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jit-minimal.rs
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92 lines (76 loc) · 3.03 KB
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use codegen::ir::UserFuncName;
use cranelift::prelude::*;
use cranelift_jit::{JITBuilder, JITModule};
use cranelift_module::{Linkage, Module, default_libcall_names};
use std::mem;
fn main() {
let mut flag_builder = settings::builder();
flag_builder.set("use_colocated_libcalls", "false").unwrap();
// FIXME set back to true once the x64 backend supports it.
flag_builder.set("is_pic", "false").unwrap();
let isa_builder = cranelift_native::builder().unwrap_or_else(|msg| {
panic!("host machine is not supported: {msg}");
});
let isa = isa_builder
.finish(settings::Flags::new(flag_builder))
.unwrap();
let mut module = JITModule::new(JITBuilder::with_isa(isa, default_libcall_names()));
let mut ctx = module.make_context();
let mut func_ctx = FunctionBuilderContext::new();
let mut sig_a = module.make_signature();
sig_a.params.push(AbiParam::new(types::I32));
sig_a.returns.push(AbiParam::new(types::I32));
let mut sig_b = module.make_signature();
sig_b.returns.push(AbiParam::new(types::I32));
let func_a = module
.declare_function("a", Linkage::Local, &sig_a)
.unwrap();
let func_b = module
.declare_function("b", Linkage::Local, &sig_b)
.unwrap();
ctx.func.signature = sig_a;
ctx.func.name = UserFuncName::user(0, func_a.as_u32());
{
let mut bcx: FunctionBuilder = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
let block = bcx.create_block();
bcx.switch_to_block(block);
bcx.append_block_params_for_function_params(block);
let param = bcx.block_params(block)[0];
let cst = bcx.ins().iconst(types::I32, 37);
let add = bcx.ins().iadd(cst, param);
bcx.ins().return_(&[add]);
bcx.seal_all_blocks();
bcx.finalize();
}
module.define_function(func_a, &mut ctx).unwrap();
module.clear_context(&mut ctx);
ctx.func.signature = sig_b;
ctx.func.name = UserFuncName::user(0, func_b.as_u32());
{
let mut bcx: FunctionBuilder = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
let block = bcx.create_block();
bcx.switch_to_block(block);
let local_func = module.declare_func_in_func(func_a, &mut bcx.func);
let arg = bcx.ins().iconst(types::I32, 5);
let call = bcx.ins().call(local_func, &[arg]);
let value = {
let results = bcx.inst_results(call);
assert_eq!(results.len(), 1);
results[0]
};
bcx.ins().return_(&[value]);
bcx.seal_all_blocks();
bcx.finalize();
}
module.define_function(func_b, &mut ctx).unwrap();
module.clear_context(&mut ctx);
// Perform linking.
module.finalize_definitions().unwrap();
// Get a raw pointer to the generated code.
let code_b = module.get_finalized_function(func_b);
// Cast it to a rust function pointer type.
let ptr_b = unsafe { mem::transmute::<_, extern "C" fn() -> u32>(code_b) };
// Call it!
let res = ptr_b();
assert_eq!(res, 42);
}