use super::create_handle::create_handle;
use crate::trampoline::StoreInstanceHandle;
use crate::{FuncType, Store, Trap};
use anyhow::Result;
use std::any::Any;
use std::cmp;
use std::mem;
use std::panic::{self, AssertUnwindSafe};
use wasmtime_environ::entity::PrimaryMap;
use wasmtime_environ::isa::TargetIsa;
use wasmtime_environ::wasm::SignatureIndex;
use wasmtime_environ::{ir, wasm, CompiledFunction, Module, ModuleType};
use wasmtime_jit::trampoline::ir::{
ExternalName, Function, InstBuilder, MemFlags, StackSlotData, StackSlotKind,
};
use wasmtime_jit::trampoline::{
self, binemit, pretty_error, Context, FunctionBuilder, FunctionBuilderContext,
};
use wasmtime_jit::CodeMemory;
use wasmtime_runtime::{InstanceHandle, VMContext, VMFunctionBody, VMTrampoline};
struct TrampolineState {
func: Box<dyn Fn(*mut VMContext, *mut u128) -> Result<(), Trap>>,
#[allow(dead_code)]
code_memory: CodeMemory,
}
unsafe extern "C" fn stub_fn(
vmctx: *mut VMContext,
caller_vmctx: *mut VMContext,
values_vec: *mut u128,
) {
let result = panic::catch_unwind(AssertUnwindSafe(|| {
call_stub(vmctx, caller_vmctx, values_vec)
}));
match result {
Ok(Ok(())) => {}
Ok(Err(trap)) => wasmtime_runtime::raise_user_trap(Box::new(trap)),
Err(panic) => wasmtime_runtime::resume_panic(panic),
}
unsafe fn call_stub(
vmctx: *mut VMContext,
caller_vmctx: *mut VMContext,
values_vec: *mut u128,
) -> Result<(), Trap> {
let instance = InstanceHandle::from_vmctx(vmctx);
let state = &instance
.host_state()
.downcast_ref::<TrampolineState>()
.expect("state");
(state.func)(caller_vmctx, values_vec)
}
}
fn make_trampoline(
isa: &dyn TargetIsa,
code_memory: &mut CodeMemory,
fn_builder_ctx: &mut FunctionBuilderContext,
signature: &ir::Signature,
) -> *mut [VMFunctionBody] {
let pointer_type = isa.pointer_type();
let mut stub_sig = ir::Signature::new(isa.frontend_config().default_call_conv);
stub_sig.params.push(ir::AbiParam::special(
pointer_type,
ir::ArgumentPurpose::VMContext,
));
stub_sig.params.push(ir::AbiParam::new(pointer_type));
stub_sig.params.push(ir::AbiParam::new(pointer_type));
let value_size = mem::size_of::<u128>();
let values_vec_len = ((value_size as usize)
* cmp::max(signature.params.len() - 2, signature.returns.len()))
as u32;
let mut context = Context::new();
context.func = Function::with_name_signature(ExternalName::user(0, 0), signature.clone());
let ss = context.func.create_stack_slot(StackSlotData::new(
StackSlotKind::ExplicitSlot,
values_vec_len,
));
{
let mut builder = FunctionBuilder::new(&mut context.func, fn_builder_ctx);
let block0 = builder.create_block();
builder.append_block_params_for_function_params(block0);
builder.switch_to_block(block0);
builder.seal_block(block0);
let values_vec_ptr_val = builder.ins().stack_addr(pointer_type, ss, 0);
let mflags = MemFlags::trusted();
for i in 2..signature.params.len() {
let val = builder.func.dfg.block_params(block0)[i];
builder.ins().store(
mflags,
val,
values_vec_ptr_val,
((i - 2) * value_size) as i32,
);
}
let block_params = builder.func.dfg.block_params(block0);
let vmctx_ptr_val = block_params[0];
let caller_vmctx_ptr_val = block_params[1];
let callee_args = vec![vmctx_ptr_val, caller_vmctx_ptr_val, values_vec_ptr_val];
let new_sig = builder.import_signature(stub_sig);
let callee_value = builder
.ins()
.iconst(pointer_type, stub_fn as *const VMFunctionBody as i64);
builder
.ins()
.call_indirect(new_sig, callee_value, &callee_args);
