| // 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::{ArgAttribute, FnType, LayoutExt, PassMode, Reg, RegKind}; |
| use common::CrateContext; |
| |
| use rustc::ty::layout::{self, TyLayout}; |
| |
| #[derive(PartialEq)] |
| pub enum Flavor { |
| General, |
| Fastcall |
| } |
| |
| fn is_single_fp_element<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, |
| layout: TyLayout<'tcx>) -> bool { |
| match layout.abi { |
| layout::Abi::Scalar(ref scalar) => { |
| match scalar.value { |
| layout::F32 | layout::F64 => true, |
| _ => false |
| } |
| } |
| layout::Abi::Aggregate { .. } => { |
| if layout.fields.count() == 1 && layout.fields.offset(0).bytes() == 0 { |
| is_single_fp_element(ccx, layout.field(ccx, 0)) |
| } else { |
| false |
| } |
| } |
| _ => false |
| } |
| } |
| |
| pub fn compute_abi_info<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, |
| fty: &mut FnType<'tcx>, |
| flavor: Flavor) { |
| if !fty.ret.is_ignore() { |
| if fty.ret.layout.is_aggregate() { |
| // Returning a structure. Most often, this will use |
| // a hidden first argument. On some platforms, though, |
| // small structs are returned as integers. |
| // |
| // Some links: |
| // http://www.angelcode.com/dev/callconv/callconv.html |
| // Clang's ABI handling is in lib/CodeGen/TargetInfo.cpp |
| let t = &ccx.sess().target.target; |
| if t.options.is_like_osx || t.options.is_like_windows |
| || t.options.is_like_openbsd { |
| // According to Clang, everyone but MSVC returns single-element |
| // float aggregates directly in a floating-point register. |
| if !t.options.is_like_msvc && is_single_fp_element(ccx, fty.ret.layout) { |
| match fty.ret.layout.size.bytes() { |
| 4 => fty.ret.cast_to(Reg::f32()), |
| 8 => fty.ret.cast_to(Reg::f64()), |
| _ => fty.ret.make_indirect() |
| } |
| } else { |
| match fty.ret.layout.size.bytes() { |
| 1 => fty.ret.cast_to(Reg::i8()), |
| 2 => fty.ret.cast_to(Reg::i16()), |
| 4 => fty.ret.cast_to(Reg::i32()), |
| 8 => fty.ret.cast_to(Reg::i64()), |
| _ => fty.ret.make_indirect() |
| } |
| } |
| } else { |
| fty.ret.make_indirect(); |
| } |
| } else { |
| fty.ret.extend_integer_width_to(32); |
| } |
| } |
| |
| for arg in &mut fty.args { |
| if arg.is_ignore() { continue; } |
| if arg.layout.is_aggregate() { |
| arg.make_indirect_byval(); |
| } else { |
| arg.extend_integer_width_to(32); |
| } |
| } |
| |
| if flavor == Flavor::Fastcall { |
| // Mark arguments as InReg like clang does it, |
| // so our fastcall is compatible with C/C++ fastcall. |
| |
| // Clang reference: lib/CodeGen/TargetInfo.cpp |
| // See X86_32ABIInfo::shouldPrimitiveUseInReg(), X86_32ABIInfo::updateFreeRegs() |
| |
| // IsSoftFloatABI is only set to true on ARM platforms, |
| // which in turn can't be x86? |
| |
| let mut free_regs = 2; |
| |
| for arg in &mut fty.args { |
| let attrs = match arg.mode { |
| PassMode::Ignore | |
| PassMode::Indirect(_) => continue, |
| PassMode::Direct(ref mut attrs) => attrs, |
| PassMode::Pair(..) | |
| PassMode::Cast(_) => { |
| bug!("x86 shouldn't be passing arguments by {:?}", arg.mode) |
| } |
| }; |
| |
| // At this point we know this must be a primitive of sorts. |
| let unit = arg.layout.homogeneous_aggregate(ccx).unwrap(); |
| assert_eq!(unit.size, arg.layout.size); |
| if unit.kind == RegKind::Float { |
| continue; |
| } |
| |
| let size_in_regs = (arg.layout.size.bits() + 31) / 32; |
| |
| if size_in_regs == 0 { |
| continue; |
| } |
| |
| if size_in_regs > free_regs { |
| break; |
| } |
| |
| free_regs -= size_in_regs; |
| |
| if arg.layout.size.bits() <= 32 && unit.kind == RegKind::Integer { |
| attrs.set(ArgAttribute::InReg); |
| } |
| |
| if free_regs == 0 { |
| break; |
| } |
| } |
| } |
| } |