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108 lines
4.0 KiB
Rust
108 lines
4.0 KiB
Rust
// rsbegin.o and rsend.o are the so called "compiler runtime startup objects".
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// They contain code needed to correctly initialize the compiler runtime.
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//
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// When an executable or dylib image is linked, all user code and libraries are
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// "sandwiched" between these two object files, so code or data from rsbegin.o
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// become first in the respective sections of the image, whereas code and data
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// from rsend.o become the last ones. This effect can be used to place symbols
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// at the beginning or at the end of a section, as well as to insert any required
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// headers or footers.
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//
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// Note that the actual module entry point is located in the C runtime startup
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// object (usually called `crtX.o`), which then invokes initialization callbacks
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// of other runtime components (registered via yet another special image section).
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#![feature(no_core)]
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#![feature(lang_items)]
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#![feature(auto_traits)]
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#![crate_type = "rlib"]
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#![no_core]
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#![allow(non_camel_case_types)]
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#![allow(internal_features)]
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#[lang = "sized"]
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trait Sized {}
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#[lang = "sync"]
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auto trait Sync {}
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#[lang = "copy"]
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trait Copy {}
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#[lang = "freeze"]
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auto trait Freeze {}
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#[lang = "drop_in_place"]
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#[inline]
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#[allow(unconditional_recursion)]
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pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
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drop_in_place(to_drop);
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}
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// Frame unwind info registration
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//
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// Each module's image contains a frame unwind info section (usually
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// ".eh_frame"). When a module is loaded/unloaded into the process, the
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// unwinder must be informed about the location of this section in memory. The
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// methods of achieving that vary by the platform. On some (e.g., Linux), the
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// unwinder can discover unwind info sections on its own (by dynamically
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// enumerating currently loaded modules via the dl_iterate_phdr() API and
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// finding their ".eh_frame" sections); Others, like Windows, require modules
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// to actively register their unwind info sections via unwinder API.
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#[cfg(all(target_os = "windows", target_arch = "x86", target_env = "gnu"))]
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pub mod eh_frames {
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#[no_mangle]
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#[link_section = ".eh_frame"]
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// Marks beginning of the stack frame unwind info section
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pub static __EH_FRAME_BEGIN__: [u8; 0] = [];
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// Scratch space for unwinder's internal book-keeping.
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// This is defined as `struct object` in $GCC/libgcc/unwind-dw2-fde.h.
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static mut OBJ: [isize; 6] = [0; 6];
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macro_rules! impl_copy {
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($($t:ty)*) => {
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$(
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impl ::Copy for $t {}
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)*
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}
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}
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impl_copy! {
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usize u8 u16 u32 u64 u128
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isize i8 i16 i32 i64 i128
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f32 f64
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bool char
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}
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// Unwind info registration/deregistration routines.
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extern "C" {
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fn __register_frame_info(eh_frame_begin: *const u8, object: *mut u8);
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fn __deregister_frame_info(eh_frame_begin: *const u8, object: *mut u8);
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}
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unsafe extern "C" fn init() {
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// register unwind info on module startup
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__register_frame_info(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8);
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}
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unsafe extern "C" fn uninit() {
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// unregister on shutdown
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__deregister_frame_info(&__EH_FRAME_BEGIN__ as *const u8, &mut OBJ as *mut _ as *mut u8);
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}
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// MinGW-specific init/uninit routine registration
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pub mod mingw_init {
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// MinGW's startup objects (crt0.o / dllcrt0.o) will invoke global constructors in the
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// .ctors and .dtors sections on startup and exit. In the case of DLLs, this is done when
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// the DLL is loaded and unloaded.
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//
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// The linker will sort the sections, which ensures that our callbacks are located at the
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// end of the list. Since constructors are run in reverse order, this ensures that our
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// callbacks are the first and last ones executed.
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#[link_section = ".ctors.65535"] // .ctors.* : C initialization callbacks
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pub static P_INIT: unsafe extern "C" fn() = super::init;
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#[link_section = ".dtors.65535"] // .dtors.* : C termination callbacks
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pub static P_UNINIT: unsafe extern "C" fn() = super::uninit;
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}
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}
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