src/librustc_trans/cabi_x86.rs

   1 // Copyright 2013 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use llvm::*;
  12 use abi::{ArgAttribute, FnType};
  13 use type_::Type;
  14 use super::common::*;
  15 use super::machine::*;
  16
  17 pub fn compute_abi_info(ccx: &CrateContext, fty: &mut FnType) {
  18     if !fty.ret.is_ignore() {
  19         if fty.ret.ty.kind() == Struct {
  20             // Returning a structure. Most often, this will use
  21             // a hidden first argument. On some platforms, though,
  22             // small structs are returned as integers.
  23             //
  24             // Some links:
  25             // http://www.angelcode.com/dev/callconv/callconv.html
  26             // Clang's ABI handling is in lib/CodeGen/TargetInfo.cpp
  27             let t = &ccx.sess().target.target;
  28             if t.options.is_like_osx || t.options.is_like_windows
  29                 || t.options.is_like_openbsd {
  30                 match llsize_of_alloc(ccx, fty.ret.ty) {
  31                     1 => fty.ret.cast = Some(Type::i8(ccx)),
  32                     2 => fty.ret.cast = Some(Type::i16(ccx)),
  33                     4 => fty.ret.cast = Some(Type::i32(ccx)),
  34                     8 => fty.ret.cast = Some(Type::i64(ccx)),
  35                     _ => fty.ret.make_indirect(ccx)
  36                 }
  37             } else {
  38                 fty.ret.make_indirect(ccx);
  39             }
  40         } else {
  41             fty.ret.extend_integer_width_to(32);
  42         }
  43     }
  44
  45     for arg in &mut fty.args {
  46         if arg.is_ignore() { continue; }
  47         if arg.ty.kind() == Struct {
  48             arg.make_indirect(ccx);
  49             arg.attrs.set(ArgAttribute::ByVal);
  50         } else {
  51             arg.extend_integer_width_to(32);
  52         }
  53     }
  54 }