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Auto merge of #32900 - alexcrichton:panic2abort, r=nikomatsakis

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rustc: Implement custom panic runtimes

This commit is an implementation of [RFC 1513] which allows applications to
alter the behavior of panics at compile time. A new compiler flag, `-C panic`,
is added and accepts the values `unwind` or `panic`, with the default being
`unwind`. This model affects how code is generated for the local crate, skipping
generation of landing pads with `-C panic=abort`.

[RFC 1513]: https://github.com/rust-lang/rfcs/blob/master/text/1513-less-unwinding.md

Panic implementations are then provided by crates tagged with
`#![panic_runtime]` and lazily required by crates with
`#![needs_panic_runtime]`. The panic strategy (`-C panic` value) of the panic
runtime must match the final product, and if the panic strategy is not `abort`
then the entire DAG must have the same panic strategy.

With the `-C panic=abort` strategy, users can expect a stable method to disable
generation of landing pads, improving optimization in niche scenarios,
decreasing compile time, and decreasing output binary size. With the `-C
panic=unwind` strategy users can expect the existing ability to isolate failure
in Rust code from the outside world.

Organizationally, this commit dismantles the `sys_common::unwind` module in
favor of some bits moving part of it to `libpanic_unwind` and the rest into the
`panicking` module in libstd. The custom panic runtime support is pretty similar
to the custom allocator support with the only major difference being how the
panic runtime is injected (takes the `-C panic` flag into account).

Closes #32837
This commit is contained in:
bors 2016-05-09 18:23:48 -07:00
commit 72ed7e7894
81 changed files with 2323 additions and 932 deletions
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124
src/libstd/sys/unix/backtrace/tracing/gcc_s.rs
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@ -15,6 +15,7 @@ use mem;
use sync::StaticMutex;
use super::super::printing::print;
use unwind as uw;
#[inline(never)] // if we know this is a function call, we can skip it when
// tracing
@ -102,126 +103,3 @@ pub fn write(w: &mut Write) -> io::Result<()> {
uw::_URC_NO_REASON
}
}
/// Unwind library interface used for backtraces
///
/// Note that dead code is allowed as here are just bindings
/// iOS doesn't use all of them it but adding more
/// platform-specific configs pollutes the code too much
#[allow(non_camel_case_types)]
#[allow(non_snake_case)]
mod uw {
pub use self::_Unwind_Reason_Code::*;
use libc;
#[repr(C)]
pub enum _Unwind_Reason_Code {
_URC_NO_REASON = 0,
_URC_FOREIGN_EXCEPTION_CAUGHT = 1,
_URC_FATAL_PHASE2_ERROR = 2,
_URC_FATAL_PHASE1_ERROR = 3,
_URC_NORMAL_STOP = 4,
_URC_END_OF_STACK = 5,
_URC_HANDLER_FOUND = 6,
_URC_INSTALL_CONTEXT = 7,
_URC_CONTINUE_UNWIND = 8,
_URC_FAILURE = 9, // used only by ARM EABI
}
pub enum _Unwind_Context {}
pub type _Unwind_Trace_Fn =
extern fn(ctx: *mut _Unwind_Context,
arg: *mut libc::c_void) -> _Unwind_Reason_Code;
extern {
// No native _Unwind_Backtrace on iOS
#[cfg(not(all(target_os = "ios", target_arch = "arm")))]
pub fn _Unwind_Backtrace(trace: _Unwind_Trace_Fn,
trace_argument: *mut libc::c_void)
-> _Unwind_Reason_Code;
// available since GCC 4.2.0, should be fine for our purpose
#[cfg(all(not(all(target_os = "android", target_arch = "arm")),
not(all(target_os = "linux", target_arch = "arm"))))]
pub fn _Unwind_GetIPInfo(ctx: *mut _Unwind_Context,
ip_before_insn: *mut libc::c_int)
-> libc::uintptr_t;
#[cfg(all(not(target_os = "android"),
not(all(target_os = "linux", target_arch = "arm"))))]
pub fn _Unwind_FindEnclosingFunction(pc: *mut libc::c_void)
-> *mut libc::c_void;
}
// On android, the function _Unwind_GetIP is a macro, and this is the
// expansion of the macro. This is all copy/pasted directly from the
// header file with the definition of _Unwind_GetIP.
#[cfg(any(all(target_os = "android", target_arch = "arm"),
all(target_os = "linux", target_arch = "arm")))]
pub unsafe fn _Unwind_GetIP(ctx: *mut _Unwind_Context) -> libc::uintptr_t {
#[repr(C)]
enum _Unwind_VRS_Result {
_UVRSR_OK = 0,
_UVRSR_NOT_IMPLEMENTED = 1,
_UVRSR_FAILED = 2,
}
#[repr(C)]
enum _Unwind_VRS_RegClass {
_UVRSC_CORE = 0,
_UVRSC_VFP = 1,
_UVRSC_FPA = 2,
_UVRSC_WMMXD = 3,
_UVRSC_WMMXC = 4,
}
#[repr(C)]
enum _Unwind_VRS_DataRepresentation {
_UVRSD_UINT32 = 0,
_UVRSD_VFPX = 1,
_UVRSD_FPAX = 2,
_UVRSD_UINT64 = 3,
_UVRSD_FLOAT = 4,
_UVRSD_DOUBLE = 5,
}
type _Unwind_Word = libc::c_uint;
extern {
fn _Unwind_VRS_Get(ctx: *mut _Unwind_Context,
klass: _Unwind_VRS_RegClass,
word: _Unwind_Word,
repr: _Unwind_VRS_DataRepresentation,
data: *mut libc::c_void)
-> _Unwind_VRS_Result;
}
let mut val: _Unwind_Word = 0;
let ptr = &mut val as *mut _Unwind_Word;
let _ = _Unwind_VRS_Get(ctx, _Unwind_VRS_RegClass::_UVRSC_CORE, 15,
_Unwind_VRS_DataRepresentation::_UVRSD_UINT32,
ptr as *mut libc::c_void);
(val & !1) as libc::uintptr_t
}
// This function doesn't exist on Android or ARM/Linux, so make it same
// to _Unwind_GetIP
#[cfg(any(all(target_os = "android", target_arch = "arm"),
all(target_os = "linux", target_arch = "arm")))]
pub unsafe fn _Unwind_GetIPInfo(ctx: *mut _Unwind_Context,
ip_before_insn: *mut libc::c_int)
-> libc::uintptr_t
{
*ip_before_insn = 0;
_Unwind_GetIP(ctx)
}
// This function also doesn't exist on Android or ARM/Linux, so make it
// a no-op
#[cfg(any(target_os = "android",
all(target_os = "linux", target_arch = "arm")))]
pub unsafe fn _Unwind_FindEnclosingFunction(pc: *mut libc::c_void)
-> *mut libc::c_void
{
pc
}
}