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gcc.rs
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gcc.rs
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// 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.
#![allow(private_no_mangle_fns)]
use prelude::v1::*;
use any::Any;
use rt::libunwind as uw;
struct Exception {
uwe: uw::_Unwind_Exception,
cause: Option<Box<Any + Send + 'static>>,
}
pub unsafe fn panic(data: Box<Any + Send + 'static>) -> ! {
let exception: Box<_> = box Exception {
uwe: uw::_Unwind_Exception {
exception_class: rust_exception_class(),
exception_cleanup: exception_cleanup,
private: [0; uw::unwinder_private_data_size],
},
cause: Some(data),
};
let exception_param = Box::into_raw(exception) as *mut uw::_Unwind_Exception;
let error = uw::_Unwind_RaiseException(exception_param);
rtabort!("Could not unwind stack, error = {}", error as isize);
extern fn exception_cleanup(_unwind_code: uw::_Unwind_Reason_Code,
exception: *mut uw::_Unwind_Exception) {
rtdebug!("exception_cleanup()");
unsafe {
let _: Box<Exception> = Box::from_raw(exception as *mut Exception);
}
}
}
pub unsafe fn cleanup(ptr: *mut u8) -> Box<Any + Send + 'static> {
let my_ep = ptr as *mut Exception;
rtdebug!("caught {}", (*my_ep).uwe.exception_class);
let cause = (*my_ep).cause.take();
uw::_Unwind_DeleteException(ptr as *mut _);
cause.unwrap()
}
// Rust's exception class identifier. This is used by personality routines to
// determine whether the exception was thrown by their own runtime.
fn rust_exception_class() -> uw::_Unwind_Exception_Class {
// M O Z \0 R U S T -- vendor, language
0x4d4f5a_00_52555354
}
// We could implement our personality routine in pure Rust, however exception
// info decoding is tedious. More importantly, personality routines have to
// handle various platform quirks, which are not fun to maintain. For this
// reason, we attempt to reuse personality routine of the C language:
// __gcc_personality_v0.
//
// Since C does not support exception catching, __gcc_personality_v0 simply
// always returns _URC_CONTINUE_UNWIND in search phase, and always returns
// _URC_INSTALL_CONTEXT (i.e. "invoke cleanup code") in cleanup phase.
//
// This is pretty close to Rust's exception handling approach, except that Rust
// does have a single "catch-all" handler at the bottom of each thread's stack.
// So we have two versions of the personality routine:
// - rust_eh_personality, used by all cleanup landing pads, which never catches,
// so the behavior of __gcc_personality_v0 is perfectly adequate there, and
// - rust_eh_personality_catch, used only by rust_try(), which always catches.
//
// Note, however, that for implementation simplicity, rust_eh_personality_catch
// lacks code to install a landing pad, so in order to obtain exception object
// pointer (which it needs to return upstream), rust_try() employs another trick:
// it calls into the nested rust_try_inner(), whose landing pad does not resume
// unwinds. Instead, it extracts the exception pointer and performs a "normal"
// return.
//
// See also: rt/rust_try.ll
#[cfg(all(not(target_arch = "arm"),
not(all(windows, target_arch = "x86_64")),
not(test)))]
pub mod eabi {
use rt::libunwind as uw;
use libc::c_int;
extern {
fn __gcc_personality_v0(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code;
}
#[lang = "eh_personality"]
#[no_mangle]
extern fn rust_eh_personality(
version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context
) -> uw::_Unwind_Reason_Code
{
unsafe {
__gcc_personality_v0(version, actions, exception_class, ue_header,
context)
}
}
#[lang = "eh_personality_catch"]
#[no_mangle]
pub extern fn rust_eh_personality_catch(
_version: c_int,
actions: uw::_Unwind_Action,
_exception_class: uw::_Unwind_Exception_Class,
_ue_header: *mut uw::_Unwind_Exception,
_context: *mut uw::_Unwind_Context
) -> uw::_Unwind_Reason_Code
{
if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase
uw::_URC_HANDLER_FOUND // catch!
}
else { // cleanup phase
uw::_URC_INSTALL_CONTEXT
}
}
}
// iOS on armv7 is using SjLj exceptions and therefore requires to use
// a specialized personality routine: __gcc_personality_sj0
#[cfg(all(target_os = "ios", target_arch = "arm", not(test)))]
pub mod eabi {
use rt::libunwind as uw;
use libc::c_int;
extern {
fn __gcc_personality_sj0(version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code;
}
#[lang = "eh_personality"]
#[no_mangle]
pub extern fn rust_eh_personality(
version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context
) -> uw::_Unwind_Reason_Code
{
unsafe {
__gcc_personality_sj0(version, actions, exception_class, ue_header,
context)
}
}
#[lang = "eh_personality_catch"]
#[no_mangle]
pub extern fn rust_eh_personality_catch(
_version: c_int,
actions: uw::_Unwind_Action,
_exception_class: uw::_Unwind_Exception_Class,
_ue_header: *mut uw::_Unwind_Exception,
_context: *mut uw::_Unwind_Context
) -> uw::_Unwind_Reason_Code
{
if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase
uw::_URC_HANDLER_FOUND // catch!
