src/librustc_trans/cabi_x86_win64.rs

// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use abi::{ArgType, FnType, Reg};

use rustc::ty::layout;

// Win64 ABI: http://msdn.microsoft.com/en-us/library/zthk2dkh.aspx

pub fn compute_abi_info(fty: &mut FnType) {
    let fixup = |a: &mut ArgType| {
        match a.layout.abi {
            layout::Abi::Uninhabited => {}
            layout::Abi::ScalarPair(..) |
            layout::Abi::Aggregate { .. } => {
                match a.layout.size.bits() {
                    8 => a.cast_to(Reg::i8()),
                    16 => a.cast_to(Reg::i16()),
                    32 => a.cast_to(Reg::i32()),
                    64 => a.cast_to(Reg::i64()),
                    _ => a.make_indirect()
                }
            }
            layout::Abi::Vector { .. } => {
                // FIXME(eddyb) there should be a size cap here
                // (probably what clang calls "illegal vectors").
            }
            layout::Abi::Scalar(_) => {
                if a.layout.size.bytes() > 8 {
                    a.make_indirect();
                } else {
                    a.extend_integer_width_to(32);
                }
            }
        }
    };

    if !fty.ret.is_ignore() {
        fixup(&mut fty.ret);
    }
    for arg in &mut fty.args {
        if arg.is_ignore() { continue; }
        fixup(arg);
    }
}