rust/src/rtstartup/rsbegin.rs
2017-09-28 01:30:25 -07:00

96 lines
3.8 KiB
Rust

// Copyright 2015 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.
// rsbegin.o and rsend.o are the so called "compiler runtime startup objects".
// They contain code needed to correctly initialize the compiler runtime.
//
// When an executable or dylib image is linked, all user code and libraries are
// "sandwiched" between these two object files, so code or data from rsbegin.o
// become first in the respective sections of the image, whereas code and data
// from rsend.o become the last ones. This effect can be used to place symbols
// at the beginning or at the end of a section, as well as to insert any required
// headers or footers.
//
// Note that the actual module entry point is located in the C runtime startup
// object (usually called `crtX.o), which then invokes initialization callbacks
// of other runtime components (registered via yet another special image section).
#![feature(no_core, lang_items, optin_builtin_traits)]
#![crate_type="rlib"]
#![no_core]
#![allow(non_camel_case_types)]
#[lang = "sized"]
trait Sized {}
#[lang = "sync"]
trait Sync {}
impl Sync for .. {}
#[lang = "copy"]
trait Copy {}
#[lang = "freeze"]
trait Freeze {}
impl Freeze for .. {}
#[lang = "drop_in_place"]
#[inline]
#[allow(unconditional_recursion)]
pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
drop_in_place(to_drop);
}
#[cfg(all(target_os="windows", target_arch = "x86", target_env="gnu"))]
pub mod eh_frames {
#[no_mangle]
#[link_section = ".eh_frame"]
// Marks beginning of the stack frame unwind info section
pub static __EH_FRAME_BEGIN__: [u8; 0] = [];
// Scratch space for unwinder's internal book-keeping.
// This is defined as `struct object` in $GCC/libgcc/unwind-dw2-fde.h.
static mut OBJ: [isize; 6] = [0; 6];
// Unwind info registration/deregistration routines.
// See the docs of `unwind` module in libstd.
extern "C" {
fn rust_eh_register_frames(eh_frame_begin: *const u8, object: *mut u8);
fn rust_eh_unregister_frames(eh_frame_begin: *const u8, object: *mut u8);
}
unsafe fn init() {
// register unwind info on module startup
rust_eh_register_frames(&__EH_FRAME_BEGIN__ as *const u8,
&mut OBJ as *mut _ as *mut u8);
}
unsafe fn uninit() {
// unregister on shutdown
rust_eh_unregister_frames(&__EH_FRAME_BEGIN__ as *const u8,
&mut OBJ as *mut _ as *mut u8);
}
// MSVC-specific init/uninit routine registration
pub mod ms_init {
// .CRT$X?? sections are roughly analogous to ELF's .init_array and .fini_array,
// except that they exploit the fact that linker will sort them alphabitically,
// so e.g. sections with names between .CRT$XIA and .CRT$XIZ are guaranteed to be
// placed between those two, without requiring any ordering of objects on the linker
// command line.
// Note that ordering of same-named sections from different objects is not guaranteed.
// Since .CRT$XIA contains init array's header symbol, which must always come first,
// we place our initialization callback into .CRT$XIB.
#[link_section = ".CRT$XIB"] // .CRT$XI? : C initialization callbacks
pub static P_INIT: unsafe fn() = super::init;
#[link_section = ".CRT$XTY"] // .CRT$XT? : C termination callbacks
pub static P_UNINIT: unsafe fn() = super::uninit;
}
}