}
else { // cleanup phase
unsafe {
__gcc_personality_sj0(_version, actions, _exception_class, _ue_header,
_context)
}
}
}
}
// ARM EHABI uses a slightly different personality routine signature,
// but otherwise works the same.
#[cfg(all(target_arch = "arm", not(target_os = "ios"), not(test)))]
pub mod eabi {
use rt::libunwind as uw;
use libc::c_int;
extern {
fn __gcc_personality_v0(state: uw::_Unwind_State,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context)
-> uw::_Unwind_Reason_Code;
}
#[lang = "eh_personality"]
#[no_mangle]
extern fn rust_eh_personality(
state: uw::_Unwind_State,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context
) -> uw::_Unwind_Reason_Code
{
unsafe {
__gcc_personality_v0(state, ue_header, context)
}
}
#[lang = "eh_personality_catch"]
#[no_mangle]
pub extern fn rust_eh_personality_catch(
state: uw::_Unwind_State,
_ue_header: *mut uw::_Unwind_Exception,
_context: *mut uw::_Unwind_Context
) -> uw::_Unwind_Reason_Code
{
if (state as c_int & uw::_US_ACTION_MASK as c_int)
== uw::_US_VIRTUAL_UNWIND_FRAME as c_int { // search phase
uw::_URC_HANDLER_FOUND // catch!
}
else { // cleanup phase
uw::_URC_INSTALL_CONTEXT
}
}
}
// Win64 SEH (see http://msdn.microsoft.com/en-us/library/1eyas8tf.aspx)
//
// This looks a bit convoluted because rather than implementing a native SEH
// handler, GCC reuses the same personality routine as for the other
// architectures by wrapping it with an "API translator" layer
// (_GCC_specific_handler).
#[cfg(all(windows, target_arch = "x86_64", not(test)))]
#[doc(hidden)]
#[allow(non_camel_case_types, non_snake_case)]
pub mod eabi {
pub use self::EXCEPTION_DISPOSITION::*;
use rt::libunwind as uw;
use libc::{c_void, c_int};
// Fake definitions; these are actually complicated structs,
// but we don't use the contents here.
pub type EXCEPTION_RECORD = c_void;
pub type CONTEXT = c_void;
pub type DISPATCHER_CONTEXT = c_void;
#[repr(C)]
#[derive(Copy, Clone)]
pub enum EXCEPTION_DISPOSITION {
ExceptionContinueExecution,
ExceptionContinueSearch,
ExceptionNestedException,
ExceptionCollidedUnwind
}
type _Unwind_Personality_Fn =
extern fn(
version: c_int,
actions: uw::_Unwind_Action,
exception_class: uw::_Unwind_Exception_Class,
ue_header: *mut uw::_Unwind_Exception,
context: *mut uw::_Unwind_Context
) -> uw::_Unwind_Reason_Code;
extern {
fn __gcc_personality_seh0(
exceptionRecord: *mut EXCEPTION_RECORD,
establisherFrame: *mut c_void,
contextRecord: *mut CONTEXT,
dispatcherContext: *mut DISPATCHER_CONTEXT
) -> EXCEPTION_DISPOSITION;
fn _GCC_specific_handler(
exceptionRecord: *mut EXCEPTION_RECORD,
establisherFrame: *mut c_void,
contextRecord: *mut CONTEXT,
dispatcherContext: *mut DISPATCHER_CONTEXT,
personality: _Unwind_Personality_Fn
) -> EXCEPTION_DISPOSITION;
}
#[lang = "eh_personality"]
#[no_mangle]
extern fn rust_eh_personality(
exceptionRecord: *mut EXCEPTION_RECORD,
establisherFrame: *mut c_void,
contextRecord: *mut CONTEXT,
dispatcherContext: *mut DISPATCHER_CONTEXT
) -> EXCEPTION_DISPOSITION
{
unsafe {
__gcc_personality_seh0(exceptionRecord, establisherFrame,
contextRecord, dispatcherContext)
}
}
#[lang = "eh_personality_catch"]
#[no_mangle]
pub extern fn rust_eh_personality_catch(
exceptionRecord: *mut EXCEPTION_RECORD,
establisherFrame: *mut c_void,
contextRecord: *mut CONTEXT,
dispatcherContext: *mut DISPATCHER_CONTEXT
) -> EXCEPTION_DISPOSITION
{
extern fn inner(
_version: c_int,
actions: uw::_Unwind_Action,
_exception_class: uw::_Unwind_Exception_Class,
_ue_header: *mut uw::_Unwind_Exception,
_context: *mut uw::_Unwind_Context
) -> uw::_Unwind_Reason_Code
{
if (actions as c_int & uw::_UA_SEARCH_PHASE as c_int) != 0 { // search phase
uw::_URC_HANDLER_FOUND // catch!
}
else { // cleanup phase
uw::_URC_INSTALL_CONTEXT
}
}
unsafe {
_GCC_specific_handler(exceptionRecord, establisherFrame,
contextRecord, dispatcherContext,
inner)
}
}
}