wasmer-compiler-cranelift 7.4.2

// This file contains code from external sources.
// Attributions: https://github.com/wasmerio/wasmer/blob/main/docs/ATTRIBUTIONS.md

//! A trampoline generator for calling Wasm functions easily.
//!
//! That way, you can start calling Wasm functions doing things like:
//! ```ignore
//! let my_func = instance.exports.get("func");
//! my_func.call([1, 2])
//! ```
use crate::{
    CraneliftCallbacks, abi,
    translator::{compiled_function_unwind_info, signature_to_cranelift_ir},
};
use cranelift_codegen::{
    Context,
    ir::{self, InstBuilder},
    isa::TargetIsa,
};
use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext};
use std::mem;
use target_lexicon::Architecture;
use wasmer_compiler::{misc::CompiledKind, types::function::FunctionBody};
use wasmer_types::{CompileError, FunctionType};

/// Create a trampoline for invoking a WebAssembly function.
pub fn make_trampoline_function_call(
    callbacks: &Option<CraneliftCallbacks>,
    isa: &dyn TargetIsa,
    arch: Architecture,
    fn_builder_ctx: &mut FunctionBuilderContext,
    kind: &CompiledKind,
    func_type: &FunctionType,
    module_hash: &Option<String>,
) -> Result<FunctionBody, CompileError> {
    let pointer_type = isa.pointer_type();
    let frontend_config = isa.frontend_config();
    let signature = signature_to_cranelift_ir(func_type, frontend_config, arch);
    let mut wrapper_sig = ir::Signature::new(frontend_config.default_call_conv);

    // Add the callee `vmctx` parameter.
    wrapper_sig.params.push(ir::AbiParam::special(
        pointer_type,
        ir::ArgumentPurpose::VMContext,
    ));

    // Add the `callee_address` parameter.
    wrapper_sig.params.push(ir::AbiParam::new(pointer_type));

    // Add the `values_vec` parameter.
    wrapper_sig.params.push(ir::AbiParam::new(pointer_type));

    let mut context = Context::new();
    context.func = ir::Function::with_name_signature(ir::UserFuncName::user(0, 0), wrapper_sig);

    let value_size = mem::size_of::<u128>();
    {
        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 (vmctx_ptr_val, callee_value, values_vec_ptr_val) = {
            let params = builder.func.dfg.block_params(block0);
            (params[0], params[1], params[2])
        };

        // Load the argument values out of `values_vec` and add special ABI arguments.
        let return_abi = abi::classify_returns(arch, func_type.results());
        let sret = match &return_abi {
            wasmer_compiler::abi::ReturnAbi::Sret(types) => Some(abi::allocate_return_area(
                &mut builder,
                types,
                frontend_config,
            )),
            _ => None,
        };
        let mflags = ir::MemFlagsData::trusted();
        let mut wasm_param = 0usize;
        let callee_args = signature
            .params
            .iter()
            .map(|r| match r.purpose {
                ir::ArgumentPurpose::StructReturn => sret.as_ref().unwrap().0,
                ir::ArgumentPurpose::VMContext => vmctx_ptr_val,
                ir::ArgumentPurpose::Normal => {
                    let value = builder.ins().load(
                        r.value_type,
                        mflags,
                        values_vec_ptr_val,
                        (wasm_param * value_size) as i32,
                    );
                    wasm_param += 1;
                    value
                }
                _ => unreachable!("unexpected WebAssembly ABI parameter"),
            })
            .collect::<Vec<_>>();

        let new_sig = builder.import_signature(signature);

        let call = builder
            .ins()
            .call_indirect(new_sig, callee_value, &callee_args);

        let carriers = builder.func.dfg.inst_results(call).to_vec();
        let results = match (&return_abi, sret) {
            (wasmer_compiler::abi::ReturnAbi::Sret(types), Some((ptr, layout))) => {
                abi::load_sret(&mut builder, ptr, &layout, types, frontend_config)
            }
            _ => {
                abi::unpack_register_returns(&mut builder, &return_abi, &carriers, frontend_config)
            }
        };

        // Store the return values into `values_vec`.
        let mflags = ir::MemFlagsData::trusted();
        for (i, r) in results.iter().enumerate() {
            builder
                .ins()
                .store(mflags, *r, values_vec_ptr_val, (i * value_size) as i32);
        }

        builder.ins().return_(&[]);
        builder.finalize(frontend_config)
    }

    if let Some(callbacks) = callbacks.as_ref() {
        callbacks.preopt_ir(
            kind,
            module_hash,
            context.func.display().to_string().as_bytes(),
        );
    }

    let mut code_buf = Vec::new();
    let mut ctrl_plane = Default::default();
    let compiled = context
        .compile(isa, &mut ctrl_plane)
        .map_err(|error| CompileError::Codegen(error.inner.to_string()))?;
    code_buf.extend_from_slice(compiled.code_buffer());

    if let Some(callbacks) = callbacks.as_ref() {
        callbacks.obj_memory_buffer(kind, module_hash, &code_buf);
        callbacks.asm_memory_buffer(kind, module_hash, arch, &code_buf)?;
    }

    let unwind_info = compiled_function_unwind_info(isa, &context)?.maybe_into_to_windows_unwind();

    Ok(FunctionBody {
        body: code_buf,
        unwind_info,
    })
}