let mflags = MemFlags::trusted();
let mut results = Vec::new();
for (i, r) in signature.returns.iter().enumerate() {
let load = builder.ins().load(
r.value_type,
mflags,
values_vec_ptr_val,
(i * value_size) as i32,
);
results.push(load);
}
builder.ins().return_(&results);
builder.finalize()
}
let mut code_buf: Vec<u8> = Vec::new();
let mut reloc_sink = trampoline::TrampolineRelocSink::default();
let mut trap_sink = binemit::NullTrapSink {};
let mut stack_map_sink = binemit::NullStackMapSink {};
context
.compile_and_emit(
isa,
&mut code_buf,
&mut reloc_sink,
&mut trap_sink,
&mut stack_map_sink,
)
.map_err(|error| pretty_error(&context.func, Some(isa), error))
.expect("compile_and_emit");
let unwind_info = context
.create_unwind_info(isa)
.map_err(|error| pretty_error(&context.func, Some(isa), error))
.expect("create unwind information");
assert!(reloc_sink.relocs().is_empty());
code_memory
.allocate_for_function(&CompiledFunction {
body: code_buf,
jt_offsets: context.func.jt_offsets,
unwind_info,
relocations: Default::default(),
address_map: Default::default(),
stack_maps: Default::default(),
stack_slots: Default::default(),
traps: Default::default(),
value_labels_ranges: Default::default(),
})
.expect("allocate_for_function")
}
pub fn create_handle_with_function(
ft: &FuncType,
func: Box<dyn Fn(*mut VMContext, *mut u128) -> Result<(), Trap>>,
store: &Store,
) -> Result<(StoreInstanceHandle, VMTrampoline)> {
let isa = store.engine().config().target_isa_with_reference_types();
let pointer_type = isa.pointer_type();
let sig = ft.get_wasmtime_signature(pointer_type);
let wft = ft.as_wasm_func_type();
let mut fn_builder_ctx = FunctionBuilderContext::new();
let mut module = Module::new();
let mut finished_functions = PrimaryMap::new();
let mut code_memory = CodeMemory::new();
let sig_id = SignatureIndex::from_u32(u32::max_value() - 1);
module.types.push(ModuleType::Function(sig_id));
let func_id = module.functions.push(sig_id);
module
.exports
.insert(String::new(), wasm::EntityIndex::Function(func_id));
let trampoline = make_trampoline(isa.as_ref(), &mut code_memory, &mut fn_builder_ctx, &sig);
finished_functions.push(trampoline);
let trampoline = trampoline::make_trampoline(
&*isa,
&mut code_memory,
&mut fn_builder_ctx,
&sig,
mem::size_of::<u128>(),
)?;
let shared_signature_id = store.signatures().borrow_mut().register(wft, trampoline);
code_memory.publish(isa.as_ref());
let trampoline_state = TrampolineState { func, code_memory };
create_handle(
module,
store,
finished_functions,
Box::new(trampoline_state),
&[],
Some(shared_signature_id),
)
.map(|instance| (instance, trampoline))
}
pub unsafe fn create_handle_with_raw_function(
ft: &FuncType,
func: *mut [VMFunctionBody],
trampoline: VMTrampoline,
store: &Store,
state: Box<dyn Any>,
) -> Result<StoreInstanceHandle> {
let wft = ft.as_wasm_func_type();
let mut module = Module::new();
let mut finished_functions = PrimaryMap::new();
let sig_id = SignatureIndex::from_u32(u32::max_value() - 1);
module.types.push(ModuleType::Function(sig_id));
let func_id = module.functions.push(sig_id);
module
.exports
.insert(String::new(), wasm::EntityIndex::Function(func_id));
finished_functions.push(func);
let shared_signature_id = store.signatures().borrow_mut().register(wft, trampoline);
create_handle(
module,
store,
finished_functions,
state,
&[],
Some(shared_signature_id),
)
}