: &GlobalType, val: Val) -> Result<StoreIn
Val::I64(i) => wasm::GlobalInit::I64Const(i),
Val::F32(f) => wasm::GlobalInit::F32Const(f),
Val::F64(f) => wasm::GlobalInit::F64Const(f),
Val::ExternRef(None) | Val::FuncRef(None) => wasm::GlobalInit::RefNullConst,
Val::ExternRef(Some(x)) => {
// There is no `GlobalInit` variant for using an existing
// `externref` that isn't an import (because Wasm can't create
// an `externref` by itself). Therefore, initialize the global
// as null, and then monkey patch it after instantiation below.
externref_init = Some(x);
wasm::GlobalInit::RefNullConst
}
Val::FuncRef(Some(f)) => {
// Add a function import to the stub module, and then initialize
// our global with a `ref.func` to grab that imported function.
let shared_sig_index = f.sig_index();
let local_sig_index = module
.local
.signatures
.push(store.lookup_wasm_and_native_signatures(shared_sig_index));
let func_index = module.local.functions.push(local_sig_index);
module.local.num_imported_funcs = 1;
module
.imports
.push(("".into(), "".into(), EntityIndex::Function(func_index)));
let f = f.caller_checked_anyfunc();
let f = unsafe { f.as_ref() };
func_imports.push(VMFunctionImport {
body: f.func_ptr,
vmctx: f.vmctx,
});
wasm::GlobalInit::RefFunc(func_index)
}
_ => unimplemented!("create_global for {:?}", gt),
},
};
let mut module = Module::new();
let global_id = module.local.globals.push(global);
module
.exports
@@ -35,6 +69,17 @@ pub fn create_global(store: &Store, gt: &GlobalType, val: Val) -> Result<StoreIn
PrimaryMap::new(),
Default::default(),
Box::new(()),
func_imports,
)?;
if let Some(x) = externref_init {
match handle.lookup("global").unwrap() {
wasmtime_runtime::Export::Global(g) => unsafe {
*(*g.definition).as_externref_mut() = Some(x.inner);
},
_ => unreachable!(),
}
}
Ok(handle)
}

1
crates/wasmtime/src/trampoline/memory.rs
View File

@@ -35,6 +35,7 @@ pub fn create_handle_with_memory(
PrimaryMap::new(),
Default::default(),
Box::new(()),
PrimaryMap::new(),
)
}

1
crates/wasmtime/src/trampoline/table.rs
View File

@@ -32,5 +32,6 @@ pub fn create_handle_with_table(store: &Store, table: &TableType) -> Result<Stor
PrimaryMap::new(),
Default::default(),
Box::new(()),
PrimaryMap::new(),
)
}

34
crates/wasmtime/src/types.rs
View File

@@ -99,15 +99,15 @@ impl ValType {
}
}
pub(crate) fn get_wasmtime_type(&self) -> Option<ir::Type> {
pub(crate) fn get_wasmtime_type(&self) -> ir::Type {
match self {
ValType::I32 => Some(ir::types::I32),
ValType::I64 => Some(ir::types::I64),
ValType::F32 => Some(ir::types::F32),
ValType::F64 => Some(ir::types::F64),
ValType::V128 => Some(ir::types::I8X16),
ValType::ExternRef => Some(wasmtime_runtime::ref_type()),
_ => None,
ValType::I32 => ir::types::I32,
ValType::I64 => ir::types::I64,
ValType::F32 => ir::types::F32,
ValType::F64 => ir::types::F64,
ValType::V128 => ir::types::I8X16,
ValType::ExternRef => wasmtime_runtime::ref_type(),
ValType::FuncRef => wasmtime_runtime::pointer_type(),
}
}
@@ -248,34 +248,32 @@ impl FuncType {
}
}
/// Returns `Some` if this function signature was compatible with cranelift,
/// or `None` if one of the types/results wasn't supported or compatible
/// with cranelift.
pub(crate) fn get_wasmtime_signature(&self, pointer_type: ir::Type) -> Option<ir::Signature> {
/// Get the Cranelift-compatible function signature.
pub(crate) fn get_wasmtime_signature(&self, pointer_type: ir::Type) -> ir::Signature {
use wasmtime_environ::ir::{AbiParam, ArgumentPurpose, Signature};
use wasmtime_jit::native;
let call_conv = native::call_conv();
let mut params = self
.params
.iter()
.map(|p| p.get_wasmtime_type().map(AbiParam::new))
.collect::<Option<Vec<_>>>()?;
.map(|p| AbiParam::new(p.get_wasmtime_type()))
.collect::<Vec<_>>();
let returns = self
.results
.iter()
.map(|p| p.get_wasmtime_type().map(AbiParam::new))
.collect::<Option<Vec<_>>>()?;
.map(|p| AbiParam::new(p.get_wasmtime_type()))
.collect::<Vec<_>>();
params.insert(
0,
AbiParam::special(pointer_type, ArgumentPurpose::VMContext),
);
params.insert(1, AbiParam::new(pointer_type));
Some(Signature {
Signature {
params,
returns,
call_conv,
})
}
}
/// Returns `None` if any types in the signature can't be converted to the