M-Labs/nac3
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core: Fix passing structure arguments to extern functions

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All parameters with a structure type in extern functions are marked as
`byref` instead of `byval`, as most ABIs require the first several
arguments to be passed in registers before spilling into the stack.

`byval` breaks this contract by explicitly requiring all arguments to be
 passed in the stack, breaking interop with libraries written in other
 languages.
This commit is contained in:
David Mak 2023-09-21 15:25:24 +08:00
parent 176f250bdb
commit cb39f61e79
1 changed files with 18 additions and 6 deletions
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24
nac3core/src/codegen/expr.rs
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@ -365,6 +365,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
let mut return_slot = None;
if fun.count_params() > 0 {
let sret_id = Attribute::get_named_enum_kind_id("sret");
let byref_id = Attribute::get_named_enum_kind_id("byref");
let byval_id = Attribute::get_named_enum_kind_id("byval");
let offset = if fun.get_enum_attribute(AttributeLoc::Param(0), sret_id).is_some() {
@ -376,7 +377,8 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
0
};
for (i, param) in params.iter().enumerate() {
if fun.get_enum_attribute(AttributeLoc::Param((i + offset) as u32), byval_id).is_some() {
let loc = AttributeLoc::Param((i + offset) as u32);
if fun.get_enum_attribute(loc, byref_id).is_some() || fun.get_enum_attribute(loc, byval_id).is_some() {
// lazy update
if loc_params.is_empty() {
loc_params.extend(params[0..i+offset].iter().copied());
@ -745,11 +747,11 @@ pub fn gen_call<'ctx, 'a, G: CodeGenerator>(
Some(ctx.get_llvm_abi_type(generator, fun.0.ret))
};
let has_sret = ret_type.map_or(false, |ret_type| need_sret(ctx.ctx, ret_type));
let mut byvals = Vec::new();
let mut byrefs = Vec::new();
let mut params = args.iter().enumerate()
.map(|(i, arg)| match ctx.get_llvm_abi_type(generator, arg.ty) {
BasicTypeEnum::StructType(ty) if is_extern => {
byvals.push((i, ty));
byrefs.push((i, ty));
ty.ptr_type(AddressSpace::default()).into()
},
x => x
@ -770,9 +772,19 @@ pub fn gen_call<'ctx, 'a, G: CodeGenerator>(
} else {
0
};
for (i, ty) in byvals {
fun_val.add_attribute(AttributeLoc::Param((i as u32) + offset),
ctx.ctx.create_type_attribute(Attribute::get_named_enum_kind_id("byval"), ty.as_any_type_enum()));
// The attribute ID used to mark arguments of a structure type.
// Structure-Typed parameters of extern functions must **not** be marked as `byval`, as
// `byval` explicitly specifies that the argument is to be passed on the stack, which breaks
// on most ABIs where the first several arguments are expected to be passed in registers.
let passing_attr_id = Attribute::get_named_enum_kind_id(
if is_extern { "byref" } else { "byval" }
);
for (i, ty) in byrefs {
fun_val.add_attribute(
AttributeLoc::Param((i as u32) + offset),
ctx.ctx.create_type_attribute(passing_attr_id, ty.as_any_type_enum())
);
}
fun_val
});