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expose values to the host in a new way

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Folkert 2020-10-31 22:44:35 +01:00
parent 95a69f5a9b
commit 27598f6e78
1 changed files with 73 additions and 7 deletions
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80
compiler/gen/src/llvm/build.rs
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@ -1842,6 +1842,76 @@ pub fn create_entry_block_alloca<'a, 'ctx>(
builder.build_alloca(basic_type, name)
}
fn expose_function_to_host<'a, 'ctx, 'env>(
env: &Env<'a, 'ctx, 'env>,
roc_function: &FunctionValue<'ctx>,
) {
use inkwell::types::BasicType;
let roc_function_type = roc_function.get_type();
// STEP 1: turn `f : a,b,c -> d` into `f : a,b,c, &d -> {}`
let mut argument_types = roc_function_type.get_param_types();
let return_type = roc_function_type.get_return_type().unwrap();
let output_type = return_type.ptr_type(AddressSpace::Generic);
argument_types.push(output_type.into());
let c_function_type = env.context.void_type().fn_type(&argument_types, false);
let c_function_name: String = format!("{}_exposed", roc_function.get_name().to_str().unwrap());
let c_function = env.module.add_function(
c_function_name.as_str(),
c_function_type,
Some(Linkage::External),
);
// STEP 2: build the exposed function's body
let builder = env.builder;
let context = env.context;
let entry = context.append_basic_block(c_function, "entry");
builder.position_at_end(entry);
// drop the final argument, which is the pointer we write the result into
let args = c_function.get_params();
let output_arg_index = args.len() - 1;
let args = &args[..args.len() - 1];
debug_assert_eq!(args.len(), roc_function.get_params().len());
let call_wrapped = builder.build_call(roc_function.clone(), args, "call_wrapped_function");
call_wrapped.set_call_convention(FAST_CALL_CONV);
let call_result = call_wrapped.try_as_basic_value().left().unwrap();
let output_arg = c_function
.get_nth_param(output_arg_index as u32)
.unwrap()
.into_pointer_value();
builder.build_store(output_arg, call_result);
builder.build_return(None);
// STEP 3: build a {} -> u64 function that gives the size of the return type
let size_function_type = env.context.i64_type().fn_type(&[], false);
let size_function_name: String = format!("{}_size", roc_function.get_name().to_str().unwrap());
let size_function = env.module.add_function(
size_function_name.as_str(),
size_function_type,
Some(Linkage::External),
);
let entry = context.append_basic_block(size_function, "entry");
builder.position_at_end(entry);
let size: BasicValueEnum = return_type.size_of().unwrap().into();
builder.build_return(Some(&size));
}
pub fn build_proc_header<'a, 'ctx, 'env>(
env: &Env<'a, 'ctx, 'env>,
layout_ids: &mut LayoutIds<'a>,
@ -1871,14 +1941,10 @@ pub fn build_proc_header<'a, 'ctx, 'env>(
.module
.add_function(fn_name.as_str(), fn_type, Some(Linkage::Private));
fn_val.set_call_conventions(FAST_CALL_CONV);
if env.exposed_to_host.contains(&symbol) {
// If this is an external-facing function, it'll use the C calling convention
// and external linkage.
fn_val.set_linkage(Linkage::External);
fn_val.set_call_conventions(C_CALL_CONV);
} else {
// If it's an internal-only function, it should use the fast calling conention.
fn_val.set_call_conventions(FAST_CALL_CONV);
expose_function_to_host(env, &fn_val);
}
fn_val