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use crate::abi::call::{ArgAbi, FnAbi, Reg, RegKind, Uniform};
use crate::abi::{HasDataLayout, TyAbiInterface};
/// Indicates the variant of the AArch64 ABI we are compiling for.
/// Used to accommodate Apple and Microsoft's deviations from the usual AAPCS ABI.
///
/// Corresponds to Clang's `AArch64ABIInfo::ABIKind`.
#[derive(Copy, Clone, PartialEq)]
pub enum AbiKind {
AAPCS,
DarwinPCS,
Win64,
}
fn is_homogeneous_aggregate<'a, Ty, C>(cx: &C, arg: &mut ArgAbi<'a, Ty>) -> Option<Uniform>
where
Ty: TyAbiInterface<'a, C> + Copy,
C: HasDataLayout,
{
arg.layout.homogeneous_aggregate(cx).ok().and_then(|ha| ha.unit()).and_then(|unit| {
let size = arg.layout.size;
// Ensure we have at most four uniquely addressable members.
if size > unit.size.checked_mul(4, cx).unwrap() {
return None;
}
let valid_unit = match unit.kind {
RegKind::Integer => false,
RegKind::Float => true,
RegKind::Vector => size.bits() == 64 || size.bits() == 128,
};
valid_unit.then_some(Uniform { unit, total: size })
})
}
fn classify_ret<'a, Ty, C>(cx: &C, ret: &mut ArgAbi<'a, Ty>, kind: AbiKind)
where
Ty: TyAbiInterface<'a, C> + Copy,
C: HasDataLayout,
{
if !ret.layout.is_sized() {
// Not touching this...
return;
}
if !ret.layout.is_aggregate() {
if kind == AbiKind::DarwinPCS {
// On Darwin, when returning an i8/i16, it must be sign-extended to 32 bits,
// and likewise a u8/u16 must be zero-extended to 32-bits.
// See also: <https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms#Pass-Arguments-to-Functions-Correctly>
ret.extend_integer_width_to(32)
}
return;
}
if let Some(uniform) = is_homogeneous_aggregate(cx, ret) {
ret.cast_to(uniform);
return;
}
let size = ret.layout.size;
let bits = size.bits();
if bits <= 128 {
ret.cast_to(Uniform { unit: Reg::i64(), total: size });
return;
}
ret.make_indirect();
}
fn classify_arg<'a, Ty, C>(cx: &C, arg: &mut ArgAbi<'a, Ty>, kind: AbiKind)
where
Ty: TyAbiInterface<'a, C> + Copy,
C: HasDataLayout,
{
if !arg.layout.is_sized() {
// Not touching this...
return;
}
if !arg.layout.is_aggregate() {
if kind == AbiKind::DarwinPCS {
// On Darwin, when passing an i8/i16, it must be sign-extended to 32 bits,
// and likewise a u8/u16 must be zero-extended to 32-bits.
// See also: <https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms#Pass-Arguments-to-Functions-Correctly>
arg.extend_integer_width_to(32);
}
return;
}
if let Some(uniform) = is_homogeneous_aggregate(cx, arg) {
arg.cast_to(uniform);
return;
}
let size = arg.layout.size;
let align = if kind == AbiKind::AAPCS {
// When passing small aggregates by value, the AAPCS ABI mandates using the unadjusted
// alignment of the type (not including `repr(align)`).
// This matches behavior of `AArch64ABIInfo::classifyArgumentType` in Clang.
// See: <https://github.com/llvm/llvm-project/blob/5e691a1c9b0ad22689d4a434ddf4fed940e58dec/clang/lib/CodeGen/TargetInfo.cpp#L5816-L5823>
arg.layout.unadjusted_abi_align
} else {
arg.layout.align.abi
};
if size.bits() <= 128 {
if align.bits() == 128 {
arg.cast_to(Uniform { unit: Reg::i128(), total: size });
} else {
arg.cast_to(Uniform { unit: Reg::i64(), total: size });
}
return;
}
arg.make_indirect();
}
pub fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>, kind: AbiKind)
where
Ty: TyAbiInterface<'a, C> + Copy,
C: HasDataLayout,
{
if !fn_abi.ret.is_ignore() {
classify_ret(cx, &mut fn_abi.ret, kind);
}
for arg in fn_abi.args.iter_mut() {
if arg.is_ignore() {
continue;
}
classify_arg(cx, arg, kind);
}
}
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